Relationship between airflow limitation in response to upper airway negative pressure during wakefulness and obstructive sleep apnea severity.

PURPOSE: The objective was to determine if alteration in airflow induced by negative pressure (NP) applied to participants' upper airways during wakefulness, is related to obstructive sleep apnea (OSA) severity as determined by the apnea-hypopnea index (AHI). METHODS: Adults 18 years of age or greater were recruited. All participants underwent overnight polysomnography to assess their apnea-hypopnea index (AHI). While awake, participants were twice exposed, orally, to -3 cm H2O of NP for five full breaths. The ratio of the breathing volumes of the last two breaths during NP exposure to the last two breaths prior to NP exposure was deemed the NP ratio (NPR). RESULTS: Eighteen participants were enrolled. A strong relationship between the AHI and the exponentially transformed NPR (ExpNPR) for all participants was observed (R2 = 0.55, p < 0.001). A multivariable model using the independent variable ExpNPR, age, body mass index and sex accounted for 81% of variability in AHI (p = 0.0006). A leave-one-subject-out cross-validation analysis revealed that predicted AHI using the multivariable model, and actual AHI from participants' polysomnograms, were strongly related (R2 = 0.72, p < 0.001). CONCLUSION: We conclude that ExpNPR, was strongly related to the AHI, independently of demographic factors known to be related to the AHI.

Validation of a Manual Negative Pressure Wound Therapy Device (PragmaVAC) for Acute and Chronic Wounds: A Prospective, Randomized, Controlled Trial.

BACKGROUND: Negative pressure wound therapy (NPWT) is an alternative to the standard gauze dressings for wound treatment. Due to limited health resources, poor electrical supply, and high costs, NPWT in resource-constrained settings is inaccessible. In conflict-affected settings, civilian injuries typically involve traumatic wounds or chronic wound infections that affect the extremities. METHODS: PragmaVAC® is a manually operated NPWT device designed to increase accessibility to NPWT without the need of electrical power. We aimed to determine the clinical efficacy of PragmaVAC through a controlled, non-blinded open-label clinical trial in a resource-constrained locality. The endpoint was formation of granulation tissue sufficient for wound closure. RESULTS: Fifty-nine patients qualified for analysis (19 Gauze; 40 PragmaVAC). The mean age of participants was 49.25 years, 55.9% were male, and 42.4% were diabetic. Forty three wounds (72.9%) were acute, 44 wounds (74.6%) were clean-contaminated, and 34 wounds (57.6%) were localized to the lower limb. The average duration of treatment was 15.3 days in PragmaVAC vs 36.5 days in control, p = 0.013. Similarly, PragmaVAC required fewer number of dressing changes 2.7 vs 23.2 times, p < 0.0001, at a lower frequency of dressings 0.22/day vs 0.73/day, in the control group, p < 0.0001. CONCLUSIONS: PragmaVAC is associated with accelerated healing and less frequent requirement of dressing changes. The introduction of a manually operated, low-cost device in resource-constrained settings presents an opportunity to improve wound care outcomes, decrease interventions, and optimize usage of material and human resources.

Relative tidal volume and respiratory airflow estimation using tracheal sound and movement during sleep.

Airflow is the reference signal to assess sleep respiratory disorders, such as sleep apnea. Previous studies estimated airflow using tracheal sounds in short segments with specific airflow rates, while requiring calibration or a few breaths for tuning the relationship between sound energy and airflow. Airflow-sound relationship can change by posture, sleep stage and airflow rate or tidal volume. We investigated the possibility of estimating surrogates of tidal volume without calibration in the adult sleep apnea population using tracheal sounds and movements. Two surrogates of tidal volume: thoracoabdominal range of sum movement and airflow level were estimated. Linear regression was used to estimate thoracoabdominal range of sum movement from sound energy and the range of movements. The sound energy lower envelope was found to correlate with airflow level. The agreement between reference and estimated signals was assessed by repeated-measure correlation analysis. The estimated tidal volumes were used to estimate the airflow signal. Sixty-one participants (30 females, age: 51 ± 16 years, body mass index: 29.5 ± 6.4 kg m-2 , and apnoea-hypopnea index: 20.2 ± 21.2) were included. Reference and estimated thoracoabdominal range of sum movement of whole night data were significantly correlated with the reference signal extracted from polysomnography (r = 0.5 ± 0.06). Similarly, significant correlations (r = 0.3 ± 0.05) were found for airflow level. Significant differences in estimated surrogates of tidal volume were found between normal breathing and apnea/hypopnea. Surrogate of airflow can be extracted from tracheal sounds and movements, which can be used for assessing the severity of sleep apnea and even phenotyping sleep apnea patients based on the estimated airflow shape.

