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Objective This study was designed to assess the sensitivity and specificity of a portable sleep apnea recording device ( ApneaLink ™) using standard polysomnography (PSG) as a reference and to evaluate the possibility of using the ApneaLink ™ as a case selection technique for patients with suspected obstructive sleep apnea (OSA). Materials and methods Fifty patients (mean age 48.7 ± 12.6 years, 32 males) were recruited during a 4-week period. A simultaneous recording of both the standard in-laboratory PSG and an ambulatory level 4 sleep monitor ( ApneaLink ™) was performed during an overnight study for each patient. PSG sleep and respiratory events were scored manually according to standard criteria. ApneaLink ™ data were analyzed either with the automated computerized algorithm provided by the manufacturer following the American Academy of Sleep Medicine standards (default setting DFAL) or The University of British Columbia Hospital sleep laboratory standards (alternative setting, ATAL). The ApneaLink respiratory disturbance indices (RDI), PSG apnea–hypopnea indices (AHI), and PSG oxygen desaturation index (ODI) were compared. Results The mean PSG-AHI was 30.0 ± 25.8 events per hour. The means of DFAL-RDI and ATAL-RDI were 23.8 ± 21.9 events per hour and 29.5 ± 22.2 events per hour, respectively. Intraclass correlation coefficients were 0.958 between PSG-AHI and DFAL-RDI and 0.966 between PSG-AHI and ATAL-RDI. Receiver operator characteristic curves were constructed using a variety of PSG-AHI cutoff values (5, 10, 15, 20, and 30 events per hour). Optimal combinations of sensitivity and specificity for the various cutoffs were 97.7/66.7, 95.0/90.0, 87.5/88.9, 88.0/88.0, and 88.2/93.9, respectively for the default setting. The ApneaLink ™ demonstrated the best agreement with laboratory PSG data at cutoffs of AHI ≥ 10. There were no significant differences among PSG-AHI, DFAL-RDI, and ATAL-RDI when all subjects were considered as one group. ODI at 2%, 3%, and 4% desaturation levels showed significant differences ( p  < 0.05) compared with PSG-AHI, DFAL-RDI, and ATAL-RDI for the entire group. Conclusion The ApneaLink ™ is an ambulatory sleep monitor that can detect OSA and/or hypopnea with acceptable reliability. The screening and diagnostic capability needs to be verified by further evaluation and manual scoring of the ApneaLink ™. It could be a better choice than traditional oximetry in terms of recording respiratory events, although severity may be under- or overestimated.

Objectives The aim of this study is to better understand patients’ perspectives and preferences about treatment with continuous positive airway pressure (CPAP) and oral appliance (OA) devices for obstructive sleep apnea. Methods The current study used qualitative analysis of four focus group sessions with current CPAP and OA users. Twenty-two participants with OSA who currently use either CPAP or OA participated in the sessions at the University of British Columbia. Results Five topics from the focus group sessions were descriptively analyzed using NVivo software: goals and expectations of treatment, benefits of treatment for bed partners, side effects and inconveniences of CPAP, side effects and inconveniences of OA, and factors impacting treatment choice. In order of most to least frequently mentioned, patients expressed six expectations of treatment: improved health, apnea elimination, improved sleep, reduced fatigue, reduced snoring, and bed-partner benefits. The most to least mentioned factors impacting treatment choice were device effectiveness, transportability, embarrassment, and cost. Conclusions This qualitative study showed that many factors impact patients’ experience with their treatment device and that their treatment needs are not only physical but also relate to their lifestyle. This preliminary study provides treatment characteristics and attributes necessary to develop a quantitative questionnaire study, to assist in the selection of therapy, weighing the relative importance of patient and OSA treatment characteristics on treatment preference and adherence. Matching therapy to patient preferences may help identify the most appropriate treatment, and this may achieve greater likelihood of adherence.

