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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.
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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Skin Temperature Control During Simulated Blood Loss After Exercise Cold Stress | Experimental | 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. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Skin Surface Rewarming | Other | 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. |
| 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. |
| 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 |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| James Pearson, PhD | Univeristy of Colorado Colorado Springs | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| University of Colorado Colorado Springs | Colorado Springs | Colorado | 80918 | United States |
IPD that underlie the results presented in the publication.
Data may be requested up to 36 months following article publication.
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.
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| Type | Includes Protocol | Includes SAP | Includes ICF | Document Label | Document Date | Document Uploaded Date | Document File Name |
|---|---|---|---|---|---|---|---|
| Prot_ICF | Yes | No | Yes | Study Protocol and Informed Consent Form | Jan 3, 2023 | Feb 22, 2024 | Prot_ICF_000.pdf |
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| ID | Term |
|---|---|
| D006470 | Hemorrhage |
| ID | Term |
|---|---|
| D010335 | Pathologic Processes |
| D013568 | Pathological Conditions, Signs and Symptoms |
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Participants will complete trial 1 at the beginning of the study. Participants will then complete trials 2 through 5 in a random, counterbalanced order.
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Participants are blinded to the skin temperature control.
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| Skin Surface Warming | Other | 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. |
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| Skin Surface Heating | Other | 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. |
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| Skin Surface Cooling | Other | 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. |
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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 |