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:

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."

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