Intermittent hypoxia increases lipid insulin resistance in healthy humans: A randomized crossover trial.

Sympathetic overactivity caused by chronic intermittent hypoxia is a hallmark of obstructive sleep apnea. A high sympathetic tone elicits increases in plasma free fatty acid and insulin. Our objective was to assess the impact of 14 nights of chronic intermittent hypoxia exposure on sympathetic activity, glucose control, lipid profile and subcutaneous fat tissue remodelling in non-obese healthy humans. In this prospective, double-blinded crossover study, 12 healthy subjects were randomized, among them only nine underwent the two phases of exposures of 14 nights chronic intermittent hypoxia versus air. Sympathetic activity was measured by peroneal microneurography (muscle sympathetic nerve activity) before and after each exposure. Fasting glucose, insulin, C-peptide and free fatty acid were assessed at rest and during a multisampling oral glucose tolerance test. We assessed histological remodelling, adrenergic receptors, lipolysis and lipogenesis genes expression and functional changes of the adipose tissue. Two weeks of exposure of chronic intermittent hypoxia versus ambient air significantly increased sympathetic activity (p = 0.04). Muscle sympathetic nerve activity increased from 24.5 [18.9; 26.8] before to 21.7 [13.8; 25.7] after ambient air exposure, and from 20.6 [17.4; 23.9] before to 28.0 [24.4; 31.5] bursts per min after exposure to chronic intermittent hypoxia. After chronic intermittent hypoxia, post-oral glucose tolerance test circulating free fatty acid area under the curve increased (p = 0.05) and free fatty acid sensitivity to insulin decreased (p = 0.028). In adipocyte tissue, intermittent hypoxia increased expression of lipolysis genes (adipocyte triglyceride lipase and hormone-sensitive lipase) and lipogenesis genes (fatty acid synthase; p < 0.05). In this unique experimental setting in healthy humans, chronic intermittent hypoxia induced high sympathetic tone, lipolysis and decreased free fatty acid sensitivity to insulin. This might participate in the trajectory to systemic insulin resistance and diabetes for patients with obstructive sleep apnea.

Epidemiology and complications of anaesthesia in the French centres that participated to NECTARINE: A secondary analysis.

INTRODUCTION: Neonatal and infant anaesthesia are associated with a high risk of perioperative complications. The aim of the current study was to describe those risks in France using the French data from the NECTARINE study. MATERIAL AND METHODS: Data from the French centres that participated to the NECTARINE study were analysed. The primary goal of the study was the description of patients' characteristics, procedures and perioperative management and their comparison with the results of the European NECTARINE study. Secondary outcomes were the description of major perioperative complications and death. RESULTS: Overall, 926 procedures collected in 15 centres (all teaching hospitals) were analysed. Comparison between the French and European NECTARINE cohorts found few differences related to patients' characteristics and procedures. The rate of interventions for critical events (respiratory, haemodynamic, and metabolic) was similar between the two cohorts. Near-infrared spectroscopy monitoring was used in 12% of procedures. Nearly none of the thresholds for these interventions met the published standards. By day 30, complications (respiratory, haemodynamic, metabolic, renal, and liver failure) and death were observed in 14.4% [95% CI 11.6-16.4]% and 1.8% [95% CI 1.1-2.9] of cases, respectively. DISCUSSION: Although the health status of the patients in the French cohort was less severe, procedures, management and postoperative complications and mortality rates were similar to the European cohort. However, thresholds for interventions were often inadequate in both cohorts. Efforts should be undertaken to improve the knowledge and use of new monitoring devices in this population.

Anesthesia and sleep apnea.

Due to its low rate of diagnosis, in the general population over half of those experiencing obstructive sleep apnea (OSA) are unaware that they have the condition. However, any acute medical event may exacerbate OSA and could have serious health consequences. In this context the management of the perioperative period, from anesthesia through the surgery itself and into the postoperative period, is more problematic for patients with sleep disordered breathing than for others. There is prolific literature in this area although large randomized trials are few due to the high sample size needed and possible ethical difficulties of withholding OSA treatment in the perioperative period. In 2014 the American Society of Anesthesiologists published an updated set of recommendations to guide OSA management during the perioperative period. In this present review we provide an overview of the different issues that practitioners face with regard to OSA, from the initial consultation with the anesthesiologist to the extended post-operative period. There is considerable evidence that OSA patients are at high risk of perioperative complications, though the inherent risks from OSA per se and its comorbidities remain difficult to discern. Nevertheless, appropriate screening and management allow clinicians to minimize OSA associated risk.