As obesity increases, the frequency of obstructive sleep apnea and obesity hypoventilation syndrome increases also. However, obesity hypoventilation syndrome frequency is not known, as capnography and arterial blood gas analysis are not routinely performed in sleep laboratories. To investigate the frequency and predictors of obesity hypoventilation syndrome in obese subjects. Retrospective clinical study. Obese subjects who had arterial blood gas analysis admitted to the sleep laboratory and polysomnography were retrospectively analyzed. Subjects with restrictive (except obesity) and obstructive pulmonary pathologies were excluded. Demographics, Epworth-Sleepiness-Scale scores, polysomnographic data, arterial blood gas analysis, and spirometric measurements were recorded. Of the 419 subjects, 45.1% had obesity hypoventilation syndrome. Apnea hypopnea index (p<0.001), oxygen desaturation index (p<0.001) and sleep time with SpO₂<90% (p<0.001) were statistically higher in subjects with obesity hypoventilation syndrome compared to subjects with eucapnic obstructive sleep apnea. The nocturnal mean SpO₂ (p<0.001) and lowest SpO₂ (p<0.001) were also statistically lower in subjects with obesity hypoventilation syndrome. Logistic regression analysis showed that the lowest SpO₂, oxygen desaturation index, apnea hypopnea index and sleep time with SpO₂ <90% were related factors for obesity hypoventilation syndrome. Obesity hypoventilation syndrome should be considered when oxygen desaturation index, apnea hypopnea index and sleep time with SpO₂ <90% are high.

The six-minute walk test (6MWT) is widely used to assess functional capacity and prognosis in patients with idiopathic pulmonary fibrosis (IPF). However, studies on oxygen saturation recovery after the 6MWT in patients with IPF are rare. In our study, we investigated the relationship between oxygen saturation recovery time and dyspnea, fatigue, quality of life, prognostic markers and pulmonary hypertension (PH). In this cross-sectional study, IPF patients diagnosed according to current guidelines and followed up in our Interstitial Lung Disease Outpatient Clinic between 2021 and 2022 were included. Demographics, data from spirometry, diffusion capacity measurement, arterial blood gas analysis, transthoracic echocardiography and the 6MWT were recorded. The oxygen saturation recovery time, distance saturation product (DSP), gender-age-physiology (GAP) index and composite physiological index (CPI) scores were calculated. Dyspnea severity was assessed by the modified Medical Research Council (mMRC) and Dyspnoea-12 (D-12) scales, fatigue severity by the Multidimensional Fatigue Inventory (MFI-20) and quality of life by the St George’s Respiratory Questionnaire (SGRQ). Fifty IPF patients (34 men, 16 women, age: 66.8 ± 7.3 years) were included in the study. The mean FVC was 77.8 ± 19.3%, the DLCO was 52.9 ± 17.1%, the 6-minute walk distance (6MWD) was 385.7 ± 90.6 m, the GAP index was 3.5 ± 1.5, and the CPI was 43.7 ± 14.1. Oxygen saturation after the 6MWT reached pretest values at an average of 135.6 ± 73.5 s. The oxygen saturation recovery time was longer in patients with higher GAP index scores (Rs = 0.870, p < 0.001), CPI scores (Rs = 0.906, p < 0.001), desaturation (Rs = 0.801, p < 0.001), FVC%/DLCO% (Rs = 0.432, p = 0.002), sPAP (Rs = 0.492, p = 0.001), TRV (Rs = 0.504, p = 0.001), mMRC (Rs = 0.913, p < 0.001), MFI-20 (Rs = 0.944, p < 0.001), D-12 scale (Rs = 0.915, p < 0.001) and SGRQ scores (Rs = 0.927, p < 0.001); lower FVC (%) (Rs=-0.627, p < 0.001), DLCO (%) (Rs=-0.892, p < 0.001), PaO2 (Rs=-0.779, p < 0.001), DSP (Rs=-0.835, p < 0.001), and 6MWD (Rs=-0.763, p < 0.001). A total of twenty patients (40%) exhibited an increased risk of PH. According to our multiple regression analysis, oxygen saturation recovery time was independently associated with the GAP index (p = 0.036), the lowest oxygen saturation occurring during the 6MWT (p = 0.011) and the SGRQ score (p < 0.001). Our results showed that oxygen saturation recovery time is associated with dyspnea, fatigue, quality of life, increased risk of PH and prognostic markers in IPF. Therefore, we recommend continuous measurement of oxygen saturation after 6MWT until pretest values are reached.

