Diabetes (DM), Lower Limb Amputation Below Knee, Skin Temperature Change, Vascular Reactivity
Conditions
Brief summary
To protect against excessive body temperatures, local thermoregulatory mechanisms include temperature sensory nerves (responsive to warm or cool stimuli) and vasomotors (muscles that constrict or dilate blood vessels). When the temperature changes occur, the temperature sensory nerves will detect warm or cool and communicate this sensation to the brain. This is called perceiving a sensation and will often elicit a behavioral change, such as donning additional clothes or moving to a different environment. Simultaneously, vasomotors will dilate or constrict to promote or prevent heat dissipation to the environment, respectively. As skin temperatures increase, perspiration may provide some thermal relief through evaporative cooling. However, the prostheses worn by individuals with lower limb amputations are impermeable to moisture and prevent evaporative cooling. Prosthetic materials are also excellent thermal insulators, contributing to skin temperature increases. Thermoregulation problems are compounded by diabetes, a common co-morbidity of many who experience lower limb amputation. For those who wear lower limb prostheses, many endure thermal discomfort. This research explores the relationship between skin temperature, perception, and thermoregulation. The investigators aim to discover the temperature at which individuals with lower limb amputation perceive warm and cool stimuli. The investigators also aim to discover the vascular response that occurs when temperature changes are perceived. The goals are to determine temperature sensation thresholds of the lower limb, vascular reactivity, and the effect of diabetes and amputation.
Detailed description
This study will include four groups of participants including individuals with diabetes, individuals without a diagnosis of diabetes, individuals with lower limb amputations of diabetic etiology, and individuals with lower limb amputations of non-diabetic etiologies. To measure temperature perception, a thermode (a temperature changing device about the size of a coffee cup) will be placed on the lower leg of each participant. The thermode also included a laser Doppler flow meter, embedded in the center of the thermode, to measure blood flow in response to changes in skin temperature. The experimental protocol begins with the thermode set for 3 minutes at 30 °C, 32 °C, 34 °C, and 35 °C (random order). The temperature will then be either increased or decreased at a slow rate of 0.2 °C/sec until the participant perceives either a warming or cooling sensation. The analysis plan includes determining the threshold at which a temperature change was perceived relative to each initial temperature, whether there are differences in blood flow (vascular reactivity) when thermal stimuli are detected, and these measurements are altered by diabetes or amputation. The general hypotheses are that these populations will have (1) different warm and cool temperature perception thresholds depending on the initial skin temperature and (2) different changes in skin blood flow as a function of their temperature perception thresholds.
Interventions
OTHERWarming stimulus starting at 30 C initial temperature
A warming stimulus starting at 30 C initial temperature was applied at a rate of 0.2 C/second until the participant perceived the stimulus or the termination temperature of 42 C was reached.
OTHERWarming stimulus starting at 32 C initial temperature
A warming stimulus starting at 32 C initial temperature was applied at a rate of 0.2 C/second until the participant perceived the stimulus or the termination temperature of 42 C was reached.
OTHERWarming stimulus starting at 34 C initial temperature
A warming stimulus starting at 34 C initial temperature was applied at a rate of 0.2 C/second until the participant perceived the stimulus or the termination temperature of 42 C was reached.
OTHERWarming stimulus starting at 35 C initial temperature
A warming stimulus starting at 35 C initial temperature was applied at a rate of 0.2 C/second until the participant perceived the stimulus or the termination temperature of 42 C was reached.
OTHERCooling stimulus starting at 30 C initial temperature
A cooling stimulus starting at 30 C initial temperature was applied at a rate of 0.2 C/second until the participant perceived the stimulus or the termination temperature of 18 C was reached.
OTHERCooling stimulus starting at 32 C initial temperature
A cooling stimulus starting at 32 C initial temperature was applied at a rate of 0.2 C/second until the participant perceived the stimulus or the termination temperature of 18 C was reached.
OTHERCooling stimulus starting at 34 C initial temperature
A cooling stimulus starting at 34 C initial temperature was applied at a rate of 0.2 C/second until the participant perceived the stimulus or the termination temperature of 18 C was reached.
OTHERCooling stimulus starting at 35 C initial temperature
A cooling stimulus starting at 35 C initial temperature was applied at a rate of 0.2 C/second until the participant perceived the stimulus or the termination temperature of 18 C was reached.
Sponsors
VA Puget Sound Health Care System
Study design
Allocation
RANDOMIZED
Intervention model
FACTORIAL
Primary purpose
SUPPORTIVE_CARE
Masking
SINGLE (Subject)
Eligibility
Sex/Gender
ALL
Age
18 Years to 70 Years
Healthy volunteers
Yes
Inclusion criteria
for All Participants: * Able to ambulate without upper extremity aids * Able to attend study visits * Able to sense a Semmes-Weinstein 5.07 monofilament applied to proximal lateral aspect of test limb calf * Cognitively aware Additional Inclusion Criteria for Individuals with Lower Limb Amputation * Have been fit with a prosthesis * Have used a prosthesis for at least six months * Wear the prosthesis for at least four hours per day by self-report
Exclusion criteria
for Individuals with Lower Limb Amputation: \- Have no residual limb ulcers
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Thermal perception threshold | Day 1 | The thermal perception threshold is the difference between the initial temperature and the temperature at which the participant detected the thermal stimulus |
| Skin blood flow difference | Day 1 | The skin blood flow difference is the difference between the skin blood flow at the initial temperature and the skin blood flow at the temperature at which the participant detected a thermal stimulus |
Countries
United States
Outcome results
None listed