Intraoperative Mean Arterial Pressure Variability and 30-day Mortality in Patients Having Noncardiac Surgery

AbstractAbstract Average mean arterial pressure and mean pressure variability were nonlinearly related to 30-day mortality in noncardiac surgical patients. After adjusting for time-weighted average mean arterial pressure and other important covariables, low blood pressure variability as measured by an improved formula was still associated with higher 30-day mortality, but the differences were not clinically important. Anesthesiologists might thus pay more attention to overall trends in the mean blood pressure for a case than in the minute-to-minute variation. Background: Little is known about the relationship between intraoperative blood pressure variability and mortality after noncardiac surgery. Therefore, the authors tested the hypothesis that blood pressure variability, independent from absolute blood pressure, is associated with increased 30-day mortality. Methods: Baseline and intraoperative variables plus 30-day mortality were obtained for 104,401 adults having noncardiac surgery lasting 60 min or longer. In confounder-adjusted models, the authors evaluated the associations between 30-day mortality and both time-weighted average intraoperative mean arterial pressure (TWA-MAP) and measures of intraoperative MAP variability—including generalized average real variability of MAP (ARV-MAP) and SD of MAP (SD-MAP). Results: Mean ± SD TWA-MAP was 84 ± 10 mmHg, and ARV-MAP was 2.5 ± 1.3 mmHg/min. TWA-MAP was strongly related to 30-day mortality, which more than tripled as TWA-MAP decreased from 80 to 50 mmHg. ARV-MAP was only marginally related to 30-day mortality ( P = 0.033) after adjusting for TWA-MAP. Compared with median ARV-MAP, odds ratio (95% CI) for 30-day mortality was 1.14 (1.03 to 1.25) for low ARV-MAP (first quartile) and 0.94 (0.88 to 0.99) for high ARV-MAP (third quartile). Odds of 30-day mortality decreased as five-level categorized ARV-MAP increased (0.92; 0.87 to 0.99 for one category increase; P = 0.015). Secondarily, cumulative duration of MAP less than 50, 55, 60, 70, and 80 mmHg was associated with increased odds of 30-day mortality (all P < 0.001). Conclusion: Although lower mean arterial pressure is strongly associated with mortality, lower intraoperative blood pressure variability per se is only mildly associated with postoperative mortality after noncardiac surgery.