T. Akashiba et al., Nasal continuous positive airway pressure changes blood pressure "non-dippers" to "dippers" in patients with obstructive sleep apnea, SLEEP, 22(7), 1999, pp. 849-853
To evaluate the circadian pattern of blood pressure (BP) and the effects of
nasal continuous positive airway pressure (CPAP) on patients with obstruct
ive sleep apnea (OSA), we examined 24-hour BP in 38 male OSA patients with
and without nasal CPAP. We measured the BP at 30-min intervals during dayti
me (800 to 2200) and nighttime (2200 to 800) hours. A "dipper" was defined
as a patient who showed an average reduction of at least 10 mm Hg systolic
and 5 mm Hg diastolic between daytime and nighttime values. The subjects we
re predominantly "non-dipper" (22 of 38 patients, 58%). Daytime hypertensio
n (>160/95 mm Hg) was present in 11 of 38 patients (4 "dippers" and 7 "non-
dippers"). After nasal CPAP treatment for 3 days, the average BP decreased
significantly during the day and night in all subjects (p<0.05). Fifteen of
22 subjects who were "non-dippers" before treatment reversed to become "di
ppers." And daytime hypertension was detected in only 5 of these patients d
uring nasal CPAP treatment (4 "dippers" and 1 "non-dipper"). These results
showed that the "non-dipper" status was common in patients with OSA, and th
at nasal CPAP restored the normal circadian "dipper" pattern. We suggest th
at nasal CPAP may contribute to an improved prognosis in patients with OSA
because of a reduction in cardiovascular risk factors in "non-dipper" with
severe OSA.