Population pharmacokinetics of remifentanil in critically ill patients receiving extracorporeal membrane oxygenation

Sedation and analgesia requirements during venovenous extracorporeal membrane oxygenation in acute respiratory distress syndrome patients

INTRODUCTION

The purpose of this study is to describe sedation and analgesia management, and identify the factors associated with increased demand for medication in acute respiratory distress syndrome (ARDS) patients receiving venovenous extracorporeal membrane oxygenation (VV-ECMO).

METHODS

This retrospective, single-center study included consecutive adult ARDS patients who received VV-ECMO for at least 24 hours from January 2018 to December 2020 in a comprehensive intensive care unit. The electronic medical records were retrospectively reviewed to collect data.

RESULTS

Forty-two adult patients meeting the inclusion criteria were included in the study. Midazolam, sufentanil, and remifentanil were main sedatives and analgesics used in the patient population. The morphine equivalents, representative of the demand for opioids, was 512.9 (IQR, 294.5, 798.2) mg/day. The midazolam equivalents, representative of benzodiazepine requirement, was 279.6 (IQR, 208.8, 384.5) mg/day. The levels of serum creatinine, total bilirubin, lactic acid, SOFA score, and APACHE Ⅱ score at cannulation were found to be associated with opiate or benzodiazepine requirements. Multiple linear regression analysis revealed a linear correlation between midazolam equivalents and morphine equivalents (p < 0.001). In addition, there was a negative linear correlation between Acute Physiology and Chronic Health Evaluation Ⅱ (APACHE Ⅱ) score and midazolam equivalents (p = 0.024).

CONCLUSIONS

The sedation and analgesia requirements of ARDS patients receiving VV-ECMO often increase simultaneously. More large-scale studies are needed to confirm the risk factors for increased sedation and analgesia needs in patients supported on VV-ECMO.

Harnessing Clinical Trial and Real-World Data Towards an Understanding of Sex Effects on Drug Pharmacokinetics, Pharmacodynamics and Efficacy

Increasing clinical data on sex-related differences in drug efficacy and toxicity has highlighted the importance of understanding the impact of sex on drug pharmacokinetics and pharmacodynamics. Intrinsic differences between males and females, such as different CYP enzyme activity, drug transporter expression or levels of sex hormones can all contribute to different responses to medications. However, most studies do not include sex-specific investigations, leading to lack of sex-disaggregated pharmacokinetic and pharmacodynamic data. Based available literature, the potential influence of sex on exposure-response relationship has not been fully explored for many drugs used in clinical practice, though population-based pharmacokinetic/pharmacodynamic modelling is well-placed to explore this effect. The aim of this review is to highlight existing knowledge gaps regarding the effect of sex on clinical outcomes, thereby proposing future research direction for the drugs with significant sex differences. Based on evaluated drugs encompassing all therapeutic areas, 25 drugs demonstrated a clinically meaningful sex differences in drug exposure (characterised by ≥ 50% change in drug exposure) and this altered PK was correlated with differential response.

Organ donation in patients on extracorporeal membrane oxygenation: considerations for determination of death and withdrawal of life support

The use of extracorporeal membrane oxygenation (ECMO) is increasing globally, although mortality in this setting remains high. Patients on ECMO may be potential organ donors in the context of withdrawal of life-sustaining measures (WLSM) or neurologic determination of death (NDD). Nevertheless, there are currently no Canadian standards to guide clinicians on NDD or WLSM for the purposes of organ donation in this patient population. Apnea testing remains fundamental to determining NDD and is an area where ECMO may alter routine procedures. In this review, we outline protocols for the performance of apnea testing and WLSM for patients supported with ECMO, highlighting important technical and physiologic considerations that may affect the determination of death. In addition, we review important considerations for NDD in ECMO, including management of potential confounders, strategies for controlling oxygen and carbon dioxide levels during apnea testing, and the appropriate use of ancillary tests to support NDD. In the context of ECMO support, there is limited evidence to guide NDD and WLSM for the purposes of organ donation. Drawing upon extensive clinical experience, we provide protocols for these processes and review other important considerations in an effort to maximize donor potential in this growing patient population.

