HypothermiaHyperthermia

Dr. Stella YiuStaff Emergency Physician

S Yiu, 2012

Hypothermia: LMCC wants you to

• List causes• List illnesses that precipitate

hypothermia• Conduct neurological, CVS and resp

assessment• List and monitor investigations • Manage a hypothermic patient by

contrasting different warming methods

NORMAL TEMPERATURE: 36.5 – 37.5 CELSIUS

Causes

1.Decreased heat production

2.Increased heat loss

3.Impaired thermoregulation

1. Decreased heat production

Not enough fuel (poor nutrition, hypoglycemia)

Engine slower (hypothyroid, hypopituitarism, adrenal insufficiency)

Engine unable to produce heat (age, impaired shivering)

Photo credit: RaGardner4 and Pedro J Perrieira, , flickr creative commons

2. Increased heat loss

Immersion/exposure

2. Increased heat loss

• Vasodilation: drugs, alcohol, sepsis, toxins

2. Increased heat loss

• Skin disorders (burn, dermatitis)

• Iatrogenic (trauma bay, 3 L cold NS)

3. Impaired thermoregulation

CentralMetabolic (Cirrhosis, uremia), drugs (barbituates, TCAs), CNS (stroke, trauma, MS, Parkinson)

PeripheralSpinal cord transection,

neuropathy, DM

Physiological effects

Pacemaker cells slllllooooow

Cardiovascular: Bradycarida, arrhythmia, VF, asytole (<28)

Neurologic: depression, activity abnormal less than 33,

Examination

35-32 – Mild

Physiological adjustment

32-29– Mod

CNS: Ataxia ConfusionCVS: Brady, Afib

< 29: Severe

CNS: Coma, fixed pupilsCVS: VF, asystole

Investigations

Temp: esophageal

Lytes (HyperK)

Coag profile (DIC)

EKG

Osborn J waves

Mild: Passive Rewarming

>30 and no CVS- Surface rewarming- Warm blankets- Removal or cold, wet clothing

Severe: Arrhythmia

VF:CPR, defib,

If first defib does not work, do not defib (continue CPR) until warmed to >30

Patient not dead until warm and dead

Severe: Active rewarming

Gently handle, no CPR on frozen chest

Airway: IntubateBreathing: Warm OxygenCirculation: Warm saline (heated to 65)

Severe: Active rewarming

InhalationIntravenous

GI lavageBladder lavage

PeritonealPleural

ECMODialysis

Invasive

NOT DEAD UNTIL WARM (>30-32) AND DEAD

Hyeprthermia

Hyperthermia: LMCC wants you to

• List causes • List illnesses that predispose to

hyperthermia• Know abnormal exams of hyperthermic

patients • Select investigations • Manage hyperthermic patient by

various cooling methods• Understand how dantrolene works

CausesEnvironment (heat stroke)

Decreased heat dissipation

ObesityDrugs (anticholinergics, serotonin syndrome, sympathomimetics)Metabolic heat

Thyroid, pheochromocytomaMalignant hyperthermiaNeuroleptic malignant syndrome

Sepsis

Examination

Heat stroke

T> 40Orthostatic BP, tachycardia, tachypneaCNS: Confusion, cerebellar, cerebral edema

NMS/MH Physical

NMS (post antipsychotic) or MH (post anesthetic)

T>40, autonomic dysfunction, lead-pipe rigidityMotor: Myoclonus, dystonia, dysphagiaCNS: confusion, agitation, coma

Hyperthemia: Clinical and lab findings

CVS: CHF, pulmonary edema, CV collpase

Liver: necrosis

Rhabdomyolysis

DIC

Cooling

Evaporative:Mist + FaceIce packs

Con: shivering, cannot attach electrodes

More aggressive cooling

Tub immersionCon: Cumbersome

GI/Peritoneal lavageCon: Invasive

Cardiac bypassCon: Invasive, not readily available

STOP COOLING WHEN TEMP < 40

Dantrolene

Muscle relaxer(interferes with coupling-excitation of skeletal muscle cells)

Only effective treatment in MH