NSG 170 Test Two (Thermoregulation)

The hypothalamus establishes a:

"Set point"—meaning the temperature level for optimal physiological functioning The hypothalamic set point for core body temperature is 37°C (98.6°F)

Reported symptoms (of hyperthermia) may include:

- "Feeling feverish" or "feeling hot" - Chills - General malaise - Lethargy - Weakness - Dizziness - Loss of appetite - Muscle cramps

Electronic thermometers provide two modes of operation:

- A 4-second predictive temperature - A 3-minute standard temperature

The electronic thermometer consists of:

- A rechargeable battery-powered display unit - A thin wire cord - A temperature-processing probe covered by a disposable probe cover

Serum calcium and potassium levels are increased, as is the metabolic rate, leading to:

- Acidosis - Cardiac dysrhythmias - High body temperature

Core rewarming methods for moderate hypothermia include:

- Administration of warm IV fluids - Heated oxygen or inspired gas to prevent further heat loss via the respiratory tract - Heated peritoneal, pleural, gastric, or bladder lavage

Risk factors that affect thermoregulation include:

- Age - Environment - Physiological condition of individual

The condition is characterized by:

- Alterations in mental status - An increase in body temperature, with hot dry skin Severe conditions can be fatal

Third-Degree Frostbite

- Appears as small blisters that contain dark fluid and an affected body part that is cool, numb, blue, or red and does not blanch - Full-thickness and subcutaneous tissue necrosis occurs and requires debridement

The greatest amount of heat is produced:

- By muscles - Through metabolic activity in the liver

Sustained high core body temperature coupled with reduced perfusion leads to:

- Cerebral edema - Central nervous system degeneration - Renal necrosis

Fluctuation outside this range is an indication of a:

- Disease process - Strenuous or unusual activity - Extreme environmental exposure

AORN recommends that all ORs have a dedicated MH cart containing:

- Drugs for management (normal saline, dantrolene, sodium bicarbonate, insulin, 50% dextrose, lidocaine, calcium chloride) - A protocol card listing interventions - MH hotline number

Passive measures include:

- Dry and warm clothing - Warm drinks - Exercise

Patients will often present with:

- Dry skin and mucous membranes - Decreased urinary output - And other signs of dehydration and electrolyte imbalance

This can occur as a result of several factors, including:

- Environment (temperature, humidity, and lack of air movement) - Excessive physical exertion (particularly in hot, humid environments without sufficient water replacement) - Genetic abnormality - Metabolic diseases - Injury to the hypothalamus - As a result of pharmacologic agents

Primary prevention measures include:

- Environmental control and shelter - Appropriate clothing for different conditions - Physical activity

Accidental hypothermia results from:

- Environmental exposure (including staying out in the cold too long, wearing insufficient clothing for weather conditions, wet clothing, and cold water submersion) - Or as a complication from serious systemic disorders

What are some contributing factors?

- Fatigue - Dehydration - Poor nutrition

Monitor for early signs of complications that can occur after rewarming such as:

- Fluid, electrolyte, and metabolic abnormalities - Acute respiratory distress syndrome (ARDS) - Acute renal failure - Pneumonia

The patient with a genetic predisposition for MH is at risk when exposed to:

- Halothane - Enflurane - Isoflurane - Desflurane - Sevoflurane - Succinylcholine

Active methods incorporate:

- Heating blankets - Warm packs - Convective air heaters or warmers to speed rewarming

Over time, excessive body temperature can lead to:

- Hypotension - Tachycardia - Decreased cardiac output, progressing to reduced perfusion and coagulation within the microcirculation and cardiovascular collapse

MH may start:

- Immediately after anesthesia induction - Several hours into the procedure - Or even after anesthesia is completed

Epinephrine increases heat production by:

- Increasing the metabolic rate - Stimulating glycolysis - Causing vasoconstriction

Active core rewarming strategies include:

- Infusion of warm intravenous solutions - Gastric lavage with warm fluid - Peritoneal lavage with warm fluid - Inhalation of warmed oxygen

The skin regulates temperature through:

- Insulation of the body - Vasoconstriction (which affects the amount of blood flow and heat loss to the skin) - Temperature sensation

First-Degree Frostbite

- Least severe type of frostbite - Involves hyperemia (increased blood flow) of the involved area and edema formation

Hypothermia is commonly divided into three categories by severity

- Mild (90° to 95° F [32° to 35° C]) - Moderate (82.4° to 90° F [28° to 32° C]) - Severe (below 82.4° F [28° C])

Fourth-Degree Frostbite

- Most severe form - There are no blisters or edema - The part is numb, cold, and bloodless - The full-thickness necrosis extends into the muscle and bone - At this stage, gangrene develops, which may require amputation of the affected part

For treatment of mild hypothermia, the person needs to be:

- Needs to be sheltered from the cold environment - Have all wet clothing removed - Undergo passive or active external rewarming

However, active rewarming measures may be necessary and include:

- Providing warm blankets or heating pads - Drawing a warm water bath - Placing the patient in a heated environment

Heat production occurs during:

- Rest - Voluntary movements - Involuntary shivering - Nonshivering thermogenesis

What keeps heat inside of the body?

- Skin - Subcutaneous tissue - Fat People with more body fat have more natural insulation than do slim and muscular people

Like burns, frostbite injuries can be:

- Superficial - Partial - Full thickness

Mechanisms of heat loss include:

- Sweating - Vasodilation (widening) of blood vessels, and inhibition of heat production

Symptoms, caused by increased muscle calcium and increased metabolism, include:

- Tachycardia - Dysrhythmias - Muscle rigidity of the jaw and upper chest - Hypotension - Tachypnea - Skin mottling - Cyanosis - Myoglobinuria (muscle proteins in the urine)

External continuous cooling methods include:

- Using cooling blankets - Applying ice packs in the axillae and groin and on the neck and head

What should you teach patients to keep in their car when driving in winter in case vehicle becomes stranded?

- Water - Extra clothing - Blankets - Food

In the Celsius version there are 50 dots, each representing a temperature increment of:

0.1° C, over a range of 35.5° C to 40.4° C The Fahrenheit version has 45 dots with increments of 0.2° F and a range of 96° F to 104.8° F

Body temperature normally changes:

0.5° to 1° C (0.9° to 1.8° F) during a 24-hour period However, temperature is one of the most stable rhythms in humans

Epidemiologic studies reveal that malignant hyperthermia complicates:

1 in approximately 100,000 surgeries in adults 1 in approximately 30,000 surgical procedures in children

Temperature patterns are not automatically reversed in people who work at night and sleep during the day. How long does it take for the cycle to reverse?

1-3 weeks

Three physiological factors can lead to hypothermia:

1. Excessive heat loss 2. Insufficient production of heat 3. Dysfunction of hypothalamic regulatory mechanisms

The three physiological mechanisms that coordinate body temperature are also the three mechanisms that can lead to hyperthermia:

1. Excessive heat production 2. Inadequate ability to cool 3. Hypothalamic regulator dysfunction

The ability of a person to control body temperature depends on:

1. The degree of temperature extreme 2. The person's ability to sense feeling comfortable or uncomfortable 3. Thought processes or emotions 4. The person's mobility or ability to remove or add clothes Individuals are unable to control body temperature if any of these abilities is lost

The two variables that affect the extent of consequences for hypothermia and hypothermia are:

1. The extent of temperature change 2. The duration of temperature variation

When it is necessary to convert temperature readings, use the following formulas:

1. To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit reading and multiply the result by 5/9 2. To convert Celsius to Fahrenheit, multiply the Celsius reading by 9/5 and add 32 to the product

For each hour of exercise in hot conditions, how much body fluid can be lost in sweat?

1/2 - 2 L

Continue aggressive interventions to cool patient until rectal temperature is:

102° F (38.9° C)

The temperature is usually lowest between:

1:00 and 4:00 AM

The CDC reported that non-Hispanic Blacks had a heat-related mortality rate:

2.5 times that of non-Hispanic Whites Likewise, non-Hispanic Blacks had a cold-related mortality rate 2.0 times that of non-Hispanic Whites

When protected from environmental extremes, the newborn's body temperature is usually within:

35.5° to 37.5° C (95.9° to 99.5° F)

In the elderly population the average core temperature ranges from:

35° to 36.1° C (95° to 97° F) as a result of decreased immunity

Normal body temperature ranges from:

36.2° to 37.6°C (97.0°-100°F) An average of 37°C (98.6°F)

It is recommended that a newborn's axillary temperature be regulated at:

36.5°C or 97.8°F

Body tissues and cells function efficiently within a narrow range, from:

36° to 38° C (96.8° to 100.4° F) But no single temperature is normal for all people

For healthy young adults the average oral temperature is:

37° C (98.6° F)

Fever is an important defense mechanism. Mild temperature elevations as high as:

39° C (102.2° F) enhance the immune system of the body

A fever is usually not harmful if it stays below:

39° C (102.2° F) in adults Or below 40° C (104° F) in children

In extreme heat, an individual can lose as much as:

4 L of fluids in an hour For this reason, replacement of fluids and electrolytes is essential to prevent dehydration

During these periods often intermittent skin temperature increases up to:

4° C (7.2° F), referred to as hot flashes This is caused by the instability of the vasomotor controls for vasodilation and vasoconstriction

Perspiration provides a significant source of heat reduction and normally accounts for how much water loss per day?

