Heat stroke

Question 1

Discuss heat exhaustion

Answer 1

Clinical syndrome characterized by volume depletion that occurs under condition of heat stress

Two types are classically described

• water depletion
• salt depletion

Water depletion results from inadequate fluid replacement in individuals working in a hot environment and incapacitated individuals without access to water – if untreated will progress to heat stroke

Salt depletion takes longer to develop
occurs when large volumes of thermal sweat are replaced with water with too little salt

Question 2

Disucss clinical features of heat exhuastion

Answer 2

Variable symptoms

• weakness
• fatigue
• frontal headache
• impaired judgment
• vertigo
• nasuea and vomiting
• muscle cramps

Core temperature is below 40 degrees or normal and nil CNS symptoms

Question 3

Discuss IX of heat exhusation

Answer 3

Manly labs

• U&E —> characterised by hyponatraemia, hypochloremia and low urinary sodium and chloride
• CK eleavtion
• Transaminiitis

Question 4

Discuss management of heat exhaustion

Answer 4

Supportive and IV fluids for replacement of electrolyte deficit

If young and not comorbid should be able to be managed at home post initial fluids and ix
if older with comorbidities should be admitted for observation

Question 5

Discuss heatstroke

Answer 5

In previous forms of heat illness although body temp rises thermoregulatory mechanisms remain intact

Heatstroke is a catastrphic life threatening emergency occurs when these mechansism fail leading to elevation in body temp to extreme measures >40.5 producing multisystemi tissue dmaage and organ dysfunction. Classic triad is of neurological dysfunction, T >41 and dry skin

Neurological dysfunction is the hallmark of heatstroke and cerebral oedema is common
-Peteichae in teh walls of the third and fourth ventricles and makred cerebella purkinje cell damage.

CVS damage

Function hypovolemia is avoided by vasoconstriction of the splanchnic and renal vasculature – the resulint splanhic and renal constriction causes ischaemia and leads to nausea and vomiting.

Hepatic damage is consistent feature fo heatstroke and its absence should cast doubt in the diagnosis

Question 6

Discuss clinical features of heatstroke

Answer 6

Sudden onset 
CNS dysfunction (coma, seizure delirium) 
Hepatic injury 
Renal injury 
Shock -- vasodilation 
Hyponatreamia

Question 7

Discuss DDX of heatstroke

Answer 7

CNS haemorrhage 
Tox 
Seizures 
Malignant hyperthermia 
Neuroleptic malignant syndrome 
serotonin syndrome 
Thyroid storm 
High fever sepsis 
Encephalitis

Question 8

Discuss management of heat stroke

Answer 8

Immersion ice bath – 0.2 degree/min

Evaporative cooling 0.1 degree/min

• strip patient of clothes
• tepid water is sprayed while fans blow air continously bon the body

Ice packs to axillae and groin
Cooling blanket
Peritoneal, rectal, gastric lavage,
ECMO

MANAGEMENT of complications

• rhabdo
• Acute heaptic failure
• seizures
• aspiration pneumonia and ARDS
• stress induced cardiomyopathy and arrhythima
• DIC
• hypoglycaemia
• hyponatraemia

A: likely need intubation 
B: as per ARDS net
C: fluid resus +- inotropes id need 
d) benzo for agitation 
E: electrolyte and glucose management 
F: aiming for urine output of 2ml/kg