Exercise capacity remains supernormal, though mildly reduced in middle-aged military personnel with Moderate to Severe Obstructive Sleep Apnea.

INTRODUCTION: The relationship between moderate to severe OSA and exercise capacity remains unclear. Prior studies showing a reduction in VO2 max in this population have mostly involved middle-aged, overweight patients. We aimed to study this relationship in a similarly aged population of military personnel with previously undiagnosed moderate to severe OSA. METHODS: We studied late-career male military personnel who underwent CPET and polysomnography (PSG). Patients were categorized either into an OSA group (apnea-hypopnea index (AHI) ≥ 15 events/h) or a control group (AHI < 15 events/h). VO2 max was compared between groups. RESULTS: 170 male military personnel met criteria for the study. Mean AHI was 29.0/h in the OSA group (n = 58) versus 7.4/h in the controls (n = 112) while SpO2 nadir was slightly lower (86.0% vs. 89.0%). Patients were of similar age (53.1 vs. 53.7 years), and BMI was slightly higher in the OSA group (27.5 kg/m2 vs. 26.3 kg/m2). Percent-predicted VO2 max was supernormal in both groups, though it was comparatively lower in the OSA group (117% vs. 125%; p < 0.001). CONCLUSIONS: Military personnel with moderate to severe OSA were able to achieve supernormal VO2 max values, yet had an 8% decrement in exercise capacity compared to controls. These findings suggest that OSA without significant hypoxemia may not significantly influence exercise capacity. It remains likely that the effects of untreated OSA on exercise capacity are complex and are affected by several variables including BMI, degree of associated hypoxemia, and regularity of exercise. Statistically lower VO2 max noted in this study may suggest that untreated OSA in less fit populations may lead to significant decrements in exercise capacity.

OSA and cardiorespiratory fitness: a review.

The effects of untreated obstructive sleep apnea (OSA) on cardiopulmonary function remain unclear. Cardiorespiratory fitness (CRF), commonly reflected by VO2 max measured during cardiopulmonary exercise testing, has gained popularity in evaluating numerous cardiopulmonary conditions and may provide a novel means of identifying OSA patients with the most clinically significant disease. This emerging testing modality provides simultaneous assessment of respiratory and cardiovascular function with results helping uncover evidence of evolving pathology in either organ system. In this review, we highlight the current state of the literature in regard to OSA and CRF with a specific focus on changes in cardiovascular function that have been previously noted. While OSA does not appear to limit respiratory function during exercise, studies seem to suggest an abnormal cardiovascular exercise response in this population including decreased cardiac output, a blunted heart rate response (ie, chronotropic incompetence), and exaggerated blood pressure response. Surprisingly, despite these observed changes in the cardiovascular response to exercise, results involving VO2 max in OSA remain inconclusive. This is reflected by VO2 max studies involving middle-aged OSA patients showing both normal and reduced CRF. As prior studies have not extensively characterized oxygen desaturation burden, we propose that reductions in VO2 max may exist in OSA patients with only the most significant disease (as reflected by nocturnal hypoxia). Further characterizing this relationship remains important as some research suggests that positive airway pressure therapy or aerobic exercise may improve CRF in patients with OSA. In conclusion, while it likely that severe OSA, via an abnormal cardiovascular response to exercise, is associated with decreased CRF, further study is clearly warranted to include determining if OSA with decreased CRF is associated with increased morbidity or mortality. CITATION: Powell TA, Mysliwiec V, Brock MS, Morris MJ. OSA and cardiorespiratory fitness: a review. J Clin Sleep Med. 2022;18(1):279-288.

The Effects of a Digital Mental Health Intervention in Adults With Cardiovascular Disease Risk Factors: Analysis of Real-World User Data.

