Pathophysiology: Chapter 33- Disorders of Thermoregulation

The nurse is caring for a homeless patient with hypothermia after spending a cold night on a park bench. Which statement correctly explains why shivering did not prevent hypothermia in the patient? a. "Shivering increased the metabolic rate and eventually promoted heat loss." b. "The patient had an underlying condition that prevented shivering." c. "Shivering prompted the hypothalamus to reduce the core body temperature set point." d. "Heat was lost through eccrine sweat as a result of the shivering."

a. "Shivering increased the metabolic rate and eventually promoted heat loss." The heat generated by shivering tends to be ineffective in cold environments because the oxygen consumption with shivering increases the metabolic rate 3-5 times over the resting rate. The muscle contractions eventually promote heat loss by increasing blood flow to the skin, perfusing cooler vascular regions, and creating convective currents through movement. Shivering does not result in heat loss through eccrine sweat. Shivering does not cause the hypothalamus to reduce the set point. There is no indication of an underlying condition that prevented shivering.

The school nurse is caring for a child who forgot their coat at home and stood at the bus stop in a chilly drizzling rain. The child's temperature is 34°C (93.2°F). Which finding is the nurse least likely to assess in this child? a. Bradycardia b. Tachycardia c. Clumsiness d. Shivering

a. Bradycardia Bradycardia is not expected with mild hypothermia. Expected clinical manifestations of mild hypothermia include shivering, clumsiness, and tachycardia not bradycardia. Other clinical manifestations of mild hypothermia include confusion, tachypnea, and a decrease in body temperature.

Central thermoreceptors are activated by core body temperatures high enough to cause permanent neural damage, coma, and death. Which area of the brain is responsible for regulation of body temperature? a. Hypothalamus b. Pituitary c. Thalamus d. Hippocampus

a. Hypothalamus The hypothalamus is responsible for regulating body temperature. The hippocampus is involved in memory storage. The pituitary releases hormones into the bloodstream. The thalamus is involved in sensory and motor signal relay and the regulation of consciousness and sleep. Additional Learning Some aspects of the peripheral thermoreceptors include: They exist near the surface of the body in the skin and the oral and urogenital mucosa. Most peripheral thermoreceptors are cold-sensitive. Cutaneous cold sensors are located just beneath the skin. Warm sensors are located deeper in the dermis.

The nurse is teaching a group of new parents in the community about safety risks in infants. Which mechanism places full-term infants at risk for heat stress? a. Limited vasodilation capabilities b. Hypermetabolism c. Dehydration d. Increased cytokine release

a. Limited vasodilation capabilities Full-term infants are at a high risk for hyperthermia and heat stress because of a limited ability to adapt to the heat by means of vasodilation. Increased cytokine release, hypermetabolism, and dehydration are not common reasons for full-term infants to be at high risk for hyperthermia. Additional Learning Other groups at risk for heat-related illnesses include the following: Older adults Marathon runners in warm climates Football players during workouts Basic military trainees Sedentary individuals engaged in physical exertion

The nurse is caring for a patient who fell into a lake on a chilly spring day. The patient is not shivering, has fluid shifting into third spaces, and has signs of impaired glycemic autoregulation and decreased renal blood flow. Which health problem should the nurse plan care for this patient? a. Moderate hypothermia b. Deep hypothermia c. Profound hypothermia d. Mild hypothermia

a. Moderate hypothermia Absence of shivering, fluid shift into third spaces, signs of impaired glycemic autoregulation, and decreased renal blood flow are clinical manifestations of moderate hypothermia. Together, these clinical manifestations do not indicate mild hypothermia, deep hypothermia, or profound hypothermia. Additional Learning

The nurse is caring for a patient with profound hypothermia. Which clinical manifestation should the nurse expect to assess? a. Vigorous shivering b. Absence of neurological reflexes c. Shallow respirations d. Hyperventilation

b. Absence of neurological reflexes Absence of neurological reflexes is a clinical manifestation of profound hypothermia. Vigorous shivering and hyperventilation indicate mild hypothermia. Shallow respirations are seen with moderate hypothermia.

