Quantification of Cardiovascular Regulation Applying Heart Rate Variability Analyses for Different Warm and Moist Chest Compresses in Healthy Subjects

Background: In integrative medicine, complementary healing methods, such as external applications (massages, rhythmic rubs, and compresses), are part of the practice and clinical application and have proven their therapeutic effect in various fields. Objective: Aim of this exploratory, controlled, single-blinded study was to investigate the effects of three different warming chest compresses on cardiovascular regulation by analyzing heart rate variability (HRV) in healthy subjects. Methods: Over a period of 4 weeks, three different warming chest compresses (a hot water compress, a ginger powder compress, and a mustard flour compress) in 30 healthy subjects were analyzed. For all subjects, 48-h long-term electrocardiograms were recorded, and afterward, epochs of 5 min length extracted and analyzed by different linear and nonlinear HRV indices. Results: A moist chest compress did not result in any significant short- and long-term stimulation of the autonomic regulation, except for a short-term significant decrease in heart rate (meanNN, p < 0.05). Warm and moist chest compresses with ginger flour led to significantly increased HRV (sdNN, p < 0.05; symbolic dynamics2, p < 0.05) and its complexity (renyi4 entropy, p < 0.05) and a significant decrease in heart rate (meanNN, p < 0.00036), and thus to a short-term relaxation effect. In contrast, warm and moist chest compresses with mustard flour led to significantly decreased HRV and their complexity (time-, frequency-, and nonlinear dynamics domain, p < 0.00036), which can be interpreted as a stress reaction of the autonomous nervous system. Conclusions: The application of chest compresses led to short-term relaxation effects (ginger) as well as short-term stress effects (mustard) but not to any significant longer-term effect on HRV in healthy subjects.