A Comparison of Different Success Definitions in Non-Continuous Positive Airway Pressure Treatment for Obstructive Sleep Apnea Using Cardiopulmonary Coupling

Evolution of adherence and self-reported symptoms over 36 months with mandibular advancement device therapy for obstructive sleep apnea: a retrospective study

STUDY OBJECTIVES

Mandibular advancement devices (MAD) constitute a feasible option for management of mild-to-moderate obstructive sleep apnea (OSA) and in severe cases, when indicated. As a chronic condition, the management of OSA with MAD requires long-term patient adherence to treatment. The aim of the study was to investigate adherence to MAD therapy during a 36-month observation period in relation to changes in self-reported symptoms and objective response to therapy.

METHODS

Retrospective chart review of patients referred to the Orofacial Pain Clinic (University of Kentucky) between 2016 and 2021 for management of OSA with MAD was performed. Based on a posttreatment sleep study with MAD in situ, participants were subdivided into optimal response (> 50% reduction of baseline apnea-hypopnea index) and suboptimal response (< 50% reduction of baseline apnea-hypopnea index) groups. Outcomes included self-reported adherence to MAD use, self-reported OSA symptoms including snoring, apneic episodes, tiredness upon awakening, fatigue, and sleep quality (on a 100-mm numerical rating scale), and daytime sleepiness (0-24 on the Epworth Sleepiness Scale). Intragroup and intergroup differences at different time points over a 36-month observation period were assessed with one-way and repeated-measures analysis of variance.

RESULTS

Of 54 participants included (46.3% female, age 64.4 ± 10.71 years), 30 (55.6%) achieved optimal response and 24 (44.4%) achieved suboptimal response. At baseline, participants with optimal response differed from those with suboptimal response in apnea-hypopnea index (P = .007), snoring (P = .026), and sleep quality (P = .042). Although fluctuating in both groups, no difference was found over time in adherence (7 nights/wk, 7 h/night) and in OSA symptoms (all P > .05).

CONCLUSIONS

Adherence to MAD was maintained over 36 months regardless of fluctuation in self-reported OSA symptoms and effectiveness of MAD therapy.

CITATION

Sangalli L, Yanez-Regonesi F, Moreno-Hay I. Evolution of adherence and self-reported symptoms over 36 months with mandibular advancement device therapy for obstructive sleep apnea: a retrospective study. J Clin Sleep Med. 2024;20(4):487-496.

Cardiopulmonary Coupling

Cardiopulmonary coupling (CPC) is a technique that generates sleep spectrogram by calculating the cross-spectral power and coherence of heart rate variability and respiratory tidal volume fluctuations. There are several forms of CPC in the sleep spectrogram, which may provide information about normal sleep physiology and pathological sleep states. Since CPC can be calculated from any signal recording containing heart rate and respiration information, such as photoplethysmography (PPG) or blood pressure, it can be widely used in various applications, including wearables and non-contact devices. When derived from PPG, an automatic apnea-hypopnea index can be calculated from CPC-oximetry as PPG can be obtained from oximetry alone. CPC-based sleep profiling reveals the effects of stable and unstable sleep on sleep apnea, insomnia, cardiovascular regulation, and metabolic disorders. Here, we introduce, with examples, the current knowledge and understanding of the CPC technique, especially the physiological basis, analytical methods, and its clinical applications.

Cardiopulmonary coupling and serum cardiac biomarkers in obesity hypoventilation syndrome and obstructive sleep apnea with morbid obesity

STUDY OBJECTIVES

The main cause of death in patients with obesity hypoventilation syndrome (OHS) is cardiac rather than respiratory failure. Here, we investigated autonomic-respiratory coupling and serum cardiac biomarkers in patients with OHS and obstructive sleep apnea (OSA) with comparable body mass index (BMI) and apnea-hypopnea index (AHI).

METHODS

Cardiopulmonary coupling (CPC) and cyclic variation of heart rate (CVHR) analysis was performed on the electrocardiogram signal from the overnight polysomnogram. Cardiac serum biomarkers were obtained in patients with OHS and OSA with a BMI > 40kg/m². Samples were obtained at baseline and after 3 months of positive airway pressure (PAP) therapy in both groups.

