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Anesthesiology. 2010 Jan;112(1):25-33. doi: 10.1097/ALN.0b013e3181c5dd81.

Acute surgical anemia influences the cardioprotective effects of beta-blockade: a single-center, propensity-matched cohort study.

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  • 1Department of Health Policy Management and Evaluation, University of Toronto, Toronto, Ontario, Canada. scott.beattie@uhn.on.ca

Abstract

BACKGROUND:

Despite decreasing cardiac events, perioperative beta-blockade also increases perioperative stroke and mortality. Major bleeding and/or hypotension are independently associated with these outcomes. To investigate the hypothesis that beta-blockade limits the cardiac reserve to compensate for acute surgical anemia, the authors examined the relationship between cardiac events and acute surgical anemia in patients with and without beta-blockade.

METHODS:

The records of all noncardiac, nontransplant surgical patients between March 2005 and June 2006 were retrospectively retrieved. The primary outcome was a composite that comprised myocardial infarction, nonfatal cardiac arrest, and in-hospital mortality (major adverse cardiac event). The lowest recorded hemoglobin in the first 3 days defined nadir hemoglobin. Propensity scores estimating the probability of receiving a perioperative beta-blocker were used to match (1:1) patients who did or did not receive beta-blockers postoperatively. The relationship between nadir hemoglobin and major adverse cardiac event was then assessed.

RESULTS:

This analysis identified 4,387 patients in whom nadir hemoglobin could be calculated; 1,153 (26%) patients were administered beta-blockers within the first 24 h of surgery. Propensity scores created 827 matched pairs that were well balanced for all measured confounders. Major adverse cardiac event occurred in 54 (6.5%) beta-blocked patients and in 25 (3.0%) beta-blocker naive patients (relative risk 2.38; 95% CI 1.43-3.96; P = 0.0009). The restricted cubic spline relationship demonstrated that this difference was restricted to those patients in whom the hemoglobin decrease exceeded 35% of the baseline value.

CONCLUSIONS:

beta-Blocked patients do not seem to tolerate surgical anemia when compared with patients who are naive to beta-blockers. Prospective studies are required to validate these findings.

PMID:
20032700
[PubMed - indexed for MEDLINE]
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