Temperature

Question 1

What is heat stroke?

Answer 1

Defined as elevated core body temp >40.5C with associated neurological compromise

Non-exertional (classic) usually occurs at the extremes of age or in those with significant medical co-morbidities who spend extended time in an area with elevated temp (ie locked in a car)

Exertional usually occurs in young fit and healthy adults doing vigorous exercise in areas of high heat

Question 2

What are the risk factors for death in heat stroke?

Answer 2

Any evidence of other end organ damage ie anuria, coma, CVS collapse, DIC

Question 3

What are the risk factors for developing heat stroke?

Answer 3

Extremes of age
Pregnancy
Decreased mobility
Morbid obesity
Significant medical co-morbidities
ETOH or illicit drug use
Dehydration
Anticholinergis, anti-diuretics, topiramate

Question 4

What are the differentials for hyperthermia?

Answer 4

Environmental
- heat stroke (exertional or not)

Infectious
- meningoencephalitis
- Severe sepsis
- Falciparum malaria
- Tetanus
- Typhoid fever

Neurologic
- Hypothalamic stroke
- Bleed
- Status epilepticus

Endocrine
- Thyroid storm
- Pheochromocytoma
- DKA

Oncologic
- Lymphoma/leukaemia

Tox
- Malignant hyperthermia
- Serotonin syndrome
- Neuroleptic malignant syndrome
- Sympathomimetics
- Anticholinergics
- Salicylate poisoning
- Alcohol/GHB withdrawal

Question 5

What is the most common heart rhythm with hypothermia <32C?

Answer 5

• Slow AF if alive
• VF if arrested

Question 6

What is the most common neurological sign in heat stroke?

Answer 6

• The cerebellum is the most vulnerable part of the brain
• Often present with ataxia
• However any neurological symptoms/signs can occur
• Often have seizures during the cooling process

Question 7

What are the differentials for hypothermia?

Answer 7

Increased heat loss
- Environment
- Induced vasodilation (drugs, alcohol, toxins, sepsis)
- Burns/trauma

Iatrogenic
- Cold infusions
- RRT/ECMO
- Emergent deliveries

Endocrine
- Hypoadrenal/pituitarism/thyroid
- Malnutrition/hypothiamine
- Hypoglycaemia

Neuromuscular
- Extremes of age
- Impaired shivering
- Inactivity
- movement disorders (ie spinal cord injuries, cerebral palsy)

CNS
- Hypothalamic disorders
- SAH, CVA
- Parkinsons
- MS
- Anorexia

Drugs
- beta blockers, CNS depressants

Others
- Sepsis, Uraemia, pancreatitis

Question 8

How do the symptoms and signs of hypothermia change with severity?

Answer 8

Question 9

What are the different severity gradings for hypothermia?

Answer 9

Temperature based
- Cold stress 35-37C
- Mild 32-35C
- Moderate 28-32
- Severe <28C

Swiss staging system
HT 1- Mild 32-35, shivering, normal mentation
HT 2- moderate 28-32, no shivering, has altered mental status
HT 3- Severe, unconscious, 24-28C
HT 4- Apparent death, 13.7-24C but possibility of revival
HT 5- Complete death, 9-13.6C

Question 10

How does ACLS change with hypothermia?

Answer 10

• Prepare for extended periods of CPR >90mins
• Early consideration for ECMO CPR
• If < 30C then up to 3 shocks for VF, but after this no shocks until >30C
• No drugs until >30C
• Between 30-35C double the dosing interval for drugs
• Do prolonged pulse checks or use Echo/doppler to assess for pulse
• Moving patients <32C may precipitate VF