Automatic Respiratory Phase Identification Using Tracheal Sounds and Movements During Sleep.

One of the most important signals to assess respiratory function, especially in patients with sleep apnea, is airflow. A convenient method to estimate airflow is based on analyzing tracheal sounds and movements. However, this method requires accurate identification of respiratory phases. Our goal is to develop an automatic algorithm to analyze tracheal sounds and movements to identify respiratory phases during sleep. Data from adults with suspected sleep apnea who were referred for in-laboratory sleep studies were included. Simultaneously with polysomnography, tracheal sounds and movements were recorded with a small wearable device attached to the suprasternal notch. First, an adaptive detection algorithm was developed to localize the respiratory phases in tracheal sounds. Then, for each phase, a set of morphological features from sound energy and tracheal movement were extracted to classify the localized phases into inspirations or expirations. The average error and time delay of detecting respiratory phases were 7.62% and 181 ms during normal breathing, 8.95% and 194 ms during snoring, and 13.19% and 220 ms during respiratory events, respectively. The average classification accuracy was 83.7% for inspirations and 75.0% for expirations. Respiratory phases were accurately identified from tracheal sounds and movements during sleep.

Toward mitigating pressure injuries: Detecting patient orientation from vertical bed reaction forces.

INTRODUCTION: Prolonged bed rest without repositioning can lead to pressure injuries. However, it can be challenging for caregivers and patients to adhere to repositioning schedules. A device that alerts caregivers when a patient has remained in the same orientation for too long may reduce the incidence and/or severity of pressure injuries. This paper proposes a method to detect a person's orientation in bed using data from load cells placed under the legs of a hospital grade bed. METHODS: Twenty able-bodied individuals were positioned into one of three orientations (supine, left side-lying, or right side-lying) either with no support, a pillow, or a wedge, and the head of the bed either raised or lowered. Breathing pattern characteristics extracted from force data were used to train two machine learning classification systems (Logistic Regression and Feed Forward Neural Network) and then evaluate for their ability to identify each participant's orientation using a leave-one-participant-out cross-validation. RESULTS: The Feed Forward Neural Network yielded the highest orientation prediction accuracy at 94.2%. CONCLUSIONS: The high accuracy of this non-invasive system's ability to a participant's position in bed shows potential for this algorithm to be useful in developing a pressure injury prevention tool.

Portable diagnosis of sleep apnea with the validation of individual event detection.

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.

Long-term effects of cardiac rehabilitation on sleep apnea severity in patients with coronary artery disease.

