A Randomized Trial of a Supplemental Alarm for Critically Low Systolic Blood Pressure

Abstract

Background: Intraoperative hypotension is associated with complications that might be ameliorated by earlier intervention. We therefore tested the primary hypothesis that a supplemental decision support alert for critically low systolic blood pressure (SBP) decreases the duration of intraoperative hypotension.

Methods: We enrolled adults having surgery and anesthetized by attending anesthesiologists or nurse anesthetists under attending supervision. When invasive SBP <80 mmHg was detected for 3 consecutive minutes or any oscillometric SBP <80 mmHg, patients were randomly assigned to routine management or a visual alert and pager notification. Clinicians who received alerts were free to act on the alert or not. The primary outcome was time to return to SBP ≥ 80 mmHg. Secondary outcomes were time until SBP remained ≥ 80 mmHg for at least 10 minutes and the duration of hospitalization.

Results: One thousand five hundred ninety-eight patients were randomly assigned to the hypotension alerts and 1567 to no alerts. Randomized groups did not differ on time to return to SBP ≥ 80 mmHg after the first alert, with estimated adjusted hazard ratio of 0.99 (95% confidence interval, 0.92-1.06; P = 0.69). The median time [quartiles] to return to SBP ≥ 80 mmHg was 1 [0, 3] minutes in each group and 1 [0, 3] minutes in the nonalert group (P = 0.69). Hospital length of stay was also similar, with the median [quartiles] lengths of stay being 2 [1, 4] days in the alert group and 2 [1,5] in the nonalert group (P = 0.35).

Conclusions: An additional warning for severe hypotension did not reduce the duration of hypotension or hospitalization. Decision support alerts may be more useful for more complicated situations.