Hypoxemia and pulmonary hypertension in patients with concomitant restrictive ventilatory defect and sleep apnea: the overlap syndrome.

BACKGROUND: To investigate the severity of hypoxemia and prevalence of pulmonary hypertension (PHTN) in patients with the overlap syndrome (OS) of restrictive ventilatory defect (RVD) and sleep apnea (SA). METHODS: Patients referred for both sleep test and spirometry for suspected SA and ventilatory disorders were recruited prospectively from January 2019 to January 2020. SA was determined by an apnea-hypopnea index ≥ 5/h; average oxygen saturation during sleep (meanSaO2) and percentage of total sleep time with saturation < 90% (T90) were calculated. RVD was diagnosed in the presence of forced expiratory volume in the first second/forced vital capacity (FVC) > 0.7 and FVC < 80% predicted value. PHTN was defined by tricuspid regurgitation peak velocity ≥ 3.4 m/s, documented by noninvasive transthoracic echocardiography. RESULTS: Patients with OS had significantly lower meanSaO2 but higher T90 than subjects with isolated SA and isolated RVD. Patients with OS vs. those with isolated SA had higher odds of PHTN in multivariable analysis with age, sex, and body mass index adjusted for (OR 2.96, 95%CI 1.05-8.91, p = 0.040). Patients with meanSaO2 < 92% vs. meanSaO2 ≥ 92% had significantly higher odds of being diagnosed with PHTN (OR 5.40, 95%CI 2.01-15.7, p < 0.001). Similarly, T90 (≥ 4.5% versus < 4.5%) was also independently associated with the prevalence of PHTN (OR 7.21, 95%CI 2.54-23.67, p < 0.001). CONCLUSION: Patients with OS of RVD and SA had severe hypoxemia, which is associated with the prevalence of PHTN. Further investigation is needed to discern whether therapeutic strategies toward OS might mitigate PHTN in this cohort. TRIAL REGISTRATION: Clinical Trial Registration No. ChiCTR1900027294 on 1 October 2019.

Therapeutic value of treating central sleep apnea by adaptive servo-ventilation in patients with heart failure: A systematic review and meta-analysis.

BACKGROUND: Despite the efficacy of adaptive servo-ventilation (ASV) in suppressing central sleep apnea (CSA), its impact on long-term outcomes is debatable. We aim to identify subjects with specific features who might benefit from ASV therapy. METHODS: Randomized clinical trials and comparative observational studies investigating the effects of ASV on cardiovascular (CV) and all-cause mortality and major adverse cardiovascular events (MACEs) in CSA patients were searched from PubMed, EMBASE, Cochrane library and Web of Science. Eligible studies were identified with relative risks (RR) of death and MACEs compared between patients treated by ASV and usual care. RESULTS: A total of eight studies (three randomized controlled trials and five observational studies) including 2208 participants were selected for analysis. All-cause and CV mortality were not significantly reduced by ASV. Patients with nadir nocturnal saturation ≤ 80% (mean value) had lower risk of MACEs by ASV treatment compared with by usual care (RR, 0.18; p < 0.001). Patients with severe heart failure (HF), defined as left ventricular ejection fraction (LVEF) ≤ 33% (mean value), or HF of New York Heart Association (NYHA) classification of III/IV, did not have reduced risk of MACEs post ASV therapy. However, subjects with LVEF > 33% (RR, 0.35; p < 0.001) or NYHA Ⅰ/Ⅱ (RR, 0.35; p < 0.001) had significantly lower risk of MACEs by using ASV than by usual care. CONCLUSIONS: Although ASV appears to not reduce CV and all-cause death for HF patients with extremely low LVEF, those with profound CSA associated hypoxemia or less severe HF still benefit from ASV therapy.