Obesity, football, dog days and siriasis: a deadly combination

Solar Injury and Heat Illness

In brief Children are particularly susceptible to solar injury to the skin and eyes and to heat illness-heat cramps, heat exhaustion, and heatstroke. Because sunburn during childhood is linked to subsequent skin cancer, aggressive prevention through use of sunscreens and other protective measures is critical. Physicians should screen for risk factors for heat illness, such as hypohydration, obesity, poor conditioning, and certain illnesses. Heat illness can be effectively prevented through acclimation, proper hydration, and advance event planning.

Heat illness. Fluid and electrolyte issues for pediatric and adolescent athletes

The primary mechanism for maintaining normal body temperature during physical exercise in the heat is the evaporation of sweat. With profuse sweating, water loss far exceeds electrolyte loss. Rigorous exercise in the heat places the athlete at risk for thermoregulatory dysfunction from dehydration. Because children are inherently less efficient thermoregulators than adults, they are at even greater risk for heat illness. The three primary syndromes of heat illness are heat cramps, heat exhaustion, and heat stroke. Treatment of heat illness is based on reduction of body temperature and rehydration. Heat stroke is a true medical emergency with a high mortality rate; immediate reduction of body temperature is critical to the survival of these patients. Prevention of heat illness is based on reducing known risk factors. Physical activity should be modified in the face of high ambient temperature and humidity. The athlete should begin exercise well hydrated; frequent consumption of cold water during exercise decreases likelihood of significant dehydration. After exercise, the athlete should continue drinking to replace fluid losses. Clothing should be lightweight; the more skin exposed, the greater the available evaporative surface. A preseason conditioning program, when combined with an 8- to 14-day period of acclimatization, further reduces the risk of heat injury. Although athletes engaged in endurance sports may benefit from drinking carbohydrate/electrolyte-containing solutions, for the majority of young athletes, cold water remains the preferred choice for fluid replacement during exercise. The relatively greater body surface area of young athletes also places them at risk for hypothermia. Special attention should be given when these athletes are competing under cold environmental conditions.

The liver in fatal exertional heatstroke

We describe the chronology of hepatic histopathologic alterations in 50 cases of fatal exertional heatstroke related to military training. Five patients who died in the field demonstrated the earliest alterations: fatty change (sometimes microvacuolar), amitotic hepatocellular regeneration, accumulation of hemosiderin, and congestion. In addition, the sinusoids contained polymorphonuclear leukocytes, immature erythroid and granulocytic cells, megakaryocytes, and lymphocytes. Fibrin was not evident. The other 45 patients, who survived up to 8 days following hospitalization, also demonstrated these findings. Microvacuolar fatty change was common in this group of patients, and degenerated hepatocytes resembled Councilman bodies. Coagulative degeneration and submassive necrosis were uncommon. Of those surviving over 12 h, more than half had bile stasis (sometimes ductal), frequently associated with acute cholangitis and ductular proliferation. Regeneration and pigmentary alterations have not been recognized as early hepatic findings in heatstroke, nor have intrasinusoidal bone marrow elements, ductal bile stasis, and acute cholangitis been described. Possible pathogenic factors, other than hyperthermia and sequellae of shock, include obesity, recent illnesses and immunizations, bacterial toxemia, hemolysis, and bone marrow injury.

The histology of myocardium in malignant hyperthermia: a preliminary report of 11 cases

The preliminary results of a retrospective examination of the myocardium from 11 patients who responded to general anaesthesia with malignant hyperthermia are presented. Light-microscopical examination of the sections revealed no specific changes due to malignant hyperthermia. Contraction bands were demonstrated in 4 cases and it is concluded that the present investigation does not support the suggestion that a specific myofibrillar damage is responsbile for the arrhythmias seen in malignant hyperthermia.