Preparation, anaesthetic management and post operative complications of FESS and the tole of hypotensive anaesthesia for md anaesthesia exam with tab,e viva questions
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Anaesthesia for FESS (Functional Endoscopic Sinus Surgery)
MD Anaesthesia Exam - Complete Study Guide
1. INTRODUCTION
FESS is performed for chronic rhinosinusitis, nasal polyposis, recurrent acute sinusitis, and sinonasal tumours. It involves endoscopic removal of diseased tissue within the ostiomeatal complex, ethmoid sinuses, maxillary, sphenoid, and frontal sinuses using a rigid nasal endoscope. The surgery is performed in a shared airway, in close proximity to the orbit, skull base, and carotid artery, making anaesthetic management critical.
Key anaesthetic challenges:
- Shared airway with ENT surgeon
- Absolute need for a bloodless, dry surgical field (bleeding obscures the endoscopic view and risks serious complications)
- Systemic absorption of vasoconstrictors
- Risk of serious orbital and intracranial complications
2. PREOPERATIVE ASSESSMENT AND PREPARATION
2.1 History and Examination
| System | Key Assessment Points |
|---|---|
| Airway | Nasal obstruction, septal deviation, polyps (may affect post-op airway); assess mouth opening and neck mobility |
| Cardiovascular | Coronary artery disease, peripheral artery disease, arrhythmias - relevant because sympathomimetic vasoconstrictors are used; hypertension (right-shifts autoregulation curve) |
| Respiratory | Asthma (30-70% of patients with nasal polyps have concomitant asthma - Samter's triad: asthma + nasal polyps + aspirin sensitivity); COPD; OSA |
| Drugs | NSAIDs, anticoagulants, antiplatelets - stop as per protocol; ACE inhibitors/ARBs (day of surgery); beta-blockers (document - alpha agonist constrictors may cause rebound hypertension) |
| Allergies | Aspirin/NSAID sensitivity (Samter's triad) |
| Previous surgery | Previous FESS or sinus surgery changes anatomy significantly; increased complication risk |
2.2 Investigations
| Investigation | Indication |
|---|---|
| CT sinuses (coronal + axial) | Mandatory - must be available in theatre throughout surgery; identifies anatomical variants (Haller cells, Onodi cells, dehiscent lamina papyracea); without imaging, orbital/intracranial complications increase |
| FBC | Baseline haemoglobin (minimum 10 g/dL for hypotensive anaesthesia); platelet count |
| Coagulation studies | If on anticoagulants; bleeding disorder suspected |
| ECG | If cardiovascular disease or age >40 |
| Spirometry/PFTs | If significant asthma/COPD |
2.3 Preoperative Optimisation
- Asthma: optimise with bronchodilators; avoid aspirin-containing compounds
- Hypertension: should be well-controlled; chronic hypertensives tolerate hypotension poorly (autoregulatory curve shifted rightward)
- Nasal steroids: continue perioperatively to reduce polyp vascularity
- Anticoagulants: stop as per protocol (warfarin stop 5 days, NOACs 24-48 hours, aspirin 7 days)
- Premedication: anxiolysis with midazolam 1-2 mg IV; avoid heavy sedation; antiemetic (ondansetron 4 mg); antisialogogue (glycopyrrolate 0.2 mg) may reduce secretions
- Explain: consent to include potential conversion to GA if done under LA/sedation; post-op nasal packing
3. ANAESTHETIC MANAGEMENT
3.1 Choice of Anaesthetic Technique
| Technique | Indications | Disadvantages |
|---|---|---|
| GA (preferred) | Complex/extended FESS; revision surgery; patients unable to cooperate; children | Requires careful airway management; PONV risk |
