Accidental profound hypothermia

Accidental hypothermia-an update : The content of this review is endorsed by the International Commission for Mountain Emergency Medicine (ICAR MEDCOM)

BACKGROUND

This paper provides an up-to-date review of the management and outcome of accidental hypothermia patients with and without cardiac arrest.

METHODS

The authors reviewed the relevant literature in their specialist field. Summaries were merged, discussed and approved to produce this narrative review.

RESULTS

The hospital use of minimally-invasive rewarming for non-arrested, otherwise healthy, patients with primary hypothermia and stable vital signs has the potential to substantially decrease morbidity and mortality for these patients. Extracorporeal life support (ECLS) has revolutionised the management of hypothermic cardiac arrest, with survival rates approaching 100 % in some cases. Hypothermic patients with risk factors for imminent cardiac arrest (temperature <28 °C, ventricular arrhythmia, systolic blood pressure <90 mmHg), and those who have already arrested, should be transferred directly to an ECLS-centre. Cardiac arrest patients should receive continuous cardiopulmonary resuscitation (CPR) during transfer. If prolonged transport is required or terrain is difficult, mechanical CPR can be helpful. Delayed or intermittent CPR may be appropriate in hypothermic arrest when continuous CPR is impossible. Modern post-resuscitation care should be implemented following hypothermic arrest. Structured protocols should be in place to optimise pre-hospital triage, transport and treatment as well as in-hospital management, including detailed criteria and protocols for the use of ECLS and post-resuscitation care.

CONCLUSIONS

Based on new evidence, additional clinical experience and clearer management guidelines and documentation, the treatment of accidental hypothermia has been refined. ECLS has substantially improved survival and is the treatment of choice in the patient with unstable circulation or cardiac arrest.

Disorders of Temperature Control: Hypothermia, Part III

Hypothermia, defined as a body core temperature below 35°C, results from exposure to cold, drugs, metabolic dysfunction, or nervous system or skin disorders. The diagnosis and clinical assessment of patients with hypothermia should be based on a thorough knowledge of the characteristic physiologic changes that accompany hypothermia and affect all organ systems. Morbidity and mortality resulting from hypothermia may be reduced when physicians anticipate the well-known complications of hypothermia and carefully rewarm the patient. The rate and method of rewarming must be individualized, taking into account available resources and the patient's cardiopulmonary status and underlying disease.

Management of profound hypothermia in children without the use of extracorporeal life support therapy

Profound hypothermia is managed more and more with extracorporeal life support technology, especially when a patient's circulation is compromised. Many centres do not have rapid access to this service, however, and are still dependent on active internal rewarming techniques--eg, peritoneal and pleural lavage. Such interventions are invasive, and associated with inherent risk. Here, we report our successful experience with an active external rewarming technique in children with profound hypothermia (core temperature <20 degrees C).

Hypothermia in trauma patients

Hypothermia occurs commonly in severely injured patients and is associated with a high mortality rate. It perturbs the normal homeostatic response to injury and affects multiple organ systems and physiologic processes. In trauma patients, hypothermia-induced coagulopathy often leads to marked bleeding diathesis and frequently provides a challenge for the surgeon. Once hypothermia occurs, it is often difficult to correct. Efforts to prevent and treat hypothermia in trauma patients should be instituted in the field and continued as an integral part of the resuscitation process. Hospital personnel and physicians at various levels caring for trauma patients from the initial injury and thereafter should bear in mind that a patient's temperature is as important as any other vital sign. Appropriate measures for preventing and treating hypothermia should be instituted promptly and tended to with utmost vigilance.

[Accidental deep hypothermia and circulatory arrest. Treatment with extracorporeal circulation]

A 27-year old female was discovered at 4 a.m. lying in a wet field, the ambient temperature being of 4 degrees C. Her rectal temperature had fallen to 19 degrees C. She was comatose and failed to respond to noxious stimuli. Her pupils were dilated and fixed. Her respiratory rate was reduced to three to four breaths per min. Her blood pressure was not measurable and neither femoral or carotid pulse could be detected. The heart was in sinus rhythm with a rate of 40 b X min-1. During her transfer to hospital, she was ventilated with oxygen, a tidal volume of 300 ml and a rate of 10 b X min-1. On arrival in the emergency room, a short period of ventricular fibrillation preceded cardiac arrest. Cardiac massage and sodium bicarbonate infusion were continued during the transfer of the patient to the operating theatre. A femoro-femoral cardiopulmonary bypass was started with a bloodless priming, 3 mg X kg-1 heparin and a flow of 3,000 to 3,500 ml X min-1. Mean arterial pressure was maintained between 65 and 85 mmHg; cardiac massage was discontinued during the bypass. Within 50 min, ventricular fibrillation appeared, rectal temperature had increased to 33 degrees C. Electrical defibrillation (300 J) was successful. Cardiopulmonary bypass was stopped after 63 min. The postoperative course was uneventful, apart from transient pulmonary oedema. At the time of discharge, a week later, no loss of intellect or change in behaviour could be perceived.(ABSTRACT TRUNCATED AT 250 WORDS)

Accidental hypothermia

Knowledge of the effects of hypothermia has increased greatly over the past 25 yr. Thousands of patients have been cooled intentionally in the operating room, and hundreds of thousands of living hearts have been temporarily stopped by cold cardioplegia and restarted without difficulty or apparent ill-effect. Yet in spite of the acquisition of this vast body of clinical experience an aura of mystery stills surrounds the patient who becomes hypothermic accidentally. The best treatment in any particular case is not always clear, and published accounts do not always give the impression that the hypothermic patient is treated with the same rational approach with which other sick and comatose patients are treated. In summarizing, therefore, conclusions that might be reached from reviewing past experience several important points emerge. The severely hypothermic patient should be treated in an intensive care unit where appropriate monitoring of temperature, cardiovascular function and respiratory function are available, and where full respiratory support including assisted ventilation can be given. The final outcome depends upon the etiology. The young healthy victim of exposure has a good chance of surviving. The patient poisoned by alcohol or barbiturates has a good chance of surviving provided the level of intoxication is not itself lethal. The elderly without severe underlying disease have a good chance of surviving. The patient with severe underlying disease of the endocrine, cardiovascular or neurologic system probably has, at best, a 50% chance of surviving and, at worst, a chance of only 10-20%, depending upon the associated disease. There is no statistical evidence that any one method of rewarming is significantly better than any other. But there is anecdotal evidence that in the absence of full monitoring and support systems slow rewarming is safer than over-energetic external rewarming. Internal rewarming, peritoneal dialysis, hemodialysis, inhalation of warmed oxygen and extracorporeal circulation are effective in severe cases and can be used with safety. The causes of, and triggering mechanism for, ventricular fibrillation are still largely unknown but the onset of ventricular fibrillation in a very cold patient may often be an irreversible complication. The place of modern anti-arrhythmic drugs in the prevention and management of this complication has yet to be elucidated. Cardiopulmonary resuscitation is difficult in profoundly hypothermic patients but should be maintained until a body temperature of 30 degrees C has been achieved.(ABSTRACT TRUNCATED AT 400 WORDS)

Accidental hypothermia: report of a case following alcohol and barbiturate overdose

A case of accidental hypothermia due to overdose of alcohol and barbiturates combined with exposure to cold is described and management is discussed.