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Dangerous heat injuries need special attention
At Carondelet St. Mary's Hospital in Tucson, AZ, ED nurses often see the life-threatening consequences of heat stroke and hyperthermia, says Diana Platt Lopez, RN, BSN, CCRN, CEN, clinical educator for the emergency center.
"Every year we see multiple patients, often our desert crossers, who are brought here in extremis," says Lopez. "Sometimes they survive intact, but other times they survive after a long hospital course including rhabdomyolysis and organ failure."
Hyperthermic patients who present to the ED with higher initial temperatures, hypotension, or a low Glasgow Coma Scale score are more likely to die, says a new study.1 Researchers looked at 52 patients who came to the ED at Banner Good Samaritan Regional Poison Control Center in Phoenix, from 2003 to 2005.
Initial management of the severely hyperthermic patient starts with airway, breathing, and circulation, and correction of urgent problems including hypoxemia, severe hyper/hypokalemia, and acidosis, says Lopez. (See steps taken by ED nurses.) "Patients can developed rebound hyperthermia in three to six hours, and it is treated the same way as initial treatment," she adds.
Five steps to better care
To improve care of patients with heat injuries, do the following:
• Understand the different types of heat stroke.
Heat stroke is defined as a core body temperature in excess of 105° F, with associated central nervous system dysfunction in the presence of environmental heat loads that cannot be dissipated, says Steve Rasmussen, RN, CEN, clinical coordinator for the ED at Virginia Commonwealth University Medical Center in Richmond. Frequently encountered complications include acute respiratory distress syndrome, hypoglycemia, multiorgan system failure, disseminated intravascular coagulation (DIC), seizures, and rhabdomyolysis, he says.
Exertional heat stroke generally occurs in healthy persons who engage in strenuous activities during hot temperatures, says Rasmussen. Symptoms may include cutaneous vasodilation, tachypnea, altered level of consciousness, seizures, excessive bleeding due to DIC, and/or rales due to noncardiac pulmonary edema, he says.
"Skin may be dry or moist, depending on underlying medical conditions and hydration status, and the speed at which the heat stroke developed," says Rasmussen. Effects of heat stroke may include the following, says Lopez:
— neurologic dysfunction due to metabolic disturbances leading to seizure activity and changes in level of consciousness and uncoordinated movements;
— compromise of cardiovascular system due to dehydration and vasoconstriction that limits effectiveness of heat loss mechanisms;
— tachyarrhythmias such as atrial fibrillation and supraventricular tachycardia;
— hypotension due to shunting of the blood to the periphery to aid with heat dissipation.
— rhabdomyolysis due to breakdown of skeletal muscle and the release of myoglobin leading to acute/ chronic renal failure, coagulopathy, and DIC;
— conduction defects such as prolonged QT interval and nonspecific ST changes. "The patient develops lactic acidosis and hypovolemic shock," says Lopez. "The risk of gut ischemia due to re-distribution of the blood to the periphery is significant."
• Identify factors that decrease the patient's ability to disperse heat.
Underlying chronic conditions may impair thermoregulation, such as cardiovascular disease, extreme age, obesity, use of drugs, and neurologic or psychiatric disorders, says Rasmussen. Diuretics, beta-blockers, and phenothiazines impair thermoregulation, and dietary supplements containing ephedra, cocaine, ecstasy, amphetamines, and benztropine increase metabolic heat production, says Lopez.
• Use appropriate methods to cool patients.
The goal is to decrease the core temperature to less than 36.9° C within 30 minutes, says Lopez. "This improves survival and minimizes end organ damage," she says. "Lactated Ringer's is not a good choice because it may worsen lactic acidosis."
Evaporation cooling is considered the modality of choice because it is effective, noninvasive, and easily preformed, says Rasmussen. The naked patient is sprayed with lukewarm water and placed under fans, and benzodiazepines or lorazepam may be used to suppress shivering, he explains. "Ice packs to the axillae, neck, and groin are effective but poorly tolerated in conscious alert patients," he says. "Cold oxygen, cooling blankets, and cold [intravenous] fluid can be used."
Cold peritoneal lavage also can be used but it is an invasive technique and not well tolerated in awake patients, says Rasmussen. "Alcohol sponge baths should be avoided because large amounts of the drug may be absorbed and produce toxicity," he says. "Antipyretic agents should not be used since the underlying cause does not involve the hypothalamus."
• Don't overlook hyperthermia.
Hyperthermia can mimic other conditions such as abdominal and neurological illnesses, says Frank LoVecchio, DO, MPH, the study's author and research director in the Department of Emergency Medicine at Maricopa Medical Center in Phoenix. "Even if the patient's temperature is not elevated, it may have been prior," says LoVecchio. To avoid overlooking hyperthermia, take a thorough history, he recommends. "Be aware of what occurred prior to the event, and remember that old and very young patients are more prone to the disorder," LoVecchio says
• Don't miss atypical symptoms.
Not all patients present with classic signs of heat stroke, warns Toni Colvard, RN, ED manager at Atlanta Medical Center. "They either may not feel it is heat related if the symptoms are not extreme, or confuse it with heat exhaustion which is less serious," says Colvard. "Either way, nurses may not act upon it aggressively or quickly enough."
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