BACKGROUND: The American Heart Association has identified poor mental health as a key barrier to healthy behavior change for those with cardiovascular disease (CVD) risk factors such as high blood pressure, high cholesterol, and diabetes. Digital mental health interventions, like those delivered via the internet to computers or smartphones, may provide a scalable solution to improving the mental and physical health of this population. Happify is one such intervention and has demonstrated evidence of efficacy for improving aspects of mental health in both the general population and in users with chronic conditions. OBJECTIVE: The objectives of this analysis of real-world data from Happify users with self-reported CVD risk factors, including high blood pressure and cholesterol, diabetes, and heart disease, were to examine whether these users would report improvements in subjective well-being and anxiety over time (H1) and use of Happify as recommended would be associated with significantly greater improvement in subjective well-being and anxiety over time compared to less-than-recommended usage (H2). METHODS: Data were obtained from existing Happify users who reported the aforementioned CVD risk factors. The sample included 1803 users receiving at least 6 weeks' exposure to Happify (ranging from 42 days to 182 days) who completed at least one activity and two assessments within the app during that time. Subjective well-being was assessed with the Happify Scale, a 9-item measure of positive emotionality and life satisfaction, and anxiety was assessed with the Generalized Anxiety Disorder 2 (GAD-2). To evaluate H1, changes over time in both outcomes were assessed using mixed effects linear regression models, controlling for demographics and usage. For H2, an interaction term was added to the models to assess whether usage as recommended was associated with greater improvement over time. RESULTS: Both hypotheses were supported. For both the Happify scale and GAD-2, the initial multivariable model without an interaction demonstrated an effect for time from baseline, and the addition of the interaction term between time and recommended use was significant as well. CONCLUSIONS: This analysis of real-world data provides preliminary evidence that Happify users with self-reported CVD risk factors including high blood pressure or cholesterol, diabetes, and heart disease experienced improved well-being and anxiety over time and that those who used Happify as recommended experienced greater improvements in these aspects of mental health than those who completed fewer activities. These findings extend previous research, which demonstrated that engagement with Happify as recommended was associated with improved well-being among physically healthy users and in those with chronic conditions, to a new population for whom mental health is especially critical: those at risk of developing CVD.

Burn pit exposure in military personnel: is there an effect on sleep-disordered breathing?

PURPOSE: Exposure to elevated concentrations of respirable particulate matter (< 10 µm) may influence sleep-disordered breathing. Burn pits as utilized by the US military in the Middle East until 2011 produced elevated particle matter concentrations. We seek to determine if subjective exposure to burn pits during deployment affects prevalence or severity of obstructive sleep apnea (OSA) in military personnel. METHODS: As part of a prospective observational study of previously deployed military personnel with exertional dyspnea (n = 145), all patients underwent pulmonary function testing, screening for burn pit exposure, and if warranted by questionnaires, overnight polysomnography. A total of 100 patients completed all testing. For analysis, patients were classified into a burn pit exposure group (45 patients) and a no exposure group (55 patients). Additional analyses were performed on those endorsing burn pit maintenance during deployment (25 patients) and those with > 12 h of daily exposure (17 patients). RESULTS: The prevalence of OSA, defined by apnea-hypopnea index (AHI) > 5/h, was similarly high in both groups (69% vs. 71%, p = 0.83). Surprisingly, the mean AHI was lower in the exposed group (12.8/h vs. 19.7/h, p = 0.04) while nadir of oxygen saturation was similar (87% vs. 86%, p = 0.39). Subgroup analyses revealed similar findings in those who performed burn pit maintenance (prevalence = 80%, p = 0.58; AHI = 14.8, p = 0.16) and those with > 12 h of daily exposure (prevalence = 88%, p = 0.33; AHI = 18.0, p = 0.62). CONCLUSIONS: Subjective burn pit exposure does not appear to influence OSA development in previously deployed military personnel. Given the high rate of OSA in this cohort, continued investigation of deployment exposures which may influence sleep-disordered breathing is recommended.

Trauma Associated Sleep Disorder: Clinical Developments 5 Years After Discovery.

PURPOSE OF REVIEW: We review recent and growing evidence that provides support for a novel parasomnia, trauma associated sleep disorder (TASD). Based on these findings, we further develop the clinical and polysomnographic (PSG) characteristics of TASD. We also address factors that precipitate TASD, develop a differential diagnosis, discuss therapy, and propose future directions for research. RECENT FINDINGS: Nightmares, classically a REM phenomenon, are prevalent and underreported, even in individuals with trauma exposure. When specifically queried, trauma-related nightmares (TRN) are frequently associated with disruptive nocturnal behaviors (DNB), consistent with TASD. Capture of DNB in the lab is rare but ambulatory monitoring reveals dynamic autonomic concomitants associated with disturbed dreaming. TRN may be reported in NREM as well as REM sleep, though associated respiratory events may confound this finding. Further, dream content is more distressing in REM. Therapy for this complex disorder likely requires addressing not only the specific TASD components of TRN and DNB but comorbid sleep disorders. TASD is a unique parasomnia developing after trauma. Trauma-exposed individuals should be specifically asked about their sleep and if they have nightmares with or without DNB. Patients who report TRN warrant in-lab PSG as part of their evaluation.

