With respect to heat stroke:
a) Outline the pathophysiology. (20% marks)
b) List the factors that affect prognosis. (10% marks)
c) List the expected changes on routine investigations in the presence of heat stroke. (20% marks)
d) Outline the management of a patient with heat stroke. (50% marks)
a)
Uncoupling of oxidative phosphorylation
Failure of enzyme systems
Membrane permeability
increased Na leak into cells
ADP depleted
Sweat gland damage from heat
b)
Prognosis depends on core temp, duration of hyperthermia and presence of comorbidities.
c)
Haemoconcentration (dehydration), haemolysis
Hypernatremia
LFT derangements (cholestatic, early sign),
Renal impairment,
DIC often delayed onset and a/w worse prognosis
CK rise (exertional type),
Lactate rise.
During treatment: CXR pulmonary oedema (centralise fluid, ALI), low PO4, Ca, glucose,
d)
ABC (Airway protection if GCS low etc. ) & control of seizures if present
Remove from offending environment,
Rapid cooling to 39 C (duration of hyperthermia major determinant of outcome): remove clothing, sponge cold water, ice, fans, cooling blankets, cold intravenous fluids gastic lavage with cold solutions, immersion (young and military), cold dialysis, etc. Monitor core temp closely
Volume and electrolyte resuscitation and close monitoring
ABG,
Eectrolytes. NB Risk of cerebral oedema
CVC
Additional comments:
In general there was a knowledge deficit relating to the pathophysiology of heat stroke. Some candidates failed to address cooling and control of temperature in the management of heat stroke and did not recognise the need for initial rapid cooling and/ or the need for careful temperature monitoring.
The
a) Pathophysiology of heat stroke:
b) Factors that affect prognosis of heat stroke:
c) List the expected changes on routine investigations in the presence of heat stroke.
d) Outline the management of a patient with heat stroke.
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