Dose Optimization of Cefpirome Based on Population Pharmacokinetics and Target Attainment during Extracorporeal Membrane Oxygenation

To obtain the optimal dosage regimen in patients receiving extracorporeal membrane oxygenation (ECMO), we developed a population pharmacokinetics model for cefpirome and performed pharmacodynamic analyses. This prospective study included 15 patients treated with cefpirome during ECMO. Blood samples were collected during ECMO (ECMO-ON) and after ECMO (ECMO-OFF) at predose and 0.5 to 1, 2 to 3, 4 to 6, 8 to 10, and 12 h after cefpirome administration. The population pharmacokinetic model was developed using nonlinear mixed effects modeling and stepwise covariate modeling. Monte Carlo simulation was used to assess the probability of target attainment (PTA) and cumulative fraction of response (CFR) according to the MIC distribution. Cefpirome pharmacokinetics were best described by a two-compartment model. Covariate analysis indicated that serum creatinine concentration (SCr) was negatively correlated with clearance, and the presence of ECMO increased clearance and the central volume of distribution. The simulations showed that patients with low SCr during ECMO-ON had lower PTA than patients with high SCr during ECMO-OFF; so, a higher dosage of cefpirome was required. Cefpirome of 2 g every 8 h for intravenous bolus injection or 2 g every 12 h for extended infusion over 4 h was recommended with normal kidney function receiving ECMO. We established a population pharmacokinetic model for cefpirome in patients with ECMO, and appropriate cefpirome dosage regimens were recommended. The impact of ECMO could be due to the change in patient status on consideration of the small population and uncertainty in covariate relationships. Dose optimization of cefpirome may improve treatment success and survival in patients receiving ECMO. (This study has been registered at ClinicalTrials.gov under identifier NCT02581280.).

Isoflurane Sedation in Patients Undergoing Venoarterial Extracorporeal Membrane Oxygenation Treatment for Cardiogenic Shock-An Observational Propensity-Matched Study

The feasibility and hemodynamic effects of isoflurane sedation in cardiogenic shock in the presence of venoarterial extracorporeal membrane oxygenation treatment are currently unknown.

Design

Retrospective single-center study.

Setting

Cardiac ICU of Munich university hospital.

Patients/Subjects

Cardiogenic shock patients with venoarterial extracorporeal membrane oxygenation treatment under sedation with volatile isoflurane between November 2018 and October 2019 have been enrolled in this study and were matched by propensity score in a 1:1 ratio with IV sedated patients treated between January 2013 and November 2018 from the cardiogenic shock registry of the university hospital of Munich.

Measurements and Main Results

Isoflurane sedation was used in 32 patients with cardiogenic shock and venoarterial extracorporeal membrane oxygenation treatment. The mean age of conventionally sedated patients was 58.4 ± 13.8 years and 56.3 ± 11.5 years for patients with isoflurane sedation (p = 0.51). Administration of isoflurane was associated with lower IV sedative drug use during venoarterial extracorporeal membrane oxygenation treatment (86% vs 32%; p = 0.01). Mean systolic arterial pressure was similar (94.3 ± 12.6 vs 92.9 ± 10.5 mm Hg; p = 0.65), but mean heart rate was significantly higher in the conventional sedation group, when compared with the isoflurane group (85.2 ± 20.5 vs 74.7 ± 15.0 beats/min; p = 0.02). Catecholamine doses, venoarterial extracorporeal membrane oxygenation blood and gas flow, ventilation time (304 ± 143 vs 398 ± 272 hr; p = 0.16), bleeding complications bleeding academic research consortium 3a or higher (59.3% vs 65.3%; p = 0.76), and 30-day mortality (59.2% vs 63.4%, p = 0.80) were similar in both groups. The overall sedation costs per patient were significantly lower in the conventional group, when compared with the isoflurane group (537 ± 624 vs 1280 ± 837 €; p < 0.001).

Conclusions

Volatile sedation with isoflurane is feasible-albeit at higher costs-in patients with cardiogenic shock and venoarterial extracorporeal membrane oxygenation treatment and was not associated with higher catecholamine dosage or extracorporeal membrane oxygenation flow rate compared with IV sedation.

Perspectives on adjunctive use of ketamine for analgosedation during extracorporeal membrane oxygenation

Analgosedation on ECMO is more than the choice of any drug, it has to be context specific. Ketamine may be considered as an adjunctive therapy in patients requiring high-dose opioids and sedatives during ECMO support with difficulty to achieve a target RASS. Considering ketamine provides analgesia while maintaining airway reflexes, it could be useful for early ECMO weaning and use of ECMO in awake, non-intubated, spontaneously breathing patients with respiratory failure ('awake' ECMO), especially for patients having considerable waiting periods while being bridged to transplant. The hemodynamic effects of ketamine may provide the benefit of decreasing vasopressor requirements, thereby potentially improving microcirculation. In this context, the effects on end-organ function and the need for renal replacement therapy should be investigated. Pharmacokinetic and pharmacodynamic studies on ketamine ex- and in vivo are of utmost importance to delineate its pharmacological profile and effectiveness during ECMO therapy and to create admissible future study hypothesis.

