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28 Cards in this Set
- Front
- Back
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NORMAL THERMOREGULATION
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-tightly regulated and maintained by the ANS
-HYPOTHALAMUS - dominant thermoregulatory site |
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DEF FOR HEAT LOSS AND PRODUCTION
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-heat loss (dissipation)
-production (metabolism) |
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THREE PHASES OF PROCESSING OF THERMOREGULATORY INFORMATION
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-afferent thermal sensing
-central regulation -efferent responses |
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AFFERENT THERMAL SENSING
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-cold receptors (alpha - delta)
-heat receptors (c-fibers) |
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EFFERENT RESPONSES
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-sweating, peripheral cutaneous vasoconstriction, brown fat metabolism (NST), shivering, and vasomotion
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SHIVERING
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-increased heat production by about 300%
-(^ pt discomfort, ^ CO2 production, ^ O2 consumption by about 200%, ^ CO, HR, SVR) |
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PRIMARY HEAT PRODUCTION IN INFANTS
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-NST non shivering thermogenesis
-primarily in infants |
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RADIATION
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-mode of heat loss
-dissipating heat to cooler surroundings -ex. uncovering, exposure -50-60% heat loss under anesthesia and surgery through radiation |
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CONVECTION
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-mode of heat loss
-hospital gowns, thin sheets, cool ambient temps, air flow over exposed areas -~35% heat loss |
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CONDUCTION
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mode of heat loss
-caused by heat transfer between objects, cold supplies and equip, wet linen, drapes, cold fluids |
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EVAPORATION
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-mode of heat loss
-gas exchange, heat liberation (sweating on a hot day) incisions, long surgeries |
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REDISTRIBUTION
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-mode of heat loss
-heat from warm core to cool periphery (anesthetic gases causes vasodiation) |
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BLADDER TEMP
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-only accurate when there is urine in the bladder
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ESOPHAGEAL TEMP
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-accurate for core temp only when placed accurately
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SKIN TEMP
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may be 3-4 degrees off
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WHO IS AT RISK FOR HYPERTHERMIA?
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EVERYONE
-infants - unable to shiver, brown fat, minimal reserves, ^blood loss --> devastating -elderly- reduced autonomic function, lower metabolic activity, hypothermic --> induced hyperK+ leads to dysrhythmias, ^blood viscoscity --> PE, and DVT -burns- lost thermoregulatory mechanism -trauma- exposure, rapid fluid resuscitation -spinal cord- autonomic dysfunction, unable to regulate vasoconstriction, prone to venous stasis -ALSO - cachectic, intoxicated, drug OD, head injury, spinal/septic shock |
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VOLATILE ANESTHETICS AND HYPOTHERMIA
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-impair thermoregulatory center of the hypothalamus
-causing 40% decrease in heat production -inhibition of shivering -produce peripheral vasodilation |
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GASES ARE
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-non humidified
-non heated gases |
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FIRST HOUR OF SURGERY?
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-pt will lose75% of heat through redistributive hypothermia
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OPIOIDS
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-reduce vasoconstrictive mechanisms via sympatholytic properties
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BARBITUATES
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-cause peripheral vasdilation
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MUSCLE RELAXANTS
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-reduce muscle tone and prevent shivering thermogenesis
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REGIONAL ANESTHESIA
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-produces sympathetic blockade, muscle relaxation, sensory blockade of thermal receptors
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ADVERSE EFFECTS OF HYPOTHERMIA
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-alters action and metabolism of many drugs
-^mortality -longer recovery time -reduction in motor and cognitive function -pt discomfort -infection and delayed wound healing -thermoregulatory vasoconstriction -coagulopathy - |
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PHARMACOLOGIC EFFECTS OF HYPOTHERMIA
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-muscle relaxants- duration of action of vec is doubled with 2degree drop
-volatile anesthetics- tissue solubility increases, larger amounts of anesthetics eventually need to be expired, |
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ACTIVE WARMING
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-forced warm air (effective due to the properties of convection and radiation)
-irrigate with warm solutions -give warm iv solutions |
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NORMOTHERMIA
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36-38 DEGREE CELLCIUS
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HYPOTHERMIA
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less than 36 degree cellcius
considered present regardless of temp if pt feels cold |