| LA + sedation | Simple unilateral procedures; ASA III-IV patients where GA risk high | Less control; patient movement; limited operating time |
GA is the standard of care for most FESS - as the scope of procedures increased, GA became preferred because it provides immobility, a controlled airway, and ability to use controlled hypotension. - Barash Clinical Anesthesia, 9e
3.2 Monitoring
| Monitor | Rationale |
|---|---|
| Standard ASA monitors (NIBP, SpO2, ECG, EtCO2) | Mandatory |
| Invasive arterial line (intra-arterial BP) | If controlled hypotension planned, elderly, cardiac disease, prolonged surgery |
| Temperature | Hypothermia reduces MAC and cardiac output |
| Bispectral Index (BIS) / depth of anaesthesia | Useful with TIVA; target BIS 40-60 |
| Urine output (urinary catheter) | If prolonged surgery or controlled hypotension |
| Neuromuscular monitoring | If muscle relaxants used |
3.3 Induction
Drug choice:
| Drug | Role | Dose |
|---|---|---|
| Propofol | Preferred induction agent; reduces PONV; smooth induction | 1.5-2.5 mg/kg IV |
| Fentanyl | Analgesia; attenuates intubation response | 1-2 mcg/kg IV |
| Midazolam | Pre-induction anxiolysis | 1-2 mg IV |
| Rocuronium / Vecuronium | Muscle relaxation for intubation | 0.6 / 0.1 mg/kg |
| Lignocaine | Attenuates intubation pressor response | 1.5 mg/kg IV 3 min before intubation |
Airway management:
- Cuffed oral RAE (Ring-Adair-Elwyn) ETT - preferred; keeps circuit away from surgical field; fixation on chin
- LMA (ProSeal/Supreme) - used in some centres for short, simple procedures; risk of losing airway; not preferred if surgeon needs full nasal access or throat packing used
- Reinforced/armoured ETT - acceptable alternative to RAE
- Throat pack: routinely inserted to prevent blood/secretion ingestion (must be counted, labelled, and documented - MUST be removed before extubation)
3.4 Positioning
- Head-up tilt 15-20 degrees (reverse Trendelenburg):
- Reduces venous congestion in nasal mucosa
- Reduces arterial blood pressure modestly
- Reduces mucosal oozing
- Note: risk of venous air embolism (rare) and venous pooling in lower limbs
3.5 Vasoconstriction (Local Anaesthetic + Vasoconstrictor Application)
Always applied by the surgeon before commencing surgery.
| Agent | Concentration/Dose | Mechanism | Risks |
|---|---|---|---|
| Cocaine (topical) | 4-10% solution; max 3 mg/kg | NA reuptake inhibition + direct vasoconstriction | Hypertension, tachycardia, arrhythmias, cocaine toxicity; do NOT combine with adrenaline |
| Lignocaine + Adrenaline | 1% lignocaine + 1:100,000 adrenaline (submucosal injection) | Local anaesthesia + alpha-1 vasoconstriction | Systemic absorption: tachycardia, hypertension, arrhythmias |
| Phenylephrine (topical) | 0.5% | Alpha-1 agonist | Reflex bradycardia, hypertension; dangerous in patients on beta-blockers (unopposed alpha causes severe hypertension) |
| Oxymetazoline (topical) | 0.05-0.1% | Alpha-1/2 agonist | Systemic absorption minimal compared to above |
| Adrenaline (topical) | 1:1000 soaked pledgets | Alpha + beta adrenergic | Hypertension, tachycardia, arrhythmias, especially under volatile anaesthesia |
Important: Systemic absorption of vasoconstrictors can cause hypertension, hypotension, tachycardia, bradycardia, and arrhythmias. Patients on beta-blockers are at particular risk of severe hypertension from alpha-agonists. Prompt treatment is required.