Previous reports from relatively small clinical cohorts have suggested that the clinical presentation of obstructive sleep apnea (OSA) differs between men and women. We aimed to explore sex differences in clinical and polysomnographic features of OSA in a large nationwide registry. Participants from the ongoing Turkish Sleep Apnea Database (TURKAPNE) Study from 34 centers were included in the current analysis. OSA was defined as an apnea-hypopnea index (AHI) ≥5 events/hour and was classified as mild, moderate, and severe according to AHI cut-offs 5, 15, and 30 events/hour, respectively. In all, 7130 patients (2259 women) were included. OSA was observed in 6323 (88.7 %), of whom 70.2 % were male and 29.8 % were female. In the OSA group, women were older (56.7 ± 11.9 vs. 49.5 ± 11.3 years; p < 0.001) and more obese (body mass index 34.3 ± 7.2 vs. 31.4 ± 5.6 kg/m²; p < 0.001) and had lower AHI (29.8 ± 24.1 vs. 36.8 ± 26.2 events/h; p < 0.001) than men. Loud snoring and witnessed apnea were more common in men than in women whereas women were more frequently presented with insomnia, headache, and mood changes. Women had significantly less total sleep time, less sleep efficiency, and longer sleep latency compared with men (p < 0.001 for each). Additionally, comorbid diseases such as diabetes mellitus, hypertension, asthma, psychiatric disorders, hypothyroidism as well as drug use were more common in women than in men independent of age and obesity (p < 0.05 for each). Our results suggest significant sex differences in clinical and polysomnographic features in this nationwide Turkish adult population. Women with OSA have more symptom burden and comorbidities despite having a less severe AHI.

Background: Comorbid insomnia and obstructive sleep apnea (COMISA) is increasingly recognized as a clinically important sleep disorder phenotype with potential cardiometabolic consequences. However, its association with diabetes mellitus (DM) remains insufficiently characterized. Methods: This cross-sectional analysis included 12,715 adults with suspected obstructive sleep apnea (OSA) from the nationwide multicenter TURKAPNE cohort who underwent full-night polysomnography. Insomnia symptoms were assessed using standardized questionnaire items, and OSA was defined as apnea–hypopnea index (AHI) ≥ 5 events/hour. COMISA was defined as the coexistence of insomnia symptoms and OSA. DM was identified based on self-reported physician diagnosis or use of antidiabetic medications. Multivariable logistic regression was performed to evaluate independent variables associated with COMISA. Results: COMISA was present in 3,275 patients (25.7%). DM was significantly more prevalent among patients with COMISA compared with those without COMISA (22.8% vs. 15.4%, p < 0.001). Overall, COMISA was observed in 33.9% of diabetic individuals and 24.1% of non-diabetic individuals. In multivariable analysis adjusted for age, sex, body-mass-index, smoking status, education level, and comorbidities, DM remained independently associated with COMISA (adjusted OR 1.17; 95% CI 1.05–1.31; p = 0.006). Among COMISA patients, those with DM exhibited greater sleep fragmentation and more severe sleep-disordered breathing, including higher AHI (30.0 vs. 24.0 events/h) and oxygen desaturation index (26.0 vs. 20.0 events/h) ( p < 0.001). Conclusions: DM is independently associated with COMISA and with more severe sleep and respiratory disturbances within this phenotype. These findings highlight the need for integrated screening of sleep disorders in individuals with DM. Trial registration: ClinicalTrials gov (NCT02784977).

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