Acalculous Cholecystitis in Critical Care

Quick Answer Card

Definition: Acute inflammatory disease of the gallbladder occurring without gallstones, predominantly affecting critically ill patients with multifactorial pathophysiology including bile stasis, ischemia, and systemic inflammation.

Key Points (30-second summary):

• Incidence: 5-10% of all acute cholecystitis; 0.5-1.5% of ICU admissions; 90% occur in critically ill patients (PMID: 12764181)
• Risk Factors: Sepsis, major surgery (esp. cardiac), trauma, burns, TPN, mechanical ventilation, vasopressors
• Diagnosis: Ultrasound first-line (gallbladder wall >3.5mm, pericholecystic fluid, distension >5cm); CT for complications; HIDA unreliable in ICU
• Tokyo Guidelines 2018: Grade I-III severity based on organ dysfunction; most ICU patients are Grade III
• Treatment: Resuscitation + broad-spectrum antibiotics + source control (cholecystostomy if unstable, cholecystectomy if fit for surgery)
• Mortality: 30-50% in ICU (vs 1-4% calculous); increases with delayed diagnosis and gangrenous changes
• Key Complication: Gangrenous cholecystitis occurs in 50% of AAC (vs 2-5% calculous) (PMID: 25414341)

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CICM Exam Focus

Second Part Written (SAQ)

Common Stems:

• "A 67-year-old man is day 7 post-CABG with unexplained fever and rising lactate. Outline your diagnostic approach to suspected acalculous cholecystitis."
• "Discuss the role of percutaneous cholecystostomy versus surgical cholecystectomy in the management of acute cholecystitis in the ICU."
• "Describe the pathophysiology of acalculous cholecystitis in critically ill patients."

Expected Knowledge:

• Tokyo Guidelines 2018 severity grading and its application to ICU patients
• Diagnostic imaging modalities: USS vs CT vs HIDA (sensitivity/specificity, limitations in ICU)
• Pathophysiology: bile stasis, ischemia, cytokine-mediated injury
• Source control options and decision-making in unstable patients
• Antibiotic selection and duration (SIS guidelines, STOP-IT trial)

Second Part Hot Case

Typical Presentations:

1. Post-cardiac surgery patient with unexplained sepsis and RUQ tenderness
2. Burns patient on TPN with rising inflammatory markers and hyperbilirubinemia
3. Trauma patient with MOF and suspected intra-abdominal sepsis

Examiner Expectations:

• Systematic approach to unexplained sepsis in ICU
• Recognition of high-risk patient groups
• Interpretation of bedside ultrasound findings
• Articulation of source control strategy based on patient stability
• Discussion of surgical versus interventional radiology involvement
• Communication with family regarding prognosis and management options

Second Part Viva

Key Topics:

1. Pathophysiology and risk factors for AAC in ICU
2. Diagnostic criteria and imaging modalities
3. Tokyo Guidelines 2018 severity grading
4. Source control: cholecystostomy vs cholecystectomy (CHOCOLATE trial)
5. Antimicrobial therapy and duration (STOP-IT trial)
6. Complications: gangrenous, emphysematous, perforation
7. Special populations: post-cardiac surgery, burns, immunocompromised
8. Prognosis and mortality predictors

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Key Points

1. Acalculous cholecystitis accounts for 5-10% of all acute cholecystitis but carries 30-50% mortality in ICU due to delayed diagnosis, underlying critical illness, and rapid progression to gangrene (PMID: 12764181, PMID: 34200371).

2. Bile stasis, ischemia, and systemic inflammation form the pathophysiological triad; critically ill patients develop all three simultaneously (lack of CCK stimulation, splanchnic hypoperfusion, cytokine-mediated endothelial injury) (PMID: 25232125).

3. Gangrenous cholecystitis occurs in 50% of AAC (vs 2-5% of calculous cholecystitis), reflecting the ischemic pathogenesis and necessity for early intervention (PMID: 25414341).

4. Diagnosis is challenging in sedated ICU patients; Murphy's sign is unreliable; 30-50% present with unexplained sepsis as the primary manifestation (PMID: 11210497).

5. Ultrasound is first-line (sensitivity 50-70%, specificity 80-90%); key findings: wall thickening >3.5mm, pericholecystic fluid, gallbladder distension >5cm, absence of stones (PMID: 30190543).

6. CT is preferred for detecting complications (gangrenous changes, perforation, emphysematous cholecystitis) with sensitivity >90% for complicated disease (PMID: 17215336).

7. HIDA scan has high false-positive rate (30-50%) in ICU patients on TPN, prolonged fasting, or with hepatic dysfunction; not recommended as first-line in critically ill (PMID: 2194371).

8. Tokyo Guidelines 2018 (TG18) classify severity: Grade I (mild), Grade II (moderate - local inflammation/WBC >18k), Grade III (severe - organ dysfunction); most ICU patients with AAC are Grade III (PMID: 29073648).

9. Percutaneous cholecystostomy (PC) is appropriate for truly unstable patients unfit for anaesthesia; CHOCOLATE trial showed laparoscopic cholecystectomy superior in high-risk but operable patients (PMID: 30262261).

10. Antibiotic therapy: Broad-spectrum coverage for enteric gram-negatives and anaerobes; duration 4 days after source control (STOP-IT trial); discontinue within 24 hours if successful cholecystectomy without extension (PMID: 28085573, PMID: 25992746).

11. Australian context: eTG recommends piperacillin-tazobactam or meropenem for healthcare-associated biliary sepsis; consider local antibiogram and prior colonisation.

12. High-risk populations: Post-cardiac surgery (1-4% incidence), burns >30% TBSA, major trauma, prolonged TPN (>2 weeks), immunocompromised patients (PMID: 15337517, PMID: 3514757).

13. Mortality predictors: Delayed diagnosis >48 hours, gangrenous changes, perforation, organ failure at presentation, immunosuppression, advanced age (PMID: 25232125).

14. Indigenous health considerations: Aboriginal, Torres Strait Islander, and Māori patients may present later due to geographic isolation; involve Aboriginal Health Workers and cultural liaison early; consider health literacy barriers.

15. Prevention strategies: Enteral nutrition where possible (stimulates CCK), adequate resuscitation to maintain splanchnic perfusion, minimise opioid use (Sphincter of Oddi spasm), prophylactic cholecystectomy controversial in high-risk patients (PMID: 11113470).

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1. Definition and Epidemiology

1.1 Definition

Acute acalculous cholecystitis (AAC) is defined as acute inflammation of the gallbladder in the absence of gallstones, characterised by:

• Histopathology: Mucosal necrosis, oedema, haemorrhage, and variable transmural inflammation
• Clinical presentation: Features of acute cholecystitis without demonstrable calculi on imaging
• Temporal association: Typically occurring in the context of critical illness, major surgery, or significant physiological stress (PMID: 12764181)

1.2 Epidemiology

Incidence

Demographics

• Age: Mean age 50-65 years; higher incidence with advancing age
• Sex: Male predominance (60-70%), contrasting with calculous cholecystitis which is female-predominant
• Comorbidities: Diabetes (15-30%), cardiovascular disease (40-50%), immunosuppression (10-20%)

Australian/New Zealand Data

• ANZICS-APD Registry: Limited specific data on AAC; included within broader "intra-abdominal sepsis" category
• Remote/rural considerations: Delayed presentation and transfer to surgical centres may increase morbidity
• Indigenous populations: Higher prevalence of risk factors (diabetes, renal disease) may increase susceptibility

1.3 Risk Factors

Major Risk Factors

Pathophysiological Triad

1. Bile Stasis: Absent enteral feeding → no CCK release → gallbladder atony → concentrated bile with increased toxicity
2. Ischemia: Shock, vasopressors, low cardiac output → splanchnic hypoperfusion → mucosal injury
3. Systemic Inflammation: SIRS/sepsis → endothelial activation → increased vascular permeability → gallbladder wall oedema

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2. Applied Basic Sciences

2.1 Anatomy

Gallbladder Structure

The gallbladder is a pear-shaped hollow organ located in the gallbladder fossa on the inferior surface of the liver (segments IVb and V).

Dimensions:

• Length: 7-10 cm
• Width: 3-4 cm
• Capacity: 30-50 mL (can concentrate bile up to 10-fold)

Anatomical Divisions:

• Fundus: Rounded blind end projecting beyond the inferior liver margin; most common site of perforation (limited blood supply)
• Body: Main portion; in contact with the hepatic flexure of colon and first part of duodenum
• Infundibulum (Hartmann's pouch): Dilated region where stones commonly impact
• Neck: Narrows to join the cystic duct; contains the spiral valve of Heister

Biliary Anatomy

Hepatocystic Triangle (Calot's Triangle):

• Boundaries: Cystic duct (inferolateral), common hepatic duct (medial), inferior surface of liver (superior)
• Contents: Cystic artery, cystic lymph node (Lund's node), variable anatomy of aberrant ducts
• Clinical significance: Critical safety zone during cholecystectomy; aberrant anatomy in 25-50% of patients

Bile Duct Anatomy:

• Right and left hepatic ducts → Common hepatic duct (CHD)
• CHD + Cystic duct → Common bile duct (CBD) (length 6-8 cm, diameter <6mm)
• CBD enters the second part of duodenum at the major duodenal papilla (ampulla of Vater)

Vascular Supply

Arterial:

• Cystic artery: Usually single branch from right hepatic artery (70%)
• Variant anatomy: Double cystic artery (25%), origin from other vessels (gastroduodenal, left hepatic, superior mesenteric)
• "Caterpillar hump": Tortuous right hepatic artery crossing in front of cystic duct (15%)

Venous:

• Small veins drain directly into liver through gallbladder fossa (cholecystohepatic veins)
• Cystic veins drain to portal vein or hepatic parenchyma

Lymphatic Drainage:

• Cystic lymph node (node of Lund) → hepatic nodes → coeliac nodes
• May also drain to posterior pancreaticoduodenal nodes

Innervation

• Sympathetic: Coeliac plexus (T7-T9) - inhibits contraction, causes vasoconstriction
• Parasympathetic: Vagus nerve - stimulates contraction (via CCK pathway)
• Sensory: Referred pain to right shoulder (phrenic nerve C3-5) and epigastrium

CICM First Part Link

Understanding gallbladder vascular supply explains the ischemic pathogenesis of AAC. The cystic artery is an end-artery without significant collateral supply, making the gallbladder vulnerable to ischaemic injury during low-flow states or splanchnic vasoconstriction.

2.2 Physiology (Biliary)

Bile Formation and Composition

Bile is produced continuously by hepatocytes (500-1000 mL/day) and concentrated in the gallbladder.

Bile Composition (PMID: 30214649):

Bile Acid Synthesis and Enterohepatic Circulation

Primary Bile Acids (synthesised from cholesterol in liver):

• Cholic acid (CA)
• Chenodeoxycholic acid (CDCA)

Conjugation:

• Conjugated with glycine (75%) or taurine (25%) to form bile salts
• Increases water solubility at intestinal pH
• Enables micelle formation

Enterohepatic Circulation (PMID: 15153272):

1. Bile salts secreted into duodenum with meal
2. Participate in fat digestion and absorption
3. 95% reabsorbed in terminal ileum via ASBT (Apical Sodium-dependent Bile acid Transporter)
4. Return to liver via portal circulation
5. Cycle repeated 6-10 times daily

Secondary Bile Acids (formed by bacterial deconjugation in colon):

• Deoxycholic acid (from cholic acid)
• Lithocholic acid (from CDCA) - hepatotoxic

Cholecystokinin (CCK) and Gallbladder Motility

CCK Physiology (PMID: 12524401, PMID: 17210874):

• Source: I-cells in duodenal and jejunal mucosa
• Stimuli: Long-chain fatty acids, amino acids (tryptophan, phenylalanine), gastric acid
• Receptors: CCK-1 receptors on gallbladder smooth muscle
• Actions:
  • Gallbladder contraction (ejection fraction 50-70%)
  • Sphincter of Oddi relaxation (via NO pathway)
  • Pancreatic enzyme secretion
  • Gastric emptying inhibition

Interdigestive Motility:

• Periodic gallbladder contractions during fasting (part of migrating motor complex)
• Phase III of MMC includes partial gallbladder emptying
• Absent in prolonged ICU admission with opioids/sedation

Relevance to AAC Pathophysiology

In critically ill patients:

1. No enteral nutrition → No CCK release → Gallbladder atony
2. Opioids → Sphincter of Oddi spasm → Bile stasis
3. Sedation → Reduced vagal tone → Impaired contraction
4. Concentrated bile → Increased toxicity → Mucosal injury

CICM First Part Link

Understanding CCK physiology explains why enteral feeding is protective against AAC. Even trophic feeding (10-20 mL/hr) can stimulate CCK release and maintain gallbladder motility.

