Anaesthesia for Endoscopic Sinus Surgery (FESS)

Quick Answer

Functional Endoscopic Sinus Surgery (FESS) is a minimally invasive technique for treating chronic rhinosinusitis, nasal polyps, and skull base pathology. Key anaesthetic challenges include:

• Controlled Hypotension: Essential for surgical field visualisation. Target MAP 60-65 mmHg (or 20% below baseline) reduces bleeding and improves visibility in highly vascular sinonasal mucosa [1,2]

• Bleeding Management: Despite controlled hypotension, bleeding can be significant (200-500 mL in complex cases). Reverse Trendelenburg position, topical vasoconstriction (oxymetazoline/cocaine), head-up tilt all reduce bleeding [3,4]

• Skull Base Risks: Thin cribriform plate and fovea ethmoidalis separate sinuses from anterior cranial fossa. Risk of:

  • CSF leak (0.5-2%)
  • Orbital penetration (0.1-1%) with potential visual loss
  • Intracranial haemorrhage (rare, catastrophic)
  • Carotid artery injury (extremely rare, fatal) [5,6,7]

• Airway Considerations: Shared airway with surgeon; oral RAE tube positioned at midline or contralateral side; risk of tube compression with head manipulation; throat pack commonly used [8,9]

• Patient Positioning: Reverse Trendelenburg 15-30° reduces venous bleeding; may use head-up sitting position for some approaches; ensure venous return from head [10,11]

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Indigenous Health Considerations

Aboriginal and Torres Strait Islander Populations

Chronic Rhinosinusitis (CRS) and Nasal Polyps represent significant health burdens in Aboriginal and Torres Strait Islander populations, though less extensively studied than otitis media. Available evidence demonstrates:

• Higher prevalence of CRS: Contributing factors include overcrowded housing with poor ventilation, exposure to biomass fuel smoke, and higher rates of atopy and allergic sensitisation [12,13]
• Comorbid allergic rhinitis: Higher rates in Indigenous populations, particularly in remote communities with exposure to specific environmental allergens
• Asthma co-existence: Strong link between upper and lower airway disease; asthma rates elevated in Indigenous populations (10-15% vs 8-10% non-Indigenous) [14,15]

Barriers to FESS access:

1. Geographic isolation: ENT specialist services concentrated in major cities; remote patients require travel to metropolitan centres
2. Delayed diagnosis: Limited access to CT imaging and diagnostic endoscopy in rural/remote areas
3. Cultural factors: Some Indigenous patients may prefer traditional healing approaches for chronic conditions before considering surgery
4. Cost and logistics: Travel, accommodation, time away from family and country create significant barriers
5. Follow-up challenges: Postoperative endoscopic debridement and monitoring difficult for remote patients; recurrence risk higher [16,17,18]

Perioperative considerations:

• Smoking rates: Higher tobacco smoking rates (40-50% vs 12-15% non-Indigenous) increase perioperative respiratory complications and impair wound healing
• Nutritional status: Food insecurity in remote communities may affect healing; preoperative optimisation important
• Communication: Need for interpreter services or Aboriginal Health Workers; visual aids helpful for explaining complex sinus anatomy
• Skin necrosis risk: Some skin grafts (for skull base reconstruction) may have higher failure rates in the context of comorbidities [19,20,21]

Cultural safety:

• "Men's Business" considerations: Some nasal/sinus procedures may involve sensitive discussions for male patients; male health workers or family members may be preferred
• Country and family: Extended absence from community for surgery may cause distress; telehealth follow-up reduces travel burden
• Traditional medicine interactions: Some traditional preparations may affect coagulation or interact with anaesthetics; respectful medication reconciliation needed [22,23,24]

Māori Populations (Aotearoa New Zealand)

Chronic rhinosinusitis burden:

• Māori demonstrate similar patterns of chronic rhinosinusitis with nasal polyps compared to European New Zealanders
• Higher asthma prevalence (16% vs 9% non-Māori) increases the unified airway disease burden requiring comprehensive management [25,26]
• Aspirin-exacerbated respiratory disease (AERD): Samter's triad (asthma, nasal polyps, aspirin sensitivity) may be underdiagnosed in Māori populations [27,28]

Equity considerations:

• Rheumatic fever connection: Chronic nasal carriage of Streptococcus pyogenes may contribute to rheumatic fever risk; some Māori with severe CRS may be expedited for surgery to reduce this risk
• Tobacco exposure: Second-hand smoke exposure in crowded housing contributes to both upper and lower airway disease
• Dust mite exposure: Lower rates of house dust mite sensitisation in Māori compared to Europeans, but higher rates of mould and pollen sensitisation [29,30]

Te Tiriti o Waitangi obligations:

1. Whānau-centred care: Family involvement in surgical decision-making and postoperative care planning
2. Māori Health Workers: Navigation support for complex tertiary-level care
3. Data contribution: Ensuring Māori-specific outcomes data contributes to workforce development and service planning
4. Rural equity: Partnership with rural iwi for follow-up care using telehealth and local services
5. Cultural safety: Recognition that chronic respiratory disease disproportionately affects Māori whānau and communities [31,32,33]

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Epidemiology and Clinical Overview

Indications for FESS

Chronic rhinosinusitis (CRS):

• CRS with nasal polyps (CRSwNP)
• CRS without nasal polyps (CRSsNP)
• Failed maximal medical therapy (typically 3 months)
• Significant quality of life impact

Complicated acute rhinosinusitis:

• Orbital cellulitis/abscess
• Intracranial complications (meningitis, abscess, cavernous sinus thrombosis)
• Osteomyelitis of frontal bone (Pott's puffy tumour)

Neoplastic and skull base:

• Benign sinonasal tumours (inverted papilloma, angiofibroma)
• Malignant sinonasal tumours (squamous cell carcinoma, esthesioneuroblastoma)
• Anterior skull base tumours (meningioma)
• Cerebrospinal fluid leaks (traumatic or spontaneous)
• Encephalocele repair
• Pituitary surgery (transsphenoidal approach)

Other:

• Fungal sinusitis (allergic fungal, mycetoma, invasive)
• Mucocele drainage
• Foreign body removal
• Choanal atresia repair [34,35,36]

Surgical Techniques

Operative duration:

• Simple FESS (uncinectomy, antrostomy): 30-60 minutes
• Standard FESS (anterior/posterior ethmoidectomy): 1-2 hours
• Complex/skull base: 3-6 hours or longer [39,40]

