2024.2 Day 1 VIVA 7

Regional Anaesthesia

A 50-year-old female comes to see you for a pre-anaesthetic assessment. She is booked for an open right inguinal hernia repair in a week's time. The hernia is clinically significant needing urgent surgical correction.

She is on no regular medications but has a 20-pack-year smoking history.

Her airway exam was unremarkable, apart from decreased air entry on all lung fields.

She is very keen to have her surgery at Scenarioville but has had an episode of awareness under GA with a previous procedure. She was encouraged by the referring surgeon to discuss with you the prospect of having her surgery done under a spinal block.

How would you assess her suitability for a spinal anaesthetic?

• History:

  • Surgical urgency mandates expedited, safe assessment.

  • Awareness under GA → psychological impact; anaesthetic technique choice crucial.

  • Smoking → likely underlying COPD; functional reserve must be assessed.

• Physical Exam:

  • Airway (anticipate possible GA conversion); assess ease of intubation.

  • Lungs: Reduced air entry suggests potential COPD — implications for oxygenation during sedation or conversion to GA.

  • Back: Palpation for deformities or infection.

• Investigations:

  • FBC, Coags (especially as no ROTEM available).

  • CXR if pulmonary status unclear (important rural decision without respiratory physicians).

• Contraindications:

  • Absolute: Refusal, sepsis, bleeding.

  • Relative: Coagulopathy, unstable cardiovascular status.

• Shared Decision-Making:

  • Essential for informed consent and respecting patient's prior GA experience.

What absolute contraindications would you specifically look for in this patient?

• Patient refusal: Ethical and medico-legal imperative; spinal cannot be forced.

• Infection (local/systemic): Risk of meningitis if spinal performed through infected tissues.

• Uncorrected coagulopathy: Risk of spinal epidural haematoma — catastrophic in a centre without neurosurgery (PS18 ANZCA).

• Severe hypovolaemia: Risk of exacerbated hypotension following sympathectomy.

• Raised ICP: Spinal could precipitate brain herniation.

Given her smoking history and decreased air entry, how would you further assess respiratory risk preoperatively?

• Bedside examination: Signs of respiratory effort (accessory muscle use) correlate with respiratory reserve.

• SpO₂ at rest and exertion: Hypoxia unmasked with minimal activity can predict perioperative decompensation.

• 6MWT (if feasible): Simple functional assessment validated even in resource-poor settings. (✏️Notes)

• Chest X-ray: To identify hyperinflation, bullae, or signs of underlying lung disease.

• Rationale: Planning for sedation or GA requires predicting oxygenation and ventilation adequacy.

If her INR was 1.6, would you proceed with spinal anaesthesia?

No.

• PS18 (ANZCA) and ESA guidelines: INR must be ≤1.4 for safe neuraxial block.

• INR 1.6 indicates elevated bleeding risk, and spinal haematoma consequences would be catastrophic in rural Scenarioville.

• Coagulopathy should be corrected first (vitamin K or FFP).

In a rural centre like Scenarioville, how does the lack of HDU/ICU impact your decision-making?

• Must favour low-risk patients for major procedures under regional techniques.

• Complications such as prolonged hypotension, respiratory failure post-GA are more dangerous without HDU monitoring.

• Early planning for retrieval if unexpected deterioration occurs.

What would you include in your consent discussion given her history of awareness?

• Acknowledge and validate her previous traumatic experience.

• Emphasize that spinal avoids the risks of awareness.

• Explain possibility of spinal failure (~1–3%), and potential need for sedation or conversion to GA (to preserve autonomy and trust).

• Standard risks: hypotension, nerve injury, PDPH must still be explained.

Imagine your spinal block is inadequate during surgery. How would you manage this situation in Scenarioville?

1. Immediate Assessment

• Check dermatomal spread:

  • Symmetry (both sides equal?)

  • Height (does block reach surgical dermatomes?)

  • Density (sharp/dull sensation preserved?) Justification: Objective sensory testing determines whether block is inadequate or partially effective; prevents unnecessary conversion.

