Thermoregulation Concept
USING A HYPOTHERMIA BLANKET TO REGULATE BODY TEMPERATURE A hypothermia blanket, or cooling pad, is a blanket-sized aquathermia pad that conducts a cooled solution, usually distilled water, through coils in a plastic blanket or pad. It operates much like an aquathermia pad, except that the liquid is cooled instead of heated. Placing a patient on a hypothermia blanket or pad helps to lower body temperature. The nurse monitors the patient's body temperature and can reset the blanket setting accordingly. The blanket also can be preset to maintain a specific body temperature; the device continually monitors the patient's body temperature using a temperature probe (which is inserted rectally or in the esophagus, or placed on the skin) and adjusts the temperature of the circulating liquid accordingly. When applying a hypothermia blanket, follow these steps: -Perform hand hygiene and put on PPE, if indicated. -Review the medical order for the application of the hypothermia blanket. Obtain consent for the therapy per facility policy. -Check that the water in the electronic unit is at the appropriate level. -Check the temperature setting on the unit to ensure it is within the safe range. -Apply lanolin or a mixture of lanolin and cold cream to the patient's skin where it will be in contact with the blanket.
-Turn on the blanket and make sure the cooling light is on. Verify that the temperature limits are set within the desired safety range. -Place the hypothermia blanket on the bed and cover it with a sheet so that the patient's skin does not come in direct contact with the cold blanket. Position the blanket under the patient so that the top edge of the pad is aligned with the patient's neck. -Put on gloves. Lubricate the rectal probe and insert it into the patient's rectum unless contraindicated. Or tuck the skin probe deep into the patient's axilla and tape it in place. For patients who are comatose or anesthetized, use an esophageal probe. Remove gloves and perform hand hygiene. Attach the probe to the control panel for the blanket. -Wrap the patient's hands and feet in gauze if ordered, or if the patient desires. For male patients, elevate the scrotum off the hypothermia blanket with towels. -Recheck the thermometer and settings on the control panel. -Turn and position the patient regularly (every 30 minutes to 1 hour). Keep linens free from condensation. Reapply cream, as needed. Observe the patient's skin for change in color, changes in lips and nail beds, edema, pain, and sensory impairment. -Monitor vital signs and perform a neurologic assessment, per facility policy, usually every 15 minutes, until the body temperature is stable. In addition, monitor the patient's skin integrity, peripheral circulation, and fluid and electrolyte status, per facility policy. -Observe for signs of shivering, including verbalized sensations, facial muscle twitching or twitching of extremities, or hyperventilation. -Turn off the blanket according to facility policy, usually when the patient's body temperature reaches 1 degree above the desired temperature. Continue to monitor the patient's temperature until it stabilizes. -Remove PPE, if used. Perform hand hygiene.
Frostbite Frostbite is trauma from exposure to freezing temperatures and freezing of the intracellular fluid and fluids in the intercellular spaces. It results in cellular and vascular damage. Frostbite can result in venous stasis and thrombosis. Body parts most frequently affected by frostbite include the feet, hands, nose, and ears. Frostbite ranges from first degree (redness and erythema) to fourth degree (full-depth tissue destruction). Assessment and Diagnostic Findings A frozen extremity may be hard, cold, and insensitive to touch and may appear white or mottled blue-white. The extent of injury from exposure to cold is not always initially known. The patient history should include environmental temperature, duration of exposure, clothing worn, humidity, and the presence of wet conditions. Protective clothing may partially prevent exposure to cold environments; however, wearing wet socks and exercise/movement may diminish the protective effects of insulation by 45%. Management The goal of management is to restore normal body temperature. Constrictive clothing and jewelry that could impair circulation are removed. Wet clothing is removed as rapidly as possible. If the lower extremities are involved, the patient should not be allowed to ambulate. Controlled yet rapid rewarming is instituted. Frozen extremities are usually placed in a 37°C to 40°C (98.6°F to 104°F) circulating bath for 30- to 40-minute spans. This treatment is repeated until circulation is effectively restored. Early rewarming appears to decrease the amount of ultimate tissue loss. During rewarming, an analgesic for pain is given as prescribed, because the rewarming process may be very painful. To avoid further mechanical injury, the body part is not handled. Massage is contraindicated. Once rewarmed, the part is protected from further injury and is elevated to help control swelling. Sterile gauze or cotton is placed between affected fingers or toes to prevent maceration, and a bulky dressing is placed on the extremity. A foot cradle may be used to prevent contact with bedclothes if the feet are involved. Hemorrhagic blebs, which may develop 1 hour to a few days after rewarming, are left intact and not ruptured. Nonhemorrhagic blisters are débrided to decrease the inflammatory mediators found in the blister fluid.
