2024.2 Day 1 VIVA 6

Peri-operative Medicine

You are assessing a 70-year-old female patient who presents to the preadmission clinic for an elective right total hip replacement due to osteoarthritis.

She has Type 2 Diabetes and Ischemic Heart Disease (IHD), having had a drug-eluting stent placed four months ago. She has no allergies, and her BMI is 31.1.

Medications:

• Dapagliflozin

• Metformin

• Clopidogrel

• Aspirin

• Atorvastatin

• Atenolol

How do you assess the severity and stability of her diabetes and ischaemic heart disease?

Diabetes Assessment:

• Glycaemic control:

  • Recent HbA1c result → goal <8% for safe surgery.

  • Recent hypoglycaemia episodes or wide glycaemic swings.

• Complications screen:

  • Diabetic nephropathy (U&E, albuminuria).

  • Autonomic neuropathy (postural hypotension, resting tachycardia).

• Perioperative medication adjustments:

  • SGLT2 inhibitor (Dapagliflozin) stopped at least 3 days pre-op (risk of euglycaemic DKA — ANZCA PG07(A)).

  • Metformin: hold morning of surgery to avoid lactic acidosis risk (especially if renal impairment).

  • Blood glucose monitoring every 2 hours intraop/postop.

IHD Assessment:

• DES placement 4 months ago:

  • High risk of stent thrombosis if dual antiplatelet therapy (DAPT) interrupted.

• Functional capacity (METs):

  • Ability to walk >4 METs (e.g., climb stairs without chest pain)?

• Symptom review:

  • New angina, dyspnea, orthopnea → may indicate unstable IHD.

• Investigations:

  • Recent ECG (ischemia), echo (LVEF), troponins if any symptoms.

• Perioperative medication considerations:

  • Continue aspirin throughout.

  • Discuss clopidogrel perioperative management with cardiology.

Scenarioville Specific Adaptation:

• No PCI service onsite.

• Need for robust risk stratification: Can this surgery proceed safely here?

Her HbA1c is 9.2% — how does this alter your surgical plan?

• Elective case should be postponed.

• Involve endocrinology for glycaemic optimisation → possibly insulin initiation or basal-bolus regimen.

• HbA1c >8.5–9% correlates with increased infection risk, poor wound healing, and prolonged hospitalisation.

• Risk of perioperative hyperosmolar states (e.g., HHS).

• Only proceed urgently if truly life/limb threatening.

Justification:

• Proceeding with poorly controlled diabetes violates standard perioperative safety (ANZCA guidelines)

How would you manage her if she reports chest tightness walking to the shops?

• Treat as unstable angina until proven otherwise.

• Delay surgery.

• Arrange urgent cardiology input.

• Investigate with non-invasive testing (e.g., dobutamine stress echo) or coronary angiography.

• Only proceed after confirming cardiac stability.

Justification:

• New ischemic symptoms = absolute contraindication to elective non-cardiac surgery.

How would you assess her frailty status?

• Clinical Frailty Scale (CFS): bedside tool assessing mobility, energy, and independence.

• Gait speed test: <0.8 m/s indicates frailty.

• Nutrition assessment: serum albumin, weight loss history.

• Activities of daily living (ADLs): any dependence suggests frailty.

Justification:

• Frailty predicts longer hospital stay, higher complication risk, poorer rehabilitation outcomes.

How would you decide whether Scenarioville is appropriate for her surgery?

• If evidence of active ischemia → not appropriate: transfer to tertiary centre.

• If stable angina, good METs, no new symptoms → surgery can proceed with caution.

• Must ensure plans are in place for early retrieval if postoperative cardiac event occurs.

Justification:

• Matching patient risk to hospital capability is critical to safe outcomes.

What would your plan be for managing her antiplatelet therapy preoperatively?

• Continue aspirin perioperatively.

• Aim to continue clopidogrel if possible, especially within 6 months of DES.

• If very high bleeding risk from surgery → cardiology consultation mandatory.

• No independent cessation of DAPT without specialist advice.

Justification:

• Stopping DAPT prematurely after DES risks catastrophic in-stent thrombosis.

She develops narrow-complex tachycardia at 180 bpm with hypotension (80/40) after induction. How would you manage this?

Immediate Management:

• Call for senior help immediately.

• Attach defibrillator pads.

• Administer 100% oxygen, confirm good IV access.

• Rapid ABCDE reassessment.

Identify Rhythm Stability:

• Narrow-complex SVT, hypotensive = unstable tachyarrhythmia.

Treatment:

• Immediate synchronized DC cardioversion (50–100J biphasic).

• Sedate lightly if time allows.

If Stable Post-Cardioversion:

• Investigate cause:

  • Hypoxia, hypovolemia, light anaesthesia.

  • Ischemia triggering arrhythmia?

Abort Surgery:

• Do not proceed with elective case after major intraoperative cardiac event.

If adenosine was attempted and failed, how would you escalate management?

• Unstable patient = direct synchronized cardioversion.

• Adenosine is inappropriate once hypotension established.

• If arrhythmia persists after initial shock:

  • Re-shock with increased energy.

  • Prepare for amiodarone loading (5 mg/kg IV over 30 mins) if necessary.

Justification:

• Electrical instability requires prompt electrical therapy, not delayed chemical attempts.

How would her history of reduced LVEF (35%) impact your intraoperative management?

• Avoid beta-blockers (risk of profound hypotension and worsening cardiac failure).

• Prioritise early cardioversion rather than pharmacological slowing.

• Post-event: initiate low-dose inotrope if necessary (e.g., noradrenaline, dobutamine cautiously).

