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

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.

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.

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).

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.