A 72-year-old man with COPD and ischaemic heart disease is being considered for an open abdominal aortic aneurysm repair. He completes cardiopulmonary exercise testing (CPET): anaerobic threshold 9.8 mL/kg/min, peak VO₂ 14 mL/kg/min, with no ischaemic ECG changes during testing. The surgical team discusses how these results should influence his perioperative plan. Which interpretation and action are most appropriate?
- AThe results are normal for a man of his age with COPD, so he can be listed as a routine case
- BCPET results have no established bearing on surgical planning
- CHe must be refused open surgery outright on these numbers alone
- DA low anaerobic threshold marks him as high risk: it informs the shared decision, triggers prehabilitation and planned critical care admission
- EThe test should simply be repeated after a fortnight of rest, and repeated again as needed until a more representative result is finally obtained
Show answer and explanation
Correct answer: D
CPET measures the integrated performance of the heart, lungs and circulation under stress, and the anaerobic threshold — the oxygen uptake at which anaerobic metabolism supplements aerobic delivery — is its most used perioperative marker. A threshold below about 10 to 11 mL/kg/min identifies patients at substantially increased risk of cardiorespiratory complications and death after major surgery, effectively quantifying the physiological reserve available to weather the post-operative systemic inflammatory demand. The result is used constructively, not punitively: it sharpens the shared decision-making conversation (open repair versus endovascular options versus surveillance), directs prehabilitation (structured exercise, smoking cessation, anaemia and medical optimisation), and mandates planning — high-risk patients are booked for critical care rather than discovered to need it.
Why the others are wrong: A — an anaerobic threshold under 10 with a peak VO₂ of 14 is distinctly abnormal; major aortic surgery on this physiology as a day case is nonsensical. B — objective risk assessment exists precisely to change planning; ignoring it wastes the test. C — CPET stratifies risk to inform choice; it is not an automatic veto, and EVAR or conservative strategies may serve him better. E — repeating a valid test seeking a different answer misunderstands its purpose, though re-testing after genuine prehabilitation gains is legitimate.
Key point: An anaerobic threshold below about 10–11 mL/kg/min on CPET marks high perioperative risk — used to guide shared decisions, prehabilitation and planned critical care admission, not to deny surgery reflexively.
Guidelines: POETTS consensus recommendations and CPOC guidance on cardiopulmonary exercise testing: an anaerobic threshold below about 11 mL/kg/min identifies high perioperative risk — shared decision-making, prehabilitation and planned postoperative critical care.