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16 Cards in this Set
- Front
- Back
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Infant Homeotherms or Poikilotherms |
Homeotherms - maintain stable core temp during changes in ambient temperature. |
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Why do infants have limited thermal range |
Small size Increased surface area to volume ratio Increased Thermal conductance |
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Heat loss two stages |
1. transfer of heat from body to core to skin surface- INTERNAL TEMP GRADIENT 2. Dissipation of heat from skin surface to the environment- EXTERNAL TEMP GRADIENT. |
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Heat Loss types- Conduction |
Cutaneous blood flow Thickness of the simulation- subcutaneous tissue |
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Convection |
Air Temperature, Air velocity, and volume of air flow |
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Radiation |
MAJOR SOURCE OF HEAT LOSS - large surface area to volume ratio= great heat loss temperature gradient between skin surface and surrounding objects is between the body temp and the ambient temp. |
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Evaporation |
Relative humidity Minute Ventilation |
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Heat production |
Voluntary muscle activity involuntary muscle activity Non-shivering thermogenesis - Major component in the newborn |
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Non-shivering Thermogenesis |
Cold stress precipitates norepi release Brown Fat metabolism - highly specialized tissue w/ rich vascular supply and sympathetic system innervation heat produced byproduct of fatty acid metabolism |
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Thermoregulatory system |
Negative feedback system Principal site - hypothalamus |
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Thermal rergulation |
Afferent - detect ambient temp. travels to spinothalamic tract int the anterior spinal cord Central regulation by hypothalamus- controls set point Efferent - increased metabolic heat production, decreased environmental heat loss, and increased heat loss. |
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Increased metabolic heat production how |
Shivering Nonshivering thermogenesis |
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Decreased environmental heat loss |
active vasoconstriction - FIRST and MOST CONSISTENT RESPONSE, reduction in heat loss is 25%. Behavioral responses - quantitatively - the most important |
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Hypothermia effects |
Decrease MAC of inhalation agent increase tissue solubility of inhalation agent Decreases requirements of NDNMB's and prolongs duration In hypothermic pt, an increased amount of agent will be delivered to tissues to meet a decreased anesthetic requirement |
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Prevention of Hypothermia |
Warm operating room- decrease radiant loss, neonates and infants rooms should be 80-85 degrees* radiant heat lamps, warming mattress, warm IV fluids, heated/humidified gases, warm blankets, and wrap head in plastic |
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Temperature monitoring sites |
Core - tympanic membrane, nasopharyngeal, esophageal, and pulmonary artery Peripheral - skin, axillary, rectal |