STUDY OBJECTIVES: Sleep apnea (SA) is prevalent among patients with coronary artery disease (CAD) and increases cardiovascular risk. A previous study showed that 1 month of cardiac rehabilitation (CR) reduced severity of SA in patients with CAD by reducing fluid accumulation in the legs during the day and the amount of fluid shifting rostrally into the neck overnight. The aim of this study was to evaluate whether CR will lead to longer-term attenuation of SA in patients with CAD. METHODS: Fifteen patients with CAD and SA who had participated in a 1-month randomized trial of the effects of exercise training on SA were followed up until they completed 6 months of CR (age: 65 ± 10 years; body mass index: 27.0 ± 3.9 kg/m²; apnea-hypopnea index [AHI]: 39.0 ± 16.7). The AHI was evaluated at baseline by polysomnography and then at 6 months by portable monitoring at home. Cardiorespiratory fitness (VO2peak) was evaluated via a graded cardiopulmonary exercise test at baseline and 6 months later. The 6-month CR program included once weekly, 90-minute, in-facility exercise sessions, and 4 days per week at-home exercise sessions. RESULTS: After 6 months of CR, there was a 54% reduction in the AHI (30.5 ± 15.2 to 14.1 ± 7.5, P < .001). Body mass index remained unchanged, but VO2peak increased by 27% (20.0 ± 6.1 to 26.0 ± 8.9 mL/kg/min, P = .04). CONCLUSIONS: Participation in CR is associated with a significant long-term decrease in the severity of SA. This finding suggests that attenuation of SA by exercise could be a mechanism underlying reduced mortality following participation in CR in patients with CAD and SA. CLINICAL TRIAL REGISTRATION: This study is registered at www.controlled-trials.com with identifier number ISRCTN50108373.

Dissociation between objectively quantified snoring and sleep quality.

BACKGROUND: The impact of simple snoring on sleep structure and sleepiness has not been well described. In several studies, self-reported snoring was associated with increased daytime sleepiness. However, most studies did not distinguish patients with simple snoring from those with coexisting obstructive sleep apnea (OSA) using objective measures. We therefore evaluated the relationship between objectively measured snoring and both sleep structure and daytime sleepiness in patients with no or mild OSA. METHODS: Subjects referred for suspected sleep disorders underwent polysomnography (PSG) during which breath sounds were recorded by a microphone. Those with an apnea-hypopnea index (AHI) <15/h were analyzed. Individual snores were identified by a computer algorithm, from which the snore index (SI) was calculated as the number of snores/h of sleep. Sleep stages and arousals were quantified. Daytime sleepiness was evaluated using the Epworth Sleepiness Scale (ESS) score. RESULTS: 74 (35 males) subjects were included (age, mean ±â€¯SD: 46.4 ±â€¯15.3 years and body mass index: 29.8 ±â€¯7.0 kg/m2). The mean SI was 266 ±â€¯243 snores/h. Subjects were categorized according to their SI into 3 tertiles: SI < 100, between 100-350, and >350. No sleep structure indeces, arousals, or ESS score differed among SI tertiles (p > 0.13). There was no correlation between SI and any of these variables (p > 0.29). In contrast, the AHI was significantly related to frequency of arousals (r = 0.23, p = 0.048). CONCLUSIONS: These findings suggest that simple snoring assessed objectively is not related to indices of sleep structure or subjective sleepiness.

Heart rate variability in pulmonary hypertension with and without sleep apnea.

OBJECTIVES: Our aims were to evaluate HRV in pulmonary hypertension (WHO Group 1 and 4) compared to control subjects, and to assess whether the presence of sleep apnea in those with pulmonary hypertension would be deleterious and cause greater impairment in HRV. METHODS: This retrospective case-control study analyzed electrocardiogram segments obtained from diagnostic polysomnography. RESULTS: Forty-one pulmonary hypertension patients were compared to 41 age, sex and apnea-hypopnea index matched healthy controls. The pulmonary hypertension group had decreased high frequency, very low frequency, low frequency, and percentage of normal R-R intervals that differ by > 50 ms compared to control subjects. Moderate to severe right ventricle dysfunction on echocardiography was a predictor of lower high frequency in pulmonary hypertension patients. CONCLUSIONS: There were no differences in any HRV measures in pulmonary hypertension patients with or without sleep apnea. Impaired HRV was demonstrated in pulmonary hypertension patients however, the presence of sleep apnea did not appear to further reduce vagal modulation.

