Key Point

Bilevel positive airway pressure has been associated with an increased frequency of central sleep apnea.

BOSTON—Although bilevel positive airway pressure (BiPAP) helps many patients with sleep-disordered breathing, a recent study has shown that it increases the frequency of central apneas compared to the standard therapy, continuous positive airway pressure (CPAP).¹ That tendency should be taken into consideration when physicians are prescribing BiPAP, study coauthor Douglas C. Johnson, MD, told Pulmonary Reviews.

We began the study after we noticed that BiPAP sometimes worsened central apneas in patients having sleep studies at our institution,” related Dr. Johnson, Director of the Diagnostic Sleep Laboratory at the Spaulding Rehabilitation Hospital in Boston. The worsening was most pronounced in patients with baseline Cheyne-Stokes respiration or periodic respiration but was also quite significant in those who lacked such a respiratory pattern, he observed.

The authors retrospectively evaluated 719 patients who underwent sleep studies during a two-year period. The sleep studies began with a test of tolerance to CPAP while awake; patients were switched to BiPAP if CPAP did not improve hypoxia or caused dyspnea or other respiratory events. Patients also received BiPAP if they had respiratory muscle weakness or if a need for BiPAP had been previously determined.

Ninety-five patients received BiPAP; of these, 80 were also treated with CPAP. At baseline, 14 patients displayed Cheyne-Stokes respiration, 18 exhibited “periodic breathing” (periodic increases and decreases in respiratory effort without central apnea), and 21 had both forms of sleep-disordered breathing. Central apnea alone was found in three patients. The baseline central apnea index was greater than 5 per hour in 23 patients and greater than 10 per hour in 15 patients.

Among patients with baseline Cheyne-Stokes respiration or periodic breathing, Cheyne-Stokes respiration worsened with BiPAP in 48% of cases. When the authors analyzed the combination of Cheyne-Stokes respiration, periodic breathing, and central apnea, 62% of these patients showed worsening when they were placed on BiPAP.

Of the patients without baseline Cheyne-Stokes respiration or periodic breathing, 18% developed Cheyne-Stokes respiration when treated with BiPAP. Thirty-four percent developed Cheyne-Stokes respiration, periodic breathing, or central apnea with BiPAP.

In addition, BiPAP worsened 24% of central apneas in patients who had Cheyne-Stokes respiration and 23% of central apneas in those who did not. With CPAP, those rates were only 11% and 8%, respectively.

When BiPAP was used, a backup rate did not abolish central events, noted the authors. Furthermore, higher pressure differences worsened central events in 28% of patients by reducing Pco2 levels.

Interestingly, central apneas typically improved during REM sleep pre-PAP and with CPAP or BiPAP, which is consistent with ventilatory control during REM sleep being much less dependent on chemoreceptors. However, hypopneas and obstructive apneas usually worsened during REM sleep, during which there is reduced airway muscle tone.

Based on the study findings and the literature, Dr. Johnson recommended CPAP as the first-line treatment for obstructive sleep apnea and Cheyne-Stokes respiration. For patients who cannot tolerate CPAP because of dyspnea, he suggested trying an exhalation pressure relief device before switching the patient to BiPAP.

—Timothy Begany

Reference

1. Johnson KG, Johnson DC. Bilevel positive airway pressure worsens central apneas during sleep. Chest. 2005;128:2141-2150.

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