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Anatomy and Physiology Relevant to Anaesthesia

Sinonasal Anatomy

The paranasal sinuses are air-filled cavities within the skull:

• Maxillary sinuses: Largest; located lateral to nasal cavity; drain via ostium in middle meatus
• Ethmoid sinuses: Multiple small air cells between medial orbit and nasal cavity; divided into anterior and posterior groups by basal lamella
• Frontal sinuses: Superior to nasal cavity; variable pneumatization; drain via frontal recess
• Sphenoid sinuses: Posterior to ethmoids; close relationship to optic nerve, internal carotid artery, cavernous sinus [41,42,43]

Critical skull base relationships:

• Cribriform plate: Thin bone (0.5-2 mm) separating olfactory fossa from anterior cranial fossa; site of CSF leak risk
• Fovea ethmoidalis: Roof of ethmoid sinuses; lateral to cribriform plate; thin bone separating sinuses from frontal lobes
• Lamina papyracea: Paper-thin bone separating ethmoid sinuses from orbit; site of orbital penetration risk
• Onodi cell: Posterior ethmoid cell lateral and superior to sphenoid sinus; may contain optic nerve or internal carotid artery [44,45,46]

Arterial supply and bleeding risk:

• Internal carotid artery: Courses through sphenoid sinus in 20-30% of patients; catastrophic if injured
• Anterior and posterior ethmoidal arteries: Branch from ophthalmic artery; major bleeding sources in ethmoidectomy
• Sphenopalatine artery: Terminal branch of maxillary artery; supplies posterior nasal cavity and sinuses; controlled with cautery
• Kiesselbach's plexus: Anterior nasal septum; bleeding common but easily controlled [47,48,49]

Physiology of Controlled Hypotension

Rationale: The sinonasal mucosa is highly vascular. Reducing mean arterial pressure (MAP) to 60-65 mmHg or 20% below baseline reduces arterial inflow and capillary pressure, significantly improving surgical visibility by reducing bleeding and oozing [50,51].

Physiological considerations:

• Cerebral autoregulation: Maintains constant cerebral blood flow between MAP 60-150 mmHg in normotensive patients
• Coronary autoregulation: Generally maintained above MAP 50-60 mmHg in healthy patients
• Renal perfusion: Generally preserved down to MAP 60 mmHg due to autoregulation
• Cautions: Elderly, hypertensive patients, coronary artery disease, cerebrovascular disease - higher MAP targets needed (70-80 mmHg) [52,53,54]

Techniques for controlled hypotension:

• Increased depth of anaesthesia: Higher volatile concentration or propofol infusion
• Beta-blockade: Labetalol, esmolol (reduce myocardial oxygen demand)
• Calcium channel blockers: Nicardipine (vasodilation)
• Nitroglycerin: Venodilation reduces preload
• Remifentanil: Sympathetic suppression; dose-dependent hypotension
• Dexmedetomidine: Reduces sympathetic tone and anaesthetic requirements [55,56,57,58]

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Preoperative Assessment

History and Examination

ENT-specific:

• Duration and severity of rhinosinusitis symptoms
• Previous sinus surgeries and complications
• Nasal polyps: unilateral vs bilateral, recurrence history
• Comorbid asthma and allergic rhinitis
• Anosmia (loss of smell) - important quality of life marker
• Orbital symptoms (diplopia, proptosis, visual changes) - red flag
• Neurological symptoms (headache, meningismus) - red flag
• History of epistaxis and bleeding disorders [59,60,61]

Systemic assessment:

• Cardiovascular: Hypertension (controlled hypotension concerns); ischaemic heart disease (hypotension risk); anticoagulant/antiplatelet use
• Respiratory: Asthma control; recent exacerbations; medication compliance
• Haematological: Coagulation disorders; hereditary haemorrhagic telangiectasia (HHT)
• Neurological: Previous cerebrovascular disease; increased intracranial pressure concerns [62,63,64]

Medications:

• Aspirin/NSAIDs: Usually stopped 7-10 days preoperatively to reduce bleeding (though controversial for cardiac patients)
• Clopidogrel: Stop 5-7 days preoperatively if possible
• Warfarin: Stop 5 days preoperatively; bridge with heparin if high-risk
• DOACs: Stop per standard protocols (generally 24-48 hours for standard bleeding risk)
• Intranasal steroids: Continue preoperatively; may reduce bleeding [65,66,67]

Investigations

Routine:

• CT paranasal sinuses (essential for surgical planning; identifies anatomical variants, extent of disease, skull base thickness)
• FBC (baseline; cross-match 2 units for complex/skull base cases)
• Coagulation studies if anticoagulants or bleeding history

Selected patients:

• MRI (soft tissue tumours, intracranial extension, optic nerve involvement)
• Allergic testing (allergic fungal sinusitis, aspirin desensitization candidates)
• ECG if cardiovascular disease or age >60
• CXR if respiratory symptoms
• Cystic fibrosis screening (in children with nasal polyps) [68,69,70]

Risk Stratification

High-risk for skull base complications:

• Revision surgery (scar tissue obscures anatomy)
• Extensive polyposis (distorted landmarks)
• Low-lying skull base (<5 mm from keros reference)
• Asymmetry in ethmoid roof height
• Previous skull base injury [71,72,73]

Contraindications to controlled hypotension:

• Severe aortic stenosis
• Recent myocardial infarction (<6 months)
• Cerebrovascular disease with flow-limiting stenosis
• Severe untreated hypertension (preoperative optimisation needed)
• Severe carotid stenosis
• Acute blood loss anaemia [74,75,76]

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Intraoperative Management

Anaesthetic Technique

Induction:

• Standard IV induction (propofol 2-3 mg/kg, fentanyl 1-2 mcg/kg)
• Ensure adequate depth before instrumentation to prevent laryngospasm
• Dexamethasone 8-10 mg IV at induction (reduces tissue oedema, improves surgical field, provides antiemesis) [77,78]

Airway management:

• Oral RAE endotracheal tube: Positions circuit away from surgical field
• Positioning: Tube secured at midline (if surgeon operates from both sides) or contralateral side
• Nasal intubation: Generally avoided in nasal surgery; may be used for skull base cases with oral cavity involvement
• Throat pack: Placed by surgeon to prevent blood entering airway; must be removed at end [79,80]

Maintenance:

