Anaesthesia for Laparoscopic Surgery

Quick Answer

Laparoscopic surgery presents unique physiological challenges: pneumoperitoneum (CO₂ insufflation 12-15 mmHg) increases intra-abdominal pressure causing cardiovascular effects (↓venous return initially, then ↑SVR and MAP; arrhythmias from CO₂/peritoneal stretch), respiratory effects (↓FRC, ↑peak airway pressures, cephalad diaphragm displacement, hypercapnia from CO₂ absorption), and renal effects (↓urine output from ↓renal perfusion and direct pressure). Anaesthetic management: General anaesthesia with muscle relaxation (pneumoperitoneum requires complete relaxation), controlled ventilation (increase minute ventilation 15-30% to compensate for CO₂ absorption), reverse Trendelenburg for upper abdominal (improves ventilation), Trendelenburg for lower abdominal/pelvic (improves surgical exposure). Positioning effects: Lithotomy (lower limb compartment syndrome risk), steep head-up (venous pooling), steep head-down (venous engorgement, atelectasis). Complications: CO₂ embolism (rare, fatal if massive), subcutaneous emphysema, pneumothorax/pneumomediastinum, arrhythmias, hypothermia (insufflation gas cold), conversion to open. [1-10]

Pathophysiology

Pneumoperitoneum Effects

Mechanism:

• CO₂ insufflation: 12-15 mmHg pressure (some centers use 10-12 mmHg, lower pressure safer)
• Purpose: Creates working space, improves visualization
• Absorption: CO₂ highly soluble, rapidly absorbed across peritoneum into circulation

Cardiovascular Effects:

Initial Phase (Insufflation - first 5-10 minutes):

• ↓Venous return: Increased intra-abdominal pressure compresses IVC and splanchnic veins
• ↓Cardiac output: May drop 10-30% initially
• ↓Blood pressure: Hypotension possible (especially in hypovolemic patients)
• Arrhythmias: Bradycardia (vagal response to peritoneal stretch), ectopy

Steady State (After 10-15 minutes):

• ↑Systemic vascular resistance (SVR): Mechanical compression, neurohumoral activation
• ↑Mean arterial pressure (MAP): Usually increases 10-20%
• ↑Central venous pressure: Reflects increased intra-abdominal pressure (not true volume status)
• ↑Cardiac filling pressures: PAOP and CVP artificially elevated
• ↑Myocardial workload: From increased afterload

Specific Concerns:

• Cardiac preload: Reduced venous return (↓preload)
• Afterload: Increased SVR (compensatory mechanism)
• Coronary perfusion: May be impaired (↑afterload + potential ↓aortic root pressure)
• Right heart strain: Pulmonary hypertension from ↓FRC, hypercapnia

Respiratory Effects:

Mechanical:

• ↑Intra-abdominal pressure: Pushes diaphragm cephalad
• ↓Functional residual capacity (FRC): 15-20% reduction
• ↓Total lung capacity: Restrictive physiology
• ↑Peak airway pressure: 30-50% increase (same tidal volume)
• ↓Compliance: Stiff chest wall and abdomen
• Atelectasis: Basal collapse common
• V/Q mismatch: Increased (wasted perfusion)

Gas Exchange:

• CO₂ absorption: 15-30 mL/min (can be >50 mL/min in some procedures)
• Hypercapnia: PaCO₂ increases 3-8 mmHg (varies with insufflation pressure, duration, patient)
• Respiratory acidosis: If ventilation not increased
• ↑Minute ventilation needed: 15-30% increase to maintain normocapnia

Positioning Interactions:

• Trendelenburg (head down): Worse respiratory compromise (further cephalad diaphragm)
• Reverse Trendelenburg (head up): Better respiratory mechanics (gravity assists)

Renal Effects:

• ↓Urine output: 30-50% reduction common
• Mechanisms:
  • Mechanical compression of renal veins and parenchyma
  • ↓Renal perfusion pressure (from ↑intra-abdominal pressure)
  • Activation of RAAS (renin-angiotensin-aldosterone system)
  • ADH release
• Temporary: Resolves with desufflation
• Oliguria common: Not necessarily hypovolemia

Hepatic/Splanchnic Effects:

• ↓Splanchnic perfusion: Portal venous compression
• ↓Hepatic blood flow: Arterial and venous
• Potential: Hepatic ischemia (rare clinically significant)
• Gut ischemia: Risk with prolonged pneumoperitoneum (>3-4 hours)

Cerebral Effects:

• ↑Intracranial pressure: From hypercapnia and ↓venous return (impaired cerebral venous drainage)
• Contraindication: Avoid head-down in patients with ↑ICP or space-occupying lesions

Positioning Effects

Trendelenburg (Head Down 15-30°):

• Used for: Lower abdominal/pelvic surgery (prostate, gynecology)
• Advantages: Bowel falls away from pelvis, improves exposure
• Disadvantages:
  • Cephalad shift of abdominal contents (worsens respiratory)
  • ↑CVP, ↑IOP, ↑ICP
  • Facial/upper airway edema (prolonged cases)
  • Shoulder pain from diaphragm stretch
  • Venous engorgement of head/neck

Reverse Trendelenburg (Head Up 15-30°):

• Used for: Upper abdominal surgery (gallbladder, stomach)
• Advantages:
  • Improves ventilation (gravity assists diaphragm)
  • Reduces ↑ICP/IOP
  • Bowel falls away from upper abdomen
• Disadvantages:
  • ↓Venous return (hypotension)
  • Venous pooling in legs
  • Risk of air embolism (if venous injury, though rare with CO₂)

Lithotomy:

• Position: Supine, legs flexed, abducted, supported in stirrups
• Risks:
  • Compartment syndrome (if legs improperly positioned or prolonged)
  • Common peroneal nerve injury (lateral knee pressure)
  • Hip dislocation (elderly)
  • ↓FRC (abdominal contents push up)
• Combined with: Trendelenburg (extreme position - legs up, head down)

Lateral Decubitus:

• Used for: Nephrectomy, adrenalectomy, splenectomy
• Considerations:
  • Ventilation-perfusion matching (dependent lung)
  • Pressure points (axilla, peroneal nerve)
  • Access for anaesthesia (often lateral position challenging)

CO₂ Embolism

Mechanism:

• CO₂ enters venous system (open vessel, trocar through vein)
• Travels to right heart, pulmonary circulation
• "Vapor lock" in pulmonary outflow tract

Presentation:

• Sudden: During insufflation or trocar insertion
• Hypotension: Severe, sudden
• ↓EtCO₂: Characteristic (dead space effect, CO₂ not reaching lungs)
• Hypoxemia: V/Q mismatch
• Arrhythmias: RV strain, ischemia
• Millwheel murmur: "Machinery" sound on precordial Doppler (rare)
• CVP elevation: Right heart failure

Severity:

• Small embolism: Transient hypotension, self-limited
• Massive embolism: Cardiovascular collapse, death
• Fatal dose: >5 mL/kg (large amount needed with CO₂ due to solubility)

Treatment:

1. Stop insufflation immediately
2. Release pneumoperitoneum (desufflate)
3. 100% O₂
4. Supportive: Vasopressors, fluids, CPR if arrest
5. Left lateral/Trendelenburg: Traps air in right ventricle (Débridement position)
6. Aspiration: From central line/right ventricle if catheter present
7. Prevention:
   • Verify trocar position before insufflation
   • Use low insufflation pressure initially
   • Monitor for sudden hypotension during insufflation

Note: CO₂ embolism less dangerous than air (N₂) because CO₂ highly soluble, rapidly absorbed. Air embolism more persistent.

Clinical Presentation

Preoperative Assessment

Cardiovascular:

• CAD: Assess severity (pneumoperitoneum increases myocardial O₂ demand)
• CHF: Higher risk (cannot tolerate ↓preload)
• Valvular disease: Severe AS particularly risky (fixed output cannot compensate)
• Arrhythmia history: Vagal reflex may trigger

Respiratory:

• COPD: Reduced reserve, harder to manage hypercapnia
• Obesity: Combined with pneumoperitoneum severely restricts ventilation
• OSA: Risk of airway obstruction postoperatively (especially after head-down)
• Restrictive disease: May not tolerate pneumoperitoneum

Other:

• Previous laparotomy: Adhesions, difficult dissection (higher conversion risk)
• Anticoagulation: Balance thrombosis vs bleeding risk
• Pregnancy: Second trimester safest if necessary (uterus size)

Contraindications (Relative)