600 mL

Hyperthermia

A body temperature above normal range (>37.6°C)

Hypothermia

A body temperature below normal range (<36.2°C)

Without proper clothing or shelter, environmental exposure presents:

A challenge to thermoregulatory systems of the body

Patterns of Fever - Sustained

A constant body temperature continuously above 38° C (100.4° F) that has little fluctuation

Hypothermia is:

A core body temperature below 95° F (35° C)

Frostbite destroys tissue and produces:

A deep tetanus-prone wound The patient should be immunized to prevent tetanus

Fevers and fever patterns serve:

A diagnostic purpose

Fever of Unknown Origin (FUO)

A fever with an undetermined cause

Heat loss can be increased through peripheral vasodilation, which brings:

A greater volume of blood to the body surface

People who smoke, consume alcohol, or have impaired peripheral circulation have:

A higher incidence of frostbite

A patient who is anxious about entering a hospital or a health care provider's office often has:

A higher normal temperature

Extremely elevated temperature, as high as 111.2° F (44° C), is:

A late sign of MH

When temperatures become extremely hot or cold, health-promoting behaviors such as removing or adding clothing have:

A limited effect on controlling temperature

During the day body temperature rises steadily to:

A maximum temperature value at about 4:00 PM and then declines to early-morning levels

Optimal physiological function of the human body occurs when:

A near-constant core temperature is maintained.

If shivering occurs during the cooling process, give:

A parenteral benzodiazepine such as diazepam (Valium) Lorazepam (Ativan) is an alternative agent

If a patient has a cardiac or respiratory problem, the stress of a fever is great. A prolonged fever weakens:

A patient by exhausting energy stores

The site of temperature measurement (oral, rectal, tympanic membrane, temporal artery, esophageal, pulmonary artery, axillary, or even urinary bladder) is one factor that determines:

A patient's temperature

A subnormal temperature requires:

A radiant warmer for additional heat

However, when an individual has hyperthermia or hypothermia, the most reliable means available for assessing core temperature is:

A rectal temperature A lubricated probe is inserted into the rectal canal at a depth of 1-1.5 in. in the adult and 0.5-1 in. in the child

Nursing assessment for alterations in thermoregulation begins with:

A set of vital signs

The presence of fever is considered an expected finding with:

A systemic inflammatory response

Another disposable thermometer useful for screening temperature is:

A temperature-sensitive patch or tape Applied to the forehead or abdomen, chemical sensitive areas of the patch change color at different temperatures This type of thermometer can also be affected by environmental temperatures

Conduction

A transfer of heat through direct contact of one surface to another Warmer surfaces lose heat to cooler surfaces

Hypothermia may be either:

Accidental or therapeutic

When core body temperature falls below 30°C, what is indicated?

Active core rewarming measures Meaning there is an application of heat directly to the core

Voluntary movements such as muscular activity during exercise require:

Additional energy

By regulating perspiration or sweating, the body promotes:

Additional evaporative heat loss

As metabolism increases, what is produced?

Additional heat

Increased metabolism requires:

Additional oxygen

Swaddling, a cap for the head, and/or skin-to-skin contact are:

Additional ways to keep the infant warm

People of low socioeconomic status may lack resources for:

Adequate clothing, heating, and cooling

Hyperthermia results because the body cannot:

Adequately cool itself and keep the temperature at the correct level

What interventions should you perform for a patient in the rewarming process?

Administer analgesics, especially IV opiates, and IV rehydration Ibuprofen 400 mg to 800 mg PO should also be administered every 8 hours as it decreases thromboxane production in the inflammatory cascade and may reduce secondary tissue injury in frostbite

When the fever "breaks," the patient becomes:

Afebrile

Nursing Safety Priority - Critical Rescue

After ensuring that patient has patent airway, effective breathing, and adequate circulation, recognize that you must use rapid cooling as first priority for care Respond by implementing methods for rapid cooling, which include: - Removing clothing - Placing ice packs on neck, axillae, chest and groin - Immersing patient or wetting patient's body with cold water - Fanning rapidly to aid in evaporative cooling

According to the Centers for Disease Control and Prevention (CDC), heat- and cold-related deaths drastically rise among adults older than:

Age 75

Patients with more severe and deeper forms of frostbite need:

Aggressive treatment

The degree of heat loss through radiation is directly related to the difference between:

Ambient air temperature, skin temperature, and exposure

A true fever results from:

An alteration in the hypothalamic set point

Susceptibility to MH is inherited as:

An autosomal dominant disorder Several forms of genetic mutations increase susceptibility

Fever can also occur due to:

An exaggerated immune response such as autoimmune disorders or allergic reaction

Hyperpyrexia

An extremely high body temperature

Illnesses, a decreased level of consciousness, or impaired thought processes result in:

An inability to recognize the need to change behavior for temperature control

When heat-related conditions occur, the body's natural ability to dissipate heat is interrupted, resulting in:

An increase in body temperature that exceeds heat loss

The most sensitive indication is:

An unexpected rise in the end-tidal carbon dioxide level with a decrease in oxygen saturation and tachycardia

Myocardial hypoxia produces:

Angina (chest pain)

Pyrogens act as:

Antigens, triggering immune system responses

Symptomatic relief of persistent or intermittent fevers can be treated with:

Antipyretics such as nonsteroidal anti-inflammatory drugs (e.g., naproxen or ibuprofen and aspirin) and acetaminophen

What should you apply to the damaged areas?

Apply only loose, nonadherent sterile dressings Avoid compression of the injured tissues Both topical and systemic antibiotics may be used

Passive methods involve:

Applying warm clothing or blankets

However, the average body temperature of older adults is:

Approximately 35° to 36.1° C (95° to 97° F)

Endogenous Pyrogens

Are produced by phagocytic white blood cells as part of the immune response Include interleukin-1, interleukin-6, tumor necrosis factor, and interferon

Community resources, including homeless shelters, can be used to:

Assist those who are unable to stay cool during warm months and warm during the cold months Individuals can also be encouraged to go to public buildings such as indoor shopping malls or libraries, where ambient temperatures are usually adequately regulated

Hypothermia due to environmental exposure can occur:

At any age, although very young and older adults are at greatest risk

If a heating blanket is used, monitor the patient's skin:

At least every 15 to 30 minutes to reduce the risk for burn injury

Mechanisms of heat loss cause the newborn to:

Be dependent on environmental temperature to keep warm

Immediately after delivery, the infant should:

Be dried quickly, wrapped in blankets, and moved to a heated environment Care should be taken to limit the time the infant's skin is wet (e.g., bathing and wet diapers or clothing)

Unfortunately a number of heat-related deaths among children result from:

Being left in vehicles, in which life-threatening temperatures develop quickly

The hypothalamus is located:

Below the thalamus in an area of the brain called the diencephalon

A newborn is susceptible to rapid heat loss directly after:

Birth Hypothermia may result

Vasoconstriction (narrowing) of blood vessels reduces:

Blood flow to the skin and extremities

However, surface temperature varies, depending on:

Blood flow to the skin and the amount of heat lost to the external environment

Muscle activity requires an increased:

Blood supply and carbohydrate and fat breakdown

Despite extremes in environmental conditions and physical activity, temperature-control mechanisms of humans keep:

Body core temperature (temperature of the deep tissues) relatively constant

A hat is an essential clothing item that significantly decreases:

Body heat loss through the head

Superficial frostbite is easily managed using:

Body heat to warm the affected area Teach patients to place their warm hands over the affected areas on their face or to place cold hands under the arms

Physical activity increases:

Body temperature

Pyrogens such as bacteria and viruses elevate:

Body temperature

Hormonal variations during the menstrual cycle cause:

Body temperature fluctuations

Women generally experience greater fluctuations in:

Body temperature than men

The hypothalamus, located between the cerebral hemispheres, controls:

Body temperature the same way a thermostat works in the home A comfortable temperature is the "set point" at which a heating system operates In the home a drop in environmental temperature activates the furnace, whereas a rise in temperature shuts the system down

The time of day also affects:

Body temperature, with the lowest temperature at 6:00 AM and the highest temperature at 4:00 PM in healthy people

Frostbite occurs when:

Body tissue freezes and causes damage to tissue integrity

Treatment of moderate hypothermia may involve:

Both active external and core (internal) rewarming methods

Wearing too many pairs of socks:

Can decrease circulation and lead to frostbite

Recognize that patients who are severely hypothermic are at high risk for:

Cardiac arrest Respond by avoiding active external rewarming with heating devices because it is dangerous and contraindicated in this population due to rapid vasodilation

If hypothermia is severe, what may be indicated?

