1. Cooling must be initiated immediately on the discovery of a hyperthermic state and must proceed rapidly. For a successful outcome, temperatures must be decreased to 39° C (102° F) or below within 1 hour of initiating treatment (Erickson & Prendergast, 2004).

2. Antipyretics are ineffective in lowering the body temperature and may result in additional complications, such as coagulopathy and hepatic damage (Erickson & Prendergast, 2004).

3. Initial diagnosis is often difficult. Early symptoms of significant heat illness are usually nonspecific (drowsiness, confusion, headache) and may be overlooked or attributed to other causes. The key to diagnosis is a history of a related incident (Schmidt & Nichols, 2005).

4. Do not sponge the patient with alcohol because it may be absorbed transcutaneously with resultant toxicity (Hadad Rav-Acha, Heled, Epstein, & Moran, 2004).

Ice packs

Ice water

Spray or misting bottle

Large circulating fans

Bathtub or wash basin

Cooling blanket

Peritoneal lavage equipment

Temperature probe for continuous monitoring (rectal, bladder, or esophageal)

Cooled intravenous fluids (place the bags in an ice water slurry for 15 to 20 minutes)

1. Place the patient on high-flow oxygen because oxygen demand is increased in the hyperthermic state (see Procedure 25). Using cool aerosol mist may moderate body temperature and minimize fluid loss due to rapid respiratory rate.

2. Initiate an intravenous line to restore intravascular volume (see Procedure 60).

3. Initiate additional resuscitative efforts as indicated.

4. Place the patient on a cardiac monitor because nonspecific ST-segment changes, conduction disturbances, and ventricular arrhythmias have been reported during cooling (see Procedure 55).

5. Draw blood for complete blood count, potassium, sodium, phosphorus, calcium, magnesium, prothrombin time and partial thromboplastin time, blood urea nitrogen, glucose, creatinine, liver function tests, and creatine phosphokinase determinations (see Procedure 58).

6. Remove all of the patient’s clothing.

7. Establish continuous temperature monitoring. Urinary bladder, rectal, or esophageal probes are options. Check the rectum for stool before placement of a rectal probe; if the probe is placed in feces, the reading is inaccurate.

8. Obtain a baseline 12-lead electrocardiogram (see Procedure 56).

9. Insert a urinary bladder catheter to monitor fluid output (see Procedure 104).

1. Evaporative cooling. Cover the patient with wet towels or spray the patient with water while circulating air around the patient with large fans to promote heat loss through evaporation. The latter method is preferred because of rapid heat loss, availability of supplies, and easy access to the patient.

2. Immersion in ice water is effective but logistically more difficult and adds the danger of injury or airway hazard because of the patient’s altered mental status in circumstances where rescue is hampered. Also, while the body heat is transferred to the cooler water, the coolness may induce peripheral vasoconstriction that shunts blood flow to the body core lowering the rate of transfer. Sponging the patient with ice water may be tried initially. If initial cooling efforts are not rapidly effective, ice water immersion may be undertaken.

3. Cover the patient with a cooling blanket (controversial and slow) (see Procedure 151).

4. Apply ice packs to the neck, axilla, and inguinal area. Place a dry interface between the skin and the cold pack. Monitor the underlying skin for cold injury. This method is less effective than immersion in ice water.

5. Administer dantrolene as prescribed for malignant hyperthermia or NMS. Dantrolene is not effective in environmental hyperthermia.

6. Internal methods of cooling may be necessary in the patient with severe hyperthermia or who does not respond to external methods. Internal methods include cold peritoneal lavage (see Procedure 95), cold gastric lavage (see Procedure 99), and cardiopulmonary bypass (Vicario, 2006).

7. Stop cooling at 39° C (102.2° F) because the body temperature continues to drift downward, and hypothermia may result if cooling measures are continued beyond this point.

1. Both the elderly and the very young are at risk for classic hyperthermia because of decreased thermoregulatory functioning. The elderly have a relative inability to adapt to environmental temperatures, a decreased ability to perspire, and other chronic medical conditions that affect their ability to acclimate to warmer temperatures. Dependent elderly persons are at increased risk due to inadequate fluid intake, poor ability to make their needs known, and medicines that inhibit thermoregulation. Institutionalized elderly persons at facilities with high staffing ratios or staff shortage are especially at risk. The very young have a shorter stature, placing them closer to radiated heat from asphalt or cement; have fewer sweat glands; and are more easily dehydrated.

