Experience With Adaptive Servo-Ventilation Among Veterans in the Post-SERVE-HF Era
Background: The sleep medicine community has struggled to identify the ideal role for adaptive servo-ventilation (ASV) therapy following a study that found increased mortality in patients with central sleep apnea (CSA) and heart failure with reduced ejection fraction who used ASV therapy. We aimed to identify characteristics of patients who benefit from ASV therapy.
Methods: We performed a record review of all patients treated with ASV therapy at the Hampton Veterans Affairs Medical Center in Virginia from January 1, 2015, to April 30, 2020. Clinical and polysomnographic characteristics of patients adherent to therapy were compared with those that were not adherent.
Results: Our cohort of 31 patients was entirely male with a mean age of 67.2 years, body mass index of 34.0, and Epworth Sleepiness Scale score of 10.9. Primary CSA was initially diagnosed in 3 patients (10%), comorbid obstructive sleep apnea (OSA) and CSA in 9 (29%), and primary OSA in 19 (61%). Seventeen patients (55%) met minimal adherence criteria with ASV therapy. The obstructive apnea-hypopnea index (AHI), as a proportion of the total pretreatment AHI, was higher in adherent patients (81.5%) vs nonadherent patients (46.7%) (P = .02). The median residual AHI was lower in the adherent group, both as absolute values (1.7 vs 4.7 events/h; P = .004) and as a percentage of the pretreatment AHI (3.1% vs 10.2%; P = .002).
Conclusions: Patients using ASV devices regularly have a larger component of obstructive sleep-disordered breathing and obtain greater objective benefit from ASV than those that do not. This understanding may help to identify patients that will most benefit from this debated form of therapy.
Limitations and Future Directions
This retrospective, single-center study may have limited applicability to other populations. Adherence was used as a surrogate for subjective benefit from treatment, though benefit was not confirmed by the patients directly. Only patients seen in follow-up for documentation of the ASV download were identified for inclusion and data analysis. As a single center, we risk homogeneity in the treatment algorithms, though sleep medicine treatments are often decided at the time of the sleep studies. Studies and treatment recommendations were made at a variety of sites, including our sleep center, other US Department of Veterans Affairs hospitals, in the community network, and at US Department of Defense centers. Our population was homogenous in some ways; notably, 100% of our group was male, which is substantially higher than both the veteran population and the general population. Risk factors for OSA and CSA are more common in male patients, which may partially explain this anomaly. Lastly, with our small sample size, there is increased risk that the results seen occurred by chance.
There are several areas for further study. A larger multicenter study may permit these results to be generalized to the population and should include subjective measures of benefit. Patients with primarily CSA were largely absent in our group and may be the focus of future studies; data on predictors of treatment adherence in CSA are lacking. With the availability of consistent older adherence data, comparisons may be made between the efficacies of clinical practice habits, including treatment efficacy, before and after the results of the SERVE-HF trial became known.
Conclusions
In selected patients with preserved LVEF, ASV therapy appears especially effective in patients with OSA combined with CSA. Adherence to ASV treatment was associated with higher obstructive AHI during the baseline PSG and with a greater reduction in the AHI. This understanding may help guide sleep specialists in personalizing treatments for sleep-disordered breathing. Because objective efficacy appears to be important for therapy adherence, clinicians should be able to consistently determine the obstructive and central components of the residual AHI, thus taking all information into account when optimizing the treatment. Additionally, both OSA and CSA pressure requirements should be considered when developing ASV devices.
Acknowledgments
We thank Martha Harper, RRT, of Hampton Veterans Affairs Medical Center (HVAMC) for helping to identify our patients and assisting with data collection. This material is the result of work supported with resources and the use of HVAMC facilities.
