Pharmacokinetics of Ketamine at Dissociative Doses in an Adult Patient With Refractory Status Asthmaticus Receiving Extracorporeal Membrane Oxygenation Therapy

Purpose: First-line management of severe asthma exacerbations include the use of inhaled short-acting beta-agonists, anticholinergics, and systemic corticosteroids. Continuous intravenous ketamine given at dissociative doses may be a pharmacologic option in patients who are intubated with life-threatening severe bronchospasm unresponsive to standard therapy. We describe the case of a 44-year-old man admitted to the intensive care unit for status asthmaticus requiring intubation and mechanical ventilation. Methods: The patient developed severe refractory hypercapnic respiratory failure necessitating additional respiratory support with veno-venous extracorporeal membrane oxygenation (ECMO) therapy. Ketamine treatment was initiated at 0.5 mg/kg/h continuous infusion on the day of admission for pain control and required up-titration to 2 mg/kg/h by intensive care unit day 4 for bronchodilation. Whole blood samples were obtained for pharmacokinetic analysis of ketamine during ECMO. Findings: The plasma concentration at steady state was 1018.7 ng/mL, with an estimated clearance of 1.96 L/kg/h after up-titration. The V-d was 14.18 L/kg, the k(e) was 0.14 hr(-1), and the t(1/2) was 5 hours. Implications: Compared with healthy adults, there was a 6.5-fold increase in the V-d. However, the V-d was similar compared with critically ill patients not receiving ECMO. Further studies should focus on the effect of ECMO on ketamine pharmacokinetic properties. (C) 2019 Elsevier Inc. All rights reserved.