RESULTS

Patients with OHS (n=15) and OSA (n=36) were recruited. No group differences in CPC, CVHR and serum biomarkers were observed at baseline and after 3 months of PAP therapy. An improvement in several CPC metrics, including the sleep apnea index, unstable sleep (low frequency coupling and elevated low frequency coupling narrow band [e-LFC_NB]) and CVHR were observed in both groups with PAP use. However, distinct differences in response characteristics were noted. e-LFC_NB coupling correlated with highly sensitive troponin (hs-troponin-T, p<0.05) in the combined cohort. Baseline hs-troponin-T inversely correlated with awake oxygen saturation in the OHS group (p<0.05).

CONCLUSIONS

PAP therapy can significantly improve CPC stability in obese patients with OSA or OHS, with key differences. e-LFC_NB may function as a surrogate biomarker for early subclinical cardiac disease. Low awake oxygen saturation could also increase this biomarker in OHS.

CLINICAL TRIAL REGISTRATION

Registry: Australian New Zealand Clinical Trials Registry; Name: Obesity Hypoventilation Syndrome and Neurocognitive Dysfunction; URL: https://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367492; Identifier: ACTRN12615000122550.

Cardiopulmonary Sleep Spectrograms Open a Novel Window Into Sleep Biology-Implications for Health and Disease

The interactions of heart rate variability and respiratory rate and tidal volume fluctuations provide key information about normal and abnormal sleep. A set of metrics can be computed by analysis of coupling and coherence of these signals, cardiopulmonary coupling (CPC). There are several forms of CPC, which may provide information about normal sleep physiology, and pathological sleep states ranging from insomnia to sleep apnea and hypertension. As CPC may be computed from reduced or limited signals such as the electrocardiogram or photoplethysmogram (PPG) vs. full polysomnography, wide application including in wearable and non-contact devices is possible. When computed from PPG, which may be acquired from oximetry alone, an automated apnea hypopnea index derived from CPC-oximetry can be calculated. Sleep profiling using CPC demonstrates the impact of stable and unstable sleep on insomnia (exaggerated variability), hypertension (unstable sleep as risk factor), improved glucose handling (associated with stable sleep), drug effects (benzodiazepines increase sleep stability), sleep apnea phenotypes (obstructive vs. central sleep apnea), sleep fragmentations due to psychiatric disorders (increased unstable sleep in depression).

Cardiopulmonary coupling-derived sleep quality is associated with improvements in blood pressure in patients with obstructive sleep apnea at high-cardiovascular risk

OBJECTIVE

Investigate if changes in objective sleep quality index (SQI) assessed through cardiopulmonary-coupling analysis impacts blood pressure (BP) in patients with obstructive sleep apnea at high-cardiovascular risk.

METHODS

Secondary analysis of ECG and pulse-oximetry-[oxygen saturation (SpO2)] data from the Heart Biomarker Evaluation in Apnea Treatment study, multicenter, controlled trial in patients with cardiovascular disease and moderate-severe obstructive sleep apnea, randomly assigned to intervention of healthy lifestyle and sleep hygiene education (HLSE; control group), continuous positive airway pressure (CPAP) or nocturnal supplemental oxygen (NSO). Participants with good-quality ECG-signal and SpO2-signal (n = 241) were included.