2.3 Pathology (Inflammation Cascade, Ischemia)

Pathophysiology of Acalculous Cholecystitis

AAC results from the convergence of three pathophysiological mechanisms (PMID: 25232125):

1. Bile Stasis

• Absent CCK stimulation → Gallbladder hypomotility
• Bile concentration increases 10-20 fold
• Lysophosphatidylcholine (derived from bile phospholipids) becomes cytotoxic
• Mucosal injury and inflammation ensue

2. Ischemia-Reperfusion Injury

• Splanchnic hypoperfusion (shock, vasopressors, cardiac surgery)
• Cystic artery is an end-artery with limited collaterals
• Ischemic injury to gallbladder mucosa (most vulnerable layer)
• Reperfusion generates reactive oxygen species
• Endothelial dysfunction and increased permeability

3. Systemic Inflammatory Response

• SIRS/Sepsis → Elevated TNF-α, IL-1β, IL-6
• Endothelial activation and glycocalyx injury
• Microvascular thrombosis (DIC component)
• Factor XII activation (Hageman factor) → Coagulation cascade
• Complement activation → Membrane attack complex

Inflammatory Cascade in AAC

Ischemia + Bile Stasis + SIRS
         ↓
   Mucosal Injury
         ↓
   Prostaglandin Release (PGE₂, PGF₂α)
         ↓
   Increased Intraluminal Pressure
         ↓
   Impaired Venous/Lymphatic Drainage
         ↓
   Wall Edema and Hemorrhage
         ↓
   Secondary Bacterial Infection
         ↓
   Transmural Necrosis (Gangrene)
         ↓
   Perforation

Histopathological Stages

Why AAC Progresses Faster Than Calculous Cholecystitis

Key PMID: 25414341 (Risk factors and outcomes of gangrenous cholecystitis)

Microbiology

Common Pathogens (PMID: 11210497):

Polymicrobial Infection: 30-50% of cases

Important Points:

• Culture-positive in only 50-70% of cases (often "chemical" cholecystitis initially)
• Blood cultures positive in 20-40%
• Bile cultures more sensitive if obtained during cholecystostomy/surgery

CICM First Part Link

Understanding the ischemia-reperfusion injury mechanism links to broader ICU pathophysiology concepts including sepsis, shock, and reactive oxygen species generation.

2.4 Pharmacology (Antibiotics, Vasopressors)

Antibiotic Therapy for Biliary Sepsis

Principles:

1. Cover enteric gram-negatives (Enterobacteriaceae)
2. Cover anaerobes (Bacteroides)
3. Consider Enterococcus in healthcare-associated/post-procedural
4. De-escalate based on cultures and source control
5. Limit duration after source control (STOP-IT trial)

Empiric Antibiotic Selection

Australian eTG Recommendations (Therapeutic Guidelines: Antibiotic):

Key Points:

• Extended infusion beta-lactams: Piperacillin-tazobactam 4.5g over 4 hours; meropenem 1g over 3 hours (optimises time above MIC)
• Aminoglycosides: Use with caution in AKI; monitor levels
• Antifungal coverage: Consider fluconazole if prolonged ICU, prior antibiotics, TPN, abdominal surgery
• Duration: 4 days after adequate source control (SIS Guidelines, PMID: 28085573)

STOP-IT Trial Summary (PMID: 25992746)

Design: Multicentre RCT, 518 patients with complicated intra-abdominal infection with source control

Comparison: Fixed 4-day antibiotic course vs. standard therapy (mean 8 days)

Results:

• Composite outcome (SSI, recurrent abscess, death) similar: 21.8% vs 22.3%
• No difference in mortality or infectious complications
• 4-day group had less C. difficile infection

Conclusion: 4 days of antibiotics after adequate source control is non-inferior to longer courses

Clinical Implication: Stop antibiotics at 4 days post-source control, regardless of persistent fever/leukocytosis

Vasopressor Effects on Splanchnic Circulation

Understanding vasopressor pharmacology is essential as these agents may contribute to AAC pathogenesis:

Clinical Practice:

• Use lowest effective vasopressor dose
• Target MAP 65 mmHg (higher targets not beneficial for splanchnic perfusion)
• Early enteral nutrition may be more protective than vasopressor choice
• Consider AAC in patients on prolonged high-dose vasopressors

Analgesia Considerations

Practice Point: Fentanyl or remifentanil preferred in patients at high risk of AAC

CICM First Part Link

Extended infusion beta-lactam dosing links to time-dependent antibiotic pharmacodynamics. Understanding vasopressor receptor pharmacology (α₁, β₁, V₁) is First Part knowledge applied to clinical decision-making.

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3. Clinical Presentation

3.1 Classic Presentation

The classic triad of acute cholecystitis (RUQ pain, fever, Murphy's sign) is unreliable in critically ill patients.

Traditional Features (when assessable):

• Right upper quadrant pain/tenderness
• Fever (>38°C)
• Nausea and vomiting
• Positive Murphy's sign (inspiratory arrest with RUQ palpation)

3.2 ICU-Specific Presentations

In sedated, mechanically ventilated ICU patients, AAC typically presents as (PMID: 11210497):

3.3 Atypical Presentations in Special Populations

Post-Cardiac Surgery (PMID: 15337517)

• Often presents day 5-10 post-operatively
• May be masked by expected post-operative inflammation
• Low cardiac output syndrome may be sole manifestation
• Higher index of suspicion required

Burns Patients (PMID: 3514757)

• Hypermetabolic state obscures diagnosis
• Baseline leukocytosis and fever from burn wound
• May present as sudden haemodynamic deterioration
• Often discovered during investigation of persistent sepsis

Immunocompromised

• Blunted inflammatory response
• May lack fever, leukocytosis
• CMV cholecystitis in AIDS patients
• Cryptosporidium, microsporidium in advanced HIV
• Consider acalculous cholangiopathy

Elderly

• Vague symptoms (malaise, confusion)
• Absence of localising signs
• Higher rate of complications at diagnosis
• Often Grade III at presentation

3.4 Diagnostic Challenges in Sedated Patients

Why Diagnosis is Delayed:

1. Unable to report pain
2. Murphy's sign unreliable under sedation
3. Physical examination limited (positioning, dressings, wounds)
4. Multiple potential sources of sepsis (lines, lungs, abdomen)
5. Baseline inflammation from critical illness

High-Risk Patients Requiring Active Surveillance:

• Cardiac surgery patients not progressing expected course
• Burns >30% TBSA
• Polytrauma with ISS >25
• Prolonged TPN (>7-10 days)
• Patients on high-dose vasopressors >48 hours
• Unexplained sepsis after exclusion of common sources

3.5 Severity Assessment: Tokyo Guidelines 2018 (TG18)

Tokyo Guidelines 2018 Severity Grading (PMID: 29073648):

Grade I: Mild

• Acute cholecystitis not meeting Grade II or III criteria
• No organ dysfunction
• Limited local inflammation
• Healthy patient with mild disease

Grade II: Moderate

Presence of ONE or more of:

• Elevated WBC >18,000/mm³
• Palpable tender mass in RUQ
• Duration of symptoms >72 hours
• Marked local inflammation:
  • Gangrenous cholecystitis
  • Pericholecystic abscess
  • Biliary peritonitis
  • Emphysematous cholecystitis

Grade III: Severe

Associated with organ dysfunction in ANY system:

• Cardiovascular: Hypotension requiring dopamine ≥5 μg/kg/min or any noradrenaline
• Neurological: Decreased level of consciousness
• Respiratory: PaO₂/FiO₂ ratio <300
• Renal: Oliguria or creatinine >177 μmol/L (>2.0 mg/dL)
• Hepatic: INR >1.5
• Haematological: Platelets <100,000/mm³

ICU Implication: Most ICU patients with AAC will be Grade III by definition (organ support is common)

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4. Investigations

4.1 Laboratory Investigations

Routine Blood Tests

Microbiological Investigations

Organisms to Target:

• Gram-negatives: E. coli, Klebsiella, Enterobacter, Pseudomonas
• Gram-positives: Enterococcus spp.
• Anaerobes: Bacteroides fragilis, Clostridium spp.

4.2 Imaging Modalities

Ultrasound (First-Line)

Technique: Bedside or radiology; curvilinear probe 3.5-5 MHz; patient supine or left lateral decubitus

Diagnostic Criteria for AAC:

*Sensitivity reduced in sedated patients

Limitations in ICU:

• Patient positioning difficulties
• Bowel gas obscuring view
• Sedation eliminates Murphy's sign utility
• Sludge common in prolonged fasting (not specific)
• Wall thickening may be due to hypoalbuminemia, ascites, hepatitis

Sensitivity/Specificity Overall: 50-70% / 80-90% (PMID: 30190543)

CT Abdomen with Contrast (Best for Complications)

Indications:

• Equivocal ultrasound findings
• Suspected complications (gangrene, perforation, emphysematous)
• Alternative diagnoses being considered
• Pre-procedural planning

Diagnostic Criteria:

Sensitivity/Specificity for Complicated AAC: >90% / >95%

HIDA Scan (Cholescintigraphy)

Principle: Tc-99m-HIDA injected IV, taken up by hepatocytes, excreted into bile. Normal gallbladder fills within 1 hour. Non-visualisation at 4 hours (or after morphine augmentation) indicates cystic duct obstruction.

Limitations in ICU (PMID: 2194371):

Recommendation: HIDA scan is NOT recommended as first-line in critically ill patients due to high false-positive rate and impracticality

Comparison of Imaging Modalities

*General population **ICU population

4.3 Diagnostic Criteria: Tokyo Guidelines 2018 (TG18)

TG18 Diagnostic Criteria for Acute Cholecystitis (PMID: 29073648):

A. Local Signs of Inflammation

1. Murphy's sign
2. RUQ mass/pain/tenderness

B. Systemic Signs of Inflammation

1. Fever (>38°C)
2. Elevated CRP (>30 mg/L)
3. Elevated WBC (>10,000/mm³)

C. Imaging Findings

• Characteristic imaging findings of acute cholecystitis (wall thickening, pericholecystic fluid, gallbladder distension)

Definite Diagnosis: A + B + C Suspected Diagnosis: A + B

ICU Modification:

• Murphy's sign unreliable in sedated patients
• Imaging takes increased importance
• Consider AAC with unexplained sepsis + imaging findings in high-risk patient

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5. ICU Management

5.1 Resuscitation

Initial Resuscitation (Surviving Sepsis Principles):

Vasopressor Selection:

• Noradrenaline first-line
• Vasopressin as adjunct (may worsen splanchnic ischaemia at high doses)
• Avoid dopamine (higher arrhythmia risk)

Organ Support:

• Mechanical ventilation as required
• Renal replacement therapy if indicated
• Blood products for coagulopathy/anaemia as indicated

5.2 Antimicrobial Therapy

Australian eTG Recommendations

Community-Acquired Moderate Biliary Sepsis:

Amoxicillin-clavulanate 1.2 g IV 8-hourly
+ Gentamicin 4-7 mg/kg IV daily (single dose)

OR

Ceftriaxone 2 g IV daily
+ Metronidazole 500 mg IV 12-hourly

Severe/Healthcare-Associated Biliary Sepsis:

Piperacillin-tazobactam 4.5 g IV 6-hourly (extended infusion over 4 hours)

OR

Meropenem 1 g IV 8-hourly (extended infusion over 3 hours)
[If ESBL colonised or previous ESBL infection]

If Enterococcus Suspected (post-procedural, healthcare-associated):

Add: Ampicillin 2 g IV 6-hourly
OR: Vancomycin 25-30 mg/kg load, then 15-20 mg/kg 8-12 hourly (target AUC 400-600)

If Candida Suspected (prolonged ICU, prior antibiotics, TPN):

Add: Fluconazole 800 mg load, then 400 mg daily
OR: Anidulafungin 200 mg load, then 100 mg daily (if prior azole exposure)

Duration of Therapy

Based on STOP-IT Trial and SIS Guidelines (PMID: 25992746, PMID: 28085573):

Clinical Application:

• "Adequate source control" = Infected focus removed or drained
• Do NOT extend antibiotics for persistent fever/leukocytosis if source controlled
• Investigate for other sources if not improving

5.3 Source Control

Timing: Within 12 hours of diagnosis if possible; delay increases mortality (PMID: 12764181)

Decision-Making Algorithm

                    Suspected AAC
                         │
                         ▼
               ┌─────────────────────┐
               │   Resuscitation +    │
               │     Antibiotics      │
               └─────────────────────┘
                         │
                         ▼
               ┌─────────────────────┐
               │    Fit for surgery?  │
               └─────────────────────┘
                    │           │
                   YES          NO
                    │           │
                    ▼           ▼
         ┌────────────────┐ ┌────────────────┐
         │ Laparoscopic   │ │ Percutaneous   │
         │ Cholecystectomy│ │ Cholecystostomy│
         └────────────────┘ └────────────────┘
                    │           │
                    ▼           ▼
              Definitive    Clinical
              Treatment     Improvement?
                               │
                          YES / NO
                           │     │
                           ▼     ▼
                    Interval  Investigate
                    Cholecystectomy Alternative
                    (6-8 weeks)    Source

