Forced-air rewarming in -20 degrees C simulated field conditions

Wilderness Medical Society Clinical Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2019 Update

To provide guidance to clinicians, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for the out-of-hospital evaluation and treatment of victims of accidental hypothermia. The guidelines present the main diagnostic and therapeutic modalities and provide recommendations for the management of hypothermic patients. The panel graded the recommendations based on the quality of supporting evidence and a balance between benefits and risks/burdens according to the criteria published by the American College of Chest Physicians. The guidelines also provide suggested general approaches to the evaluation and treatment of accidental hypothermia that incorporate specific recommendations. This is the 2019 update of the Wilderness Medical Society Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia: 2014 Update.

Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia

Accidental hypothermia is an unintentional drop in core temperature to 35°C or below. Core temperature is best measured by esophageal probe. If core temperature cannot be measured, the degree should be estimated using clinical signs. Treatment is to protect from further heat loss, minimize afterdrop, and prevent cardiovascular collapse during rescue and resuscitation. The patient should be handled gently, kept horizontal, insulated, and actively rewarmed. Active rewarming is also beneficial in mild hypothermia but passive rewarming usually suffices. Cardiopulmonary resuscitation should be performed if there are no contraindications to resuscitation. CPR may be delayed or intermittent.

Wilderness Medical Society practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia: 2014 update

To provide guidance to clinicians, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the out-of-hospital evaluation and treatment of victims of accidental hypothermia. The guidelines present the main diagnostic and therapeutic modalities and provide recommendations for the management of hypothermic patients. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks/burdens according the criteria published by the American College of Chest Physicians. The guidelines also provide suggested general approaches to the evaluation and treatment of accidental hypothermia that incorporate specific recommendations. This is an updated version of the original Wilderness Medical Society Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia published in Wilderness & Environmental Medicine 2014;25(4):425-445.

Wilderness Medical Society practice guidelines for the out-of-hospital evaluation and treatment of accidental hypothermia

To provide guidance to clinicians, the Wilderness Medical Society (WMS) convened an expert panel to develop evidence-based guidelines for the out-of-hospital evaluation and treatment of victims of accidental hypothermia. The guidelines present the main diagnostic and therapeutic modalities and provide recommendations for the management of hypothermic patients. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks/burdens according the criteria published by the American College of Chest Physicians. The guidelines also provide suggested general approaches to the evaluation and treatment of accidental hypothermia that incorporate specific recommendations.

Hypothermia during laparotomy can be prevented by locally applied warm water and pulsating negative pressure

BACKGROUND

Conflicting results have been obtained when using heat and constant negative pressure applied to the arm to induce re-warming in patients with mild hypothermia due to surgery. We hypothesized that pulsating negative pressure would increase skin blood flow and thus heat transfer. The purpose of this study was to compare a new method of applying heat and pulsating negative pressure to the skin with conventional forced-air warming for preventing perioperative hypothermia.

METHODS

Twenty patients undergoing prolonged laparotomy for gastric surgery were randomized into two groups. One group (SM) received hospital standard method: forced-air warming, 43 degrees C (Bair Hugger) on the thoracic and upper arm surface. The other group (NM) received the new method: warm water and pulsating negative pressure treatment applied in a transparent acrylic cylinder (50 x 16 cm) on one arm. The cylinder was circulated with water at 42.5 degrees C, leaving an air pocket inside the device. Pulsating pressure between 0 and -40 mm Hg was generated in the air pocket inside the cylinder.

RESULTS

Two groups of 10 patients were studied. Warming was started shortly after induction of general anaesthesia. The two methods performed similarly during the first 60 min, with a mean 0.7 degrees decrease in core temperature. The tympanic temperature curve in NM group then increased and returned to baseline (37 degrees C) by 120 min. The temperature of SM group increased more slowly, reaching 36 degrees C by 120 min (P < 0.05).

CONCLUSION

Warm water and pulsating negative pressure was significantly better at treating hypothermia during laparotomy than forced-air warming.