A physical assessment is conducted with rewarming to observe for concomitant injury, such as soft tissue injury, dehydration, alcohol intoxication, or fat embolism. Problems such as hyperkalemia (e.g., from release of potassium in the damaged cells) and hypovolemia, which occur frequently in people with frostbite, are corrected. Risk of infection is also great; therefore, aseptic technique is used during dressing changes, and tetanus prophylaxis is given as indicated. Nonsteroidal anti-inflammatory drugs (NSAIDs) are prescribed for their anti-inflammatory effects and to control pain. Additional measures that may be carried out when appropriate after emergency stabilization measures have been instituted include the following: Whirlpool bath for the affected body parts to aid circulation and débridement of necrotic tissue to help prevent infection Escharotomy (incision through the eschar) to prevent further tissue damage, to allow for normal circulation, and to permit joint motion Fasciotomy to treat compartment syndrome After rewarming, hourly active motion of any affected digits is encouraged to promote maximal restoration of function and to prevent contractures. Discharge instructions also include encouraging the patient to avoid tobacco, alcohol, and caffeine because of their vasoconstrictive effects, which further reduce the already deficient blood supply to injured tissues.
ASSESSING A TEMPORAL ARTERY TEMPERATURE Measurement on the right or left side of the forehead is equally effective. When taking a temporal artery temperature, assess for head coverings. Anything covering the area—such as a hat, hair, wigs, or bandages—would insulate the area, resulting in falsely high readings. If a patient is lying on the side, measure only the side of the head exposed to the environment. Do not measure temporal artery temperature over scar tissue, open lesions, or abrasions. Move the thermometer across the forehead slowly and remain in contact with the skin to ensure accurate results. Temporal artery temperature readings are more accurate than axillary temperature measurement. Normal temporal artery temperature readings range from 37.1° to 38.1°C (98.7° to 100.5°F). ASSESSING AN AXILLARY TEMPERATURE The axillary site may be used when both oral and rectal sites are contraindicated or when these sites are inaccessible, but should not be used where accurate temperature measurement is required. The axilla remains the most common place for temperature measurement in the neonate. Axillary readings are affected by ambient temperature, local blood flow, placement of the probe, and closure of the axillary cavity. Place the probe in the center of the axilla; hold the patient's arm by the patient's side until the measurement is complete. Normal axillary temperature readings range from 35.9° to 36.9°C (96.7° to 98.5°F).
ASSESSING A RECTAL TEMPERATURE The rectal temperature, a core temperature, is considered to be one of the most accurate routes. However, many patients are embarrassed at having their temperature taken rectally. The rectal site should not be used in newborns, children with diarrhea, and in patients who have undergone rectal surgery or have a disease of the rectum. Because the insertion of the thermometer into the rectum can slow the heart rate by stimulating the vagus nerve, assessing a rectal temperature for patients with heart disease or after cardiac surgery may not be allowed in some institutions. In addition, assessing a rectal temperature is contraindicated in patients who are neutropenic (have low white blood cell counts, such as in leukemia) and in patients who have certain neurologic disorders (e.g., spinal cord injuries). Do not insert a rectal thermometer into a patient who has a low platelet count. The rectum is very vascular, and a thermometer could cause rectal bleeding. Normal rectal temperature readings range from 37.1° to 38.1°C (98.7° to 100.5°F).