Laparoscopic Cholecystectomy

Indications:

• Patient fit for general anaesthesia
• Grade I-II cholecystitis
• Grade III if operable after resuscitation
• Evidence of complications (gangrene, perforation) - may require open approach

CHOCOLATE Trial Evidence (PMID: 30262261):

• 142 high-risk patients (APACHE II 7-14) with acute cholecystitis
• Randomised to laparoscopic cholecystectomy vs. percutaneous cholecystostomy
• Major complications: 12% surgery vs. 44% drainage (RR 0.27)
• Recurrence: 5% surgery vs. 53% drainage
• Trial stopped early due to clear superiority of surgery
• Conclusion: Laparoscopic cholecystectomy superior if patient can tolerate surgery

Implication for ICU: Percutaneous cholecystostomy should be reserved for patients truly unfit for ANY surgery, not simply as a "safer" option

Percutaneous Cholecystostomy (PC)

Indications (PMID: 30190543):

• Truly unfit for general anaesthesia (severe cardiac, respiratory failure)
• Extremely high surgical risk (ongoing resuscitation, coagulopathy)
• Bridge to interval cholecystectomy in high-risk patients
• Failed conservative management

Technique:

1. Transhepatic (preferred) or transperitoneal approach
2. Ultrasound or CT guidance
3. Seldinger technique with 8-12 Fr locking pigtail catheter
4. Confirm position with contrast cholecystogram
5. Connect to external drainage

Success Rate: Clinical improvement in 80-90% within 24-48 hours

Complications:

• Catheter dislodgement (5-10%)
• Bile leak (5-10%)
• Bleeding (2-5%)
• Recurrent cholecystitis (30-50% if not followed by cholecystectomy)

Duration: Leave in situ for minimum 3-4 weeks to allow tract maturation before removal; consider interval cholecystectomy

Open Cholecystectomy

Indications:

• Gangrenous cholecystitis with perforation
• Generalised peritonitis
• Failed laparoscopic approach (conversion rate 10-30% in acute setting)
• Anatomical difficulty (Mirizzi syndrome, hostile abdomen)

Considerations:

• Higher morbidity in critically ill patients
• May require temporary abdominal closure (damage control surgery)
• Cholecystostomy tube may be placed if unsafe to complete cholecystectomy

5.4 Supportive Care

Nutrition

• Enteral nutrition preferred - Stimulates CCK, prevents bile stasis
• Trophic feeding (10-20 mL/hr) may be protective
• If TPN required, minimise duration; consider CCK analogue (investigational)

Venous Thromboembolism Prophylaxis

• Standard mechanical and pharmacological prophylaxis
• May need to hold anticoagulation peri-procedurally

Glycaemic Control

• Target glucose 6-10 mmol/L
• Higher glucose targets may be appropriate in septic shock initially

Analgesia

• Consider fentanyl/remifentanil over morphine (less Sphincter of Oddi spasm)
• Multimodal analgesia to minimise opioid requirements

Monitoring

• Serial lactate (every 4-6 hours until stable)
• Daily LFTs until normalising
• Serial imaging if not improving

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6. Monitoring and Complications

6.1 Monitoring Parameters

6.2 Expected Clinical Course

With Successful Source Control:

• Clinical improvement within 24-48 hours
• Defervescence within 48-72 hours
• Lactate normalisation within 24 hours
• LFTs improving by day 3-5
• WBC/CRP down-trending by day 2-3

Red Flags for Failure/Complication:

• Persistent/worsening hypotension
• Rising lactate despite resuscitation
• Failure to defervesce by 72 hours
• Worsening LFTs
• Bile leak (if PC in situ)
• New organ dysfunction

6.3 Complications

Gangrenous Cholecystitis (PMID: 25414341, PMID: 30336625)

Incidence: 40-50% of AAC (vs 2-5% of calculous cholecystitis)

Risk Factors:

• Age >51 years
• Male sex
• Diabetes mellitus
• WBC >17,000/mm³
• Elevated CRP
• Delayed presentation (>72 hours)
• Cardiovascular disease

Clinical Features:

• Paradoxical improvement in pain (necrosis of sensory nerves)
• High fever, tachycardia
• Marked leukocytosis
• Rapid deterioration

Imaging Signs:

• Irregular/absent gallbladder wall enhancement on CT
• Intramural haemorrhage
• Membranous structures in lumen
• Pericholecystic abscess

Management: Urgent cholecystectomy (open approach may be required)

Mortality: 15-25%

Emphysematous Cholecystitis (PMID: 17215336, PMID: 32644265)

Incidence: 1-3% of acute cholecystitis; more common in AAC

Risk Factors:

• Diabetes mellitus (30-50% of cases)
• Male sex (3:1)
• Vascular disease
• Immunosuppression

Pathogens: Gas-forming organisms

• Clostridium welchii (perfringens)
• E. coli
• Klebsiella spp.
• Streptococcus spp.

Imaging: Gas in gallbladder wall or lumen on plain X-ray, CT, or ultrasound

Management:

• Urgent cholecystectomy (SURGICAL EMERGENCY)
• Broad-spectrum antibiotics including anaerobic coverage
• High mortality if delayed (15-25%)

Gallbladder Perforation (PMID: 22003310, PMID: 21674252)

Niemeier Classification:

Incidence: 10-15% of AAC

Clinical Features:

• Sudden deterioration
• Generalised peritonitis (Type I)
• Paradoxical improvement then deterioration
• Septic shock

Imaging:

• Defect in gallbladder wall
• Free fluid with high attenuation
• Extraluminal gas
• Abscess formation

Management:

• Emergency surgery (open cholecystectomy + washout)
• Damage control surgery may be required
• Mortality 20-50%

Biliary Peritonitis

Pathophysiology:

• Bile leak from perforation or procedure
• Chemical peritonitis progressing to bacterial infection
• Systemic inflammatory response

Management:

• Emergency laparotomy
• Source control (repair/cholecystectomy)
• Peritoneal lavage
• Broad-spectrum antibiotics

Other Complications

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7. Prognosis and Outcomes

7.1 Mortality Data

AAC Mortality in ICU:

Comparison with Calculous Cholecystitis:

7.2 Prognostic Factors

Poor Prognostic Indicators (PMID: 25232125, PMID: 34200371):

Favourable Prognostic Factors:

• Early diagnosis and source control (<24 hours)
• Edematous (non-gangrenous) changes
• Younger age
• Single organ dysfunction
• Successful percutaneous drainage with clinical response

7.3 ICU Length of Stay

Expected LOS:

• Uncomplicated AAC with successful source control: 5-10 days
• Gangrenous/complicated: 14-28 days
• Multiple organ failure: >30 days

Factors Prolonging LOS:

• Delayed source control
• Complications requiring re-intervention
• Multi-organ dysfunction
• Nosocomial infections

7.4 Long-Term Outcomes

After Percutaneous Cholecystostomy:

• 30-50% recurrence if not followed by cholecystectomy
• Interval cholecystectomy recommended at 6-8 weeks if fit
• Some patients remain too frail for surgery (15-20%)

After Cholecystectomy:

• Definitive treatment; low recurrence
• Post-cholecystectomy syndrome in 5-10%

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8. Special Populations

8.1 Immunocompromised Patients

Unique Considerations:

• Blunted inflammatory response (may lack fever, leukocytosis)
• Atypical pathogens (CMV, Cryptosporidium, Microsporidia)
• Higher rate of complications
• Poor wound healing post-surgery

HIV/AIDS-Specific Issues (PMID: 25232125):

• Acalculous cholangiopathy (AIDS cholangiopathy)
• CMV cholecystitis
• Cryptosporidium/Microsporidia cholangitis
• Kaposi sarcoma involving gallbladder

Management Modifications:

• Lower threshold for imaging in unexplained sepsis
• Consider atypical pathogens
• Involve infectious diseases early
• May require longer antibiotic courses
• Higher surgical risk

Transplant Recipients:

• Immunosuppression masks symptoms
• Consider calcineurin inhibitor effects
• Monitor for opportunistic infections
• Involve transplant team in management

8.2 Post-Cardiac Surgery (PMID: 15337517, PMID: 25883236)

Incidence: 0.1-0.5% overall; up to 4% in high-risk patients

Risk Factors Specific to Cardiac Surgery:

• Cardiopulmonary bypass duration >2 hours
• Low cardiac output syndrome
• High-dose vasopressors
• Multiple blood transfusions
• Post-operative sepsis/pneumonia
• Pre-existing cardiovascular disease

Pathophysiology:

1. Low-flow state during CPB → Splanchnic hypoperfusion
2. SIRS from CPB → Systemic inflammation
3. Post-operative ileus → Bile stasis
4. Opioid analgesia → Sphincter of Oddi spasm

Clinical Presentation:

• Typically day 5-10 post-operatively
• May present as failure to wean, unexplained hypotension
• Masked by expected post-operative inflammation
• Higher index of suspicion required

Management:

• Early imaging in patients not progressing as expected
• Percutaneous cholecystostomy often preferred (avoid re-sternotomy)
• Anticoagulation considerations (post-valve surgery)
• Involve cardiac surgery team

8.3 Burns Patients (PMID: 3514757, PMID: 6721532, PMID: 21323770)

Incidence: 1-3% in burns >30% TBSA

Risk Factors:

• TBSA >30-40%
• Sepsis (strongest trigger)
• Prolonged TPN (>2 weeks)
• Multiple surgical procedures
• Ileus

Unique Challenges:

• Hypermetabolic state obscures diagnosis
• Baseline leukocytosis and fever from burn wound
• Difficult physical examination (dressings, contractures)
• Competing priorities (burn wound care, grafting)

Management Considerations:

• Early enteral feeding when possible
• Lower threshold for abdominal imaging in unexplained sepsis
• May need to delay grafting procedures if AAC diagnosed
• Percutaneous cholecystostomy often preferred initially

8.4 Indigenous Health Considerations

Aboriginal and Torres Strait Islander Populations

Health Disparities Relevant to AAC:

• Higher prevalence of risk factors:
  • Diabetes mellitus (3-4× higher prevalence)
  • Cardiovascular disease (2× higher)
  • Chronic kidney disease (4-5× higher)
  • Higher rates of severe infections and sepsis
• Geographic barriers:
  • Remote location delays presentation and transfer
  • Limited access to surgical services
  • May require retrieval by RFDS
• Social determinants:
  • Lower health literacy
  • Distrust of healthcare system (historical trauma)
  • Communication barriers (language, cultural)

Cultural Safety Considerations:

• Involve Aboriginal Health Worker (AHW) or Aboriginal Liaison Officer (ALO) early
• Extended family involvement in decision-making (collective approach)
• Respect for Elders and kinship structures
• "Sorry Business" may delay presentation or affect decision-making
• Men's and Women's Business considerations (same-gender care providers when possible)
• Clear, jargon-free communication with visual aids
• Allow adequate time for family discussions before major decisions

Management Modifications:

• Lower threshold for retrieval to tertiary centre
• Involve AHW/ALO in family meetings
• Consider extended family in treatment discussions
• Allow time for family to travel (may be from remote communities)
• Discharge planning must account for geographic isolation
• Follow-up arrangements with local Aboriginal Community Controlled Health Organisation (ACCHO)

Retrieval Considerations:

• RFDS or state retrieval service for inter-hospital transfer
• Telemedicine consultation with surgical/ICU specialists
• May need to stabilise with percutaneous cholecystostomy before transfer if unstable

Māori Health Considerations (New Zealand)

Health Disparities:

• Diabetes 2-3× higher prevalence
• Cardiovascular disease 1.5-2× higher
• May present later due to access barriers

Cultural Safety:

• Whānau (extended family) involvement in decision-making
• Tikanga Māori (cultural protocols) should be respected
• Kaumātua (Elders) may be consulted for major decisions
• Māori Health Workers can facilitate communication
• Consider Karakia (prayer) before procedures if requested
• Respect for Tapu (sacred) and Noa (common) distinctions regarding body and treatment

Practical Considerations:

• Involve Māori Health Workers/Cultural Advisors
• Allow time for whānau hui (family meetings)
• Consider spiritual/cultural needs alongside medical care
• Ensure follow-up is accessible (consider telehealth)

8.5 Elderly and Frail Patients

Unique Considerations:

• Vague, non-specific presentations
• Cognitive impairment may mask symptoms
• Lower threshold for complications
• Frailty increases surgical risk
• Goals of care discussions important

Management Modifications:

• Lower threshold for imaging
• Percutaneous cholecystostomy may be definitive treatment in very frail
• Clear discussion of prognosis with family
• May not be candidates for aggressive intervention

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9. Progressive Clinical Assessments

Foundation Tier (Basic Knowledge)

Question 1: A 58-year-old man is day 5 post-CABG. He has been on TPN and mechanical ventilation. The nurse notes a temperature of 38.5°C and rising lactate. What is the most appropriate initial imaging investigation?

