RESPIRATION IN NREM AND REM-SLEEP AFTER UPPER AIRWAY SURGERY FOR OBSTRUCTIVE SLEEP-APNEA

To verify whether upper airway surgery in obstructive sleep apnoea syn drome affects differently respiration in NREM and REM sleep, 22 patien ts were studied by polysomnography before and three months after surgi cal treatment. On the average, treatment improved respiration during b oth deep states, but no significant interaction was found between slee p state and effect of surgical treatment. According to the response to treatment, three groups of patients were identified: the first group (N = 6), with an improvement in apnoea-hypopnoea index (AHI), percenta ge of sleep time spent in apnoea and hypopnoea (time in AH) and mean o xyhaemoglobin saturation (SaO(2)) in both NREM and REM sleep; the seco nd group (N = 5), with an improvement in AHI only in NREM sleep, assoc iated with improvement in mean SaO(2) in both sleep states; the third group (N = 11), without any improvement in AHI and time in AH, either associated (N = 5) or not (N = 6) with an improvement in mean SaO(2) i n both sleep states. An increase in the percentage of hypopnoeas out o f the total AHI after treatment could partly account for the apparent discrepancy between AHI and mean SaO(2) behaviour in the subjects of t he second group, but not in the patients of the third group who improv ed their mean SaO(2), Mixed apnoeas occurred before surgery in six sub jects; they remained numerous after surgery only in two subjects who d id not show any SaO(2) improvement, In conclusion, the degree of impro vement in respiration after upper airway surgery was similar in every patient in NREM and REM sleep.