Assessment of Vasomotion of People With Spinal Cord Injury

Spinal cord injury (SCI), causes loss of supra-spinal control of the sympathetic nervous system and in some cases loss of sensation. As a result, people with SCI have impaired thermoregulatory system and the consequence of this thermoregulatory dysfunction, is that they cannot respond to the environmental changes. All the above lead to dysregulation in vasomotor tone, skeletal muscle shivering and sweating dysfunction. It is well known that skin plays an important role in regulating body temperature and regulates interactions between the environment and human body. A previous study in people with incomplete SCI showed that there are no differences in core temperature between patients with different level of mobility and sensation and different level of lesion, but there are significant differences in skin temperature. As mentioned above people with SCI have an impaired thermoregulatory capacity due to sudomotor and vasomotor dysfunction and that leads to greater thermal strain during rest and exercise when they expose to hot conditions. A previous study that performed exercise in people with SCI, highlights the fact that because of the impaired evaporative heat loss during exercise in hot conditions, they are in great risk. Because of this risk they propose different cooling strategies that promote evaporation such as fans and water spraying. It is therefore important to observe the thermoregulatory function (vasomotion and sudomotor) in people with SCI when they are exposed to different environments (cold, neutral and warm).

The participants will visit the laboratory three times. At each time the environmental chamber will simulate a different environment in a random order for each participant. The three different environments will be as follow:

1. Cold environment 15-17°C and 40-50% relative humidity
2. Thermoneutral environment 22-24°C and 40-50% relative humidity
3. Warm environment 33-35°C and 40-50% relative humidity The participants will stay in a sited position for 20 minutes in order to collect baseline data and to allow to their blood flow and body temperature adapt to the exposing environmental condition each time. Immediately after the baseline period the participants will immerse their left hand and foot in warm water (34-36°C) for 5 minutes for a consistent starting (hand and foot) temperature. Following that participants will immerse their hand and foot in cold water (8°C) for 40 minutes. This procedure will be repeated in every measurement and it will only change the environment.

Anthropometric data \[self-reported age, self-reported body stature and body mass (DXA, Lunar, GE Healthcare Boston, Massachusetts, U.S)\] will be collecting at the beginning of the first measurement. Medical history of all the participants will be recording. During the study, continuous heart rate (Polar Team2. Polar Electro Oy, Kempele, Finland), core temperature (telemetric capsules BodyCap, Caen, France), mean skin temperature (wireless thermistors iButtons type DS1921H, Maxim/Dallas Semiconductor Corp., USA), finger temperature ((Smartreader 8 Plus, ACR, Vancouver, Canada), skin blood flow and sweat rate data (laser Doppler flow-meter PeriFlux System 5010, function unit; Perimed, Stockholm, Sweden and PeriFlux System 4002, master unit, satellite unit; Perimed, Stockholm, Sweden) will be collecting. Blood pressure will also be monitoring every 10 minutes with an automatic sphygmomanometer (Omron Healthcare M6 comfort, Japan). Skin temperature data will be collecting from four sites (chest, arm, thigh, and leg) and will be expressed as mean skin temperature according to the formula of Ramanathan (Tsk = \[0.3(chest + arm) + 0.2(thigh + leg)\]. Questionnaires (thermal sensation scale: -3 = cold; +3 = hot) will be used to assess participants' thermal comfort/sensation and pain.

Eligibility Criteria:
Inclusion Criteria:

* People with spinal cord injury below thoracic spine 6, at least six months after the injury.
* Healthy adult participants, non-smokers, no disease and/or taking medicines

Exclusion Criteria:

* People under the age of 18;
* People taking any medicines that affect vasomotion (e.g. for hypertension, thrombosis, etc.)
* People with other chronic diseases (e.g. diabetes)