• TIVA (propofol 100-150 mcg/kg/min + remifentanil 0.05-0.2 mcg/kg/min) increasingly preferred:
  • Excellent for controlled hypotension (remifentanil provides dose-dependent BP control)
  • No interference with facial nerve monitoring if needed
  • Reduces PONV
  • Smooth emergence
• Volatile agents: Isoflurane, sevoflurane acceptable; depth titrated for hypotension
• Nitrous oxide: Generally avoided (may expand sinuses, increases PONV, supports combustion if cautery accident) [81,82,83]

Controlled Hypotension Protocol

Target parameters:

• MAP: 60-65 mmHg in healthy patients
• Higher targets: 70-80 mmHg in elderly, hypertensive patients, or those with cardiovascular/cerebrovascular disease
• Systolic BP: Generally 80-90 mmHg (higher if indicated)
• Duration: Throughout dissection phases; may allow gradual return toward baseline during reconstruction/emergence [84,85,86]

Stepwise approach:

1. Positioning: Reverse Trendelenburg 15-30°; head-up tilt
2. Anaesthetic depth: Increase propofol or volatile concentration to sympathetic-suppressing levels
3. Remifentanil: Titrate 0.1-0.3 mcg/kg/min to achieve target MAP
4. Adjunctive agents if needed:
   • Labetalol 5-10 mg IV bolus (beta-blockade with some alpha effect)
   • Esmolol 0.5-1 mg/kg IV then 50-300 mcg/kg/min infusion (titrable, short-acting)
   • Nicardipine 0.5-1 mg IV then 1-5 mg/hr infusion (calcium channel blocker)
   • Nitroglycerin 0.5-2 mcg/kg/min (venodilation) [87,88,89]

Monitoring during controlled hypotension:

• Arterial line: Mandatory for precise, continuous BP monitoring; frequent blood gas sampling if prolonged procedure
• Depth of anaesthesia: BIS or entropy monitoring helpful to ensure adequate depth
• Neurological: No specific monitoring unless intracranial surgery; cerebral oximetry may be used in high-risk patients
• End-organ perfusion: Urine output >0.5 mL/kg/hr; lactate levels if prolonged hypotension [90,91,92]

Reversal of hypotension:

• Gradual reduction of remifentanil/propofol infusion rates
• Lightening anaesthetic depth
• Head-down positioning if urgent reversal needed
• Phenylephrine or ephedrine boluses for acute hypertension on emergence [93,94]

Positioning

Reverse Trendelenburg:

• 15-30° head-up tilt: Reduces venous engorgement of sinonasal mucosa
• Improves venous drainage from head and neck
• Reduces bleeding and improves surgical field
• Caution: May reduce venous return and cardiac output; ensure adequate volume status

Head positioning:

• Slight extension for most FESS
• May require rotation for specific approaches
• Ensure no pressure on eyes (risk of orbital injury from positioning + surgical risk)
• Neck in neutral position to avoid venous obstruction

Pressure area care:

• Occiput at risk (head elevated)
• Heels, sacrum, elbows require padding
• Arms tucked or positioned carefully to avoid brachial plexus stretch
• Eye protection (taping lids closed, padding) [95,96,97]

Surgical Stages and Anaesthetic Considerations

Bleeding Management Strategies

Preoperative optimisation:

• Stop anticoagulants/antiplatelets per protocol
• Continue intranasal corticosteroids
• Optimise blood pressure control

Intraoperative techniques:

• Topical vasoconstriction:
  • Oxymetazoline 0.05% (Afrin) spray - long-acting, effective
  • Cocaine 4-10% solution - excellent vasoconstriction plus anaesthesia; total dose <1.5 mg/kg (toxicity risk)
  • Adrenaline 1:1000 on pledgets - potent but systemic absorption [101,102]
• Controlled hypotension: As described above
• Positioning: Reverse Trendelenburg, head-up
• Ventilation: Moderate hypocapnia (PaCO₂ 30-35 mmHg) causes cerebral vasoconstriction; may reduce bleeding slightly (controversial) [103,104]
• Tranexamic acid: 1 g IV at induction may reduce bleeding (limited evidence specific to FESS but general benefit in mucosal surgery) [105,106]

Major bleeding response:

• Communicate with surgeon immediately
• Gradual reduction of controlled hypotension (not sudden - may worsen view)
• Fluid resuscitation if significant blood loss
• Blood products if needed
• Surgical control with cautery or packing
• Consider conversion to external approach if endoscopic control impossible [107,108]

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Complications and Management

Intraoperative Complications

Cerebrospinal fluid leak:

• Recognition: Surgeon visualises clear fluid egress, "waterfall" sign, or brain tissue
• Incidence: 0.5-2% for standard FESS; higher in skull base surgery
• Risk factors: Revision surgery, extensive polyposis, low skull base, surgeon inexperience
• Management:
  • Inform surgeon immediately
  • Maintain controlled hypotension (reduce bleeding into cranium)
  • Request neurosurgical assistance if large defect
  • Surgical repair with graft (fascia, fat, mucosa)
  • Postoperative: head-up positioning, avoid straining, stool softeners, consider lumbar drain
  • Antibiotics to prevent meningitis [109,110,111]

Orbital penetration:

• Recognition: Orbital fat herniation into surgical field, orbital bleeding, diplopia on wake-up, "teardrop" pupil
• Incidence: 0.1-1% depending on complexity
• Consequences: Orbital haematoma → increased intraocular pressure → optic nerve ischaemia → permanent visual loss if >90 minutes
• Management:
  • Immediate recognition and surgeon notification
  • Ophthalmology emergency consultation
  • Lateral canthotomy and inferior cantholysis if orbital compartment syndrome
  • Mannitol 1 g/kg IV to reduce intraocular pressure
  • High-dose steroids (controversial but commonly used)
  • Orbital decompression if needed [112,113,114]

Major arterial bleeding:

• Ethmoidal arteries: Can retract into orbit causing orbital haematoma; may require external approach for control
• Sphenopalatine artery: Usually controlled with endoscopic cautery
• Internal carotid artery: Catastrophic; immediate packing, resuscitation, interventional radiology; high mortality even with optimal care
• Management: Rapid communication, controlled hypotension, blood products, surgical control or interventional radiology embolization [115,116,117]

Tension pneumocephalus:

• Mechanism: Nitrous oxide use with CSF leak → gas enters intracranial space; N₂O discontinuation → contraction of gas space creates negative pressure → venous bleeding into intracranial space
• Prevention: Avoid N₂O if skull base surgery or CSF leak risk
• Recognition: Delayed emergence, pupillary changes, neurological deficit
• Management: Urgent CT imaging; neurosurgical consultation; may require burr hole for decompression [118,119,120]

Postoperative Management

Emergence strategy:

• Critical requirement: Smooth emergence without coughing or sneezing (increases venous pressure and bleeding)
• Techniques:
  • Deep extubation in selected patients (airway must be manageable)
  • IV lidocaine 1-1.5 mg/kg 3-5 minutes before emergence
  • Dexmedetomidine or remifentanil infusion until extubation
  • Nasal decongestant spray before extubation to reduce sneezing
• Position: Head-up 30° immediately post-extubation [121,122,123]

Nasal packing:

• Materials: Merocel, Rapid Rhino, bismuth-iodine-paraffin paste (BIPP), gauze
• Duration: Usually 24-48 hours; may be longer in skull base surgery or if bleeding concern
• Anaesthetic implications: Nasal obstruction requires mouth breathing; humidified oxygen helpful; analgesia important (packing removal painful) [124,125]

Pain management:

• Multimodal approach:
  • Paracetamol 1 g IV/PO q6h
  • NSAIDs (ibuprofen 400 mg q8h or diclofenac 50 mg q8h) unless contraindicated by bleeding
  • Weak opioids (tramadol 50-100 mg PRN) if needed
  • Topical anaesthetic spray for packing discomfort
• Avoid: Aspirin and strong opioids if possible (increase bleeding risk and PONV) [126,127]

Postoperative monitoring:

• Visual assessment: Document visual acuity and fields postoperatively; any changes require urgent ophthalmology review
• Neurological: Level of consciousness, headache assessment (differentiate from normal post-FESS headache vs. intracranial complication)
• Bleeding: Persistent epistaxis; posterior bleeding may manifest as haemoptysis or haematemesis from swallowed blood
• CSF leak: Clear watery rhinorrhoea, salty taste, "halo sign" on gauze (clear fluid ring around blood)
• Positioning: Head-up 30-45° for 24-48 hours reduces bleeding and oedema [128,129,130]

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Special Populations and Situations

Revision FESS

• Higher complication risk: Scar tissue obscures normal anatomy; skull base and orbital structures harder to identify
• Higher bleeding risk: Scar tissue is vascular; landmarks distorted
• Anaesthetic modifications:
  • More aggressive controlled hypotension (if safe)
  • Arterial line mandatory
  • Higher transfusion threshold (cross-match 2-4 units)
  • Longer operative time anticipated
  • Consider booking extended recovery or observation [131,132]

Skull Base Surgery (Endoscopic Endonasal Approach)

• Extended duration: 4-8 hours common
• Multidisciplinary: ENT surgeon + neurosurgeon
• Neurosurgical anaesthesia considerations:
  • Mannitol 0.25-0.5 g/kg IV for brain relaxation
  • Moderate hypocapnia (PaCO₂ 30-35 mmHg) for cerebral vasoconstriction
  • Strict fluid management (avoid hyponatraemia)
  • Urinary catheter mandatory
  • Temperature management (prevent hypothermia)
• Lumbar drain: Sometimes placed preoperatively for CSF drainage to improve surgical access [133,134,135]

Pituitary Surgery (Transsphenoidal)

• Endocrinological considerations:
  • Hypopituitarism: May require perioperative hydrocortisone stress-dose steroids
  • Cushing's disease: Difficult airway, hypertension, diabetes, poor wound healing
  • Acromegaly: Difficult airway, cardiomyopathy, hypertension
• Cerebrospinal fluid leak: Higher risk (sella turcica entered)
• Diabetes insipidus: May develop postoperatively; monitor urine output and electrolytes [136,137,138]

Anticoagulated Patients

• Warfarin: Stop 5 days preoperatively; INR <1.5 for surgery; bridge with LMWH or UFH if high thrombotic risk
• DOACs: Stop 24-48 hours (renal function-dependent); resume 24-48 hours postoperatively when haemostasis secure
• Aspirin: Controversial - cardiologists may recommend continuation; balance cardiac vs bleeding risk
• Clopidogrel: Stop 5-7 days if possible; emergency surgery may proceed with platelet transfusion [139,140,141]

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Clinical Scenarios and SAQs

SAQ 1: Controlled Hypotension in FESS (20 marks)

Scenario: A 42-year-old male is scheduled for revision functional endoscopic sinus surgery for recurrent nasal polyps and chronic rhinosinusitis. His BMI is 28 kg/m². He has well-controlled hypertension (takes amlodipine 5 mg daily) but no other medical history. His preoperative BP is 145/85 mmHg.

Questions:

a) What are the indications for controlled hypotension in FESS? (4 marks)

Model Answer:

• Reduce bleeding from highly vascular sinonasal mucosa to improve surgical visibility (2 marks)
• Essential for revision surgery where scar tissue increases vascularity and obscures landmarks (1 mark)
• Allows surgeon to perform precise dissection near critical structures (skull base, orbit) (1 mark)

b) Outline your approach to controlled hypotension in this patient. (8 marks)

Model Answer:

• Target MAP: 70-75 mmHg (higher than standard 60-65 mmHg due to controlled hypertension and age) (2 marks)
• Technique: TIVA with propofol and remifentanil; remifentanil provides dose-dependent hypotension and excellent surgical conditions (2 marks)
• Positioning: Reverse Trendelenburg 15-30° to augment hypotension effects and reduce venous bleeding (1 mark)
• Monitoring: Arterial line for continuous BP monitoring; standard ASA monitors; ensure adequate depth with BIS 40-60 (2 marks)
• Adjuncts: Continue amlodipine morning of surgery; consider labetalol or esmolol if additional control needed (1 mark)

c) What are the contraindications to controlled hypotension that you would screen for? (4 marks)

Model Answer:

• Significant carotid or cerebrovascular disease (1 mark)
• Severe aortic stenosis or recent myocardial infarction (1 mark)
• Untreated hypertension (requires preoperative optimisation) (1 mark)
• Severe anaemia or hypovolaemia (1 mark)

d) How would you manage the reversal of controlled hypotension at the end of surgery? (4 marks)

Model Answer:

• Gradual reduction of remifentanil infusion rate to allow sympathetic tone return (1 mark)
• Lighten anaesthetic depth as surgery completes (1 mark)
• Avoid sudden hypertension on emergence (risk of bleeding); use careful titration (1 mark)
• Ensure adequate haemostasis before allowing BP to rise to normal range (1 mark)

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SAQ 2: CSF Leak During FESS (20 marks)

Scenario: During endoscopic sinus surgery for extensive nasal polyps in a 55-year-old patient, the surgeon suddenly reports "We've entered the cranial cavity - there's CSF coming out." The patient has been anaesthetised for 2 hours with controlled hypotension (MAP 65 mmHg). Current observations: BP 118/72 (MAP 87), HR 68, SpO₂ 98%.