3.6 Maintenance
Two options: Volatile-based GA vs TIVA
| Feature | Volatile (Sevoflurane/Isoflurane) | TIVA (Propofol + Remifentanil) |
|---|---|---|
| Surgical field quality | Good | Superior - better bloodless field |
| PONV | Higher incidence | Lower incidence |
| Coughing on emergence | More common | Less common - smooth emergence |
| Controlled hypotension | Feasible (dose-dependent vasodilation) | More precise control |
| Cost | Lower | Higher |
| Depth of anaesthesia monitoring | Less critical | BIS monitoring recommended |
| Recovery | Similar | Faster, cleaner |
TIVA with propofol + remifentanil is the preferred maintenance technique for FESS in most centres. Remifentanil provides excellent intraoperative analgesia, dose-titrable hypotension, haemodynamic stability, and ultrashort offset allowing rapid clean emergence.
Typical TIVA regime:
- Propofol: 4-8 mg/kg/h (TCI: effect site 2-4 mcg/mL)
- Remifentanil: 0.1-0.3 mcg/kg/min (TCI: effect site 2-5 ng/mL)
- Air/O2 mixture (FiO2 0.4-0.5)
- Avoid N2O - increases PONV, may enter sinuses
Ventilation:
- Mild hypocapnia (PaCO2 35-40 mmHg) - hyperventilation causes cerebral vasoconstriction, which can worsen cerebral hypoperfusion during hypotensive anaesthesia; keep PetCO2 35-40 mmHg
- IPPV with low tidal volumes (6-8 mL/kg) + PEEP 5 cmH2O
Fluid management:
- Restrict IV fluids (avoid fluid overload which increases venous bleeding)
- Typically 500-1000 mL crystalloid for a 2-hour procedure
3.7 Emergence and Extubation
Critical phase - coughing and straining on emergence causes venous congestion, increases bleeding, and risks disruption of surgical haemostasis.
Strategies for smooth emergence:
- Stop remifentanil 5-10 minutes before expected end
- Ensure adequate analgesia with paracetamol/NSAIDs/fentanyl before emergence
- Deep extubation (if airway is safe and not at aspiration risk) - reduces bucking
- Lignocaine 1.5 mg/kg IV 3-5 minutes before extubation - reduces coughing
- Ensure throat pack is removed (documented), oropharynx suctioned before extubation
- Extubate in head-up position
- Dexmedetomidine 0.5 mcg/kg over 10 min before emergence reduces emergence agitation and coughing
- Propofol 0.25-0.5 mg/kg IV at end of surgery reduces emergence coughing
Extubation criteria:
- Fully awake, following commands
- Adequate muscle power (TOF ratio >0.9)
- Stable haemodynamics
- Throat pack removed and accounted for
4. HYPOTENSIVE ANAESTHESIA IN FESS
4.1 Definition and Rationale
Deliberate (controlled) hypotension is the intentional reduction of MAP to a predetermined target to reduce intraoperative bleeding and improve the quality of the surgical field.
In FESS, even modest bleeding obscures the endoscopic view and:
- Increases operative time
- Increases risk of orbital and intracranial complications (surgeon cannot see landmarks)
- Increases blood loss and transfusion requirements
- Reduces surgical precision
Surgical field quality is typically graded using the Boezaart scale (0-5):
| Grade | Description |
|---|---|
| 0 | No bleeding - cadaveric field |
| 1 | Slight bleeding - no suctioning required |
| 2 | Slight bleeding - occasional suction required |
| 3 | Moderate bleeding - frequent suction required |
| 4 | Moderate bleeding - suction constantly required; field visible only momentarily |
| 5 | Severe bleeding - uncontrollable; surgery impossible |
| Target | Grade 1-2 |
4.2 Physiology
MAP = Cardiac Output × Systemic Vascular Resistance (SVR)
- Reducing MAP by reducing SVR (vasodilation) or reducing cardiac output (reduced HR, contractility, venous return) or both
- Organ autoregulation: most organs maintain blood flow over a MAP range of 50-150 mmHg
- In chronic hypertensives: autoregulatory curve shifts right - minimum safe MAP is higher
- Cerebral autoregulation is lost below MAP of approximately 50 mmHg in healthy adults
4.3 Target Blood Pressure
| Patient | Target MAP | Systolic BP |
|---|---|---|
| Healthy adult (ASA I-II) | 50-65 mmHg | 80-90 mmHg |
| Elderly patients | 65-80 mmHg | >90 mmHg |
| Chronic hypertensives | 70-80 mmHg (no more than 30% below resting MAP) | Minimum 80-90 mmHg |
| General rule | MAP reduced by no more than 30% from baseline | - |
Evidence from Frontiers RCT on FESS: A 30% reduction in MAP from baseline improved surgical field quality and reduced intraoperative bleeding without clinically significant cerebral oxygen desaturation (rSO2 decreased by only ~5%, remaining within safe levels).
