Abnormalities in autonomic function in obese boys at-risk for insulin resistance and obstructive sleep apnea.

STUDY OBJECTIVES: Current evidence in adults suggests that, independent of obesity, obstructive sleep apnea (OSA) can lead to autonomic dysfunction and impaired glucose metabolism, but these relationships are less clear in children. The purpose of this study was to investigate the associations among OSA, glucose metabolism, and daytime autonomic function in obese pediatric subjects. METHODS: Twenty-three obese boys participated in: overnight polysomnography; a frequently sampled intravenous glucose tolerance test; and recordings of spontaneous cardiorespiratory data in both the supine (baseline) and standing (sympathetic stimulus) postures. RESULTS: Baseline systolic blood pressure and reactivity of low-frequency heart rate variability to postural stress correlated with insulin resistance, increased fasting glucose, and reduced beta-cell function, but not OSA severity. Baroreflex sensitivity reactivity was reduced with sleep fragmentation, but only for subjects with low insulin sensitivity and/or low first-phase insulin response to glucose. CONCLUSIONS: These findings suggest that vascular sympathetic activity impairment is more strongly affected by metabolic dysfunction than by OSA severity, while blunted vagal autonomic function associated with sleep fragmentation in OSA is enhanced when metabolic dysfunction is also present.

Initiation of home mechanical ventilation in children with neuromuscular diseases.

OBJECTIVE: To determine how often home mechanical ventilation (HMV) is instituted electively in children with respiratory failure from neuromuscular diseases and whether there were opportunities to discuss therapeutic options with patients/families before respiratory failure. METHODS: Patients with neuromuscular disease (n = 73) requiring HMV (age, 2 months to 24 years) were studied. Whether HMV was initiated nonelectively because of acute respiratory failure or electively before acute respiratory failure, and opportunities for health care providers to discuss therapeutic options with patients/families before acute respiratory failure (hospitalization with pneumonia, clinic visits for preoperative evaluation, pulmonary function testing [PFT] and/or polysomnography [PSG]) were recorded. RESULTS: HMV was initiated electively in 21% of patients with neuromuscular disease; 69% of the nonelective HMV group had HMV initiated after respiratory failure caused by pneumonia. In the nonelective group, opportunities for discussion of therapeutic options with the patients and families could have occurred before respiratory failure during 111 hospitalizations for pneumonia, 13 preoperative evaluations, 43 abnormal PFTs, and 24 abnormal PSGs. CONCLUSIONS: Most patients with neuromuscular disease had HMV initiated nonelectively after acute respiratory failure caused by pneumonia. Opportunities for discussing the therapeutic options with patients and families before respiratory failure were missed or ineffective.