An Approach to Salicylate Poisoning
A 17 year old female with no past medical history is brought in by her mother for nausea and vomiting. Her mother provides most of the history. After arriving home this evening, she called to her daughter to come down for dinner. When her daughter did not appear, she went upstairs to her room and discovered her in bed, covered in vomit, and smelling of alcohol. The mother was able to arouse the patient and brought her to the ER.
Mom adds that the patient was well this morning but knew that the daughter had fight with her boyfriend this afternoon. When interviewed alone the patient admits to taking a handful of aspirin with vodka in a suicide attempt three hours ago. She is unsure how many pills were in the bottle. She denies any other ingestions.
VS: BP 110/70, HR 106, T 37.9, RR 22, O2 98% RA.
General: Malaise but awake and oriented
Pulm: Lungs CTA, taking deep breaths
CV: Tachycardic, no murmurs or gallops
Abdomen: soft and non-tender, no rebound or guarding, no costovertebral tenderness
Psych: tearful, but cooperative
EKG: Sinus tachycardia at rate of 110, normal intervals
Labs including ASA level: Pending, CXR: pending
Generally accidental ingestions in children, intentional ingestion in adolescents/adults, or chronic overdose in unknowing elderly patients
Classic vital signs derangements: tachypnea, hyperthermia, tachycardia
Classic symptoms: nausea, vomiting, tinnitus, altered mental status or lethargy, pulmonary edema (severe cases)
Salicylate increases respiratory rate is due to the activation of the respiratory center in the medulla → respiratory alkalosis, which in turn
Stimulates renal excretion of bicarb à metabolic acidosis
Stimulates the chemoreceptor trigger zone of the medulla → Nausea/vomiting
Uncoupling of oxidative phosphorylation of the mitochondria, which leads to an increase in ketoacid and lactic acid → metabolic acidosis
Respiratory acidosis can occur due to fatigue of respiratory muscles or pulmonary edema (due to pulmonary vascular permeability)
Suspect in a patient with history of ingestion with tachycardia, tachypnea, and hyperthermia
The chemistry will show decreased bicarbonate. The ABG will show a mixed respiratory alkalosis and metabolic acidosis. Other toxicology labs are important to evaluate for co-ingestions. And, of course, a fingerstick is mandatory. Don't forget the b-hCG if the patient is a female of reproductive age.
Obtain a CXR to evaluate for pulmonary edema if patient is hypoxic.
Urinalysis (more on this below)
Check the salicylate level:
10-30 mg/dL is therapeutic
> 50 mg/dL patients will show signs of intoxication
> 100 mg/dL in acute and > 60 mg/dL in chronic intoxications are indications for HD
Supportive: IV fluids, O2
As always start with the ABCs: if altered and vomiting (AKA not protecting the airway) or patient appears to be tiring and therefore hypoventilating → intubate! But be careful.
These patients usually have metabolic acidosis so be sure to set a HIGH respiratory rate on the vent to prevent combined metabolic and respiratory acidosis → which could cause the patient to code
Activated charcoal (1 g/kg up to 50 g) if not severely altered. If they are altered, it might be necessary to intubate first.
Bicarbonate → Urine alkalization with goal urine pH > 7.5. This enhances elimination of salicylates.
Bolus: 1-2 mEq/kg (about two amps in an adult)
Maintenance: bicarbonate drip at 2 times maintenance
Coma/seizures, pulmonary edema, severe acidosis despite bicarbonate infusion, salicylate >100 mg/dL in acute intoxication or over 60 mg/dL in chronic
Call poison control
Call nephrology if plans for hemodialysis
Admit to the ICU
Wei Li, MD is a current second year resident at Stony Brook Emergency Medicine.
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Dillon EC Jr, Wilton JH, Barlow JC, Watson WA. Large surface area activated charcoal and the inhibition of aspirin absorption. Ann Emerg Med. 1989;18(5):547-552. doi:10.1016/s0196-0644(89)80841-8
Vree TB, Van Ewijk-Beneken Kolmer EW, Verwey-Van Wissen CP, Hekster YA. Effect of urinary pH on the pharmacokinetics of salicylic acid, with its glycine and glucuronide conjugates in human. Int J Clin Pharmacol Ther. 1994;32(10):550-558
Edited by Bassam Zahid