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 SHI RATO, H. Effects of Nasal Continuous Positive Airway Pressure on Awake Vent ilatory Responses to Hypoxia and Hypercapnia in Patients with Obstructive S leep Apnea. Tohoku J. Exp. Med., 2000, 190 (2), 157-168 - This study was ai med to examine the short- and long-term effects of nasal continuous positiv e airway pressure (CPAP) on the chemosensitivity to hypoxia and hypercapnia in the patients with obstructive sleep apnea (OSA). Awake ventilatory resp onses to hypoxia and hypercapnia mere examined in 28 patients (3 female) wi th 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 mo nths 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 a pnea-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 signif icantly decreased (44.9+/-3.8 vs. 42.3+/-3.7 mmHg). The ventilatory respons e 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 findin gs mere also observed after 3-6 months of nasal CPAP in 10 OSA patients. Na sal CPAP treatment can alter the ventilatory responses in patients with OSA . - ventilatory responses; nasal continuous positive airway pressure; obstr uctive sleep apnea (C) 2000 Tohoku University Medical Press.