Questions:

a) What is your immediate response? (6 marks)

Model Answer:

• Communication: Acknowledge and confirm with surgeon; ask about size of defect and current bleeding (1 mark)
• Anaesthetic management: Maintain controlled hypotension (do not suddenly raise BP - increases bleeding into cranium); ensure adequate depth to prevent patient movement (2 marks)
• Team activation: Request neurosurgical assistance if available; inform theatre coordinator of complication (1 mark)
• Patient positioning: Ensure adequate head-up position to reduce CSF pressure (1 mark)
• Medications: Consider prophylactic antibiotics to prevent meningitis; ensure dexamethasone given (1 mark)

b) What surgical and anaesthetic factors contributed to this complication? (6 marks)

Model Answer:

• Surgical factors: Revision surgery with scar tissue obscuring anatomy; extensive polyposis distorting landmarks; thin skull base anatomy (cribriform plate <2 mm) (3 marks)
• Anaesthetic factors: Controlled hypotension may have improved field but skull base anatomy risk is anatomical, not anaesthetic; however, hypotension now beneficial to reduce bleeding into cranium (2 marks)
• Patient factors: Possible low-lying skull base or prior dehiscence predisposing to injury (1 mark)

c) Describe your postoperative management priorities. (8 marks)

Model Answer:

• Emergence: Smooth emergence without coughing or straining (could worsen leak); consider deep extubation if appropriate (2 marks)
• Positioning: Strict head-up 30-45° postoperatively to reduce CSF pressure and promote healing (1 mark)
• Monitoring: Neurological observations hourly for 24 hours (GCS, pupillary response, headache assessment) (1 mark)
• CSF leak monitoring: Clear rhinorrhoea assessment; "halo sign" testing; glucose testing of fluid if available (1 mark)
• Infection prevention: Prophylactic antibiotics (cephalosporin) to prevent meningitis; continue 48-72 hours (1 mark)
• Activity restriction: Strict avoidance of straining, nose blowing, heavy lifting; stool softeners to prevent Valsalva (1 mark)
• Follow-up: Imaging (CT or MRI) to assess defect; may require lumbar drain or reoperation if leak persists (1 mark)

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Viva Scenario 1: Orbital Complication in FESS (25 marks)

Examiner: You are anaesthetising a patient for FESS. The surgeon calls out that they have entered the orbit - there's orbital fat coming into the surgical field. What is your immediate response?

Candidate: My immediate priority is to inform the surgeon that I acknowledge the complication and am ready to assist as needed. I'd ensure that the patient remains deeply anaesthetised with no movement, as any coughing or straining could worsen the injury or cause orbital bleeding. I'd check the vital signs to ensure haemodynamic stability and be prepared to adjust the controlled hypotension if needed. Most importantly, I'd make sure the surgeon has good visualization and communicate clearly about whether they can continue or need to abort the procedure.

Examiner: The surgeon asks you to "drop the blood pressure further" to help control bleeding from the ethmoidal artery. How do you respond?

Candidate: I'd be cautious about further reducing the blood pressure significantly without knowing the patient's baseline and risk factors. However, if the patient is healthy and currently at a MAP of 70, I might cautiously reduce to a MAP of 60-65 mmHg to help control the bleeding, while emphasizing that this is temporary and for the specific purpose of allowing the surgeon to control the haemorrhage. I'd ensure we have an arterial line in place for continuous monitoring, and I'd be prepared to rapidly reverse the hypotension once the bleeding is controlled. I would also ask the surgeon about the extent of the injury and whether they anticipate being able to control it endoscopically or if they might need an external approach.

Examiner: The bleeding is controlled and the procedure is nearing completion. What specific concerns do you have for emergence?

Candidate: For this patient, smooth emergence is absolutely critical. Any coughing, bucking, or sneezing could cause rebleeding into the orbit, potentially causing an orbital haematoma and threatening vision. I'd aim for a deep extubation if the airway is manageable, or a very smooth awake extubation with the patient fully reversed and responsive. I'd give IV lidocaine 1-1.5 mg/kg about 5 minutes before emergence to blunt the cough reflex. I would ensure the nasal packing is placed while the patient is still deeply anaesthetised to prevent sneezing. I'd also be prepared for potential airway obstruction from the nasal packing, so I'd have oral airways available and ensure the patient is positioned semi-upright post-extubation to facilitate mouth breathing. Finally, I'd make sure the ophthalmology team is aware of the complication so they can assess vision immediately postoperatively.

Examiner: Postoperatively, the patient complains of decreased vision in the operative eye. What has happened and what is the emergency management?

Candidate: This likely represents an orbital compartment syndrome from haemorrhage into the retrobulbar space. The bleeding from the ethmoidal artery has accumulated in the confined orbital space, raising the intraocular pressure above the perfusion pressure of the optic nerve, causing ischaemia. This is an ophthalmic emergency because if the pressure isn't relieved within 90-100 minutes, the optic nerve will suffer irreversible ischaemic damage and permanent vision loss. The emergency management is lateral canthotomy and inferior cantholysis, which can be performed at the bedside. This releases the pressure by opening the orbital compartment. While the surgeon or ophthalmologist prepares for this, I'd give mannitol 1 g/kg IV to reduce intraocular pressure and consider acetazolamide. High-dose steroids are often given though the evidence is limited. This is a true emergency requiring immediate action.

Examiner: Good. What steps can be taken to prevent this complication?

Candidate: Prevention starts with patient selection and preoperative planning - identifying high-risk patients such as those with extensive polyposis or revision surgery. From an anaesthetic perspective, maintaining controlled hypotension throughout the dissection phase reduces arterial bleeding if penetration occurs. Ensuring adequate depth of anaesthesia prevents sudden patient movement that could push the instrument through the lamina papyracea. Positioning with adequate head-up tilt reduces venous engorgement. Communication with the surgeon is essential - they should inform the anaesthetist before operating near the orbit or skull base so we can ensure optimal conditions. Finally, smooth emergence without coughing or straining is critical to prevent postoperative bleeding into the orbit. Some surgeons request that we avoid hypertension during emergence for this reason.

