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