SLR - March 2017 - Sarah J. Daigle

The Association Between Mild Intraoperative Hypotension and Stroke in General Surgery Patients

Reference: Hsieh JK, Dalton JE, Yang D, Farag ES, Sessler DI, Kurz AM. The Association Between Mild Intraoperative Hypotension and Stroke in General Surgery Patients. Anesth Analg. 2016 Oct;123(4):933–9.

Reviewed By: Sarah J. Daigle, DPM
Residency Program: St. Francis Hospital, Hartford, CT

Podiatric Relevance: Podiatric surgeons routinely take patients to the OR, and many of these patients may have several comorbidities, one of which may be hypertension. Although podiatric surgery is generally lower risk, many patients may be high risk. In general, it is important to understand and control a patient’s blood pressure in the perioperative period. In fact, this is one of the SCIP criteria. SCIP (Surgical Care Improvement Project) aims to reduce the incidence of surgical complications nationally by 25 percent. They recommend that patients on beta blockers take their medication within 24 hours of surgery and then restart regular therapy following surgery. Recently, hypotension has been identified as a risk factor for perioperative stroke. The POISE (Perioperative Ischemic Evaluation Study) trial in 2007 found an increased rate of death in patients receiving metoprolol vs. placebo for noncardiac surgery. Older literature identifies a relationship between postoperative hypotension and perioperative stroke whereas newer literature supports a relationship between intraoperative hypotension and perioperative stroke. Overall, the relationship remains unclear. This paper tests the hypothesis that intraoperative hypotension is associated with perioperative stroke.

Methods: This article is a propensity score-matched (4:1) case-control study with 502 patients: 398 controls and 104 stroke patients. Postoperative stroke was defined as those diagnosed up to 30 days following surgery. Nonneurological, noncardiac and noncarotid patients were evaluated. Intraoperative hypotension was measured as time-integrated area under a mean arterial pressure (MAP) of 70 mmHg.

Results: Hypotension (MAP < 70 mmHg) intraoperatively was observed in 74 percent of stroke cases and 78 percent of controls. There was no association between perioperative stroke and intraoperative hypotension measured. Severity of hypotension did not significantly differ in patients who did and did not have perioperative strokes. Postoperative hypotension may be a greater contributor to later-occurring strokes.

Conclusions: There was no association found between intraoperative hypotension and perioperative stroke, but a question remains as to the association of postoperative hypotension and stroke. Although this is not directly a podiatric problem, many of our patients have hypertension. Control of their hypertension before, during and after surgery is paramount. Prevention of hypotension throughout the perioperative may be equally as important to consider, especially in chronically ill patients. 

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