ASSESSING AN ORAL TEMPERATURE When selecting the oral site, the patient must be able to close his or her mouth around the probe. Therefore, this site is not suitable for use with children less than 5 years old, for some children with developmental delay, with patients who are unable to follow directions, or for confused and comatose patients. If a patient has had either hot or cold food or fluids or has been smoking or chewing gum, the general recommendation is to wait 15 to 30 minutes to allow the oral tissues to return to normal temperature. Mouth breathing can influence the results. Oral temperatures should not be taken in people with diseases of the oral cavity, in those who have had surgery of the nose or mouth, or when there is a risk of seizures. In addition, oral temperatures should not be assessed in patients receiving oxygen by mask, because the time it takes to assess a reading is likely to result in a serious drop in the patient's blood oxygen level. Normal oral temperature readings range from 36.5° to 37.5°C (97.7° to 99.5°F). The probe must remain in the sublingual pocket for the full period of measurement.
ASSESSING A TYMPANIC MEMBRANE TEMPERATURE Infrared sensors in the thermometer sense heat from the body given off by the tympanic membrane. The thermometer does not touch the tympanic membrane. This site allows easy and safe measurement of temperature and is readily accessible. However, it should not be used for patients who have drainage from the ear, ear pain, ear infection, or scars on the tympanic membrane. Temperature readings are not significantly altered by the presence of cerumen (earwax) or otitis media (infection of the middle ear). Normal tympanic temperature readings range from 36.8° to 37.8°C (98.2° to 100°F)
19. A backcountry skier has been airlifted to the ED after becoming lost and developing hypothermia and frostbite. How should the nurse best manage the patients frostbite? A) Immerse affected extremities in water slightly above normal body temperature. B) Immerse the patients frostbitten extremities in the warmest water the patient can tolerate. C) Gently massage the patients frozen extremities in between water baths. D) Perform passive range-of-motion exercises of the affected extremities to promote circulation.
Ans: A Feedback: Frozen extremities are usually placed in a 37C to 40C (98.6F to 104F) circulating bath for 30- to 40minute spans. To avoid further mechanical injury, the body part is not handled. Massage is contraindicated.
27. The triage nurse is working in the ED. A homeless person is admitted during a blizzard with complaints of being unable to feel his feet and lower legs. Core temperature is noted at 33.2C (91.8F). The patient is intoxicated with alcohol at the time of admission and is visibly malnourished. What is the triage nurses priority in the care of this patient? A) Addressing the patients hypothermia B) Addressing the patients frostbite in his lower extremities C) Addressing the patients alcohol intoxication D) Addressing the patients malnutrition
Ans: A Feedback: The patient may also have frostbite, but hypothermia takes precedence in treatment because it is systemic rather than localized. The alcohol abuse and the alteration in nutrition do not take precedence over the treatment of hypothermia because both problems are a less acute threat to the patients survival.
A 6-year-old is admitted to the ED after being rescued from a pond after falling through the ice while ice skating. What action should the nurse perform while rewarming the patient? A) Assessing the patients oral temperature frequently B) Ensuring continuous ECG monitoring C) Massaging the patients skin surfaces to promote circulation D) Administering bronchodilators by nebulizer
Ans: B Feedback: A hypothermic patient requires continuous ECG monitoring and assessment of core temperatures with an esophageal probe, bladder, or rectal thermometer. Massage is not performed and bronchodilators would normally be insufficient to meet the patients respiratory needs.
28. A patient is brought to the ED by friends. The friends tell the nurse that the patient was using cocaine at a party. On arrival to the ED the patient is in visible distress with an axillary temperature of 40.1C (104.2F). What would be the priority nursing action for this patient? A) Monitor cardiovascular effects. B) Administer antipyretics. C) Ensure airway and ventilation. D) Prevent seizure activity.
Ans: C Feedback: Although all of the listed actions may be necessary for this patients care, the priority is to establish a patent airway and adequate ventilation.
20. A patient with a fractured femur presenting to the ED exhibits cool, moist skin, increased heart rate, and falling BP. The care team should consider the possibility of what complication of the patients injuries? A) Myocardial infarction B) Hypoglycemia C) Hemorrhage D) Peritonitis
Ans: C Feedback: The signs and symptoms the patient is experiencing suggest a volume deficit from an internal bleed. That the symptoms follow an acute injury suggests hemorrhage rather than myocardial infarction or hypoglycemia. Peritonitis would be an unlikely result of a femoral fracture.
