Hypo+hyperthermia Flashcards
(35 cards)
What is hypothermia?
A condition in which an organisms body temp drops below that required for normal metabolism and bodily functions.
Temperature range for mild hypothermia
32 to 35
Temperature range for moderate hypothermia?
28 to 32
What is the range of temperature for severe hypothermia?
Anything less than 28
Why is thermoregulation important?
Maintenance of body temp is important as all chemical reactions will only function adequately within a normal given temperature
What is the role of the hypothalamus?
The hypothalamus reacts to signals from the thermoreceptors throughout the body in order to trigger heat production or heat loss mechanisms
Where are the central thermoreceptors?
Hypothalamus, spinal cord, abdominal organs
What are thermoregulatory controls?
Complex hormone pathways throughout the endocrine system that stimulate or inhibit the release of hormones into the blood stream to cause vasoconstriction/vasodilation.
What are the mechanisms of heat loss?
Radiation, conduction, convection, and evaporation.
What is radiation in the context of heat loss?
Body heat is lost to nearby objects without physically touching them
What is convection in the context of heat loss?
Body heat is lost to surrounding air, which becomes warmer, rises, and is replaced with cooler air
What is evaporation in the context of heat loss?
Body heat causes perspiration which is lost from the body surface when changed from liquid to vapour
What is conduction in the context of heat loss?
Body heat is lost to nearby objects through direct physical touch
Describe shivering thermogenisis
- The body’s mechanism in response to early hypothermia
- Core body temp drops and triggers the shivering reflex, causing involuntary muscle contractions
- Muscle groups around the vital organs begin to shake in small movements in an attempt to create warmth by expending energy, which is very effective in raising body temp.
How does constriction of cutaneous blood vessels promote heat?
Works to reduce blood flow to the skin and therefore reduce heat loss.
What is the process of increasing the metabolic rate (chemical thermogenesis)?
Hypothalamus -> anterior pituitary -> TSH -> thyroid hormone excretion -> increased BMR
What is a respiratory effect of hypothermia?
Oxyhaemoglobin dissociated curve shifts to the left, impairing oxygen delivery to cells
What is a cardiac effect of hypothermia?
As the heart cools it becomes at risk of developing arrhythmias and the VF threshold is lowered
True or false: rough handling/sudden posture changes of hypothermic pts can trigger VF.
True
How does hypothermia cause conflicting acid/base imbalances?
- Initial increased respiratory drive causes respiratory alkalosis
- Na/K pump dysfunction and lactic acid production from shivering and poor perfusion causes metabolic acidosis
- Decreased respiratory drive causes respiratory acidosis
In the initial stages of hypothermia is there increased or decreased insulin production?
Increased, progressing to hypoglycaemia as reserves are depleted
Which specialty populations are at increased risk of hypothermia?
Geriatrics and neonates
What is circum-rescue collapse?
Rescue from cold stress in seemingly stable and conscious state, then to collapse soon after with symptoms from syncope to cardiac arrest
Trauma pts are considered hypothermic at what temperature?
<36.0 degrees Celcius
