閉塞性睡眠時無呼吸症候群における呼吸動態

Abstract

Sixty-two subjects with obstructive sleep apnea syndrome were studied during sleep to characterize the pattern of respiration. Their mean age was 48.4 years (range 20 to 74 years). These patients were compared to a group of 16 age-matched adults who had no respiratory problems. All-night polygraphic recording was performed without the use of any drugs. We examined the intraesophageal pressure, apnea index, mean apnea duration and duty cycle (inspiratory duration divided by the duration of the total respiratory cycle). The severity of sleep dyspnea was classified into three groups depending on the amplitude of intraesophageal pressure; slight (15-19 cmH2O), moderate (20-39cmH2O) and severe (40 cmH2O and over).As the grade of intraesophageal pressure increased, the apnea index increased accordingly. Moreover, there was a prolongation of the average duration of obstructive and mixed apnea. When the patients had severe respiratory disturbance during sleep, the duty cycle of the inspiratory muscles decreased progressively before obstructive apnea started. These findings suggest that obstructive apnea is related to the degree of upper airway stenosis and that the decrease in the duty cycle may be responsible for upper airway occlusion in addition to anatomical abnormality of the soft palate, sinking of the soft palate and base of the tongue and relaxation of the pharyngeal muscles during sleep.