• Severe cardiopulmonary disease: May not tolerate pneumoperitoneum
• ↑ICP (space-occupying lesion): Head-down contraindicated
• Uncorrected hypovolemia: Severe hypotension with insufflation
• Generalized peritonitis: Open procedure preferred
• Massive hemoperitoneum: Open for control
• Large abdominal mass: Limited working space

Management

Anaesthetic Technique

General Principles:

• GA required: Pneumoperitoneum intolerable under regional alone
• Muscle relaxation: Essential (complete relaxation needed for pneumoperitoneum)
• Controlled ventilation: Mandatory (hypercapnia management)
• Access: Large-bore IV, arterial line if indicated

Monitoring:

• Standard: ECG, SpO₂, NIBP, EtCO₂, temperature
• Arterial line:
  • Long cases (>2 hours)
  • Cardiac comorbidity
  • Frequent ABGs needed (verify PaCO₂)
• CVP: Consider if cardiac disease (interpret cautiously - artificially elevated)
• TOF: Neuromuscular monitoring (ensure adequate block)
• BIS: Optional (depth monitoring)
• Urinary catheter: Long procedures (monitor urine output)

Induction:

• Standard: Propofol/fentanyl/rocuronium
• RSI if: Full stomach (emergency laparoscopy), obesity, hiatal hernia
• Position: Supine initially (after intubation, position for surgery)

Maintenance:

• TIVA or balanced: Either acceptable
• Muscle relaxation: Continuous (infusion or intermittent boluses)
  • Check TOF (aim 1-2 twitches)
  • Rocuronium, vecuronium, atracurium all suitable
• Analgesia: Multimodal
  • Opioids: Fentanyl, remifentanil
  • NSAIDs: If no contraindication (ketorolab, parecoxib)
  • Local: Port sites infiltration
  • TAP block: Postoperative analgesia (especially lower abdominal)

Ventilation Strategy:

• Mode: Volume control or pressure control
• Target: Normocapnia (PaCO₂ 35-40 mmHg)
• Adjustments:
  • Increase minute ventilation 15-30% above baseline
  • May need respiratory rate 14-18, tidal volume 8-10 mL/kg
  • Monitor EtCO₂ and trend (increases with duration of pneumoperitoneum)
  • Peak pressures: Accept up to 30-35 cm H₂O (will be higher)
  • PEEP: 5 cm H₂O (helps counteract atelectasis)
• ABG: Check if long case or cardiac/respiratory disease

Insufflation Management:

• Start low: 10-12 mmHg (lower = less physiological disturbance)
• Maximum: 15 mmHg (higher pressures increase complications)
• Monitor: Sudden hypotension, arrhythmias (CO₂ embolism)
• Flow: Start low (1-3 L/min), increase gradually
• Total CO₂ used: Monitor (excessive = leak/subcutaneous emphysema)

Hemodynamic Management:

• Pre-insufflation: Ensure euvolemia (fluids if dry)
• During insufflation:
  • Expect ↑MAP 10-20% (acceptable)
  • If hypotension: Desufflate partially, give fluids, check for hemorrhage
  • If severe hypertension: Deepen anaesthesia, consider vasodilators
• Bradycardia: Atropine 0.5-1 mg (vagal reflex)
• Positioning: Adjust slowly, watch for hypotension (Trendelenburg improves BP, Reverse reduces)

Fluid Management:

• Standard crystalloid: Hartmann's or Plasma-Lyte
• Volume:
  • Maintenance: 4-2-1 rule
  • Deficit replacement if prolonged NPO
  • Third space: Moderate 2-4 mL/kg/hour
• Caution: Avoid fluid overload (especially in cardiac/renal patients)
• Oliguria common: From pneumoperitoneum, not necessarily hypovolemia

Temperature:

• Cold CO₂: Insufflation gas at room temperature (cooling)
• Active warming: Forced air warmer essential (large surface area exposed)
• Humidification: Helps reduce heat loss
• Target: Normothermia (>36°C)

Specific Procedures

Laparoscopic Cholecystectomy:

• Position: Reverse Trendelenburg 15-30° + left tilt (expose gallbladder)
• Duration: 30-60 minutes typically
• Analgesia: TAP block effective, port site infiltration
• Risk: CBD injury (conversion if major bleeding)

Laparoscopic Appendectomy:

• Position: Trendelenburg + left tilt (expose appendix)
• Simpler: Lower insufflation pressures often possible
• Postoperative pain: Lower than open

Laparoscopic Hernia Repair (TAPP/TEP):

• Position: Trendelenburg
• Bilateral: Longer procedure
• Specific: Extraperitoneal (TEP) avoids peritoneal cavity (less physiological effects)

Laparoscopic Colectomy:

• Duration: Long (2-4 hours)
• Position: Variable (Trendelenburg, lateral, supine)
• Consider: Arterial line, frequent ABGs
• Risk: Conversion higher (difficult dissection)

Laparoscopic Gynecology:

• Position: Trendelenburg + lithotomy
• Combined effects: Respiratory compromise most pronounced
• Specific: Risk of brachial plexus injury (shoulder braces if steep Trendelenburg)

Bariatric Surgery:

• Specific chapter: See "bariatric-surgery.mdx"
• Key points:
  • Extreme positioning challenges
  • High airway pressures (BMI + pneumoperitoneum)
  • Increased risk of desaturation
  • DVT prophylaxis crucial

Conversion to Open

Indications:

• Uncontrolled bleeding: Cannot achieve hemostasis laparoscopically
• Severe physiological disturbance: Cannot tolerate pneumoperitoneum
• Complication: Major vessel injury, bowel injury requiring open repair
• Technical: Inability to complete procedure safely
• Equipment failure: Loss of visualization

Anaesthetic Management:

• Communication: Early warning from surgeon ("may need to open")
• Preparation: Blood products, warming, large-bore IV
• Rapid conversion: Sudden physiological improvement with desufflation
• Continue GA: Maintain anaesthesia for open procedure
• Postoperative: ICU if major blood loss or instability

Postoperative Management

Emergence:

• Desufflate completely: Before closure (reduces residual CO₂)
• Reverse paralysis: Ensure TOF ratio >0.9
• Extubate awake: Following commands (especially obese, OSA)
• Position: Supine before extubation

Pain Management:

• Multimodal:
  • Paracetamol 1 g IV q6h
  • NSAIDs: Ketorolab, parecoxib, ibuprofen (if no contraindication)
  • Opioids: Morphine PCA or oxycodone PRN
  • Local: TAP block, wound infiltration
• Shoulder pain: Common (diaphragm irritation from CO₂)
  • Treat with NSAIDs, opioids
  • Resolves 24-48 hours
• Non-opioid priority: Reduce ileus, nausea

Nausea/Vomiting:

• High risk: Laparoscopy has high PONV incidence
• Prophylaxis:
  • Dexamethasone 4-8 mg
  • Ondansetron 4 mg
  • TIVA (propofol reduces PONV)
  • Adequate hydration
  • Avoid N₂O (controversial, may increase PONV)

Respiratory:

• Atelectasis: Common postoperatively
• Hypoxemia: Especially obese, elderly, prolonged surgery
• Management: O₂, incentive spirometry, early mobilization

Complications to Monitor:

1. Surgical complications:
   • Bleeding (retroperitoneal, port sites)
   • Bowel injury
   • Bile leak (cholecystectomy)
   • Anastomotic leak (colectomy)
2. Respiratory:
   • Pneumothorax (subcutaneous emphysema extending to chest)
   • Atelectasis, pneumonia
3. Thromboembolism: DVT/PE (Trendelenburg + lithotomy + insufflation = stasis)
4. Compartment syndrome: Lower limb (lithotomy position)
5. Nerve injuries: Brachial plexus, common peroneal

Day Surgery:

• Common: Laparoscopic cholecystectomy, appendectomy, diagnostic
• Criteria for discharge:
  • Pain controlled with oral analgesia
  • Tolerating oral intake
  • Ambulating without dizziness
  • No respiratory distress
  • Urinating (may take longer after pelvic surgery)

Indigenous Health Considerations

Aboriginal and Torres Strait Islander Patients

Higher Prevalence:

• Gallstones: Higher rates in some Indigenous populations (diet, genetics)
• Obesity: Higher rates (bariatric surgery need)
• Diabetes: Complicates perioperative care

Access Issues:

• Regional/rural: Laparoscopic surgery may not be available locally
• Travel: Need for travel to regional centers
• Family separation: Extended stay away from community

Postoperative Care:

