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Hypothermia (Pathophysiology (In young, often due to extreme environmental…
Hypothermia
Pathophysiology
In young, often due to extreme environmental
exposure (walking, cold water immersion) or alcohol/drugs
In elderly, often multifactorial
As core temp reduces, biological enzymes caese to work
and cerebral and cardiovascular function decline
Shivering is a good sign (not that severe)
Diagnosis
Examination
Resp exam
Reduced RR and depth
Neuro exam
Reduced GCS, increased tone,
hyporeflexia
Cardio exam
Cool peripheries,
irregular/absent peripheral pulse
History
PMH
Known endocrine disorders,
metabolic disorders
DH
Meds, allergies
PC/HPC
Collateral hx: environmental exposure,
shivering, confusion, coma, ataxia
SH
Living arragements, social support, occupation,
smoking, alcohol, drugs
Examination
Bedside
Obs (low BP; bradycardia; low temp via tympanic/rectal/oesophageal)
ECG - arrhythmias (bradycardia, J waves, AF)
Bloods
FBC, CRP, U+E, LFTs,
TFTs, clotting (DIC), toxicology screen
Blood cultures
Glucose, ABG
Amylase, troponins
Imaging
CXR - any pneumonia/LVF
CT head (if indicated)
Aetiology/
precipitants
Secondary
Disrupted temp
regulation
Metabolic
Malnutrition
Trauma
Burns
CNS trauma
Endocrine
Hypothyroidism
Hypoadremalism
Vascular
Stroke
Infection
Sepsis
Denegerative
Autonomic neuropathy
Primary
Environmental exposure
Clinical
presentation
<32 degrees
Reduced conciousness
Coma
32-35 degrees
Agitation
Confusion
Amnesia
Ataxia
Dysarthria
Management
Initial (ABCDE)
Definitive
Rewarming
Active rewarming
Water bath 41 degrees (not if patient acutely unwell)
Hot air blankets
Core rewarming
Indication: severe hypothermia; cardiac arrest
MOA: heated humidified O2; warm IV fluids; peritoneal lavage 45 degrees; extracorporeal rewarming with cardiopulmonary bypass
Passive rewarming
Indication: mild cases (>32 degrees)
MOA: warm blankets, polyethylene sheets; aim 0.5-2 degrees/hr
SEs: shock if too quick (peripheral vasodilatation)
Conservative
Warm room (>21 degrees)
Gentle handling (avoid triggering VT)
Warmed humidified O2
Monitoring
Definition
Core (rectal/tympanic)
temp <35 degrees
Risk factors
Age (infants/elderly)
Complications
Rapid rewarming
Can cause hypotension (peripheral vasodilatation)
and pulmonary/cerebral oedema