26. A patient has been brought to the ED after suffering genitourinary trauma in an assault. Initial assessment reveals that the patients bladder is distended. What is the nurses most appropriate action? A) Withhold fluids from the patient. B) Perform intermittent urinary catheterization. C) Insert a narrow-gauge indwelling urinary catheter. D) Await orders following the urologists assessment.
Ans: D Feedback: Urethral catheter insertion when a possible urethral injury is present is contraindicated; a urology consultation and further evaluation of the urethra are required. The nurse would withhold fluids, but urologic assessment is the priority.
Heat-Induced Illnesses Heat-induced illnesses may range in severity from mild and self-limiting to life-threatening emergencies. The most serious of these—heat stroke—is an acute medical emergency caused by failure of the heat-regulating mechanisms of the body. It is the inability to maintain cardiac output in the face of moderately high body temperatures and is associated with dehydration. The most common cause of heat stroke is nonexertional, prolonged exposure to an environmental temperature of greater than 39.2°C (102.5°F), although a heat index of greater than 35°C (95°F) is associated with increased mortality. It usually occurs during extended heat waves, especially when they are accompanied by high humidity. Exertional heat stroke is caused by strenuous physical activity that occurs in a hot environment. People at risk for nonexertional heat stroke are those not acclimatized to heat, those who are older or very young, those unable to care for themselves, those with chronic and debilitating diseases, and those taking certain medications (e.g., major tranquilizers, anticholinergics, diuretics, beta blockers). In a study of heat-induced injury from 2006 to 2010, mortality was greater among older adults, men, and patients with pre-existing chronic illnesses. Heat-related events occurred most often in rural areas. Exertional heat stroke occurs in healthy individuals during sports or work activities (e.g., exercising in extreme heat and humidity). Hyperthermia results because of inadequate heat loss.
Chart 72-6 HEALTH PROMOTION Preventing Heat-Induced Illnesses The nurse provides the following advice for the patient treated for heat-induced illness: -Avoid immediate re-exposure to high temperatures; hypersensitivity to high temperatures may remain for a considerable time. -Maintain adequate fluid intake, wear loose clothing, and reduce activity in hot weather. -Monitor fluid losses and weight loss during workout activities or exercise and replace fluids and electrolytes. -Use a gradual approach to physical conditioning, allowing sufficient time for return to baseline temperature. -Plan outdoor activities to avoid the hottest part of the day (between 10 AM and 2 PM). For older patients living in urban settings with high environmental temperatures: -The nurse directs these patients to places where air conditioning is available (e.g., shopping mall, library, church) and advises them that fans alone are not adequate to prevent heat-induced illness. -Less severe forms of heat-induced illnesses include heat exhaustion and heat cramps or heat illness. The causes of heat exhaustion are the same as for heat stroke. Heat illness is caused by a loss of electrolytes, typically during strenuous physical activity in a hot environment. Gerontologic Considerations -Most heat-related deaths occur in older adults because their circulatory systems are unable to compensate for stress imposed by heat. Older adults have a decreased ability to perspire as well as a decreased ability to vasodilate and vasoconstrict. They have less subcutaneous tissue, a decreased thirst mechanism, and a diminished ability to concentrate urine to compensate for heat. Many older adults do not drink adequate amounts of fluid, partly because of fear of incontinence, and thus have a greater risk of heat stroke. In addition, many older adults fear being victims of crime, so even if their residence lacks air conditioning, they tend to keep windows closed despite high temperatures and humidity levels.
Select the option that best describes an observable physiological behavior exhibited by an individual attempting to conserve body heat. A. Oliguria B. Sweating C. Shivering D. Adducting the extremities
D. Adducting the extremities Shivering is a method of increasing heat production, not conservation.
The nurse observes the client's frequent use of the incentive spirometer. The client states "I do not want to have pneumonia while in the hospital." Which vital sign reading demonstrates effectiveness of this intervention? A. Respiratory rate of 12 breaths per minute B. Blood pressure of 126/84 mm Hg C. Pulse rate of 100 beats per minute D. Temperature of 98.2°F
D. Temperature of 98.2°F The client is trying to avoid pneumonia which is a febrile illness. The best indicator that this strategy is working is the absence of fever.