• Assess severity:

  • Minor inadequacy: Localised incomplete block (e.g., small patchy area, mild discomfort).

  • Major inadequacy: Severe pain, extensive block failure.

• Pitfall:

  • Relying solely on patient's verbal complaints without formal dermatomal testing — underestimating or overestimating block.

2. Minor Block Inadequacy Management

• Sedation and analgesia supplementation:

  • Ketamine preferred: 0.25–0.5 mg/kg IV bolus → repeat as needed (e.g., 20–30 mg boluses).

    • Justification:

      • Preserves airway reflexes (essential rural safety feature).

      • Provides both analgesia and dissociative anaesthesia.

      • Maintains cardiovascular stability.

  • Alternative (careful) sedation: Propofol TCI or intermittent 10–20 mg boluses if minimal respiratory risk.

    • Titrate cautiously to maintain spontaneous ventilation.

• Supplemental oxygen:

  • 2–4 L/min via nasal prongs or Hudson mask.

• Monitoring:

  • Continuous end-tidal CO₂ if sedated to detect early hypoventilation.

• Pitfalls:

  • Over-sedation causing respiratory depression in a patient with underlying COPD.

  • Giving full anaesthetic doses instead of sedation doses.

3. Major Block Inadequacy Management

• Rapid Sequence Induction (RSI) GA Preparation:

  • Pre-oxygenate: 100% O₂ for 3–5 minutes. Justification: Rural setting → must maximise oxygenation before any airway manoeuvre.

• Induction Plan:

  • Induction agents:

    • Propofol 1–2 mg/kg IV (adjust lower for hypovolaemia or sedation already given).

    • Ketamine 1–2 mg/kg IV alternative if profound hypotension risk.

  • Muscle relaxant:

    • Rocuronium 1.0–1.2 mg/kg IV → provides rapid intubating conditions.

    • Backup: Succinylcholine 1–1.5 mg/kg IV if severe airway concern (but careful with COPD/hyperkalaemia).

• Airway Management:

  • Primary: Video laryngoscope ready (higher success in rural settings with difficult airway).

  • Secondary: LMA as rescue.

  • Tertiary: Cricothyrotomy kit ready (can’t intubate, can’t oxygenate scenario).

• Maintenance:

  • Short-acting volatile agent (sevoflurane or desflurane if available).

• Pitfalls:

  • Delaying decision to convert when signs clearly suggest block failure.

  • Inadequate preoxygenation before RSI.

  • Not having backup airway equipment immediately at hand.

4. Planning and Preparation

• Prepare airway and emergency equipment BEFORE attempting supplementation:

  • Video laryngoscope

  • LMA

  • Cricothyrotomy set

  • Difficult airway trolley Justification: Resources are limited — delays are riskier; no backup intensivist or anaesthetic consultant.

• Check IV access:

  • Ensure two reliable large-bore IVs in place.

• Prepare vasopressors:

  • Metaraminol 0.5–1 mg boluses or norepinephrine infusion if profound hypotension.

5. Communication

• Inform the surgeon:

  • Nature of block failure.

  • Options (sedation vs GA conversion).

  • Estimated time to secure alternative anaesthesia.

• Inform theatre team:

  • Ask scrub/scout nurses to prepare airway rescue equipment if not already.

• Documentation:

  • Clear record of block failure, decisions taken, and patient stability.

• Pitfall:

  • Not warning the surgical team early enough → sudden stop causes panic or miscommunication.

6. Rural Context Specific Adaptations (Scenarioville)

• Lower threshold to convert to GA early: Justification: Inadequate block + limited ICU backup = high-risk situation if allowed to deteriorate.

• Plan for post-op care:

  • Monitor in special care unit (cardiac monitored beds available, no HDU).

  • If prolonged ventilation needed → immediate retrieval referral.

• Consider sending early warning to retrieval service if anticipating complications.

• Pitfall:

  • Persisting too long with inadequate regional anaesthesia hoping it will "improve" — delays definitive management and worsens outcomes.