A Population Pharmacokinetic and Pharmacodynamic Analysis of RP5063 Phase 2 Study Data in Patients with Schizophrenia or Schizoaffective Disorder

Background and Objective

RP5063 is a novel multimodal dopamine (D)–serotonin (5-HT) stabilizer possessing partial agonist activity for D_2/3/4 and 5-HT_1A/2A, antagonist activity for 5-HT_2B/2C/7, and moderate affinity for the serotonin transporter. Phase 2 trial data analysis of RP5063 involving patients with schizophrenia and schizoaffective disorder defined: (1) the pharmacokinetic profile; and (2) the pharmacokinetic/pharmacodynamic relationships.

Methods

Pharmacokinetic sample data (175 patients on RP5063; 28 doses/patient) were analyzed, utilized one- and two-compartment models, and evaluated the impact of covariates. Pharmacodynamic analysis involved development of an E_max model.

Results

The pharmacokinetic analysis identified a one-compartment model incorporating body mass index influence on volume as the optimum construct, with fixed-effect parameters: (1) oral clearance (Cl/F), 5.11 ± 0.11 L/h; (2) volume of distribution (V_c/F), 328.00 ± 31.40 L; (3) absorption constant (ka) 0.42 ± 0.17 h⁻¹; (4) lag time (t lag) of 0.41 ± 0.02 h; and (5) a calculated half-life of 44.5 h. Pharmacokinetics were linear related to dose. An E_max model for total Positive and Negative Syndrome Scale (PANSS) scores as the response factor against cumulative area under the curve (AUC) provided fixed-effect estimates: (1) E_o = 87.3 ± 0.71 (PANSS Units; pu); (2) E_max = − 31.60 ± 4.05 (pu); and (3) AUC₅₀ = 89.60 ± 30.10 (µg·h/mL). The predicted PANSS improvement reflected a clinical dose range of 5–30 mg.

Conclusions

Pharmacokinetics of RP5063 behaved predictably and consistently. Pharmacodynamics were characterized using an E_max model, reflecting total PANSS score as a function of cumulative AUC, that showed high predictability and low variability when correlated with actual observations.

Electronic supplementary material

The online version of this article (10.1007/s13318-018-0472-z) contains supplementary material, which is available to authorized users.

Pharmacokinetics and Extracorporeal Membrane Oxygenation in Adults: A Literature Review

Extracorporeal membrane oxygenation is a rapidly emerging treatment for respiratory or cardiac failure and is used as a bridge to recovery, transplant, or destination therapy. Adult patients receiving extracorporeal membrane oxygenation also receive significant amounts of pharmacotherapy. Although the body of literature on extra-corporeal membrane oxygenation in general is extensive, only a few publications focus on pharmacokinetic changes related to extracorporeal membrane oxygenation in adults. Understanding pharmacokinetics in adult patients receiving extracorporeal membrane oxygenation is important to correctly select and dose medications in this patient population. This article reviews published studies of the effects of extracorporeal membrane oxygenation on pharmacokinetics in adults.

In Vitro Adsorption of Analgosedative Drugs in New Extracorporeal Membrane Oxygenation Circuits

OBJECTIVE

Evaluate drug disposition of sedatives and analgesics in the Xenios/Novalung extracorporeal membrane oxygenation circuits.

DESIGN

In vitro experimental study.

SETTING

Erasmus MC - Sophia Children's Hospital, Rotterdam, The Netherlands.

SUBJECTS

Nine closed-loop extracorporeal membrane oxygenation circuits, made up of the iLA Activve console with four different iLA Activve kits: two X-lung kits, two iLA-Activve iLA kits, two MiniLung kits, and three MiniLung petite kits.

INTERVENTIONS

The circuits were primed with fresh whole blood and maintained under physiologic conditions (pH/temperature) throughout 24 hours. Paracetamol, morphine, midazolam, fentanyl, and sufentanil were injected as standard age-related doses into nine closed-loop extracorporeal membrane oxygenation circuits.

MEASUREMENTS AND MAIN RESULTS

Pre-membrane (P2) blood samples were obtained prior to drug injection and after injection at 2, 10, 30, 180, 360 minutes, and at 24 hours. A control sample at 2 minutes was collected for spontaneous drug degradation testing at 24 hours. Two hundred sixteen samples were analyzed. After correction for the spontaneous drug degradation, the mean drug loss at 24 hours was paracetamol 49%, morphine 51%, midazolam 40%, fentanyl 84%, sufentanil 83%. Spontaneous degradation was paracetamol 6%, morphine 0%, midazolam 11%, fentanyl 4%, and sufentanil 0%. The decline of drug concentration over time was more pronounced for the more lipophilic drugs.

CONCLUSIONS

Loss of highly lipophilic drugs in the extracorporeal membrane oxygenation circuits at 24 hours was remarkable. Drug loss is comparable with other hollow fiber extracorporeal membrane oxygenation systems but less than in silicone-based membranes especially in the first hours after injection.