Decreased Body Temperature Hypothermia is a body temperature below the lower limit of normal. Hypothermia occurs when the compensatory physiologic responses meant to produce and retain heat are overwhelmed by unprotected exposure to cold environments. This may be a result of accidental exposure or impaired perception of cold, which occurs particularly in older adults or the disabled. Chronic conditions—such as alcoholism, malnutrition, and hypothyroidism—increase the risk of hypothermia. Patients in the perioperative period and newborn infants are also at increased risk. Death may occur when body temperature falls below 35°C (95°F), but survival has been reported in isolated cases (such as in drowning in very cold water or burial in snow) when body temperatures have fallen in the range of severe hypothermia (28°C [82.4°F]). Survival is possible because rates of chemical reactions in the body are slowed, thereby decreasing the metabolic demands for oxygen. Therapeutic hypothermia, the purposeful lowering of the core body temperature, has been used to improve outcomes after cardiac arrest. This decreased body temperature reduces metabolic rate and oxygen demand of the body to improve survival and neurologic outcomes Physical Effects of Hypothermia Patients with hypothermia may experience poor coordination, slurred speech, poor judgment, amnesia, hallucinations, and stupor. Respirations decrease and the pulse becomes weak and irregular with lowering blood pressure. Treatment of Hypothermia Treatment of hypothermia includes rewarming the patient. Rewarming can be accomplished by covering with additional clothing and blankets, the use of heating blankets and pads, and radiant warmers. Warm fluids are administered either orally or through the intravenous route.
Equivalent Celsius and Fahrenheit Temperatures: To convert Celsius to Fahrenheit, multiply by 9/5 and add 32. To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9. CELSIUS to FAHRENHEIT 35.0 95.0 36.0 96.8 36.5 97.6 37.0 98.6 37.5 99.5 38.0 100.4 38.5 101.3 39.0 102.2 40.0 104.0 41.0 105.8
Typically, a preterm newborn that is having problems with thermal regulation is cool to cold to the touch. The hands, feet, and tongue may appear cyanotic. Respirations are shallow or slow, or signs of respiratory distress are present. The newborn is lethargic and hypotonic, feeds poorly, and has a feeble cry. Blood glucose levels are probably low, leading to hypoglycemia, due to the energy expended to keep warm. When promoting thermal regulation for the preterm newborn: Remember the four mechanisms for heat transfer and ways to prevent loss: Convection: heat loss through air currents (avoid drafts near the newborn) Conduction: heat loss through direct contact (warm everything the newborn comes in contact with, such as blankets, mattress, stethoscope) Radiation: heat loss without direct contact (keep isolettes away from cold sources and provide insulation to prevent heat transfer) Evaporation: heat loss by conversion of liquid into vapor (keep the newborn dry and delay the first bath until the baby's temperature is stable)
Frequently assess the temperature of the isolette or radiant warmer, adjusting the temperature as necessary to prevent hypo- or hyperthermia. Utilize plastic wraps and bags, skin-to-skin contact, or transwarmer mattresses if available to keep infants warmer and decrease the incidence of hypothermia. Assess the newborn's temperature every hour until stable. Observe for clinical signs of cold stress, such as respiratory distress, central cyanosis, hypoglycemia, lethargy, weak cry, abdominal distention, apnea, bradycardia, and acidosis. --Remember the complications of hypothermia and frequently assess the newborn for signs: --Metabolic acidosis secondary to anaerobic metabolism used for heat production, which results in the production of lactic acid --Hypoglycemia due to depleted glycogen stores --Pulmonary hypertension secondary to pulmonary vasoconstriction --Monitor the newborn for signs of hyperthermia such as tachycardia, tachypnea, apnea, warm to touch, flushed skin, lethargy, weak or absent cry, and CNS depression; adjust the environmental temperature appropriately. --Explain to the parents the need to maintain the newborn's temperature, including the measures used; demonstrate ways to safeguard warmth and prevent heat loss
heat stroke symptoms
Heat stroke Can be fatal!> 40 Celsius / > 104 Fahrenheit anhidrosis (absence of sweating) hypotension seizures syncope irritability confusion coordination issues flushed skin / hot & dry tachypnea tachycardia coma
What is hypothermia? < 35 Celsius / < 95 Fahrenheit Heat produced < Heat loss Life threatening emergency Intervention Strategies for Hypothermia Remove the person from cold Provide external warming measures Provide internal warming measures Safety Tip: Core rewarming must be done slowly to minimize the risk for dysrythmias. Cardiac monitoring is required when the patient is recovering from severe hypothermia.
