Hypothermia Rewarming With Distal Limb Warming
Condition: Rewarming by Shivering Heat Production Only; Rewarming by Arm and Leg Immersion in Warm Water; Rewarming by Arm and Leg Exposure to Fluidotherapy
MeSH terms: Hypothermia
Study type: Interventional

Summary: 
      The study will compare the rewarming effectiveness of heat donation through the distal arms
      and legs during rewarming of mildly hypothermic subjects. Warming will be accomplished
      through either warm water immersion; and fluidotherapy. The investigators hypothesize that
      fluidotherapy will be as, or more, effective compared to warm water immersion
    

Detailed description: 
      Dr. Gordon Giesbrecht is studying/comparing the effectiveness of heat donation through the
      distal arms and legs in rewarming a mildly hypothermic individual. Warming will be
      accomplished through either warm water immersion; and fluidotherapy.

      Procedure. Eight participants will be cooled in 8°C water on three occasions and then warmed
      by each of three warming conditions. The study will include following specific procedures:
      Anthropometric data which includes age, weight, height, and measurements of skinfold
      thickness at four sites- biceps, triceps, subscapularis, and suprailiac will be collected.
      Participant's heart rate and electrocardiogram will be monitored continuously throughout the
      experiment.

      Participants will be instrumented as follows:

        1. About 12 heat flux disks (2 cm in diameter) will be taped to the skin on the arms, legs,
           torso, head etc. to measure skin temperature and heat transfer from the skin.

        2. Three ECG leads will be affixed to the skin.

        3. Core temperature will be measured with a disposable esophageal thermocouple. A thin,
           flexible tube will be inserted through the nose, to midway down the esophagus at the
           level of the heart.

        4. Oxygen consumption will be continuously measured with a metabolic cart. Participants
           will be asked to wear a face mask which will collect the expired breath during the
           cooling as well as the rewarming periods.

      Conditions: The three treatment methods are as follows.

      A. Spontaneous rewarming (Shivering only) - In this control condition, no external heat will
      be provided and the participant will rewarm spontaneously with the heat produced from
      shivering.

      B. Warm water distal extremities immersion - Distal arms and legs will be immersed in warm
      water at 45°C for rewarming.

      C.Fluidotherapy distal extremities rewarming - Distal arms and legs will be immersed in
      Fluidotherapy equipment for rewarming at 50°C.

      Rewarming procedures will be administered either for a period of 60 minutes or until core
      temperature returns to normal values ( ̴ 36.5-37˚C). Following that, participants will be
      placed in a warm water bath (40-42˚C).

      Research Design: Each of the three experimental trials, separated by at least 48 hours. On
      each of the three trials, participants will be immersed up to the level of the sternal notch
      in 8˚C for up to 60 minutes or until the core temperature falls to 35˚C. The participant will
      then exit the water, be dried off and rewarmed with either lie inside a vapor barrier within
      a hooded sleeping bag with the head inside the hood, or sitting with their distal arms and
      legs immersed in either Fluidotherapy at 50°C or warm water at 45°C. The rewarming will be
      administered for 60 minutes or until the core temperature returns to normal values
      (̴36.5-37˚C). The order of warming methods will follow a balanced design.
    

Intervention name(s): Fluidotherapy warming device
Intervention type(s): Device
Intervention description(s): Device uses airborne heated cellulose particles which are blown against the skin to provide convective warming.
Other intervention name(s): Chattanooga Fluidotherapy model 115D
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: rewarming; core cooling; afterdrop; hospital treatment; hypothermia