Hypothermia: Evaluation, Electrocardiographic Manifestations, and Management (original) (raw)

Diagnosis and treatment of hypothermia

American family physician, 2004

Although hypothermia is most common in patients who are exposed to a cold environment, it can develop secondary to toxin exposure, metabolic derangements, infections, and dysfunction of the central nervous and endocrine systems. The clinical presentation of hypothermia includes a spectrum of symptoms and is grouped into the following three categories: mild, moderate, and severe. Management depends on the degree of hypothermia present. Treatment modalities range from noninvasive, passive external warming techniques (e.g., removal of cold, wet clothing; movement to a warm environment) to active external rewarming (e.g., insulation with warm blankets) to active core rewarming (e.g., warmed intravenous fluid infusions, heated humidified oxygen, body cavity lavage, and extracorporeal blood warming). Mild to moderate hypothermia is treated easily with supportive care in most clinical settings and has good patient outcomes. The treatment of severe hypothermia is more complex, and outcomes ...

Induced Hypothermia to as Cold as 3°C in Humans: Forgotten Cases Rediscovered

High Altitude Medicine & Biology

Induced hypothermia to as cold as 3°C in humans: Forgotten cases rediscovered. High Alt Med Biol. 22:000-000, 2021. The lowest temperature from which humans can be successfully rewarmed from accidental hypothermia is unknown. The lowest published core temperature with survival from accidental hypothermia is 11.8°C. We recently reported a rediscovered case series of patients in whom profound hypothermia was induced for surgery. The patient in this case series with the lowest core temperature, 4.2°C, survived neurologically intact. We subsequently rediscovered several additional case series of induced hypothermia to core temperatures below 11.8°C. In one case series, at least one patient was cooled to 3°C. We do not know if any patient survived cooling to 3°C. As in the previous case series, the authors of the additional reports presented physiological data at various core temperatures, showing wide variations in individual responses to hypothermia. These data add to our understanding of the physiology of profound hypothermia. Although induced hypothermia for surgery differs from accidental hypothermia, survival from very low temperatures in induced hypothermia provides evidence that humans with accidental hypothermia can be resuscitated successfully from temperatures much lower than 11.8°C. We continue to advise against using core temperature alone to decide if a hypothermic patient in cardiac arrest has a chance of survival.

Accidental Hypothermia: 2021 Update

International Journal of Environmental Research and Public Health, 2022

Accidental hypothermia is an unintentional drop of core temperature below 35 °C. Annually, thousands die of primary hypothermia and an unknown number die of secondary hypothermia worldwide. Hypothermia can be expected in emergency patients in the prehospital phase. Injured and intoxicated patients cool quickly even in subtropical regions. Preventive measures are important to avoid hypothermia or cooling in ill or injured patients. Diagnosis and assessment of the risk of cardiac arrest are based on clinical signs and core temperature measurement when available. Hypothermic patients with risk factors for imminent cardiac arrest (temperature < 30 °C in young and healthy patients and <32 °C in elderly persons, or patients with multiple comorbidities), ventricular dysrhythmias, or systolic blood pressure < 90 mmHg) and hypothermic patients who are already in cardiac arrest, should be transferred directly to an extracorporeal life support (ECLS) centre. If a hypothermic patient a...

Physiological Changes in Subjects Exposed to Accidental Hypothermia: An Update

Frontiers in Medicine, 2022

BackgroundAccidental hypothermia (AH) is an unintended decrease in body core temperature (BCT) to below 35°C. We present an update on physiological/pathophysiological changes associated with AH and rewarming from hypothermic cardiac arrest (HCA).Temperature Regulation and MetabolismTriggered by falling skin temperature, Thyrotropin-Releasing Hormone (TRH) from hypothalamus induces release of Thyroid-Stimulating Hormone (TSH) and Prolactin from pituitary gland anterior lobe that stimulate thyroid generation of triiodothyronine and thyroxine (T4). The latter act together with noradrenaline to induce heat production by binding to adrenergic β3-receptors in fat cells. Exposed to cold, noradrenaline prompts degradation of triglycerides from brown adipose tissue (BAT) into free fatty acids that uncouple metabolism to heat production, rather than generating adenosine triphosphate. If BAT is lacking, AH occurs more readily.Cardiac OutputAssuming a 7% drop in metabolism per °C, a BCT decreas...

Untoward Effects in the Practice of Therapeutic Hypothermia: A Literature Update

Journal of Vascular Medicine & Surgery

Induction of mild TH causes sinus tachycardia in order to increase oxygenation of the vital organs. Compartmental shifting from peripheral vasoconstriction to the core vasculature follows. Vasoconstrictionrelated increase in systemic vascular resistance ensues which, in turn, result in an increase in mean arterial pressure concomitant with a drop in heart rate and cardiac output [12,13]. Hypothermia has a positive inotropic effect which results from improved left ventricular filling