HEAT STROKE
When the temperature exceeds 40 ° C, the condition of heat stroke will occur and will central nervous system dysfunction is severe. Two other related conditions that are caused by exposure to heat cramps and heat exhaustion.
In the desert country with frequent outdoor physical activity in these cases. When pilgrims outdoor activity in place. Circumstances Heat cramps - muscle pains after the heat energy in hot environments, usually are associated with a deficit of salt. examples such as exertional rhabdomyolysis. The last condition, which may also be a complicating factor in heat stroke, involving acute muscle injury due to severe exertional effort beyond the limits that have been ditelorir individuals. This often results in myoglobinuria, which can affect kidney function, especially when heat stroke occurs when patients. There is a term Heat exhaustion - is made up of fatigue, muscle weakness, tachycardia, postural syncope, nausea, vomiting, and urge to defecate caused by dehydration and hypovolemia from heat stress. Although the normal body temperature in heat exhaustion, there is a relationship between the syndrome and heat stroke.
Actually, the Heat stroke, a result of an imbalance between heat production and heat dissipation, heat stroke can kill. heat stroke that most often affects young people with physical activity. in hot environments, usually without adequate training and knowledge. heat stroke is a disease of sedentary elderly or sick heart of the system can not adapt to the stress of hot environments, although not active. heat stroke in the elderly can be predicted when the ambient temperature exceeds 32.2 ° C and relative humidity 50-76%.
heat elimination from the skin by radiation, conduction, convection, and evaporation. When the temperature rises, heat loss by the first three distracted; loss by evaporation is blocked by high relative humidity. Some factors predisposing to heat accumulation dermatitis; use of phenothiazines, beta-blockers, diuretics, or anticholinergics, intercurrent fever from other diseases: obesity, alcohol, and heavy clothing. Cocaine and amphetamines may increase metabolic heat production.
Mechanism of heat damage to parenchymal organs and blood vessels. Central nervous system is extremely vulnerable, and cellular necrosis was found in the brains of people who died from heat stroke. Hepatocellular and renal tubular damage seen in severe cases. Subendocardial damage and transmural infarcts are sometimes found in fatal cases. disseminated intravascular coagulation are common, aggravating the injury in all organ systems and predisposing bleeding complications.
Clinical symptoms
A. Symptoms and Signs
Heat stroke should be suspected in anyone who develops a sudden coma in a hot environment. If the patient's temperature is above 40 ° C (range: 40-43 ° C), a definitive diagnosis of heat stroke. Measurement of rectal body temperature should be done. A prodrome including dizziness, headache, nausea, chills and goose bumps from the chest and arms appear occasionally but not commonly. In most cases, patients were recalled after a warning symptoms except weakness, fatigue, or dizziness. Confusion, aggressive behavior, or fainting may precede coma. Seizures may occur after admission to hospital.
Pink or pale skin and sometimes, strangely, dry and hot, dry skin in the presence of hyperpyrexia heat stroke is almost pathognomonic. Excessive sweating is usually on the runners and other athletes are exposed to heat stroke. Heart rate ranged from 140/min to 170/min; central venous pressure or pulmonary wedge high, and in some cases of low blood pressure. Hyperventilation can be reached 60/min and may cause respiratory alkalosis. pulmonary edema and bloody sputum may develop in severe cases. Jaundice is often the first few days after onset of symptoms.
Dehydration, which can produce the same system as the central nervous symptoms of heat stroke, an irritating factor in approximately 15% of cases.
B. Laboratory
There is no pattern to the changing characteristics of the electrolytes: sodium serum concentrations may be normal or high, and potassium concentrations are usually low on admission or at some point during resuscitation. General hypocalcemia, and hipofosfatemia may occur. In the first few days, AST, LDH, and CK may increase, especially in exertional heat stroke. Alkalosis may follow hyperventilation; acidosis can be caused by lactic acidosis or acute renal failure. Proteinuria and granular cells and casts seen in urine specimens of red were collected immediately after diagnosis. If urine is dark red or brown, it may contain myoglobin. Blood urea nitrogen and serum creatinine increased transiently in most patients and continued to go up if kidney failure develops. Hematological findings may be normal or may be typical of disseminated intravascular coagulation (ie, low fibrinogen, increased fibrin split products, prothrombin time and partial thromboplastin slow, and decreased platelet count).
Prevention
For the most part, heat stroke in military recruits and athletes in training can be prevented by following a schedule of graduation requirements that enable improved performance of acclimatization for 2-3 weeks. Heat generated by exercise is dissipated by increased cardiac output, vasodilation in the skin, and increased sweating. With acclimatization there is an increased efficiency to the working muscles, improve cardiac muscle performance, expanded extracellular fluid volume, the output is greater than a certain amount of sweat to work, lower salt content of sweat, and a lower central temperature for a certain amount of work.
Access to drinking water should be restricted during vigorous physical activity in hot environments. Free water is better than a solution containing electrolytes. Most of the training regimen should not include the additional use of salt tablets, because the salt is enough (10-15 g / h) will be consumed with food to meet the electrolytes lost in sweat and since hypernatremia can develop if swallowed salt tablets are not taken with enough water. Clothing and protective equipment should be alleviated as the production of heat and air temperatures rise, and strenuous exercise should not be scheduled at the hottest time of the day, especially at the beginning of the training schedule. Long distance running with an open competition, which attracted a beginner runner, should be held in late summer or autumn, when the heat acclimatization is more likely to occur, and must start before 8 am or after 6 pm.
management
The first step after step, namely ABC Patients should be cooled quickly. The most efficient method is to drive the evaporative heat loss by the patient by spraying water at 15 ° C and fanned by the warm air. Soaking in a tub of ice water or use ice packs are also effective but causes vasoconstriction and shivering skin and make patient monitoring more difficult. Monitor the temperature of the rectum often. To avoid overshooting the end point, strong cooling should be discontinued when the temperature reached 38.9 ° C. Shivering should be controlled with parenteral phenothiazines. Oxygen should be given, and if PaO2 falls below 65 mm Hg, tracheal intubation was performed to control ventilation. Fluid, electrolyte, and acid-base balance should be controlled with frequent monitoring. Intravenous fluid administration should be based on central venous pressure or pulmonary artery wedge, blood pressure and urine output; overhydration should be avoided. On average, approximately 1400 mL of fluid required in the first 4 hours of resuscitation. Intravenous mannitol (12.5 g) can be given early if myoglobinuria is present. Kidney failure may require hemodialysis. Disseminated intravascular coagulation may require treatment with heparin. Digitalis and sometimes inotropic agents (eg, isoproterenol, dopamine) may be indicated for cardiac insufficiency, which should be suspected when persistent hypotension after hypovolemia has been corrected.
Prognosis
poor prognosis when the body temperature of 42.2 ° C or more, coma lasting more than 2 hours, shock, hyperkalemia, and AST more than 1000 units / L during the first 24 hours. The death rate is about 10% in patients who are diagnosed correctly and treated promptly. Death within the first few days is usually due to brain damage; Death comes perhaps from hemorrhage or perhaps because of the heart, kidney, or liver failure.
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