What is the most likely reason an agitated patient on extracorporeal membrane oxygenation (ECMO) is not properly responding to usual and adequate doses of pharmacological agents?
The ECMO circuit is comprised of polyvinyl chloride (PVC) tubing and membranes with a large surface area. Most psychotropic agents as well as morphine, fentanyl and propofol are lipophilic and highly protein bound, resulting in significant sequestration in the ECMO circuit. Hydrophilic drugs such as beta-lactam antibiotics exhibit an increased volume of distribution due to hemodilution. In both cases, loading and/or maintenance doses may need to be increased.
Publication reference : Shekar K et al. Pharmacokinetic changes in patients receiving extracorporeal membrane oxygenation. J Crit Care 2012; 27: 741.e9–741.e18 Reference URL:https://pubmed.ncbi.nlm.nih.gov/22520488/