Perioperative Medicine — Written Clinical Reasoning

SAQ 1 — Integrated Perioperative Assessment and Optimisation (25 marks, 35 minutes)

Prompt: Construct a problem list for this patient, perform a structured preoperative assessment covering cardiac risk, pulmonary optimisation, diabetes management, anticoagulation and antiplatelet strategy, chronic medication review, and VTE prophylaxis, and outline an integrated perioperative plan with justification for each decision. [1]

Model Answer

Problem list (4 marks): [1]

1. Cardiac risk stratification — Revised Cardiac Risk Index at least 3 (high-risk intra-abdominal surgery, ischaemic heart disease, insulin-treated diabetes; CKD adds risk), with poor functional capacity (fewer than 4 METs).
2. Perioperative diabetes — insulin-treated type 2 diabetes on an SGLT2 inhibitor, HbA1c 64 mmol/mol (target under 69 acceptable but could be improved), facing prolonged fasting.
3. Anticoagulation and antiplatelet strategy — apixaban for AF, dual antiplatelet therapy with a recent drug-eluting stent (8 months).
4. Chronic airways disease — COPD FEV1 55 per cent, active smoker.
5. Chronic medication review — perindopril, bisoprolol, inhaled therapy, insulin, empagliflozin.
6. VTE and infection risk — cancer surgery, obesity, immobility.
7. Renal impairment — CKD stage 3a (eGFR 45), affecting drug dosing. [1]

Cardiac risk assessment (4 marks): His RCRI is high — three or more points (high-risk surgery, ischaemic heart disease, insulin-treated diabetes), placing him in the roughly 5 to 6 per cent major cardiac complication category. His functional capacity is poor (he cannot climb a flight of stairs without breathlessness, i.e. fewer than 4 METs). By the guideline rule, a high-risk patient with poor functional capacity warrants functional cardiac testing (dobutamine stress echocardiography) if the result will change management — and in this case a positive test or induced ischaemia would prompt cardiology review and consideration of optimisation, though prophylactic coronary revascularisation purely to clear for surgery is not beneficial (CARP trial). He should continue his bisoprolol (do not stop; do not initiate a new beta-blocker acutely — POISE). Confirm he is on a statin (he is at high vascular risk; start one if not already prescribed). His recent stent is the dominant cardiac constraint (see below). [1]

Coronary stent and antiplatelet strategy (4 marks): His drug-eluting stent was inserted eight months ago, and he is on aspirin plus clopidogrel. The minimum stent period is six months (or three to six months in selected stable patients), so he is just past the conservative floor for elective surgery. The plan, agreed with cardiology: continue aspirin through the surgery (stent thrombosis is catastrophic, mortality 30 to 50 per cent), and stop the clopidogrel 5 days before surgery for major intra-abdominal cancer resection (moderate to high bleeding risk), restarting as soon as haemostasis is secure. Aspirin continuation is supported by the interpretation of POISE-2, which showed aspirin did not reduce events in unselected patients but the stent population is the recognised exception. The clopidogrel should be restarted postoperatively and the full intended 12-month dual antiplatelet course completed. [1]

Anticoagulation (apixaban) for AF (3 marks): Apixaban does not require bridging (rapid onset). Stop apixaban 48 hours before surgery (two missed doses) for this major intra-abdominal procedure, with attention to his renal function (eGFR 45 slightly prolongs clearance, but apixaban is only about 27 per cent renally cleared so 48 hours is adequate). Restart once haemostasis is secure, typically 24 to 72 hours after a major resection. His CHA2DS2-VASc is high (age, hypertension, diabetes, vascular disease), so anticoagulation must not be interrupted longer than necessary. [1]

Diabetes management (4 marks): Stop the empagliflozin 3 days before surgery — the danger is euglycaemic diabetic ketoacidosis precipitated by fasting, surgical stress, dehydration and the drug's mechanism, and it is frequently missed because the glucose may be only mildly elevated. On the day of surgery, place him first on the list. Continue his glargine (basal insulin) at 75 per cent of his usual dose on the night before and the morning of surgery, and omit the meal-time rapid-acting insulin while fasting. Because he faces a major resection with prolonged fasting and insulin-treated diabetes, start a variable-rate intravenous insulin infusion (VRIII) with a glucose-containing substrate fluid and hourly capillary glucose monitoring, targeting 6 to 10 mmol/L — the VRIII replaces the obsolete sliding scale. Resume his usual basal-bolus regimen once he is eating, overlapping the first subcutaneous dose with the infusion to prevent rebound hyperglycaemia, and restart the empagliflozin only when he is eating and drinking normally and clinically stable. [1]

