About 1% of those with an acute overdose die, while chronic overdoses may have severe outcomes. Older people are at higher risks of toxicity for any given dose. Signs and symptoms
Salicylate toxicity has potentially serious consequences, sometimes leading to significant morbidity and death. Patients with mild intoxication frequently have nausea and vomiting, abdominal pain, lethargy, ringing in the ears, and dizziness. More significant signs and symptoms occur in more severe poisonings and include high body temperature, fast breathing rate, respiratory alkalosis, metabolic acidosis, low blood potassium, low blood glucose, hallucinations, confusion, seizure, cerebral edema, and coma. The most common cause of death following an aspirin overdose is cardiopulmonary arrest usually due to pulmonary edema.High doses of salicylate can cause salicylate-induced tinnitus. Severity
The severity of toxicity depends on the amount of aspirin taken. Pathophysiology
High levels of salicylates stimulate peripheral chemoreceptors and the central respiratory centers in the medulla causing increased ventilation and a respiratory alkalosis. The increased pH secondary to hyperventilation with respiratory alkalosis causes an increase in lipolysis and ketogenesis which causes the production of lactate and organic keto-acids (such as beta-hydroxybutyrate). The accumulation of these organic acids can cause an acidosis with an increased anion-gap as well as a decreased buffering capacity of the body. Salicylate toxicity also causes an uncoupling of oxidative phosphorylation and a decrease in citric acid cycle activity in the mitochondria. This decrease in aerobic production of adenosine triphosphate (ATP) is accompanied by an increase in anaerobic production of ATP through glycolysis which leads to glycogen depletion and hypoglycemia.
Initial treatment of an overdose involves resuscitation measures such as maintaining an adequate airway and adequate circulation followed by gastric decontamination by administering activated charcoal, which adsorbs the salicylate in the gastrointestinal tract. Stomach pumping is no longer routinely used in the treatment of poisonings, but is sometimes considered if the patient has ingested a potentially lethal amount less than one hour before presentation. Inducing vomiting with syrup of ipecac is not recommended. Repeated doses of activated charcoal have been proposed to be beneficial in cases of salicylate poisoning, especially in ingestion of enteric coated and extended release salicylic acid formulations which are able to remain in the gastrointestinal (GI) tract for longer periods of time. Repeated doses of activated charcoal are also useful to re-adsorb salicylates in the GI tract that may have desorbed from the previous administration of activated charcoal. The initial dose of activated charcoal is most useful if given within 2 hours of initial ingestion. Contraindications to the use of activated charcoal include altered mental status (due to the risk of aspiration), GI bleeding (often due to salicylates) or poor gastric motility. Whole bowel irrigation using the laxative polyethylene glycol can be useful to induce the gastrointestinal elimination of salicylates, particularly if there is partial or diminished response to activated charcoal.Alkalinization of the urine and plasma, by giving a bolus of sodium bicarbonate then adding sodium bicarbonate to maintenance fluids, is an effective method to increase the clearance of salicylates from the body.