Step	Action	Dose (if applicable)	Rationale	Pitfalls
1	Assess dermatomal block	N/A	Objectively define adequacy	Assuming patient’s verbal feedback sufficient
2	Minor inadequacy → sedation	Ketamine 0.25–0.5 mg/kg	Analgesia with airway preservation	Oversedation, hypoventilation
3	Major inadequacy → RSI GA	Propofol 1–2 mg/kg; Rocuronium 1–1.2 mg/kg	Secure airway definitively	Inadequate preoxygenation, delayed conversion
4	Equipment prep	N/A	Avoid emergency surprises	No backup airway ready
5	Communicate with team	N/A	Shared understanding, safer conversion	Late communication causing panic
6	Rural escalation	N/A	Limited rescue options — early action essential	Hoping block improves when failing

What factors predict a high likelihood of spinal block failure?

• Patient factors: Obesity, scoliosis → difficulty achieving midline or adequate spread.

• Technical factors: Poor positioning, incomplete intrathecal drug delivery.

• Drug factors: Inadequate dose, wrong baricity or concentration affecting CSF spread.

• Understanding predictors allows pre-emptive identification of likely difficulties.

How would you safely supplement an inadequate block without proceeding to GA immediately?

• Ketamine: Maintains airway reflexes, provides analgesia without respiratory depression.

• Light sedation with propofol: Titrate to Ramsay Sedation Scale 2–3; avoid deep sedation in case of respiratory compromise.

• Oxygen and airway rescue equipment must be immediately ready.

If proceeding to GA, what specific anaesthetic considerations are important in this rural hospital?

• Anticipate difficult airway (due to smoking-related COPD changes).

• Apply RSI principles due to aspiration risk.

• Choose short-acting agents to allow rapid recovery (sevoflurane, desflurane).

• Maintain haemodynamic stability aggressively (rural setting limits advanced ICU support for hypotension/shock).

How would you involve the surgeon in troubleshooting an inadequate spinal intraoperatively?

• Shared planning: modify surgical approach if feasible (smaller incision, faster surgery).

• Ensure surgeon aware that delay for spinal supplementation or GA conversion may occur.

• Strong team communication essential to optimize patient outcomes.

What specific backup airway plans would you have given her risk factors?

• Primary: Videolaryngoscope (higher first-pass success).

• Secondary: Supraglottic airway device immediately ready.

• Tertiary: Scalpel cricothyroidotomy kit ready if “can’t intubate can’t oxygenate” (CICO).

• COPD and rural setting mandate low threshold for airway escalation.

How would you manage her VTE prophylaxis perioperatively in the context of a spinal anaesthetic?

1. VTE Prophylaxis Management

Mechanical Prophylaxis

• Start intraoperatively:

  • TED stockings (thigh-length) + intermittent pneumatic compression (IPC) devices immediately after anaesthetic induction or before surgery commences. Justification:

  • Smoking + surgery = moderate VTE risk even for day-case surgeries.

  • Mechanical prophylaxis is safe, effective, and carries no bleeding risk.

• Pitfall:

  • Forgetting to start mechanical prophylaxis early → avoidable early VTE formation.

Pharmacological Prophylaxis (LMWH)

• Timing:

  • Administer first dose 6–12 hours after surgery if:

    • Haemostasis achieved

    • No ongoing bleeding

    • Neurological status stable (no spinal cord compression signs)

• Drug and dose:

  • Enoxaparin 40 mg SC daily (standard prophylactic dose)

  • Adjust if low body weight or renal impairment (e.g., 20–30 mg daily).

• Critical Timing Rule (Per ANZCA PS18 / ESA Guidelines):

  • Minimum 4-hour interval after spinal needle removal before LMWH can be given.

  • Next spinal/epidural manipulation (if needed) delayed 10–12 hours after LMWH.

• Justification:

  • Early LMWH administration post-spinal increases the risk of epidural haematoma → a catastrophic complication in rural hospitals with no neurosurgical backup.

