Diseases » Fever

Hyperthermia

Hyperthermia: Excerpt from Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series

Hyperthermia, also known as heat syndrome, refers to an elevation of the core body temperature above normal. (See Signs and symptoms of heat syndromes.) It results when environmental and internal factors increase heat production or decrease heat loss beyond the body’s ability to compensate. Hyperthermia affects males and females equally; however, incidence increases among elderly patients and neonates during excessively hot days. Risk factors for hyperthermia include obesity, salt and water depletion, alcohol use, poor physical condition, age, and socioeconomic status.

A temperature between 99º and 102º F (37.2º and 38.9º C) is considered mild hyperthermia; a temperature between 102º and 105º F (38.9º and 40.6º C) is considered moderate hyperthermia. A temperature of 105º F (40.6º C) or above is considered critical hyperthermia and represents an emergency — particularly if the temperature rises rapidly or stays elevated for a prolonged period.

Act Now: For critical hyperthermia, immediate action should include providing supplemental oxygen and preparing the patient for endotracheal intubation and mechanical ventilation, if necessary. The goal is to reduce the patient’s temperature, but not too rapidly; rapid reduction can lead to vasoconstriction, which can lead to shivering. Administer diazepam or chlorpromazine to control shivering. Shivering must be treated because it increases metabolic demands and oxygen consumption. Continuous cardiac monitoring will be instituted and the patient will be monitored for arrhythmias. Prepare the patient for pulmonary artery catheter insertion to monitor the body’s core temperature. Closely observe the patient’s vital signs and level of consciousness. Administer fluids and replace electrolytes, as ordered. Remove the patient’s clothing and apply cool water to the skin, and then fan the patient with cool air.

In mild and moderate hyperthermia, provide a cool, calm environment and allow the patient to rest. Encourage the oral intake and administration of I.V. fluids. Replace electrolytes, as necessary.

Assessment

History

Ask the patient about the onset and duration of the fever. Ask the patient to describe the pattern of the fever. Did the temperature rise progressively or did it rise, disappear, and then reappear? Does he have accompanying symptoms, such as chills, headache, fatigue, diarrhea, or pain? Has the patient recently had an infection or exposure to an organism or someone else who was ill? Ask the patient whether he was exposed to high temperatures for a prolonged period of time. Ask about his work environment and water consumption while working. Has the patient experienced unusual physical or emotional stress recently? Ask if he has had any burns or trauma, undergone surgery under general anesthesia, or received a blood transfusion. Does the patient have a history of endocrine dysfunction or malignant hyperthermia? Is he taking thyroid medication? Ask the patient about other medications that disrupt thermoregulatory function such as salicylates as well as drugs that impair sweating, such as antibiotics, anticholinergics, monoamine oxidase inhibitors, or phenytoin.

Physical examination

Perform a physical examination based on the patient’s health history. Note the rate and depth of the patient’s breathing and any changes from normal respiratory patterns. Inspect the skin color and temperature. Check the skin turgor and monitor for diaphoresis. Assess for signs of trauma or needle marks on the arms or legs. Inspect for shivering of the body or flushing of the face. Assess his oral mucosa for lesions or signs of dehydration. Assess the patient’s mental status and be alert for signs of malaise, fatigue, restlessness, or anxiety. Auscultate lung fields and the abdomen. Monitor vital signs and the cardiac rate, rhythm, and intensity. Keep in mind that palpating the thyroid gland of a patient with hyperthyroidism can induce thyrotoxicosis.

Pediatric pointers

Rarely, maternal thyrotoxicosis may be passed to the neonate, resulting in hyperthermia. More commonly, acquired thyrotoxicosis appears between ages 12 and 14, although this too is infrequent. Dehydration will also make a child sensitive to excessive heat.

Medical causes

Infection and inflammatory disorders

Depending on the specific disorder, the temperature elevation may be insidious or abrupt. It can be a prodromal symptom and is often accompanied by chills, goose bumps, generalized symptoms of fatigue, headache, weakness, anorexia, malaise, and possibly, pain. If the temperature is high, you may find that the patient, particularly an elderly patient, is disoriented and confused. Other associated signs and symptoms depend on the disease and can involve any body system. The patient’s history may include exposure to an infectious agent, travel to an endemic area, or exposure to the animal or insect vector of an infectious organism. Or his recent history may include a blood transfusion, surgery, trauma, or burns.

