Sun28November0440PM 5

A 25-year-old woman is admitted to the Emergency Department with a suspected overdose of aspirin. The patient has been vomiting and complains of tinnitus.

On examination, she is sweating profusely, clinically dehydrated, and restless. Her vital signs are: temperature 38.5°C, pulse 120 regular, blood pressure 140/85 mmHg, respiratory rate 25 breaths per minute, Glasgow coma score of 12 and oxygen saturation 95% on air. It is thought that the aspirin was ingested eight hours ago and the plasma levels have already peaked.

The biochemistry results are as follows:

pH 7.25 (7.35-7.45)

PaCO2 20 mmHg (38-42)

PaO2 102 mmHg (75-100)

BE +8 (-3 to +3)

Bicarbonate 22 mEq/L (22-28)

SpO2 96%

Glucose 13 mmol/L (3.5-5.5)

Salicylate levels 601 mg/L

Which one of the following is the most appropriate initial clinical intervention in this case?

(Please select 1 option)

Gastric lavage

Haemodialysis

Forced diuresis

Alkalinise the urine Correct

Activated charcoal

Explanation

The clinical picture of this patient is consistent with a moderate overdose of aspirin.

There is no specific antidote to ingested salicylates.

The management of a poisoning is supportive, with measures to prevent further absorption from the gastrointestinal tract and enhance excretion.

The initial treatment, especially of this patient, should include the administration of activated charcoal, and this should be repeated as bezoars may form, resulting in delayed absorption of salicylate. This should continue until salicylate levels have peaked.

Gastric lavage is useful if the ingestion is known to have occurred within one hour; the airway should be protected during the procedure. The patient should then be rehydrated and the urine alkalinised to promote urinary excretion. This is achieved by giving an infusion of 1.25% or 8.4% sodium bicarbonate. The ionisation of a weak acid, such as salicylic acid, is increased in an alkaline environment. The administration of an intravenous infusion of sodium bicarbonate aiming for a urinary pH of 7.5-8 will increase the excretion of the acid 10-fold.

A forced diuresis alone is not recommended as it can lead to severe electrolyte disturbance and pulmonary or cerebral oedema.

Severe cases of salicylate poisoning where plasma levels of salicylate are high >800 mg/L, severe metabolic acidosis, acute kidney injury, or have neurological impairment (coma, hallucinations or seizures) may require early haemodialysis.

Reference:

Dargan PI, Wallace CI, Jones AL. An evidence based flowchart to guide the management of acute salicylate (aspirin) overdose. Emerg Med J. 2002;19:206-9.

Answer Statistics

1

49%

2

3%

3

46%

4

4%

Times answered: 317