2. Young adults (e.g., athletes, outdoor laborers, military personnel) are at risk for exertional hyperthermia. Education on prevention and early treatment should be provided to leaders of such groups. During periods of unusual heat stress weather, public service announcements should be made regarding prevention, early treatment, and EMS access.

3. Patients taking psychotropic medicines and anticholinergics are at risk for impaired thermoregulation.

1. Violent shivering with rapid cooling, which may result in further heat production. Shivering can be controlled by the use of benzodiazepines (Erickson & Prendergast, 2004).

2. Hypotension

3. Acute renal failure

4. Metabolic acidosis

5. Increased serum potassium

6. Frostbite caused by ice packs

7. Rhabdomyolysis in severe exertional hyperthermia

8. Disseminated intravascular coagulation

9. Hypothermia from overly vigorous cooling

10. Aspiration (gastric lavage)

• Awareness of environmental temperature and humidity

• The importance of staying in a cool environment

• Adequate fluid intake

• Avoiding extreme exertion during the hottest times of the day or in extreme weather

• Frequent rest breaks

• Proper conditioning

1. Hypothermia creates myocardial irritability, so patients must be handled gently and procedures performed cautiously because stimulation may precipitate ventricular fibrillation. The risk is highest at temperatures below 29° C (85.2° F) (AHA, 2005; Chang, 2005).

2. With active external rewarming, patients may experience rewarming shock, which is evidenced by a decrease in blood pressure resulting from vasodilation in previously vasoconstricted extremities.

3. With active external rewarming, patients may experience a temperature afterdrop, which results from the shunting of cold blood from extremities to the core, which further chills the myocardium and increases the potential for ventricular fibrillation. This phenomenon occurs infrequently and appears to be of little clinical significance (Ulrich & Rathlev, 2004).

4. Medications must be used judiciously because most drugs have little effect on the hypothermic patient and may cause complications on rewarming because of delayed metabolism of drugs (e.g., metabolic alkalosis with sodium bicarbonate, hypoglycemia with insulin).

5. Skin should not be massaged or rubbed, and alcohol should not be used on the skin of hypothermic patients; these techniques increase vasodilation and move cold blood from the extremities to the core.

6. Attempts at defibrillation are usually unsuccessful until core temperature is above 28° to 30° C (82° to 86° F) (Chang, 2005). The American Heart Association suggests that with severe hypothermia, defibrillation should be attempted once and then active internal rewarming should be instituted (AHA, 2005).

Cardiac monitor

Pulse oximeter

Warm intravenous (IV) solution (37.7° C [100° F])

IV fluid warmers

IV tubing

Warm normal saline for irrigation

Radiant warming lights

Heating pads

Hot water bottles

Forced air warming blanket

Cascade nebulizer or similar equipment to administer heated, humidified oxygen

Peritoneal lavage equipment

Urinary bladder catheter

Hemodialysis equipment

Cardiac bypass equipment

Gastric lavage equipment

Pleural lavage equipment

Hypothermia thermometer (capability to measure temperatures less than 34.4° C (94° F)

1. Remove the patient from the cold or wet environment. Remove all clothing, dry the patient, and place the patient on a stretcher covered with sheets or blankets to prevent heat loss via conduction. Long hair should be dried or positioned away from the patient’s head.

2. Initiate resuscitation as indicated for the patient in cardiac arrest. Endotracheal intubation is necessary unless the patient is alert and has intact protective airway reflexes. Preoxygenate the patient before intubation to avoid dysrhythmias. Factors precipitating dysrhythmias during intubation are rough technique, hypoxia, and acid-base abnormalities (Chang, 2005; Erickson & Prendergast, 2004).

3. Establish continuous temperature monitoring. Urinary bladder, rectal, or esophageal probes are options. Check the rectum for stool before placement of a rectal probe; if the probe is placed in feces, the reading is inaccurate.

4. Apply the cardiac monitor for ongoing assessment during the rewarming procedures (see Procedure 55).

5. Obtain a baseline 12-lead electrocardiogram (see Procedure 56).

6. Perform a bedside blood glucose test (see Procedure 59). Obtain blood for complete blood count, arterial blood gases (uncorrected for temperature) (see Procedure 19), potassium, glucose, calcium, magnesium, prothrombin time and partial thromboplastin time, fibrinogen, fibrin split products, amylase, lipase, blood urea nitrogen, and creatinine determinations (see Procedure 58).