In Vitro Drug Adsorption and Plasma Free Hemoglobin Levels Associated With Hollow Fiber Oxygenators in the Extracorporeal Life Support (ECLS) Circuit

Abstract

The purpose of this study was to identify the percentage of fentanyl or morphine sulfate lost from adhesion to either the polyvinylchloride (PVC) tubing or the surface of two different hollow fiber oxygenators used in current extracorporeal life support circuits and to identify any difference in the plasma free hemoglobin (PFH) levels generated when using these oxygenator and/or drug combinations. For each drug examined, six simple circuits were assembled; for each drug, two circuits contained tubing without an oxygenator (control), two circuits contained the Jostra Quadrox D (Maquet Cardiopulmonary, AG Hirrlingen, Germany), and two circuits contained the Terumo Baby Rx (Terumo Cardiovascular Systems Corp., Ann Arbor, MI). Fentanyl or morphine sulfate was added to yield initial circuit concentrations equal to 1430 ng/mL, respectively. Throughout the 6-hour in vitro testing, samples to evaluate the drug and PFH levels were drawn at various time intervals. Significance in this study is defined as p < .05. Fentanyl’s initial adsorption seems to be 80% in circuits without oxygenators, 86% in the circuits containing the Quadrox D oxygenator, and 83% in the circuits with the Baby Rx oxygenator. Morphine sulfate seems to be initially adsorbed at a rate of 40% in all circuits and does not seem to be adsorbed by either of the tested oxygenators. The PFH levels were significantly (p < .05) elevated in the fentanyl circuits. The type of oxygenator does not seem to play a significant role in drug adsorption. During this in vitro study, the majority of both drugs were lost to the PVC tubing. The type of oxygenator did not seem to significantly affect PFH. However, fentanyl in any combination or alone was associated with increased PFH levels.