RESULTS

CPAP-therapy significantly improved BP, with net average improvement in mean arterial blood pressure during sleep (MAP) when compared with nocturnal supplemental oxygen-therapy or healthy lifestyle and sleep education-therapy, -3.92 (P = 0.012) and -3.83 (P = 0.016), respectively. When stratified on the basis of baseline-SQI, CPAP-therapy improves 24-h MAP -3.02 (P = 0.030) and MAP -5.00 (P = 0.001), in patients with compromised baseline-SQI (SQI < 55). Stratifying the cohort based on changes in SQI during the study period (SQI-SQI), controlling for sex, age over 60, apnea-hypopnea index, SpO2 less than 80%, baseline BP and cardiovascular disease, significant differences are observed comparing the groups that Improved-SQI (SQI < 55, SQI ≥ 55) and Declined-SQI (SQI ≥ 55, SQI < 55) in MAP -4.87 (P = 0.046) and mean diastolic blood pressure (MDP) -4.42 (P = 0.026) as well as MAP -6.36 (P = 0.015), mean systolic blood pressure wake (MSP) -7.80 (P = 0.048) and MDP -5.64 (P = 0.009), respectively. Improved SQI reflects the magnitude of positive effect on BP which is reached mostly through initiation of CPAP-therapy.

CONCLUSION

Cardiopulmonary coupling-derived sleep quality impacted 24-h MAP and MDP, as well as BP during wake, in patients participating in the Heart Biomarker Evaluation in Apnea Treatment-study.

Can improvements in sleep quality positively affect serum adiponectin-levels in patients with obstructive sleep apnea?

BACKGROUND

Assess if changes in sleep quality (Sleep Quality Index, SQI) based on cardiopulmonary coupling-analysis (CPC) impacts serum adiponectin-levels in patients with cardiovascular disease (CVD).

METHODS

Secondary analysis of electrocardiogram (ECG) data from the Heart Biomarker Evaluation in Apnea Treatment study (HeartBEAT), a multicenter, controlled trial in patients with CVD and moderate-severe sleep apnea, randomly assigned to intervention of Continuous Positive Airway Pressure (CPAP), Nocturnal Supplemental Oxygen (NSO) or Healthy Lifestyle and Sleep Hygiene Education (HLSE; control group). Participants with good-quality ECG-signal (n = 241) were included.

RESULTS

Improving CPC-sleep quality was associated with net average improvements in serum adiponectin-levels 2.69 μg/ml (p = 0.005) irrespective of therapy initiated. After controlling for confounders, a unit increase in SQI was associated with increase in serum adiponectin-levels 0.071 μg/ml (p = 0.012) and decrease in insulin-levels 0.197 μIU/ml (p = 0.0018). Similarly, a percentage point increase in sleep apnea indicator (SAI) was associated with decrease in serum adiponectin-levels of 0.071 μg/ml (p = 0.017) and increase in insulin-levels of 0.218 μIU/ml (p = 0.020). A percentage point increase in CPC-sleep fragmentation (eLFC_BB) had a predicted increase in glucose-levels 0.371 mg/dl (p = 0.009) and insulin-levels 0.284 μIU/ml (p = 0.010). In patients receiving CPAP-therapy, a difference in serum adiponictin levels of 3.82 μg/ml (p = 0.025) is observed comparing patients in which SQI-improved to patients that SQI-declined during the study period. The difference is mostly due to a decrease in serum adiponectin levels in patients that decline in SQI (-3.20 μg/ml).

CONCLUSION

Improvements in sleep quality were associated with higher serum adiponectin-levels, and improved measures of glycemic metabolism which may have beneficial effects on metabolic syndrome and cardiovascular health.

CLINICAL TRIAL REGISTRATION NAME AND NUMBER

The Heart Biomarker Evaluation in Apnea Treatment (HeartBEAT) study is registered at https://clinicaltrials.gov/ct2/show/NCT01086800.

Management of obstructive sleep apnea in children with achondroplasia: Outcomes of surgical interventions

INTRODUCTION

Children with achondroplasia are predisposed to obstructive sleep apnea (OSA), however little is known regarding surgical interventions and outcomes for this condition. The aim of this study was to evaluate the severity of OSA in children with achondroplasia and report outcomes of surgical interventions using polysomnography (PSG) parameters.

METHODS

Retrospective chart review of children with achondroplasia with documented OSA from 2002 to 2018 that had pre- and post-operative PSG results. Additional data extracted included age, gender, and type of surgical interventions. The primary outcome was change in postoperative obstructive apnea hypopnea index (OAHI).

