Early vancomycin, amikacin and gentamicin concentrations in pulmonary artery and pulmonary tissue are not affected by VA ECMO (venoarterial extracorporeal membrane oxygenation) in a pig model of prolonged cardiac arrest

Pharmacokinetics of Amikacin in Critical Care Patients on Extracorporeal Device

In this study, we evaluate the effect of extracorporeal membrane oxygenation (ECMO) and ventricular assist devices (Levitronix) on the pharmacokinetic of amikacin in critically ill patients. Twelve patients with ECMO and three with Levitronix devices who started treatment with amikacin were included. Amikacin pre (Cmax) and post (Cmin) dose serum concentrations were measured during the first 72-96 hours of treatment initiation. Pharmacokinetic parameters were performed by Bayesian adjustment. The median initial dose was 1,000 mg (range: 600-1,400 mg). Mean plasma concentrations were Cmax 58.6 mg/L (17.0 mg/L); Cmin 9.58 mg/L (7.8 mg/L). Patients with an ECMO device had a higher volume of distribution (0.346 [0.033] vs. 0.288 [0.110] L/kg) and a lower plasma clearance (1.58 [0.21] vs. 3.73 [1.03] L/h) than the control group. This phenomenon was also observed in those patients with simultaneous use of ECMO and hemodilafiltration. For patients with Levitronix system, no significant alterations in the volume of distribution were observed, although a lower plasma clearance was noticed. Placement of ECMO devices alters the pharmacokinetic parameters of amikacin in the critically ill patients and should be considered when selecting the initial dose.

Predictors of insufficient peak amikacin concentration in critically ill patients on extracorporeal membrane oxygenation

Background

Amikacin infusion requires targeting a peak serum concentration (C_max) 8–10 times the minimal inhibitory concentration, corresponding to a C_max of 60–80 mg/L for the least susceptible bacteria to theoretically prevent therapeutic failure. Because drug pharmacokinetics on extracorporeal membrane oxygenation (ECMO) are challenging, we undertook this study to assess the frequency of insufficient amikacin C_max in critically ill patients on ECMO and to identify relative risk factors.

Methods

This was a prospective, observational, monocentric study in a university hospital. Patients on ECMO who received an amikacin loading dose for suspected Gram-negative infections were included. The amikacin loading dose of 25 mg/kg total body weight was administered intravenously and C_max was measured 30 min after the end of the infusion. Independent predicators of C_max < 60 mg/L after the first amikacin infusion were identified with mixed-model multivariable analyses. Various dosing simulations were performed to assess the probability of reaching 60 mg/L < C_max < 80 mg/L.

Results

A total of 106 patients on venoarterial ECMO (VA-ECMO) (68%) or venovenous-ECMO (32%) were included. At inclusion, their median (1st; 3rd quartile) Sequential Organ-Failure Assessment score was 15 (12; 18) and 54 patients (51%) were on renal replacement therapy. Overall ICU mortality was 54%. C_max was < 60 mg/L in 41 patients (39%). Independent risk factors for amikacin under-dosing were body mass index (BMI) < 22 kg/m² and a positive 24-h fluid balance. Using dosing simulation, increasing the amikacin dosing regimen to 30 mg/kg and 35 mg/kg of body weight when the 24-h fluid balance is positive and the BMI is ≥ 22 kg/m² or < 22 kg/m² (Table 3), respectively, would have potentially led to the therapeutic target being reached in 42% of patients while reducing under-dosing to 23% of patients.

Conclusions

ECMO-treated patients were under-dosed for amikacin in one third of cases. Increasing the dose to 35 mg/kg of body weight in low-BMI patients and those with positive 24-h fluid balance on ECMO to reach adequate targeted concentrations should be investigated.

Electronic supplementary material

The online version of this article (10.1186/s13054-018-2122-x) contains supplementary material, which is available to authorized users.

Pharmacotherapy during pediatric extracorporeal membrane oxygenation: a review

INTRODUCTION

Pediatric critical illness and associated alterations in organ function can change drug pharmacokinetics (PK). Extracorporeal membrane oxygenation (ECMO), a life-saving therapy for severe cardiac and/or respiratory failure, causes additional PK alterations that affect drug disposition.

AREAS COVERED

The purposes of this review are to discuss the PK changes that occur during ECMO, the associated therapeutic implications, and to review PK literature relevant to pediatric ECMO. We discuss various classes of drugs commonly used for pediatric patients on ECMO, including sedatives, analgesics, antimicrobials and cardiovascular drugs. Finally, we discuss future areas of research and recommend strategies for future pediatric ECMO pharmacologic investigations.

EXPERT OPINION

Clinicians caring for pediatric patients treated with ECMO must have an understanding of PK alterations that could lead to either therapeutic failures or increased drug toxicity during this life-saving therapy. Limited data currently exist for optimal drug dosing in pediatric populations who are treated with ECMO. While there are clear challenges to conducting and analyzing data associated with clinical pharmacokinetic-pharmacodynamic studies of children on ECMO, we present techniques to address these challenges. Improved understanding of the physiology and drug disposition during ECMO combined with PK-PD modeling will allow for more adaptable and individualized dosing schemes.