4.4 Techniques to Achieve Controlled Hypotension
A. Patient Positioning
- Head-up tilt 15-20 degrees (venous drainage, reduces mucosal congestion)
- Simple, safe, first-line measure
B. Anaesthetic Agents
| Agent | Mechanism | Notes |
|---|---|---|
| Propofol (TIVA) | Vasodilation + cardiac depression | Preferred; predictable depth; reduces PONV |
| Sevoflurane/Isoflurane | Dose-dependent vasodilation; reduces SVR | Effective; sevoflurane preferred (less pungent, less arrhythmogenic) |
| Remifentanil | Sympatholysis, vagotonic (bradycardia + hypotension); dose-titrable | Excellent for FESS; infusion easily titrated; used in propofol/remifentanil TIVA |
| N2O | Avoid | No hypotensive benefit; increases PONV |
C. Vasodilators
| Drug | Dose | Mechanism | Advantages | Disadvantages |
|---|---|---|---|---|
| Sodium Nitroprusside (SNP) | 0.5-10 mcg/kg/min IV infusion | NO donor; direct arteriolar + venodilator | Rapid onset/offset; titratable; highly potent | Cyanide toxicity (>10 mcg/kg/min or >10 mg/kg total); tachycardia; reflex tachycardia; coronary steal; requires strict monitoring |
| GTN (Nitroglycerin) | 0.5-5 mcg/kg/min IV | NO donor; predominantly venodilator | Coronary vasodilation (beneficial in CAD) | Less arterial effect than SNP; tachycardia |
| Nicardipine | 5-15 mcg/kg/min IV | Calcium channel blocker; arteriolar vasodilator | Maintains cardiac output; no cyanide risk; good for patients with CAD | May cause reflex tachycardia |
| Hydralazine | 5-20 mg IV bolus | Direct arteriolar vasodilator | Oral availability; familiar drug | Slow onset; tachycardia; unpredictable; not ideal for intraoperative use |
D. Beta-Blockers
| Drug | Dose | Notes |
|---|---|---|
| Esmolol | 500 mcg/kg bolus then 50-200 mcg/kg/min infusion | Short-acting beta-1 blocker; reduces HR and CO; also reduces bleeding via reduced cardiac output; combined with nicardipine or SNP |
| Metoprolol | 1-5 mg IV bolus | Longer-acting; less titratable |
| Labetalol | 5-20 mg IV boluses | Alpha + beta blocker; useful in hypertensive patients |
E. Alpha-2 Agonists
| Drug | Dose | Notes |
|---|---|---|
| Dexmedetomidine | 0.5-1 mcg/kg loading over 10 min; 0.2-0.7 mcg/kg/h maintenance | Central sympatholysis; reduces HR and MAP; reduces anaesthetic requirements; also smooth emergence; evidence-based for FESS (Shams et al., 2013, PMC3737695) |
| Clonidine | 1-3 mcg/kg IV | Longer-acting; preoperative use |
Evidence: Both dexmedetomidine and esmolol with sevoflurane are safe and effective for controlled hypotension during FESS, providing ideal surgical fields. - Shams et al., 2013
F. Combined Technique (Most Commonly Used in Practice)
TIVA (Propofol + Remifentanil) + Dexmedetomidine/Esmolol
This is the most evidence-backed approach:
- Propofol TCI + Remifentanil TCI provides the bulk of hypotension
- Dexmedetomidine or Esmolol added for adjunct heart rate and BP control
- Head-up 15 degrees
- Surgeon applies topical vasoconstrictor
4.5 Contraindications to Hypotensive Anaesthesia
| Absolute Contraindications | Relative Contraindications |
|---|---|
| Uncontrolled hypertension | Controlled hypertension |
| Severe coronary artery disease / recent MI | Mild-moderate CAD (raise target MAP to 70-80) |
