Preliminary Studies of the Effects of Extracorporeal Membrane Oxygenator on the Disposition of Common Pediatric Drugs

摘要

There is an increased use of extracorporeal membrane oxygenation (ECMO) in the last 15 years for critically ill neonates. While receiving ECMO therapy, the critically ill infant needs various medications. We performed an in vitro study to evaluate the potential effect of the membrane oxygenator on drug extraction. Two closed ECMO circuits were set up at rates of 320 ml/min. One circuit was new and the other was used clinically for 5 days. Morphine at 8 ng/ml, gentamicin 10 mu;g/ml, vancomycin 40 mu;g/ml, phenobarbital 20 mu;g/ml, and phenytoin 20 mu;g/ml were injected into the circuit at 1-h intervals. Blood samples were drawn from the circuit at 10, 30, 60, and 240 minutes after injection. In the new circuit, drugs were eliminated as follows: vancomycin 36percnt;, gentamicin 10percnt;, phenobarbital 17percnt;, phenytoin 43percnt;, morphine 36percnt;. In the used system, levels fell to a much smaller extent: vancomycin 11percnt;, phenobarbital 6percnt;, gentamicin 0percnt;, phenytoin 0percnt;, and morphine 16percnt;. In a child receiving 20 mu;g/kg/h infusion of morphine, steady-state concentrations of 68.2 ng/ml fell to 11.6 ng/ml after changing the membrane. Our data indicate that the ECMO is associated with lowering of the concentrations of commonly used medications and that this process may depend partially on how new the membrane is. Before these changes may lead to new dosing guidelines for small children receiving ECMO, more experiments with new and used systems are warranted, as well as with different types of ECMO.