Study objectives: Continuous positive airway pressure
(CPAP) therapy has become the treatment of choice for obstructive sleep
apnea (OSA). However, the efficacy of CPAP therapy has not been
evaluated against a suitable control. We investigated the effectiveness
of CPAP therapy in improving sleep quality in patients with OSA. We
hypothesized that CPAP improves sleep quality.
Patients: Forty-eight CPAP-naive OSA patients were
evaluated. None were receiving antihypertensive medications, and none
had major medical illnesses.
Design: Patients were
randomized to receive either CPAP or placebo CPAP (CPAP at an
ineffective pressure) for 7 days in a double-blind fashion. Forty-one
patients completed the protocol. Sleep quality variables, arousals,
sleep arterial oxygen saturation (Sao2), and
respiratory disturbance index (RDI) were assessed at baseline, after 1
day of treatment, and after 7 days of treatment. Repeated measures
analysis of variance was used to evaluate the effects of treatment,
time, and the interaction of the two.
expected, CPAP lowered RDI and number of arousals, and increased
Sao2 over time (p = 0.001). Contrary to
expectations, both CPAP and placebo CPAP had comparable effects on
sleep quality as assessed by sleep architecture, sleep efficiency,
total sleep time, and wake after sleep onset time.
Conclusions: This study confirms the effectiveness of CPAP
in lowering the number of arousals and the RDI, and in raising
Sao2. However, our data suggest that short-term
CPAP is no different than placebo in improving sleep architecture.
Further evaluation of the effectiveness of CPAP using a suitable
placebo CPAP in prospective randomized studies is