Endothelial dysfunction in the microcirculation of patients with obstructive sleep apnea.

RATIONALE: Obstructive sleep apnea (OSA) is a risk factor for cardiovascular disease. We hypothesized that patients with OSA and no cardiovascular disease have oxidant-related microcirculatory endothelial dysfunction. OBJECTIVES: To evaluate the microcirculation in OSA. METHODS: This study included seven patients with OSA and seven age- and weight-matched control subjects (mean age, 38 yr; mean body mass index, 32.5 kg/m²). All participants were free of cardiovascular risk factors. Participants received measurement of brachial artery flow-mediated dilation and forearm subcutaneous biopsy. Patients underwent repeated tests 12 weeks after treatment. Microcirculatory endothelial cells were isolated, and immunohistochemistry staining for peroxynitrite in the microcirculation was performed. MEASUREMENTS AND MAIN RESULTS: Flow-mediated dilation was lower in patients than in control subjects at baseline (mean ± SEM: 5.7 ± 0.5 vs. 9.5 ± 0.6; P = 0.02) and increased after treatment (5.7-7.3; change, 1.7 ± 0.6; P = 0.04). Microcirculatory peroxynitrite deposit was higher in patients compared with control subjects (44.0 ± 1.6 vs. 21.8 ± 1.9 stain density units; P < 0.001) and decreased after treatment from 44.0 to 30.5 stain density units (change, -13.5 ± 2.9; P = 0.009). In patients, transcription of endothelial nitric oxide synthase decreased from 5.2 to -1.3 after treatment (change, 6.5 ± 2.5; P = 0.05), and transcription of superoxide dismutase1 decreased from -4.0 to -12.3 after treatment (change, -8.3 ± 2.1; P = 0.01). These changes persisted after adjustment for weight and underlying severity of OSA. CONCLUSIONS: This is the first direct evaluation of the microcirculation in OSA. Patients with OSA with low cardiovascular risk status had increased oxidant production in the microcirculation and endothelial dysfunction, both of which improved with treatment. Endothelial nitric oxide synthase transcription decreased with treatment.

Prevalence of obstructive sleep apnea in patients with chronic wounds.

STUDY OBJECTIVES: Chronic non-healing wounds are a major human and economic burden. Obstructive sleep apnea (OSA) is prevalent in patients with obesity, diabetes, aging, and cardiovascular disease, all of which are risk factors for chronic wounds. We hypothesized that OSA would have more prevalence in patients of a wound center than the general middle-aged population. METHODS: Consecutive patients of the Ohio State University Comprehensive Wound Center (CWC) were surveyed with the Berlin and Epworth questionnaires. In the second stage of the protocol, 50 consecutive unselected CWC patients with lower extremity wounds underwent home sleep studies. RESULTS: In 249 patients of the CWC who underwent the survey study, OSA had been previously diagnosed in only 22%. The prevalence of high-risk status based on questionnaires for OSA was 46% (95% CI 40%, 52%). In the 50 patients who underwent home sleep studies, and using an apnea hypopnea index of 15 events per hour, the prevalence of OSA was 57% (95% CI 42%, 71%). There was no difference between the Berlin questionnaire score and weight between patients with OSA and those without. CONCLUSIONS: The prevalence of OSA in patients with chronic wounds exceeds the estimated prevalence of OSA in the general middle aged population. This study identifies a previously unrecognized population with high risk for OSA. Commonly used questionnaires were not sufficiently sensitive for the detection of high risk status for OSA in this patient population.