Keeping Your Cool

For many years, EMS providers have used cold packs, moist towels, gauze pads and, in extreme cases, fluid replacement to return body temperature to normal levels.

Shafer Enterprises, based in Stockbridge, GA, recently introduced the Cool Shirt Personal Cooling System, which uses medical-grade capillary tubing stitched into shirts, hoods and vests to provide sustained cooling, as well as on-demand cooling in warm environments.

Cool Shirts are made of either 100% cotton or Nomex, and are designed to be worn as an undergarment with uniform shirts or turnout-type coats. Small-diameter tubing is stitched throughout the shirts and connects to two plastic connectors. The nylon vests have a similar tubing configuration. The concept is similar to residential flooring with tubing that runs below the floor to maintain warm temperatures. The water pumped into Cool Shirts and Cool Vests ranges from 45-65 degrees. The shirts and vests can be washed in warm or cold water.

The cooling system is a single unit, 14" x 9.5" x 11.5" high, that holds one gallon of water, plus block or cubed ice, with a small pump that pumps water into the shirt or vest via two double-insulated rubber hoses, ranging from 8´ to 20´ in length. A larger version of the cooling system holds 15 gallons of water and can accommodate six shirts or vests at one time. All of the cooling systems can be adapted to connect to a 12-volt or 110-volt power source, and include a comfort cooler that can be worn around the waist to allow the wearer free movement without having to reconnect to a cooling system. A maintenance additive, which is required to prevent buildup in the tubing system, is an additional cost. When the pump is turned on, the wearer can feel cool water flowing through the tubes in the shirt or vest almost instantly. It is recommended that the vest be submerged in water and patted dry prior to use.

For the purposes of this review, we used a Cool Vest. Prior to use, the vest was submerged in tepid water for approximately one minute, then patted dry with a towel, although it did retain moisture. The vest was then connected to the cooling unit and “charged” for approximately five minutes before being worn by a 35-year-old male, weighing 165 pounds and in good physical condition. The vest was put on over a cotton t-shirt, with another cotton t-shirt over the vest. The vest added an additional 3–5 pounds of weight and had an immediate cooling effect. The subject then ran 5 kilometers (3.1 miles) in 30 minutes in 88ºF heat with 66% humidity. Halfway through the run, the vest remained slightly damp, but not overly cool. At the end of the run, the vest remained damp, but had lost most of its cooling effect. The vest was then reattached to the cooling unit for 5 minutes, during which time it recooled and the moisture in the vest retained the cooling effect from the tubing.

The shirts and vest are quite durable and should withstand multiple uses with proper maintenance of the system. The only potential issue might stem from a hole or kink in the tubing.

Cool Shirts systems are ideal for agencies that operate in warm temperatures on a constant basis, and to assist with responder rehab in warm environments. The ability to rapidly cool providers, as well as maintain cool body temperatures, could prove valuable in the prehospital setting. For more information, go to www.coolshirt.net.

Timothy J. Perkins, BS, EMT-P, is the EMS systems planner for the Virginia Department of Health's Office of EMS, host of EMS World's EMS Squadcast podcast and a member of the EMS World editorial advisory board.