The nurse is caring for a patient with severe hypothermia. Which instruction should the nurse include in the patient's plan of care? a. Monitor cardiac telemetry. b. Apply heat packs to extremities. c. Vigorously rub the patient's hands and feet. d. Prepare to rewarm the patient quickly.

a. Monitor cardiac telemetry. Monitoring cardiac telemetry is an appropriate plan of care. Vigorously rubbing the patient's extremities, applying heat packs to the extremities, and rewarming the patient quickly can all increase the risk of cardiac dysrhythmias. Additional Learning Care of a patient with hypothermia includes: Transport to a well-equipped emergency facility is critical. Handle gently. Apply warm dry clothing. Avoid actions that cause cardiac dysrhythmias such as rapid warming, intubation, or stimulation. Use warm fluid infusions and warm humidified air to rewarm.

The nurse is caring for an older adult patient diagnosed with moderate hypothermia. Which consideration should be a priority for the patient's safety? a. Provide gentle handling to avoid dysrhythmia. b. Remove clothing to prepare for radiant heating. c. Monitor for cardiac irritability before rewarming begins. d. Prepare for immediate therapeutic hypothermia.

a. Provide gentle handling to avoid dysrhythmia. Gentle handling is essential for a patient with signs and symptoms of moderate to profound hypothermia because rough handling can trigger ventricular fibrillation. The patient should be given warm, dry clothing. Cardiac monitoring is essential because raising the core temperature may induce temperature-related cardiac irritability. Therapeutic hypothermia is not indicated. Additional Learning Aging affects the body's ability to regulate temperature due to factors such as: Older adults are at risk for hypothermia because of a decreased ability to generate or conserve heat. Older adults are also at risk for hyperthermia in hot, humid environments because they may have a decreased ability to lose heat.

The nurse is caring for a patient with mild hypothermia. Which clinical manifestations should the nurse expect to assess? a. Shivering, cyanosis, and confusion b. Hypoglycemia, goose bumps, and acute symptoms c. Bradycardia, agonal respirations, and a decreased core body temperature d. Tachycardia, tachypnea, and an increase in body temperature

a. Shivering, cyanosis, and confusion Expected clinical manifestations of mild hypothermia include shivering, confusion, and cyanosis. Other clinical manifestations of mild hypothermia include tachycardia, tachypnea, and a decrease in body temperature. Hyperglycemia, goose bumps, and acute symptoms are at first vague. Bradycardia and agonal respirations are not seen in mild hypothermia. A decreased core body temperature is also a common symptom of mild hypothermia.

After a myocardial infarction, a patient is placed under a cooling blanket for therapeutic hypothermia. Which instruction should the nurse include in the patient's plan of care? a. Wrap or pad fingers, toes, and bony prominences. b. Assess for fixed and dilated pupils. c. Monitor for respiratory and metabolic acidosis. d. Handle gently.

a. Wrap or pad fingers, toes, and bony prominences. Wrapping or padding of fingers, toes, and bony prominences will protect the patient from frostbite-like injury. Cardiac dysrhythmias are more likely with severe unexpected hypothermia. Metabolic and respiratory acidosis are symptoms of profound hypothermia. Fixed and dilated pupils are signs of deep hypothermia. Additional Learning Individuals at risk for frostbite include the following: Individuals exposed to freezing temperatures Soldiers required to march for long periods with their feet submerged in cold water Individuals rescued from submersion in water Homeless individuals Individuals who are on or under surface cooling blankets

The nurse is explaining to a patient how the human body is susceptible to changes in environmental temperature, as well as to internal changes that may affect core body temperature. Which combination of factors should the nurse identify that may put a patient's body temperature at risk? a. Sedentary lifestyle and fungal infection b. Acclimatization and systemic physiological processes c. Joint disorders and blood dyscrasias d. An allergic reaction to a medication

b. Acclimatization and systemic physiological processes Acclimatization and systemic physiological processes put the body's thermoregulatory system at risk. Sedentary lifestyle, fungal infections, joint disorders, blood dyscrasias, and allergic reactions normally do not affect the body's thermoregulatory system. Additional Learning The thermoeffector threshold zone is the range of acceptable core temperature. The range is not fixed, meaning that it can be altered by illness, acclimatization, and other physiological processes. Peripheral and central thermoreceptors detect the core body temperature. A core body temperature above or below the threshold triggers a physiological response as the body works to move the core temperature back into the acceptable range.