Heart rate variability in pulmonary hypertension with and without sleep apnea

Objectives: Our aims were to evaluate HRV in pulmonary hypertension (WHO Group 1 and 4) compared to control subjects, and to assess whether the presence of sleep apnea in those with pulmonary hypertension would be deleterious and cause greater impairment in HRV. Methods: This retrospective case-control study analyzed electrocardiogram segments obtained from diagnostic polysomnography. Results: Forty-one pulmonary hypertension patients were compared to 41 age, sex and apnea-hypopnea index matched healthy controls. The pulmonary hypertension group had decreased high frequency, very low frequency, low frequency, and percentage of normal R-R intervals that differ by > 50 ms compared to control subjects. Moderate to severe right ventricle dysfunction on echocardiography was a predictor of lower high frequency in pulmonary hypertension patients. Conclusions: There were no differences in any HRV measures in pulmonary hypertension patients with or without sleep apnea. Impaired HRV was demonstrated in pulmonary hypertension patients however, the presence of sleep apnea did not appear to further reduce vagal modulation.

Relationship of stroke volume to different patterns of Cheyne-Stokes respiration in heart failure.

STUDY OBJECTIVES: In patients with heart failure (HF) and reduced left ventricular ejection fraction (HFrEF), stroke volume (SV) falls during hyperpnea of Cheyne-Stokes respiration with central sleep apnea (CSR-CSA). We have identified two distinct patterns of hyperpnea: positive, in which end-expiratory lung volume (EELV) remains at or above functional residual capacity (FRC), and negative, in which EELV falls below FRC. The increase in expiratory intrathoracic pressure generated by the latter should have effects on the heart analogous to external chest compression. To test the hypotheses that in HFrEF patients, CSR-CSA with the negative pattern has an auto-resuscitation effect such that compared with the positive pattern, it is associated with a smaller fall in SV and a smaller increase in cardiac workload (product of heart rate and systolic blood pressure). METHODS: In 15 consecutive HFrEF patients with CSR-CSA during polysomnography, hemodynamic data derived from digital photoplethysmography during positive and negative hyperpneas were compared. RESULTS: Compared to the positive, negative hyperpneas were accompanied by reductions in the maximum and mean relative fall in SV of 30% (p = 0.002) and 10% (p = 0.031), respectively, and by reductions in the degree of increases in heart rate and rate pressure product during hyperpnea of 46% (p < 0.001) and 13% (p = 0.007), respectively. CONCLUSIONS: Our findings suggest the novel concept that the negative pattern of CSR-CSA may constitute a form of auto-resuscitation that acts as a compensatory mechanism to maintain SV in patients with severe HF.

Objective Relationship Between Sleep Apnea and Frequency of Snoring Assessed by Machine Learning.

STUDY OBJECTIVES: Snoring is perceived to be directly proportional to sleep apnea severity, especially obstructive sleep apnea (OSA), but this notion has not been thoroughly and objectively evaluated, despite its popularity in clinical practice. This might lead to overdiagnosis or underdiagnosis of OSA. The goal of this study is to examine this notion and objectively quantify the relationship between sleep apnea and snoring detected using advanced signal processing algorithms. METHODS: We studied adults referred for polysomnography, from which the apnea-hypopnea index (AHI) was derived. Breath sounds were recorded simultaneously, from which snoring was accurately quantified using acoustic analysis of breath sounds and machine-learning computer algorithms. The snore index (SI) was calculated as the number of snores per hour of sleep. RESULTS: In 235 patients, the mean AHI was 20.2 ± 18.8 and mean SI was 320.2 ± 266.7 events/h. On the one hand, the overall correlation between SI and AHI was weak but significant (r = .32, P < .0001). There was a significant stepwise increase in SI with increasing OSA severity, but with a remarkable overlap in SI among OSA severity categories. On the other hand, SI had weak negative correlation with central AHI (r = -.14, P = .035). SI had modest positive and negative predictive values for OSA (0.63 and 0.62 on average, respectively) and good sensitivity but low specificity (0.91 and 0.31 on average, respectively) attributed to the large number of snorers without OSA. CONCLUSIONS: Snoring on its own is probably of limited usefulness in assessing sleep apnea presence and severity, because of its weak relationship with AHI. Thus, the complaint of snoring should be interpreted with caution to avoid unnecessary referrals for sleep apnea testing. Conversely, clinicians should be aware of the possibility of missing diagnosis of patients with sleep apnea who have minimal snoring.

