DEVELOPMENT OF NOCTURNAL RESPIRATORY DISTURBANCE IN UNTREATED PATIENTS WITH OBSTRUCTIVE SLEEP-APNEA SYNDROME

Patient histories suggest that obstructive sleep apnea syndrome (OSAS) is a progressive condition. To investigate whether this could be show n in data from sleep recordings, 42 patients with OSAS were retrospect ively studied. All had undergone a screening recording of respiration movements and oximetry at least 6 months (average, 16 months) prior to a diagnostic polysomnogram including these parameters. No treatment w as given in the meantime. In the first recording, mean oxygen desatura tion index (ODI, average number of desaturations of >4 percent per sle eping hour) was 10; periodic, obstructive respiration movements occurr ed during (average) 36 percent of total estimated sleeping time, and m ean nadir SaO2 was 85 percent. In the second recording, mean ODI was 2 1 (significant change, p = 0.0002), periodic respiration time was 61 p ercent, and nadir SaO2 was 80 percent (p = 0.0001, respectively). In 2 6 of 42 patients (62 percent), ODI had increased by >50 percent. Incre ases in ODIs and periodic breathing were significantly correlated to i ncreases in body weight. There were, however, exceptional patients wit h considerable increases in respiratory disturbance despite weight los s. The greatest changes were found in the patients who had the highest apnea indices in the polysomnograms. Early treatment may therefore be justified, since a borderline case may change to severe OSAS in 1 to 2 years' time. Follow-up recordings of untreated patients are importan t.