| Severe left ventricular dysfunction | Peripheral vascular disease |
| Haemodynamically significant valvular disease | Cerebrovascular disease |
| Severe anaemia (Hb <10 g/dL) | Elderly (>70 years) |
| Hypovolaemia / shock | Diabetes mellitus |
| Severe renal/hepatic insufficiency | Renal insufficiency |
| Glaucoma (SNP/GTN increase IOP) | Poorly controlled diabetes |
| Sickle cell disease | Inadequate monitoring equipment |
| Lack of monitoring capability | Inexperienced anaesthetist |
| Increased intracranial pressure | - |
4.6 Monitoring During Hypotensive Anaesthesia
| Monitor | Purpose |
|---|---|
| Intra-arterial line | Beat-to-beat BP monitoring; mandatory when MAP target <65 mmHg |
| ECG (5-lead with ST analysis) | Ischaemia detection |
| SpO2 and EtCO2 | Adequacy of ventilation/oxygenation |
| Urine output (catheter) | Renal perfusion (>0.5 mL/kg/h) |
| Temperature | Hypothermia worsens coagulopathy |
| BIS/depth of anaesthesia | Prevent awareness (anaesthesia depth may appear lighter when BP falls) |
| Cerebral oximetry (rSO2) | Optional; gold standard for cerebral perfusion monitoring during deliberate hypotension |
5. POSTOPERATIVE COMPLICATIONS
5.1 Intraoperative Complications
| Complication | Details | Prevention/Management |
|---|---|---|
| Orbital complications | Most feared; include: periorbital haematoma, orbital haematoma, diplopia, epiphora, blindness (optic nerve/artery injury), medial rectus injury | Meticulous technique; CT images in theatre; intraoperative navigation |
| Intracranial complications | CSF leak (most common - 0.1-0.5%), meningitis, intracranial haemorrhage | Recognition; immediate neurosurgical consultation |
| Bleeding | Average EBL 100-300 mL; massive haemorrhage if ICA injury | Controlled hypotension; vasoconstrictors; careful technique |
| ICA injury | Rare but catastrophic (carotid artery is adjacent to sphenoid sinus) | Pack and transfer to vascular surgery; mortality high |
| Arrhythmias | From vasoconstrictor systemic absorption | Monitor ECG; treat with esmolol/atropine as appropriate |
| Hypertensive crisis | From vasoconstrictor + beta-blocker interaction (unopposed alpha) | Avoid phenylephrine in beta-blocked patients; treat with phentolamine or nitroprusside |
| Venous air embolism | Rare; related to head-up position and venous sinuses | Reduce head elevation; treat VAE protocol |
5.2 Postoperative Complications
| Complication | Incidence/Details | Management |
|---|---|---|
| PONV | High incidence (blood swallowing, opioid use) | Multimodal prophylaxis: ondansetron + dexamethasone + TIVA (propofol); 5-HT3 antagonists; avoid opioids where possible |
| Pain | Usually mild-moderate | Multimodal: paracetamol + NSAIDs (if no contraindication) + low-dose opioid; avoid high-dose opioids |
| Nasal bleeding | Early (primary) or delayed (reactionary/secondary) | Nasal packing in theatre; if persistent - examination under anaesthesia; embolisation |
| Nasal obstruction / crusting | From nasal packing and mucosal swelling | Nasal saline irrigation from post-op day 1; packing removal at 24-48 hours |
| Orbital emphysema | Air forced into orbit when patient blows nose | Instruct patient not to blow nose for 2 weeks |
