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barry thermoreg
thermoregulation ppt
Question | Answer |
---|---|
What is the goal of thermoregulation? | Maintenance of stable core temperature |
Vasodialation, sweating, pilorelaxation,and stretching are a response to what? | Hot temperature |
Vasoconstriction, shivering, piloerection and curling up are a response to what? | Cold Temperature |
Heat production can increase 500% with what mechanism? | Shivering Thermogenesis |
How is non shivering thermogenesis regulated? | The SNS- it targets the BAT (brown adipose tissue) and skeletal muscle |
What is that primary thermogenic tissue in adults? | Skeletal tissues |
what is that primary thermogenic tissue in children? | BAT (brown adipose tissue) |
what are the mechanisms of heat loss? | Radidation 60%, Evaporation 20%, Convection 15%, and Conduction 5% |
What type of heat is lost by photons and without physical contact with an object? | Radiation |
How is evaporation heat loss prevented? | Humidification, covering exposed skin, and using warm preps |
In the evaporation mechanism, where is at least half of the heat lost? | Respiratory process |
Which mechanism is heat lost through direct contact with cooler objects? | Conduction |
How do you minimize conduction heat loss? | Since it's direct heat loss, put things under the pt to protect from cold OR table.(MB slide also says increase ambient temperature, forced warm air, warm solutions) |
Relating to convection which has a higer specific heat water or air? | Water: therefore warm fluids would act faster than warm air on a pt |
Afferent tempreture sensors relate to which system Central or Peripheral? | Peripheral sensors |
What is the terminal organ for cold sensations? Where is it located? | Krauses end bulb : Encapsulated receptor located in connective tissue. Range of stimulation is 15 - 25 degrees Celcius. Anything below these temps are active pain receptors |
What is the primary terminal organ for warm sensation, and where is it located? | Ruffinis corpuscle: encapsulated receptor located in the subcutaneous tissue. range of stimulation 25-45 degrees celcius |
_______ sensations are transmitted to the spinal cord by mylinated A delta nerve fibers. | Cold |
_______sensations are transmistted to the spinal cord by unmylinated C nerve fibers. | Warm |
Where do the earliest warning signs of external temp changes come from? | Perpheral temperature sensors |
When do central recpetors take over the body temperature regulation? | Once the skin reaches maximum variability. |
Efferent system has two primary pathways, what are they? | Neurologic and endocrine |
____ regulates cutaneous blood flow and nonshivering thermogenesis through adrenergic efferents adn diaphoresis through cholinergic efferents | SNS |
Skeletal muscle shivering is stimulated by direct motor response initiated by what? | Posterior hypothalamus |
What is the most important mechanism for transfering heat from the core to the periphery? | Cutaneouos vasodialation |
Heat transfer from blood to tissues is what mechanism? | convection |
In hyperthermia diaphoresis is the major mechanism for which heat loss? | evaporation |
____causes and increase of cardiac mortality, post-op infection, and an increase in recovery time and hospital lenght of stay. | hypothermia |
During hypothermia what happens to the respiratory system? | Initally it increases and then decreases |
A body temp of 32-33 degrees celcius would lead to what? | the body not being able to counteract heat loss |
A body temp of 22-24 degress celcius would lead to what ? | the body become poikilothermic |
A body temp of >33 degrees C would lead to what? | increased HR, BP, and CO |
A body temp of <31 degress C would lead to what? | atrial and ventricular irritability |
A body temp of <30 degrees C would lead to what? | sinus bradicardia and v-fib very likely |
A body temp of 21 - 24 degress C would lead to what? | risk of v-fib very high |
A body temp of < 20 degrees C would lead to what? | ASYSTOLE :( |
Cerebral blood flow and O2 consumption decrease what percentage for each degree C drop? | 7% |
MAC decreases what percentage for each degrees C drop? | 7% |
During hypothermia what happens to uring output? | It increases |
Maximum shivering happens at what temperatures? | Between 33-35 degrees C |
What happens to the the hematologic function during hypothermia? | increases HCT d/t rise in plasma volume and loss of fluid with diuresis, hyperglycemia, and impaired coagulation d/t thrombocytopenia |
What are contributors to intra-operative hypothermia. | sedative-hypnotics, opioids, volatile agents, and environment(air temp and cold table etc.) |
Who loses more heat? infants or children | infants, they can lose up to 4 times more heat than adults |
Why do infants lose more heat than adults? | they have a thin sub cutaneous layer of insulation and also due to large ventilatory minute volume |
True or False: Aging decreases the ability to compensate for heat loss. | True if >60 the metabolism decreases to less than 1/2 |
What is the best temperature that is not a core temperature measurment? | Tympanic- it is the closest to core temp d/t location being close to the hypothalmus. |
How long does it take to get a true axillary temp? | 10 -15 min for the axillary artery to equilibrate |
What is the best way to monitor core temp? | PA catheter, mixed venous blood, but core temp can be effected by CT surgery |
What are active warming methods we utilize? | Warm blankets, radiant warmness, forced air warmers (bair huggers etc.) <---most effective of these three |
What are active warming methods for the core that we can utilize? | heated humidifiers, gastric lavage, peritoneal irrigation, fluid warmers (can heat to 42 degrees C with out causing hemolysis) |
What are passive warming methods we can utilize? | ambient temperature, insulation foam under bony prominences (insulation) and HME's |