Swallowing is an important physiological response that protects the airway. Although aspiration during sleep may cause aspiration pneumonia, the mechanisms responsible have not yet been elucidated. We evaluated the coordination between respiration and swallowing by infusing water into the pharynx of healthy young adults during each sleep stage. Seven normal subjects participated in the study. During polysomnography recordings, to elicit a swallow we injected distilled water into the pharynx during the awake state and each sleep stage through a nasal catheter. We assessed swallow latency, swallow apnea time, the respiratory phase during a swallow, the number of swallows, and coughing. A total number of 79 swallows were recorded. The median swallow latency was significantly higher in stage 2 (10.05 s) and stage 3 (44.17 s) when compared to awake state (4.99 s). The swallow latency in stage 3 showed a very wide interquartile range. In two subjects, the result was predominantly prolonged compared to the other subjects. There was no significant difference in the swallow apnea time between sleep stages. The presence of inspiration after swallowing, repetitive swallowing, and coughing after swallowing was more frequent during sleep than when awake. This study suggests that the coordination between respiration and swallowing as a defense mechanism against aspiration was impaired during sleep. Our results supported physiologically the fact that healthy adult individuals aspirate pharyngeal secretions during sleep.

During sleep, the brain cycles regularly between wakefulness, nonrapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. Nonrapid eye movement sleep is subdivided into four stages: stage I, a transitional stage between wake and sleep; stage II, which makes up most of the sleep period; and stages III and IV, which typically occur in the first half of the night and during which more profound stimulus is required to wake the sleeper. Parasomnias occur when transitions between these stages are blurred (commonly between stages III/IV and the awake state), causing behaviours that lack the complete awareness and mentation associated with wakefulness.1 It is not cost-effective to obtain a polysomnogram for patients with NREM parasomnia, except to exclude other causes of additional sleep instability (e.g., obstructive sleep apnea, periodic limb movement disorder, narcolepsy). Because one of the ICSD diagnostic criteria for REM sleep behaviour disorder requires the demonstration of REM sleep without atonia,1 polysomnography is needed to confirm this diagnosis and to rule out comorbid sleep disorders, such as obstructive sleep apnea or periodic limb movement disorder, which are more prevalent in adults and may need to be a focus of management. Rapid eye movement sleep behaviour disorder is characterized by activity in REM sleep causing injury or sleep disruption. Polysomnography is required to confirm the associated electromyographic abnormalities. In REM sleep behaviour disorder, there is a loss of REM atonia with excessive muscle tone, twitches on electromyography, and movements that often appear to be dream enactment, potentially causing injury to the sleeper or bed partner. Episodes usually occur about once a week, but may be as often as four times nightly over consecutive nights. In contrast to all NREM parasomnias, the sleeper awakens rapidly without confusion and often with good recall of a dream that corresponds with the enacted behaviours that can include talking, laughing, swearing, shouting, reaching, grabbing, flailing, punching, hitting or running.5

Purpose The aims of this study were to determine the frequencies of swallowing and swallowing associated with arousals during sleep in patients with obstructive sleep apnea (OSA) and to determine whether these were associated with the severity of OSA and differed according to the preceding breathing route. Methods Standard audio-video polysomnography including an evaluation of swallowing-related elevation of the thyroid cartilage and breathing route (i.e., nasal or oronasal) was undertaken in an academic sleep laboratory. Fifty-six patients were analyzed (13 non-OSA patients, 17 mild, 10 moderate, and 16 severe OSA). Results The frequency of swallowing per hour of sleep was significantly higher in the severe OSA patients when compared to mild OSA patients (mild OSA, 3.1/h and severe OSA, 8.4/h). This was mainly due to the significantly higher frequency of swallowing associated with a respiratory event-related arousal in the severe OSA patients when compared to non- and mild OSA patients (non-OSA, 0.6/h; mild OSA, 1.0/h; severe OSA, 6.0/h), especially when swallowing was preceded by oronasal breathing (non-OSA, 0.2/h; mild OSA, 0.4/h; severe OSA, 4.2/h). Conclusions Swallowing frequency during sleep can increase with increasing OSA severity in most OSA patients. These events are predominately associated with respiratory event-related arousals and are more frequent when preceded by oronasal breathing. The observed swallowing under high ventilatory needs may compromise the maintenance of the pharynx as a conduit for airflow in OSA patients.