Malignant hyperthermia

Rapid temperature increases occur at a rate of about 2º F (1.1° C) every 15 minutes to as high as 109.4° F (43° C). Usually the rise is preceded by skeletal muscle rigidity, cardiac arrhythmia, tachycardia, and tachypnea. The patient’s history will include exposure to inhalant anesthesia, particularly halothane, or muscle relaxants, particularly succinylcholine, which can trigger malignant hyperthermia in patients with the inherited trait. Other predicting factors in susceptible persons include trauma, exercise, exposure to high environmental temperatures, and infection.

Neuroleptic malignant syndrome

Neuroleptic malignant syndrome is marked by an explosive onset of hyperthermia accompanied by muscle rigidity, altered level of consciousness, cardiac arrhythmias, tachycardia, wide fluctuations in blood pressure, postural instability, dyspnea, and tachypnea. The patient history will include use of neuroleptic drugs such as haloperidol, chlorpromazine, thioridazine, or thiothixene.

Thermoregulatory dysfunction

With thermoregulatory dysfunction, the patient’s temperature rises suddenly and rapidly. The temperature then stays at 105° F to 107° F (40.6° C to 41.7° C). Assessment may reveal vomiting, hot flushed skin, and a decreased level of consciousness. The patient may also experience complications such as tachycardia, tachypnea, or hypotension. Other findings may include mottle cyanosis, if the patient has malignant hyperthermia; diarrhea if he is experiencing a thyroid storm; and signs of increased intracranial pressure when the problem is central nervous system trauma or hemorrhage. Heatstroke, brain stem compression, and thyroid storm are common causes of thermoregulatory dysfunction. Toxic doses of amphetamines and salicylates will also disrupt the thermoregulatory centers in the brain.

Other causes

Drugs

Hyperthermia can result from the use of tricyclic antidepressants and drugs that impair sweating, such as anticholinergics, phenothiazines, and monoamine oxidase inhibitors.

Impaired heat dissipation

Impaired heat dissipation occurs with severe dehydration, in which sweat production decreases heat loss by evaporation. It also occurs when the environmental temperature is high, and the body can’t rid itself of heat as fast as it’s being received.

Nursing considerations

Treat mild to moderate hyperthermia by providing a cool, restful environment. Replace oral or I.V. fluid and electrolyte losses. If the patient is experiencing heatstroke, apply cool water to the skin and fan the patient. Apply a hyperthermia blanket or ice packs to the groin and axilla. Expect treatment to continue until the patient’s body temperature drops to 102.2° F (39° C). Vital signs will require continuous monitoring, especially the core body temperature. Follow measures to avoid shivering. Employ additional external cooling measures, such as cool, wet sheets and tepid baths. Monitor hemodynamic parameters, fluid and electrolyte balance and laboratory and diagnostic studies. Monitor blood urea nitrogen and serum creatinine levels and assess for signs and symptoms associated with rhabdomyolysis.

ALERT: Don’t reduce the patient’s temperature too rapidly, as too rapid a reduction can lead to vasoconstriction, which can cause shivering.

Patient teaching

Caution the patient to reduce activity, especially outdoor activity, in the hot, humid weather. Advise him to wear light-colored, lightweight, loose-fitting clothing as well as a hat and sunglasses during hot weather. Instruct the patient to drink sufficient fluids, especially water, in hot weather and after vigorous physical activity. Warn him to avoid caffeine and alcohol in hot weather. Advise the patient to use air conditioning or to open windows and use a fan to help circulate air indoors.

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Book Source Details

• Book Title: Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series
• Author(s): Springhouse
• Year of Publication: 2007
• Copyright Details: Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series, Copyright © 2007 Lippincott Williams & Wilkins.

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More About This Book: Title: Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 1-58255-624-5

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