Opioid sensitivity in treated and untreated obstructive sleep apnoea: a prospective cohort study.

BACKGROUND: Opioid administration to patients with obstructive sleep apnoea (OSA) is controversial because they are believed to be more sensitive to opioids. However, objective data on opioid effects in OSA are lacking. We tested the hypothesis that subjects with untreated OSA have increased sensitivity to opioids compared with subjects without OSA, or with OSA treated with continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BIPAP). METHODS: This was a single-centre, prospective cohort study in subjects without OSA (n=20), with untreated OSA (n=33), or with treated OSA (n=21). OSA diagnosis was verified using type III (in-home) polysomnography. Subjects received a stepped-dose remifentanil infusion (target effect-site concentrations of 0.5, 1, 2, 3, 4 ng ml-1). Primary outcome was miosis (pupil area fractional change), the most sensitive opioid effect. Secondary outcomes were ventilatory rate, end-expired CO2, sedation, and thermal analgesia. RESULTS: There were no differences in miosis between untreated OSA subjects (mean=0.51, 95% confidence interval [CI] 0.41-0.61) and subjects without OSA (mean=0.49, 95% CI 0.36-0.62) (mean difference=0.02, 95% CI -0.18 to 0.22); between treated OSA subjects (mean=0.56, 95% CI 0.43-0.68) and subjects without OSA (difference=0.07, 95% CI -0.16 to 0.29); or between untreated OSA and treated OSA (difference=-0.05, 95% CI -0.25 to 0.16). There were no significant differences between subjects without OSA, untreated OSA, and treated OSA in ventilatory rate, end-expired CO2, sedation, or thermal analgesia responses to remifentanil. There was no relationship between OSA severity and magnitude of opioid effects. CONCLUSIONS: Neither obstructive sleep apnoea nor obstructive sleep apnoea treatment affected sensitivity to the miotic, sedative, analgesic, or respiratory depressant effects of the opioid remifentanil in awake adults. These results challenge conventional notions of opioid effects in obstructive sleep apnoea. CLINICAL TRIAL REGISTRATION: NCT02898792 (clinicaltrials.gov).

Methadone pharmacogenetics in vitro and in vivo: Metabolism by CYP2B6 polymorphic variants and genetic variability in paediatric disposition.

AIMS: Methadone metabolism and clearance are determined principally by polymorphic cytochrome P4502B6 (CYP2B6). Some CYP2B6 allelic variants affect methadone metabolism in vitro and disposition in vivo. We assessed methadone metabolism by CYP2B6 minor variants in vitro. We also assessed the influence of CYP2B6 variants, and P450 oxidoreductase (POR) and CYP2C19 variants, on methadone clearance in surgical patients in vivo. METHODS: CYP2B6 and P450 oxidoreductase variants were coexpressed with cytochrome b5 . The metabolism of methadone racemate and enantiomers was measured at therapeutic concentrations and intrinsic clearances were determined. Adolescents receiving methadone for surgery were genotyped for CYP2B6, CYP2C19 and POR, and methadone clearance and metabolite formation clearance were determined. RESULTS: In vitro, CYP2B6.4 was more active than wild-type CYP2B6.1. CYPs 2B6.5, 2B6.6, 2B6.7, 2B6.9, 2B6.17, 2B6.19 and 2B6.26 were less active. CYPs 2B6.16 and 2B6.18 were inactive. CYP2B6.1 expressed with POR variants POR.28, POR.5 and P228L had lower rates of methadone metabolism than wild-type reductase. In vivo, methadone clinical clearance decreased linearly with the number of CYP2B6 slow metabolizer alleles, but was not different in CYP2C19 slow or rapid metabolizer phenotypes, or in carriers of the POR*28 allele. CONCLUSIONS: Several CYP2B6 and POR variants were slow metabolizers of methadone in vitro. Polymorphisms in CYP2B6, but not CYP2C19 or P450 reductase, affected methadone clearance in vivo. CYP2B6 polymorphisms 516G>T and 983T>C code for canonical loss of function variants and should be assessed when considering genetic influences on clinical methadone disposition. These complementary translational in vitro and in vivo results inform on pharmacogenetic variability affecting methadone disposition in patients.

The Current State of Combined Pediatric Anesthesiology-Critical Care Practice: A Survey of Dual-Trained Practitioners in the United States.

