title: Field torso-warming modalities: a comparative study using a human model.
abstract: OBJECTIVE
  To compare four field-appropriate torso-warming modalities that do not require alternating-current (AC) electrical power, using a human model of nonshivering hypothermia.
  
  
  METHODS
  Five subjects, serving as their own controls, were cooled four times in 8 degrees C water for 10-30 minutes. Shivering was inhibited by buspirone (30 mg) taken orally prior to cooling and intravenous (IV) meperidine (1.25 mg/kg) at the end of immersion. Subjects were hoisted out of the water, dried, and insulated and then underwent 120 minutes of one of the following: spontaneous warming only; a charcoal heater on the chest; two flexible hot-water bags (total 4 liters of water at 55 degrees C, replenished every 20 minutes) applied to the chest and upper back; or two chemical heating pads applied to the chest and upper back. Supplemental meperidine (maximum cumulative dose of 3.5 mg/kg) was administered as required to inhibit shivering.
  
  
  RESULTS
  The postcooling afterdrop (i.e., the continued decrease in body core temperature during the early period of warming), compared with spontaneous warming (2.2 degrees C), was less for the chemical heating pads (1.5 degrees C) and the hot-water bags (1.6 degrees C, p < 0.05) and was 1.8 degrees C for the charcoal heater. Subsequent core rewarming rates for the hot-water bags (0.7 degree C/h) and the charcoal heater (0.6 degree C/h) tended to be higher than that for the chemical heating pads (0.2 degree C/h) and were significantly higher than that for spontaneous warming rate (0.1 degrees C/h, p < 0.05).
  
  
  CONCLUSIONS
  In subjects with shivering suppressed, greater sources of external heat were effective in attenuating core temperature afterdrop, whereas sustained sources of external heat effectively established core rewarming. Depending on the scenario and available resources, we recommend the use of charcoal heaters, chemical heating pads, or hot-water bags as effective means for treating cold patients in the field or during transport to definitive care.
authors.affiliation: Division of Surgery, Department of Surgery and Perioperative Sciences, Umeå University, Umeå, Sweden. lundgren.jp@hotmail.com
authors.forename: J Peter
authors.initials: JP
authors.lastname: Lundgren
authors.forename: Otto
authors.initials: O
authors.lastname: Henriksson
authors.forename: Thea
authors.initials: T
authors.lastname: Pretorius
authors.forename: Farrell
authors.initials: F
authors.lastname: Cahill
authors.forename: Gerald
authors.initials: G
authors.lastname: Bristow
authors.forename: Alecs
authors.initials: A
authors.lastname: Chochinov
authors.forename: Alexander
authors.initials: A
authors.lastname: Pretorius
authors.forename: Ulf
authors.initials: U
authors.lastname: Bjornstig
authors.forename: Gordon G
authors.initials: GG
authors.lastname: Giesbrecht
mesh_terms: D000328:Adult; D001831:Body Temperature / Q000502:physiology*; D004632:Emergency Medical Services; D004867:Equipment Design; D006801:Humans; D007035:Hypothermia / Q000628:therapy*; D008297:Male; D008350:Manitoba; D008991:Monitoring, Physiologic; D017694:Rewarming / Q000295:instrumentation*