Short-term effects of arm baths on blood pressure in participants with arterial hypertension - a randomized crossover...

Hypertension is the predominant risk factor for premature cardiovascular disease, and contributes to heart failure, chronic kidney disease, and stroke. As of recently, scientists began to systematically investigate the vast physiological potential of hydrotherapy in individuals with cardiovascular disease. Hot baths in particular have been shown to transiently reduce arterial stiffness and to exert vasodilatory effects. Potentially beneficial in patients with uncontrolled hypertension, hot arm baths (HAB) have rarely been put to the test in randomized-controlled trials.

Based on the hypothesis that HAB may exert short-term blood pressure-lowering effects, a monocentric, randomized-controlled pilot study was performed in participants with arterial hypertension. In a crossover design, participants received a HAB with a temperature of 45 °C and a thermoneutral arm bath (TAB) with a temperature of 28 °C for five minutes each, with a post-interventional observation period of 90 min. Effects on systolic blood pressure (SBP) and diastolic blood pressure (DBP) as well as on heart rate (HR) and hand and foot temperature (HT, FT) were measured in close intervals (after 1, 5, 10, 15, 30, 60 and 90 min). The washout period between both interventions was seven days.

54 participants with uncontrolled hypertension were included to the study, of which four participants had to be excluded from the analysis because they did not show up for the second intervention. The mean age of the remaining 50 participants in group A und in group B were 61 and 62 years, respectively. The participants in both groups were slightly overweight (group A: BMI 25.2 kg/m², group B: BMI 27.1 kg/m²). The majority of participants in both groups took antihypertensive medication. Analysis revealed no carry-over effect. The analyses of treatment effects showed a significant decrease from baseline of DBP 5, 10 and 15 min after the HAB in comparison with the TAB. In addition, we found statistically significant differences of the two interventions in the changes from baseline of the HR after 1 and 5 min and HT after 1, 5, 10, 15 and 30. No major side effects were reported.

HAB could be used as rapid-acting add-on tool in conjunction with pharmacotherapy to manage uncontrolled hypertension in various contexts at home.