| Epiphora | Damage to nasolacrimal duct | Ophthalmology referral; dacryocystorhinostomy if persistent |
| Anosmia | Damage to olfactory fibres at cribriform plate | Often temporary; may be permanent |
| Meningitis | CSF leak, infection | Prophylactic antibiotics if CSF leak; neurosurgical consultation |
| Throat pack retained | Critical if forgotten | Count, label, and document throat pack; MUST be on anaesthetic chart and on WHO checklist |
| Post-obstructive pulmonary oedema | Airway obstruction from blood/secretions during emergence | Avoid laryngospasm; suction; post-op oxygen therapy |
| Airway compromise | Nasal packing + pharyngeal swelling; patients are mouth-breathers postoperatively | Monitor in recovery; supplemental oxygen; sit upright; avoid sedatives |
| Toxic shock syndrome | From nasal packing (especially non-absorbable packing >48 hours) | Use impregnated or absorbable packs; remove within 24-48 hours; antibiotic prophylaxis |
6. SUMMARY TABLE: DRUGS USED IN FESS ANAESTHESIA
| Phase | Drug | Dose | Purpose |
|---|---|---|---|
| Pre-induction | Midazolam | 1-2 mg IV | Anxiolysis |
| Ondansetron | 4 mg IV | PONV prophylaxis | |
| Glycopyrrolate | 0.2 mg IV | Antisialogogue | |
| Induction | Propofol | 1.5-2.5 mg/kg | Induction; reduces PONV |
| Fentanyl | 1-2 mcg/kg | Analgesia; attenuates pressor response | |
| Lignocaine | 1.5 mg/kg IV | Attenuates intubation pressor response | |
| Rocuronium | 0.6 mg/kg | Intubation | |
| Maintenance | Propofol infusion | 4-8 mg/kg/h | TIVA maintenance |
| Remifentanil infusion | 0.1-0.3 mcg/kg/min | Analgesia + hypotension | |
| Dexmedetomidine | 0.5-1 mcg/kg load, 0.2-0.7 mcg/kg/h | Adjunct hypotension; smooth emergence | |
| Esmolol | 50-200 mcg/kg/min | Rate control; adjunct hypotension | |
| SNP (if needed) | 0.5-3 mcg/kg/min | Potent vasodilatation | |
| Topical (surgeon) | Cocaine | 4% solution | Vasoconstriction + local anaesthesia |
| Adrenaline (1:80,000-1:200,000) | Pledgets | Vasoconstriction | |
| Lignocaine + adrenaline | 1% + 1:100,000 | Submucosal injection | |
| Emergence | Lignocaine | 1.5 mg/kg IV | Prevent coughing |
| Propofol (small bolus) | 0.25 mg/kg | Smooth emergence | |
| Paracetamol | 1 g IV | Post-op analgesia | |
| Dexamethasone | 8 mg IV | PONV + oedema reduction | |
| Post-op | Ondansetron | 4 mg IV/oral | PONV |
| Diclofenac/Ibuprofen | Standard doses | Analgesia (if no contraindication) |
7. VIVA QUESTIONS AND MODEL ANSWERS
Q1. What is the main anaesthetic challenge in FESS and how do you address it?
A: The main challenge is maintaining a bloodless, dry surgical field to allow the surgeon to visualise the narrow endoscopic anatomy safely. Even mild bleeding obscures the view and risks catastrophic orbital or intracranial complications. I address this by: (1) using TIVA with propofol and remifentanil which gives better field quality than volatile anaesthesia; (2) applying deliberate controlled hypotension (MAP 50-65 mmHg or 30% below baseline); (3) positioning with 15-degree head-up tilt; and (4) ensuring the surgeon applies topical vasoconstrictors (cocaine/adrenaline) before commencing.
Q2. What is controlled hypotensive anaesthesia? What are its targets in FESS?