The nurse is caring for a young woman found wandering in the rain with a head injury. Which symptom should the nurse be especially vigilant about in the patient? a. Alteration in urine output b. Alteration in thermoregulation c. Excessive coughing d. Evidence of sexual abuse

b. Alteration in thermoregulation The nurse should be especially vigilant for alterations in thermoregulation. Excessive coughing is only significant if the patient has a head trauma causing symptoms of neurological dysfunction. Each patient must be assessed for evidence of sexual abuse on admission to an inpatient care facility. An alteration in urine output may indicate a renal problem. Additional Learning Risk factors for hypothermia include the following: Neonatal complications Preterm birth and low birth weight Birth asphyxia Sepsis or respiratory distress Birth en route to hospital Exposure to cold Trauma Impaired thermoregulation Anesthesia Advanced age Lean body mass Illnesses Paralysis, especially with high spinal cord injury Impaired communication or loss of coordination, such as that in stroke Hypothyroidism Diabetes

A patient who was shoveling snow without gloves has white and waxy appearing fingertips. Which appearance of the fingertips should the nurse expect in 2 weeks? a. Blistered b. Black c. White and waxy d. Purple and bruised

b. Black Treatment for frostbite includes: Restore perfusion to the viable tissue. Keep the area clean to prevent infection. Prevent mechanical injury. Hyperbaric oxygen therapy may be prescribed to preserve fingers and toes. Thrombolytic therapy may be used to improve circulation.

The nurse is caring for a child who sustained second-degree burns after pulling a hot skillet off the stove. Which mechanism caused the burns? a. Convection b. Conduction c. Evaporation d. Radiation

b. Conduction Conduction is the process of heat transfer through contact with a hot or cold surface. Convection is the transfer of heat with the movement of air across the skin, such as that which occurs when you sit under a fan. Radiation is the transfer of heat through infrared rays. Radiation is a transfer of heat with no contact, such as that which occurs when you are exposed to the sun for extended periods. Evaporation refers to the loss of heat through the conversion of water to gas, which happens when sweat evaporates.

The nurse plans interventions to prevent the development of hypothermia in a 2-day-old infant weighing 3 lb 10 oz. Which statement explains the rationale for this risk? a. Maternal drug use induces hypothermia in infants. b. Decreased subcutaneous fat and a high potential for central heat loss increase the risk for hypothermia. c. Susceptibility to infection increases the risk for hypothermia. d. The medications used for preterm infants increase the risk of hypothermia.

b. Decreased subcutaneous fat and a high potential for central heat loss increase the risk for hypothermia. Decreased subcutaneous fat and a high potential for central heat loss make a low-birth-weight infant more vulnerable to the effects of hypothermia. Susceptibility to infection, medications, and maternal drug use are not common causes of hypothermia in low-birth-weight infants. Additional Learning Therapeutic hypothermia is used to reduce swelling and neural oxygen demand, improving survival outcomes in patients who sustain a stroke, myocardial infarction, traumatic brain injury, or heatstroke.

Which is the best treatment for a patient experiencing heat exhaustion? a. Move the patient to a cool environment and offer cool water. b. Move the patient to a cool environment and offer electrolyte replacement fluids. c. Do not allow the patient to rest. d. Move the patient to a shaded area and offer cool water.

b. Move the patient to a cool environment and offer electrolyte replacement fluids. The patient should be moved to a cool environment and offered electrolyte replacement fluids. Offering water without electrolytes can result in hyponatremia. The patient should be under close supervision and allowed to rest. If symptoms do not resolve within 20-30 minutes, the patient should be considered to have heatstroke.

