LBNP Tolerance With Skin Warming After Exercise Cold Stress

Blood Pressure Clinical Trial

Official title:

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

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT06279897
• Other study ID #: 2023-068
• Status: Recruiting
• Phase: N/A
• Start date: January 24, 2022
• Est. completion date: September 30, 2025

Study information

• Verified date: February 2024
• Source: University of Colorado, Colorado Springs
• Contact: James Pearson, PhD
• Phone: 7192553806
• Email: jpearso5[@]uccs.edu
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial 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.

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.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 10
• Est. completion date: September 30, 2025
• Est. primary completion date: September 30, 2025
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 40 Years

Eligibility

Inclusion Criteria:

• 18 and 40 years old

• free of known disease and illness

• Speak English

• Systolic blood pressure <140mmHg

• Diastolic blood pressure <90 mmHg

Exclusion Criteria:

• Currently pregnant or breast feeding

• Individuals with diagnosed with cardiac, respiratory, neurological and/or metabolic illness or disease.

• Currently taking prescribed or over the counter medications known to influence the cardiovascular, pulmonary, renal and/or central nervous system.

• Current use of tobacco or nicotine products

• Any physical limitations that impede completion of the tests, such as exercise tests will also be an exclusion criteria.

• Body mass< 80 pounds body weight

• Appendectomy

Related Conditions & MeSH terms

• Blood Loss
• Blood Pressure
• Hemorrhage

Intervention

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.
• 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.
• 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.
• 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.

Locations

Country	Name	City	State
United States	University of Colorado Colorado Springs	Colorado Springs	Colorado

Sponsors (1)

Lead Sponsor	Collaborator
University of Colorado, Colorado Springs

Country where clinical trial is conducted

United States, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Arterial blood pressure	During simulated blood loss is the reduction in arterial blood pressure greater with progressive skin heating	Before and during lower body negative pressure (LBNP) procedure
Primary	Tolerance to simulated blood loss	Tolerance to LBNP will be quantified using the cumulative stress index (CSI) calculated by summing the time at each level of LBNP multiplied by that level (i.e., 20 mmHg * 3 min + 30 mmHg * 3 min + 40 mmHg * 3 min, etc.) until test termination.	Lower body negative pressure test duration in all trials.
Secondary	Core temperature	Measured using rectal probe or intestinal pill and indicative of change in internal body temperature.	Throughout exercise cold exposure and continuously during LBNP
Secondary	Cutaneous Vascular Conductance	Skin blood flow measured using laser Doppler flowmetry (AU) will be referenced relative to arterial blood pressure (mmHg) and expressed as cutaneous vascular conductance (CVC; AU/mmHg)	Before and during lower body negative pressure (LBNP) procedure