Chest
Clinical InvestigationsSleep and BreathingDeterminants of Chronic Hypercapnia in Japanese Men With Obstructive Sleep Apnea Syndrome
Section snippets
Materials and Methods
The study cohort consisted of 146 male patients who had received a diagnosis of OSAS based on the results of polysomnography (PSG). Patients with airway obstruction (ie, FEV1/FVC ratio, < 70%) were excluded from this study. All patients gave informed consent for participation. No patients had chronic lung disease or were receiving bronchodilator therapy.
A full night of PSG with continuous recordings of the EEG, electrooculogram, submental electromyogram, ECG, airflow at the nose and mouth (by
Results
The mean age was 48.3 ± 11.3 years, and the mean BMI was 29.6 ± 5.7 kg/m2. The results of pulmonary function tests were normal in all but six of the patients who had restrictive ventilatory abnormalities (ie, percent vital capacity [%VC], < 80%). No patients had evidence of obstructive airway disease (FEV1/FVC ratio, < 70%). The average daytime Pao2 and Paco2 levels were 80.7 ± 9.6 and 44.5 ± 5.3 mm Hg, respectively. The comparisons between hypercapnic and normocapnic patients on baseline
Discussion
We found a relatively high incidence of daytime hypercapnia in patients with severe OSAS (38%). In previous studies,23478910 the prevalence of hypercapnia in patients with OSAS varied from 14 to 57%. However, the number of patients in these previous studies was small. In the largest study, Leech et al7 examined 111 patients with OSAS and found that 41 of 111 patients (36%) had chronic hypercapnia. Although alveolar hypoventilation, hypercapnia, and hypoxemia occur in some patients with chronic
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