The nurse is explaining to a patient with a fever that headache may result from the increased core temperature. Which physiological process should the nurse identify as the cause of this pain? a. Decreased blood pressure b. Pro-inflammatory cytokines c. Nausea d. Cerebral vasoconstriction

b. Pro-inflammatory cytokines Headache occurs as a result of the molecular activities of circulating pro-inflammatory cytokines. Vasoconstriction of cerebral vessels does not occur with hyperthermia. Decreased blood pressure may occur with prolonged hyperthermia but does not trigger headache. Nausea does not cause headache. Additional Learning Pro-inflammatory cytokines are released by phagocytes, fibroblasts, and endothelial cells in response to a pyrogen. Cytokines shift the set point upward, resulting in physiological responses to increase core body temperature. There are three phases to fever: Chill phase, as the body works to increase core body temperature Plateau phase, when the body maintains the new set point Defervescence phase, when cytokine levels fall and the set point returns to normal

A patient has had a high fever for 3 days and is experiencing a new onset of altered consciousness and muscle rigidity. Which question should the nurse immediately ask the patient? a. "What herbal remedies do you take?" b. "Have you been exposed to tuberculosis?" c. "Do you take any antipsychotic medications such as haloperidol?" d. "When was the last time you took cocaine?"

c. "Do you take any antipsychotic medications such as haloperidol?" Neuroleptic malignant syndrome should be suspected when a patient has intractable hyperthermia, muscle rigidity, autonomic dysfunction, and altered consciousness. Two of the four symptoms must be present for 1 to 3 days. Neuroleptic malignant syndrome is a reaction to neuroleptic antipsychotics and tranquilizers. Cocaine, herbal remedies, and tuberculosis do not cause these symptoms. Additional Learning Neuroleptic drugs are also given for anesthetic analgesia and to treat asthma. Other conditions with similar symptoms should be ruled out, including: Malignant hyperthermia Malignant catatonia Serotonin syndrome

The nurse suspects that a patient who is shivering is entering the chill phase of a fever. Which reason explains why the patient is shivering? a. Pyrogens stimulate the hypothalamus to decrease the core temperature set point. b. Cytokine levels fall in response to the introduction of a pyrogen. c. Cytokines stimulate the hypothalamus to increase the core temperature set point, which causes the body to generate and conserve heat. d. Chills stop as the body generates heat through severe shivering.

c. Cytokines stimulate the hypothalamus to increase the core temperature set point, which causes the body to generate and conserve heat. The introduction of pyrogens stimulates monocytes and macrophages to release cytokines, which in turn prompt the hypothalamus to increase the core temperature set point, resulting in generation and conservation of heat. Pyrogens do not stimulate the hypothalamus to decrease the set point. Cytokine levels do not fall at this phase. Chills do not stop at this point. Additional Learning Cautious evaluation of rising temperatures is important. However, it is also important to note that when an individual has a fever, thermoregulation is intact. Cooling the body will cause shivering and vasoconstriction and will make core temperature rise even higher.

A patient with a bacterial infection who is being treated with antibiotics begins to sweat profusely and complains of being hot. Which instruction should the nurse include in the patient's plan of care? a. Prepare for therapeutic hypothermia. b. Lower the patient's room temperature. c. Protect the patient from abrupt temperature changes. d. Give the patient a cool bath.

c. Protect the patient from abrupt temperature changes. The patient is in the defervescence phase of fever. Although the temperature set point is lowering, the patient is still very sensitive to abrupt temperature changes. Therapeutic hypothermia, cool baths, and decreased room temperature are not appropriate interventions for a patient in the defervescence phase. Additional Learning The three phases of fever. This schematic shows the typical febrile episode, which is typified by three phases and closely associated with cytokine levels. When they rise, they induce the chill phase, causing the body temperature to rise to the new thermoneutral range. Even when the core temperature is 39°C, if the set point moves higher, the person will shiver and feel cold. In this phase, febrile shivering is most likely to occur. The plateau phase follows, in which chills stop and the warm body temperature is not particularly distressful. When the cytokine levels fall, so does the set point level, and the warm body temperature becomes unbearably hot. The patient kicks off the covers but is still sensitive to abrupt temperature changes. A draft or cool bath may elicit more shivering.