Answer: Bedside abdominal ultrasound. This is first-line for suspected AAC as it is portable, non-invasive, avoids radiation and contrast, and can assess gallbladder wall thickness, pericholecystic fluid, and distension. CT is second-line if ultrasound is equivocal or complications are suspected.

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Question 2: List three major risk factors for acalculous cholecystitis in ICU patients.

Answer:

1. Prolonged fasting/TPN (>72 hours) - causes bile stasis from absent CCK stimulation
2. Shock requiring vasopressors - causes splanchnic hypoperfusion and ischaemic injury
3. Major surgery (especially cardiac surgery with CPB) - causes SIRS, low-flow states, and immobilisation

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Intermediate Tier (Clinical Application)

Question 3: A 65-year-old woman with 40% TBSA burns is day 10 post-admission. Despite adequate resuscitation and source control of her burn wounds, she develops unexplained fever and hypotension. Abdominal ultrasound shows gallbladder wall thickening (5mm), pericholecystic fluid, and no stones. LFTs show bilirubin 65 μmol/L, ALP 280 U/L.

a) What is the most likely diagnosis? b) How would you grade her severity using Tokyo Guidelines 2018? c) What source control option would you recommend?

Answer: a) Acute acalculous cholecystitis (AAC). Classic presentation in high-risk patient (burns, prolonged fasting, immobilisation) with imaging findings of cholecystitis without stones.

b) Grade III (Severe): She has organ dysfunction (cardiovascular - hypotension requiring vasopressors). Any organ dysfunction = Grade III.

c) Source control recommendation:

• If truly unfit for general anaesthesia (ongoing shock, coagulopathy): Percutaneous cholecystostomy (PC)
• If can tolerate surgery after resuscitation: Laparoscopic cholecystectomy is preferred (CHOCOLATE trial)
• Given burns context and likely competing surgical priorities, PC may be reasonable as initial approach with interval cholecystectomy planned

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Question 4: A 72-year-old man underwent percutaneous cholecystostomy for AAC 48 hours ago. Despite drainage and antibiotics, he remains febrile and requires increasing vasopressor support. What are your differential diagnoses and next steps?

Answer:

Differential diagnoses:

1. Inadequate source control (gangrenous cholecystitis not fully drained)
2. Gallbladder perforation
3. Alternative source of sepsis (line infection, pneumonia, other intra-abdominal)
4. Catheter malposition/blockage
5. Resistant organism
6. Pericholecystic abscess requiring additional drainage

Next steps:

1. CT abdomen with contrast - assess for gangrenous changes, perforation, abscess, catheter position
2. Review microbiology - cultures, sensitivities, consider resistant organisms
3. Evaluate catheter - check output, consider cholecystogram
4. Line/blood cultures - repeat to assess ongoing bacteraemia
5. Consider surgical consultation for cholecystectomy if gangrenous/perforated
6. Review antibiotics - broaden if needed, consider antifungal

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Advanced Tier (Exam-Level Synthesis)

Question 5: A 55-year-old Aboriginal man from a remote community presents to a regional hospital with septic shock. He has a history of diabetes and CKD Stage 4. CT shows acalculous cholecystitis with possible gangrenous changes. He requires noradrenaline 0.3 mcg/kg/min and is anuric. The nearest tertiary centre with hepatobiliary surgery is 6 hours by road (RFDS unavailable due to weather).

a) Outline your initial management priorities b) Discuss the source control options in this context c) What specific considerations apply to this patient's care?

Answer:

a) Initial management priorities:

1. Resuscitation: Fluid resuscitation (30 mL/kg), vasopressor optimisation (consider vasopressin as adjunct), correct coagulopathy
2. Antibiotics: Broad-spectrum within 1 hour - Meropenem (dose-adjusted for CKD) given diabetes, renal impairment, septic shock
3. Renal replacement therapy: Consider early RRT for fluid management, metabolic control
4. Source control: Urgent discussion with surgical/IR services
5. Retrieval: Liaise with retrieval service for earliest possible transfer despite weather

b) Source control options:

• Ideal: Transfer to tertiary centre for cholecystectomy (gangrenous changes)
• If unstable for transfer: Percutaneous cholecystostomy at regional centre if IR capability exists
• If no IR capability: May need to stabilise maximally and accept risk of transfer while severely unwell
• Consider: Telemedicine consultation with hepatobiliary surgeon/ICU specialist
• PC may be bridge to allow stabilisation before transfer/surgery

c) Specific considerations:

1. Indigenous health:

   • Involve Aboriginal Health Worker/Liaison Officer early
   • Contact family (may need time to travel from remote community)
   • Cultural considerations for decision-making (collective, Elder involvement)
   • Clear, jargon-free communication
   • Consider impact on Sorry Business or other cultural obligations

2. Comorbidities:

   • Diabetes: Higher risk of emphysematous cholecystitis, poor wound healing
   • CKD Stage 4: Drug dosing adjustments, may progress to dialysis dependence

3. Remote context:

   • Limited local surgical capability
   • Retrieval coordination essential
   • May need prolonged ICU stay at regional centre before safe transfer
   • Follow-up planning must account for geographic isolation
   • Involve ACCHO for discharge and follow-up

4. Prognosis discussion:

   • High mortality (50%+) with gangrenous AAC, shock, organ failure
   • Family should be involved in goals of care discussion
   • Allow time for family to arrive before major decisions if possible

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10. SAQ Practice

SAQ 1: Diagnosis and Initial Management of AAC (20 marks)

Stem: A 62-year-old man is day 8 post-emergency repair of a ruptured abdominal aortic aneurysm. He has been ventilated and on TPN since surgery. He developed fever (39.2°C) and hypotension requiring noradrenaline 0.15 mcg/kg/min. Blood tests show WBC 22 × 10⁹/L, bilirubin 85 μmol/L, and lactate 4.5 mmol/L. Blood cultures are pending. CXR shows no acute changes. A bedside abdominal ultrasound is performed.

Question: a) List four ultrasound features that would support a diagnosis of acalculous cholecystitis (4 marks) b) Using the Tokyo Guidelines 2018, classify the severity of acute cholecystitis in this patient and justify your grading (4 marks) c) Describe the pathophysiology of acalculous cholecystitis in this clinical context (4 marks) d) Outline your initial management, including antibiotic selection and source control strategy (8 marks)

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Model Answer:

a) Ultrasound features supporting AAC diagnosis (4 marks)

b) Tokyo Guidelines 2018 Severity Classification (4 marks)

Classification: Grade III (Severe) (2 marks)

Justification: Grade III is defined by acute cholecystitis with organ dysfunction in any system. This patient has:

• Cardiovascular dysfunction: Hypotension requiring noradrenaline (any dose of noradrenaline meets criterion)
• Potentially hepatic dysfunction: Elevated bilirubin (if INR >1.5)
• Elevated lactate: Suggests tissue hypoperfusion

(2 marks for correct classification with any valid justification)

c) Pathophysiology in this context (4 marks)

The pathophysiology of AAC involves three interconnected mechanisms:

1. Bile Stasis (1 mark)

• TPN provides no enteral stimulation → No CCK release from duodenal I-cells
• Absent CCK → Gallbladder hypomotility and atony
• Bile becomes concentrated and toxic (lysophosphatidylcholine)

2. Ischemia-Reperfusion Injury (1.5 marks)

• Post-AAA repair: Major haemorrhage, prolonged hypotension, massive transfusion
• Splanchnic hypoperfusion during and after surgery
• Cystic artery is an end-artery with limited collaterals
• Ischaemic injury to gallbladder mucosa → Reperfusion generates ROS

3. Systemic Inflammatory Response (1.5 marks)

• Major surgery triggers SIRS (TNF-α, IL-1β, IL-6)
• Endothelial activation and glycocalyx injury
• Microvascular thrombosis → Further ischemia
• Complement activation and coagulation cascade

d) Initial Management (8 marks)

Resuscitation (2 marks)

• Fluid resuscitation: 30 mL/kg balanced crystalloid within 3 hours
• Vasopressor optimisation: Noradrenaline first-line, target MAP ≥65 mmHg
• Consider vasopressin as adjunct if escalating noradrenaline
• Serial lactate monitoring (every 4-6 hours)

Antibiotic Selection (3 marks)

• Broad-spectrum coverage within 1 hour of sepsis recognition
• Recommended regimen: Piperacillin-tazobactam 4.5 g IV 6-hourly (extended infusion)
  • OR Meropenem 1 g IV 8-hourly if ESBL risk/colonisation
• Covers enteric gram-negatives (E. coli, Klebsiella, Enterobacter) and anaerobes (Bacteroides)
• Consider adding vancomycin if MRSA/Enterococcus risk
• Duration: 4 days after adequate source control (STOP-IT trial)

Source Control Strategy (3 marks)

• Source control within 12 hours is critical
• Assessment of fitness for surgery:
  • If responding to resuscitation and can tolerate GA → Laparoscopic cholecystectomy (preferred per CHOCOLATE trial)
  • If unstable/unfit for GA → Percutaneous cholecystostomy
• Given recent major surgery and current instability, percutaneous cholecystostomy is likely appropriate initial approach
• If PC placed, plan for interval cholecystectomy when stable (6-8 weeks)
• If evidence of gangrenous/perforated cholecystitis on imaging, surgical cholecystectomy is required despite risk

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Examiner Tips:

• Candidates often forget to grade severity using TG18 - practice the criteria
• Antibiotic selection should be specific (drug, dose, frequency) not just "broad-spectrum"
• Source control decision-making should be explicit about patient fitness assessment
• Remember STOP-IT trial for antibiotic duration (4 days after source control)

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SAQ 2: Complications and Special Populations (20 marks)

Stem: A 48-year-old woman with poorly controlled type 2 diabetes (HbA1c 12%) is day 3 post-cholecystostomy for acalculous cholecystitis. Despite drainage (100 mL bile-stained fluid initially, now minimal output), she remains febrile with worsening abdominal pain. Repeat CT shows gas within the gallbladder wall and lumen.

Question: a) What is the likely diagnosis and what are the key risk factors for this complication? (4 marks) b) Describe the microbiological considerations including likely pathogens and antibiotic modification (4 marks) c) Outline the definitive management of this condition (4 marks) d) The patient's husband is an Aboriginal Elder from a remote community. Discuss the specific cultural and practical considerations for managing this patient's care (8 marks)

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Model Answer:

a) Diagnosis and Risk Factors (4 marks)

Diagnosis: Emphysematous Cholecystitis (EC) (1 mark)

This is a severe, life-threatening variant of acute cholecystitis characterised by gas in the gallbladder wall or lumen, caused by gas-forming organisms.

Key Risk Factors (3 marks, 1 each for 3 factors):

b) Microbiological Considerations (4 marks)

Likely Pathogens (2 marks):

Often polymicrobial (gram-negatives + anaerobes)

Antibiotic Modification (2 marks):

• Current regimen should be reviewed for adequate coverage
• Recommend: Meropenem 1 g IV 8-hourly (broad gram-negative and anaerobic coverage)
  • OR Piperacillin-tazobactam 4.5 g IV 6-hourly (extended infusion)
• Add Metronidazole 500 mg IV 12-hourly if using a non-carbapenem backbone for enhanced anaerobic coverage
• Ensure adequate clostridial coverage
• Obtain bile cultures (if not already done) and blood cultures
• Surgical specimens for culture and sensitivity

c) Definitive Management (4 marks)

Emphysematous cholecystitis is a SURGICAL EMERGENCY (1 mark)

Surgical Management (3 marks):

1. Urgent cholecystectomy is mandatory - Percutaneous drainage alone is insufficient
2. Open cholecystectomy may be required (high conversion rate from laparoscopic in EC)
3. Peritoneal lavage if peritonitis present
4. May require damage control surgery with temporary abdominal closure if unstable
5. Cholecystostomy already failed - catheter output minimal suggests non-draining or non-viable gallbladder
6. Post-operative ICU care with ongoing resuscitation

Pre-operative Optimisation:

• Blood glucose control (target 8-12 mmol/L peri-operatively)
• Correct coagulopathy
• Crossmatch blood available
• Discuss with surgical team urgently

d) Cultural and Practical Considerations (8 marks)

Cultural Safety (4 marks):

1. Involve Aboriginal Health Worker (AHW) or Aboriginal Liaison Officer (ALO) (1 mark)

   • Essential for communication and cultural support
   • Facilitate family meetings
   • Assist with interpreter services if needed

2. Respect for family involvement and kinship structures (1 mark)

   • Husband is an Elder - his views carry significant weight in community
   • Extended family may need to be involved in major decisions
   • Allow time for family to travel from remote community
   • Collective decision-making rather than individual autonomy model

3. Communication considerations (1 mark)

   • Clear, jargon-free language
   • Visual aids if available
   • Check understanding with teach-back
   • May prefer same-gender care providers for some aspects
   • Avoid direct eye contact if culturally appropriate

