Technical-Induced Hemolysis in Patients with Respiratory Failure Supported with Veno-Venous ECMO - Prevalence and Risk Factors.

Ingo Ahrens,Karla Lehle,Thomas Müller,Florian Zeman,Dirk Lunz,Laszlo Göbölös,Matthias Lubnow,Hans-Peter Wendel,Christof Schmid,Alois Philipp

doi:10.1371/journal.pone.0143527

Abstract

The aim of the study was to explore the prevalence and risk factors for technical-induced hemolysis in adults supported with veno-venous extracorporeal membrane oxygenation (vvECMO) and to analyze the effect of hemolytic episodes on outcome. This was a retrospective, single-center study that included 318 adult patients (Regensburg ECMO Registry, 2009–2014) with acute respiratory failure treated with different modern miniaturized ECMO systems. Free plasma hemoglobin (fHb) was used as indicator for hemolysis. Throughout a cumulative support duration of 4,142 days on ECMO only 1.7% of the fHb levels were above a critical value of 500 mg/l. A grave rise in fHb indicated pumphead thrombosis (n = 8), while acute oxygenator thrombosis (n = 15) did not affect fHb. Replacement of the pumphead normalized fHb within two days. Neither pump or cannula type nor duration on the first system was associated with hemolysis. Multiple trauma, need for kidney replacement therapy, increased daily red blood cell transfusion requirements, and high blood flow (3.0–4.5 L/min) through small-sized cannulas significantly resulted in augmented blood cell trauma. Survivors were characterized by lower peak levels of fHb [90 (60, 142) mg/l] in comparison to non-survivors [148 (91, 256) mg/l, p≤0.001]. In conclusion, marked hemolysis is not common in vvECMO with modern devices. Clinically obvious hemolysis often is caused by pumphead thrombosis. High flow velocity through small cannulas may also cause technical-induced hemolysis. In patients who developed lung failure due to trauma, fHb was elevated independantly of ECMO. In our cohort, the occurance of hemolysis was associated with increased mortality.

Highlights

The application of extracorporeal membrane oxygenation [ECMO] for patients with refractory respiratory failure failing conventional therapy has increased considerably [1] with improvement on outcome [2,3,4,5]
It was shown that only one third of pediatric patients on ECMO were free of hemolysis, but almost 7% displayed severe hemolysis with Free plasma hemoglobin (fHb) values larger than 1000 mg/L [27]
Activation and destruction of platelets may be a more suitable parameter to detect subtle injury. This is the first study with a large cohort of adult patients treated with veno-venous extracorporeal membrane oxygenation (vvECMO) which investigated the incidence and possible causes of hemolysis

Summary

Introduction

The application of extracorporeal membrane oxygenation [ECMO] for patients with refractory respiratory failure failing conventional therapy has increased considerably [1] with improvement on outcome [2,3,4,5]. Major contributors of technical-induced hemolysis may consist of sublethal damage to erythrocytes by shear stress [9,10,11], high extracorporeal blood flow [12], cavitation [13], and pressure changes within the oxygenator [14]. As a result of red blood cell [RBC] destruction, the levels of free plasma hemoglobin [fHb] and lactate dehydrogenase [LDH] can rise significantly during ECMO therapy [15,16].

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