Background The effect of ambient temperature, with and without active warming, on intraoperative core temperature remains poorly characterized. The authors determined the effect of ambient temperature on core temperature changes with and without forced-air warming. Methods In this unblinded three-by-two factorial trial, 292 adults were randomized to ambient temperatures 19°, 21°, or 23°C, and to passive insulation or forced-air warming. The primary outcome was core temperature change between 1 and 3 h after induction. Linear mixed-effects models assessed the effects of ambient temperature, warming method, and their interaction. Results A 1°C increase in ambient temperature attenuated the negative slope of core temperature change 1 to 3 h after anesthesia induction by 0.03 (98.3% CI, 0.01 to 0.06) °C core /(h . °C ambient ) ( P < 0.001), for patients who received passive insulation, but not for those warmed with forced-air (–0.01 [98.3% CI, –0.03 to 0.01] °C core /[h . °C ambient ]; P = 0.40). Final core temperature at the end of surgery increased 0.13°C (98.3% CI, 0.07 to 0.20; P < 0.01) per degree increase in ambient temperature with passive insulation, but was unaffected by ambient temperature during forced-air warming (0.02 [98.3% CI, –0.04 to 0.09] °C core /°C ambient ; P = 0.40). After an average of 3.4 h of surgery, core temperature was 36.3° ± 0.5°C in each of the forced-air groups, and ranged from 35.6° to 36.1°C in passively insulated patients. Conclusions Ambient intraoperative temperature has a negligible effect on core temperature when patients are warmed with forced air. The effect is larger when patients are passively insulated, but the magnitude remains small. Ambient temperature can thus be set to comfortable levels for staff in patients who are actively warmed.

Background The relative contributions of intraoperative and postoperative hypotension to perioperative morbidity remain unclear. We determined the association between hypotension and a composite of 30-day myocardial infarction and death over three periods: (1) intraoperative, (2) remaining day of surgery, and (3) during the initial four postoperative days. Methods This was a substudy of POISE-2, a 10,010-patient factorial-randomized trial of aspirin and clonidine for prevention of myocardial infarction. Clinically important hypotension was defined as systolic blood pressure less than 90 mmHg requiring treatment. Minutes of hypotension was the exposure variable intraoperatively and for the remaining day of surgery, whereas hypotension status was treated as binary variable for postoperative days 1 to 4. We estimated the average relative effect of hypotension across components of the composite using a distinct effect generalized estimating model, adjusting for hypotension during earlier periods. Results Among 9,765 patients, 42% experienced hypotension, 590 (6.0%) had an infarction, and 116 (1.2%) died within 30 days of surgery. Intraoperatively, the estimated average relative effect across myocardial infarction and mortality was 1.08 (98.3% CI, 1.03, 1.12; P < 0.001) per 10-min increase in hypotension duration. For the remaining day of surgery, the odds ratio was 1.03 (98.3% CI, 1.01, 1.05; P < 0.001) per 10-min increase in hypotension duration. The average relative effect odds ratio was 2.83 (98.3% CI, 1.26, 6.35; P = 0.002) in patients with hypotension during the subsequent four days of hospitalization. Conclusions Clinically important hypotension—a potentially modifiable exposure—was significantly associated with a composite of myocardial infarction and death during each of three perioperative periods, even after adjustment for previous hypotension.

Background Whether patients on testosterone replacement therapy undergoing noncardiac surgery have an increased risk of postoperative in-hospital mortality and cardiovascular events remains unknown. We therefore sought to identify the impact of testosterone replacement on the incidence of a composite of postoperative in-hospital mortality and cardiovascular events in men undergoing noncardiac surgery. Methods Data from male American Society of Anesthesiologists I through IV patients 40 yr or older who underwent noncardiac surgery between May 2005 and December 2015 at the Cleveland Clinic (Cleveland, Ohio) main campus were included. The primary exposure was preoperative testosterone use. The primary outcome was a composite of postoperative in-hospital mortality and cardiovascular events. We compared patients who received testosterone and those who did not using propensity score matching within surgical procedure matches. Results Among 49,273 patients who met inclusion and exclusion criteria, 947 patients on testosterone were matched to 4,598 nontestosterone patients. The incidence of in-hospital mortality was 1.3% in the testosterone group and 1.1% in the nontestosterone group, giving an odds ratio of 1.17 (99% CI, 0.51 to 2.68; P = 0.63). The incidence of myocardial infarction was 0.2% in the testosterone group and 0.6% in the nontestosterone group (odds ratio = 0.34; 99% CI, 0.05 to 2.28; P = 0.15). Similarly, no significant difference was found in stroke (testosterone vs. nontestosterone: 2.0% vs . 2.1%), pulmonary embolism (0.5% vs . 0.7%), or deep venous thrombosis (2.0% vs . 1.7%). Conclusions Preoperative testosterone is not associated with an increased incidence of a composite of postoperative in-hospital mortality and cardiovascular events.