Severe hypothermia

Coagulation defects have been noted with severe hypothermia. These defects include platelet dysfunction, increased fibrinolytic activity, and decreased enzymatic activity necessary for clotting to occur (48,49). However, even mild surface cooling may produce a reversible platelet defect (48,50,51). Mild hypothermia typically reduces metabolism and hepatic clearance of various anesthetic agents and other medications (52). This must be taken into consideration when formulating an anesthetic plan for the hypothermic patient. 

A neonate had severe hypothermia after antenatal exposure to haloperidol (43). He weighed 3710 g at birth and did not need resuscitation his axillary temperature was 35° C and he had severe generalized hypotonia. His temperature rose to 36.5°C after 6 hours of rewarming with an overhead radiant heater. 

Mohan MS, Patole SK, Whitehall JS. Severe hypothermia in a neonate following antenatal exposure to haloperidol. J Paediatr Child Health 2000 36(4) 412-3. 

In a 30-day study of the administration of L-selenomethionine to long-tailed macaques, severe hypothermia was observed in two of five animals administered 0.12 mg selenium/kg/day, but not in any of the eight animals receiving <0.08 mg selenium/kg/day (Cukierski et al. 1989). However, the increased incidence of hypothermia was not statistically significant. Following 1 week of treatment, all animals administered L-selenomethionine, including the two macaques treated with 0.01 mg selenium/kg/day, exhibited increased drowsiness and lethargy (Cukierski et al. 1989). 

Severe hypothermia (temperature < 28-30°C) may cause intractable ventricular fibrillation and cardiac anest. This may occur abmptly, such as when the patient is moved or rewamned too quickly or when CPR is performed. 

Answer (D) If the mountain climber s body did not immediately replenish the lost heat her body temperature would drop by more than ten degrees, ((body) = 36.6 - 10.5 = 25.1°C. If her metabolism did not switch into high gear - long before her temperature drops several degrees Celsius - she would die. To keep the temperature of her body about constant she would have to burn, fast, a lot of food and reserve nutrients in the body. If this has happened as described the mountain climber would suffer from a severe hypothermia and possibly experience disruption of some bodily functions. You may now appreciate the fact we all take for granted today our clothes are coated with water-repellant materials. 

Drug interactions anticonvulsants (phenytoin, barbiturates, carbamazepine) increase the risk of hepatotoxicity by increasing conversion of acetaminophen to toxic metabolites. Isoniazide also increases risk of acetaminophen hepatotoxicity. Acetaminophen may enhance the anticoagulant effect of warfarin with daily doses > 1.3 g for > 1 week. Phenothiazines may increase risk of severe hypothermia with acetaminophen. Cholestyramine resin may decrease the absorption of acetaminophen. 

Hypothermia is the condition of reduced temperatures. Most cases of hypothermia develop when air temperatures are between 2° and 10°C (30° to 50°F). Uncontrollable shivering and the sensation of cold lead to decreased and/or irregular heartbeats, cool skin, impaired judgment and mental functioning, low blood pressure, and fatigue. Severe hypothermia can result in death. 

Normal body temperature is around 37 °C. If core temperature falls below 35 C, a person experiences mild hypothermia. The patient normally feels intense cold and suffers bouts of shivering. If the core temperature falls below 32 C the patient suffers severe hypothermia, which may cause cognitive impairment or even comma. Hypothermia can be as a result of environmental exposure to the cold. Many elderly patients that live alone and suffer falls can often be left on the floor for some time before being discovered, many of these patients develop hypothermia while they await discovery. Hypothermia is easily diagnosed by the use of a thermometer. There are however several key features which are also seen on the 12-lead ECG. These include ... 

T. Sakuma, K. Suzuki, M. Usuda, M. Handa, G. Okaniwa, T. Nakada, S. Fujimura and M. A. Matthay, Preservation of alveolar epithelial fluid transport mechanisms in rewarmed human lung after severe hypothermia,/. Appl Physiol, 1996,80,1681-1686. 

In the hypothermic patient, other disturbances are not properly corrected and collapse, haemorrhage and metabolic problems may add to the severity of the condition. Six cases of severe hypothermia, one of them fatal, have been reported, due to rapid infusion of blood which had not been warmed sufficiently prior to administration (7, 8 ). In these cases, the extent of the area of surgery had been large and the operating room had been cooled by air conditioning. The environmental temperature and the central temperature of the body should be watched with care. 

Schwab S, Schwarz S, Spranger M, Keller E, Bertram M, Hacke W. Moderate hypothermia in the treatment of patients with severe middle cerebral artery infarction. Stroke 1998 29 2461-2466. 

Schwab et al. Stroke 1999 30(5) 1153 Prospective pilot study moderate hypothermia in severe stroke and ICP 25 of 25 tx with hypothermia Hypothermia to 33-34°C with cooling blankets in pts with compete MCA infarct and ICP monitor 44% mortality, all by herniation after secondary rise in ICP after rewarming period. Good control of ICP during hypothermia period. Forty percent rate of pneumonia... 

Georgiadis D, Schwarz S, Aschoff A, Schwab S. Hemicraniectomy and moderate hypothermia in patients with severe ischemic stroke. Stroke 2002 33(6) 1584-1588. 

At blood levels of 0.02 g%-0.09 g% (4.34 to 19.5 mmol/L) may see some prolonged reaction time and muscular incoordination At blood levels from 0.1 g%-0.2g% (21.7 to 43.4 mmol/L) may see obvious prolonged reaction time, obvious incoordination and ataxia, and mental impairment At blood levels from 0.2 g% to 0.3g% (43.4 to 65.1 mmol/L) marked ataxia, some dysarthria, and possible nausea and vomiting At blood levels from 0.3 g% to 0.4g% (61.5 to 86.8 mmol/L) severe dysarthria, amnesia, and hypothermia... 

Carbamyl phosphate synthetase deficiency. Carbamyl phosphate synthetase deficiency is rare. Neonates quickly develop lethargy, hypothermia, vomiting and irritability. The hyperammonemia typically is severe, even exceeding 1 mmol/1. Occasional patients with a partial enzyme deficiency have had a relapsing syndrome of lethargy and irritability upon exposure to protein. Brain damage can occur in both neonatal and late-onset groups. 

Exercise is not without risks these include sudden cardiac death, hyperthermia, hypothermia, hypoglycaemia, hypo-natraemia, a reduction in the effectiveness of the immune system, overuse injury and interference in the reproductive system in females. Whether severe physical activity affects the reproductive system in males is sometimes discussed but these are no reports in the scientific literature. 

The symptoms of overdose are to some extent predictable from the antimuscarinic and adrenolytic activity of these drugs. Excitement and restlessness, sometimes associated with seizures, and rapidly followed by coma, depressed respiration, hypoxia, hypotension and hypothermia are clear signs of TCA overdose. Tachycardia and arrhythmias lead to diminished cardiac function and thus to reduced cerebral perfusion, which exacerbates the central toxic effects. It is generally accepted that dialysis and forced diuresis are useless in counteracting the toxicity, but activated charcoal may reduce the absorption of any unabsorbed drug. The risk of cardiac arrhythmias may extend for several days after the patient has recovered from a TCA overdose. 

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