The nurse is caring for a homeless patient who has spent the night outside in a snowstorm. Which clinical manifestation is least likely to occur in this patient? a. Absence of muscle reflexes b. No muscle rigidity c. Vigorous shivering d. Decreased nerve conduction

c. Vigorous shivering Vigorous shivering is a clinical manifestation of mild hypothermia. The patient in this scenario is most likely suffering from deep hypothermia. Absence of muscle reflexes, decreased nerve conduction, and absence of muscle rigidity are all clinical manifestations of deep hypothermia.

The nurse notes that a patient is shivering while waiting for a diagnostic test. Which statement should the nurse consider about the effect of shivering in cold environments? a. "The oxygen consumption required for shivering decreases the metabolic rate." b. "Shivering is a very effective mechanism to generate heat in cold environments." c. "Shivering creates convective currents through movement to prevent heat loss." d. "Shivering in cold environments actually promotes heat loss due to increased blood flow to the skin."

d. "Shivering in cold environments actually promotes heat loss due to increased blood flow to the skin." Shivering in cold environments promotes heat loss due to increased blood flow to the skin, perfusing of cooler regions of the body, and creating convective currents through movement. Shivering increases the metabolic rate 3-5 times over resting metabolic rate. Therefore, it is not an effective method of generating and retaining heat in cold environments.

Which definition describes the process by which a body gains heat while sitting on heated car seat on a winter day? a. Convection b. Evaporation c. Radiation d. Conduction

d. Conduction In conduction, heat is transferred through contact with a hot or cold surface. Convection is when heat is transferred by air that moves across the skin; one example is cooling off by sitting under a fan. Radiation is heat transfer through infrared rays. Radiation is a transfer of heat with no contact. One example is when someone is exposed to the sun for an extended period. Evaporation is the loss of heat through the conversion of water to gas, such as the evaporation of sweat.

During the chill phase, a patient with a fever experiences severe shivering. Which process explains the patient's current symptoms? a. Pyrogens stimulated the hypothalamus to decrease the core temperature set point. b. Cytokine levels fall in response to the introduction of a pyrogen. c. Chills stop as the body generates heat through severe shivering. d. Cytokines stimulated the hypothalamus to increase the core temperature set point.

d. Cytokines stimulated the hypothalamus to increase the core temperature set point. The introduction of pyrogens stimulates monocytes and macrophages to release cytokines, which in turn stimulates the hypothalamus to increase the core temperature set point, resulting in generation and conservation of heat. Pyrogens do not stimulate the hypothalamus to decrease the set point. Cytokine levels do not fall at this phase. Chills do not stop at this point. Additional Learning Cautious evaluation of rising temperatures is important. However, it is also important to note that when an individual has a fever, thermoregulation is intact. Cooling the body will cause shivering and vasoconstriction and will make core temperature rise even higher.

The nurse is caring for an older adult with bacterial pneumonia and a fever of 101.5°F (40.8°C). No antipyretics have been ordered at this time. Which reason explains why fever may be tolerated in this case? a. Fever is common in older adults. b. Fever prevents the death of cerebral cells. c. Fever is usually related to excessive exertional muscle tissue catabolism. d. Fever enhances leukocyte mobility.

d. Fever enhances leukocyte mobility. Fever enhances leukocyte mobility, stimulating bactericidal and anti-tumor activity and transforming lymphocytes. Hyperthermia is related to excessive exertional muscle tissue catabolism. Hypothermia is common in older adults, who may be unable to generate or conserve heat. Therapeutic hypothermia can prevent death of cerebral cells and reduces cerebral edema. Additional Learning Benefits of a fever include: It lowers the serum iron level. It inhibits bacterial replication. It reduces energy consumption.