RESULTS

Twenty-two children with achondroplasia were identified that underwent formal PSG before and after confirmed OSA. The median age was 12 months (range 4 days-15.3 years, IQR 2 years) at time of initial PSG evaluation. The majority (72.7%) of patients had severe OSA with a median preoperative OAHI of 14.25 (IQR 9.4). The most common surgical intervention was adenotonsillectomy (n = 15). Multilevel surgical intervention was required in 9 (41.0%) patients. Post-operatively, 16 (72.7%) children experienced a reduction in OAHI, of which four (18.2%) had complete OSA resolution. OAHI scores increased in six (27.3%) children. Patients with the most severe OSA at baseline had greater improvements in post-operative OAHI (P < 0.01). Neither type nor number of surgical interventions was associated with improved outcomes (P = 0.51, P = 0.89 respectively).

CONCLUSIONS

Treatment of OSA in children with achondroplasia remains challenging. Although reduction of OAHI is possible, caregivers should be counseled about the likelihood of persistent OSA and the potential for multilevel airway surgery.

Effectiveness of sleep surgery versus a mandibular advancement device for obstructive sleep apnea in terms of nocturnal cardiac autonomic activity

PURPOSE

Sleep surgery and mandibular advancement devices (MAD) are treatments for obstructive sleep apnea (OSA), but their comparative efficacy remains unclear. We compared their efficacy using various parameters.

METHODS

Subjects treated for OSA with sleep surgery or MAD (n = 30/group)-matched for sex, body mass index (BMI), and baseline apnea-hypopnea index (AHI)-were enrolled. The efficacy of these treatments according to polysomnographic parameters, sleep quality questionnaires, and heart rate variability (HRV) time- and frequency-domain parameters were compared between pre-treatment and 3-month post-treatment.

RESULTS

Polysomnographic and sleep quality questionnaire parameters improved significantly in both groups. In time-domain HRV analysis, average normal-to-normal intervals increased significantly in the surgery (942.2 ± 140.8 to 994.6 ± 143.1, P = 0.008) and MAD (901.1 ± 131.7 to 953.7 ± 123.1, P = 0.002) groups. Low frequency (LF) decreased significantly in the surgery group (P = 0.012); high frequency (HF) remained unchanged in both groups. The LF/HF ratio decreased in both groups (2.9 ± 1.8 to 2.3 ± 1.7, P = 0.017, vs. 3.0 ± 1.8 to 2.4 ± 1.4, P = 0.025). Normalized high frequency increased significantly in both groups (31.0 ± 13.2 to 36.8 ± 13.7, P = 0.009, vs. 29.1 ± 10.7 to 33.7 ± 12.5, P = 0.024), in contrast to normalized low frequency. However, no HRV parameter changes differed significantly between the groups after adjusting for age, BMI, and AHI.

CONCLUSION

Sleep surgery and MAD are equally effective treatments for OSA according to cardiac autonomic activity.

Electrocardiogram-based sleep analysis for sleep apnea screening and diagnosis

PURPOSE

Despite the increasing number of research studies of cardiopulmonary coupling (CPC) analysis, an electrocardiogram-based technique, the use of CPC in underserved population remains underexplored. This study aimed to first evaluate the reliability of CPC analysis for the detection of obstructive sleep apnea (OSA) by comparing with polysomnography (PSG)-derived sleep outcomes.

METHODS

Two hundred five PSG data (149 males, age 46.8 ± 12.8 years) were used for the evaluation of CPC regarding the detection of OSA. Automated CPC analyses were based on ECG signals only. Respiratory event index (REI) derived from CPC and apnea-hypopnea index (AHI) derived from PSG were compared for agreement tests.

RESULTS

CPC-REI positively correlated with PSG-AHI (r = 0.851, p < 0.001). After adjusting for age and gender, CPC-REI and PSG-AHI were still significantly correlated (r = 0.840, p < 0.001). The overall results of sensitivity and specificity of CPC-REI were good.

CONCLUSION

Compared with the gold standard PSG, CPC approach yielded acceptable results among OSA patients. ECG recording can be used for the screening or diagnosis of OSA in the general population.

