Inspiratory effort sensation to added resistive loading in patients with obstructive sleep apnea

Study objectives: Repeated episodes of upper-airway occlusion are the main characteristics of patients with obstructive sleep apnea (OSA) during sleep . It has been reported that an impairment in the sensation of detection and a depression of ventilatory compensation to added load could be observed i n such patients. In this study, we examined patients with OSA to evaluate t he inspiratory effort sensation (IES), ventilation, and mouth occlusion pre ssures during added resistive loading while awake and to determine whether they can be reversed by nasal continuous positive airway pressure (CPAP) tr eatment. Design: A hospital-based case-control study. Setting: A sleep laboratory of a medical unit in Japan. Subjects: Seventeen patients with moderate to severe OSA and 10 control sub jects were included in this study. Measurements: All patients with OSA had undergone standard nocturnal polyso mnography. Patients with OSA and control subjects were evaluated for IES me asured by a modified Borg score, ventilation, and mouth occlusion pressure during control and inspiratory resistive loaded breathing. These tests were repeated in all patients with OSA after 2 weeks of nasal CPAP treatment. Results: IES to inspiratory resistive loading was lower in patients with OS A than in control subjects. There were no differences in ventilation and mo uth occlusion pressure between patients and control subjects during loaded breathing. After 2 weeks of nasal CPAP, the decreased IES was increased in patients with OSA. Conclusion: In patients with OSA, the decreased IES to inspiratory resistiv e loaded breathing is reversible with nasal CPAP. This could be one additio nal benefit of nasal CPAP in the treatment of OSA.