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A torso model comparison of temperature preservation devices for use in the prehospital environment
  1. Michele Zasa1,2,
  2. Neil Flowers1,
  3. David Zideman1,
  4. Timothy J Hodgetts1,
  5. Tim Harris1,3
  1. 1East Anglian Air Ambulance, Helicopter Emergency Medical Service, Hangar D, Gambling Close, Norwich Airport, Norwich, UK
  2. 2Clinica Mobile nel Mondo, World Motorbike Championships (MotoGP & WSBK) Medical Division, Parma, Italy
  3. 3Academic Department Emergency Medicine, Queen Mary University London and Barts Health NHS Trust, London, UK
  1. Correspondence to Professor Tim Harris, East Anglian Air Ambulance, Helicopter Emergency Medical Service, Hanger D, Gambling Close, Norwich Airport, Norwich NR6 6EG, UK; tim.harris{at}


Background Hypothermia is an independent predictor of increased morbidity and mortality in patients with trauma. Several strategies and products have been developed to minimise patients’ heat loss in the prehospital arena, but there is little evidence to inform the clinician concerning their effectiveness.

Methods We used a human torso model consisting of two 5.5-litre fluid bags to simultaneously compare four passive (space blanket, bubble wrap, Blizzard blanket, ambulance blanket) and one active (Ready-Heat II blanket) temperature preservation products. A torso model without any temperature preservation device provided a control. For each test, the torso models were warmed to 37°C and left outdoors. Core temperatures were recorded every 10 min for 1 h in total; tests were repeated 10 times.

Results A significant difference in temperature was detected among groups at 30 and 60 min (F (1.29, 10.30)=103.58, p<0.001 and F (1.64, 14.78)=163.28, p<0.001, respectively). Mean temperature reductions (95% CI) after 1 h of environmental exposure were the following: 11.6 (10.3 to 12.9) °C in control group, 4.5 (3.9 to 5.1) °C in space blanket group, 3.6 (3 to 4.3) °C in bubble-wrap group, 2.1 (1.7 to 2.5) °C in Blizzard blanket group, 6.1 (5.8 to 6.5) °C in ambulance blanket group and 1.1 (0.7 to 1.6) °C in Ready-Heat II blanket group.

Conclusions In this study, using a torso model based on two 5 L dialysate bags we found the Ready-Heat II heating blanket and Blizzard blanket were associated with lower rates of heat loss after 60 min environmental exposure than the other devices tested.

  • Trauma
  • emergency ambulance systems
  • environmental medicine, hypothermia
  • hypothermia
  • prehospital care

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