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Obstructive sleep apnea hypopnea (OSAH) appears to be associated with an increased risk of motor vehicle crashes (MVC). However, its impact on crash patterns and particularly the severity of crashes has not been well described. We sought to determine whether OSAH severity influenced crash severity in patients referred for investigation of suspected sleep-disordered breathing. Objective crash data (including the nature of crashes) for patients with suspected OSAH for the 3 years prior to polysomnography were obtained from provincial insurance records and compared to an age and sex matched control group. Data were obtained for 783 patients with suspected OSAH and 783 matched controls. The patient group was 71% male, with a mean age of 50years, a mean apnea-hypopnea index (AHI) of 22 events/hour and a mean Epworth sleepiness scale score of 10. There were 375 crashes, of which 252 were in patients and 123 in controls in the 3-year period. When compared to controls, patients with mild, moderate, and severe OSAH had an increased rate of MVC with relative risks (95% CI) of 2.6 (1.7, 3.9), 1.9 (1.2, 2.8), and 2.0 (1.4, 3.0) respectively, whereas patients with suspected OSAH and normal polysomnography (AHI 0-5) did not with a relative risk (95% CI) of 1.5 (0.9, 2.5 p =0.21). When we examined the impact of OSAH on MVC associated with personal injury, patients with mild, moderate, and severe OSAH had a substantially increased rate of MVC compared to controls with relative risks of 4.8 (1.8, 12.4), 3.0 (1.3, 7.0), and 4.3 (1.8, 8.9) respectively, whereas patients without OSAH had similar crash rates to control with a relative risk of 0.6 (0.2, 2.5). Very severe MVCs (head-on collisions or those involving pedestrians or cyclists) were rare but 80% of these occurred in OSAH patients (p=0.06).

In this pilot study there were potential improvements in a variety of cardiovascular biomarkers with CPAP. CPAP compliance was reasonably good even though patients were not particularly sleepy. Accordingly, larger randomized controlled trials in this area appear feasible and warranted.

S leep disorders are extremely common and have substantial adverse impacts on both quality of life and mental health. Three of the most common sleep disorders are insomnia, obstructive sleep apnea (OSA), and restless legs syndrome (RLS).Psychiatric disorders such as depression and anxiety are more common in people who have insomnia. Furthermore, chronic insomnia is also a risk factor for the development of psychiatric disorders. 1 OSA is a common respiratory sleep disorder characterized by recurrent upper airway collapse during sleep, leading to recurrent asphyxia and sleep fragmentation. Patients with OSA are at increased risk of having motor vehicle crashes, cardiovascular disease, hypertension, and stroke. 2,3 Furthermore, OSA is an independent risk factor for the development of incident depression. 4 Treatment of OSA leads to substantial improvements in daytime sleepiness, mood, and quality of life. 5,6 RLS is a sensorimotor disorder that has a significant impact on sleep. Characteristic symptoms include the desire to move the limbs associated with paresthesia or dysesthesia, which begin or worsen during periods of inactivity predominately in the

Expiratory pressure relief (C-Flex) technology monitors the patient's airflow during expiration and reduces the pressure in response to the patient. Increased comfort levels associated with C-Flex therapy have potential to improve patient adherence to therapy. The purpose of this study was to assess the combination of autoadjusting CPAP (APAP) and C-Flex in terms of (1) treatment efficacy, and (2) patient preference when compared to standard CPAP. Fifteen patients who had previously undergone formal CPAP titration polysomnography were treated with either one night of the APAP with C-Flex or one night of conventional CPAP, in a crossover trial. Patient satisfaction levels were recorded using visual analog scales (VAS) on the morning after the study. Mean patient age was 50± 12 years, body mass index (BMI) was 36±6 kg/m 2 , baseline AHI was 53±31 events/h, and CPAP Pressure was 11±2 cm/H 2 O. APAP with C-Flex was as effective as CPAP, with no differences detected in sleep latency (17±5 vs 12.3±3 min, p=0.4), or respiratory indices (AHI of 4.2±2 vs 2.4±0.7 events/h, p=0.1). VAS scores (scale 0-10) indicated a trend towards increased patient satisfaction while using APAP with C-Flex (7.9 vs 7.2, p=0.07). 10 patients expressed a preference for APAP with C-Flex (VAS, 0 to10) over standard CPAP (total positive score of 68, mean score of 4.8±4.3). One patient expressed no preference. Four patients expressed a preference for CPAP (total positive score of 13, mean score of 0.9±1.9) (APAP with C-Flex vs standard CPAP, p<0.01 paired t test). APAP with C-Flex eliminates sleep disordered breathing as effectively as standard CPAP. Patients indicated a preference for APAP with C-Flex suggesting a possible advantage in terms of patient adherence for this mode of treatment.

We did not find significant associations between OSA and markers of activated innate immunity (IL-1B, 6, and 8). However, OSA severity was independently associated with serum levels of sVCAM-1 and leptin; these may represent mechanisms involved in the pathogenesis of OSA-related CVD.

These findings suggest that (1) a more substantial or a different pattern of hypoxemia might be necessary to activate systemic inflammation, (2) the system may need to be primed before hypoxic exposure, or (3) increases in inflammatory markers in patients with OSA may be more related to other factors such as obesity or nocturnal arousal.

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