Cardiopulmonary bypass or arteriovenous rewarming

A significant increase in body temperature leads to many physiological changes that can be fatal as a result of:

Cardiovascular collapse and damage to the nervous system

Chemical dot thermometers are useful when:

Caring for patients on protective isolation to avoid the need to take electronic instruments into patient rooms

If the body cannot meet the demand for additional oxygen, what occurs?

Cellular hypoxia (inadequate oxygen)

During a fever, what happens?

Cellular metabolism increases, and oxygen consumption rises

Many of these gene mutations are linked to inherited muscle diseases such as:

Central core disease and multi-minicore disease

An infant's temperature responds drastically to:

Changes in the environment

Temperature regulation is unstable until:

Children reach puberty

Several hours pass before the body temperature reaches the new set point. During this period a person experiences:

Chills, shivers, and feels cold, even though the body temperature is rising

When participating in cold-weather activities, what is critical to the prevention of hypothermia and frostbite?

Clothing choices

Evaporative heat loss is five times greater when:

Clothing is wet Thus, dry clothing is essential

Malnutrition and dehydration contribute to:

Cold-related illnesses and injuries

Assess the person at least hourly for the development of:

Compartment syndrome—a limb-threatening complication caused by severe neurovascular impairment

As core body temperature decreases, what occurs?

Compensatory mechanisms including shivering (muscle contraction to simulate warmth) and vasoconstriction (to reduce heat loss) occur Because prolonged vasoconstriction would lead to peripheral tissue ischemia, intermittent reperfusion of peripheral tissues occurs

Once the patient is stabilized, admission to a critical care unit is warranted to monitor for:

Complications such as multi-system organ dysfunction syndrome and severe electrolyte imbalances These problems increase mortality risk

Increased heat loss occurs by:

Conduction This process is not effective, however, if ambient air temperature is greater than body temperature

Applying an ice pack or bathing a patient with a cool cloth increases:

Conductive heat loss

Applying several layers of clothing reduces:

Conductive heat loss

Cerebral hypoxia produces:

Confusion

Infants usually produce sufficient body heat, but they lack the ability to:

Conserve heat produced A large surface area relative to body mass makes them susceptible to excessive temperature loss

The structure of the skin and exposure to the environment result in:

Constant, normal heat loss through radiation, conduction, convection, and evaporation

Solids, liquids, and gases conduct heat through:

Contact

A fan promotes heat loss through:

Convection

A loss of heat by air currents (caused by wind or a fan) moving across the body surface is referred to as:

Convection Warmer air at the body surface is replaced by the cooler air, resulting in cooling of the skin surface Wet skin or clothing accelerates this process

Because the tympanic membrane shares the same arterial blood supply as the hypothalamus, it is a:

Core temperature

Temporal artery temperature is a reliable noninvasive measure of:

Core temperature

Invasive measurements such as with a pulmonary artery catheter are considered:

Core temperatures

Mild to moderate fever generally does little harm and may actually have beneficial effects to:

Counteract the inflammation However, complications such as dehydration and increased metabolic demand can occur

Temporal artery measurements detect the temperature of:

Cutaneous blood flow

What is the drug of choice for MH?

Dantrolene sodium, a skeletal muscle relaxant

Symptoms associated with hyperthermia vary depending on:

Degree of elevated temperature and underlying conditions

Older adults are particularly sensitive to temperature extremes because of:

Deterioration in control mechanisms, particularly: - Poor vasomotor control (control of vasoconstriction and vasodilation) - Reduced amounts of subcutaneous tissue - Reduced sweat gland activity - Reduced metabolism.

If the sweat mechanism has been activated, the individual will be:

Diaphoretic, although this finding may be absent

On a hot, humid day the blood vessels in the hands are:

Dilated and easily visible

The release of TSH-RH is:

Discontinued (thus stopping the T4 and epinephrine responses) And the sympathetic nervous system is signaled to induce vasodilation, decrease muscle tone, and initiate sweat production

The central nervous system may not be functioning properly due to:

Disease or injury

First aid/prehospital care for patients with heat stroke:

Do not give food or liquid by mouth because vomiting and aspiration are risks in patients with neurologic impairment Immediate medical are using advanced life support is essential

Administration of dantrolene intravenously has:

Dramatically reduced the mortality rate of malignant hyperthermia

Survival depends on:

Early diagnosis and the immediate actions of the entire surgical team

Recognition of frostbite is essential to:

Early, effective intervention and prevention of further damage to tissue integrity

Clothing should be layered so it can be:

Easily added or removed as the temperature changes The inner layers, such as polyester fleece, provide warmth and insulation The purpose of the outer layer is to block the wind and provide moisture protection. This layer is best made of a windproof, waterproof, breathable fabric

Oral, rectal, and skin temperature sites rely on:

Effective blood circulation at the measurement site The heat of the blood is conducted to the thermometer probe

Asking a partner to frequently observe for early signs of frostbite such as a white, waxy appearance to exposed skin, especially on the nose, cheeks, and ears is an:

Effective strategy to identify the problem before it worsens

Two types of thermometers are available for measuring body temperature:

Electronic and disposable

Several medical conditions (infections, autoimmune disorders, trauma, and thyroid disturbances) place individuals at risk for:

Elevated body temperature

Recognize that you must monitor patients for the cluster of:

Elevated end-tidal carbon dioxide level, decreased oxygen saturation, and tachycardia to identify symptoms of malignant hyperthermia If these changes begin, respond by alerting the surgeon and anesthesia provider immediately

Heat loss to radiation occurs through a process of electromagnetic waves that:

Emit heat from skin surfaces to the air

In vulnerable patients shivering seriously drains:

Energy sources, resulting in further physiological deterioration

Take extra care to protect newborns from:

Environmental temperatures

Chemical thermogenesis occurs as a result of:

Epinephrine release, which increases metabolic rate

The age, health history, family history (for malignant hyperthermia), and social history provide necessary information to:

Establish risk factors

The body continuously loses heat by:

Evaporation

Wet conditions further increase heat loss through:

Evaporation

Diaphoresis assists in:

Evaporative heat loss

Body metabolism increases 10% for:

Every degree Celsius of temperature elevation

Gangrene may:

Evolve over days to weeks after injury

What Does Evidence Say About On-Site Treatment of Exertional Heat Stroke?

Exertional heat stroke can lead to morbidity and mortality if untreated or undertreated Rapid cooling is cost reasonable and is effective in decreasing morbidity and mortality of patients with heat stroke

Environmental exposure hypothermia occurs from:

Exposure to cold temperature or immersion in cold water It is exacerbated by weather elements such as precipitation, humidity, and wind

Heatstroke occurs as a result of:

Exposure to excessively high temperatures in the environment

If the patient is outside in the cold without warm clothing, body temperature may be low as a result of:

Extensive radiant and conductive heat loss

The treatment of choice for severe hypothermia is to use:

Extracorporeal rewarming methods such as cardiopulmonary bypass or hemodialysis

The primary symptom most commonly associated with hypothermia is:

Feeling cold

The most common exemplar of thermoregulation is:

Fever

The increase or decrease in pyrogen activity results in:

Fever spikes and declines at different times of the day

Patterns of Fever - Remittent

Fever spikes and falls without a return to acceptable temperature levels

Patterns of Fever - Intermittent

Fever spikes interspersed with usual temperature levels Temperature returns to acceptable value at least once in 24 hours

Shelter includes:

Finding shade and ideally a breeze when temperatures are high and avoiding the wind and precipitation when temperatures are low

When water loss through increased respiration and diaphoresis is excessive, the patient is at risk for:

Fluid volume deficit

Wet clothing in particular is a poor insulator and facilitates the development of:

Frostbite

Wet socks and gloves promote:

Frostbite in toes and fingers

Of note, except for frostnip, other degrees of frostbite may all have the same general appearance while the body part is:

Frozen Differentiating features of each degree of frostbite only become apparent after the part is thawed

Signs and symptoms that persist beyond 1 hour require:

Further intervention

More aggressive cooling efforts include:

Gastric or colonic lavage with cool fluids

Muscle rigidity and shivering is typically present in an effort to:

Generate heat

Because susceptibility to MH is inherited (autosomal dominant disorder):

Genetic screening is available and recommended for individuals who have relatives with genetic mutations

The absence of thyroid hormones reduces the BMR by:

Half, causing a decrease in heat production

What should you do when the rewarming process is complete?