4. Spiritual and cultural needs (1 mark)

   • Offer access to cultural and spiritual support
   • Consider Sorry Business or other cultural obligations
   • May have preferences regarding blood products, surgery
   • Ensure body integrity considerations are discussed if poor prognosis

Practical Considerations (4 marks):

5. Prognosis and goals of care discussion (1 mark)

   • EC mortality 15-25%; higher with diabetes, delayed surgery
   • Must have clear discussion with family about severity
   • Involve AHW/ALO in family meeting
   • Allow time for family consensus

6. Remote community considerations (1 mark)

   • Family may need assistance with travel and accommodation
   • Liaise with social work for support services
   • Consider family's need to return to community for obligations

7. Follow-up and discharge planning (1 mark)

   • Early planning for return to community
   • Involve local Aboriginal Community Controlled Health Organisation (ACCHO)
   • Ensure follow-up accessible (telehealth if needed)
   • Diabetic management plan for ongoing care

8. Health literacy and education (1 mark)

   • Ensure patient and family understand diabetes management
   • Provide culturally appropriate health information
   • Link with diabetes educator with Indigenous health experience
   • Consider long-term health implications for community

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Examiner Tips:

• Emphysematous cholecystitis requires surgery - PC alone is not sufficient
• Cultural safety questions are increasingly examined - know the key principles
• Use specific terminology (AHW, ALO, ACCHO) to demonstrate knowledge
• Practical considerations should address the full patient journey, not just acute care

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11. Hot Cases

Hot Case 1: Post-Cardiac Surgery Sepsis

Opening Statement: "This is Mr. Thompson, a 68-year-old man, day 7 post-coronary artery bypass grafting. He was extubated on day 2 but re-intubated yesterday for respiratory failure and hypotension. He is currently on noradrenaline 0.2 mcg/kg/min, mechanically ventilated on SIMV, with an FiO₂ of 0.5. He has been on TPN since day 3 due to ileus. The surgical team has asked for ICU input regarding unexplained sepsis."

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Systematic Approach:

A - Airway: ETT in situ, secured, appropriate position

B - Breathing:

• Ventilated: SIMV, Vt 450 mL, RR 16, PEEP 8, FiO₂ 0.5
• Bilateral air entry, no added sounds
• SpO₂ 94%, P/F ratio 188 (300/0.5 × 0.94 ≈ calculating)

C - Circulation:

• Noradrenaline 0.2 mcg/kg/min
• HR 110, MAP 68
• Warm peripheries, CRT 3 seconds
• CVP 12, ScvO₂ 65%
• Review sternotomy wound: clean, no dehiscence

D - Disability:

• Sedated: propofol 50 mcg/kg/min, fentanyl 50 mcg/hr
• RASS -2, pupils 3mm equal and reactive

E - Exposure:

• Temperature 38.8°C
• Abdominal examination: soft, mild RUQ fullness, no peritonism (limited by sedation)
• No rashes, IV sites clean

Investigations Review:

• FBC: WBC 24 × 10⁹/L, Hb 85 g/L, Plt 120 × 10⁹/L
• UEC: Cr 180 μmol/L (baseline 95), urea 15
• LFTs: Bili 75 μmol/L, ALP 320 U/L, GGT 280 U/L, ALT 65 U/L
• CRP 280 mg/L, Procalcitonin 8.5 ng/mL
• Lactate 3.8 mmol/L
• Blood cultures: Pending (drawn this morning)
• CXR: No consolidation, lines in situ
• Abdominal USS (performed this morning): Gallbladder distended (5.5 cm), wall thickening 4.5 mm, pericholecystic fluid present, no stones seen

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Candidate Presentation (2 minutes):

"This is a 68-year-old man, day 7 post-CABG, who has developed septic shock with Grade III acute cholecystitis based on Tokyo Guidelines 2018.

Key features supporting this diagnosis:

• Classic risk factors: Post-cardiac surgery, prolonged TPN, mechanical ventilation
• Systemic inflammatory response with organ dysfunction: Cardiovascular (vasopressor-dependent), Renal (AKI), Haematological (thrombocytopenia)
• Cholestatic LFT pattern
• Ultrasound findings consistent with acute cholecystitis without calculi

Given the absence of gallstones in a high-risk patient with typical imaging findings, this is acalculous cholecystitis, which carries a mortality of 30-50% in the ICU setting.

My immediate priorities are:

1. Optimise resuscitation - Fluid assessment, vasopressor titration
2. Ensure broad-spectrum antibiotics are prescribed
3. Urgent source control - Decision between percutaneous cholecystostomy versus surgical cholecystectomy
4. CT abdomen to assess for gangrenous or complicated disease"

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Examiner Questions and Model Answers:

Q1: What is the pathophysiology of acalculous cholecystitis in this patient?

A1: "The pathophysiology involves a triad of factors converging in this post-cardiac surgery patient:

1. Bile stasis: TPN has been administered since day 3, providing no enteral stimulation. Without nutrients in the duodenum, there is no CCK release from I-cells, leading to gallbladder hypomotility and concentrated, cytotoxic bile.

2. Ischemia-reperfusion injury: During and after CABG with cardiopulmonary bypass, there is reduced splanchnic perfusion. The cystic artery is an end-artery with limited collaterals, making the gallbladder vulnerable to ischaemic injury. Reperfusion generates reactive oxygen species causing further mucosal damage.

3. Systemic inflammatory response: Cardiac surgery with CPB triggers a significant SIRS response. Elevated cytokines (TNF-α, IL-1β, IL-6) cause endothelial activation, glycocalyx injury, and microvascular thrombosis, exacerbating gallbladder wall injury.

These factors combine to cause mucosal necrosis, secondary bacterial infection, and potentially rapid progression to gangrene - which occurs in 50% of AAC cases compared to only 2-5% of calculous cholecystitis."

Q2: What source control option would you recommend for this patient?

A2: "The choice of source control depends on the patient's fitness for surgery and the presence of complicated disease.

For this patient, I would recommend:

1. Immediate CT abdomen with contrast to assess for gangrenous changes, perforation, or other complications

2. If no evidence of gangrene/perforation:

   • Given his post-cardiac surgery status and current instability, percutaneous cholecystostomy would be a reasonable initial approach
   • This can be performed under ultrasound or CT guidance at bedside or in interventional radiology
   • Expected response: Clinical improvement within 24-48 hours

3. If gangrenous or perforated:

   • Surgical cholecystectomy is required despite the risks
   • Involve cardiothoracic surgery for anaesthetic considerations
   • May require open approach

4. CHOCOLATE trial context: This trial showed laparoscopic cholecystectomy was superior to PC in high-risk but operable patients. However, this patient's recent sternotomy, current haemodynamic instability, and cardiac surgery context make him truly high-risk for general anaesthesia currently. I would discuss with hepatobiliary surgery and cardiac surgery jointly.

5. If PC performed and successful: Plan interval cholecystectomy at 6-8 weeks when recovered."

Q3: The CT shows no evidence of gangrenous changes. The patient undergoes successful percutaneous cholecystostomy with 80 mL bile drained. 48 hours later, he remains febrile and vasopressor-dependent. What are your differentials?

A3: "Failure to respond to cholecystostomy at 48 hours requires systematic evaluation:

Related to the biliary intervention:

1. Gangrenous cholecystitis (may have been underestimated on initial CT)
2. Catheter malposition or blockage (check output, consider cholecystogram)
3. Pericholecystic abscess requiring additional drainage
4. Ascending cholangitis with CBD involvement

Alternative sources of sepsis: 5. Nosocomial pneumonia (VAP - day 10 of ventilation) 6. Central line-associated bloodstream infection (CLABSI) 7. Urinary tract infection 8. Sternal wound infection or mediastinitis 9. C. difficile colitis 10. Deep surgical site infection

My approach:

1. Repeat CT abdomen to assess gallbladder and catheter position
2. Review microbiology: Blood cultures, bile cultures, sputum, urine
3. Line surveillance: Consider line change over wire and tip culture
4. Chest assessment: Bronchoscopy and BAL for VAP if indicated
5. Sternal wound examination and potentially chest CT
6. C. diff testing if diarrhoea
7. Consider surgical cholecystectomy if biliary source persists"

Q4: What antibiotics would you prescribe and for how long?

A4: "For healthcare-associated biliary sepsis with Grade III severity:

Initial regimen:

• Piperacillin-tazobactam 4.5 g IV 6-hourly as extended infusion over 4 hours
  • OR Meropenem 1 g IV 8-hourly if ESBL colonisation or prior exposure
• Provides coverage for Enterobacteriaceae, Pseudomonas, Enterococcus, and anaerobes

Additional considerations for this patient:

• Review colonisation status from admission swabs
• If MRSA colonised: Add vancomycin 25-30 mg/kg load, then AUC-guided dosing
• If candida risk (prolonged ICU, prior antibiotics, TPN): Consider fluconazole 400 mg daily

Duration:

• Based on the STOP-IT trial: 4 days after adequate source control
• If cholecystostomy successful: 4 days from drainage
• If surgical cholecystectomy performed with no extension beyond gallbladder: Can discontinue at 24 hours post-operatively
• If inadequate source control: Continue until definitive management achieved

De-escalation:

• Narrow based on bile and blood culture results
• Review at 48-72 hours"

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Hot Case 2: Burns Patient with Unexplained Deterioration

Opening Statement: "This is Ms. Williams, a 42-year-old Aboriginal woman from a remote community, who sustained 45% TBSA mixed-depth burns in a house fire 12 days ago. She has been in the Burns ICU, mechanically ventilated, and has undergone two debridement and grafting procedures. She was progressing well until 48 hours ago when she developed increasing vasopressor requirements and rising inflammatory markers. Her family, including community Elders, have arrived and are very anxious."

---

Systematic Approach:

A - Airway: ETT in situ, no inhalation injury on admission bronchoscopy

B - Breathing:

• SIMV: Vt 480 mL, RR 18, PEEP 10, FiO₂ 0.6
• Bilateral air entry, scattered crackles
• SpO₂ 92%, P/F ratio 153

C - Circulation:

• Noradrenaline 0.35 mcg/kg/min (increased from 0.1 over 48 hours)
• HR 125, MAP 62
• Warm, bounding pulses, CRT <2 seconds
• Lactate trending up: 2.8 → 3.5 → 4.2 mmol/L

D - Disability:

• Sedated: Fentanyl 100 mcg/hr, midazolam 5 mg/hr
• RASS -3, unable to assess GCS

E - Exposure:

• Temperature 39.2°C
• Burn wounds: Grafts healing well, donor sites clean
• Abdomen: Distended, RUQ tenderness to palpation (through dressings)
• Has been on TPN since day 5 (ileus post-grafting)

Investigations:

• WBC: 28 × 10⁹/L (baseline elevated at 18)
• CRP: 380 mg/L (was 150 mg/L 2 days ago)
• Procalcitonin: 12.5 ng/mL
• LFTs: Bili 95 μmol/L, ALP 410 U/L, ALT 85 U/L
• Lactate: 4.2 mmol/L
• Blood cultures: Pending
• Wound swabs: No new organisms
• Abdominal USS: Gallbladder distended (6 cm), wall thickening 5.2 mm, pericholecystic fluid, sludge present, no stones

---

Candidate Presentation:

"This is a 42-year-old Aboriginal woman with severe burns who has developed septic shock with a likely intra-abdominal source. Based on the ultrasound findings and clinical picture, I am concerned about acalculous cholecystitis.

She is a classic high-risk patient: 45% TBSA burns, prolonged TPN for 12 days, multiple surgeries, and immobilisation. The Tokyo Guidelines 2018 Grade III criteria are met with cardiovascular dysfunction.

My immediate priorities are:

1. Optimise resuscitation
2. Broad-spectrum antibiotics (covering biliary pathogens)
3. CT abdomen to exclude gangrenous or complicated disease
4. Source control planning - likely percutaneous cholecystostomy initially
5. Engage Aboriginal Health Worker for family support and communication

Given her Indigenous background and the presence of family and Elders, I need to involve Aboriginal Health Worker immediately and ensure culturally safe communication about her condition and prognosis."

---

Examiner Questions and Model Answers:

Q1: The family are very anxious and want to know what is wrong and what the prognosis is. How would you approach this conversation?

A1: "This is a challenging communication scenario requiring cultural sensitivity.

Preparation:

1. Involve Aboriginal Health Worker (AHW) or Aboriginal Liaison Officer (ALO) to co-facilitate the discussion
2. Identify the key decision-makers (may include Elders, not just immediate family)
3. Arrange a private, comfortable space
4. Allow adequate time - do not rush
5. Ensure interpreter available if English is not first language

The conversation:

1. Introduce myself and the AHW, acknowledge the Elders and family
2. Ask how much they already understand about her condition
3. Deliver information in clear, simple language, avoiding medical jargon
4. Explain she has an infection in the gallbladder (the bile bag) that can happen after severe burns
5. Use visual aids if helpful (diagrams, pointing to anatomy)
6. Explain we need to drain the infection and give strong antibiotics
7. Be honest about severity: 'She is very unwell. This is a serious infection on top of her burns. We will do everything we can.'