A: Deliberate (controlled) hypotension is the intentional lowering of MAP to a predetermined level to reduce surgical bleeding. MAP is a product of cardiac output and SVR, and can be reduced by lowering either or both. For FESS in a healthy adult: target MAP 50-65 mmHg or no more than 30% below the patient's baseline MAP, with a minimum of 50 mmHg. In the elderly or hypertensives, target is higher (65-80 mmHg). The endpoint is Boezaart grade 1-2 surgical field.
Q3. What are the contraindications to hypotensive anaesthesia?
A: Absolute: severe CAD/recent MI, severe cardiac failure, severe anaemia (Hb <10), uncontrolled hypertension, haemodynamic instability, increased ICP, sickle cell disease, glaucoma (SNP/GTN raise IOP), renal/hepatic failure, lack of monitoring (invasive arterial line). Relative: elderly, controlled hypertension, diabetes, peripheral vascular disease, cerebrovascular disease - in these, raise the target MAP.
Q4. TIVA versus volatile anaesthesia for FESS - which do you prefer and why?
A: TIVA with propofol and remifentanil is preferred for several reasons: (1) significantly lower PONV - important since blood swallowing is common; (2) better surgical field quality - propofol + remifentanil gives superior bloodless field compared to volatiles alone; (3) smooth, calm emergence with less coughing - prevents venous congestion and post-op bleeding; (4) more precise control of MAP via remifentanil infusion; (5) faster clear-headed recovery. BIS monitoring is recommended with TIVA. The disadvantage is cost and requirement for pumps/TCI.
Q5. How do you manage emergence in FESS to avoid post-op bleeding?
A: Coughing and straining on emergence increase venous pressure and can disrupt surgical haemostasis. My approach: (1) ensure adequate multimodal analgesia (paracetamol IV, NSAIDs, low-dose fentanyl) before stopping remifentanil; (2) give lignocaine 1.5 mg/kg IV 3-5 min before extubation; (3) confirm throat pack removed; (4) suction oropharynx gently; (5) consider deep extubation if airway safe; (6) dexmedetomidine 0.5 mcg/kg 10 min before end of surgery; (7) extubate head-up; (8) avoid neostigmine (causes increased secretions and nausea) - use sugammadex if reversal needed.
Q6. What is Samter's triad and why is it relevant to FESS anaesthesia?
A: Samter's triad (Aspirin-Exacerbated Respiratory Disease) = asthma + nasal polyps + aspirin/NSAID sensitivity. It is relevant because: (1) the patient population undergoing FESS has a high prevalence; (2) aspirin and NSAIDs (commonly used for post-op pain) must be avoided; (3) intraoperative bronchospasm may occur; (4) these patients often have more severe/recurrent polyposis requiring revision FESS. Paracetamol and opioids are used for post-op analgesia instead of NSAIDs.
Q7. What are the risks of cocaine as a nasal vasoconstrictor?
A: Cocaine inhibits noradrenaline reuptake at sympathetic nerve terminals, causing intense vasoconstriction and systemic sympathomimetic effects. Risks include: hypertension, tachycardia, VT/VF (sensitises myocardium to catecholamines), CNS stimulation and seizures. Maximum dose is 3 mg/kg. Must NOT be combined with adrenaline (additive catecholamine effect). Contraindicated in patients with CAD, arrhythmias. Under volatile anaesthesia, arrhythmia threshold is lower (halothane worst, sevoflurane safest).
Q8. What happens if the throat pack is not removed before extubation?
A: Retained throat pack is a critical airway emergency. It causes immediate post-extubation airway obstruction. Prevention: count, label and document the throat pack at insertion; include removal on the WHO sign-out checklist; do not extubate until pack removal is confirmed by both anaesthetist and surgeon; tape a reminder to the patient's forehead in some centres. It must be on the anaesthetic chart.
Q9. How would you manage an unexpected orbital haematoma developing intraoperatively?