Handle the injured areas gently and elevate them above heart level if possible to decrease tissue edema Sometimes splints are used to immobilize extremities during the healing process

In the case of mild, uncomplicated hypothermia as the only health problem, what can aid in rewarming?

Having the victim drink warm high-carbohydrate liquids that do not contain alcohol or caffeine Alcohol is a peripheral vasodilator Both alcohol and caffeine are diuretics These effects can potentially worsen dehydration and hypothermia

The elderly also have a reduced perception of:

Heat and cold They may not recognize when to take appropriate action in a timely manner

Thermoregulation is an aspect of homeostasis that balances:

Heat gain and heat loss

Conduction normally accounts for a small amount of:

Heat loss

Sweat evaporates, resulting in:

Heat loss

The anterior hypothalamus controls:

Heat loss

Perspiration is yet another mechanism involved with:

Heat loss This process is explained by evaporation of moisture from the skin surface

Preterm and newborn hypothermia occurs with:

Heat loss by radiation, evaporation, and conduction

New parents should be instructed about:

Heat loss in newborns and young children Dressing the infant and child appropriately for the weather and adequate regulation of temperature in the home are essential

Wind chill is a significant factor:

Heat loss increases as wind speed rises

The posterior hypothalamus controls:

Heat production

Shivering sometimes increases:

Heat production 4 to 5 times greater than normal

The metabolic rate increases during activity, sometimes causing:

Heat production to increase up to 50 times normal

If the posterior hypothalamus senses that body temperature is lower than the set point, the body initiates:

Heat-conservation mechanisms

Fever, or pyrexia, occurs because:

Heat-loss mechanisms are unable to keep pace with excessive heat production, resulting in an abnormal rise in body temperature

When placed in a warm room a patient may be unable to regulate body temperature by:

Heat-loss mechanisms, and the body temperature may elevate

When the thermoreceptors signal a drop in body temperature, the hypothalamus initiates a series of:

Heat-producing and heat-conserving mechanisms through endocrine and sympathetic nervous system connections

Physical and emotional stress increase body temperature through:

Hormonal and neural stimulation

Strenuous activity in high ambient temperatures, particularly with high humidity, can lead to:

Hyperthermia

Physical exertion in hot conditions increases risk for:

Hyperthermia because the heat gains may exceed heat loss

The homeless population (because of their frequent exposure to the elements and lack of adequate shelter) is particularly at high risk for:

Hyperthermia or hypothermia

Poor nutritional status also places an individual at increased risk for:

Hypothermia

Use a continuous core temperature-monitoring device (e.g., rectal or esophageal probe) or a temperature-monitoring urinary bladder catheter to prevent:

Hypothermia

Maintaining personal fitness and conditioning is also an important consideration to prevent:

Hypothermia and frostbite

Individuals with preexisting medical conditions (e.g., congestive heart failure, diabetes, or gait disturbance) are at increased risk for:

Hypothermia because their bodies have a reduced ability to generate heat

Winter recreational activities such as hiking, snowmobiling, and skiing can lead to:

Hypothermia if an individual has inadequate clothing for the activity or if the individual becomes lost or injured

Cold water exposure also quickly leads to:

Hypothermia, particularly if the air temperature is also cold

Individuals who undergo surgical procedures are also at risk for:

Hypothermia, particularly if the procedure is long

Because alcohol acts as a vasodilator (dilation of surface blood vessels leads to loss of body heat), it is a common underlying factor in:

Hypothermic deaths

Interrelated Concepts

INFECTION is defined as the invasion and multiplication of microorganisms in body tissues, which may be clinically unapparent or result in local cellular injury due to competitive metabolism, toxins, intracellular replication, or antigen-antibody response. When infection is present, physical symptoms often include fever and chills. Because the hypothalamus regulates body temperature, INTRACRANIAL REGULATION is closely associated with thermoregulation. Traumatic brain injury, with its associated cerebral edema, ischemia, energy failure, oxidative stress, and neuronal death, may directly affect the temperature control center. Often, when injury occurs to the brain or spinal cord, there is interruption of the sympathetic nervous system that prevents peripheral temperature sensations from reaching the hypothalamus. PERFUSION is impacted by body temperature. Measures to minimize or maximize heat loss include vasodilation and vasoconstriction within the blood vessels; severe extremes in body temperature can result in cardiovascular collapse. The skin plays an important role in body temperature regulation. The skin acts as a protective layer to reduce heat loss. In addition, thermoreceptors in the skin alert all individuals to extremes in temperatures, thus preventing injury. These mechanisms require intact skin and TISSUE INTEGRITY. Metabolism of nutrients provides the body with fuel needed for the generation of heat and body activities. Malnutrition increases risk for hypothermia because of an inability to generate adequate heat. For this reason, NUTRITION is interrelated with thermoregulation. FLUID AND ELECTROLYTES are affected by thermoregulation. Efficient perspiration requires adequate fluid balances. Fluid and electrolyte imbalances can occur when excessive body temperature exhausts available fluids for perspiration

Seizure activity can further elevate body temperature and is also treated with:

IV benzodiazepine

Internal cooling methods may include:

Iced gastric and bladder lavage

The underlying cause of the elevated body temperature should be:

Identified (e.g., a fever associated with an inflammatory process or hyperthermia associated with exposure)

Temperature-control mechanisms are:

Immature

An environmental temperature below 82° F (28° C) can produce:

Impaired thermoregulation and hypothermia in any susceptible person Therefore people, especially older adults, are actually at risk on a year-round basis in most areas of the world

When nerve cells in the anterior hypothalamus become heated beyond the set point:

Impulses are sent out to reduce body temperature

Because patients experience severe pain during the rewarming process, this intervention is best accomplished:

In a medical facility However, it may be done in another setting if no other options exist for prompt transport or rescue

Does the circadian temperature rhythm change with age?

In general, no

How does the skin control body temperature?

In the human body the internal organs produce heat; during exercise or increased sympathetic stimulation (such as in the stress response) the amount of heat produced is greater than the usual core temperature Blood flows from the internal organs, carrying heat to the body surface The skin has many blood vessels, especially the areas of the hands, feet, and ears Blood flow through these vascular areas of the skin varies from minimal flow to as much as 30% of the blood ejected from the heart Heat transfers from the blood, through vessel walls, to the surface of the skin and is lost to the environment through the heat-loss mechanisms The core temperature of the body remains within safe limits

Where are peripheral thermoreceptors located?

In the skin

Where are central thermoreceptors located?

In the spinal cord, abdominal organs, and hypothalamus

The main risk factor is:

Inadequate insulation against cold weather (i.e., either the skin is exposed to the cold, or the person's clothing offers insufficient protection, leading to injury)

It is characterized by many problems, including:

Inadequate thermoregulation

When large amounts of thyroid hormones are secreted, the BMR can:

Increase 100% above normal

Peripheral vasodilation increases blood flow from the internal organs to the skin to:

Increase radiant heat loss

The goal of managing hypothermic patients is to:

Increase the body temperature to the normal range

The elevated body temperature is thought to:

Increase the production of white blood cells, thus enhancing the immune system response

The reaction begins in skeletal muscles exposed to the drugs, causing:

Increased calcium levels in muscle cells and increased muscle metabolism

Populations living in certain geographical areas in the United States that have hot or cold climates are also at:

Increased risk

Prolonged hypothermia eventually leads to reduced perfusion in the microcirculation attributable to:

Increased viscosity of the blood and reduced blood flow and coagulation

The male sex hormone testosterone:

Increases BMR Men have higher BMR than women

Observe for early manifestations, which include:

Increasing alteration in levels of comfort (pain even after analgesics are given) and paresthesias (painful tingling and numbness)

Infants and young children are also at risk because they are unable to:

Independently take measures to correct changes in temperature They are completely dependent on the appropriate actions of caregivers for maintenance of a normothermic temperature range

The usual temperature range gradually drops as:

Individuals approach older adulthood

Who have less efficient physiological mechanisms for heat production and conservation?

