Pediatric emergency medicine trisk 3085 3085
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Salicylates cause a mixed acid–base disturbance of primary respiratory
alkalosis and primary metabolic acidosis.
Drug absorption can be erratic, necessitating serial salicylate
concentrations as part of the assessment.
Patients may present with either an alkalemia or acidemia initially.
Young children and patients with chronic toxicity may be more likely to
demonstrate acidemia at initial evaluation.
Physical manifestations of salicylism include fever, tachypnea, nausea,
vomiting, lethargy, slurred speech, and seizures.
Treatment is geared toward alkalinization of the serum and urine.
Hemodialysis is indicated for patients with persistent acidemia, altered
mental status, or very elevated serum salicylate concentrations.
Current Evidence
Salicylates (most commonly aspirin) continue to be a common cause of poisoning
in children and adolescents. Salicylism is the result of acute ingestion in about
60% of cases and chronic ingestion in the remaining 40%. Clinical features of
acute versus chronic salicylate intoxication often require a different management
approach, depending on the manner of intoxication.
Several factors work in concert to make chronic salicylate intoxication so
common. The primary factor is aspirin’s elimination pattern. As serum salicylate
concentrations increase, the ability of the liver to metabolize the drug diminishes
until predictable, first-order elimination kinetics are replaced by unpredictable,
dose-dependent, zero-order elimination. Thereafter, increments in dose are
associated with disproportionate increases in serum salicylate concentration.
Also, much of aspirin elimination is through urinary excretion of unchanged drug.
Therefore, in the face of dehydration and decreased glomerular filtration, drug
clearance is impaired further. Finally, because aspirin is often prescribed for
illnesses that may be associated with hepatic dysfunction, reduced
biotransformation initiates the spiraling increase in serum concentration.
Unfortunately, because chronic salicylism is associated with nonspecific
symptoms (e.g., fever, vomiting, tachypnea), diagnosis may be delayed until more
striking signs of intoxication appear.
The direct effects of salicylates on metabolism are multiple. Salicylates
stimulate the medullary respiratory center, which leads to tachypnea and
respiratory alkalosis—the hallmark of salicylism. Metabolic disturbances are
widespread and include CNS hypoglycemia, as well as abnormalities in lipid and