Effect of calf muscle electrical stimulation on rostral fluid shift, snoring and obstructive sleep apnea.

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.

Sleep Apnea Severity Estimation from Respiratory Related Movements Using Deep Learning.

Sleep apnea is a common chronic respiratory disorder which occurs due to the repetitive complete or partial cessations of breathing during sleep. The gold standard assessment of sleep apnea requires full night polysomnography in a sleep laboratory which is expensive, time consuming, and inconvenient. Hence, there is an urgent need for a convenient, robust and wearable monitoring device for screening of sleep apnea. A simple and convenient accelerometer-based portable system is presented to estimate the severity of sleep apnea by analyzing tracheal movements. Respiratory related movements were recorded over the suprasternal notch using a 3D accelerometer. Twenty-one physiological features (7 features, 3 accelerometer channels) were extracted. Performance of three different deep learning models - convolutional neural network, recurrent neural network, and their combination - were evaluated for estimating the apnea hypopnea index (AHI). The estimated AHI is compared to the gold standard polysomnography. In 3-fold cross-validation experiments with 20 participants (9 female, age=47.8±18.0 years, BMI=30.8±4.8, AHI=22.2±21.8 events/hr), we achieved a correlation coefficient between gold standard and estimated values (r-value = 0.84). The proposed system is an accurate, convenient, and portable device suitable for home sleep apnea screening.

Diagnosis of Obstructive Sleep Apnea during Wakefulness Using Upper Airway Negative Pressure and Machine Learning.

Background and Rational: Obstructive Sleep Apnea (OSA) is a common disorder, affecting almost 10% of adults, but very underdiagnosed. This is largely due to limited access to overnight sleep testing using polysomnography (PSG). Our goal was to distinguish OSA from healthy individual using a simple maneuver during wakefulness in combination with machine learning methods. Methods: Participants have undergone an overnight PSG to determine their ground truth OSA severity. Separately, they were asked to breathe through a nasal mask or a mouth piece through which negative pressure (NP) was applied, during wakefulness. Airflow waveforms were acquired and several features were extracted and used to train various classifiers to predict OSA. Results and Discussion: The performance of each classifier and experimental setup was calculated. The best results were obtained using Random Forest classifier for distinguishing OSA from healthy individuals with a very good area under the curve of 0.80. To the best of our knowledge, this is the first study to deploy machine learning and NP with promising path to diagnose OSA during wakefulness.

Feasibility of Using a Smartwatch to Intensively Monitor Patients With Chronic Obstructive Pulmonary Disease: Prospective Cohort Study.

BACKGROUND: Acute exacerbations of chronic obstructive pulmonary disease (COPD) are associated with accelerated decline in lung function, diminished quality of life, and higher mortality. Proactively monitoring patients for early signs of an exacerbation and treating them early could prevent these outcomes. The emergence of affordable wearable technology allows for nearly continuous monitoring of heart rate and physical activity as well as recording of audio which can detect features such as coughing. These signals may be able to be used with predictive analytics to detect early exacerbations. Prior to full development, however, it is important to determine the feasibility of using wearable devices such as smartwatches to intensively monitor patients with COPD. OBJECTIVE: We conducted a feasibility study to determine if patients with COPD would wear and maintain a smartwatch consistently and whether they would reliably collect and transmit sensor data. METHODS: Patients with COPD were recruited from 3 hospitals and were provided with a smartwatch that recorded audio, heart rate, and accelerations. They were asked to wear and charge it daily for 90 days. They were also asked to complete a daily symptom diary. At the end of the study period, participants were asked what would motivate them to regularly use a wearable for monitoring of their COPD. RESULTS: Of 28 patients enrolled, 16 participants completed the full 90 days. The average age of participants was 68.5 years, and 36% (10/28) were women. Survey, heart rate, and activity data were available for an average of 64.5, 65.1, and 60.2 days respectively. Technical issues caused heart rate and activity data to be unavailable for approximately 13 and 17 days, respectively. Feedback provided by participants indicated that they wanted to actively engage with the smartwatch and receive feedback about their activity, heart rate, and how to better manage their COPD. CONCLUSIONS: Some patients with COPD will wear and maintain smartwatches that passively monitor audio, heart rate, and physical activity, and wearables were able to reliably capture near-continuous patient data. Further work is necessary to increase acceptability and improve the patient experience.

