Mean Arterial Pressure During the First 24 Hours After Cardiac Surgery and Acute Kidney Injury: An Observational...

Mean arterial pressure (MAP) after cardiac surgery may contribute to acute kidney injury (AKI). The authors sought to identify threshold MAP values during the first 24 hours postoperatively below or above which the risk of AKI increased.

Retrospective cohort study.

Single academic medical center.

One thousand three hundred sixty-eight adult patients undergoing cardiac surgery from October 2020 to September 2022.

None.

Using minute-by-minute MAP values during the first 24 hours postoperatively, the authors created 7 mutually exclusive MAP range bands (<55, 55-59, 60-64, 65-69, 70-74, 75-79, and ≥80 mmHg); the primary exposure was defined as the total number of minutes a patient spent within each MAP range band throughout this period. The primary outcome was AKI, identified between 24 hours and 7 days postoperatively. Multivariable logistic regression models quantified the association between increasing time spent in each MAP range band during the first 24 hours postoperatively, relative to a reference range band of 65 to 69 mmHg, and AKI. The mean patient age was 63.9 years (standard deviation, 12.8 years), with 1,313,568 observed MAP data points from 1,895,133 intensive care unit person-minutes during the first 24 hours postoperatively. After prespecified exclusions, AKI occurred in 190 patients (15.3%). There was no association between increasing time spent in any MAP range band, relative to time spent between 65 and 69 mmHg, and AKI. For example, the odds ratio for AKI per 15 minutes with MAP of 60 to 64 mmHg was 0.98 (95% confidence interval [CI], 0.88-1.08), and the odds ratio with MAP of 55 of 59 mmHg was 1.03 (95% CI, 0.93-1.13).

This study was unable to demonstrate an association between increasing time spent in any MAP range band during the first 24 hours postoperatively and AKI.