![]() A previous editorial already emphasized that an independent double-blind study with a proper control group, preferably a sham device, would be necessary to answer the question whether device-guided breathing has any effect on blood pressure. ![]() Beneficial effects were not observed after excluding studies with high risk of bias or studies that were sponsored by or involved the manufacturer of the device. The overall effect estimate in the meta-analysis showed a small beneficial blood pressure lowering effect, but the authors of the meta-analysis stated that the results of the overall effect estimates should be interpreted with caution because of methodological flaws in most studies. After the publication of the guideline, two additional studies have been published. ![]() The conclusions of the writing group of the AHA statement were based on a meta-analysis and several other studies. As an increase in heart rate variability will lead to an increased baroreflex sensitivity, device-guided breathing may lead to lower blood pressure values. The baroreceptors measure blood pressure in the carotid arteries and the aorta, and an increase in pressure leads to parasympathetic activation and vice versa (negative feedback mechanism). Slow and regular breathing, guided by musical tones, will lead to a reduction of sympathetic activity and also to an increase in heart rate variability. Efforts aimed at reducing this autonomic imbalance may indeed be an effective therapy for hypertension. Sympathetic overactivity is hypothesized as an important contributing factor in the development of hypertension. Exercises are regarded as successful if the total exercise time is at least 45 min per week, preferably 15 min daily. Device-guided slow breathing aims at lowering the respiratory frequency into a so-called “therapeutic breathing zone”(less than 10 breaths per minute) through biofeedback by using an electronic device. In a scientific statement from the American Heart Association (AHA) regarding non-pharmacological options for lowering blood pressure, device-guided slow breathing is described as a reasonable treatment modality to reduce blood pressure (Class IIA, Level of Evidence B). Accepted non-pharmacological interventions are sodium restriction, losing weight, increasing physical activity, smoking cessation and optimizing alcohol consumption. Treatment of hypertension includes both pharmacological and non-pharmacological interventions. Based on the studies with an acceptable methodological quality, there is no clear evidence supporting a short-term beneficial effect on blood pressure by using device-guided breathing. All other studies were to some extend methodologically flawed. There is only 1 study that used a sham device as a control group. The remaining 4 studies, which had no employees of the manufacturer listed as co-author, observed no beneficial effects on blood pressure. Two sponsored trials showed beneficial effects of device-guided breathing, both used listening to music as a control group. Only 6 studies used acceptable control groups: listening to music, meditative relaxation exercises, or a sham-device. In total, 627 patients were included, of which 365 patients were allocated to device-guided breathing. ![]() Thirteen studies were included in this review. This review discusses all randomized controlled trials that have investigated the effects of device-guided breathing on blood pressure in patients with hypertension. The American Heart Association considers device-guided breathing as a reasonable treatment modality in their statement on non-pharmacological options for lowering blood pressure.
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