BACKGROUND: Combined practice in pediatric anesthesiology (PA) and pediatric critical care medicine (PCCM) was historically common but has declined markedly with time. The reasons for this temporal shift are unclear, but existing evidence suggests that length of training is a barrier to contemporary trainees. Among current practitioners, restriction in dual-specialty practice also occurs, for reasons that are unknown at present. We sought to describe the demographics of this population, investigate their perceptions about the field, and consider factors that lead to attrition. METHODS: We conducted a cross-sectional, observational study of physicians in the United States with a combined practice in PA and PCCM. The survey was distributed electronically and anonymously to the distribution list of the Pediatric Anesthesia Leadership Council (PALC) of the Society for Pediatric Anesthesia (SPA), directing the recipients to forward the link to their faculty meeting our inclusion criteria. Attending-level respondents (n = 62) completed an anonymous, 40-question multidomain survey. RESULTS: Forty-seven men and 15 women, with a median age of 51, completed the survey. Major leadership positions are held by 44%, and 55% are externally funded investigators. A minority (26%) have given up one or both specialties, citing time constraints and politics as the dominant reasons. Duration of training was cited as the major barrier to entry by 77%. Increasing age and faculty rank and lack of a comparably trained institutional colleague were associated with attrition from dual-specialty practice. The majority (88%) reported that they would do it all again. CONCLUSIONS: The current cohort of pediatric anesthesiologist-intensivists in the United States is a small but accomplished group of physicians. Efforts to train, recruit, and retain such providers must address systematic barriers to completion of the requisite training and continued practice.

Opioid Sensitivity in Children with and without Obstructive Sleep Apnea.

BACKGROUND: Opioids are a mainstay of perioperative analgesia. Opioid use in children with obstructive sleep apnea is challenging because of assumptions for increased opioid sensitivity and assumed risk for opioid-induced respiratory depression compared to children without obstructive sleep apnea. These assumptions have not been rigorously tested. This investigation tested the hypothesis that children with obstructive sleep apnea have an increased pharmacodynamic sensitivity to the miotic and respiratory depressant effects of the prototypic µ-opioid agonist remifentanil. METHODS: Children (8 to 14 yr) with or without obstructive sleep apnea were administered a 15-min, fixed-rate remifentanil infusion (0.05, 0.1, or 0.15 µg · kg · min). Each dose group had five patients with and five without obstructive sleep apnea. Plasma remifentanil concentrations were measured by tandem liquid chromatography mass spectrometry. Remifentanil effects were measured via miosis, respiratory rate, and end-expired carbon dioxide. Remifentanil pharmacodynamics (miosis vs. plasma concentration) were compared in children with or without obstructive sleep apnea. RESULTS: Remifentanil administration resulted in miosis in both non-obstructive sleep apnea and obstructive sleep apnea patients. No differences in the relationship between remifentanil concentration and miosis were seen between the two groups at any of the doses administered. The administered dose of remifentanil did not affect respiratory rate or end-expired carbon dioxide in either group. CONCLUSIONS: No differences in the remifentanil concentration-miosis relation were seen in children with or without obstructive sleep apnea. The dose and duration of remifentanil administered did not alter ventilatory parameters in either group.

Simulation and the diagnostic process: a pilot study of trauma and rapid response teams.

BACKGROUND: Simulation is frequently used to recreate many of the crises encountered in patient care settings. Teams learn to manage these crises in an environment that maximizes their learning experiences and eliminates the potential for patient harm. By designing simulation scenarios that include conditions associated with diagnostic errors, teams can experience how their decisions can lead to errors. The purpose of this study was to assess how trauma teams (TrT) and pediatric rapid response teams (RRT) managed scenarios that included a diagnostic error. METHODS: We developed four scenarios that would require TrT and pediatric RRT to manage an error in diagnosis. The two trauma scenarios (spinal cord injury and tracheobronchial tear) were designed to not respond to the heuristic management approach frequently used in trauma settings. The two pediatric scenarios (foreign body aspiration and coarctation of the aorta) had an incorrect diagnosis on admission. Two raters independently scored the scenarios using a rating system based on how teams managed the diagnostic process (search, establish and confirm a new diagnosis and initiate therapy based on the new diagnosis). RESULTS: Twenty-one TrT and 17 pediatric rapid response managed 51 scenarios. All of the teams questioned the initial diagnosis. The teams were able to establish and confirm a new diagnosis in 49% of the scenarios (25 of 51). Only 23 (45%) teams changed their management of the patient based on the new diagnosis. CONCLUSIONS: Simulation can be used to recreate conditions that engage teams in the diagnostic process. In contrast to most instruction about diagnostic error, teams learn through realistic experiences and receive timely feedback about their decision-making skills. Based on the findings in this pilot study, the majority of teams would benefit from an education intervention designed to improve their diagnostic skills.