• Communication: Clear instructions for pain management, activity
• Follow-up: Ensure access to care if complications
• Cultural support: During hospital stay

Māori Health Considerations

Health Disparities:

• Higher obesity rates (bariatric surgery candidates)
• Higher gallstone disease in some regions

Cultural Safety:

• Whānau involvement: Family support for surgical admission
• Communication: Clear preoperative and postoperative instructions
• Discharge planning: Ensure understanding of recovery at home

ANZCA Final Exam Focus

SAQ Patterns

Common Questions:

• "Describe the physiological effects of pneumoperitoneum."
• "How would you manage ventilation during laparoscopic surgery?"
• "What are the complications of laparoscopic surgery and how do you manage them?"
• "Compare the physiological effects of Trendelenburg vs reverse Trendelenburg position."

Marking Scheme Priorities:

• Cardiovascular effects (↑SVR, ↑MAP, ↓venous return initially, arrhythmias)
• Respiratory effects (↓FRC, ↑airway pressures, hypercapnia from CO₂ absorption)
• Ventilation management (increase minute ventilation 15-30%, monitor EtCO₂)
• CO₂ embolism (recognition: ↓EtCO₂, hypotension; management: stop insufflation, supportive)
• Positioning effects (Trendelenburg vs reverse, lithotomy risks)

Viva Scenarios

Scenario 1: Severe Hypercapnia

• PaCO₂ 65 mmHg, EtCO₂ 55 mmHg during laparoscopic cholecystectomy
• Management: Increase minute ventilation (rate and/or tidal volume), check for subcutaneous emphysema, consider desufflation if severe

Scenario 2: Sudden Hypotension During Insufflation

• BP drops to 60/40, HR 45 immediately after starting CO₂ insufflation
• Differential: CO₂ embolism (less likely immediately), severe vagal response, hypovolemia, cardiac event
• Management: Stop insufflation, atropine for bradycardia, fluids, support, check trocar position

Scenario 3: Subcutaneous Emphysema

• Extensive crepitus in chest/neck during prolonged case
• Risk: Pneumothorax, hypercapnia (CO₂ in tissues)
• Management: Reduce insufflation pressure, check for pneumothorax (CXR), increase ventilation, may need to convert

Key Points for Examination Success

1. Pneumoperitoneum pressure: 12-15 mmHg (lower safer)
2. Cardiovascular: Initial ↓CO possible, steady state ↑SVR and ↑MAP
3. Respiratory: ↓FRC, ↑peak pressures (30-50%), need to increase minute ventilation 15-30%
4. CO₂ absorption: 15-30 mL/min, causes hypercapnia
5. Positioning: Trendelenburg (pelvic surgery, ↓respiratory), reverse Trendelenburg (upper abdominal, better respiratory)
6. CO₂ embolism: ↓EtCO₂ (diagnostic), hypotension, stop insufflation, supportive care
7. Renal: ↓Urine output from pressure (not hypovolemia necessarily)
8. Contraindications: Severe cardiorespiratory disease, ↑ICP (head-down), uncorrected hypovolemia
9. Analgesia: Multimodal, TAP block, NSAIDs, avoid opioids if possible
10. PONV: High risk - prophylactic antiemetics essential

References

1. ANZCA. PS45. Guidelines for Transport and Positioning of Patients. 2018.
2. Joris JL. Anesthesia for laparoscopic surgery. In: Miller RD (ed). Miller's Anesthesia. 9th ed. Elsevier; 2020:2110-2128.
3. O'Malley C et al. Physiologic changes during laparoscopy. Anesthesiol Clin North Am. 2001;19(1):1-19.
4. Falabella A et al. Cardiac arrest during laparoscopic surgery. JSLs. 2007;11(4):468-472.
5. Gutt CN et al. Circulatory and respiratory complications of CO₂ pneumoperitoneum. Surg Endosc. 2004;18(12):1713-1723.
6. Motew M et al. Cardiovascular effects of CO₂ insufflation. Anesthesiology. 1973;39(5):560-565.
7. Sharma KC et al. Cardiopulmonary physiology and pathophysiology as a consequence of laparoscopic surgery. Chest. 1996;110(3):810-815.
8. ATSI Health. Obesity and related conditions in Aboriginal and Torres Strait Islander peoples. Australian Institute of Health and Welfare; 2020.