Impaired Pharmacokinetics of Amiodarone under Veno-Venous Extracorporeal Membrane Oxygenation: From Bench to Bedside

BACKGROUND

Adjusting drug therapy under veno-venous extracorporeal membrane oxygenation (VV ECMO) is challenging. Although impaired pharmacokinetics (PK) under VV ECMO have been reported for sedative drugs and antibiotics, data about amiodarone are lacking. We evaluated the pharmacokinetics of amiodarone under VV ECMO both in vitro and in vivo.

METHODS

In vitro: Amiodarone concentration decays were compared between closed-loop ECMO and control stirring containers over a 24 h period. In vivo: Potassium-induced cardiac arrest in 10 pigs with ARDS, assigned to either control or VV ECMO groups, was treated with 300 mg amiodarone injection under continuous cardiopulmonary resuscitation. Pharmacokinetic parameters Cmax, Tmax AUC and F were determined from both direct amiodarone plasma concentrations observation and non-linear mixed effects modeling estimation.

RESULTS

An in vitro study revealed a rapid and significant decrease in amiodarone concentrations in the closed-loop ECMO circuitry whereas it remained stable in control experiment. In vivo study revealed a 32% decrease in the AUC and a significant 42% drop of Cmax in the VV ECMO group as compared to controls. No difference in Tmax was observed. VV ECMO significantly modified both central distribution volume and amiodarone clearance. Monte Carlo simulations predicted that a 600 mg bolus of amiodarone under VV ECMO would achieve the amiodarone bioavailability observed in the control group.

CONCLUSIONS

This is the first study to report decreased amiodarone bioavailability under VV ECMO. Higher doses of amiodarone should be considered for effective amiodarone exposure under VV ECMO.

Feasibility of sedation with sevoflurane inhalation via AnaConDa for Covid-19 patients under venovenous extracorporeal membrane oxygenation

Critical care centers around the world have faced a shortage of intravenous sedatives caused by the coronavirus pandemic. Many patients infected with SARS-CoV-2 virus develop severe Acute Respiratory Distress syndrome (ARDS) for which some of them are supported by extra corporeal membrane oxygenation. Under these circumstances, the pharmacokinetics of the sedatives is modified. We observed that many of our COVID-19 infected patients receiving Extracorporeal Membrane Oxygenator (ECMO) require high doses of intravenous drugs. Continuous sedation with halogenated gases in the intensive care unit has shown many benefits on systemic inflammation and offers the possibility of a rapid recovery of consciousness. In this article we describe 3 cases that show the feasibility of sedation with sevoflurane via AnaConDa (Sedana Medical AB, Danderyd, Sweden) for Covid-19 patients under ECMO. Halogenated drugs could be considered as an interesting alternative to intravenous sedatives especially in the context of drug shortage.

Bivalirudin versus heparin as an anticoagulant during extracorporeal membrane oxygenation: a case-control study

OBJECTIVE

Heparin-based anticoagulation for patients undergoing extracorporeal membrane oxygenation has many limitations, including a high risk of heparin-induced thrombocytopenia. However, little experience with other anticoagulants in these patients has been described. The aim of this study was to compare bivalirudin-based anticoagulation with heparin-based protocols in a population of patients treated with venovenous or venoarterial extracorporeal membrane oxygenation.

DESIGN

In this case-control study, 10 patients received bivalirudin (cases) and 10 heparin (controls). The target activated partial thromboplastin time (aPTT) was 45 to 60 seconds.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

aPTT variations >20% of the previous value were much more frequent in patients treated with heparin than in patients receiving bivalirudin (52 v 24, p < 0.001). The number of corrections of the anticoagulant dose was higher in the heparin group compared with the bivalirudin group (58 v 51), although it did not reach statistical significance. Bleeding, thromboembolic complications, extracorporeal membrane oxygenation (ECMO) support duration, mortality, and the number of episodes of aPTT >80 seconds were not different between the 2 groups. A further analysis was performed in the bivalirudin group according to the presence of acute renal failure requiring continuous venovenous hemofiltration. The median bivalirudin dose in patients with or without hemofiltration was 0.041 (0.028-0.05) mg/kg/h and 0.028 (0-0.041) mg/kg/h, respectively (p = 0.2).

CONCLUSIONS

Bivalirudin-based anticoagulation may represent a new method of anticoagulation for reducing thromboembolic and bleeding complications, which still jeopardize the application of extracorporeal membrane oxygenation. Moreover, bivalirudin is free from the risk of heparin-induced thrombocytopenia. Higher doses of bivalirudin may be needed in patients undergoing hemofiltration.