Pulmonary optimisation (2 marks): Encourage smoking cessation now — even a short interval improves carbon monoxide clearance and ciliary function, and recent cessation does not increase risk. Optimise his COPD: confirm inhaler technique, escalate to appropriate GOLD therapy (he is on a LAMA and ICS-LABA; ensure correct use), check for and treat any active exacerbation, and teach incentive spirometry and deep-breathing exercises before admission. Plan for early mobilisation, adequate analgesia to permit coughing, and avoidance of nasogastric tubes where possible. Consider regional analgesia (epidural or transversus abdominis plane block) as part of an ERAS pathway. [1]

Chronic medication review (2 marks): Bisoprolol — continue. Perindopril — stop the morning dose for this major surgery (intra-operative hypotension risk), and restart once haemodynamically stable and renal function stable. Inhaled COPD therapy — continue on the morning of surgery. Add a statin if not already prescribed. Give stress-dose hydrocortisone only if he were on long-term steroids (he is not). Avoid NSAIDs in the perioperative period given his CKD and bleeding risk. [1]

VTE prophylaxis (2 marks): He is very high VTE risk by Caprini (active cancer, major abdominal surgery, age, obesity, immobility). Prescribe pharmacological prophylaxis with LMWH (enoxaparin 40 mg subcutaneously daily, dose-adjusted for eGFR 45 — enoxaparin 40 mg daily is acceptable down to CrCl 30) once haemostasis is secure, typically 6 to 12 hours postoperatively. Add mechanical prophylaxis (graduated compression stockings and intermittent pneumatic compression) during surgery and while in bed, after checking his arterial circulation. Continue prophylaxis for the full hospital stay and consider extended prophylaxis for 4 weeks given the cancer surgery. First LMWH dose is timed postoperatively after haemostasis to balance efficacy and bleeding. [1]

SAQ 2 — Perioperative Anticoagulation Reversal (10 marks, 15 minutes)

Prompt: A 69-year-old woman on warfarin for a mechanical mitral valve presents 48 hours after an emergency laparotomy for a perforated diverticulum with signs of intra-abdominal bleeding. Her warfarin was withheld perioperatively but her INR on admission was 7.4 and is now 3.8. She is haemodynamically unstable. Outline the immediate and subsequent anticoagulation management, explaining the pharmacology of each agent. [1]

Model Answer

Immediate priority (3 marks): Resuscitate with ABCDE — large-bore intravenous access, crossmatch, fluid and blood product resuscitation, and call the surgical and haematology teams. The bleeding is surgical and likely needs source control (re-laparotomy), but the coagulopathy must be corrected in parallel so that any intervention is not defeated by ongoing anticoagulation. [1]

Reversal of the warfarin effect (4 marks): Give 4-factor prothrombin complex concentrate (4F-PCC) plus intravenous vitamin K 10 milligrams. The pharmacology is the key: warfarin inhibits vitamin-K-dependent synthesis of factors II, VII, IX and X. PCC is a concentrate of these four factors (plus proteins C and S) and so restores haemostasis within minutes by directly replacing the missing factors; vitamin K is the cofactor for hepatic carboxylation of these factors and takes 6 to 12 hours to enable new synthesis, so it sustains but does not acutely achieve reversal. Sarode and colleagues showed 4F-PCC was non-inferior to plasma for haemostasis and superior for rapid INR correction, with a smaller volume avoiding circulatory overload. Fresh frozen plasma is an inferior alternative because it requires a larger volume, takes longer, and carries transfusion and volume risks. Vitamin K alone is dangerously too slow for active bleeding. [1]

Subsequent anticoagulation (3 marks): Once the bleeding is controlled and the patient is stable, anticoagulation must be reintroduced carefully because the mechanical mitral valve is the highest annual thrombotic risk of any indication. Restart warfarin as soon as haemostasis is secure, and bridge with therapeutic-dose LMWH (for example enoxaparin 1 milligram per kilogram twice daily) beginning 24 to 48 hours postoperatively once surgical bleeding has settled, continuing LMWH until the INR is again in the therapeutic range (2.5 to 3.5 for a mechanical mitral valve). The vitamin K given for reversal means the INR will take several days to rise again on warfarin, so bridging is essential. The decision is a careful balance — too early and the bleeding recurs, too late and the valve thromboses — and is made jointly by surgery, haematology and cardiology, with daily reassessment of the bleeding-thrombosis trade-off. [1]