Research from JAMA — Effect of Continuous Positive Airway Pressure on the Incidence of Hypertension and Cardiovascular Events in Nonsleepy Patients With Obstructive Sleep Apnea — A Randomized Controlled Trial

Research from JAMA — Effect of CPAP on Blood Pressure in Patients With Obstructive Sleep Apnea and Resistant Hypertension — The HIPARCO Randomized Clinical Trial

To investigate the prevalence and behavior of sleep-related breathing disorders (SRBDs) associated with a first-ever stroke or transient ischemic attack (TIA), we prospectively studied 161 consecutive patients admitted to our stroke unit. Complete neurological assessment was performed to determine parenchymatous and vascular localization of the neurological lesion. Stroke subtype was categorized as TIA, ischemic (IS), or hemorrhagic (HS). A portable respiratory recording (PRR) study was performed within 48–72 h after admission (acute phase), and subsequently after 3 mo (stable phase). During the acute phase, 116 patients (71.4%) had an apnea–hypopnea index (AHI) > 10 events/h and 45 (28%) had an AHI > 30. No relationships were found between sleep-related respiratory events and the topographical parenchymatous location of the neurological lesion or vascular involvement. Cheyne–Stokes breathing (CSB) was observed in 42 cases (26.1%). There were no significant differences in SRBD according to the stroke subtype except for the central apnea index (CAI). During the stable phase a second PRR was performed in 86 patients: 53 of 86 had an AHI > 10 and 17 of 86 had an AHI > 30. The AHI and CAI were significantly lower than those in the acute phase (16.9 ± 13.8 versus 22.4 ± 17.3 and 3.3 ± 7.6 versus 6.2 ± 10.2, respectively) (p < 0.05) while the obstructive apnea index (OAI) remained unchanged. CSB was observed in 6 of 86 patients. The prevalence of SRBD in patients with first-ever stroke or TIA is higher than expected from the available epidemiological data in our country. No correlation was found between neurological location and the presence or type of SRBD. Obstructive events seem to be a condition prior to the neurological disease whereas central events and CSB could be its consequence. Parra O, Arboix A, Bechich S, García-Eroles L, Montserrat JM, López JA, Ballester E, Guerra JM, Sopeña JJ. Time course of sleep-related breathing disorders in first-ever stroke or transient ischemic attack.

Rationale: Continuous positive airway pressure (CPAP) is the current treatment for patients with symptomatic obstructive sleep apnea (OSA). Its use for all subjects with sleep-disordered breathing, regardless of daytime symptoms, is unclear. Objectives: This multicenter controlled trial assesses the effects of 1 year of CPAP treatment on blood pressure (BP) in nonsymptomatic, hypertensive patients with OSA. Methods: We evaluated 359 patients with OSA. Inclusion criteria consisted of an apnea–hypopnea index (AHI) greater than 19 hour−1, an Epworth Sleepiness Scale score less than 11, and one of the following: under antihypertensive treatment or systolic blood pressure greater than 140 or diastolic blood pressure greater than 90 mm Hg. Patients were randomized to CPAP (n = 178) or to conservative treatment (n = 181). BP was evaluated at baseline and at 3, 6, and 12 months of follow-up. Measurements and Main Results: Mean (SD) values were as follows: age, 56 ± 10 years; body mass index (BMI), 32 ± 5 kg · m−2; AHI, 45 ± 20 hour−1; and Epworth Sleepiness Scale score, 7 ± 3. After adjusting for follow-up time, baseline blood pressure values, AHI, time with arterial oxygen saturation less than 90%, and BMI, together with the change in BMI at follow-up, CPAP treatment decreased systolic blood pressure by 1.89 mm Hg (95% confidence interval: −3.90, 0.11 mm Hg; P = 0.0654), and diastolic blood pressure by 2.19 mm Hg (95% confidence interval: −3.46, −0.93 mm Hg; P = 0.0008). The most significant reduction in BP was in patients who used CPAP for more than 5.6 hours per night. CPAP compliance was related to AHI and the decrease in Epworth Sleepiness Scale score. Conclusions: In nonsleepy hypertensive patients with OSA, CPAP treatment for 1 year is associated with a small decrease in BP. This effect is evident only in patients who use CPAP for more than 5.6 hours per night. Clinical trial registered with www.clinicaltrials.gov (NCT00127348).

Rationale: Obstructive sleep apnea (OSA) has been associated with increased cancer mortality, but whether it is also associated with cancer incidence is unknown. Objectives: To investigate whether OSA is associated with increased cancer incidence in a large clinical cohort. Methods: A multicenter, clinical cohort study including consecutive patients investigated for suspected OSA between 2003 and 2007 in seven Spanish teaching hospitals. Apnea-hypopnea index (AHI) and percent nighttime with oxygen saturation less than 90% (TSat90) were used as surrogates of OSA severity, both as continuous variables and categorized by tertiles. Cox proportional hazards regression analyses were used to calculate hazard ratio (HR) and 95% confidence interval (CI) for cancer incidence after adjusting for confounding variables. Measurements and Main Results: A total of 4,910 patients were analyzed (median follow-up, 4.5 yr; interquartile range, 3.4–5.2). Compared with the lower TSat90 category (43 vs. <18.7, 1.66; 95% CI, 1.04–2.64). Conclusions: Increased overnight hypoxia as a surrogate of OSA severity was associated with increased cancer incidence. This association seems to be limited to men and patients younger than 65 years of age.

We assessed whether intermittent hypoxia, which emulates one of the hallmarks of obstructive sleep apnoea (OSA), leads to altered faecal microbiome in a murine model.In vivopartial pressure of oxygen was measured in colonic faeces during intermittent hypoxia in four anesthetised mice. 10 mice were subjected to a pattern of chronic intermittent hypoxia (20 s at 5% O₂and 40 s at room air for 6 h·day⁻¹) for 6 weeks and 10 mice served as normoxic controls. Faecal samples were obtained and microbiome composition was determined by 16S rRNA pyrosequencing and bioinformatic analysis by Quantitative Insights into Microbial Ecology.Intermittent hypoxia exposures translated into hypoxia/re-oxygenation patterns in the faeces proximal to the bowel epithelium (<200 μm). A significant effect of intermittent hypoxia on global microbial community structure was found. Intermittent hypoxia increased the α-diversity (Shannon index, p<0.05) and induced a change in the gut microbiota (ANOSIM analysis of β-diversity, p<0.05). Specifically, intermittent hypoxia-exposed mice showed a higher abundance of Firmicutes and a smaller abundance of Bacteroidetes and Proteobacteria phyla than controls.Faecal microbiota composition and diversity are altered as a result of intermittent hypoxia realistically mimicking OSA, suggesting the possibility that physiological interplays between host and gut microbiota could be deregulated in OSA.