Plasma Free Hemoglobin Is an Independent Predictor of Mortality among Patients on Extracorporeal Membrane Oxygenation Support.

Hesham R Omar,Collin Sprenker,Stephanie Socias,Enrico M Camporesi,Christiano Caldeira,Mehdi Mirsaeidi,Devanand Mangar,Giacomo Frati

doi:10.1371/journal.pone.0124034

Abstract

BackgroundHemolysis is common in all extracorporeal circuits as evident by the elevated plasma free hemoglobin (PFHb) level. We investigated whether increased hemolysis during extracorporeal membrane oxygenation (ECMO) is an independent mortality predictor.MethodsWe performed a retrospective observational study of consecutive subjects who received ECMO at a tertiary care facility from 2007-2013 to investigate independent predictors of in-hospital mortality. We examined variables related to patient demographics, comorbidities, markers of hemolysis, ECMO characteristics, transfusion requirements, and complications. 24-hour PFHb> 50 mg/dL was used as a marker of severe hemolysis.Results154 patients received ECMO for cardiac (n= 115) or pulmonary (n=39) indications. Patients’ mean age was 51 years and 75.3% were males. Compared to nonsurvivors, survivors had lower pre-ECMO lactic acid (p=0.026), lower 24-hour lactic acid (p=0.023), shorter ECMO duration (P=0.01), fewer RBC transfusions on ECMO (p=0.008) and lower level of PFHb 24-hours post ECMO implantation (p=0.029). 24-hour PFHb> 50 mg/dL occurred in 3.9 % versus 15.5% of survivors and nonsurvivors, respectively, p=0.002. A Cox proportional hazard analysis identified PFHb> 50 mg/dL 24-hours post ECMO as an independent predictor of mortality (OR= 3.4, 95% confidence interval: 1.3 – 8.8, p= 0.011).ConclusionPFHb> 50 mg/dL checked 24-hour post ECMO implantation is a useful tool to predict mortality. We propose the routine checking of PFHb 24-hours after ECMO initiation for early identification and treatment of the cause of hemolysis.

Highlights

Extracorporeal membrane oxygenation (ECMO) has shown promising results for critically ill patients, requiring cardiopulmonary support, who are otherwise expected to die [1,2]
We examined variables related to patient demographics, comorbidities, markers of hemolysis, extracorporeal membrane oxygenation (ECMO) characteristics, transfusion requirements, and complications. 24-hour plasma free hemoglobin (PFHb)> 50 mg/dL was used as a marker of severe hemolysis
Survivors had lower pre-ECMO lactic acid (p=0.026), lower 24-hour lactic acid (p=0.023), shorter ECMO duration (P=0.01), fewer RBC transfusions on ECMO (p=0.008) and lower level of PFHb 24-hours post ECMO implantation (p=0.029). 24-hour PFHb> 50 mg/dL occurred in 3.9 % versus 15.5% of survivors and nonsurvivors, respectively, p=0.002

Summary

Introduction

Extracorporeal membrane oxygenation (ECMO) has shown promising results for critically ill patients, requiring cardiopulmonary support, who are otherwise expected to die [1,2]. Patients receiving ECMO support experience an approximate 60–75% in-hospital mortality rate [3,4,5,6] due to severity of the underlying pathology and high incidence of multiple organ failure, despite improvement in intensive care management and advances in ECMO hardware technology. The high cost and low survival rates in ECMO subjects mandate an awareness of determinants of adverse outcomes for ideal patient selection to avoid providing futile care. We investigated whether increased hemolysis during extracorporeal membrane oxygenation (ECMO) is an independent mortality predictor

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