Efficacy and tolerability of a custom-made Narval mandibular repositioning device for the treatment of obstructive sleep apnea: ORCADES study 2-year follow-up data

OBJECTIVE/BACKGROUND

Mandibular repositioning device (MRD) therapy is an alternative to continuous positive airway pressure (CPAP). The Orkney Complex Disease Study-ORCADES study is assessing the long-term efficacy and tolerability of MRD therapy in obstructive sleep apnoea syndrome (OSAS); two-year follow-up data are presented.

PATIENTS/METHODS

OSAS patients who refused or were noncompliant with CPAP were fitted with a custom-made computer-aided design/computer-aided manufacturing (CAD/CAM) bi-block MRD (ResMed, Narval CC™); mandibular advancement was individually titrated. Sleep and respiratory parameters were determined at baseline, 3-6 months, and two years. The primary endpoint was treatment success (percentage of patients achieving a ≥50% reduction in the apnoea-hypopnoea index [AHI]).

RESULTS

Of 315 enrolled patients, 237 remained on MRD treatment at two years, and 197 had follow-up data. The treatment success rate at two years was 67%; AHI <5/h, <10/h and <15/h was achieved in 30%, 56% and 72% of patients, respectively. On multivariate analysis, ≥50% decrease in AHI at 3-6 months and absence of nocturia at 3-6 months were significant predictors of MRD treatment continuation. Adverse events were generally mild, and the majority occurred in the first year of treatment.

CONCLUSIONS

Two years' treatment with an MRD was effective and well tolerated in patients with mild to severe OSAS who refused or were intolerant of CPAP.

Insomnia symptoms in primary care: A prospective study focusing on prevalence of undiagnosed co-morbid sleep disordered breathing

OBJECTIVE

To determine prevalence of comorbid undiagnosed sleep disordered breathing (SDB) in chronic insomnia patients, using two complementary methods, one standard and one novel.

METHODS

Using prospective design, adult patients diagnosed with chronic insomnia, treated with prescription pharmacological agents for >3 months without prior objective sleep evaluation or diagnosis of SDB were invited to participate. All patients recorded their sleep for two consecutive nights using level 3 home-sleep-apnea-test (HSAT) device to derive Respiratory Event Index (REI) for OSA diagnosis. The electrocardiogram-signal (ECG) recorded by the same device was analyzed using FDA cleared medical software, Cardiopulmonary Coupling (CPC) to quantify sleep time and identify sleep-quality and pathology.

RESULTS

Of 110 chronic insomnia patients who volunteered between May 2017 and June 2018, 88% were women. Prevalence of moderate-severe SDB (REI > 15) was 25% based on REI-scoring. Surrogate markers of moderate-severe SDB detected by the novel method identified prevalence of 33%, with negative predictive value 96%, reclassifying 10 individuals that HSAT diagnosed with mild SDB with more advanced disease state. Agreement between the methods is 88%.

CONCLUSION

High prevalence and overlap in symptoms between insomnia and SDB warrants objective testing when evaluating sleep complaints before therapy is initiated. Diagnostic caution is even more importantly warranted for female patients presenting insomnia sleep complaints, as SDB may not be initially considered as a biological symptom driver. CPC-analysis can complement standard HSAT or serve as a standalone option to evaluate sleep complaints in individuals presenting insomnia symptoms before therapy is initiated.

CLINICAL TRIAL REGISTRY NAME AND NUMBER

Pilot study: Co-occurrence of Insomnia and Sleep Disordered Breathing (SDB) symptoms: Prospective study focusing on chronic insomnia patients treated with pharmacological agents. Approved by the Bioethics Committee on March 7^th, 2017. VSNb: 17- 047- S1/ ST - GRA - 17029 - PDX - SH http://vsn.is/is/content/17-047.

