Association Between Intraoperative Hypotension and Postoperative Adverse Outcomes in Patients Undergoing Vascular Surgery – A Retrospective Observational Study

Objective: Intraoperative hypotension (IOH) is associated with adverse outcomes. It could be challenging to define IOH in vascular surgical patients with increased baseline blood pressure (BP). The authors studied the relationship between (1) absolute and relative BP thresholds of IOH, (2) preoperative pulse pressure (PP) and isolated systolic hypertension, and (3) endovascular versus open surgical approach with adverse outcomes in vascular surgical patients. Design: Retrospective observational study. Setting: Teaching hospital. Patients: A total of 566 vascular surgical patients from 2011 to 2018. Intervention: None. Measurements and Main Results: BP thresholds were as follows: IOH - absolute mean arterial pressure (MAP) <65 mmHg, relative MAP >20% decrease from baseline, preoperative PP hypertension - PP >40 mmHg, isolated systolic hypertension - baseline systolic BP ≥140 mmHg with diastolic BP <90 mmHg. Thresholds were characterized by (1) total duration and (2) area under the curve. Primary outcome was a composite of postoperative in-hospital complications (acute kidney injury, stroke, myocardial infarction, congestive heart failure, and mortality). Forty-six (8.1%) patients had in-hospital complications. Only IOH duration-MAP <65 mmHg (odds ratio 1.01; 95% confidence interval 1.00-1.02; p = 0.004) was significantly associated with outcome. No associations were found with MAP >20% decrease from baseline and preoperative BP. Significant interaction was observed with the surgical approach and outcome (p = 0.031), which was stronger after 60 minutes of IOH in endovascular approach. Conclusion: Longer periods of IOH (MAP <65 mmHg for >60 minutes) during endovascular surgery were associated with adverse outcomes. Relative fall in BP from baseline, preoperative isolated systolic, and PP hypertension were not associated with postoperative complications.