INFLUENCE OF OBSTRUCTIVE SLEEP-APNEA ON CIRCADIAN BLOOD-PRESSURE PROFILE

A high prevalence of systemic hypertension in obstructive sleep apnoea (OSA) has been described but data on circadian blood pressure (BP) pr ofile are limited and give inconsistent results, The present study exa mines 24-h BP in 106 patients referred because of loud snoring or exce ssive daytime sleepiness in combination with snoring, Patients were cl assified as OSA (n = 62) or habitual snorers (HS) (n = 44), Respirator y disturbance index (RDI) in OSA was 47 +/- 24 vs, 2 +/- 2 in HS. Mean age and body mass index in OSA was significantly higher. BP was measu red non-invasively at 15-min intervals during a 24-h period, Daytime a nd night-time BP was higher in OSA compared to HS, BP night/day ratio in OSA was 0.92 +/- 0.07 vs, 0.86 +/- 0.06 in HS (P < 0.05). To invest igate the influence of variables other than breathing abnormalities du ring sleep on our results we compared BP profiles of 25 OSA and 25 I-I S matched for sex, age and body weight, Again differences in daytime a nd night-time BP and BP night/day ratio were significant. Using a valu e of at least 10% fall in nocturnal BP to describe a regular BP profil e (dipper) 68% of OSA were classified as non-dippers vs, 24% of HS. In fluence of short-term (2-4 days) nCPAP therapy on circadian BP profile was investigated in 34 patients with OSA, Systolic and diastolic noct urnal (but not daytime) BP was significantly reduced, The percentage o f non-dippers was 79% before and 50% after treatment, In conclusion re sults of this study indicate a causal link between OSA and abnormal ci rcadian BP profile.