The effect of tongue base suspension with uvulopalato-pharyngoplasty on sleep quality in obstructive sleep apnea

The objective was to investigate whether tongue base suspension with uvulopalatopharyngoplasty (UPPP) is beneficial on polysomnography analysis for sleep quality in patients with obstructive sleep apnea (OSA) anatomically classified as Fujita type III (small tonsils and a bulky tongue base). In the retrospective study, the charts of 36 patients with OSA that underwent tongue base suspension with UPPP from 2012 through 2015 were reviewed. The surgical outcome measured according to Sher’s classification (AHI reduction > 50% and AHI < 20 per hour as success group, otherwise as failure group). The pre- and post-operative sleep quality parameters were evaluated, and the total sleep time changes were evaluated based on electroencephalography study, slow wave sleep, sleep efficiency, rapid eye movement sleep percentile, and Epworth sleep scale scores. Respiratory, the outcomes of polysomnography analysis were then compared between the successful surgery and surgical failure groups during a 1-year follow up. Total arousals and reduced respiratory arousal indices, along with unchanged periodic leg movement and spontaneous electroencephalography arousal indices, were observed in the successful surgery group but not in the surgical failure group. There were 66% resulted in surgical success by this surgery, and 34% as in failure group according to Sher’s criteria. Patient sleep quality was further improved by reducing the respiratory arousal index and increasing the rapid eye movement sleep percentile during the 1-year follow up.

Comparison of success criteria based on long-term symptoms and new-onset hypertension in mandibular advancement device treatment for obstructive sleep apnoea: observational cohort study

OBJECTIVE

To identify adequate criteria to determine the success or failure of mandibular advancement device (MAD) treatment for obstructive sleep apnoea (OSA) based on long-term symptoms and new-onset hypertension.

DESIGN

Observational cohort study.

SETTING

A tertiary care hospital setting in South Korea.

PARTICIPANTS

Patients (age >18 years) who were diagnosed with OSA by a polysomnography (PSG) or Watch peripheral arterial tonometry (PAT), and who had been treated with MAD between January 2007 and December 2014 were enrolled.

PRIMARY AND SECONDARY OUTCOME MEASURES

Patients underwent PSG or Watch PAT twice; before and 3 months after the application of MAD. The patients were categorised into success and failure groups using seven different criteria. MAD compliance, witnessed apnoea and snoring, Epworth Sleepiness Scale score and occurrence of new-onset hypertension were surveyed via telephonic interview to determine the criteria that could identify success and failure of MAD.

RESULTS

A total of 97 patients were included. The mean follow-up duration was 60.5 months, and the mean apnoea-hypopnoea index (AHI) was 35.5/hour. Two of the seven criteria could significantly differentiate the success and failure groups based on long-term symptoms, including (1) AHI<10/hour with MAD and (2) AHI<10/hour and AHI reduction of >50% with MAD. Kaplan-Meier survival analysis showed that one criterion of AHI<15/hour with MAD could differentiate the success and failure groups based on new-onset hypertension (p=0.035). The receiver operating characteristic curve analysis indicated that the cut-off AHI for new-onset hypertension was 16.8/hour (71.4% sensitivity and 75.0% specificity).

CONCLUSION

Our long-term follow-up survey for symptoms and new-onset hypertension suggested that some of the polysomnographic success criteria, that is, AHI<10/hour with MAD, AHI<10/hour and AHI reduction of >50% with MAD and AHI<15/hour with MAD may be useful in distinguishing the success group from failure one. Further prospective longitudinal studies are warranted to validate these criteria.

Evaluation of the success of obstructive sleep apnea surgery using criteria based on long-term symptoms and incident hypertension

OBJECTIVE

To identify appropriate success criteria, based on long-term symptoms and incident hypertension, after surgery for obstructive sleep apnea (OSA).

METHODS

This observational cohort study included 97 adult OSA patients (90 men) who underwent surgical treatment at our tertiary medical center. Subjective symptoms [witnessed sleep apnea and snoring, and Epworth sleepiness scale (ESS) scores] were evaluated through a telephone survey, and incident hypertension was assessed from medical records. The subjects were divided into success and failure groups according to seven different criteria, and data were analyzed to identify the criteria that could significantly differentiate the success from failure groups.

