Awake abnormalities of control of breathing and of the upper airway. Occurrence in healthy older men with nocturnal disordered breathing

Abstract

We hypothesized that preexisting diminished chemical control of breathing and narrowing of the upper airway are associated with sleep-related disordered breathing (SRDB) in healthy older men. Twenty-six subjects, aged 55 to 70, were studied. An SRDB episode was a decrease in arterial oxygen saturation (SaO2) of at least 4 percent. Some of these episodes occurred while airflow continued (ie, nonapneic episodes), and the rest occurred with apnea. Sixteen subjects had greater than 12 SRDB episodes per hour of sleep (SRDB subjects) and ten subjects had less than 8 episodes per hour (controls). During waking, the mean hypercapnic ventilatory response was lower, and the mean supine nasal airway resistance (SNAR) was higher in SRDB subjects than in control subjects. During waking, 12 of 16 SRDB subjects had one or more respiratory abnormalities: four had an elevated SNAR; four had a reduced hypercapnic response; three had a reduced hypoxic ventilatory response, and two had an abnormal flow-volume curve. Only one of ten control subjects had a respiratory abnormality (an elevated SNAR). Also, the number of SRDB episodes per hour correlated with the SNAR, and the minimum SaO2 during sleep correlated with the magnitude of the hypercapnic response. We conclude that SRDB occurs commonly in otherwise healthy older men with preexisting abnormalities of control of breathing or of the upper airway.