The incidence of intraoperative hypotension in moderate to high risk patients undergoing non-cardiac surgery: A retrospective multicenter observational analysis

Study objective: Intraoperative hypotension is associated with perioperative morbidity. We undertook this project to describe the incidence of hypotension (defined as mean arterial pressure <65 mmHg). Design: Retrospective, observational study. Setting: This study was in the intraoperative setting. Patients: We studied 22,109 adult patients ASA 3 and 4 patients, undergoing surgeries >= 180 min, with arterial line monitoring, from January 1, 2017, to December 31, 2017. Interventions: None. Measurements: Our primary measurement was the number of minutes of primarily invasive mean arterial blood pressure below 65 mmHg. Additionally, we collected patient medical history data as classified by the Elixhauser Comorbidity Enhanced ICD-9-CM/ICD-10 CM Algorithm. Additional study variables included age, gender, BMI, preoperative blood pressure, ASA physical status classification, presence of absence of vasopressor infusion (phenylephrine, norepinephrine, vasopressin), estimated blood loss, amount of PRBCs administered, and surgical procedure type, characterized by body region on the basis of primary anesthesiology Current Procedural Terminology (CPT) code. Main results: The mean duration of MAP <65 mmHg was 28.2 min (SD 42.6). 88% of cases had at least one hypotensive event as defined as MAP <65 mmHg for 1 min. Across centers this varied from 83.2 to 91.6% of cases. The mean duration of hypotension ranged from 22.1 to 31.8 min. Conclusion: There continues to be a significant burden of hypotension (defined as MAP <65 mmHg) across our multicenter cohort of hospitals.