BOSTON – Adaptive servoventilation is more reliably effective than continuous positive airway pressure is for the prolonged treatment of complex sleep apnea, a study has shown.
Prior studies have shown that the adaptive ventilatory support method, which continuously monitors and analyzes a patient’s breathing pattern and adds variable amounts of inspiratory pressure support to low levels of background expiratory positive airway pressure as needed, is initially more effective than is continuous positive airway pressure (CPAP) in complex sleep apnea patients. But sustained efficacy over time has not been established, according to Dr. Timothy I. Morgenthaler of the Center for Sleep Medicine at the Mayo Clinic in Rochester, Minn.
"The concern is that residual central breathing events may resolve over time with CPAP therapy, which is less expensive than adaptive servoventilation [ASV] and therefore may be a better option," he said at the annual meeting of the Associated Professional Sleep Societies.
To evaluate the longer-term efficacy of ASV relative to CPAP in individuals with complex sleep apnea syndrome (CSAS), Dr. Morgenthaler and his colleagues conducted a multicenter, prospective trial of 66 patients with CSAS, defined as those meeting the criteria for obstructive sleep apnea on diagnostic polysomnography who also had a central apnea index (CAI) score of 10 or higher while on optimal CPAP. The participants were randomized to treatment with either CPAP (n = 33) or ASV (n = 33), both titrated to optimal settings. Clinical and polysomnographic measures were collected at baseline and after 90 days of therapy, he said.
In addition to having a diagnosis of CSAS, eligible patients were older than 18 years and were naive to positive airway pressure treatment. The mean age of the study participants was 59.2 years, and the mean body mass index was 35.0 kg/m2, with no between-group differences. Additionally, about 9% of the patients had congestive heart failure and 13.6% reported chronic opiate use, Dr. Morgenthaler reported.
At baseline, the mean apnea-hypopnea index (AHI) and CAI scores were 37.7 and 3.2, respectively. After second-night treatment titration, the AHI scores were 4.7 in the ASV group vs. 14.1 in the CPAP group, and the respective CAI scores were 1.1 and 8.8, said Dr. Morgenthaler. At 90 days, the AHI for the ASV group was 4.4, compared with 9.9 for CPAP, and the respective CAI scores were 0.7 and 4.8, he said.
"In the intention-to-treat analysis, treatment was successful [defined as an AHI of less than 10] in 89.7% of the adaptive servoventilation group," while only 64.5% of the CPAP patients attained similar success, Dr. Morgenthaler stated, noting that there were no significant differences between the groups with respect to compliance, Epworth Sleepiness Scale (ESS) changes, or sleep apnea quality of life index (SAQLI) scores.
Although significantly more ASV patients showed evidence of treatment efficacy based on polysomnographic measures than did CPAP patients, "there were no similar symptomatic differences between the groups," Dr. Morgenthaler acknowledged. It is possible, but yet to be determined, that ASV-induced improvements on polysomnography will translate into other positive health outcomes, such as maximal suppression of Cheyne-Stokes respiration and central sleep apnea (CSR-CSA), as well as improvement in brain natriuretic peptide, in patients with heart failure, he said.
Dr. Morgenthaler disclosed that this study was supported by a grant from ResMed, the manufacturer of the ASV device used in the investigation.