Effects of nasal continuous positive airway pressure on awake ventilatory responses to hypoxia and hypercapnia in patients with obstructive sleep apnea.

TUN, Y., HIDA, W., OKABE, S., KIKUCHI, Y., KUROSAWA, H., TABATA, M. and SHIRATO, H. Effects of Nasal Continuous Positive Airway Pressure on Awake Ventilatory Responses to Hypoxia and Hypercapnia in Patients with Obstructive Sleep Apnea. Tohoku J. Exp. Med., 2000, 190 (2), 157-168 - This study was aimed to examine the short- and long-term effects of nasal continuous positive airway pressure (CPAP) on the chemosensitivity to hypoxia and hypercapnia in the patients with obstructive sleep apnea (OSA). Awake ventilatory responses to hypoxia and hypercapnia mere examined in 28 patients (3 female) with moderate to severe OSA. All these tests mere examined before and after 2 weeks of nasal CPAP. In 10 patients these tests mere repeated after 3-6 months of nasal CPAP. All were also tested for spirometry and arterial blood gas analysis. Patients were middle-aged (48.9+/-9.9 years) and their mean apnea-hypopnea index mas 58.3+/- 20.4/hour. After 2 week of nasal CPAP, PaO2 significantly increased (77.7+/-11.8 vs. 84.6+/-9.8 mmHg) and PaCO2 significantly decreased (44.9+/-3.8 vs. 42.3+/-3.7 mmHg). The ventilatory response to hypoxia significantly decreased (0.80+/-0.51 vs. 0.61+/-0.51 liter/min/%) whereas the ventilatory response to hypercapnia significantly increased after 2 weeks (1.47+/-0.73 vs. 1.80+/-0.76 liter/min/mmHg). Similar findings mere also observed after 3-6 months of nasal CPAP in 10 OSA patients. Nasal CPAP treatment can alter the ventilatory responses in patients with OSA. - ventilatory responses; nasal continuous positive airway pressure; obstructive sleep apnea (C) 2000 Tohoku University Medical Press.