Intraoperative Blood Pressure What Patterns Identify Patients at Risk for Postoperative Complications?

Abstract

While monitoring blood pressure is a routine part of intraoperative management, several methods have been proposed to characterize intraoperative hemodynamic patterns as predictors of postoperative complications. In this prospective study of a high-risk population of hypertensive and diabetic patients undergoing elective noncardiac surgery, one objective was to compare different approaches to the assessment of intraoperative hemodynamic patterns to identify those patterns most likely to be associated with postoperative complications. Twenty-one per cent of the 254 patients sustained cardiac or renal complications after operation. Patients with more than 1 hour of greater than or equal to 20-mmHg decreases in mean arterial pressure (MAP) or patients with less than 1 hour of greater than or equal to 20-mmHg decreases and more than 15 minutes of greater than or equal to 20-mmHg increases were at highest risk for postoperative complications. Together these two patterns had a 46% sensitivity rate and a 70% specificity rate in predicting postoperative complications. Using 20% change in intraoperative MAP produced results nearly identical to 20-mmHg changes. When the duration of 20-mmHg changes was accounted for, changes of a greater magnitude (e.g., 40 mmHg) were not significant independent predictors of complications. The use of the mean difference from preoperative MAP was misleading because patients who experienced both high and low MAPs tended to have nearly normal mean MAPs, but high complication rates. The absolute magnitude of intraoperative MAPs, regardless of the preoperative levels, also was evaluated. The overall mean intraoperative MAP was not a significant predictor of complications. Specific intraoperative MAPs (e.g., less than 70 mmHg and more than 120 mmHg) also were evaluated. While neither was a significant predictor, there was a trend for increased complications among patients whose MAPs decreased to less than 70 mmHg. Intraoperative blood pressure should be analyzed in relation to the patient's preoperative blood pressure. Prolonged changes of more than 20 mmHg or 20% in relation to preoperative levels were significantly related to complications.

Acute Kidney Injury following Cardiac Surgery: Role of Perioperative Blood Pressure Control

“…It is important to note that relatively small changes in perioperative BP can substantially affect postoperative risk. In one study [37], a cut-off level for change from preoperative level in MAP of >20 mm Hg or >20% was sufficient to identify surgical patients at significantly increased cardiac or renal risk (composite endpoint). This level of change can be clinically important, as experimental studies in dogs indicate that autoregulatory mechanisms are only capable of maintaining perfusion of the coronary and renal circulations within physiological limits if systemic pressures remain within the ‘autoregulatory range’ (for the kidney, approximately 75 to >160 mm Hg) [38].…”

Risk Index for Perioperative Renal Dysfunction/Failure

“…Whereas preoperative mean arterial pressure has been identified as a reference to guide intraoperative blood pressure management, 15,18 -20 preoperative PP has not. Charlson et al 21 noted that 21% of noncardiac patients had cardiac or renal complications if intraoperative mean arterial pressure was Ͻ20% of baseline for Ͼ1 hour or Ͼ20% for Ͼ15 minutes. They also reported increased cerebral and renal dysfunction when mean arterial pressure was maintained at Ͻ70 to 80 mm Hg during cardiac surgery with CPB, 18 whereas others 19 reported no differences in renal outcomes when mean arterial pressure was maintained at 50 mm Hg during CPB.…”

A Novel Morbidity Prediction Model for Head and Neck Oncosurgery

“…Hypertensive vascular disease, which can be asymptomatic until arterial stenosis is severe, is common in head and neck cancer patients as the risk factors for both cancer and atherosclerosis are similar. In a prospective study of a high risk population of hypertensives undergoing non cardiac surgery prolonged changes of blood pressure more than 20% were associated with post operative complications [20]. This could probably lead to compromised blood supply leading to flap failure and tissue necrosis.…”