The significance and outcome of continuous positive airway pressure-related central sleep apnea during split-night sleep studies.

OBJECTIVE

To determine whether central sleep apnea (CSA) occurring during continuous positive airway pressure (CPAP) titration in patients with obstructive sleep apnea (OSA) reflects subclinical congestive heart failure (CHF), and whether these events will improve with CPAP therapy.

DESIGN

Cross-sectional analysis of patients with suspected sleep-related breathing disorders referred for split-night polysomnography

PATIENTS AND METHODS

Forty-two OSA patients with and without CPAP-related CSA were analyzed. All CSA patients (n = 21) and control subjects (n = 21) underwent echocardiography, pulmonary function testing, and arterial blood gas (ABG) analysis. Repeat polysomnography with CPAP was performed 2 to 3 months after adequate CPAP therapy in CSA group patients.

RESULTS

Demographic, Epworth sleepiness scale, pulmonary function test, ABG, and baseline diagnostic polysomnography findings were similar in both groups. There was no difference in the prevalence of subclinical left ventricular systolic dysfunction in the CSA group vs the control group. CSA patients had decreased sleep efficiency (SE), increased sleep stage 1 percentage, sleep stages shift, wake time after sleep onset (WASO), and total arousals compared to control subjects. Twelve of 14 patients (92%) in the CSA group demonstrated complete or near-complete resolution of CSA events on follow-up polysomnography and showed improvement in SE, WASO, and total arousals compared to their baseline study.

CONCLUSIONS

CSA events occurring during CPAP titration are transient and self-limited. They may be precipitated by the sleep fragmentation associated with initial CPAP titration and are not associated with an increased prevalence of occult CHF compared to OSA patients without CPAP-related CSA.