Induced most frequent reason: --Reduce metabolic rates & lower cellular demand for oxygen in tissues - particularly brain --used to reduce neurological damage following head trauma, strokes, or during cardiac surgery used post cardiac arrest (less anoxia if hypothermia induced) -------initiated with iced saline gastric lavage, ice packs in axilla and groin - cooling blanket at 5 Celsius --Goal client temperature of 33 Celsius / After 24 hours, temperature is gradually increased by 1 degree every 2-4 hours/ --Stop all potassium administration during rewarming, damaged cells will release potassium, serum potassium levels will rise --Clients sedated, paralytic medications administered, prevents shivering, produces heat, reduces effectiveness of induced hypothermia Accidental Exposure to cold environment Immersion in cold water Lack of adequate clothing, shelter, heat Associated with near-drowning, body heat lost more quickly in water than air Other causes: ingestion of alcohol, barbiturates, trauma, brain disorder(interferes with temperature regulation), overwhelming sepsis Routes of heat loss Internal core to body surface External surface to environment Core temp --usually higher than skin temperature/results in continuous transfer or conduction of heat to surface --transfer accomplished through increase in O2 consumption, depletion of glycogen stores, metabolism of brown fat (in infants)
Types of fevers
Intermittent: The body temperature returns to normal at least once every 24 hours. Remittent: The body temperature does not return to normal and fluctuates a few degrees up or down. Sustained or Continuous: The body temperature remains above normal with minimal variations. Relapsing or Recurrent: The body temperature returns to normal for one or more days with one or more episodes of fever, each as long as several days. fever spike: elevated temp but not real fever
Intervention Strategies for Hyperthermia Remove excess clothing and blankets Provide external cool packs Provide a cooling blanket Hydrate with cool fluids (oral or intravenous) Lavage with cool fluids Administer antipyretic drug therapy
Malignant Hyperthermia may occur in any patient, including patients who have previously had uneventful general anaesthesia. Treating the consequences of Malignant Hyperthermia: Stop the TRIGGER • Declare an emergency and where possible stop the surgery GIVE DANTROLENE AS A PRIORITY / IMMEDIATE MANAGEMENT WITH DANTROLENE IS ESSENTIAL • Treat the hyperkalemia • Cool the patient if T > 38.5°C • Treat the acidosis • Treat arrhythmias (if resistant consider hyperkalemia as cause)
Assessment and Diagnostic Findings Heat stroke, whether the cause is exertional or nonexertional, causes thermal injury at the cellular level, resulting in coagulopathies and widespread damage to the heart, liver, and kidneys. Recent patient history reveals exposure to elevated ambient temperature or excessive exercise during extreme heat. When assessing the patient, the nurse notes the following symptoms: profound central nervous system (CNS) dysfunction (manifested by confusion, delirium, bizarre behavior, coma, seizures); elevated body temperature (40.6°C [105°F] or higher); hot, dry skin; and usually anhidrosis (absence of sweating), tachypnea, hypotension, and tachycardia. The patient with heat exhaustion, on the other hand, may exhibit similarly high body temperatures accompanied by headaches, anxiety, syncope, profuse diaphoresis, gooseflesh, and orthostasis. The cardinal manifestations of heat cramps include muscle cramps, particularly in the shoulders, abdomen, and lower extremities; profound diaphoresis; and profound thirst.