Infants and the elderly

The hypothalamus activates a series of responses to lower or raise body temperature based on:

Information received by the thermoreceptors

Malignant Hyperthermia (MH)

Inherited muscle disorder Is an acute, life-threatening complication of certain drugs used for general anesthesia

If the core temperature is too high, the hypothalamus:

Inhibits vasoconstriction As a result, blood vessels dilate, and more blood reaches the surface of the skin

In contrast, if the core temperature becomes too low, the hypothalamus:

Initiates vasoconstriction, and blood flow to the skin lessens to conserve heat

The body compensates by:

Initiating thermoregulatory mechanisms such as shivering and vasoconstriction, but eventually a hypothermic state occurs if the exposure is extensive in time and/or severity

Second-Degree Frostbite

Involves large clear-to-milky fluid-filled blisters develop with partial-thickness skin necrosis

Malignant hyperthermia is often considered a surgical complication because:

It is actually a biochemical chain reaction triggered by commonly used general anesthetics and succinylcholine

The body gains heat by conduction when:

It makes contact with materials warmer than skin temperature (e.g., application of an aquathermia pad)

Teach the importance of wearing synthetic clothing because:

It moves moisture away from the body and dries fast Cotton clothing, especially as an undergarment, holds moisture, becomes wet, and contributes to the development of hypothermia --- should be strictly avoided in cold outdoor environment

Patients should be advised to dress in:

Layers and cover the head

When metabolism decreases, what happens?

Less heat is produced

Generally, infants and young children, the elderly, and individuals in poor health not only have greater risk factors but also have:

Less physical capacity for physiological compensation when changes in core body temperature occur

For those exposed to the elements, seeking adequate shelter can be:

Life-saving

When the warm skin touches a cooler object, heat is:

Lost

During physical exercise over 80% of the heat produced is:

Lost by evaporation

Dehydration is a serious problem for older adults and children with:

Low body weight

The risk for heat- and cold-related deaths is twice as high for:

Males compared to females Non-Hispanic Blacks have higher rates of heat-related and cold-related deaths than any other race and ethnic group

The use of a drug called dantrolene sodium can reverse the effects of:

Malignant hyperthermia

Intracellular calcium levels are elevated in:

Malignant hyperthermia Dantrolene counteracts this abnormality by reducing muscle tone and metabolism

The only screening mechanism that applies to the concept of thermoregulation is screening for:

Malignant hyperthermia (MH)

A less common risk factor for impaired thermoregulation is genetic predisposition. The classic example of this is:

Malignant hyperthermia, a condition associated with an inherited autosomal dominant pattern

Body temperature changes also occur in women during:

Menopause (cessation of menstruation)

Body heat is continually produced through:

Metabolic activity by chemical reactions occurring in the cells

Activities requiring additional chemical reactions increase:

Metabolic rate

Food is the primary fuel source for:

Metabolism

Any form of exercise increases:

Metabolism and heat production and thus body temperature

These physiological changes increase:

Metabolism, which increases heat production

Heat produced by the body is a by-product of:

Metabolism, which is the chemical reaction in all body cells

Because neonates cannot shiver, a limited amount of vascular brown tissue, present at birth, is:

Metabolized for heat production

Regardless of the cause, the goal is to:

Minimize cardiovascular and neurologic complications associated with excessive body temperature

A reduction in muscle tone and muscle activity occurs as another mechanism to:

Minimize heat production This process explains the fatigue or "washed out" feeling experienced in hot weather or after sitting in a hot tub for a period of time

The hypothalamus senses:

Minor changes in body temperature

The rate of heat loss increases when:

Moistened skin comes into contact with slightly moving air

First priority for collaborative care is to:

Monitor and support patient's airway, breathing, and circulatory status Provide high-concentration oxygen therapy, start several IV lines with 0.9% saline solution, and insert indwelling urinary catheter

It is important to remember that a consistent body temperature measurement from a single site allows you to:

Monitor patterns of your patient's body temperature

Heat loss occurs as a result of:

Multiple mechanisms, including radiation, conduction, convection, vasodilation, evaporation, reduced muscle activity, and increased respiration

What is the most commonly used MH test?

Muscle biopsy tested with the caffeine halothane contracture test (CHCT)

The contraction of muscles produces heat through:

Muscle tone and shivering

Dysrhythmias (e.g., atrial and ventricular fibrillation) may occur due to:

Myocardial irritability

Nonshivering thermogenesis occurs primarily in:

Neonates

Age-Related Differences: Infants

Newborns do not have heat-conserving capacity; thus, thermoregulation is linked closely with metabolism and oxygen consumption The newborn infant has a unique source of heat from brown adipose tissue (or brown fat) This tissue is associated with intensified metabolic activity, thus creating greater heat production capacity compared to normal adipose tissue Brown fat provides an important mechanism for heat production Because newborn infants generally do not shiver, a process referred to as nonshivering thermogenesis (involving increased metabolism and oxygen consumption) helps to offset heat loss Although newborn infants produce sufficient body heat, they have a propensity for heat loss due to a greater body surface area to weight ratio The flexed posture of newborns moderates heat loss somewhat by reducing surface area exposure Another physiological difference leading to newborn heat loss is limited insulation due to a thin layer of subcutaneous fat Blood vessels are closer to the skin, further contributing to heat loss tendencies Thermoregulation becomes more efficient as the infant becomes older Advanced physiological responses to temperature variations emerge that include the ability of muscles to contract, shivering response, vasoconstriction and vasodilation of the capillaries, and increased adipose tissue

A long-standing principle in the treatment of patients with hypothermic cardiac arrest is that:

No one is dead until he or she is warm and dead There is a factual basis to this statement when considering the number of survivors who have suffered a prolonged hypothermic cardiac arrest Prolonged resuscitation efforts may not be reasonable in cases in which survival appears highly unlikely such as in an anoxic event followed by a hypothermic cardiac arrest

Home disposable thermometers are useful for temperature screening but are not as accurate as:

Nondisposable electronic thermometers

Temperature regulation depends on:

Normal heat production processes

Maintaining optimum fluid volume status is an important:

Nursing action

The elderly experience fluctuations in temperature because:

Of a diminished ability to regulate body temperature due to a less effective thermoregulatory response

Cognition is affected because:

Of a gradual reduction in cerebral blood flow

Dehydration may also be associated with elevated body temperature because:

Of the need for fluids to cool the body

Individuals with impairments in cognition (either acute or chronic) are at risk for imbalanced temperature because:

Of the potential inability to recognize dangerous environmental exposures or the inability to react appropriately

Oral temperatures of 35° C (95° F) are sometimes found in:

Older adults in cold weather

If a home does not have air conditioning in the summer months, what is encouraged?

Opening windows and using fans

Chemical dot thermometers are usually for:

Oral temperatures You also use them for rectal temperatures when covered by a plastic sheath and placed for 3 minutes

The most common routes to measure temperature include:

Oral, rectal, auxiliary, temporal artery, and tympanic

Positioning the patient in the supine position prevents:

Orthostatic changes in blood pressure from cardiovascular instability

Weather is the most common cause of hypothermia for:

Outdoor sports enthusiasts and for those with inadequate clothing or shelter It is also a problem for the older adult, the homeless, and the poor who cannot afford heating

The lower temperature persists until:

Ovulation occurs

Interventions during a fever include:

Oxygen therapy

By contrast, frostnip is a type of superficial cold injury that may produce:

Pain, numbness, and pallor or a waxy appearance of the affected area but is easily relieved by applying warmth It does not cause tissue damage

In people with dark skin, skin becomes:

Paler, waxy, and somewhat gray In this case the best remedy is to have the person seek shelter from the wind and cold and attend to the affected body part

Compare the affected extremity with the unaffected one to assess for:

Pallor

People should not diet or restrict food or fluid intake when:

Participating in winter outdoor activities

If hypothermia is mild, what is indicated?