Justification:

• Reduced EF → fragile myocardium; small perturbations can lead to shock.

If her blood pressure remains low after cardioversion, how would you investigate and manage this?

Differentials:

• Myocardial infarction (stunned myocardium).

• Hypovolemia (anaesthetic effect).

• Ongoing arrhythmia (e.g., AF with RVR).

Immediate actions:

• Repeat ECG, troponin.

• Fluid bolus judiciously (250 mL aliquots).

• Start noradrenaline infusion if persistent hypotension.

Justification:

• Stabilise haemodynamics before investigating further; minimize ongoing cardiac injury.

If she stabilises post-cardioversion, would you proceed with the operation?

• No.

• Elective surgery must be abandoned.

• Full cardiac workup is mandatory before any future anaesthetic.

Justification:

• Continuing after significant intraoperative cardiac event is unsafe.

How would you formally document this intraoperative event?

• Exact timeline of arrhythmia onset, vitals, treatments (adenosine, cardioversion).

• ECG strips attached if available.

• Drugs administered, dose, timing.

• Senior involvement recorded.

• Planned postoperative investigations and handovers noted.

Justification:

• Clear, defensible documentation is essential for safe handover and medico-legal reasons.

She is stable post-event but now has new T-wave inversions on ECG. How would you manage this?

Immediate Post-Op Plan:

• Treat as possible NSTEMI until ruled out.

• Serial troponins (0h, 3h, 6h).

• Repeat ECGs.

Further Management:

• If troponin elevated → urgent cardiology review.

• Arrange urgent retrieval to tertiary PCI centre.

Medication Management:

• Continue aspirin.

• Initiate therapeutic anticoagulation if NSTEMI confirmed.

Disposition:

• HDU level care until transfer.

• Monitor closely for arrhythmias, hemodynamic instability.

How would you diagnose and manage a postoperative NSTEMI?

Diagnosis more complex:

• Symptoms (masked by sedation/analgesia).

• Utilise serial ECG changes (dynamic TWI, ST depression).

• Troponin rise/fall.

Management:

• Dual antiplatelet therapy (aspirin + ticagrelor).

• Therapeutic anticoagulation (heparin infusion).

• Transfer to tertiary PCI facility urgently.

Justification:

• Early revascularisation reduces infarct size and mortality.

How would you arrange safe interhospital transfer for PCI?

• Retrieval service activation.

• Portable monitor and defibrillator in ambulance.

• Oxygen, dual antiplatelet loading if safe.

• Ongoing heparin infusion with dosing chart.

Justification:

• Optimise stability before and during transfer.

How would you explain the surgical cancellation to the patient and family?

• Honest, empathetic communication:

  • “We found a serious heart issue that must be treated urgently. Once your heart is stable and strong, we can safely reschedule your surgery.”

Justification:

• Building trust requires clear, compassionate explanation.

What are causes of postoperative hypoglycaemia and how would you prevent it?

• Reduced oral intake.

• Increased insulin sensitivity post-stress.

• Inappropriate continuation of oral hypoglycaemics.

Prevention:

• Frequent blood glucose monitoring.

• Adjust insulin/oral agents accordingly.

• Early nutrition support if needed.

What structured format would you use to handover to the retrieval team?

ISBAR:

• Identification: Name, age, comorbidities.

• Situation: NSTEMI post-SVT intraop.

• Background: Recent DES, high-risk cardiac profile.

• Assessment: ECG and troponin changes.

• Recommendation: Urgent PCI.

Of course — here’s a clean and targeted summary:

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Key Learning Points

1. Uncontrolled Diabetes (HbA1c >9%) = Delay Elective Surgery

   • Poor glycaemic control increases surgical site infections, delayed healing, and cardiac events.

   • Optimisation with endocrinology referral is essential before proceeding.

2. Recent DES (<6 months) = High Stent Thrombosis Risk

   • Dual antiplatelet therapy (DAPT) (aspirin + clopidogrel) should continue unless cardiology advises otherwise.

   • Bleeding risk must be accepted in favour of avoiding catastrophic MI.

3. Unstable Angina Symptoms = Absolute Surgical Contraindication

   • New chest pain or dyspnea demands urgent cardiac workup — elective surgery must be postponed.

4. Frailty Strongly Predicts Postoperative Outcomes

   • Gait speed, Clinical Frailty Scale, and nutritional status are practical bedside tools to assess surgical risk.

5. Intraoperative Unstable SVT Requires Immediate Cardioversion

   • Hypotension + tachyarrhythmia mandates synchronised DC cardioversion without delay.

6. Post-Event Hypotension Needs Structured Assessment

   • Differentiate between stunned myocardium, ischemia, hypovolemia, and anaesthetic causes.

   • Noradrenaline is the preferred first-line vasopressor.

7. New T-Wave Inversions Post-Op = Possible NSTEMI

   • Dynamic ECG changes + troponin rise = urgent cardiology input and transfer for PCI.

8. Structured Documentation and Handover are Critical

   • Full timeline, interventions, ECGs, troponins, and clear SBAR handover to retrieval team.

️Key Phrases

• "HbA1c >9% mandates deferral of elective surgery until glycaemic control is achieved."

• "Dual antiplatelet therapy must continue unless cardiology explicitly advises otherwise."

• "Unstable SVT requires immediate synchronized cardioversion — no pharmacologic delays."

• "Elective surgery must be abandoned after a major intraoperative cardiac event."

• "New T-wave inversions demand serial troponins to rule out NSTEMI."

• "Interhospital transfer for PCI must involve early heparinisation and cardiac monitoring during retrieval."