LBNP Tolerance With Skin Warming After Exercise Cold Stress

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

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.

Study Overview

• Status: Active, not recruiting
• Conditions: Blood Pressure; Blood Loss
• Intervention / Treatment: Other: Skin Surface Rewarming; Other: Skin Surface Warming; Other: Skin Surface Heating; Other: Skin Surface Cooling

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.

• Study Type: Interventional
• Enrollment (Actual): 10
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Colorado
    • Colorado Springs, Colorado, United States, 80918
      • University of Colorado Colorado Springs

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Skin Temperature Control During Simulated Blood Loss After Exercise Cold Stress; After exercise in the cold and participants skin will remain cold (~82°F), be returned to normal (~90°F), be slightly warmed (~93°F) or heated (~95°F) sixty seconds after the onset of LBNP.

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 Names: Normothermic Trial; 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 Names: Warm Trial; 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 Names: Hot Trial; 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.; Other Names: Cold Trial; Control Trial

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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
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 Outcome Measures

Outcome Measure	Measure Description	Time Frame
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
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

Collaborators and Investigators

• Sponsor: University of Colorado, Colorado Springs
• Investigators: Principal Investigator: James Pearson, PhD, Univeristy of Colorado Colorado Springs

Study record dates

Study Major Dates

• Study Start (Actual): January 24, 2022
• Primary Completion (Estimated): September 30, 2026
• Study Completion (Estimated): September 30, 2026

Study Registration Dates

• First Submitted: February 7, 2024
• First Submitted That Met QC Criteria: February 22, 2024
• First Posted (Actual): February 28, 2024

Study Record Updates

• Last Update Posted (Actual): March 27, 2025
• Last Update Submitted That Met QC Criteria: March 26, 2025
• Last Verified: March 1, 2025

More Information

Terms related to this study

• Keywords: Blood Loss; Arterial Blood Pressure; Permissive Hypotension; Cold Stress; Skin Warming
• Additional Relevant MeSH Terms: Pathologic Processes; Hemorrhage
• Other Study ID Numbers: 2023-068

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: IPD that underlie the results presented in the publication.
• IPD Sharing Time Frame: Data may be requested up to 36 months following article publication.
• IPD Sharing Access Criteria: Data will be made available upon reasonable request. Requests should be directed to jpearso5@uccs.edu. To gain access, data requestors will need to sign a data access agreement.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No