Local Heat Lowers Blood Pressure in Supine Hypertension

Heating pad reduces nocturnal supine hypertension, study shows. (©VChalup,AdobeStock)

Local heat therapy applied overnight effectively lowers blood pressure in patients with both primary autonomic failure and nocturnal supine hypertension, according to a study presented at AHA’s Hypertension 2019 Scientific Sessions in New Orleans.

Supine hypertension, which is present in about half of patients with autonomic failure, complicates orthostatic hypotension treatment and induces nocturnal polyuria, which worsens morning orthostatic hypotension. 

Previous research has shown that short exposure to local passive heat acutely decreased systolic blood pressure by around 25 mmHg in these patients due to decreases in stroke volume and cardiac output. This study looked at whether local passive heat therapy applied overnight would lower nocturnal blood pressure and polyuria, and improve early morning orthostatic hypotension.

Researchers studied 10 patients with autonomic failure and supine hypertension, with an average age of 76 years and a mean supine systolic blood pressure of 168 mm Hg. In a two-night crossover study, participants received heat at 100 degrees Fahrenheit from a medical grade heating pad placed under their torso on one night, and an unheated pad was placed in the same position on the second night. Supine blood pressure was monitored every two hours from 8 p.m. to 8 a.m., and heat therapy was applied from 10 p.m. to 6 a.m.

Heat therapy applied during sleep decreased systolic blood pressure, with a maximum reduction of 30 mm Hg after four hours of heat, but did not decrease nocturnal diuresis or improve morning orthostatic hypotension.

“In many patients with autonomic failure, heat exposure decreases blood pressure by shifting blood to skin vessels,” said study lead Luis E. Okamoto, M.D., of Vanderbilt University Medical Center in Nashville, Tenn.

“Local heat therapy offers a novel non-pharmacologic approach to treat this condition, but future studies are needed to assess the long-term safety of this approach,” the authors wrote.

REFERENCE

“Local Passive Heat in the Treatment of Nocturnal Supine Hypertension in Autonomic Failure.” Luis E Okamoto, Jorge E Celedonio, Emily C Smith, et al. Sept 6, 2019.  Hypertension 2019. Abstract number 043.