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heat and moisture exchanger

A device that retains some warmth and moisture from expired air and returns it to the intubated or laryngectomized patient during the following inspiration. The device prevents the patient from inhaling excessively cool, dry air that may damage the lower airways.

heat gun

A device used in splint fabrication that produces heated air to render thermoplastic splinting materials malleable for fitting.


(hēt′lā′bīl″, hēt′lā′bĭl) Easily changed or destroyed by heat; unstable. SYN: thermolabile. SEE: heat-stable.


Not easily changed or destroyed by heat; stable. A heat-stable substance may remain active at temperatures as high as 212°F (100°C). SEE: heat-labile.


(hēt′strōk″) The most severe of the heat-related illnesses, characterized by high fevers (over 104°F [40°C]), neurological impairment, and, frequently, death. SYN: sunstroke. SEE: Nursing Diagnoses Appendix.

 INCIDENCE: In the U.S., an average of 650 people die of heat-related illnesses each year. The incidence increases in the summer.

 CAUSES: Heatstroke is a failure of the body’s heat-regulating mechanisms during or after exposure to heat and high relative humidity (normally air temperatures of higher than 79°F (26.1°C) and relative humidity greater than 70%). In young healthy people it most often follows strenuous physical activity; in inactive individuals or older adults, it is commonly related to cardiovascular disease or use of drugs that influence body temperature regulation.

 SYMPTOMS AND SIGNS: Heatstroke is marked by high body temperature (over 104°F [40°C]); headache; numbness and tingling; confusion preceding sudden onset of seizures, delirium, or coma; tachycardia; rapid respiratory rate; and increased blood pressure followed by hypotension. Multiple organ system failure is common. On presentation to the hospital, patients with non-activity-related heatstroke may have hot, dry, red skin; the skin of active people may still be damp from perspiration, but sweating will cease as the condition worsens.

 DIAGNOSIS: There are no specific diagnostic tests for heatstroke, and its diagnosis is clinically established. Diseases that mimic heatstroke (sepsis, neuroleptic malignant syndrome, febrile drug reactions) should be sought and excluded. Patients who die of heatstroke often have very elevated serum lactate, troponin, and creatinine levels, abnormalities of liver function and coagulation, advanced age, general debility, or multiple existing medical conditions.

 PREVENTION: Heat-related illnesses (heat cramps, heat exhaustion, heatstroke) are preventable through education of the public. Athletes, soldiers, and laborers are taught to recognize the signs and symptoms of heat problems and the importance of prevention, e.g., by avoiding prolonged exposure to heat, and by increasing their electrolyte and water intake, and prompt treatment of symptoms. High-risk patients (older adults, obese, diabetic, or alcoholic, those with cardiac disease and other chronic debilitating illnesses, and those taking phenothiazines or ...

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