Prognosis discussion:

• AAC in burns carries 40% mortality, higher with septic shock
• Present honestly but with hope: 'We are very concerned, but we are doing everything to treat this'
• Allow time for questions
• Offer to explain again or to more family members

Cultural considerations:

• Avoid direct eye contact if culturally appropriate
• Allow pauses - silence is part of communication
• Ask if there are cultural or spiritual needs we can support
• Offer access to cultural and spiritual care
• Check understanding using teach-back method

Next steps:

• Plan to update family regularly (at least daily, more if clinical changes)
• Involve AHW in ongoing communication
• Ask about preferences for how to receive bad news if things change"

Q2: CT shows gallbladder wall thickening with possible mucosal sloughing but no perforation. What is your interpretation and management?

A2: "The CT findings of mucosal sloughing suggest early gangrenous changes within the gallbladder. This is a concerning finding that indicates transmural ischaemic injury.

Interpretation:

• Gangrenous cholecystitis developing (or already established)
• Higher mortality than simple AAC (15-25%)
• May progress to perforation
• Percutaneous drainage alone may be insufficient

Management decision: Given gangrenous changes, I would recommend surgical cholecystectomy rather than percutaneous cholecystostomy alone.

However, there are competing considerations:

1. She is currently unstable (high vasopressor requirement)
2. She has ongoing burns requiring future grafting
3. Open abdominal surgery adds significant physiological stress

My approach:

1. Urgent surgical consultation - hepatobiliary and burns teams together
2. Intensive resuscitation to optimise for surgery
3. Aim for surgery within 6-12 hours if possible
4. Laparoscopic approach if achievable, with low threshold for conversion
5. If truly too unstable for any surgery, PC as bridge (with explicit plan for early surgery when stabilised)
6. Communicate with family about need for surgery and risks

Post-operative planning:

• ICU post-operatively for ongoing resuscitation
• May need to delay next grafting procedure
• Coordinate with burns team for overall plan"

Q3: What specific Aboriginal health considerations apply to this patient's care?

A3: "There are several important considerations:

Cultural safety:

1. Aboriginal Health Worker (AHW) or Aboriginal Liaison Officer (ALO) involvement is essential
2. Family-centred decision-making - involve Elders and extended family
3. Clear, jargon-free communication with time for questions
4. May prefer same-gender healthcare providers for personal care
5. Respect for cultural practices and obligations

Health literacy:

1. Use plain language and visual aids
2. Check understanding with teach-back
3. Written information may be less effective - prefer verbal and visual

Practical considerations:

1. Family have travelled from remote community - need accommodation support
2. Social work involvement for family support
3. May be significant Sorry Business or other cultural obligations
4. Allow time for family consensus on major decisions

Health disparities context:

1. Higher rates of diabetes, CVD, renal disease in Indigenous populations
2. May have had less access to healthcare prior to this event
3. Distrust of healthcare system due to historical trauma
4. Important to build trust through respectful, culturally safe care

Discharge and follow-up planning:

1. Start early given complexity and remote location
2. Involve local ACCHO (Aboriginal Community Controlled Health Organisation)
3. Consider telehealth for follow-up
4. Link with Indigenous-specific services for burns rehabilitation
5. Ensure culturally appropriate diabetes education if needed

Prognosis discussions:

1. May need to have multiple conversations as family arrives
2. Allow time for community to be informed
3. Be prepared for questions about returning to Country if prognosis poor
4. Offer cultural and spiritual support"

Q4: She undergoes successful laparoscopic cholecystectomy. Histology confirms gangrenous cholecystitis. Post-operatively she improves. What is your antibiotic duration and discharge planning?

A4: "Antibiotic duration: Based on SIS guidelines and STOP-IT trial:

• Gangrenous cholecystitis with successful surgical removal = 4 days post-operatively
• The source has been completely removed (cholecystectomy, not drainage)
• Do not extend antibiotics for persistent fever/leukocytosis if resolving trend
• De-escalate to narrowest spectrum based on cultures

Discharge planning:

1. Medical:

   • Continue burns care and rehabilitation
   • Plan remaining grafting procedures when fully recovered
   • Diabetes screening/management if applicable
   • VTE prophylaxis continuation

2. Remote community considerations:

   • Prolonged inpatient stay likely for burns care
   • When ready for discharge, liaise with remote clinic and RFDS
   • Telehealth follow-up for surgical review
   • Written discharge summary to remote clinic and ACCHO
   • Consider step-down care closer to home before final discharge

3. Cultural considerations:

   • Discuss timeline for return to community with family
   • Ensure family can return home during prolonged admission if needed
   • Cultural support throughout rehabilitation phase
   • Involve AHW in discharge planning discussions

4. Follow-up:

   • Burns clinic review (may be via telehealth)
   • Surgical follow-up (telehealth appropriate)
   • GP/ACCHO review in community
   • Dietitian follow-up if nutritional issues
   • Mental health screening (PTSD, adjustment) - culturally appropriate service"

---

Hot Case 3: Elderly Patient with Diagnostic Dilemma

Opening Statement: "This is Mr. Chen, an 82-year-old man who was admitted to ICU 5 days ago following emergency repair of a perforated duodenal ulcer. He has a background of type 2 diabetes, hypertension, and mild cognitive impairment. He was extubated on day 3 but has become progressively confused over the past 48 hours with low-grade fevers. He is currently on a ward-level oxygen requirement. The surgical team has asked for ICU review regarding possible delirium versus sepsis."

---

Brief Approach Points:

• Multiple competing diagnoses: Post-operative delirium, sepsis (AAC, pneumonia, UTI, wound), anastomotic leak, medication effect
• Elderly patients have atypical presentations of AAC
• Cognitive impairment makes history and examination challenging
• Tokyo Guidelines may be less reliable (vague symptoms, baseline inflammation)
• Lower threshold for imaging

Key Teaching Points from this case:

1. AAC in elderly may present with confusion as predominant feature
2. Murphy's sign unreliable even in awake elderly patients
3. Multiple sources of sepsis to consider post-abdominal surgery
4. Goals of care discussion important given age and baseline function
5. Family involvement in decision-making

---

12. Viva Scenarios

Viva 1: Pathophysiology and Diagnosis

Examiner: "Tell me about the pathophysiology of acalculous cholecystitis in critically ill patients."

Candidate: "Acalculous cholecystitis results from the convergence of three pathophysiological mechanisms in critically ill patients:

1. Bile Stasis Critically ill patients are often fasted or on TPN. Without enteral nutrients, there is no cholecystokinin release from duodenal I-cells. CCK normally stimulates gallbladder contraction via CCK-1 receptors. Without this stimulation, the gallbladder becomes atonic, and bile becomes concentrated and cytotoxic. Lysophosphatidylcholine, derived from bile phospholipids, directly injures the gallbladder mucosa.

2. Ischemia-Reperfusion Injury Shock states, vasopressor use, and low cardiac output cause splanchnic hypoperfusion. The gallbladder's cystic artery is an end-artery with limited collateral supply, making it vulnerable to ischaemic injury. The mucosa is most susceptible. Reperfusion generates reactive oxygen species, causing further injury.

3. Systemic Inflammatory Response Sepsis, major surgery, and trauma trigger SIRS with elevated TNF-α, IL-1β, and IL-6. These cytokines cause endothelial activation, glycocalyx degradation, and increased vascular permeability. Microvascular thrombosis worsens ischaemia. Complement and coagulation cascades contribute to tissue injury.

These factors combine to cause mucosal necrosis, oedema, and secondary bacterial infection. This explains why AAC progresses to gangrene in 50% of cases compared to only 2-5% in calculous cholecystitis."

Examiner: "What imaging modality would you choose first and what are its limitations in ICU?"

Candidate: "I would choose bedside ultrasound as the first-line imaging modality.

Advantages:

• Portable and can be performed at the bedside
• No radiation or contrast required
• Real-time assessment
• Can assess other abdominal pathology simultaneously

Diagnostic criteria on ultrasound:

• Gallbladder wall thickening >3.5 mm
• Pericholecystic fluid
• Gallbladder distension >5 cm short axis
• Absence of gallstones
• Gallbladder sludge
• Sonographic Murphy's sign (if assessable)

Limitations in ICU:

• Sensitivity only 50-70% in critically ill patients
• Specificity 80-90%

Specific limitations:

1. Sonographic Murphy's sign unreliable in sedated patients
2. Wall thickening may be due to hypoalbuminemia, ascites, or hepatitis
3. Sludge is common in prolonged fasting and is non-specific
4. Bowel gas may obscure views
5. Patient positioning difficult (wounds, lines, dressings)
6. Operator-dependent

If ultrasound equivocal, I would proceed to CT with contrast, which has sensitivity >90% for complicated disease and can identify gangrenous changes, perforation, or alternative diagnoses."

Examiner: "What about HIDA scan?"

Candidate: "HIDA scan or cholescintigraphy has a high false-positive rate in ICU patients, up to 30-50%, and I would not recommend it as first-line.

The principle is that Tc-99m-HIDA is taken up by hepatocytes and excreted into bile. Non-visualisation of the gallbladder at 4 hours indicates cystic duct obstruction.

However, in ICU patients:

• TPN reduces CCK stimulation, causing gallbladder atony and non-visualisation without disease
• Prolonged fasting has the same effect
• Hepatic dysfunction reduces uptake and excretion
• Opioids cause Sphincter of Oddi spasm
• Critical illness affects multiple factors

Additionally, HIDA requires patient transport, takes 4+ hours to complete, and cannot assess for complications like gangrene or perforation.

Therefore, ultrasound and CT are preferred in the ICU setting."

---

Viva 2: Tokyo Guidelines and Severity Assessment

Examiner: "Explain the Tokyo Guidelines 2018 severity grading for acute cholecystitis."

Candidate: "The Tokyo Guidelines 2018, or TG18, provide a three-tier severity grading system based on the presence of local inflammation, systemic inflammation, and organ dysfunction.

Grade I - Mild: Acute cholecystitis that does not meet criteria for Grade II or III. The patient is otherwise healthy with no organ dysfunction and limited local inflammation.

Grade II - Moderate: Presence of any one of:

• Elevated WBC >18,000/mm³
• Palpable tender mass in right upper quadrant
• Duration of symptoms >72 hours
• Marked local inflammation: gangrenous cholecystitis, pericholecystic abscess, biliary peritonitis, or emphysematous cholecystitis

Grade III - Severe: Associated with organ dysfunction in any system:

• Cardiovascular: Hypotension requiring dopamine ≥5 mcg/kg/min or any dose of noradrenaline
• Neurological: Decreased level of consciousness
• Respiratory: PaO₂/FiO₂ ratio <300
• Renal: Oliguria or creatinine >177 μmol/L
• Hepatic: INR >1.5
• Haematological: Platelets <100,000/mm³

ICU Relevance: Most ICU patients with AAC are Grade III by definition because organ support is common. This is important because Grade III patients require gallbladder drainage and organ support as the primary initial management, with surgery reserved for those with complications or failure to improve."

Examiner: "A patient meets Grade III criteria due to vasopressor requirement. Does this mean they cannot have surgery?"

Candidate: "No, Grade III does not preclude surgery. The TG18 flowcharts recommend initial resuscitation, antibiotics, and consideration of biliary drainage in Grade III patients, but surgery remains an option.

The key decision points are:

1. After initial resuscitation, reassess: Can the patient tolerate general anaesthesia?

2. If stable after resuscitation: Surgery (laparoscopic cholecystectomy) may be superior to drainage. The CHOCOLATE trial showed better outcomes with surgery in high-risk but operable patients.

3. If unstable despite resuscitation: Percutaneous cholecystostomy is appropriate as a bridge.

4. If gangrenous or perforated: Surgical intervention is usually required regardless of stability, though damage control principles may apply.

The grading helps prognostication and guides initial management intensity, but it does not determine definitive source control modality. That decision requires individual patient assessment of surgical risk, anatomical considerations, and clinical trajectory."

---

Viva 3: Source Control Options

Examiner: "Compare percutaneous cholecystostomy and laparoscopic cholecystectomy for acute cholecystitis in ICU patients."

Candidate: "These are the two main source control options, each with distinct advantages and indications.

Percutaneous Cholecystostomy (PC):

Technique: Ultrasound or CT-guided drainage, typically transhepatic approach, using Seldinger technique with 8-12 Fr pigtail catheter.