Management The main goal is to reduce the high body temperature as quickly as possible, because mortality in heat stroke or morbid progression to heat stroke with less serious forms of heat-induced illnesses is directly related to the duration of hyperthermia. For the patient with heat stroke, simultaneous treatment focuses on stabilizing oxygenation using the CABs (circulation, airway, and breathing) (formerly referred to as the ABCs) of basic life support. This includes establishing IV access for fluid administration. After the patient's clothing is removed, the core (internal) temperature is reduced to 39°C (102°F) as rapidly as possible, preferably within 1 hour. One or more of the following methods may be used as prescribed: -Cool sheets and towels or continuous sponging with cool water -Ice applied to the neck, groin, chest, and axillae while spraying with tepid water -Cooling blankets -Immersion of the patient in a cold water bath is the optimal method for cooling (if available) -During cooling procedures, an electric fan is positioned so that it blows on the patient to augment heat dissipation by convection and evaporation. The patient's temperature is constantly monitored with a thermistor placed in the rectum, bladder, or esophagus to evaluate core temperature. Caution is used to avoid hypothermia and to prevent hyperthermia, which may recur spontaneously within 3 to 4 hours. The cooling process should stop at 38°C (100.4°F) in order to avoid iatrogenic hypothermia.
Hypothermia Hypothermia is a condition in which the core (internal) temperature is 35°C (95°F) or less as a result of exposure to cold or an inability to maintain body temperature in the absence of low ambient temperatures. Urban hypothermia (extreme exposure to cold in an urban setting) is associated with a high mortality rate; older adults, infants, people with concurrent illnesses, and those who are homeless are particularly susceptible. Alcohol ingestion increases susceptibility because it causes systemic vasodilation. Some medications (e.g., phenothiazines) or medical conditions (e.g., hypothyroidism, spinal cord injury) decrease the ability to shiver, hampering the body's innate ability to generate body heat. Fatigue and sleep deprivation are also associated with the development of hypothermia. Heat loss of 2% is normal but increases with exposure. Wet clothing accelerates heat loss, and immersion in cold water increases heat loss by 25%. Victims of trauma are also at risk for hypothermia resulting from treatment with cold fluids, unwarmed oxygen, and exposure during examination. The patient may also have frostbite, but hypothermia takes precedence in treatment. Assessment and Diagnostic Findings Hypothermia leads to physiologic changes in all organ systems. There is progressive deterioration, with apathy, poor judgment, ataxia, dysarthria, drowsiness, pulmonary edema, acid-base abnormalities, coagulopathy, and eventual coma. Shivering may be suppressed at a temperature of less than 32.2°C (90°F), because the body's self-warming mechanisms become ineffective. The heartbeat and blood pressure may be so weak that peripheral pulses become undetectable. Cardiac dysrhythmias may also occur. Other physiologic abnormalities include hypoxemia and acidosis. Management Management consists of removal of wet clothing, continuous monitoring, rewarming, and supportive care.
Monitoring The CABs of basic life support are a priority. The patient's vital signs, CVP, urine output, arterial blood gas levels, blood chemistry determinations (blood urea nitrogen, creatinine, glucose, electrolytes), and chest x-rays are evaluated frequently. Core body temperature is monitored with an esophageal, bladder, or rectal thermistor. Continuous ECG monitoring is performed, because cold-induced myocardial irritability leads to conduction disturbances, especially ventricular fibrillation. An arterial line is inserted and maintained to record blood pressure and to facilitate blood sampling. Rewarming Rewarming methods include active internal (core) rewarming and passive (spontaneous) or active external rewarming. Active internal (core) rewarming methods are used for moderate to severe hypothermia (less than 28°C to 32.2°C [82.5°F to 90°F]) and include cardiopulmonary bypass, warm fluid administration, warmed humidified oxygen by ventilator, and warmed peritoneal lavage. Monitoring for ventricular fibrillation as the patient's temperature increases from 31°C to 32°C (88°F to 90°F) is essential. Passive or active external rewarming is used for mild hypothermia (32.2°C to 35°C [90°F to 95°F]). Passive external rewarming uses over-the-bed heaters to the extremities and increases blood flow to the acidotic, anaerobic extremities. The cold blood from peripheral tissues has high lactic acid levels. As this blood returns to the core, it causes a significant drop in the core temperature (i.e., core temperature afterdrop) and can potentially cause cardiac dysrhythmias and electrolyte disturbances. Active