Observational Study of Pulse Transit Time in Children With Sleep Disordered Breathing

Background: Pulse transit time (PTT) is a non-invasive measure of arousals and respiratory effort for which we aim to identify threshold values that detect sleep disordered breathing (SDB) in children. We also compare the sensitivity and specificity of oximetry with the findings of a multi-channel study. Methods: We performed a cross-sectional observational study of 521 children with SDB admitted for multi-channel sleep studies (pulse oximetry, ECG, video, sound, movement, PTT) in a secondary care centre. PTT data was available in 368 children. Studies were categorised as normal; primary snoring; upper airway resistance syndrome (UARS); obstructive sleep apnoea (OSA), and "abnormal other." Receiver operator characteristic curves were constructed for different PTT (Respiratory swing; Arousal index) thresholds using a random sample of 50% of children studied (training set); calculated thresholds of interest were validated against the other 50% (test set). Study findings were compared with oximetry categories (normal, inconclusive, abnormal) using data (mean and minimum oxygen saturations; oxygen desaturations > 4%) obtained during the study. Results: Respiratory swing of 17.92 ms identified SDB (OSA/UARS) with sensitivity: 0.80 (C.I. 0.62-0.90) and specificity 0.79 (C.I. 0.49-0.87). PTT arousal index of 16.06/ hour identified SDB (OSA/UARS) with sensitivity: 0.85 (95% C.I. 0.67-0.92) and specificity 0.37 (95% C.I. 0.17-0.48). Oximetry identified SDB (OSA) with sensitivity: 0.38 (C.I. 0.31-0.46) and specificity 0.98 (C.I. 0.97-1.00). Conclusions: PTT is more sensitive but less specific than oximetry at detecting SDB in children. The additional use of video and sound enabled detection of SDB in twice as many children as oximetry alone.

Exenatide improves excessive daytime sleepiness and wakefulness in obese patients with type 2 diabetes without obstructive sleep apnoea

We investigate the effects of exenatide on excessive daytime sleepiness (EDS), driving performance and depression score in patients with type 2 diabetes with EDS. Eight obese patients with diabetes but without obstructive sleep apnoea (OSA) participated in a placebo-controlled single-blind study during which multiple wakefulness and sleep latency test, Epworth score, driving performance, depression score, fasting glucose and glycated haemoglobin (HbA1c) levels were assessed at baseline, end of placebo and treatment phase at baseline and after 22 weeks of treatment. Mean (±standard error of the mean) age, body mass index (kg m(2) ) and HbA1c [mmol mol(-1) (%)] of patients at baseline were 50 ± 4.9 years, 37.6 ± 1.1 and 65 ± 19 (8.06 ± 0.41), respectively. When compared to placebo, exenatide treatment was associated with a decrease in both subjective and objective sleepiness, based on the Epworth score reduction and the sleep latency increase assessed by multiple objective sleepiness and sustained attention (OSLER) tests, respectively. Mean sleep latency time (adjusted for change in HbA1c and weight) were 32.1 ± 1.7, 29.1 ± 1.7 and 37.7 ± 1.7, respectively (P = 0.002). Modelling for covariates suggested that improvement in mean sleep latency time is predicted by changes in weight (P = 0.003), but not by changes in HbA1c (P = 0.054). Epworth sleepiness score was reduced significantly (values for placebo versus exenatide: 11.3 ± 1.2 versus 5.7 ± 1.3; P = 0.003). No significant change was noted in the depression score and driving performance. Exenatide is associated with a significant reduction in objective sleepiness in obese patients with type 2 diabetes without OSA, independent of HbA1c levels. These findings could form a basis for further studies to investigate the pathophysiological mechanisms of sleepiness in obese patients with type 2 diabetes.