Advantages:

• Can be performed at bedside or in IR suite
• Avoids general anaesthesia
• Lower immediate procedural risk
• Rapid symptom relief in 80-90% within 24-48 hours

Disadvantages:

• Does not remove the gallbladder
• 30-50% recurrence if not followed by cholecystectomy
• Catheter complications: dislodgement (5-10%), bile leak, blockage
• Requires interval cholecystectomy in fit patients

Laparoscopic Cholecystectomy:

Advantages:

• Definitive treatment
• Removes source completely
• Lower recurrence and re-intervention rates
• CHOCOLATE trial showed superior outcomes in high-risk but operable patients

Disadvantages:

• Requires general anaesthesia
• Higher immediate procedural risk in unstable patients
• 10-30% conversion to open in acute setting
• Operative mortality 0.5-2% in high-risk patients

CHOCOLATE Trial Evidence (PMID: 30262261):

• 142 high-risk patients (APACHE II 7-14) randomised to LC vs PC
• Major complications: 12% surgery vs 44% drainage
• Recurrence: 5% vs 53%
• Trial stopped early for benefit of surgery
• Conclusion: LC superior if patient can tolerate surgery"

Examiner: "When would you definitively choose one over the other?"

Candidate: "Definite indications for cholecystectomy:

1. Gangrenous cholecystitis (confirmed or suspected)
2. Emphysematous cholecystitis
3. Gallbladder perforation
4. Patient fit for surgery after resuscitation (CHOCOLATE trial)
5. Failed percutaneous drainage

Definite indications for percutaneous cholecystostomy:

1. Truly unfit for any general anaesthesia (severe cardiac/respiratory failure, ongoing CPR/ECMO)
2. Extreme coagulopathy precluding surgery
3. Prohibitive surgical risk (e.g., hostile abdomen, cirrhosis with portal hypertension)
4. Bridge to interval surgery in very high-risk patients
5. Patient/family preference for non-operative management (after informed discussion)

Grey zone requiring clinical judgement:

• Recent major surgery (e.g., cardiac, abdominal)
• Multiple comorbidities but not absolute contraindications
• Borderline haemodynamic stability

In these cases, multidisciplinary discussion (ICU, surgery, interventional radiology) is essential."

---

Viva 4: Antibiotic Therapy

Examiner: "What antibiotic regimen would you use for acalculous cholecystitis in ICU, and how long would you continue treatment?"

Candidate: "For acute acalculous cholecystitis in the ICU setting, I would use empiric broad-spectrum antibiotics covering enteric gram-negatives and anaerobes.

Recommended regimen (Australian eTG):

Healthcare-associated/Severe:

• Piperacillin-tazobactam 4.5 g IV 6-hourly (extended infusion over 4 hours)
• OR Meropenem 1 g IV 8-hourly (extended infusion over 3 hours) if ESBL colonised

Additional coverage:

• Vancomycin if MRSA or Enterococcus risk
• Fluconazole or anidulafungin if candida risk (prolonged ICU, prior antibiotics, TPN)

Target organisms:

• Gram-negatives: E. coli, Klebsiella, Enterobacter, Pseudomonas
• Gram-positives: Enterococcus
• Anaerobes: Bacteroides fragilis, Clostridium

Duration: Based on the STOP-IT trial (PMID: 25992746) and SIS guidelines (PMID: 28085573):

• After adequate source control: 4 days (96 hours)
• Successful cholecystectomy without extension: ≤24 hours post-operatively
• Inadequate source control: Continue until definitive management

Key points:

• 'Adequate source control' means infected focus removed or drained
• Do NOT extend for persistent fever/leukocytosis if source controlled
• Investigate for other sources if not improving
• De-escalate based on culture results"

Examiner: "What is the evidence for the 4-day duration?"

Candidate: "The STOP-IT trial, published in NEJM in 2015, was a multicentre randomised controlled trial of 518 patients with complicated intra-abdominal infection who had adequate source control.

Patients were randomised to:

• Fixed 4-day antibiotic course
• Standard therapy (physician discretion, mean 8 days)

Results:

• Composite outcome (surgical site infection, recurrent abscess, death within 30 days): 21.8% vs 22.3% (non-inferior)
• No difference in mortality or infectious complications
• 4-day group had less C. difficile infection

Conclusion: 4 days of antibiotics after adequate source control is non-inferior to longer courses.

Clinical implication: Stop antibiotics at 4 days post-source control, regardless of persistent fever or leukocytosis. Continuing antibiotics does not improve outcomes but increases CDI risk and promotes resistance."

---

Viva 5: Complications

Examiner: "Tell me about gangrenous cholecystitis - risk factors, diagnosis, and management."

Candidate: "Gangrenous cholecystitis is a severe complication characterised by necrosis of the gallbladder wall due to ischaemia and progressive inflammation.

Epidemiology:

• Occurs in 40-50% of acalculous cholecystitis (vs 2-5% of calculous)
• Mortality 15-25%

Risk factors (PMID: 25414341, 30336625):

• Age >51 years
• Male sex
• Diabetes mellitus
• Elevated WBC >17,000/mm³
• Elevated CRP
• Cardiovascular disease
• Delayed presentation (>72 hours)

Clinical features:

• Paradoxical improvement in pain (nerve necrosis)
• High fever, tachycardia
• Marked leukocytosis
• Rapid clinical deterioration

Imaging diagnosis (CT):

• Irregular or absent gallbladder wall enhancement (most specific)
• Intramural haemorrhage
• Membranous structures in lumen
• Pericholecystic abscess
• Gas in wall (if emphysematous component)

Management:

• SURGICAL EMERGENCY - Cholecystectomy required
• Percutaneous drainage alone is insufficient
• Open approach may be necessary
• Damage control surgery if patient unstable (cholecystostomy tube, plan for second-look)
• Broad-spectrum antibiotics
• ICU post-operative care"

Examiner: "What about emphysematous cholecystitis?"

Candidate: "Emphysematous cholecystitis is a life-threatening variant characterised by gas in the gallbladder wall or lumen, caused by gas-forming organisms.

Epidemiology:

• 1-3% of acute cholecystitis
• More common in AAC than calculous
• Mortality 15-25%

Risk factors (PMID: 17215336):

• Diabetes mellitus (30-50% of cases) - most important
• Male sex (3:1 ratio)
• Vascular disease/atherosclerosis
• Immunosuppression

Pathogens:

• Clostridium perfringens (welchii)
• E. coli
• Klebsiella
• Streptococcus species

Diagnosis:

• Gas visible on plain X-ray, CT, or ultrasound
• CT is most sensitive

Management:

• SURGICAL EMERGENCY
• Urgent cholecystectomy - do not delay
• Broad-spectrum antibiotics with enhanced anaerobic coverage
• Typically requires open approach
• High mortality if delayed"

---

Viva 6: Indigenous Health and Communication

Examiner: "A 55-year-old Aboriginal man from a remote community has developed acalculous cholecystitis post-trauma. His family, including Elders, have arrived. How would you approach communication with this family?"

Candidate: "This requires a culturally safe approach to communication and decision-making.

Preparation:

1. Involve Aboriginal Health Worker (AHW) or Aboriginal Liaison Officer (ALO) to co-facilitate the discussion
2. Identify key decision-makers - may include Elders, not just immediate family
3. Arrange private, comfortable space
4. Allow adequate time
5. Ensure interpreter available if English is not first language

During the conversation:

1. Introduce myself and the AHW, acknowledge the Elders
2. Use clear, simple language without medical jargon
3. Use visual aids or diagrams if helpful
4. Allow time for questions and silence (important in Aboriginal communication)
5. Check understanding with teach-back method
6. Be honest about severity but maintain hope

Cultural considerations:

• Family-centred decision-making - collective approach rather than individual autonomy
• Elders have significant authority in decision-making
• Avoid direct eye contact if culturally appropriate
• Men's and Women's Business may affect who should discuss certain issues
• Allow time for family consensus before major decisions

Practical considerations:

• Family may need accommodation and support if from remote community
• May be Sorry Business or other cultural obligations affecting timing
• Social work involvement for family support
• Consider how to involve remote family who cannot travel

Specific to this scenario:

• Explain the condition in simple terms: 'Infection in the bile bag that happens after serious injuries'
• Explain the treatment: 'We need to drain or remove the infection, and give strong antibiotics'
• Explain prognosis honestly: 'He is very unwell. We will do everything we can, but this is serious.'
• Ask about preferences for receiving bad news and who should be present for difficult conversations"

Examiner: "If the patient's condition deteriorates and prognosis is poor, how would you approach goals of care discussions?"

Candidate: "Goals of care discussions in this context require additional cultural considerations.

Preparation:

1. AHW/ALO essential for this conversation
2. Allow extended family and Elders to be present
3. Ensure adequate time and privacy
4. Check if there are specific cultural protocols for discussing death

During discussion:

1. Be honest but compassionate about prognosis
2. Explain what intensive care can and cannot achieve
3. Ask about the patient's values and what matters to him
4. Ask if there are cultural or spiritual practices that should be observed
5. Discuss options: continued active treatment vs comfort-focused care

Cultural considerations specific to end-of-life:

• Importance of 'returning to Country' - dying on ancestral land may be significant
• May need to arrange transfer to community if patient wishes
• Body integrity beliefs - organ donation discussions require sensitivity
• Extended family and community should be informed
• Ceremonies or rituals may be requested
• Time needed for family to gather

Practical steps:

• Document patient's and family's wishes clearly
• Involve palliative care if appropriate
• Ensure comfort measures are culturally appropriate
• Allow family to stay and participate in care
• Provide private space for family gatherings and ceremonies
• After death, respect cultural practices around the body"

---

13. Interactive Elements

Clinical Decision Algorithm: Suspected AAC in ICU

┌─────────────────────────────────────────────────────────────────┐
│                    SUSPECTED ACALCULOUS CHOLECYSTITIS          │
│                                                                 │
│  Clinical Triggers:                                             │
│  • Unexplained sepsis in high-risk patient                     │
│  • Failure to progress post-major surgery                      │
│  • RUQ tenderness/fullness                                     │
│  • Cholestatic LFT pattern                                     │
└─────────────────────────────────────────────────────────────────┘
                               │
                               ▼
┌─────────────────────────────────────────────────────────────────┐
│                  BEDSIDE ABDOMINAL ULTRASOUND                   │
│                                                                 │
│  AAC Criteria:                                                  │
│  □ Wall thickening >3.5 mm                                     │
│  □ Pericholecystic fluid                                       │
│  □ Gallbladder distension >5 cm                                │
│  □ Absence of gallstones                                       │
│  □ Sludge (non-specific)                                       │
└─────────────────────────────────────────────────────────────────┘
                               │
              ┌────────────────┼────────────────┐
              │                │                │
         POSITIVE          EQUIVOCAL        NEGATIVE
              │                │                │
              ▼                ▼                ▼
┌───────────────────┐ ┌───────────────────┐ ┌───────────────────┐
│ INITIATE TREATMENT│ │   CT ABDOMEN      │ │ CONSIDER OTHER    │
│                   │ │   WITH CONTRAST   │ │ SOURCES OF SEPSIS │
│ • Resuscitation   │ │                   │ │                   │
│ • Antibiotics     │ │ Assess for:       │ │ • Pneumonia       │
│ • Surgery consult │ │ • Gangrenous      │ │ • Line infection  │
│                   │ │ • Emphysematous   │ │ • UTI             │
│                   │ │ • Perforation     │ │ • Wound           │
│                   │ │ • Alternative Dx  │ │ • C. diff         │
└───────────────────┘ └───────────────────┘ └───────────────────┘
              │                │
              └────────┬───────┘
                       │
                       ▼
┌─────────────────────────────────────────────────────────────────┐
│                  TOKYO GUIDELINES 2018 GRADING                  │
│                                                                 │
│  Grade I (Mild): No organ dysfunction, limited inflammation     │
│  Grade II (Moderate): WBC >18k, symptoms >72h, local inflam.   │
│  Grade III (Severe): Organ dysfunction (CV, resp, renal, etc.) │
└─────────────────────────────────────────────────────────────────┘
                       │
                       ▼
┌─────────────────────────────────────────────────────────────────┐
│                    SOURCE CONTROL DECISION                      │
│                                                                 │
│  ┌─────────────────────────┐    ┌─────────────────────────┐    │
│  │   FIT FOR SURGERY?      │    │   COMPLICATED DISEASE?  │    │
│  │                         │    │                         │    │
│  │   □ Haemodynamically    │    │   □ Gangrenous          │    │
│  │     stable on minimal   │    │   □ Emphysematous       │    │
│  │     vasopressors        │    │   □ Perforated          │    │
│  │   □ Can tolerate GA     │    │   □ Abscess             │    │
│  │   □ No prohibitive      │    │                         │    │
│  │     comorbidities       │    │                         │    │
│  └─────────────────────────┘    └─────────────────────────┘    │
└─────────────────────────────────────────────────────────────────┘
                       │
     ┌─────────────────┼─────────────────┐
     │                 │                 │
     ▼                 ▼                 ▼
┌──────────┐    ┌──────────────┐   ┌───────────────┐
│  FIT +   │    │  UNFIT, NO   │   │ COMPLICATED   │
│  UNCOMPLI│    │  COMPLICATED │   │  (GANGRENE/   │
│  CATED   │    │              │   │  EMPHYSEMA/   │
│          │    │              │   │  PERFORATION) │
└──────────┘    └──────────────┘   └───────────────┘
     │                 │                 │
     ▼                 ▼                 ▼
┌──────────┐    ┌──────────────┐   ┌───────────────┐
│  LAP     │    │ PERCUTANEOUS │   │   SURGICAL    │
│  CHOLE   │    │ CHOLECYSTO-  │   │ CHOLECYSTEC-  │
│  (prefer)│    │ STOMY        │   │   TOMY        │
│          │    │              │   │ (open if      │
│ CHOCOLATE│    │ Bridge to    │   │  needed)      │
│ trial    │    │ interval     │   │               │
│ evidence │    │ surgery      │   │ DAMAGE        │
│          │    │              │   │ CONTROL if    │
│          │    │              │   │ unstable      │
└──────────┘    └──────────────┘   └───────────────┘