external rewarming uses forced-air warming blankets. Care must be taken to prevent extremity burn from these devices, because the patient may not have effective sensation to feel the burn. Supportive Care Supportive care during rewarming includes the following as directed: External cardiac compression (typically performed only as directed in patients with temperatures higher than 31°C [88°F]) Defibrillation of ventricular fibrillation. A patient whose temperature is less than 32°C [90°F] experiences spontaneous ventricular fibrillation if moved or touched. Defibrillation is ineffective in patients with temperatures lower than 31°C (88°F); therefore, the patient must be rewarmed first. Mechanical ventilation with positive end-expiratory pressure (PEEP) and heated humidified oxygen to maintain tissue oxygenation Administration of warmed IV fluids to correct hypotension and to maintain urine output and core rewarming, as described previously Administration of sodium bicarbonate to correct metabolic acidosis if necessary Administration of antiarrhythmic medications Insertion of an indwelling urinary catheter to monitor urinary output and kidney function
Other types of increased body temperature are hyperthermia, neurogenic fever, and fever of unknown origin (FUO). Hyperthermia differs from fever in that the hypothalamic set point is not changed, but in situations of extreme heat exposure or excessive heat production (e.g., during strenuous exercise), the mechanisms that control body temperature are ineffective. Neurogenic fever is the result of damage to the hypothalamus from pathologies such as intracranial trauma, intracranial bleeding, or increased intracranial pressure. This type of fever does not respond to antipyretic medications. A fever of 38.3°C (101°F) or higher that lasts for 3 weeks or longer without an identified cause is diagnosed as an FUO.
Phases of Febrile Episodes of Fever: --Chill Phase Chills, Shivers, Feels cold(time period when temp is rising to meet new set point) --Plateau (Fever) Phase Chills subside, Feels warm and dry(Occurs when new set point is reached, higher temp) --Crisis Phase Warm, flushed, diaphoresis (dehydration)(Occurs if new set point is overshot or pyrogens are removed hypothalamus set point drops) --Flush Phase Cooling mechanisms to decrease temp
Nursing interventions to help maintain body temperature include: (NEWBORN) Dry the newborn immediately after birth to prevent heat loss through evaporation. Wrap the baby in warmed blankets to reduce heat loss via convection. Skin-to-skin contact with mother as soon as stabilized. Use a warmed cover on the scale to weigh the unclothed newborn. Warm stethoscopes and hands before examining the baby or providing care. Avoid placing newborns in drafts or near air vents to prevent heat loss through convection. Delay the initial bath until the baby's temperature has stabilized to prevent heat loss through evaporation. Avoid placing cribs near cold outer walls to prevent heat loss through radiation. Put a cap on the newborn's head after it is thoroughly dried after birth. Place the newborn under a temperature-controlled radiant warmer
Typically newborns use nonshivering thermogenesis for heat production by metabolizing their own brown adipose tissue. However, the preterm newborn has an inadequate supply of brown fat because he or she left the uterus early before the supply was adequate. The preterm newborn also has decreased muscle tone and thus cannot assume the flexed fetal position, which reduces the amount of skin exposed to a cooler environment. In addition, preterm newborns have large body surface areas compared to their weight. This allows an increased transfer of heat from their bodies to the environment.
hyperpyrexia
extremely high body temperature or fever ( 41.5*c)
Hyperthermia
high body temperature ( 37.6*c)
Increased temp vs decreased temp (connects back to hypothalamus)
increased temp: blood vessels dilate, giving flushed appearance, sweat glands become more active. decreased temp: blood vessels constrict, heat is trapped in deeper tissues, sweat glands become less active and skeletal muscles contract causing shivering.
Conduction heat loss
is the loss of heat from the BODY SURFACE to COOLER SURFACES in direct contact. Example The body transfers heat to an ice pack, causing the ice to melt.
Radiation heat loss
is the loss of heat from the body surface to COOLER SOLID SURFACES NOT in direct contact but in relative proximity Example The body gives off waves of heat from uncovered surfaces.
Hypothermia
low body temperature (36.2*c)
Normothermia
normal body temperature (36.5 to 37.5 *c) 97.7 - 99.5 F
Convection heat loss
the flow of heat from the body surface to COOLER AIR. Example An oscillating fan blows currents of cool air across the surface of a warm body.
Evaporation heat loss
the loss of heat that occurs when a liquid is converted to a vapor. Example Body fluid in the form of perspiration and insensible loss is vaporized from the skin.
