Aspirin / Salicylate Poisoning

 Aspirin / Salicylate Poisoning

One standard Aspirin tablet contains 300 mg of Acetyl salicylic acid

Ingestion of 150 mg/kg body weight produces mild toxicity.

Ingestion of 500 mg/kg body weight produces severe toxicity and fatal poisoning.

Ingestion of salicylate ointment from the skin can also produce toxicity.

Clinical features of Salicylate poisoning:

Tinnitus

Hyperventilation

Vomiting

Deafness

Sweating

Vasodilatation

Dehydration

Hypokalemia

In severe poisoning

Coma

Convulsions

Confusion

Children usually develop :

Hyperpyrexia and

Hypoglycemia

Rarer features include :

Non cardiogenic pulmonary oedema

Renal failure and 

Cerebral oedema

Metabolic and Acid Base features :

These include mixed Metabolic acidosis and Respiratory Alkalosis

But respiratory features predominate.

In a few childreand and adults , acidosis predominates and is often associated with  confusion or coma.

Management

Gastric lavage if the adult had ingested more than 4.5 Gm of Acetyl salisylic acid ( 15 tablets ) in the last 1 hour.

If the adult has ingested more than 4.5 Gm of Acetyl salicylic acid, 50 Grams of harcoal should be put in the stomach via the NG tube to reduce the absorption of Acteyl salicylic acid and to increase its elimination.

In children , if they have ingested more than 2 Grams , 25 Grams of charcoal should be put into the stomach.

Plasma salicylate concentration should be measured and repeated aftera few hours again as well.

This is because salicylate levels may increase due to continuing absorption.

In case of signs of severe poisoning or CNS Features , Plasma glucose levels, Urea and Electrolytes and Arterial Blood Gas levels should also be checked.

Mild poisoning :

Childern with plasma salicylate of less than 350 mg /l ( 2.5 mmol/l ) and adults with plasma salicylate levels of less than 450 mg /l ( 3.3mmol/l )  only need increase oral fluids to treat raised salicylate levels.

Moderate poisoning:

Children with salicylate levels of more than 350 mg/l and adults with salicylate levels of more than 450 mg/l will need iv fluids for correction of dehydration and elimination of salicylate.

Measure plasma salicylate levels and measure after a few hours again if symptoms recur as salicylate absorption may be ongoing.

Sodium bicarbonate 1.26 % ( 500 ml /hour , 3 hourly ) can correct metabolic acidosis and increase the elimination of salicylate as well as it alkanizes the urine and is superior to massive diuresis in elimination of salicylates.

Urinary pH should be more than 7.5 ( ideally 8.0 – 8.5 )

Repeated doses of Charcoal should be given.

Check Urea & Electrolytes, ABGs and serum potassium levels.

Repeat salicylate levels as needed.

Get urgent specialist  advice.

Consider urgent referral for Haemodialysis.

Salicylate Levels of more than 700 mg/L or 5.1 mmol/litre , CNS features are suggestive of severe toxicity and warrant seeking of urgent specialist advice and Haemodialysis.

Correct acidosis and give repeated charcoal by N/G tube.

IPPV may help in extreme hyperventilation with paralysis and and in life threatening poisoning with Coma

Haemodialysis removes salicylates and corrects electrolyte Imbalances.

Give additional glucose since brain glucose maybe low despite normal blood glucose concentrations.

In life threatening  poisoning with coma and extreme hyperventilation paralysis , IPPV may help while haemodialysis removes salicylates and corrects the electrolyte disturbances.