THERMOREGULATION

THERMOREGULATION The process of maintaining core body temperature within an optimal physiological range

Thermoregulation Process that balances heat production and heat loss - Maintain relatively constant core temperature Heat produced = heat lost - Hyperthermia and hypothermia - pathophysiologic consequences to altered thermoregulation

Thermoregulation Hypothermia Normothermia Hyperthermia Hyperpyrexia Scope of Thermoregulation Ranges from Hypothermia, to Normothermia, to Hyperthermia (Source: Giddens, 2013, St. Louis, MI: Mosby) Severe Moderate Mild <30°C 30°-34°C 34°-36°C (80°F) (80°-93.2°F) (93.2°-96.8°F) >41.5°C (106.7°F) 36.5°-37.2°C (97.7°-98.96°F) >37.2°C (98.96°F)

Thermoregulation Factors Affecting Heat Production and Conservation → Metabolic activity - basal metabolic rate (BMR) → Muscle activity → Chemical thermogenesis – epinephrine release → Sympathetic stimulation – stress response and peripheral vasoconstriction → Fever

Thermoregulation Factors Affecting Heat Loss → Radiation → Conduction → Convection → Vaporization ■ Insensible water loss ■ Insensible heat loss → Vasodilation → Reduced muscle activity → Increased respirations

ANTECEDENTS REGULATION OF BODY TEMPERATURE What factors play a role in regulating body temperature? Why? What has to happen in order for thermoregulation to occur?

Regulation of Body Temperature ● Conscious Responses  Putting on clothing, turning on fan ● Thermoreceptors in Shell and Core ▪ Peripheral thermoreceptors  Skin has more receptors for cold than warmth  Skin chilled → shivering, sweating, vasoconstriction ▪ Central thermoreceptors  Located in the spinal cord, abdominal organs, and hypothalamus

Regulation of Body Temperature ● Hypothalamic Integrator controls core temp  Activates responses to Lower or raise body temperature based on information received from the thermoreceptors  sensors detect heat  cold sensors stimulated

Regulation of Body Temperature Temperature Control The hypothalamus controls body temperature and signals for mechanisms to increase heat production or facilitate heat loss. HYPOTHALMUS HYPOTHALAMUS Decreased Temperature ● Blood vessels constrict ●Sweat glands less active ●Skeletal muscles contract, causing shivering Increased Temperature ● Blood vessels dilate – causing a flushed appearance to skin ● Sweat glands become more active

Factors Affecting Body Temperature Age Diurnal variations Exercise Hormones Stress Environment - Extremes affect thermoregulation - Newborns homeothermic

PAIR SHARE Pick a Partner Discuss developmental considerations affecting thermoregulation in the following groups and provide a rationale for your answer. Infants Young children Older adults

Risk Factors for Alterations in Thermoregulation ● Populations at Risk - Infants and young children - Older adults - People living in very cold or very hot climates - Low socioeconomic status - Homeless ● Individual Risk Factors - Impaired cognition - Underlying health conditions - Genetics - Recreational and occupational exposures

Alterations Pyrexia - Body temperature above usual range - Hyperpyrexia - Febrile - Afebrile Hypothermia - Excessive heat loss - Inadequate heat production to counteract loss - Impaired hypthalamic thermoregulation

Physical Assessment Measuring body temperature Body temperature measured in degrees on two scales - Celsius (centigrade) - Farenheit - Conversion formulas: ■ From °F to °C (Farenheit temperature – 32) x 5/9 ■ From °C to °F (Celsius temperature x 9/5) + 32

Physical Assessment, continued Sites for measurement - Oral - Rectal - Axilla - Tympanic membrane - Forehead Advantages and disadvantages of sites

Physical Assessment, continued Types of thermometers - Mercury in glass → no longer used - Electronic thermometer → fast and sanitary - Basal thermometer → used for fertility - Hyperthermia thermometer → 81 - 108° - Chemical disposable thermometers - Infrared thermometers Developmental considerations

Assessment Comprehensive History - Biographical information - Health history - Family history (malignant hyperthermia) - Recent illnesses or injuries - Environmental exposures

Assessment Physical and Physiological - Alterations in body temperature - Hyperthermia - Hypothermia Diagnostic Tests - Complete blood count (CBC) with differential - Imaging studies → for suspected head trauma

Interventions Maintain thermoregulatory mechanisms by reducing risk factors: - Environmental Control and Shelter ▪ Elderly and young infants need warmer environment ▪ Infants and children should wear hats ▪ Maintain optimal temperature in home - Adequate Hydration - Physical activity

PAIR SHARE Pick a Partner 1. Take your partner’s temperature and record it. 2. Convert °F to °C and back. 3. One student march in place for 5 minutes, and the other student sits quietly. 4. Retake temperatures and compare results. - Who has the highest temperature? - Connect exercise, increase in temperature, and risk for elderly in both hot and cold environment