Hypothermia Flashcards
Primary causes of hypothermia
Patients that have normal heat production, but have been exposed to extreme cold temperatures.
Also referred to as accidental hypothermia
What are secondary causes of hypothermia?
Severe illness, injury, or drug induced alterations in thermoregulations such as anesthesia
Moderate hypothermia is beneficial in what situation?
A moderate temperature of 28-32C (82-90F), can be protective to some organs and tissues for a period of time and is actually used as a therapeutic tool in brain injury.
A cool brain is more resistant to ischemia from low blood flow
What electrolyte disturbances do you expect to see in a hypothermic patient?
*Electrolyte disturbances: especially serum potassium levels. Will initially be low as K shifts into the cells with hypothermia, but will then increase as temperature decreases further as cells are damaged and potassium leaks into the extracellular space
Why would you expect to see coagulation disorders in a hypothermic patient?
Coagulation is impaired at low body temperatures as enzymatic activity of coagulation factors is decreased, and platelet aggregation is reduced at low body temperatures
Would cardiac output be increased or decreased in a hypothermic patient?
Decreased secondary to bradycardia and vasodilation, arrhythmias (especially ventricular fibrillation) occurs at very low temperatures
What are the respiratory sequela to hypothermia?
Decreased RR, hypoxia and shift in the oxyhemoglobin dissociation curve results in a increase affinity of oxygen to hemoglobin, and thus decrease oxygen delivery to the tissues
What organ systems are affected due to hypothermia?
- Pancreas: Decreased enzymatic activity, inflammation and increased risk of pancreatitis
- Renal: “Cold diuresis” is an inappropriate diuresis associated with hypothermia that can rapidly cause dehydration, acute tubular necrosis as a result of low blood flow
- CNS: decreased mentation, central depression and coma, secondary to decreased cerebral blood flow.
At what temperature is thermoregulation impaired?
Below 34C (94F)
Animal will no longer shiver or seek heat
- Vasocontriction which was employed to reduce heat loss, reverses to vasodilation and further heat is lost.
- Decreased metabolic rate at the cellular level means decreased heat production
- hence heat loss actually increases at 34C (94F)
- patient will get colder faster
At what temperature will all thermoregulation attempts cease?
At 31C (88F) and animal body temperature will continue to drop quickly
Patients presenting with primary hypothermia may present with a higher or lower temperature than those with a secondary hypothermia?
A much LOWER body temperature because typically there are external factors such as cold immersion that cause the patient to cool off much more rapidly .
What is the phenomenon called “Afterdrop”?
It is a decrease in core temperature secondary to rewarding efforts. This occurs when the skin is warmed and vasoconstricted tissues begin to dilate, moving cold blood from these tissues into the central vasculature.
Patient’s are very susceptible to burns, why is that?
They are vasoconstricted (moderate hypothermia) and this will cause localised warming, but blood is not shunted away, leading to burns. Hence, warming devices needs to be moved around or the patient needs to be moved frequently.
In moderate to severe hypothermia, where should external warming efforts be concentrated on?
The main body trunk, avoiding the limbs and thus avoiding rapid peripheral vasodilation, which can cause patient to have circulatory collapse.
The vasculature of the limbs should be allowed to vasodilator slowly as warming progresses, allowing the cardiovascular system to adjust to changes and prevent collapse.
What warming methods would you use for severe and profound hypothermia?
Invasive warming efforts.
Any infused solutions must not exceed 43C (109.5F) to avoid damage to the internal tissues.
Care must also be taken when infusing these warmed solutions via a central line, as the resulting temperature gradient at the heart may lead to irritability of the myocardium, and more cardiac arrhythmia.
