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Previous studies based on magnetic resonance imaging (MRI) or computed tomography (CT) have shown that pharyngeal airway diameter during wakefulness is different between healthy controls and patients with a high risk of sleep-disordered breathing (SDB). However, MRI and CT are expensive and not easily accessible. Conversely, ultrasonography is more accessible and is getting more attention as a point-of-care technology to assess physiologic systems, such as the pharynx. Thus, we aimed to evaluate the feasibility of ultrasonography in estimating the pharyngeal airway dimension. To evaluate the pharyngeal airway with ultrasonography, we measured the parasagittal anterior-posterior (PAP) diameter and transverse diameter. For PAP diameter measurements, the transducer probe was placed in a submandibular lateral oblique position, with its superior margin abutting the angle of the left mandible. For the transverse measurement, the ultrasound probe was positioned in a submandibular location, in a near-coronal plane, just above the hyoid bone so that the tongue could be seen in cross-section. The diameter measurements were performed manually by two technicians. The reliability of these measurements was assessed by the intra-class correlation coefficient (ICC). To validate our measurements, we compared the measured PAP diameter with the average pharyngeal airway cross-sectional area from vellum to glottis measured by acoustic pharyngometry. Furthermore, we compared the influence of obesity and SDB in the measured pharyngeal diameters. Eighteen controls and 13 individuals with a high risk of SDB participated in this study. Reliability analysis of the PAP measurements yielded an ICC of 0.97 (95% confidence interval: 0.94-0.98). Furthermore, measured PAP diameters were significantly correlated with the pharyngeal airway cross-sectional area (r = 0.76, p0.01). Moreover, obesity and SDB were associated with decreases in PAP diameter. Our study shows that ultrasonography measurement of the PAP diameter may provide a quantitative assessment of the pharyngeal airway and may be useful for screening of SDB.

Study objective To develop an algorithm for improving apnea hypopnea index (AHI) estimation which includes event by event validation and event duration estimation. The algorithm uses breathing sounds, respiratory related movements and blood oxygen saturation (SaO2). Methods Adults with suspected sleep apnea underwent overnight polysomnography (PSG) at Toronto Rehabilitations Institute. Simultaneously with PSG, breathing sounds and respiratory related movements were recorded over the suprasternal notch using the Patch. The Patch had a microphone and an accelerometer to record respiratory sounds and movement, respectively. First, we calculated the amount of drops in SaO2 from pulse oximeter. Subsequently, energy of breaths and accelerometer were extracted. Features were normalized, weighted, summed and passed through a threshold to estimate PatchAHI. PatchAHI was compared to the AHI obtained from PSG (PSGAHI). Furthermore, performance of event detection was evaluated using F1-score. Moreover, event duration difference between estimated and PSG-based events was compared. Results Data from 69 subjects were investigated. PatchAHI had high correlation with PSGAHI (r2 = 0.88). Considering a diagnostic AHI cut-off of ≥15, sensitivity and specificity were 91.42 ± 11.92% and 89.29 ± 7.62%, respectively. F1-score for individual event detection increased from 0.22 ± 0.10 for AHI≤5 to 0.72 ± 0.09 for AHI >30. Moreover, event duration difference between estimated events and PSG-based events was 5.33 ± 8.17 sec. Conclusion Our proposed algorithm had high accuracy in estimating individual respiratory events during sleep. The algorithm can increase reliability of acoustic methods for diagnosis of sleep apnea at home.

Study objectives Overnight fluid shift from the legs into the neck may contribute to the pathogenesis of snoring and obstructive sleep apnea (OSA). The present study investigates the effects of calf muscle electrical stimulation (ES) on reducing leg fluid accumulation while seated, subsequent rostral fluid shift on lying down, and the impact on snoring and OSA. Methods Sixteen non-obese, normotensive men with OSA participated in the study. On the first study day, participants sat for 150 min receiving either active or sham ES through random allocation, then lied supine for 60 min. While seated and supine, leg and neck fluid volumes were measured using bioelectrical impedance to determine the magnitude of fluid shift. On the night of the study day, participants wore a portable sleep apnea diagnostic device overnight to measure snoring and sleep apnea severity. One week later, participants crossed over to the other study condition. Results Active calf muscle ES reduced leg fluid accumulation by 46% while seated. Upon lying supine, active ES reduced fluid shift out of the legs by 17% and reduced neck fluid accumulation by 31%. This led to a 15% reduction in snoring index, but did not alleviate OSA. Conclusions One session of calf muscle ES was effective at reducing leg fluid accumulation and rostral fluid shift, which led to a modest reduction in the snoring index, but not OSA. Despite this lack of effect of calf muscle ES in attenuating OSA severity, the reduction in the snoring index suggests that it did have an effect, albeit mild, on upper-airway mechanics.

