Abnormal breathing during sleep and chemical control of breathing during wakefulness in patients with sleep apnea syndrome

The possible role of ventilatory control in relation to sleep apnea has not yet been clarified. We investigated the relationship between awake ventilatory drives to hypoxia and hypercapnia and sleep-disordered breathing in 21 subjects with sleep apnea syndrome. The awake hypoxic ventilatory drive, which was evaluated by occlusion pressure responses, was inversely correlated with the magnitude of maximal oxygen desaturation during sleep as well as the ratio of duration with more than 4 and 10% oxygen desaturation to total sleep time. On the other hand, the awake hypercapnic ventilatory drive was not correlated with these parameters of sleep desaturation. Apnea index and duration were not correlated with the degree of hypoxic or hypercapnic ventilatory drive, respectively. Our study concluded that sleep desaturation is better correlated with hypoxic ventilatory drive than with hypercapnic ventilatory drive in patients with sleep apnea syndrome. These results are different from the results obtained in the patients with COPD in our previous study.