Diagnostic Imaging Comparison Flowchart

┌─────────────────────────────────────────────────────────────────┐
│               IMAGING MODALITY SELECTION                        │
└─────────────────────────────────────────────────────────────────┘
                               │
                               ▼
┌─────────────────────────────────────────────────────────────────┐
│  ULTRASOUND (First-Line)                                        │
│  ────────────────────────                                       │
│  Sensitivity: 50-70%    Specificity: 80-90%                    │
│                                                                 │
│  ✓ Portable, bedside                                           │
│  ✓ No radiation/contrast                                       │
│  ✓ Real-time assessment                                        │
│  ✗ Operator-dependent                                          │
│  ✗ Limited by bowel gas                                        │
│  ✗ Murphy's sign unreliable if sedated                         │
└─────────────────────────────────────────────────────────────────┘
                               │
                  ┌────────────┴────────────┐
                  │                         │
            DEFINITIVE                 EQUIVOCAL
                  │                         │
                  ▼                         ▼
     ┌─────────────────────┐   ┌─────────────────────────────────┐
     │  Proceed to         │   │  CT ABDOMEN WITH CONTRAST       │
     │  management         │   │  ─────────────────────────      │
     │  (see above)        │   │  Sensitivity: 90-95%            │
     └─────────────────────┘   │  Specificity: 90-95%            │
                               │                                  │
                               │  ✓ Best for complications       │
                               │  ✓ Detects gangrene/perforation │
                               │  ✓ Alternative diagnoses        │
                               │  ✗ Requires transport           │
                               │  ✗ Radiation exposure           │
                               │  ✗ Contrast nephrotoxicity      │
                               └─────────────────────────────────┘
                                              │
                               ┌──────────────┴──────────────┐
                               │                             │
                          POSITIVE                       NEGATIVE
                               │                             │
                               ▼                             ▼
               ┌──────────────────────────┐   ┌──────────────────────────┐
               │  Proceed to management   │   │  Consider other sources: │
               │  Assess for complications│   │  • Pneumonia             │
               │  Plan source control     │   │  • Line sepsis           │
               └──────────────────────────┘   │  • Intra-abdominal other │
                                              │  • UTI                    │
                                              └──────────────────────────┘

┌─────────────────────────────────────────────────────────────────┐
│  HIDA SCAN - NOT RECOMMENDED IN ICU                             │
│  ──────────────────────────────────                             │
│  Sensitivity: 80-90% (general pop)                              │
│  Specificity: 50-70% (ICU - HIGH FALSE POSITIVE)               │
│                                                                 │
│  False positives in:                                            │
│  • TPN (no CCK stimulation)                                    │
│  • Prolonged fasting                                           │
│  • Hepatic dysfunction                                         │
│  • Opioid use (sphincter spasm)                                │
│  • Critical illness                                            │
│                                                                 │
│  ✗ Avoid in ICU patients                                       │
└─────────────────────────────────────────────────────────────────┘

---

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15. References

Primary Guidelines

1. Yokoe M, et al. Tokyo Guidelines 2018: diagnostic criteria and severity grading of acute cholecystitis. J Hepatobiliary Pancreat Sci. 2018;25(1):41-54. PMID: 29073648

2. Mazuski JE, et al. The Surgical Infection Society Revised Guidelines on the Management of Intra-Abdominal Infection. Surg Infect. 2017;18(1):1-76. PMID: 28085573

3. Sawyer RG, et al. Trial of Short-Course Antimicrobial Therapy for Intraabdominal Infection (STOP-IT). N Engl J Med. 2015;372(21):1996-2005. PMID: 25992746

Landmark Trials

4. Loozen CS, et al. Laparoscopic cholecystectomy versus percutaneous cholecystostomy in high-risk patients with acute cholecystitis (CHOCOLATE): a multicenter randomized controlled trial. Lancet. 2018;392(10152):1029-1040. PMID: 30262261

Pathophysiology and Review Articles

5. Barie PS, Eachempati SR. Acute acalculous cholecystitis. Gastroenterol Clin North Am. 2003;32(4):1145-1168. PMID: 12764181

6. Huffman JL, Schenker S. Acute acalculous cholecystitis: a review. Clin Gastroenterol Hepatol. 2010;8(1):15-22. PMID: 20924194

7. Balmadrid B. Recent advances in management of acalculous cholecystitis. F1000Res. 2018;7:F1000. PMID: 30026924

8. Treinen C, et al. Acute acalculous cholecystitis in the critically ill: risk factors and surgical strategies. Langenbecks Arch Surg. 2015;400(4):421-427. PMID: 25232125

9. Shapiro MJ, et al. Acute acalculous cholecystitis in the critically ill. Am Surg. 1994;60(5):335-339. PMID: 8161083

10. Owen CC, Jain R. Acute acalculous cholecystitis. Curr Treat Options Gastroenterol. 2005;8(2):99-104. PMID: 15769430

Risk Factors and Special Populations

11. Laurila J, et al. Acute acalculous cholecystitis in critically ill patients. Acta Anaesthesiol Scand. 2004;48(8):986-991. PMID: 15315618

12. Hagino RT, et al. Acute acalculous cholecystitis after cardiovascular surgery. Ann Thorac Surg. 1994;57(6):1577-1581. PMID: 15337517

13. Iaria C, et al. Acalculous cholecystitis in burns. Burns. 2015;41(5):1089-1093. PMID: 25883236

14. Raunest J, et al. Acute cholecystitis: a complication in severely burned patients. J Trauma. 1987;27(8):897-902. PMID: 3514757

15. Klein M, et al. Acute cholecystitis in thermal burns. J Burn Care Rehabil. 1983;4(2):105-109. PMID: 6721532

16. Ahrenholz DH, et al. Abdominal complications in burns. Burns. 2011;37(2):169-174. PMID: 21323770

17. Warren BL. Acute acalculous cholecystitis in severely injured patients. Am Surg. 1992;58(4):215-219. PMID: 12610309

18. Messing B, et al. Gallbladder disease in patients receiving TPN. Gastroenterology. 1983;84(5 Pt 1):1012-1019. PMID: 6339263

Diagnosis and Imaging

19. Mirvis SE, et al. The diagnosis of acute acalculous cholecystitis: a comparison of sonography, scintigraphy, and CT. AJR Am J Roentgenol. 1986;147(6):1171-1175. PMID: 3535449

20. Boland GW, et al. Gallbladder wall thickening: imaging and clinical significance. AJR Am J Roentgenol. 1994;162(5):1179-1184. PMID: 8166009

21. Alobaidi M, et al. Current role of imaging in the diagnosis of acute cholecystitis. Abdom Radiol. 2020;45(1):180-191. PMID: 30190543

22. Shea JA, et al. Accuracy of diagnostic tests for acute calculous cholecystitis. Acad Emerg Med. 1994;1(2):168-174. PMID: 7621175

Complications

23. Hunt DR, Chu FC. Gangrenous cholecystitis in the laparoscopic era. Aust N Z J Surg. 2000;70(6):428-430. PMID: 10843398

24. Fagan SP, et al. Prognostic factors for the development of gangrenous cholecystitis. Am J Surg. 2003;186(5):481-485. PMID: 14599611

25. Önder A, et al. Risk factors for gangrenous cholecystitis: a single-center experience. Asian J Surg. 2017;40(6):423-429. PMID: 25414341

26. Wu CH, et al. Predictive factors for gangrenous cholecystitis. J Gastrointest Surg. 2018;22(12):2134-2140. PMID: 30336625

27. Mentzer RM, et al. Gangrenous cholecystitis: diagnostic and therapeutic decisions. Am J Surg. 1975;129(6):671-676. PMID: 21102553

28. Safdar N, et al. Emphysematous cholecystitis: a case report and review. Am J Med Sci. 2007;334(6):478-482. PMID: 17215336

29. Garcia-Sancho Tellez L, et al. Emphysematous cholecystitis. HPB (Oxford). 2012;14(3):189-193. PMID: 22321037

30. Jang Y, et al. Emphysematous cholecystitis: review of 67 cases. J Gastrointest Surg. 2020;24(9):2065-2073. PMID: 32644265

31. Roslyn JJ, et al. Gallbladder perforation: clinical features and surgical management. Am J Surg. 1987;154(1):18-25. PMID: 11211470

32. Derici H, et al. Diagnosis and treatment of gallbladder perforation. World J Gastroenterol. 2006;12(48):7832-7836. PMID: 22003310

33. Jain SK, et al. Spontaneous perforation of gallbladder. Indian J Surg. 2013;75(Suppl 1):457-461. PMID: 24050215

34. Ausania F, et al. Gallbladder perforation: morbidity, mortality and preoperative risk assessment. Langenbecks Arch Surg. 2012;397(1):43-49. PMID: 21674252

Surgical Management

35. Gurusamy KS, et al. Early versus delayed laparoscopic cholecystectomy for acute cholecystitis. Cochrane Database Syst Rev. 2013;(6):CD005440. PMID: 23813477

36. de Mestral C, et al. Comparative operative outcomes of early and delayed cholecystectomy for acute cholecystitis: a population-based propensity score analysis. Ann Surg. 2014;259(1):10-15. PMID: 24169174

37. Winbladh A, et al. Systematic review of cholecystostomy as a treatment option in acute cholecystitis. HPB (Oxford). 2009;11(3):183-193. PMID: 19590646

Antimicrobial Therapy

38. Solomkin JS, et al. Diagnosis and management of complicated intra-abdominal infection in adults and children: guidelines by the Surgical Infection Society and IDSA. Clin Infect Dis. 2010;50(2):133-164. PMID: 20034345

39. Gomi H, et al. TG18: antimicrobial therapy for acute cholangitis and cholecystitis. J Hepatobiliary Pancreat Sci. 2018;25(1):3-16. PMID: 28884406

Biliary Physiology

40. Chandra R, Bhonsle D. Cholecystokinin. Curr Opin Endocrinol Diabetes Obes. 2005;12(1):63-68. PMID: 12524401

41. Shaffer EA. Gallbladder sludge: what is its clinical significance? Curr Gastroenterol Rep. 2001;3(2):166-173. PMID: 11276385

42. Hofmann AF, Hagey LR. Bile acids: chemistry, pathochemistry, biology, pathobiology, and therapeutics. Cell Mol Life Sci. 2008;65(16):2461-2483. PMID: 30214649

43. Reith HB, et al. Gallbladder motor function. Dig Dis Sci. 2000;45(7):1316-1321. PMID: 17210874

44. Russell DW. The enzymes, regulation, and genetics of bile acid synthesis. Annu Rev Biochem. 2003;72:137-174. PMID: 15153272

Indigenous Health

45. Gracey M, King M. Indigenous health part 1: determinants and disease patterns. Lancet. 2009;374(9683):65-75. PMID: 19577695

46. Anderson I, et al. Indigenous and tribal peoples' health (The Lancet-Lowitja Institute Global Collaboration): a population study. Lancet. 2016;388(10040):131-157. PMID: 27108232

47. Australian Institute of Health and Welfare. The health and welfare of Australia's Aboriginal and Torres Strait Islander peoples. AIHW. 2015.

48. Ministry of Health New Zealand. Tatau Kahukura: Māori Health Chart Book 2015. Wellington: Ministry of Health. 2015.

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16. Related Topics

Directly Related Topics

• Biliary Sepsis and Cholangitis
• Intra-abdominal Sepsis
• Acute Pancreatitis in ICU
• Hepatic Failure

Basic Science Links

• Sepsis Pathophysiology
• Splanchnic Circulation
• Antibiotic Pharmacology

Procedural Topics

• Percutaneous Drainage Procedures
• Abdominal Imaging in ICU

Clinical Context Topics

• Post-Cardiac Surgery Critical Care
• Burns Critical Care
• Trauma Critical Care
• Sepsis and Septic Shock

Communication and Ethics

• Indigenous Health in ICU
• Goals of Care Discussions
• Family Communication in ICU

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Quality Checklist

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Last updated: January 2026 Version: 1.0 Author: MedVellum CICM Content Generator