To reduce the spread of the severe acute respiratory syndrome coronavirus 2, many pulmonary function testing (PFT) laboratories have been closed or have significantly reduced their testing capacity. Because these mitigation strategies may be necessary for the next 6 to 18 months to prevent recurrent peaks in disease prevalence, fewer objective measurements of lung function will alter the diagnosis and care of patients with chronic respiratory diseases. PFT, which includes spirometry, lung volume, and diffusion capacity measurement, is essential to the diagnosis and management of patients with asthma, COPD, and other chronic lung conditions. Both traditional and innovative alternatives to conventional testing must now be explored. These may include peak expiratory flow devices, electronic portable spirometers, portable exhaled nitric oxide measurement, airwave oscillometry devices, and novel digital health tools such as smartphone microphone spirometers and mobile health technologies along with integration of machine learning approaches. The adoption of some novel approaches may not merely replace but could improve existing management strategies and alter common diagnostic paradigms. With these options comes important technical, privacy, ethical, financial, and medicolegal barriers that must be addressed. However, the coronavirus disease 19 pandemic also presents a unique opportunity to augment conventional testing by including innovative and emerging approaches to measuring lung function remotely in patients with respiratory disease. The benefits of such an approach have the potential to enhance respiratory care and empower patient self-management well beyond the current global pandemic.

Prolonged sitting may promote leg fluid retention that redistributes to the neck during sleep and contributes to snoring. This could be attenuated by calf activity while sitting. In 16 healthy non-obese subjects we measured leg fluid volume (LFV) below the knees using bioelectrical impedance while sitting for 4h, snoring using a portable BresoDx™ device, and Mallampati grade. Using a double cross-over study design, subjects were randomized to one of two arms and crossed-over one week later: control arm - no calf exercise while sitting; intervention arm - calf contraction against a pedal resistance while sitting. The effects of sitting±calf activity on LFV and snoring were compared. We found that LFV increased by 216±101.0ml (p

Objectives Obstructive sleep apnea (OSA) is highly prevalent in patients with fluid-retaining conditions. Using bioimpedance measurements, previous studies have shown that the greater the amount of fluid redistributed from the legs to the neck overnight, the greater the severity of OSA. Our objective was to investigate factors that predispose the development or worsening of OSA in response to experimental fluid overload. Methods Fifteen normotensive and non-obese adult men with and without OSA underwent polysomnography (PSG) during which normal saline was infused intravenously at a minimal rate to keep the vein open (control) or as a bolus of 22 ml/kg body weight (approximately 2 L) in a random order and crossed over after a week. Results and Conclusions Before and after sleep, neck circumference and bioimpedance were measured to calculate neck resistance, reactance, phase angle, and fluid volume. Subjects who experienced more than a twofold increase in apnea–hypopnea index (AHI) or obstructive AHI from control to intervention and had an AHI>10 during intervention were considered susceptible to the development or worsening of OSA. Baseline neck circumference and phase angle before saline infusion were independently associated with increased susceptibility to developing or worsening OSA in response to saline infusion. In non-obese men, a larger neck circumference and bioimpedance phase angle of the neck, which may be associated with larger pharyngeal tissue content, is associated with increased susceptibility for worsening of OSA in response to fluid overloading.

Background Overnight fluid shift from the legs to the neck may narrow the upper airway and contribute to obstructive sleep apnea (OSA) pathogenesis. We hypothesized that below-the-knee compression stockings will decrease OSA severity in a general OSA population by decreasing daytime leg fluid accumulation and overnight fluid shift and increasing upper-airway size. Methods Patients with OSA (apnea–hypopnea index ≥10) were randomized to wear compression stockings during the daytime or to a control group for 2 weeks. Overnight polysomnography with measurement of leg and neck fluid volumes and upper-airway cross-sectional area before and after sleep was performed at baseline and follow-up. The primary outcome was change in the apnea–hypopnea index. Results Twenty-two patients randomized to compression stockings and 23 to control completed the study. The apnea–hypopnea index decreased significantly more in the compression stockings than in the control group (from 32.4 ± 20.0 to 23.8 ± 15.5 vs. from 31.2 ± 25.0 to 30.3 ± 23.8, p = 0.042), in association with a significantly greater reduction in the overnight decrease in leg fluid volume ( p = 0.028), and a significantly greater increase in morning upper-airway cross-sectional area ( p = 0.006). Overnight change in neck fluid volume was unchanged. Conclusion These observations suggest that in, a general OSA population, below-the-knee compression stockings decrease OSA severity modestly via attenuation of overnight fluid shift and consequent upper-airway dilatation.