Perioperative Hypothermia and Myocardial Injury After Non-cardiac Surgery

Hypothermia increases sympathetic activation, promotes tachycardia, and causes hypertension —
all of which may increase the risk of myocardial injury. Moderate perioperative hypothermia
is now uncommon, but mild hyperthermia (≈35.5°C) remains common. Whether aggressive warming
to a truly normothermic level (≈37°C) improves outcomes remains unknown.

Inclusion Criteria:

- Scheduled for major noncardiac surgery expected to last 2-6 hours;

- Having general anesthesia;

- Expected to require at least overnight hospitalization;

- Expected to have >50% of the anterior skin surface available for warming;

- Have at least one of the following risk factors:

a. Age over 65 years; b. History of peripheral vascular surgery; c. History of
coronary artery disease; d. History of stroke or transient ischemic attack; e. Serum
creatinine >175 µmal/L (>2.0 mg/dl); f. Diabetes requiring medication; e. Hypertension
requiring medication; g. Current smoking.

Exclusion Criteria:

- Have a clinically important coagulopathy in the judgement of the attending
anesthesiologist;

- Are septic (clinical diagnosis by the attending anesthesiologist);

- Body mass index exceeding 30 kg/m2;

- End-stage renal disease requiring dialysis;

- Surgeon believes patient to be at particular infection risk.