[Diagnosis of the function of respiratory control in patients with obstructive sleep apnea syndrome]

Twenty-five patients with OSAS were investigated and compared with an age-matched control group of 20 healthy volunteers. The ventilatory responses to pure oxygen administration, active hyperventilation, progressive hyperoxic hypercapnia and progressive isocapnic hypoxia were studied in all subjects.

Hypoxic ventilatory response in OSAS patients was significantly diminished as compared with the control group. Hypercapnic ventilatory response, decrease in ventilation due to chemoreceptor inactivation during oxygen respiration and after hyperventilation did not differ in the two groups. The diminished response to hypoxia in OSAS patients was correlated with the increased respiration-synchronous changes in nasal resistance. Our data seem to suggest that in OSAS patients the diminished responsiveness to hypoxia may increase the likelihood of nocturnal apnea. A decrease in hypoxic inspiratory drive appears to be one mechanism initiating upper airway occlusion.