Passive and active external rewarming measures

The condition often occurs when:

Performing physical exertion in a hot environment without proper ventilation

Patterns of Fever - Relapsing

Periods of febrile episodes and periods with acceptable temperature values Febrile episodes and periods of normothermia are often longer than 24 hours

Women who have stopped menstruating often experience:

Periods of intense body heat and sweating lasting from 30 seconds to 5 minutes

In addition to heat production, the body conserves heat through:

Peripheral vasoconstriction This process shunts warm blood away from the superficial body tissues and skin surfaces and increases muscle activity to minimize heat loss

Any previous history of frostbite further increases:

Person's susceptibility

Sweat glands rapidly produce and release increased levels of:

Perspiration Heat dissipates from the body as sweat evaporates from its surface

A person may experience:

Poor coordination and sluggish thought processes at 34°C This progresses to confusion and eventually stupor and coma by the time the temperature decreases to 30°C

These temperature variations help to:

Predict a woman's most fertile time to achieve pregnancy

Additional questions include:

Presence of recent injury, illnesses, or environmental exposure If there has been recent environmental exposure, the type, severity, and length of exposure should be determined

Although this applies for both types of temperature extremes, adequate clothing is essential to:

Prevent hypothermia with cold temperatures

When the patient has a known history for MH, treatment with dantrolene can begin before, during, and after surgery to:

Prevent it

Avoidance of exposure to temperature extremes is an obvious way to:

Prevent problems associated with thermoregulation When this is unavoidable, planning is essential to ensure adequate resources are available

The nurse's role in primary prevention is through:

Primary prevention

The increased metabolism uses energy that:

Produces additional heat

The hypothalamus reacts to raise the set point, and the body responds by:

Producing and conserving heat

Applying external heat with heating blankets can promote core temperature "after-drop" by:

Producing peripheral vasodilation

When exogenous pyrogens invade the body, endogenous pyrogens are released that trigger the production of:

Prostaglandin E2, which in turn elevates the thermal set point and increases core body temperature

When environmental temperature is low, infants should be:

Provided with a hat to guard against heat loss Just as the elderly patient may need a sweater or clothing with long sleeves for comfort

In the critical care setting, what may be used to measure core temperature?

Pulmonary artery catheter

Peripheral vasoconstriction minimizes:

Radiant heat loss

As much as 85% of the surface area of the human body:

Radiates heat to the environment

The patient's position enhances:

Radiation heat loss (e.g., standing exposes a greater radiating surface area, and lying in a fetal position minimizes heat radiation)

Prolonged strenuous exercise such as long-distance running temporarily:

Raises body temperature

For all degrees of partial-thickness-to-full-thickness frostbite:

Rapid rewarming in a water bath at a temperature range of 104° to 108° F (40° to 42° C) is indicated to thaw the frozen part

Therapeutic hypothermia is intentionally induced to:

Reduce metabolism and thereby preserve tissue by preventing tissue ischemia

Resting, maintaining adequate hydration, wearing appropriate clothing, and seeking shelter will help to:

Reduce risk under such conditions

Aspirin is also useful for:

Reducing fever but should be used with caution Aspirin is not recommended for children because of the risk of Reye's syndrome

Most cases of hyperthermia and hypothermia are preventable by:

Reducing risk

Once a patient's frozen part has thawed, do not allow it to:

Refreeze, which worsens the injury

Care of the individual whose temperature has exceeded 37°C should include:

Removal of excess blanketing and clothing while observing for continued signs of hyperthermia (increased respiration, increased or decreased perspiration, high fever, and seizures)

Individuals experiencing significant hypothermia have been known to:

Remove clothing because of reduced cognition and because the vasodilation can create a false warming sensation

An initial step is to:

Remove the individual from the cold

Help promote heat loss through radiation by:

Removing clothing or blankets Covering the body with dark, closely woven clothing decreases the amount of heat lost from radiation

Heat is also lost during the process of:

Respiration Cool ambient air is inhaled and warmed in the respiratory tract and by the microcirculation within the alveoli The warmed air is then exhaled For this reason, elevated respiratory rates are seen among individuals with elevated temperature, and lower respiratory rates are seen in individuals with hypothermia

Thermoregulation involves a negative feedback system, which:

Reverses or opposes a change in a controlled condition

When you find a mercury-in-glass thermometer in the home, teach the patient about:

Safer temperature devices and encourage the disposal of mercury products at appropriate neighborhood hazardous disposal locations

Chemical dot thermometers are useful for:

Screening temperatures, especially in infants, young children, and patients who are intubated

Because of the effects of high body temperature on the brain and central nervous system, what may occur?

Seizures And the patient's cognitive status may range from slightly confused or delirious to coma

Persons under the influence of drugs or alcohol are at risk because:

Sensory alterations affect judgment or there may be a loss of consciousness, thus increasing the risk for environmental exposure

Disease or trauma to the hypothalamus or the spinal cord, which carries hypothalamic messages, causes:

Serious alterations in temperature control

In addition to physical signs and symptoms of infection, fever determination is based on:

Several temperature readings at different times of the day compared with the usual value for that person at that time

Amputation may be indicated for patients with:

Severe injuries or those who develop gangrene or severe compartment syndrome

Care should be taken to not induce:

Shivering

When vasoconstriction is ineffective in preventing additional heat loss, what begins?

Shivering

Heat loss and heat production occur:

Simultaneously

Advantages and Disadvantages of Select Temperature Measurement Sites - Rectal

Site Advantages: - Argued to be more reliable when oral temperature is difficult or impossible to obtain Site Limitations: - Lags behind core temperature during rapid temperature changes - Not for patients with diarrhea, rectal disorders, or bleeding tendencies or those who had rectal surgery - Requires positioning and is often source of patient embarrassment and anxiety - Risk of body fluid exposure and injury to rectal lining - Requires lubrication - Not for routine vital signs in newborns - Readings influenced by impacted stool

Advantages and Disadvantages of Select Temperature Measurement Sites - Tympanic Membrane

Site Advantages: - Easily accessible site - Minimal patient repositioning required - Obtained without disturbing, waking, or repositioning patients - Used for patients with tachypnea without affecting breathing - Sensitive to core temperature changes - Very rapid measurement (2 to 5 seconds) - Unaffected by oral intake of food or fluids or smoking - Used in newborns to reduce infant handling and heat loss - Not influenced by environmental temperatures Site Limitations: - More variability of measurement than with other core temperature devices - Requires removal of hearing aids before measurement - Requires disposable sensor cover with only one size available - Otitis media and cerumen impaction distorts readings - Not used in patients who have had surgery of the ear or tympanic membrane - Does not accurately measure core temperature changes during and after exercise - Does not obtain continuous measurement - Affected by ambient temperature devices such as incubators, radiant warmers, and facial fans - When used in neonates, infants, and children under 3 years old, use care to position device correctly because anatomy of ear canal makes it difficult to position - Inaccuracies reported caused by incorrect positioning of handheld unit

Advantages and Disadvantages of Select Temperature Measurement Sites - Oral

Site Advantages: - Easily accessible—requires no position change - Comfortable for patient - Provides accurate surface temperature reading - Reflects rapid change in core temperature - Reliable route to measure temperature in patients who are intubated Site Limitations: - Causes delay in measurement if patient recently ingested hot/cold fluids or foods, smoked, or is receiving oxygen by mask/cannula - Not for patients who had oral surgery, trauma, history of epilepsy, or shaking chills - Not for infants, small children, or patients who are confused, unconscious, or uncooperative - Risk of body fluid exposure

Advantages and Disadvantages of Select Temperature Measurement Sites - Temporal Artery

Site Advantages: - Easy to access without position change - Very rapid measurement - Comfortable with no risk of injury to patient or nurse - Eliminates need to disrobe or be unbundled - Comfortable for patient - Used in premature infants, newborns, and children - Reflects rapid change in core temperature - Sensor cover not required Site Limitations: - Inaccurate with head covering or hair on forehead - Affected by skin moisture such as diaphoresis or sweating

Advantages and Disadvantages of Select Temperature Measurement Sites - Skin

Site Advantages: - Inexpensive - Provides continuous reading - Safe and noninvasive - Used for neonates Site Disadvantages: - Measurement lags behind other sites during temperature changes, especially during hyperthermia - Adhesion impaired by diaphoresis or sweat - Reading affected by environmental temperature - Cannot be used for patients with allergy to adhesives

Advantages and Disadvantages of Select Temperature Measurement Sites - Axillary

Site Advantages: - Safe and inexpensive - Reliable in stable term and preterm infants Site Limitations: - Long measurement time - Requires continuous positioning - Measurement lags behind core temperature during rapid temperature changes - Not recommended for detecting fever - Requires exposure of thorax that can result in temperature loss, especially in newborns - Affected by exposure to environment, including time to place the thermometer - Underestimates core temperature

You can apply noninvasive chemically prepared thermometer patches to the:

Skin

Peripheral thermoreceptors and central thermoreceptors provide:

Skin and core temperature information to the hypothalamus

Frostnip typically develops on:

Skin areas such as the face, nose, finger, or toes Untreated, it is a precursor to more severe forms of frostbite

Excessive evaporation causes:

Skin scaling and itching and drying of the nares and pharynx

Age-Related Differences: Older Adults

Slower circulation, including decreased vasoconstrictor responses, reduced function of thermoregulatory capacity of the skin (including decreased or absent sweating), and reduced heat production (associated with slower metabolic and physical activity), decreased shivering response, and reduced perception of environmental temperature are seen among older adults

Core rewarming should be done:

Slowly and carefully to minimize the risk of triggering dysrhythmias Continuous cardiac monitoring and core body temperature observation are necessary

Excessive and prolonged sweating coupled with a sustained high body temperature can result in:

Sodium loss and dehydration if fluid replacement does not occur

However, axillary measurements have been shown to be as reliable as rectal temperature measurement in:

Stable infants

During a febrile episode white blood cell production is:

Stimulated

Fever also fights viral infections by:

Stimulating interferon, the natural virus-fighting substance of the body

Another form of electronic thermometer measures the temperature of the:

Superficial temporal artery

The body redistributes blood to:

Surface vessels to promote heat loss

A lowered body temperature inhibits:

Sweat gland secretion

A handheld scanner with an infrared sensor tip detects the temperature of cutaneous blood flow by:

Sweeping the sensor across the forehead and just behind the ear

Shivering is an involuntary body response to:

Temperature differences in the body The skeletal muscle movement during shivering requires significant energy

Infants (particularly premature infants) have undeveloped:

Temperature regulation capacity

At birth the newborn leaves a warm, relatively constant environment and enters one in which:

Temperatures fluctuate widely

Thyroid hormones also affect:

The BMR

The hypothalamus also stimulates the sympathetic nervous system, which triggers:

The adrenal cortex to increase muscle tone and initiate a shivering and vasoconstriction response

The degree of vasoconstriction determines:

The amount of blood flow and heat loss to the skin

Body temperature is the difference between:

The amount of heat produced by body processes and the amount lost to the external environment

Thyrotropin (or thyroxine)-stimulating hormone-releasing hormone (TSH-RH) is secreted by the hypothalamus, which in turn stimulates:

The anterior pituitary to release thyroid-stimulating hormone

Individuals who have experienced traumatic brain injury are at risk for problems with thermoregulation, particularly if:

The area of the brain damaged leads to hypothalamic dysfunction

Cool packs may be placed in:

The axillary and groin areas A cooling blanket or lukewarm bath may also facilitate temperature reduction

Physiological and behavioral mechanisms regulate:

The balance between heat lost and heat produced, or thermoregulation

Basal metabolism accounts for the heat produced by:

The body at absolute rest

The average basal metabolic rate (BMR) depends on:

The body surface area

When progesterone levels are low, what happens?

The body temperature is a few tenths of a degree below the baseline level

Hyperthermia occurs when:

The body temperature rises above 37.6°C with an unchanged hypothalamic set point

During ovulation greater amounts of progesterone enter the circulatory system and raise:

The body temperature to previous baseline levels or higher

The heat that is produced helps equalize:

The body temperature, and the shivering ceases

Fever patterns differ, depending on:

The causative pyrogen

After-Drop

The continued decrease in core body temperature after the victim is removed from the cold environment It is caused by the return of cold blood from the periphery to the central circulation Therefore the patient's trunk should be actively rewarmed before the extremities

Management of the patient with altered thermoregulation is dependent on:

The core body temperature and the overall physical condition of the individual

Hypothermia occurs when:

The core body temperature declines below 36.2°C Is further classified as: - Mild (34-36°C or 93.2-96.8° F) - Moderate (30-34°C or 86-93°F) - Severe (<30°C or <86°F)

The shivering response diminishes or ceases when:

The core temperature decreases to 30°C

Intensive care units use:

The core temperatures of the pulmonary artery, esophagus, and urinary bladder These measurements require the use of continuous invasive devices placed in body cavities or organs and continually display readings on an electronic monitor

Additional core temperature sites include:

The esophagus and urinary bladder

Cardiopulmonary bypass is:

The fastest core rewarming technique

Increased temperature reduces the concentration of iron in the blood plasma, suppressing:

The growth of bacteria

A newborn loses up to 30% of body heat through:

The head and therefore needs to wear a cap to prevent heat loss

Specifically, pyrogens trigger:

The hypothalamus to increase the thermostatic set point

Physiological adjustments to body temperature are controlled by:

The hypothalamus—often considered the thermostat center of the body The nurse uses the average target temperature of 37°C (98.6°F) to assess this state

Fever represents a complex pathophysiological reaction involving:

The immune system in response to pyrogens (fever-producing agents) that trigger the hypothalamus in the brain to adjust heat production, heat conservation, and heat loss mechanisms to maintain a higher core temperature, representing an increased hypothalamic set point

Fever is a temporary elevation in body temperature caused by:

The immune system's release of endogenous pyrogens (a protein produced by leukocytes) in response to an invasion of bacteria, viruses, fungi, toxins, or drugs

Malignant hyperthermia (MH) is a hypermetabolic disorder of skeletal muscle triggered by:

The induction of anesthetic agents and leads to severe hyperthermia

Metabolic activity involves:

The ingestion and metabolism of food and the basal metabolic rate—or the energy required to maintain the body at rest

Progesterone levels rise and fall cyclically during:

The menstrual cycle

Heart and respiratory rates increase to meet:

The metabolic needs of the body for nutrients

As hypothermia progresses, what occurs?

The metabolic rate declines and perfusion of blood is significantly reduced, leading to diminished urinary function, coma, and cardiovascular collapse

This is a small but important part of the brain located between:

The midbrain and cerebrum

Use a thermometer to obtain intermittent temperature measurements from:

The mouth, rectum, tympanic membrane, or temporal artery

The chill phase resolves when:

The new set point, a higher temperature, is achieved

Radiation heat loss can be considerable during surgery when:

The patient's skin is exposed to a cool environment However, if the environment is warmer than the skin, the body absorbs heat through radiation

Thermoregulation

The process of maintaining core body temperature at a near constant value

Tympanic temperature relies on:

The radiation of body heat to an infrared sensor

By promoting the breakdown of body glucose and fat, thyroid hormones increase:

The rate of chemical reactions in almost all cells of the body

What happens when the thermoreceptors signal an increase in body temperature?

The same mechanisms are reversed (the classic feature of a negative feedback system)

The physiological consequences of hypothermia are dependent on:

The severity and duration of exposure

Treatment decisions are based on:

The severity of hypothermia

Approximately 600 to 900 mL a day evaporates from:

The skin and lungs, resulting in water and heat loss

Vasodilation occurs, causing:

The skin to appear flushed and warm or hot to touch

Peripheral vasoconstriction causes:

The skin to feel cool and have slow capillary refill Skin color is pale and becomes cyanotic

Most heat-related deaths occur in:

The southern and western states

Normothermia

The state in which body temperature is within the "normal" range

The duration and degree of fever depend on:

The strength of the pyrogen and the ability of the individual to respond

Axillary temperatures are reflective of:

The surface temperature of the body

When body temperature rises, the anterior hypothalamus signals:

The sweat glands to release sweat through tiny ducts on the surface of the skin

Radiation increases as:

The temperature difference between the objects increases

If the new set point is "overshot" or the pyrogens are removed (e.g., destruction of bacteria by antibiotics), what occurs?

The third phase of a febrile episode occurs

Convection

The transfer of heat away by air movement

Evaporation

The transfer of heat energy when a liquid is changed to a gas

Conduction

The transfer of heat from one object to another with direct contact

Radiation

The transfer of heat from the surface of one object to the surface of another without direct contact between the two

An otoscope-like speculum with an infrared sensor tip detects heat radiated from:

The tympanic membrane

The older adult has a narrower range of body temperatures than:

The younger adult

Environmental temperatures affect infants and older adults more often because:

Their temperature-regulating mechanisms are less efficient

Elderly who lack resources to stay warm or cool in temperature extremes are also at risk for:

Thermodysregulation

Recognize that dry heat or massage should not be used as part of the warming process for frostbitten areas because:

These actions can produce further damage to tissue integrity Respond by using other interventions such as a rapid rewarming water bath of 104° to 108° F (40° to 42° C), to preserve tissue

Axillary temperature measurements, obtained by placing a thermometer under the axillae, are not recommended in adults because:

They have been shown to be inaccurate and poorly reflect core temperature

Single-use or reusable chemical dot thermometers are:

Thin strips of plastic with a temperature sensor at one end The sensor consists of a matrix of chemically impregnated dots that change color at different temperatures

Exogenous Pyrogens

Those of external origin Include bacterial endotoxins, viruses, antigen-antibody complexes, etc.

