Clinical question: What blood pressure deviations during surgery are predictive of mortality?
Background: Despite the widely assumed importance of blood pressure (BP) management on postoperative outcomes, there are no accepted thresholds requiring intervention.
Study design: Retrospective cohort.
Setting: Six Veterans’ Affairs hospitals, 2001-2008.
Synopsis: Intraoperative BP data from 18,756 patients undergoing major noncardiac surgery were linked with procedure, patient-related risk factors, and 30-day mortality data from the VA Surgical Quality Improvement Program database. Overall 30-day mortality was 1.8%. Using three different methods for defining hyper- or hypotension (based on standard deviations from the mean in this population, absolute thresholds suggested by medical literature, or by changes from baseline BP), no measure of hypertension predicted mortality; however, after adjusting for 10 preoperative patient-related risk factors, extremely low BP for five minutes or more (whether defined as systolic BP <70 mmHg, mean arterial pressure <49 mmHg, or diastolic BP <30 mmHg) was associated with 30-day mortality, with statistically significant odds ratios in the 2.4-3.2 range.
Because this is an observational study, no causal relationship can be established from these data. Low BPs could be markers for sicker patients with increased mortality, despite researchers’ efforts to adjust for known preoperative risks.
Bottom line: Intraoperative hypotension lasting five minutes or more, but not intraoperative hypertension, predicts 30-day mortality.
Citation: Monk TG, Bronsert MR, Henderson WG, et al. Association between intraoperative hypotension and hypertension and 30-day postoperative mortality in noncardiac surgery. Anesthesiology. 2015;123(2):307-319.
