Perioperative Hypothermia and Myocardial Injury After Non-cardiac Surgery

Perioperative Hypothermia and Myocardial Injury After Non-cardiac Surgery

We propose to test the hypothesis that aggressive warming reduces the incidence of major cardiovascular complications, compared to routine care. Half of the participants will be randomly assigned to routine care (core temperature ≈35.5°C), while the other half will receive aggressive warming (>37°C core temperature) in a multi-center trial.

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.