Thyroid-stimulating hormone acts on the thyroid gland to release:

Thyroxine (T4), which activates the adrenal medulla to cause the release of epinephrine into the blood

In cases of severe, deep frostbite, debridement of necrotic tissue may be needed to evaluate:

Tissue viability and provide wound management

Hydration, nutritional support, and other palliative measures:

To reduce core temperature should be implemented

People who have a congenital absence of sweat glands or a serious skin disease that impairs sweating are unable to:

Tolerate warm temperatures because they cannot cool themselves adequately

Because they often underestimate oral temperature by 0.4° C (0.7° F) or more, use electronic thermometers to confirm measurements made with a chemical dot thermometer when:

Treatment decisions are involved

How many types of pyrogens are there?

Two

Cold-Related Injuries

Two common cold-related injuries are from hypothermia and frostbite

Another form of electronic thermometer is used exclusively for:

Tympanic temperature

Temperature measurement among infants and children can be accomplished with:

Tympanic thermometer, oral thermometer (a pacifier thermometer), axillary, or temporal artery Although the temporal artery method may not be as reliable in children younger than age 2 years

Preterm infants are often kept:

Under a radiant warmer or in an incubator with protection from draft air

Typically, a history does not include specific questions related to normal body temperature or thermoregulation. However, in the event of thermoregulation imbalance, a history provides:

Valuable information needed to understand the problem

The hypothalamus set point drops, initiating heat-loss responses. The skin becomes warm and flushed because of:

Vasodilation

Also, the vasoconstrictive efforts controlled by the hypothalamus eventually fail, causing:

Vasodilation and thus accelerating the loss of body heat

Protect patients from further heat loss and handle them gently to prevent:

Ventricular fibrillation

Diaphoresis

Visible perspiration primarily occurring on the forehead and upper thorax, although you can see it in other places on the body

Compensatory heat production is stimulated through:

Voluntary muscle contraction and muscle shivering

During the next phase, the plateau, the chills subside, and the person feels:

Warm and dry

Increasing physical activity helps to:

Warm the body when exposed to low temperatures and can prevent hypothermia

If home heating is inadequate during cold weather, patients should be advised to:

Wear adequate and/or additional clothing and use blankets for additional warmth Wind drafts should be blocked and curtains hung at windows to improve insulation

Highest cold-related death rates occur in:

Western states

There is also a genetic test that is performed on blood to assess:

Whether a mutation in the RYR1 gene is present

Face protection with a facemask should be used on particularly cold days when:

Wind chill poses a risk

The problem is most common in:

Young adult males (despite the autosomal-dominant pattern of inheritance) because of gender differences in muscle mass

Basal metabolic rate tends to be higher among:

Younger individuals and decreases as the body ages Food consumption, physical activity, and hormone levels affect the amount of heat produced

Follow standard resuscitation efforts with special attention to maintenance of airway, breathing, and circulation as recommended by the American Heart Association:

• Administer drugs with caution and/or spaced at longer intervals because metabolism is unpredictable in hypothermic conditions • Remember that drugs can accumulate without obvious therapeutic effect while the patient is cold but may become active and potentially lead to drug toxicity as effective rewarming is under way • Consider withholding IV drugs, except vasopressors, until the core temperature is above 86° F (30° C) • Initiate CPR for patients without spontaneous circulation • For a hypothermic patient in ventricular fibrillation or pulseless ventricular tachycardia, one defibrillation attempt is appropriate. Be aware that defibrillation attempts may be ineffective until the core temperature is above 86° F (30° C)

Medical Conditions as Risk Factors for Altered Thermoregulation

• Autoimmune conditions • Burns • Chronic medical conditions • Hypothalamic injury (traumatic brain injury; stroke; brain neoplasm) • Infection • Inflammation • Long surgical procedures • Metabolic conditions (hyperthyroidism; hypothyroidism) • Prematurity/preterm birth • Protein calorie malnutrition • Traumatic injury

Nursing Focus on the Older Adult - Heat-Related Illness Prevention

• Avoid alcohol and caffeine • Prevent overexposure to the sun; use a sunscreen with an SPF of at least 30 with UVA and UVB protection • Rest frequently and take breaks from being in a hot environment. Plan to limit activity at the hottest time of day • Wear clothing suited to the environment. Lightweight, light-colored, and loose-fitting clothing is best • Pay attention to your personal physical limitations; modify activities accordingly • Take cool baths or showers to help reduce body temperature • Stay indoors in air-conditioned buildings if possible • Ask a neighbor, friend, or family member to check on the older adult at least twice a day during a heat wave

Key Features of Severe Hypothermia:

• Bradycardia • Severe hypotension • Decreased respiratory rate • Cardiac dysrhythmias, including possible ventricular fibrillation or asystole • Decreased neurologic reflexes • Decreased pain responsiveness • Acid-base imbalance

Common predisposing conditions that promote hypothermia include:

• Cold-water immersion • Acute illness (e.g., sepsis) • Traumatic injury • Shock states • Immobilization • Cold weather (especially for the homeless and people working outdoors) • Advanced age • Selected medications (e.g., phenothiazines, barbiturates) • Alcohol intoxication and substance abuse • Malnutrition • Hypothyroidism • Inadequate clothing or shelter (e.g., the homeless population)

Key Features of Moderate Hypothermia:

• Muscle weakness • Increased loss of coordination • Acute confusion • Apathy • Incoherence • Possible stupor • Decreased clotting (caused by impaired platelet aggregation and thrombocytopenia)

Key Features of Mild Hypothermia

• Shivering • Dysarthria (slurred speech) • Decreased muscle coordination • Impaired cognition ("mental slowness") • Diuresis (caused by shunting of blood to major organs)

Emergency Care of the Patient With Malignant Hyperthermia:

• Stop all volatile inhalation anesthetic agents and succinylcholine • If an endotracheal tube (ET) is not already in place, intubate immediately • Ventilate the patient with 100% oxygen at the highest possible flow rate to flush anesthetics and lower end-tidal carbon dioxide • Administer dantrolene sodium (Dantrium) IV at a dose of 2 to 3 mg/kg. Repeat as needed • If possible, terminate surgery. If termination is not possible, maintain general anesthesia with IV anesthetic agents that do not trigger malignant hyperthermia (MH) (IV sedatives, narcotics, amnestics and nondepolarizing neuromuscular blockers) • Assess arterial blood gases (ABGs) and serum chemistries for metabolic acidosis and hyperkalemia • If metabolic acidosis is evident by ABG analysis, administer sodium bicarbonate IV • If hyperkalemia is present, administer 10 units of regular insulin in 50 mL of 50% dextrose IV • Administer iced saline (0.9% NaCl) IV at a rate of 15 mL/kg every 15 minutes as needed • Apply a cooling blanket over the torso • Pack bags of ice around the patient's axillae, groin, neck, and head • Lavage the stomach, bladder, rectum, and open body cavities with sterile iced normal saline • Insert a nasogastric tube and a rectal tube • Monitor core body temperature to assess effectiveness of interventions and avoid hypothermia • Monitor cardiac rhythm by electrocardiography (ECG) to assess for dysrhythmias • Insert a Foley catheter to monitor urine output • Treat any dysrhythmias that do not resolve on correction of hyperthermia and hyperkalemia with antidysrhythmic agents. Avoid calcium channel blockers • Administer intravenous fluids at a rate and volume sufficient to maintain urine output above 2 mL/kg/hr • Monitor urine for presence of blood or myoglobin • If urine output falls below 2 mL/kg/hr, consider using osmotic or loop diuretics, depending on the patient's cardiac and kidney status • Contact the Malignant Hyperthermia Association of the United States (MHAUS) hotline for more information regarding treatment: (800) 644-9737 • Transfer the patient to the intensive care unit (ICU) when stable • Continue to monitor the patient's temperature, ECG, ABGs, electrolytes, creatine kinase, coagulation studies, and serum and urine myoglobin levels until they have remained normal for 24 hours • Instruct the patient and family about testing for MH risk • Refer the patient and family to the Malignant Hyperthermia Association of the United States at (800) 986-4287 or www.mhaus.org • Report the incident to the North American Malignant Hyperthermia Registry at the Malignant Hyperthermia Association of the United States: (800) 644-9737