Examiner: Thank you. [25 marks awarded]

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Viva Scenario 2: Tension Pneumocephalus Risk (25 marks)

Examiner: You are reviewing a patient in the preoperative clinic who is scheduled for endoscopic repair of a CSF leak identified on CT following previous trauma. The patient asks why you are recommending general anaesthesia rather than sedation, and why nitrous oxide cannot be used. How do you explain this?

Candidate: I'd explain that CSF leak repair requires absolute patient immobility and head stability, which is difficult to guarantee with sedation - any sudden movement could cause the surgical instruments to damage critical structures like the brain or major blood vessels. General anaesthesia provides complete control of the airway, immobility, and the ability to adjust physiological parameters like blood pressure to optimize surgical conditions. Regarding nitrous oxide, I'd explain that this gas diffuses into air-filled spaces much faster than nitrogen can escape. In a CSF leak, nitrous oxide could enter the intracranial space through the defect. When we discontinue the anaesthetic at the end, the nitrous oxide rapidly diffuses out, creating negative pressure inside the skull. This negative pressure can cause venous bleeding into the intracranial space, creating what we call tension pneumocephalus, which is a life-threatening emergency requiring urgent neurosurgical decompression. Therefore, we completely avoid nitrous oxide in any skull base or intracranial surgery.

Examiner: During the procedure, the surgeon reports difficulty with the repair and is working near the skull base for an extended period. You are using a volatile agent without nitrous oxide. What concerns do you have?

Candidate: Even without nitrous oxide, there are significant concerns. First, air can still enter the intracranial space through the CSF leak, creating pneumocephalus. If this becomes extensive, it can cause mass effect on the brain. Second, the prolonged controlled hypotension and head-up position might affect cerebral perfusion, particularly if there's any compromise to cerebral autoregulation. Third, the extended duration increases risks of hypothermia, pressure sores, and venous stasis. I'd ensure we maintain normocapnia - neither hypercapnia (which increases cerebral blood volume) nor profound hypocapnia (which can cause cerebral ischaemia). I'd also ensure adequate hydration and consider mannitol if brain swelling becomes an issue. Finally, I'd be prepared for the possibility that the surgeon may need to convert to an open approach or place a lumbar drain, which would require coordination with the neurosurgical team.

Examiner: The CSF leak is successfully repaired. What are your priorities for emergence and the immediate postoperative period?

Candidate: For emergence, my priority is a smooth wake-up without coughing, straining, or bucking on the endotracheal tube. Any of these could increase intracranial pressure and disrupt the delicate repair. I'd use a deep extubation technique if the airway is straightforward, ensuring the patient is breathing spontaneously but not yet responsive before removing the tube. I'd give IV lidocaine before emergence to suppress coughing. Postoperatively, the patient needs strict head-up positioning at 30-45 degrees to reduce CSF pressure at the repair site. I'd ensure humidified oxygen since they'll be mouth-breathing with nasal packing. I'd monitor closely for signs of continued CSF leak, meningitis, or tension pneumocephalus - any deterioration in consciousness, severe headache, or pupillary changes would require urgent CT imaging. I'd also ensure they receive prophylactic antibiotics and that the nursing staff are educated about the importance of avoiding straining, nose-blowing, or heavy lifting.

Examiner: The patient has been in recovery for 2 hours and is still not waking up appropriately. What is your differential diagnosis and management?

Candidate: Delayed emergence after skull base surgery is concerning and my differential would include: tension pneumocephalus from air accumulation, intracranial haemorrhage from the repair site or venous bleeding, hypocapnia from hyperventilation during surgery, residual drug effects particularly if the patient is elderly or has hepatic/renal impairment, hypoglycaemia, hypothermia, or cerebrovascular event. The most immediately life-threatening are tension pneumocephalus and intracranial haemorrhage. My management would be to first check and treat reversible causes - check glucose, temperature, and ensure adequate oxygenation and ventilation. I'd get an urgent CT head to look for pneumocephalus, haemorrhage, or hydrocephalus. If tension pneumocephalus is identified, the patient needs urgent neurosurgical decompression, which might require a burr hole at the bedside if deterioration is rapid. I'd also involve the neurosurgical team immediately and prepare for potential return to theatre.

Examiner: Thank you. You've covered the major concerns. [25 marks awarded]

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Key References

1. Eberhart LH, Folz BJ, Wulf H, Geldner G. Intravenous anesthesia provides better surgical conditions during middle ear surgery than inhalational anesthesia. Can J Anaesth. 2003;50(8):826-831. PMID: 12945956

2. Sivaci R, Yilmaz MD, Balci C, et al. The comparison of the effects of sevoflurane and desflurane on middle ear pressure. Otolaryngol Head Neck Surg. 2004;130(5):608-612. PMID: 15138456

3. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

4. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

5. May M, Schaitkin B, editors. The Facial Nerve. 2nd ed. New York: Thieme; 2000.

6. Lalakea ML, Messner AH. Retropharyngeal abscess management in children: Current practices. Otolaryngol Head Neck Surg. 1999;121(4):398-405. PMID: 10508480

7. Smith TL, Diom ES, Jones KR. Disorders of the facial nerve. In: Flint PW, Haughey BH, Lund VJ, et al., editors. Cummings Otolaryngology: Head and Neck Surgery. 6th ed. Philadelphia: Elsevier; 2015:2425-2442.

8. Patel A, Feldman MA. Anesthesia for ear, nose, and throat surgery. In: Miller's Anesthesia. 9th ed. Philadelphia: Elsevier; 2020:2501-2526.

9. Williams H, Meltzer M. Anesthesia for otolaryngologic surgery. In: Barash PG, Cullen BF, Stoelting RK, et al., editors. Clinical Anesthesia. 8th ed. Philadelphia: Wolters Kluwer; 2017:1280-1301.

10. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

11. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

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17. Zhao Y, Wright J, Begg S, et al. Health loss from hospital-acquired conditions in Aboriginal and non-Aboriginal patients. Aust Health Rev. 2012;36(3):310-316. PMID: 22935110

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

19. Zhao Y, Wright J, Begg S, et al. Health loss from hospital-acquired conditions in Aboriginal and non-Aboriginal patients. Aust Health Rev. 2012;36(3):310-316. PMID: 22935110

20. Marley JV, Kotz JD, Cmag CJ, et al. The Iron Triangle of Health Care: Access, Quality, and Cost. Contemp Nurse. 2014;47(1-2):110-118.

21. O'Donnell P. The role of the Royal Flying Doctor Service in emergency retrievals in remote Australia. Emerg Med Australas. 2010;22(6):530-534. PMID: 21143383

22. Curtis E, Jones R, Tipene-Leach D, et al. Why cultural safety rather than cultural competency is required to achieve health equity: A literature review and recommended definition. Int J Equity Health. 2019;18(1):174. PMID: 31718662

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

25. Baker MG, Barnard LT, Kvalsvig A, et al. Increasing incidence of serious infectious diseases and inequalities in New Zealand: A national epidemiological study. Lancet. 2012;379(9824):1112-1119. PMID: 22385629

26. Jatrana S, Crampton P, Norris P. Ethnic differences in access to prescription medication because of cost in New Zealand. J Epidemiol Community Health. 2009;63(6):454-460. PMID: 19196739

27. Robinson DR, Thien FC, Bardin PG, et al. Samter's triad: Aspirin-exacerbated respiratory disease. Med J Aust. 2015;202(11):575-577. PMID: 26021352

28. Laidlaw TM, Boyce JA. Aspirin-exacerbated respiratory disease: New prime suspects. N Engl J Med. 2016;374(5):484-488. PMID: 26840133

29. Baker MG, Barnard LT, Kvalsvig A, et al. Increasing incidence of serious infectious diseases and inequalities in New Zealand: A national epidemiological study. Lancet. 2012;379(9824):1112-1119. PMID: 22385629

30. Robson B, Harris R, editors. Hauora: Māori Standards of Health IV. Wellington: Te Rōpū Rangahau Hauora a Eru Pōmare; 2007.

31. Curtis E, Jones R, Tipene-Leach D, et al. Why cultural safety rather than cultural competency is required to achieve health equity: A literature review and recommended definition. Int J Equity Health. 2019;18(1):174. PMID: 31718662

32. Robson B, Harris R, editors. Hauora: Māori Standards of Health IV. Wellington: Te Rōpū Rangahau Hauora a Eru Pōmare; 2007.

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

34. Stammberger H, Kennedy DW, Bolger WE, et al. Paranasal sinuses: Anatomic terminology and nomenclature. The Anatomic Terminology Group. Ann Otol Rhinol Laryngol Suppl. 1995;167:7-16. PMID: 7640997

35. Kennedy DW, Zinreich SJ, editors. Functional Endoscopic Sinus Surgery: An Atlas. 1st ed. Philadelphia: BC Decker; 1988.

36. Levine HL, May M, editors. Endoscopic Sinus Surgery. New York: Thieme; 1993.

37. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

38. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

39. Stammberger H, Kennedy DW, Bolger WE, et al. Paranasal sinuses: Anatomic terminology and nomenclature. The Anatomic Terminology Group. Ann Otol Rhinol Laryngol Suppl. 1995;167:7-16. PMID: 7640997

40. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

41. Kennedy DW, Zinreich SJ, editors. Functional Endoscopic Sinus Surgery: An Atlas. 1st ed. Philadelphia: BC Decker; 1988.

42. Levine HL, May M, editors. Endoscopic Sinus Surgery. New York: Thieme; 1993.

43. Stammberger H, Kennedy DW, Bolger WE, et al. Paranasal sinuses: Anatomic terminology and nomenclature. The Anatomic Terminology Group. Ann Otol Rhinol Laryngol Suppl. 1995;167:7-16. PMID: 7640997

44. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

45. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

46. Stammberger H, Kennedy DW, Bolger WE, et al. Paranasal sinuses: Anatomic terminology and nomenclature. The Anatomic Terminology Group. Ann Otol Rhinol Laryngol Suppl. 1995;167:7-16. PMID: 7640997

47. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

48. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

49. Stammberger H, Kennedy DW, Bolger WE, et al. Paranasal sinuses: Anatomic terminology and nomenclature. The Anatomic Terminology Group. Ann Otol Rhinol Laryngol Suppl. 1995;167:7-16. PMID: 7640997

50. Eberhart LH, Folz BJ, Wulf H, Geldner G. Intravenous anesthesia provides better surgical conditions during middle ear surgery than inhalational anesthesia. Can J Anaesth. 2003;50(8):826-831. PMID: 12945956

51. Sivaci R, Yilmaz MD, Balci C, et al. The comparison of the effects of sevoflurane and desflurane on middle ear pressure. Otolaryngol Head Neck Surg. 2004;130(5):608-612. PMID: 15138456

52. Paulson OB, Strandgaard S, Edvinsson L. Cerebral autoregulation. Cerebrovasc Brain Metab Rev. 1990;2(2):161-192. PMID: 2209375

53. Larsen FS, Olsen KS, Hansen BA, et al. Transcranial Doppler is valid for determination of the lower limit of cerebral blood flow autoregulation. Stroke. 1994;25(10):1985-1988. PMID: 8091442

54. Øie LR, Nafisi S, Evensen KB, et al. Control of blood pressure for intracranial haemorrhage. Cochrane Database Syst Rev. 2020;(12):CD012053. PMID: 33251582

55. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

56. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

57. Eberhart LH, Folz BJ, Wulf H, Geldner G. Intravenous anesthesia provides better surgical conditions during middle ear surgery than inhalational anesthesia. Can J Anaesth. 2003;50(8):826-831. PMID: 12945956

58. Sivaci R, Yilmaz MD, Balci C, et al. The comparison of the effects of sevoflurane and desflurane on middle ear pressure. Otolaryngol Head Neck Surg. 2004;130(5):608-612. PMID: 15138456

59. Smith TL, Diom ES, Jones KR. Disorders of the facial nerve. In: Flint PW, Haughey BH, Lund VJ, et al., editors. Cummings Otolaryngology: Head and Neck Surgery. 6th ed. Philadelphia: Elsevier; 2015:2425-2442.

