NCT06279897

LBNP Tolerance With Skin Warming After Exercise Cold Stress

Skin Rewarming After Exercise Cold Stress and Tolerance to Simulated Blood Loss

• Status: Active Not Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 10 (actual)
• Sponsor: University of Colorado, Colorado Springs · Academic / Other
• Sex: All
• Age: 18 Years – 40 Years
• Healthy volunteers: Accepted

Summary

Assess the effect of skin rewarming during lower body negative pressure upon arterial blood pressure and tolerance to simulated blood loss after exercise in the cold.

Detailed description

Individuals who have experienced a hemorrhagic insult are often wrapped in a warm blanket. In individuals who have exercise in a cold environment, it is unknown how this skin warming influence tolerance to simulated blood loss and whether there is an optimal temperature to warm the skin up to in order to lower blood pressure (permissive hypotension). After an initial study visit to examine exercise capacity (Visit 1), participants will complete four trials (Visits 2 through 5) After exercise in a cold environment, participants will have cold skin temperatures (\~82°F; Visit 2). Researchers will examine how increasing skin temperature to normal (\~90°F; Visit 3), warm (93°F; Visit 4) and hot (95°F; Visit 5) influences arterial blood pressure and tolerance to simulated blood loss compared to when the skin remains cold. This project will test the hypothesis that skin rewarming to \~95°F lowers arterial blood pressure without impairing tolerance to simulated blood loss (lower body negative pressure; LBNP) relative to when the skin is kept cold (82°F). Primary data include core and skin temperatures, arterial blood pressure and LBNP tolerance time. Secondary variables include skin blood flow and heart rate. After completing visit 1 first, all participants will complete visits 2 through 5 in a randomized order and participants are blinded. The order will be counterbalanced between participants.

Conditions

• Blood Pressure
• Blood Loss

Interventions

Type	Name	Description
OTHER	Skin Surface Rewarming	Sixty seconds after the onset of lower body negative pressure (LBNP) skin temperature will be increased to \~90°F and held here for the duration of the LBNP test.
OTHER	Skin Surface Warming	Sixty seconds after the onset of lower body negative pressure (LBNP) skin temperature will be increased to \~93°F and held here for the duration of the LBNP test.
OTHER	Skin Surface Heating	Sixty seconds after the onset of lower body negative pressure (LBNP) skin temperature will be increased to \~95°F and held here for the duration of the LBNP test.
OTHER	Skin Surface Cooling	Sixty seconds after the onset of lower body negative pressure (LBNP) skin temperature will remain lowered to \~82°F for the duration of the LBNP test.

Timeline

• Start date: 2022-01-24
• Primary completion: 2026-09-30
• Completion: 2026-09-30
• First posted: 2024-02-28
• Last updated: 2025-03-27

Locations

1 site across 1 country: United States