Elsevier

Resuscitation

Volume 41, Issue 2, July 1999, Pages 105-111
Resuscitation

Forced air surface rewarming in patients with severe accidental hypothermia

https://doi.org/10.1016/S0300-9572(99)00069-6Get rights and content

Abstract

Methods of rewarming patients with severe accidental hypothermia remain controversial. This paper reports our experience with the use of forced air rewarming in patients with severe accidental hypothermia and a body core temperature below 30°C. Fifteen hypothermic patients (body core temperature 24–30°C) were successfully treated with forced air rewarming to a body core temperature above 35°C (mean rewarming rate 1.7°C/h, range from 0.7 to 3.4°C/h). An afterdrop phenomenon was not observed in any of the patients. Nine hypothermic patients (group 1) had no prehospital cardiac arrest, all nine were long-term survivors and made a full recovery. Six patients (group 2) had prehospital cardio circulatory arrest with restoration of spontaneous circulation. None of the group 2 patients survived long-term. Group 1 and group 2 patients did not differ in core temperature (26.6±1.6°C group 1 and 27.0±1.8°C group 2). Group 2 patients needed catecholamine support during rewarming more frequently (83 versus 22%) and had higher lactate levels and lower pH values at all points of observation. In conclusion our preliminary data indicate that forced air rewarming is an efficient and safe method of managing patients with severe accidental hypothermia. The poor outcome of patients with a history of prehospital cardiopulmonary resuscitation is probably due to irreversible ischaemic brain damage in primarily asphyxiated avalanche and near-drowning victims, rather than the consequence of the rewarming method used.

Introduction

Forced air rewarming is an established, simple and non invasive method of treating peri operative hypothermia associated with major surgery [1], [2]. Extensive data are available proving both its efficiency and safety in patients with mild to moderate hypothermia in the operating and recovery room [1], [2], [3], [4]. Although forced air rewarming is a potential therapeutic approach for patients with accidental hypothermia, only limited data are available [5], [6]. In a prospective, randomized study, Steele et al. [5] found the rewarming rate to be almost doubled in patients with accidental hypothermia rewarmed with forced air when compared to patients covered with warmed cotton blankets. In a more recent case series with three patients Koller et al. also found forced air rewarming to be a successful method of treating severely hypothermic patients, even two cases with a history of cardio-circulatory arrest [6]. Based on these data and our own successful management of eight hypothermic patients [7] we have routinely used forced air rewarming as the method of choice for rewarming patients with accidental hypothermia since 1995.

Despite the successful initial experience published in literature [5], [6], [7], there are still concerns about the routine use of forced air rewarming in hypothermic patients with a body core temperature below 30°C. Forced air rewarming is a form of active external rewarming which is considered inadequate for patients with a body core temperature below 30°C [8], [9], [10]. This is predominately due to the danger of an afterdrop in body core temperature caused by a shift of cold blood from the shell to the core of the body [8], [10], [11]. In addition, the preferential rewarming of the shell of the body may increase the workload of the hypothermic heart and induce vasodilation, both predisposing the hypothermic patient to a haemodynamic instability during rewarming [12].

Section snippets

Patients

The medical charts of all patients admitted to the emergency department of the University Hospital Innsbruck with accidental hypothermia between January 1995 and April 1998 were reviewed. Twenty-seven patients with severe accidental hypothermia and a body core temperature below 30°C were identified. Twelve of these patients were admitted in cardiac arrest and according to widely accepted recommendations [8], [9], [10] were rewarmed using extracorporeal circulation. The remaining 15 patients

Outcome

All 15 patients were successfully rewarmed to a body core temperature of 35°C with forced air rewarming. No other forms of rewarming were required. Mean rewarming rate was 1.7±0.7°C/h (0.7–3.4°C/h) [mean+S.D. (range)] and was not significantly different between group 1 [1.9±0.8°C/h (0.7–3.4°C/h)] and group 2 patients [1.5±0.3°C/h (1.2–1.5°C/h)]. Mean arterial pressure could be stabilized in all patients, although catecholamine support was necessary in seven of 15 patients. Catecholamine therapy

Discussion

We observed a mean rewarming rate of 1.7°C/h when using the forced air method. Steel et al. report a slightly higher rewarming rate of 2°C/h, whereas Koller et al. found a lower rewarming rate of 1°C/h [5], [6]. Some variability in the rewarming rates reported is also a common finding for other methods of rewarming [9], [10], [13]. A significant variation in the individual response to cooling and rewarming, an altered vasoconstrictor response in intoxicated patients, age, concomitant disease

References (28)

  • R. Koller et al.

    Deep accidental hypothermia and cardiac arrest-rewarming with forced air

    Acta Anaesth. Scand.

    (1997)
  • P. Mair et al.

    Accidental hypothermia

    Lancet

    (1995)
  • Emergency Cardiac Care Committee and Subcommittees, American Heart Association. Guidelines for cardiopulmonary...
  • G.M. Larach

    Accidental hypothermia

    Lancet

    (1995)
  • Cited by (82)

    • Hypothermic Cardiac Arrest – Retrospective cohort study from the International Hypothermia Registry

      2021, Resuscitation
      Citation Excerpt :

      Only 8 patients not in cardiac arrest received invasive internal rewarming as compared to 106 patients rewarmed externally. In view of the invasiveness of internal rewarming, the low rewarming rate of 1.3 °C/hour, compared to the good results obtained with external rewarming, use of internal rewarming methods should be reconsidered.44,45 Many clinicians have also observed lower rewarming rates with invasive internal methods compared to data from experimental studies.17

    View all citing articles on Scopus
    View full text