A: This is an ophthalmic emergency. Intraoperative signs: proptosis, firmness of globe, loss of red reflex, fixed dilated pupil. Management: (1) stop surgery immediately; (2) call ophthalmologist; (3) lateral canthotomy and cantholysis to decompress orbit (within 90-120 min to prevent permanent visual loss); (4) maintain normotension; (5) avoid increases in intraocular pressure (no bucking, no PEEP, head-up); (6) steroids (dexamethasone); (7) transfer to ophthalmic OR if needed.
Q10. What are the advantages of remifentanil in FESS?
A: Remifentanil is uniquely suited to FESS: (1) ultra-short context-sensitive half-time (~3-5 min regardless of infusion duration) allows rapid offset; (2) produces dose-dependent sympatholysis and hypotension - easily titratable for controlled hypotension; (3) reduces anaesthetic requirements (reduces propofol dose); (4) attenuates airway reflexes - less coughing; (5) produces smooth, still surgical conditions (immobility); (6) fast, clear-headed emergence. Disadvantage: no post-op analgesia - must ensure multimodal analgesia is in place before stopping infusion to prevent acute pain.
Q11. Classify the methods of achieving controlled hypotension.
A:
- Positioning - head-up tilt (venous pooling)
- Anaesthetic agents - volatile (dose-dependent vasodilation), propofol, remifentanil
- Vasodilators - arteriolar: SNP, hydralazine, nicardipine; venodilators: GTN; mixed: phentolamine
- Beta-blockers - esmolol, labetalol (also alpha-block), metoprolol
- Alpha-2 agonists - dexmedetomidine, clonidine (central sympatholysis)
- Ganglionic blockers - trimetaphan (historical; no longer used)
- Combined techniques - most effective; e.g. TIVA + dexmedetomidine/esmolol
Q12. How do you manage a patient on beta-blockers scheduled for FESS where cocaine or phenylephrine will be used?
A: This is a potential hypertensive crisis situation - beta-blockers block the beta-receptors, leaving alpha-adrenergic vasoconstriction unopposed, causing severe hypertension and possible pulmonary oedema. Approach: (1) discuss with surgeon - use adrenaline instead of phenylephrine (has beta-2 action); avoid cocaine where possible; (2) continue beta-blockers on day of surgery; (3) have IV labetalol or phentolamine/sodium nitroprusside ready; (4) invasive arterial monitoring; (5) treat acute hypertension promptly with nitroprusside or phentolamine.
8. QUICK REFERENCE TABLE: KEY FACTS FOR EXAM
| Topic | Key Fact |
|---|---|
| Anaesthetic technique of choice | TIVA with propofol + remifentanil |
| Airway device of choice | Cuffed oral RAE ETT |
| Target MAP in healthy adult | 50-65 mmHg (not more than 30% reduction from baseline) |
| Minimum Hb for hypotensive anaesthesia | 10 g/dL |
| Minimum MAP absolute | 50 mmHg (ASA I); 80 mmHg in elderly |
| Surgical field grading | Boezaart scale 0-5; target grade 1-2 |
| PONV prophylaxis | Ondansetron + dexamethasone + TIVA |
| Head position | 15-20 degree head-up |
| Avoid | N2O (PONV, sinus distension), aspirin in Samter's triad |
| Most feared complication | Orbital haematoma / blindness; ICA injury |
| Critical patient safety step | Throat pack documentation and removal |
| Best evidence-based drug for adjunct hypotension | Dexmedetomidine or esmolol (Shams et al. 2013) |
| SNP maximum safe dose | 10 mcg/kg/min; total <10 mg/kg (cyanide risk) |
| Cocaine max dose | 3 mg/kg; do NOT combine with adrenaline |
Sources: Barash Clinical Anesthesia 9e; Scott-Brown's Otorhinolaryngology Head & Neck Surgery Vol 1; Miller's Anesthesia 10e; Shams T et al. Induced hypotension for FESS. PMC3737695, 2013; Frontiers RCT on deliberate hypotension and rSO2 in FESS, 2021; UKZN Controlled Hypotensive Anaesthesia resource.
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