2024.2 Day 1 VIVA 2

General Anaesthesia and Sedation

A 35-year-old woman is booked for a laparoscopy +/- excision of endometriosis in Scenarioville. She is otherwise fit and healthy. She takes Escitalopram 20mg daily. Her BMI is 32. She is very concerned about prolonged and severe post-operative nausea and vomiting (PONV) after a previous day surgery laparoscopy resulted in an unplanned overnight admission. She has had a previous caesarean section under spinal anaesthesia with no issues. This patient is very anxious and wants to know if there are any strategies to reduce her risk of PONV this time.

How would you explore her history of post-operative nausea and vomiting and assess her risk for this procedure?

• History Exploration:

  • Detail prior PONV event:

    • Onset (early/late), severity (required admission), triggers (e.g., opioids, volatile agents), what antiemetics were tried.

  • Confirm if ondansetron was ineffective → may influence prophylaxis plan.

• Risk Stratification (Apfel score):

  • Female

  • Non-smoker

  • Prior PONV

  • Anticipated post-op opioids → 4/4 = ~80% risk

  • Additional factors:

    • Laparoscopy → ↑ risk

    • BMI 32 → delayed gastric emptying

    • High anxiety → amplifies symptom perception and stress response

• Interaction Concerns:

  • Escitalopram + 5-HT3 antagonist = theoretical serotonin syndrome risk → extremely rare, but monitor post-op.

• Plan: Multimodal Prophylaxis (ANZCA PONV guideline):

  • Dexamethasone 8 mg IV after induction

  • Ondansetron 4 mg IV at the end (if no QT concerns)

  • Droperidol 0.625–1.25 mg IV intra-op (ECG pre-op in Scenarioville to check QT if combined with SSRI)

  • TIVA with propofol if feasible → preferred in high-risk patients

• Pain Management:

  • Non-opioid multimodal plan: IV paracetamol, NSAID

  • Consider low-dose ketamine infusion (Scenarioville lacks regional options)

Would you avoid ondansetron because of escitalopram?

No — the interaction is theoretical and very rare. I would use ondansetron for its proven antiemetic benefit, while monitoring for any signs of serotonin excess (e.g., agitation, rigidity, hyperreflexia).

Justification:

• Clinical risk << benefit.

• ANZCA guidelines support ondansetron in high-risk patients.

• Theoretical QT prolongation risk is minimal at standard doses.

How does the lack of regional techniques in Scenarioville affect your plan?

• maximize non-opioid analgesia (paracetamol, NSAID),

• consider intra-op ketamine 0.1–0.2 mg/kg/hr,

• avoid long-acting opioids.

Justification:

• Regional blocks (e.g., TAP) are effective but not available here.

• Need to achieve analgesia without increasing PONV risk.

• Ketamine reduces opioid requirement and is well tolerated at low doses.

What if she had no benefit from ondansetron previously?

• add cyclizine (if available),

• combine droperidol + dexamethasone intra-op.

Justification:

• Guidelines recommend using different class if one agent failed.

• Cyclizine is 3rd line but would be more comfortably used by anaesthetics in refractory PONV.

• Droperidol is effective even in patients who fail 5-HT3s.

How would you adjust this for a day case in Scenarioville?

• Ensure no PONV for at least 1 hour, tolerating fluids.

• Discharge only with adult escort, written antiemetic prescription, and clear return instructions.

• Provide ondansetron wafers or domperidone PRN, and arrange next-day GP or nurse review.

Justification:

• Day surgery safety depends on PONV control + follow-up access, especially with prior readmission history.

• Scenarioville has limited ED staffing after hours, so proactive planning essential.

The patient develops HR 38 during insufflation. How will you manage this?

• Immediate Steps:

  • Stop insufflation, reduce pressure to <12 mmHg.

  • Atropine 500 mcg IV as first-line treatment.

  • If HR remains low: Adrenaline 10 mcg boluses.

• Explain Cause:

  • Peritoneal stretch stimulates vagal afferents → bradycardia.