RESULTS

The participants had a mean age of 48.8 ± 11.9 years and a mean preoperative body mass index of 26.5 ± 3.5 kg/m². The mean preoperative and postoperative apnea-hypopnea index (AHI) values were 36.1/h and 19.4/h, respectively. The mean follow-up duration was 77.0 ± 31.1 months. Postoperative witnessed apnea, snoring, and the ESS scores decreased significantly compared to preoperative scores in both the success and failure groups based on most of the seven criteria. Among the seven criteria, success and failure groups based on a postoperative AHI cutoff of 15 or 20/h differed significantly in witnessed apnea, snoring, or ESS scores. Kaplan-Meier survival analysis based on incident hypertension revealed that no criterion could significantly distinguish between the two groups.

CONCLUSIONS

Our results suggest that some of the success criteria analyzed may be more useful in differentiating between success and failure groups after surgery, in terms of long-term improvement of subjective OSA-related symptoms.

Cardiopulmonary coupling spectrogram as an ambulatory clinical biomarker of sleep stability and quality in health, sleep apnea, and insomnia

STUDY OBJECTIVES

Ambulatory tracking of sleep and sleep pathology is rapidly increasing with the introduction of wearable devices. The objective of this study was to evaluate a wearable device which used novel computational analysis of the electrocardiogram (ECG), collected over multiple nights, as a method to track the dynamics of sleep quality in health and disease.

METHODS

This study used the ECG as a primary signal, a wearable device, the M1, and an analysis of cardiopulmonary coupling to estimate sleep quality. The M1 measures trunk movements, the ECG, body position, and snoring vibrations. Data from three groups of patients were analyzed: healthy participants and people with sleep apnea and insomnia, obtained from multiple nights of recording. Analysis focused on summary measures and night-to-night variability, specifically the intraclass coefficient.

RESULTS

Data were collected from 10 healthy participants, 18 people with positive pressure-treated sleep apnea, and 20 people with insomnia, 128, 65, and 121 nights, respectively. In any participant, all nights were consecutive. High-frequency coupling (HFC), the signal biomarker of stable breathing and stable sleep, showed high intraclass coefficients (ICCs) in healthy participants and people with sleep apnea (0.83, 0.89), but only 0.66 in people with insomnia. The only statistically significant difference between weekday and weekend in healthy subjects was HFC duration: 242.8 ± 53.8 vs. 275.8 ± 57.1 minutes (89 vs. 39 total nights), F(1,126) = 9.86, p = .002.

CONCLUSIONS

The M1 and similar wearable devices provide new opportunities to measure sleep in dynamic ways not possible before. These measurements can yield new biological insights and aid clinical management.

The effect of continuous positive airway pressure on cardiopulmonary coupling

PURPOSE

The aim of the study was to investigate cardiopulmonary coupling (CPC) as a tool for evaluating the efficacy of continuous positive airway pressure (CPAP) in the treatment of obstructive sleep apnea (OSA).

METHOD

The medical records of patients who had undergone either standard polysomnography (PSG-only group, n = 62) or split-night CPAP titration (CPAP titration group, n = 115) due to habitual snoring or sleep apnea were analyzed.

RESULT

The apnea-hypopnea index, CPC variables, and sleep stage (%) during the first 2 h of the sleep study did not differ between the PSG-only and CPAP titration groups. A comparison of data collected over the first 2 h and that collected over the rest of the sleep study revealed that high-frequency coupling (HFC) increased, and low-frequency coupling (LFC) and elevated LFC (e-LFC) decreased only for the CPAP titration group, while they did not change for the PSG-only group. The proportions of N1 and N3 stages and arousal index decreased while the proportion of R stage increased for both groups. The proportion of N2 stage and mean O₂ saturation increased only for the CPAP titration group, while they did not change significantly for the PSG-only group. HFC increased while LFC and e-LFC decreased linearly as apnea-hypopnea index decreased for the CPAP titration group.

CONCLUSION

CPC effectively reflects the treatment effect of CPAP when compared with an electroencephalography-based sleep stage assessment.