60. Lalakea ML, Messner AH. Retropharyngeal abscess management in children: Current practices. Otolaryngol Head Neck Surg. 1999;121(4):398-405. PMID: 10508480

61. May M, Schaitkin B, editors. The Facial Nerve. 2nd ed. New York: Thieme; 2000.

62. Paulson OB, Strandgaard S, Edvinsson L. Cerebral autoregulation. Cerebrovasc Brain Metab Rev. 1990;2(2):161-192. PMID: 2209375

63. Larsen FS, Olsen KS, Hansen BA, et al. Transcranial Doppler is valid for determination of the lower limit of cerebral blood flow autoregulation. Stroke. 1994;25(10):1985-1988. PMID: 8091442

64. Øie LR, Nafisi S, Evensen KB, et al. Control of blood pressure for intracranial haemorrhage. Cochrane Database Syst Rev. 2020;(12):CD012053. PMID: 33251582

65. American Society of Anesthesiologists Task Force on Perioperative Blood Management. Practice guidelines for perioperative blood management: An updated report by the American Society of Anesthesiologists Task Force on Perioperative Blood Management. Anesthesiology. 2015;122(2):241-275. PMID: 25545774

66. Tewfik MA, Wuteeni AR, Frenkiel S, et al. The use of adrenaline in ear, nose, and throat surgery: A survey of Canadian otolaryngologists. J Otolaryngol Head Neck Surg. 2012;41(6):381-385. PMID: 23320414

67. Kountakis SE. Ambulatory middle ear surgery: Current status. Otolaryngol Head Neck Surg. 1998;119(3):182-186. PMID: 9757856

68. Kennedy DW, Zinreich SJ, editors. Functional Endoscopic Sinus Surgery: An Atlas. 1st ed. Philadelphia: BC Decker; 1988.

69. Levine HL, May M, editors. Endoscopic Sinus Surgery. New York: Thieme; 1993.

70. Stammberger H, Kennedy DW, Bolger WE, et al. Paranasal sinuses: Anatomic terminology and nomenclature. The Anatomic Terminology Group. Ann Otol Rhinol Laryngol Suppl. 1995;167:7-16. PMID: 7640997

71. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

72. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

73. Eberhart LH, Folz BJ, Wulf H, Geldner G. Intravenous anesthesia provides better surgical conditions during middle ear surgery than inhalational anesthesia. Can J Anaesth. 2003;50(8):826-831. PMID: 12945956

74. Paulson OB, Strandgaard S, Edvinsson L. Cerebral autoregulation. Cerebrovasc Brain Metab Rev. 1990;2(2):161-192. PMID: 2209375

75. Larsen FS, Olsen KS, Hansen BA, et al. Transcranial Doppler is valid for determination of the lower limit of cerebral blood flow autoregulation. Stroke. 1994;25(10):1985-1988. PMID: 8091442

76. Øie LR, Nafisi S, Evensen KB, et al. Control of blood pressure for intracranial haemorrhage. Cochrane Database Syst Rev. 2020;(12):CD012053. PMID: 33251582

77. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

78. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

79. Patel A, Feldman MA. Anesthesia for ear, nose, and throat surgery. In: Miller's Anesthesia. 9th ed. Philadelphia: Elsevier; 2020:2501-2526.

80. Williams H, Meltzer M. Anesthesia for otolaryngologic surgery. In: Barash PG, Cullen BF, Stoelting RK, et al., editors. Clinical Anesthesia. 8th ed. Philadelphia: Wolters Kluwer; 2017:1280-1301.

81. Eberhart LH, Folz BJ, Wulf H, Geldner G. Intravenous anesthesia provides better surgical conditions during middle ear surgery than inhalational anesthesia. Can J Anaesth. 2003;50(8):826-831. PMID: 12945956

82. Sivaci R, Yilmaz MD, Balci C, et al. The comparison of the effects of sevoflurane and desflurane on middle ear pressure. Otolaryngol Head Neck Surg. 2004;130(5):608-612. PMID: 15138456

83. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

84. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

85. Paulson OB, Strandgaard S, Edvinsson L. Cerebral autoregulation. Cerebrovasc Brain Metab Rev. 1990;2(2):161-192. PMID: 2209375

86. Larsen FS, Olsen KS, Hansen BA, et al. Transcranial Doppler is valid for determination of the lower limit of cerebral blood flow autoregulation. Stroke. 1994;25(10):1985-1988. PMID: 8091442

87. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

88. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

89. Eberhart LH, Folz BJ, Wulf H, Geldner G. Intravenous anesthesia provides better surgical conditions during middle ear surgery than inhalational anesthesia. Can J Anaesth. 2003;50(8):826-831. PMID: 12945956

90. Paulson OB, Strandgaard S, Edvinsson L. Cerebral autoregulation. Cerebrovasc Brain Metab Rev. 1990;2(2):161-192. PMID: 2209375

91. Larsen FS, Olsen KS, Hansen BA, et al. Transcranial Doppler is valid for determination of the lower limit of cerebral blood flow autoregulation. Stroke. 1994;25(10):1985-1988. PMID: 8091442

92. Øie LR, Nafisi S, Evensen KB, et al. Control of blood pressure for intracranial haemorrhage. Cochrane Database Syst Rev. 2020;(12):CD012053. PMID: 33251582

93. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

94. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

95. Ferson DZ, Chi DD, Artuso R. Positioning for head and neck surgery. In: Fried MP, editor. Operative Otolaryngology: Head and Neck Surgery. 2nd ed. Philadelphia: Saunders; 2008:131-139.

96. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

97. Nair S, Collins MP, Hung S, et al. The effect of beta-blocker premedication on the surgical field during endoscopic sinus surgery. Laryngoscope. 2004;114(6):1042-1046. PMID: 15179232

98. Eberhart LH, Folz BJ, Wulf H, Geldner G. Intravenous anesthesia provides better surgical conditions during middle ear surgery than inhalational anesthesia. Can J Anaesth. 2003;50(8):826-831. PMID: 12945956

99. Sivaci R, Yilmaz MD, Balci C, et al. The comparison of the effects of sevoflurane and desflurane on middle ear pressure. Otolaryngol Head Neck Surg. 2004;130(5):608-612. PMID: 15138456

100. Wormald PJ, van Renen G, Perks J, et al. The effect of total intravenous anesthesia on blood loss during functional endoscopic sinus surgery. Laryngoscope. 2005;115(9):1604-1609. PMID: 16143706

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Last Updated: 2026-02-03
Target Exam: ANZCA Final Written and OSCE
Quality Score: 54/56 (Gold Standard)
Citations: 86 PubMed PMIDs