Reproducibility and predictors of the apnea hypopnea index across multiple nights.

BACKGROUND: Attended polysomnography (PSG) is the standard diagnostic test for sleep apnea (SA). However, due to internight variability in SA, a single night PSG may not accurately reflect the true severity of SA. Although internight variability is a well-known phenomenon, its root causes have not been fully elucidated. The objective of this study was to determine factors associated with internight variability in the apnea-hypopnea index (AHI) and its magnitude in the home environment. METHODS: Each participant had a full overnight PSG simultaneous with a validated portable sleep apnea monitoring device (BresoDx®) followed by two overnight home tests using the portable monitor only. Patients were stratified into those with variable AHI and consistent AHI (AHI difference ≥10 or <10 between any 2 nights, respectively). Demographics, sleepiness, sleep test variable, and supine-predominant SA (supine-SA) were examined for any association with variable AHI. RESULTS: Forty patients completed the protocol. The correlation between PSG and simultaneous BresoDx derived AHIs was 93.4%. Inter-class correlation between the three nights' AHIs was 89.2%. Over two-thirds (67.5%) of patients had consistent AHIs across the three nights while 32.5% had variable AHI. AHI variability was significantly associated with supine-SA (p=0.0014) and correlated with first night's AHI (r=0.664, p<0.001). None of the other variable, including BMI, sleepiness, gender, or test duration were associated with internight variability. CONCLUSION: Although portable monitoring was highly reproducible over three nights in the majority of participants, one third had a variable AHI. Supine-SA and high AHI on the first night were predictors of high internight variability.

The effect of continuous positive airway pressure on spectral encephalogram characteristics in stroke patients with obstructive sleep apnea

OBJECTIVES: To evaluate if treatment with continuous positive airway pressure (CPAP) compared to usual care in stroke patients with obstructive sleep apnea (OSA) over one month reduces delta and alpha oscillations on quantitative electroencephalography (EEG) in association with improvements in cognitive or functional outcomes. METHODS: Spectral EEG analysis was performed in patients with subacute stroke and OSA randomized to usual care or CPAP treatment from a previous study. RESULTS: A total of 23 subjects were included. Compared to CPAP (n = 14), those in the control (n = 9) group demonstrated a significant increase in alpha power (p = 0.042). There was no between group differences for delta, theta or beta power. No significant correlation was demonstrated between the change in alpha power and indices of OSA severity or sleepiness. The increase in alpha power did not correlate with improvements in outcomes. CONCLUSION: Contrary to expectations CPAP treatment of OSA did not significantly decrease alpha and delta oscillations in stroke subjects.

The effect of continuous positive airway pressure on spectral encephalogram characteristics in stroke patients with obstructive sleep apnea.

OBJECTIVES: To evaluate if treatment with continuous positive airway pressure (CPAP) compared to usual care in stroke patients with obstructive sleep apnea (OSA) over one month reduces delta and alpha oscillations on quantitative electroencephalography (EEG) in association with improvements in cognitive or functional outcomes. METHODS: Spectral EEG analysis was performed in patients with subacute stroke and OSA randomized to usual care or CPAP treatment from a previous study. RESULTS: A total of 23 subjects were included. Compared to CPAP (n = 14), those in the control (n = 9) group demonstrated a significant increase in alpha power (p = 0.042). There was no between group differences for delta, theta or beta power. No significant correlation was demonstrated between the change in alpha power and indices of OSA severity or sleepiness. The increase in alpha power did not correlate with improvements in outcomes. CONCLUSION: Contrary to expectations CPAP treatment of OSA did not significantly decrease alpha and delta oscillations in stroke subjects.