Moderate to Severe Obstructive Sleep Apnea in Military Personnel Is Not Associated With Decreased Exercise Capacity.

STUDY OBJECTIVES: Studies of older and less active patients with obstructive sleep apnea (OSA) have reported decreased exercise capacity as measured by peak oxygen uptake (VO2 max) during cardiopulmonary exercise testing (CPET). We looked to determine whether VO2 max was decreased in younger patients with OSA who regularly exercise as would be encountered in the military. METHODS: We evaluated military personnel who had undergone pulmonary function testing (PFT), CPET, and polysomnography (PSG) as part of the larger STAMPEDE III study for comprehensive evaluation of exertional dyspnea. For analysis, patients were classified into two groups, the OSA group with an apnea-hypopnea index (AHI) ≥ 15 events/h and a control group with an AHI < 15 events/h. RESULTS: Mean AHI was 32.7 in the OSA group (n = 40) versus 5.8 in the control group (n = 58) with no significant difference in age (40.7 years versus 39.4 years) or body mass index (30.4 kg/m2 versus 29.9 kg/m2). PFT was normal in both groups including diffusing capacity (100.7% versus 96.5%) and FEV1 (89.2% versus 86.2%). VO2 max was not significantly different in the OSA group compared to the control group (101.3% versus 102.8%; P = .60) with both groups having normal exercise capacity. Exercise blood pressure response was normal and peak heart rate trended toward a blunted response in the OSA group (166.0 bpm versus 171.6 bpm, P = .09). CONCLUSIONS: Younger military personnel with moderate to severe OSA do not have decreased exercise capacity. The effect of OSA on exercise tolerance may be influenced by additional factors and is likely too small to be noted in this population. COMMENTARY: A commentary on this article appears in this issue on page 819.

Zolpidem and Eszopiclone Pre-medication for PSG: Effects on Staging, Titration, and Adherence.

Introduction: The non-benzodiazepine sedative hypnotic (NBSH) eszopiclone improves polysomnography (PSG) quality and continuous positive airway pressure (CPAP) adherence. It is unclear whether zolpidem has the same effect and neither NBSH has been studied in populations with milder forms of obstructive sleep apnea. Materials and Methods: We performed a retrospective analysis on patients undergoing level I PSG at our institution. Patients are pre-medicated with NBSHs at the discretion of the sleep physician. We compared PSG/CPAP titration quality and subsequent CPAP adherence for patients receiving NBSHs or no pre-study medication. We adjusted for obstructive sleep apnea pre-test probability (PTP), arousal threshold, and other factors showing differences at baseline. Results: Data on 560 patients were analyzed. Mean age and body mass index were 42.2 ± 10.1 and 28.8 ± 4.5, respectively. Median apnea hypopnea index was 12.9 (6.4-25.3), 100 (18.0%) patients had normal studies, 97 (17.3%) were split, and 457 (81.6%) had a respiratory low-arousal threshold. After adjusting for differences at baseline, neither NBSH was associated with sleep efficiency, wake after sleep onset, or total sleep time on PSG. After adjustment, patients receiving eszopiclone had a higher apnea hypopnea index at the final CPAP pressure (ß = 14.2; 95% confidence intervals (CI) 7.2-21.2; p < 0.001) and were more likely to have an unacceptable titration (odds ratio (OR) = 6.6; 95% CI 2.0-21.0; p = 0.002). When only split-night studies were examined, there were no differences in any adherence variables across or between categories. Conclusions: In a population with predominantly mild obstructive sleep apnea, NBSHs did not improve PSG or CPAP titration quality and did not increase CPAP adherence. There was no difference in effect between eszopiclone and zolpidem.