Obstructive sleep apnea and depression

There are high rates of depression in people with obstructive sleep apnea (OSA) in both community and clinical populations. A large community study reported a rate of 17% and reports for sleep clinic samples range between 21% and 41%. A large cohort study found OSA to be a risk factor for depression, but we are unaware of any longitudinal study of the reverse association. However correlations have not generally been found in smaller studies. Several possible causal mechanisms linking OSA and depression have been proposed but not established. Patients who have depression as well as OSA appear worse off than those with OSA only, and depressive symptoms persist in at least some patients in short term studies of treatment for OSA. Direct treatment of depression in OSA might improve acceptance of therapy, reduce sleepiness and fatigue and improve quality of life, but intervention trials are required to answer this question

Upper airway function and arousability to ventilatory challenge in slow wave versus stage 2 sleep in obstructive sleep apnoea

UnlabelledPatients with obstructive sleep apnoea (OSA) have reduced event rates during slow wave sleep (SWS) compared with stage 2 sleep. To explore this phenomenon, ventilatory and arousal timing responses to partial and complete airflow obstruction during SWS versus stage 2 sleep were examined.MethodsTen patients, mean+/-SD apnoea-hypopnoea index (AHI) 49.7+/-16.5 events/h with reduced OSA frequency during SWS (SWS AHI 18.9+/-14.0 events/h) slept with an epiglottic pressure catheter and nasal mask/pneumotachograph. Patients underwent rapid continuous positive airway pressure (CPAP) dialdowns to three subtherapeutic levels and brief airway occlusions in random order.ResultsPost-dialdown, there were marked reductions in peak flow and minute ventilation, and progressive increases in inspiratory effort (pConclusionsExcept for a heightened ventilatory drive response during airway occlusion, airway function and ventilatory compensation to ventilatory challenge appear to be similar, but with consistently and substantially delayed arousal responses, in SWS versus stage 2 sleep.Rajeev Ratnavadivel, Daniel Stadler, Samantha Windler, Jana Bradley, Denzil Paul, R Douglas McEvoy, Peter G Catchesid

Marked Reduction in Obstructive Sleep Apnea Severity in Slow Wave Sleep

Introduction: Obstructive sleep apnea (OSA) is widely accepted to improve during slow wave sleep (SWS) compared to lighter stages of NREM sleep. However, supporting data to establish the magnitude and prevalence of this effect is lacking. Consequently, we examined this phenomenon, controlling for posture, in a large group of patients investigated for OSA at an academic clinical sleep service. Methods: A detailed retrospective analysis was conducted on data obtained from each 30-sec epoch of sleep in 253 consecutive full-night diagnostic polysomnography studies performed over a 3-month period. Respiratory and arousal event rates were calculated within each stage of sleep, in the supine and lateral postures, and across the whole night, with OSA patients classified on the basis of an overall apnea-hypopnea index (AHI) ≥ 15 events/h. Central sleep apnea (CSA) patients were defined by a central apnea index ≥ 5/h. Sleep latency and time, and respiratory and arousal event rates in OSA, CSA, and non-OSA patients were compared between sleep stages and postures using linear mixed model analysis. The numbers of patients achieving reduced event rates in SWS and in the lateral posture were also examined. Results: There were 171 patients with OSA, 14 with CSA, and 68 non-OSA patients. OSA patients took significantly longer to achieve slow wave and REM sleep (p < 0.001) than non-OSA patients and had less stage 4 sleep (p = 0.037). There were striking improvements in AHI and arousal index (AI) from stage 1 to 4 NREM sleep (p < 0.001), with intermediate levels in REM sleep. AHI and AI were also markedly reduced in lateral versus supine sleep in all sleep stages (p < 0.001), with an effect size comparable to that of the slow wave sleep effect. The majority of OSA patients achieved low respiratory event rates in SWS. Eighty-two percent of patients achieved an AHI < 15 and 57% < 5 events/hour during stage 4 sleep.Rajeev Ratnavadivel, Nuy Chau, Daniel Stadler, Aeneas Yeo, R. Doug McEvoy, Peter G. Catchesid

Physician decision making and clinical outcomes with laboratory polysomnography or limited-channel sleep studies for obstructive sleep apnea: a randomized trial

Background: The clinical utility of limited-channel sleep studies (which are increasingly conducted at home) versus laboratory polysomnography (PSG) for diagnosing obstructive sleep apnea (OSA) is unclear. Objective: To compare patient outcomes after PSG versus limited-channel studies. Design: Multicenter, randomized, noninferiority study. (Australian New Zealand Clinical Trials Registry: ACTRN12611000926932). Setting: 7 academic sleep centers. Participants: Patients (n = 406) aged 25 to 80 years with suspected OSA. Intervention: Sleep study information disclosed to sleep physicians comprised level 1 (L1) PSG data (n = 135); level 3 (L3), which included airflow, thoracoabdominal bands, body position, electrocardiography, and oxygen saturation (n = 136); or level 4 (L4), which included oxygen saturation and heart rate (n = 135). Measurements: The primary outcome was change in Functional Outcomes of Sleep Questionnaire (FOSQ) score at 4 months. Secondary outcomes included the Epworth Sleepiness Scale (ESS), the Sleep Apnea Symptoms Questionnaire (SASQ), continuous positive airway pressure (CPAP) compliance, and physician decision making. results: Change in FOSQ score was not inferior for L3 (mean difference [MD], 0.01 [95% CI, -0.47 to 0.49; P = 0.96]) or L4 (MD, -0.46 [CI, -0.94 to 0.02; P = 0.058]) versus L1 (noninferiority margin [NIM], -1.0). Compared with L1, change in ESS score was not inferior for L3 (MD, 0.08 [CI, -0.98 to 1.13; P = 0.89]) but was inconclusive for L4 (MD, 1.30 [CI, 0.26 to 2.35; P = 0.015]) (NIM, 2.0). For L4 versus L1, there was less improvement in SASQ score (-17.8 vs. -24.7; P = 0.018), less CPAP use (4.5 vs. 5.3 hours per night; P = 0.04), and lower physician diagnostic confidence (P = 0.003). Limitation: Limited-channel studies were simulated by extracting laboratory PSG data and were not done in the home. Conclusion: The results support manually scored L3 testing in routine practice. Poorer outcomes with L4 testing may relate, in part, to reduced physician confidence. Primary Funding Source: National Health and Medical Research Council and Repat Foundation.Ching Li Chai-Coetzer, Nick A. Antic, Garun S. Hamilton, Nigel McArdle, Keith Wong, Brendon J. Yee, Aeneas Yeo, Rajeev Ratnavadivel, Matthew T. Naughton, Teanau Roebuck, Richard Woodman and R. Doug McEvo