Contraindications to LMWH Initiation

• Active bleeding

• Coagulopathy

• Renal impairment (if severe, dose adjustment or alternative agent)

Pitfalls to Avoid

• Starting LMWH too early (before safe neuraxial window) → risk of spinal haematoma.

• Forgetting to check platelet count before LMWH if postoperative thrombocytopenia suspected.

How would you manage a severe post-dural puncture headache ( 📃 notes)

Initial Conservative Management

• Bed Rest:

  • Encourage supine positioning as tolerated.

• Hydration:

  • Oral or IV fluids to maintain CSF production.

• Caffeine therapy:

  • Oral caffeine 300 mg (coffee or tablets) or

  • IV caffeine citrate 500 mg over 2–4 hours if severe symptoms. Justification:

  • Caffeine promotes cerebral vasoconstriction and stimulates CSF production, reducing PDPH symptoms.

• Analgesia:

  • Regular paracetamol and NSAIDs (if no contraindication) for symptom relief.

• Monitoring:

  • Regular neurological checks — important to differentiate evolving serious complications (e.g., subdural haematoma).

None pf these treatments are fully successful, what considerations need be made for an epidural blood patch (EDP)?

Indications for Escalation to Epidural Blood Patch (EBP)

• If PDPH persists >48 hours despite conservative measures or

• Severe headache significantly affecting function (e.g., unable to mobilize, eat, or perform ADLs).

Epidural Blood Patch (EBP)

• Procedure:

  • 15–20 mL of autologous blood injected into epidural space at or near dural puncture level.

• Success Rate:

  • 85–90% symptom resolution after first blood patch.

• Repeat blood patch if necessary after 24 hours if symptoms persist.

Contraindications to EBP

• Systemic or local infection

• Coagulopathy

• Raised intracranial pressure

• Patient refusal

Risks of EBP

• Back pain

• Repeat dural puncture

• Epidural haematoma (rare but serious)

• Infection (epidural abscess, meningitis)

Rural Centre (Scenarioville) Specific Considerations

• Operator skill:

  • If no local anaesthetist skilled in EBP → early discussion with retrieval services or consider transfer.

• Post-EBP monitoring:

  • Patient to stay supine for 1–2 hours post-procedure.

  • Observations: neurology, vital signs, pain assessment.

• Pitfalls:

  • Performing EBP too early (before confirming persistent symptoms) → exposes patient to unnecessary risk.

  • Missing early signs of more serious complications (e.g., subdural haematoma).

What is the safe timing for LMWH administration around spinal or epidural procedures?

• First LMWH prophylactic dose minimum 4 hours post-procedure (ANZCA/ESA standards).

• Catheter (if used) should be removed 12h after last LMWH dose to minimize risk of epidural haematoma.

• Timing critical to prevent devastating haematoma complications.

How would you differentiate a PDPH from other causes of postoperative headache?

• Postural character: PDPH worse upright, better lying flat — classic distinguishing feature.

• Timing: Typically onset within 24–48h after dural puncture.

• Associated features: Neck stiffness, photophobia.

• Focal neurological signs absent → if present, investigate for more serious causes (e.g., CVT, SAH).

What are the contraindications to an epidural blood patch in this setting?

• Infection: Risk of seeding infection into CNS.

• Coagulopathy: Increased risk of epidural haematoma.

• Raised ICP: Injection could worsen herniation.

• Patient must be properly selected to avoid catastrophic complications.

If she had a dural puncture but minimal symptoms, would you proceed immediately to a blood patch?

• No. Conservative management first — most mild PDPH resolve without intervention.

• Blood patch carries risks (infection, new dural puncture, haematoma).

• Only escalate if significant impact on QoL or severe symptoms persist >48h.

Given Scenarioville’s resources, how would you escalate care if a complication occurred after an epidural blood patch?

• Early consultation with aeromedical retrieval team.

• Arrange urgent imaging (CT or MRI spine).

• Expedite transfer to tertiary centre with neurosurgery if epidural haematoma suspected.

• Early action critical to preserve neurological function.