Background Previous, largely uncontrolled studies demonstrated the substantial effects of continuous positive airway pressure ventilation (CPAP) on a variety of physiologic and biochemical markers known to be risk factors for cardiovascular disease in patients with obstructive sleep apnea (OSA). In this pilot crossover study, we assessed (1) the feasibility of using CPAP in a group of minimally symptomatic patients with OSA, assessed through patient compliance and (2) CPAP therapy's effect on biomarkers in these patients. Methods We studied patients with minimal daytime sleepiness who were referred to the University of British Columbia's Hospital Sleep Clinic with suspected OSA and an apnea-hypopnea index (AHI) > 15 events/h. Patients were randomized to either CPAP or no therapy for 4 weeks followed by a washout of 4 weeks, and then a crossover to the other intervention. Fasting morning blood and urine, 24-h blood pressure (BP) measurements, and endothelial function (peak flow-mediated dilation to nitroglycerin-mediated dilation ratio) were assessed before and after each study intervention. Results Nine adult male and four female patients were studied. Mean (SD) age was 55 (7) years, mean AHI = 27.9/h, mean Epworth Sleepiness Score = 6.8 (11/13 had a score < 10), and mean BMI = 31.1 kg/m². Mean compliance with CPAP therapy was 5.53 h/night. Compared to no therapy, potential improvements were observed with CPAP for urinary microalbumin, norepinephrine, and epinephrine to creatinine ratios (decreased by 3.51 mg/mmol, 1.70 nmol/mmol, and 0.95 nmol/mmol, respectively); 24-h BP (systolic decreased by 3.60 mmHg, diastolic by 0.70 mmHg); homeostasis model for insulin resistance score (decreased by 1.11); and endothelial function (increased by 7.4%). However, none of the above differences was significant (p > 0.10). Conclusion 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.

Oral appliances (OAs) have been used to treat obstructive sleep apnea (OSA) patients for decades. However, detailed dental side effects in long-term OA cases analyzed with an accurate three-dimensional (3D) measurement tool have seldom been reported. The purpose of this study is to evaluate dental side effects in five OSA patients, who had used a tongue retaining device (TRD) (with occasional other OA wear) for an average of 6 years and 4 months. The baseline and follow-up orthodontic study models were measured with a newly developed MicroScribe-3DX analysis system. High compliance of TRD wear was confirmed in all cases and different patterns and amounts of dental changes were observed. The most common appliance-induced dental changes included anterior and/or unilateral posterior openbites and reduced anterior overjets. It was hypothesized that there might be two possible mechanisms for the TRD side effects—one is the forward pressure of the tongue upon the anterior dental arch and the other is the lateral pressure of the tongue upon the posterior arch. Considerations to correct the TRD dental side effects should be guided by these different mechanisms of the tongue on the dental arch. Possible solutions to minimize occlusal changes and maximize the benefits for OSA patients are also discussed.

OBJECTIVE: To investigate the effects of the Klearway(TM) appliance on the upper airway in patients with obstructive sleep apnea (OSA) in the supine position. METHODS: Sixteen subjects (12 males and 4 females) were recruited on the basis of baseline polysomnography with a documented Apnea and Hypopnea Index (AHI) >15 per hour. A second overnight sleep study was performed for each subject with the appliance in place. Baseline supine cephalometry was performed for each subject before the initial insertion of the appliance, and follow-up supine cephalometry was undertaken with the appliance in place. RESULTS: The polysomnographic variables improved significantly, and the mean changes in overbite and overjet were 5.15 mm and 6.26 mm after insertion of the Klearway(TM) appliance. The supine sagittal cross-sectional areas of the pharynx and the tongue significantly increased, while the linear distance from the hyoid position to the mandibular plane or the RGN-C3 line significantly decreased after insertion of the appliance. The ratio of the vertical pharyngeal length to the sagittal cross-sectional area of nasopharynx or tongue decreased significantly. When the subjects were evaluated on the basis of the after-insertion AHI, the group with good response (n = 11) was found to be significantly younger than the group with the poor response (n = 5). Similarly, the good responders revealed less prominent chins, larger tongue heights, and an increase in hypopharyngeal sagittal cross-sectional area after insertion of the appliance. There was a significant correlation between the improvement in AHI (%) and the supine middle airway space (r = -0.52, p < 0.05). CONCLUSION: The mechanical effect of the Klearway(TM) appliance on the upper airway and the stabilization of jaw posture may be important determinants of the efficacy of the appliance.