title: Potential drug sequestration during extracorporeal membrane oxygenation: results from an ex vivo experiment.
abstract: OBJECTIVE
  Using an ex vivo simulation model we set out to estimate the amount of drug lost due to sequestration within the extracorporeal circuit over time.
  
  
  METHODS
  Simulated closed-loop extracorporeal membrane oxygenation (ECMO) circuits were prepared using a 1.5-m2 silicone membrane oxygenator. Group A consisted of heparin, dopamine, ampicillin, vancomycin, phenobarbital and fentanyl. Group B consisted of epinephrine, cefazolin, hydrocortisone, fosphenytoin and morphine. Drugs were tested in crystalloid and blood-primed circuits. After administration of a one-time dose of drugs in the priming fluid, baseline drug concentrations were obtained (P0). A simultaneous specimen was stored for stability testing at 24 h (P4). Serial post-membrane drug concentrations were then obtained at 30 min (P1), 3 h (P2) and 24 h (P3) from circuit fluid.
  
  
  RESULTS
  One hundred and one samples were analyzed. At the end of 24 h in crystalloid-primed circuits, 71.8% of ampicillin, 96.7% of epinephrine, 17.6% of fosphenytoin, 33.3% of heparin, 17.5% of morphine and 87% of fentanyl was lost. At the end of 24 h in blood-primed extracorporeal circuits, 15.4% of ampicillin, 21% of cefazolin, 71% of voriconazole, 31.4% of fosphenytoin, 53.3% of heparin and 100% of fentanyl was lost. There was a significant decrease in overall drug concentrations from 30 min to 24 h for both crystalloid-primed circuits (p = 0.023) and blood-primed circuits (p = 0.04).
  
  
  CONCLUSIONS
  Our ex vivo study demonstrates serial losses of several drugs commonly used during ECMO therapy. Therapeutic concentrations of fentanyl, voriconazole, antimicrobials and heparin cannot be guaranteed in patients on ECMO.
authors.affiliation: Children's Hospital, Farley 517, Division of Critical Care Medicine, 300 Longwood Avenue, Boston 02115, MA, USA. nilesh.mehta@childrens.harvard.edu
authors.forename: Nilesh M
authors.initials: NM
authors.lastname: Mehta
authors.forename: David R
authors.initials: DR
authors.lastname: Halwick
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Dodson
authors.forename: John E
authors.initials: JE
authors.lastname: Thompson
authors.forename: John H
authors.initials: JH
authors.lastname: Arnold
mesh_terms: D015199:Extracorporeal Membrane Oxygenation; D006801:Humans; D008962:Models, Theoretical; D004364:Pharmaceutical Preparations / Q000008:administration & dosage / Q000032:analysis; D010599:Pharmacokinetics; D014481:United States
chemical_list: D004364:Pharmaceutical Preparations