2024.2 Day 2 VIVA 18

General Anaesthesia and Sedation

An 80-year-old man is on your list for an elective Transurethral Resection of the Prostate (TURP). You see him in your clinic 2 weeks before his planned surgery.

His medical history includes hypertension, transient ischemic attack (TIA), type 2 diabetes mellitus, and stage 3 chronic kidney disease.

His current medications are rivaroxaban, candesartan, atorvastatin, and metformin. He has no known allergies and is living independently with some assistance from his daughter.

Please outline your pre-operative assessment.

In addition to my normal pre-operative assessment I would focus on:

Cardiovascular:

  • TIA history: timing (<3 months = increased risk), residual symptoms, assess antithrombotic plan.

  • BP control: monitor for periop hypotension, hold candesartan on DOS.

  • Functional status: estimate METs (e.g. walking up stairs, housework).

Renal/Diabetes:

  • CKD3 (eGFR 30–60): adjust medications, avoid NSAIDs, monitor electrolytes and fluid balance.

  • Metformin: hold 48h pre-op due to lactic acidosis risk especially if contrast used.

Anticoagulation:

  • Rivaroxaban: with CrCl 30–50, stop 48h pre-op; extend to 72h if CrCl <30.

  • Low thromboembolic risk (CHA2DS2-VASc = 4, no recent stroke), bridging not required.

Geriatric Risks:

  • Frailty screening (e.g., SARC-F, gait speed).

  • Baseline cognition: Mini-Cog or 4AT to assess risk of post-op delirium.

Scenarioville Context:

  • No access to neuro/ICU: document detailed neuro exam pre-op.

  • Limited blood bank: ensure G&S pre-op; crossmatch if bleeding risk high.

Would you request an echocardiogram?

  • Not routinely unless there are clinical signs of HF or murmur suggestive of AS.

  • Echo not readily available in Scenarioville; may delay surgery.

  • Functional capacity and clinical exam are primary tools here.

How would you modify if his CrCl was 25ml/min?

  • Extend rivaroxaban withholding to 72h pre-op to reduce bleeding risk.

  • Consider pre-op urinary catheter insertion for fluid monitoring.

  • Adjust other renally-excreted medications and avoid nephrotoxins periop.

His daughter mentions he’s been confused lately. Your action?

  • Delay surgery to allow formal cognitive assessment.

  • Investigate for reversible causes (infection, metabolic derangement).

  • Optimise and document baseline cognition to differentiate from post-op delirium.

The surgeon insists on continuing metformin. Your response?

  • Explain that continuing metformin increases risk of lactic acidosis in setting of impaired renal function or periop hypotension.

  • Refer to ANZCA PS56 guidelines: metformin should be withheld 48h pre-op and only resumed once renal function is stable.

Your spinal fails. Outline your GA plan for TURP in this patient.

Airway Plan:

  • RSI using ketamine 1mg/kg and rocuronium (avoid propofol-induced hypotension).

  • ETT preferred over LMA: allows secure airway during prolonged lithotomy and irrigation.

Anaesthesia Maintenance:

  • Volatile agent: sevoflurane (desflurane not available); avoid high-dose opioids.

  • Consider BIS monitoring to prevent over-sedation.

TURP-Specific Risks:

  • Glycine absorption: limit resection time to <60 minutes; monitor Na+ intra-op.

  • Bleeding: ensure adequate surgical haemostasis; TXA 1g IV intra-op if needed.

Monitoring:

  • Basic: ECG, SpO₂, NIBP, ETCO₂.

  • Additional: consider arterial line if haemodynamic instability or labile BP.

The surgeon reports ‘poor visibility’ due to bleeding. Your management?

  • Reassess coagulation status: check INR/APTT.

  • Administer TXA 1g IV if not already given.

  • Catheter traction and bladder irrigation to manage local bleeding.

  • Discuss need for surgical hemostasis.

ETCO₂ suddenly drops to 15mmHg. Differential?

  • Acute drop suggests:

    • Venous gas embolism (from open venous sinuses in TURP).

    • PE (AF history, immobile elderly).

    • Circuit disconnection or massive blood loss.

  • Assess patient: SpO₂, ECG, capnograph waveform, volume status.

  • Stop surgery if required, give 100% FiO₂, consider central line and vasopressors.

How would you dose rocuronium with his CKD3?

  • Use reduced dose: 0.6mg/kg ideal body weight.

  • TOF monitoring mandatory for safe redosing.

  • Expect delayed clearance; avoid repeated doses unless necessary.

Post-op, he’s agitated and trying to remove his catheter. How will you manage this?

Differentials:

  • Hyperactive delirium (most likely).

  • Glycine toxicity (hyponatraemia <125 mmol/L).

  • Catheter discomfort or urinary retention despite catheter.

  • Hypoxia or pain.

Assessment and Management:

  • Reassure and reorient the patient; check hearing aids/glasses are in place.

  • Confirm catheter patency and bladder volume (bladder scan if possible).

  • Check serum Na+, glucose, ABG.

  • If delirium likely: haloperidol 0.5mg IV; avoid benzos.

  • Maintain quiet, well-lit room and family presence.

Scenarioville Issues:

  • No geriatrics → ensure discharge summary includes cognition concerns.

  • Limited staffing → nurse near desk or visible area.

His Na+ is 118mmol/L. Management?

  • Hypertonic saline 3% 100mL over 20 min under monitoring.

  • Restrict free water, avoid hypotonic fluids.

  • Repeat sodium in 1 hour; monitor for osmotic demyelination.

The nurse asks if this is dementia. How do you respond?

  • Delirium is acute and fluctuating; dementia is chronic and progressive.

  • Delirium more likely in the immediate post-op period.

  • Reassess cognition when patient is medically optimised.

When can he restart rivaroxaban?

  • Restart at 24h if haemostasis confirmed.

  • Delay to 48–72h if bleeding risk high.

  • Ensure safe oral intake and renal function prior to restart.

His daughter demands discharge. Your criteria?

  • Alert, oriented, mobilising independently or with supports.

  • Pain controlled on oral meds.

  • No signs of active bleeding.

  • Responsible adult at home for 24h observation.

Key Concepts Covered

  1. Pre-op risk balancing: anticoagulation, cognition, CKD.

  2. GA adaptation for elderly TURP: haemodynamic goals, TURP syndrome.

  3. Delirium: risk identification, non-pharm first, safety.

  4. Scenarioville constraints: no ICU, limited access to diagnostics.

  5. Post-op decision-making: discharge planning, rivaroxaban timing.

Critical Phrases:

  • "CHA2DS2-VASc=4 doesn’t justify bridging therapy."

  • "Glycine toxicity requires hypertonic saline if Na+ <125mmol/L."

  • "We must differentiate delirium from dementia post-operatively."

  • "Document baseline cognition clearly in the absence of geriatrics."

  • "Avoid over-sedation in elderly; use lowest effective haloperidol dose."

Pitfalls:

  • Restarting metformin too early post-op.

  • Delaying anticoagulant restart unnecessarily.

  • Assuming confusion is dementia without investigation.

  • Under-monitoring fluid shifts in TURP.

Scenarioville-Specific Risks:

  • No ICU/neurology → early escalation critical.

  • Limited diagnostics → lean on clinical exam, early retrieval if deterioration.

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