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Abstract: FR-PO738

Passive Heat Therapy Lowers Blood Pressure and Improves Vascular Function in Older Adults With Reduced Kidney Function

Session Information

Category: Hypertension and CVD

  • 1502 Hypertension and CVD: Clinical‚ Outcomes‚ and Trials

Authors

  • Brunt, Vienna E., University of Colorado Boulder, Boulder, Colorado, United States
  • Bazzoni, Amy, University of Colorado Boulder, Boulder, Colorado, United States
  • Nguyen, Kathy H., University of Colorado Boulder, Boulder, Colorado, United States
  • Chonchol, Michel, University of Colorado - Anschutz Medical Campus, Aurora, Colorado, United States
  • Minson, Christopher T., University of Oregon, Eugene, Oregon, United States
  • Seals, Douglas R., University of Colorado Boulder, Boulder, Colorado, United States
Background

Passive heat therapy—chronic use of hot tubs or saunas—lowers blood pressure (BP) and reduces risk of cardiovascular-related mortality and hypertension in healthy populations but has not been studied in the context of kidney disease. We investigated if heat therapy could lower BP and improve vascular function in middle-aged and older adults (57-79 yrs) with reduced kidney function (MDRD eGFR at baseline <90 mL/min/1.73 m2).

Methods

As part of a randomized, parallel-design, clinical trial (NCT05300971), subjects underwent 30 x 60-min sessions over 8-10 weeks (~3x/week) of hot water immersion (n=9; 40°C water) or thermoneutral water immersion (n=8; “sham”; 36°C water; no change in body temperature). BP and vascular function were assessed before and after the intervention (24-72 h after the last session).

Results

Data are mean±SE. Baseline eGFR was comparable across groups: heat therapy, 74±3 vs. sham, 73±4 mL/min/1.73 m2 (P=0.75). Remarkably, heat therapy reduced casual seated systolic BP in every subject. On average, systolic BP changed from 124±4 to 114±4 mmHg in the overall group (P<0.001), and from 119±4 to 109±4 mmHg in the subgroup of subjects with baseline eGFR <75 ml/min/1.73 m2 (n=5; P=0.01). Casual diastolic BP was also reduced (overall group: 80±3 to 75±3 mmHg; lower eGFR subgroup: 76±4 to 70±3 mmHg; both P<0.01). In the overall group, heat therapy improved vascular endothelial function (brachial artery flow-mediated dilation: 4.7±0.6 to 6.3±1.1%Δ units, P<0.01) and reduced aortic stiffness (carotid-femoral pulse wave velocity: 8.8±0.6 to 8.1±0.8 m/sec, P=0.06). The magnitude of improvements in these vascular outcomes were similar in the subgroup of subjects with baseline eGFR <75 ml/min/1.73 m2 vs. the overall group. Serum C-reactive protein tended to be reduced in the overall group, with the largest reductions observed in subjects with eGFR <75 ml/min/1.73 m2 (5.5±2.8 to 2.1±0.7 mg/L, P=0.19). There were no changes in any outcomes in sham subjects.

Conclusion

Passive heat therapy substantially lowers BP in older adults with mildly reduced kidney function, accompanied by improved vascular function. Heat therapy may be a novel lifestyle intervention for treating hypertension and lowering cardiovascular risk and should be further studied in patients with more advance kidney disease.