OSA Therapy Effective in Improving Autonomic Function Measures

A review published in Sleep found that obstructive sleep apnea (OSA) therapy could help improve autonomic function measures, such as reduced sympathetic activity without increased improvement in parasympathetic function, and reduce the risk of cardiovascular disease.

Patients with OSA have a cyclical pattern of heart rate and blood pressure surges while sleeping, which correlates to the activation of the sympathetic and parasympathetic nervous system, which regulate the fight or flight response and regulate a calming emotional state, respectively. This review aimed to identify studies to evaluate the effectiveness of OSA therapy on autonomic function.

Studies were included in the review if they examined patients who were 18 years or older and had a diagnosis of OSA and assessed intervention groups who received any intervention or treatment for OSA—including positive airway pressure (PAP), positional therapy, weight loss, or surgical interventions—vs a control group.

The search for studies took place using MEDLINE, Embase, and Scopus, with the last search taking place on December 9, 2020. Index of autonomic function, unit of measurement, time of measurement, mean and SD with and without OSA treatment, and treatment characteristics were extracted from the studies.

There were 43 studies included in the review, 31 of which compared autonomic function in 649 patients before and after PAP therapy, 2 studies that were conducted in 22 patients before and after mandibular advancement device, and 1 study in 40 patients before and after surgery to correct OSA. Only 38 studies were considered for meta-analysis.

The 24 studies that investigated the effect of OSA treatment on heart rate variability (HRV) were categorized into global, sympathetic, parasympathetic, low frequency, and very low frequency measures.

Only very low frequency HRV decreased with OSA treatment (Hedges’ g, –0.51; 95% CI, –0.93 to –0.09). A meta-regression analysis found that treatment duration was correlated with a larger decrease in very low frequency HRV (beta, –0.31; 95% CI, –0.61 to –0.02) and that older age reduced the benefits of the treatment (beta, 0.07; 95% CI, 0.00-0.15).

There was a large reduction in catecholamine levels with OSA treatment (Hedges’ g, ­–0.60; 95% CI, –0.94 to –0.27). Large reductions were also found in muscle sympathetic nerve activity, with burst frequency (Hedges’ g, –1.07; 95% CI, –1.64 to –0.50), burst incidence (Hedges’ g, –1.15; 95% CI, –1.68 to –0.62), and other measures of muscle sympathetic nerve activity (Hedges’ g, –1.15; 95% CI, –1.68 to –0.62) all seeing reductions.

This study had some limitations. There was insufficient data to examine the influence of treatment adherence on autonomic function. Mode of therapy, duration of therapy, baseline OSA severity, and patient demographics also could not be assessed due to limited data. Results on the dose-response effect of treatment and potential sex differences in treatment should be taken with caution due to the smaller number of studies being included in the meta-regression.

The researchers concluded that OSA therapy has strong evidence suggesting its effect on reducing sympathetic activity, but not parasympathetic activity, within autonomic function.

Reference

Dissanayake HU, Bin YS, Sutherland K, Ucak S, de Chazal P, Cistulli PA. The effect of obstructive sleep apnea therapy on cardiovascular autonomic function: a systematic review and meta-analysis. Sleep. Published online September 15, 2022. doi:10.1093/sleep/zsac210