An older adult patient who was found wandering outside in the snow without a coat has exaggerated tendon reflexes, muscle rigidity, and is not shivering. Which action should the nurse consider? a. Cardiac monitoring until rewarming begins that will decrease cardiac irritability b. Remove clothing to prepare for radiant heating in the field c. Prepare for immediate therapeutic hypothermia d. Gentle handling

d. Gentle handling Gentle handling is essential for a patient with signs and symptoms of moderate to profound hypothermia because rough handling can trigger ventricular fibrillation. The patient should be given warm, dry clothing. Cardiac monitoring is essential because raising the core temperature may induce temperature-related cardiac irritability. Therapeutic hypothermia is not indicated. Additional Learning Aging affects the body's ability to regulate temperature due to factors such as: Older adults are at risk for hypothermia because of a decreased ability to generate or conserve heat. Older adults are also at risk for hyperthermia in hot, humid environments because they may have a decreased ability to lose heat.

The nurse is caring for a patient in severe hypothermia. Which instruction should the nurse include in the patient's plan of care? a. Apply heat packs to the patient's extremities to quickly restore circulation. b. Vigorously rub the patient's extremities to quickly restore circulation. c. Rewarm the patient quickly. d. Handle the patient gently to avoid cardiac dysrhythmias.

d. Handle the patient gently to avoid cardiac dysrhythmias. Handling the patient gently is an appropriate plan of care. Rewarming patients with severe hypothermia can cause cardiac dysrhythmias. Vigorously rubbing the extremities, applying heat packs to the extremities, and rewarming the patient quickly all increase the risk of cardiac dysrhythmias. Additional Learning Care of a patient with hypothermia includes: Transport to a well-equipped emergency facility is critical. Handle gently. Apply warm dry clothing. Avoid actions that cause cardiac dysrhythmias such as rapid warming, intubation, or stimulation. Use warm fluid infusions and warm humidified air to rewarm.

A patient with a fever is experiencing a headache. Which physiological process is causing this pain? a. Onset of the chill phase b. Stimulation of monocytes and macrophages c. Release of cytokines d. Presence of cytokines

d. Presence of cytokines Headache occurs as a result of the molecular activities of circulating pro-inflammatory cytokines. Onset of the chill phase is caused by a rise in the set point and activation of the body's warming responses. Release of cytokines and the stimulation of monocytes and macrophages both result in an increase in the core body temperature set point. Additional Learning Pro-inflammatory cytokines are released by phagocytes, fibroblasts, and endothelial cells in response to a pyrogen. Cytokines shift the set point upward, resulting in physiological responses to increase core body temperature. There are three phases to fever: Chill phase, as the body works to increase core body temperature Plateau phase, when the body maintains the new set point Defervescence phase, when cytokine levels fall and the set point returns to normal

A patient with rising core body temperature experiences muscle rigidity and tachycardia. Which information should the nurse expect to find in the patient's medical record? a. Exposure to strong bacteria that have entered the patient's bloodstream b. A recent case of severe hypothermia c. A recent overdose of cocaine d. Surgery with exposure to a volatile inhalational anesthetic gas and succinylcholine

d. Surgery with exposure to a volatile inhalational anesthetic gas and succinylcholine Malignant hyperthermia occurs when a genetically susceptible individual is exposed to a volatile inhalational anesthetic gas and succinylcholine. Bacteremia, cocaine, and severe hypothermia do not induce malignant hyperthermia. Additional Learning Uncontrolled heat production in malignant hyperthermia occurs as a result of: High demand for adenosine triphosphate (ATP). Rapid oxidative, chemical, and kinetic activity in the muscle tissue. Pathological increase in intracellular calcium.

The nurse is teaching a group of new parents about temperature regulation in the newborn. Which infant should the nurse identify as being at the greatest risk for heat stress? a. The low-birth-weight infant b. The infant who was subject to birth asphyxia c. The infant placed directly on an examination table d. The infant wrapped in a warm blanket in a warm room

d. The infant wrapped in a warm blanket in a warm room Overheating a wrapped infant in a hot room can lead to heat stress and death. Low birth weight, being placed directly on an examination table, and birth asphyxia are risks associated with hypothermia. Additional Learning Other groups at risk for heat-related illnesses include the following: Older adults Marathon runners in warm climates Football players during workouts Basic military trainees Sedentary individuals engaged in physical exertion