  • Occurs early during insufflation; sympathetic tone may dominate later (tachycardia, HTN).

• Other Physiologic Changes:

  • ↓ venous return → ↓ preload/CO

  • ↑ CO₂ absorption → hypercapnia

  • ↓ renal perfusion

  • In Trendelenburg: worsens preload and vagal tone

• Prevention:

  • Use gradual insufflation, lower pressure, and pre-op glycopyrrolate if high vagal risk.

Why does pneumoperitoneum cause bradycardia initially?

The peritoneal stretch reflex triggers vagal afferents, leading to parasympathetic dominance and bradycardia — especially during rapid insufflation.

Justification:

• Vagal reflex = early event.

• Sympathetic response follows later as CO₂ accumulates.

How does the lack of ICU in Scenarioville change your management?

• Early correction and prevention are critical.

• If bradycardia is prolonged or recurrent, escalate to retrieval team early.

• Ensure no progression to hypotension or LOC.

Justification:

• Scenarioville has no ICU or HDU, and retrieval takes 2 hours → must prevent deterioration before it begins.

• No telemetry beds beyond basic monitoring.

What monitoring is essential?

• ECG: track bradyarrhythmias

• Capnography: detect hypercapnia (CO₂ absorption)

• SpO₂: gas embolism or ventilation-perfusion mismatch

• NIBP and ETCO₂ trending also important.

Justification:

• Monitoring supports real-time diagnosis of cause (e.g., gas embolism = sudden ETCO₂ drop, hypoxia, hypotension).

Would you convert to open surgery?

Only if bradycardia is refractory or surgery cannot proceed safely laparoscopically despite pressure adjustments.

Justification:

• Conversion increases morbidity.

• Should be considered only after medical and technical optimisations fail.

Outline your extubation strategy and discharge criteria.

• Extubation Strategy:

  • Awake extubation with lidocaine 1 mg/kg IV to blunt coughing.

  • Avoid deep extubation in absence of reflux only if risk of retch/cough outweighs aspiration.

  • Ensure TOF >0.9, normal RR/TV, hemodynamic stability.

• Discharge Criteria (Day Surgery):

  • No PONV for at least 60 mins.

  • Oral fluids tolerated.

  • Stable vitals, ambulating.

  • Must have a responsible adult escort.

• Scenarioville-specific Plan:

  • No extended recovery unit → discharge only once fully criteria met.

  • Provide written antiemetic plan + contact numbers.

  • Early re-presentation plan to local ED or retrieval coordination if needed.

Would you use sugammadex given her BMI?

Yes — dose based on actual body weight. Sugammadex avoids neostigmine-related side effects (including bradycardia and PONV).

Justification:

• BMI 32 → risk of under-reversal if ideal weight used.

• Sugammadex = faster, more complete reversal.

What if no escort is available?

I would recommend overnight admission — given prior PONV admission, she's high risk for complications.

Justification:

• ANZCA Day Surgery policy: adult escort mandatory.

• Scenarioville ED is limited after hours → must plan for observation.

How would you manage PONV post-discharge?

• Prescribe oral ondansetron wafers or prochlorperazine.

• Provide retrieval service contact and written instructions.

• Recommend next-day GP review.

Justification:

• Anticipate recurrence.

• Patient is highly anxious → structured plan reassures and improves outcomes.

Why avoid opioids in recovery?

• Opioids are dose-dependent PONV triggers.

• Will prioritise paracetamol, NSAIDs, and non-opioid adjuncts (e.g., ketamine or clonidine).

Justification:

• History of severe PONV + Apfel 4/4 → avoid all avoidable triggers.

Key Phrases

• “Multimodal prophylaxis is essential — I’ll avoid opioids and use TIVA if feasible.”

• “Desufflation and atropine are first-line; this is vagally mediated.”

• “I’ll ensure TOF >0.9 and consider lidocaine to minimise emergence coughing.”

• “No escort = no discharge; overnight admission in Scenarioville is safer.”