The Relationship between Intraoperative Blood Pressure Variability and all-Cause Mortality and Postoperative Acute Kidney Injury

Background: Low intraoperative blood pressure is linked with increased mortality and increased risk of acute kidney injury (AKI). The association between intraoperative blood pressure variability and postoperative outcome remains unclear.

Objective: To assess the association between intraoperative blood pressure variability and postoperative outcome.

Methods: This is a retrospective cohort study of consecutive adults who underwent surgery at the Lady Davis Carmel Medical Center between 1.1.2005-31.12.2015 of >120 minutes duration. Operations under local anesthesia and cardiac/vascular surgeries were excluded. Intraoperative invasive blood pressure variability was calculated using the generalized average real variability (ARV) equation and its association with all-cause mortality and AKI was assessed using Cox proportional hazard regression models.

Results: overall, 7677 patients (61.2% men, 83.8% elective surgeries) with mean age 66.1±13.4 years were included in the study. Compared to the lowest quartile of generalized ARV, the adjusted hazard ratio (HR) for all-cause 30 days mortality was 0.90 (95% CI, 0.67-1.22) in the second quartile, 0.76 (0.55-1.05) in the third quartile, and 0.68 (0.49-0.96) in the highest quartile. Compared to the lowest quartile of generalized ARV, the adjusted HR for AKI was 1.3(1.16-1.5) in the second quartile, 1.5(1.4-1.75) in the third quartile, and 1.6(1.4-1.9) in the highest quartile.

Conclusions: Intraoperative blood pressure variability estimated with the generalized ARV equation is inversely associated with the risk of all-cause mortality and directly associated with the risk of AKI.