Ch 128- Hypothermia and Frost Bite Flashcards
(24 cards)
Define Hypothermia
core temperature <35 degrees C
List 5 risk factors for the development of accidental hypothermia
- exposure to cold environment
- poor health
- old age
- Drug ingestion
- Inadequate nutrition
List 5 mechanisms of heat loss
- Radiation (most profound mechanism of heat loss at rest)
- Conduction (increases when wet)
- Convection (works with conduction to increase heatloss by 25% in the wet patient)
- Respiration
- Evaporation
List 5 physiologic responses to cold
- Shivering
- increased muscle tone (pre shivering)
- Vasoconstriction
- Non-shivering basal thermogenesis
- Endocrinologic thermogenesis
Describe 3 CV manifestations of hypothermia
- Tachycardia
- acute response - Bradycardia
- HR decreases with every drop in core body temp - Osborne J waves on ECG
- typically appear when core body temp <32 - Prolonged intervals (PR, QRS; QTc)
- Afib
- VFIB/ Asystole
- usually when core body temp <25 degrees
What is the mechanism of bradycardia in hypothermia
occurs as a result of decreased spontaneous depolarization of the pacemaker cells
Define mild, moderate and severe hypothermia
**rectal or esophageal temp
Mild: 35-32
Moderate: 32-29
Severe 28-22
Profound <20
Define mild hypothermia.
Describe the physiologic changes that occur in mild hypothermia
Core temp: 35-32 degrees
CNS:
-alert
-shivering
-dysarthria
-ataxia
-impaired judgement
CVS:
- tachycardia + HTN
Resp:
- tachypnea
-bronchorrhea
GU:
- cold diuresis
Describe the physiologic changes that occur in moderate hypothermia
32-29 degrees
CNS:
- non-shovering
-dLOC
-delerium
-paradoxical undressing
-Mydriasis (dilated pupils)
CVS:
-bradycardia
-AFIB
-hypotension
Resp:
-hypoventilation
Metabolic:
- insulin ineffective
GU:
-cold diuresis
Define severe hypothermia. Describe the physiologic changes that occur in severe hypothermia
core temp 28-22 degrees
CNS:
- unconscious with pulse
-coma
-fixed dilated pupils
-areflexia
CVS:
-high risk for VFIB
-heart block
-cardiogenic shock
Resp:
-agonal resps
-pulmonary edema
GU:
-oliguria
Metabolic:
- major acid base disturbances
List 10 factors that predispose hypothermia
- Decreased heat production
-Hypopituitarism
-hypothyroidism (myxoedema coma)
-DM
-Hypoglycemia
-Malnutrition
-extreme exertion
-young and old age
-impaired shivering
-inactivity - Increased heat loss
-environmental
-immersion
-induced vasodilation
-pharmacologic
-toxicologic (ethanol)
-burns
-psoriasis
-iatrogenic
-heatstroke treatment - Impaired thermoregulation
-neuropathy
-neurogenic shock (acute spinal cord transection)
-DM
-central neurologic failure
-Stroke
-toxicologic
-metabolic
-SAH
-hypothalamus dysfunction
-parkinsons
-anorexia
neoplasm
-MS
Why are neonates at higher risk of hypothermia
- large surface area-to-mass ration
- less subcutaneous tissue
- inefficient shivering
- Lack behavioural defense mechanisms
List 3 causes of hypothermia in neonates
- Emergent delivery
- Sepsis (usually > 72h after delivery)
- NAT (Shaken baby syndrome)
Describe the treatment for mild hypothermia
exposure related- passive external rewarming
Describe the treatment for moderate hypothermia
active rewarming
external- warm blankets, environmental heat
warm fluids
Describe the treatment for severe hypothermia
active internal and external rewarming
warm blankets
warmed air
warm fluids
-PIV
-CL
-Foley
-Gastric lavage
-thoracic lavage via bilateral chest tubes
+/- ECMO
List 10 secondary causes of hypothermia
1.Obvious trigger
-cold exposure
-transfusion
-dialysis
-surgery
- Distributive shock
-sepsis
-pancreatitis - Metabolic
-DKA
-hypothyroid
-hypoglycemia
-adrenal. insufficiency
-thiamine deficiency
-malnutrition, anorexia nervosa - CNS
-spinal cord injury
-parkinsons
-MS
-thalamic injury (stroke) - Toxocologic
-ethanol
-TCAs
-sympatholytics (BB, alpha blocker)
-CO
-lithium toxicity
-central alpha agonsits (clonidine)
List 3 modalities for core temperature measurement
1 esophageal
2. bladder
3. rectal
What investigations would you include in the work up of a hypothermic patient
blood glucose
CBC + electrolytes
Coags + fibrinogen
lactate
VBG/ABG
cortisol
TSH/T4
CK/Myoglobin
toxicologic (ethanol)
what modifications are made to standard ACLS in hypothermic arrest
- Defibrillation
-less effective in severe hypothermia (<24 degrees)
-limit to 3 shocks and then defer shocks until core temp >30 - Medications
-cardiac medications can cause VT
-defer ACLS medications until core temp >30 then consider doubling dose interval until normothermia achieved (ie epi q 6-10min)
List 5 potential complications of hypothermia
- VT/VF/Asystole
- Pulmonary edema
- Rebound hyperkalemia
- rebound hypoglycemia
- coagulopathy 9increased bleeding time with normal coag levels)
- DIC (Less common)
What are the most common mechanisms of accidental hypothermia
convection heat loss to cold air and conductive heat loss to water
what is the ideal acid base goal in hypothermia
uncorrected
pH 7.4
PaCO2 40
