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Salicylate Poisoning, Emergency Medicine

Basics

Description

- GI: - Nausea - Vomiting - Epigastric pain - Hematemesis

- Salicylate level: - At presentation and then q2h until level begins to decline - Verify that units are correct, generally mg/dL.

- Urinalysis: - PT/PTT with significant ingestions - Ferric chloride test: - Purple if salicylate present - Positive 30 min postingestion

- Acute salicylate poisoning: - Consider with change in mental status, unexplained noncardiogenic pulmonary edema, mixed acid " “base disorder. - Methanol - Ethylene glycol - Conditions causing noncardiogenic pulmonary edema

- Indications for hemodialysis include: - CHF - Noncardiogenic pulmonary edema - CNS depression - Seizures - Unstable vital signs - Severe acid " “base disorder - Hepatic compromise - Coagulopathy - Underlying disease state compromising elimination of salicylate - Absolute salicylate level should not be used as sole criterion for deciding to dialyze without considering patients clinical status unless level is >80 " “100 mg/dL in acute ingestion.

  • Respiratory alkalosis and metabolic acidosis:Secondary to inhibition of Krebs cycle and uncoupling of oxidative phosphorylation
  • Dehydration, hyponatremia or hypernatremia, hypokalemia, hypocalcemia:Owing to increased sweating, vomiting, tachypnea
  • Noncardiogenic pulmonary edema:Because of toxic effect of salicylate on pulmonary endothelium resulting in extravasation of fluids
  • Salicylate pharmacokinetics change from first order to zero order in overdose setting; i.e., a small dosage increment results in a large increase in salicylate concentration.
  • Greater morbidity
  • Respiratory distress/altered mental status indicative of severe toxicity
  • Diagnosis of salicylate intoxication delayed because underlying disease states mask signs and symptoms; e.g., CHF
  • Children exhibit faster onset and more severe signs and symptoms than adults:Results from salicylate being distributed more quickly into target organs such as brain, kidney, and liver
  • Respiratory alkalosis (hallmark of salicylate poisoning in adults) may not occur in children.
  • Metabolic acidosis occurs more quickly in children than in adults.
  • Hypoglycemia more common than hyperglycemia
  • Ingestion of more than "a taste " ť of oil of wintergreen (98% methyl salicylate) by children <6 yr or >4 mL of oil of wintergreen by patients >6 yr warrants ED assessment.

Etiology

Sources of salicylate: ‚

  • Aspirin:Ingestion of >150 mg/kg can cause serious toxicity
  • Oil of wintergreen:Any exposure should be considered dangerous.
  • Bismuth subsalicylate
  • Salicylsalicylic acid (salsalate)

Diagnosis

Signs and Symptoms

  • GI:NauseaVomitingEpigastric painHematemesis
  • Pulmonary:TachypneaNoncardiogenic pulmonary edema
  • CNS:TinnitusDeafnessDeliriumSeizuresComa

History

  • Ask if taking aspirin or aspirin products:Many patients do not list aspirin among their regular medications, may not consider aspirin a medication.
  • Patients may not know the difference between aspirin, acetaminophen, and the OTC NSAIDs

Essential Workup

  • Salicylate level:At presentation and then q2h until level begins to declineVerify that units are correct, generally mg/dL.
  • Watch for recurrence of signs of salicylate toxicity and increasing levels even after levels have declined due to intestinal absorption of enteric-coated products and salsalate

Guidelines for Assessing Severity of Salicylate Poisoning ‚

  • Acute ingestion of:<150 mg/kg or <6.5 g of aspirin equivalent " ”considered nontoxic150 " “300 mg/kg " ”mild to moderately toxic>300 mg/kg " ”potentially lethal
  • In the chronic overdose setting:Manage patient on clinical findings and not solely on levelsClinical findings are better indication of severity than plasma salicylate levelsNo valid nomogram exists for salicylate level interpretationSalicylate levels needed to achieve anti-inflammatory effect (20 " “25 mg/dL) approach toxic levelsEnteric-coated aspirin absorbed in intestine; peak level delayed

Diagnosis Tests & Interpretation

Lab

  • Arterial blood gas (ABG):Respiratory alkalosisMetabolic acidosis
  • CBC
  • Electrolytes, BUN/creatinine, glucose:Anion-gap metabolic acidosisHypokalemiaBaseline renal function
  • Urinalysis:
  • PT/PTT with significant ingestions
  • Ferric chloride test:Purple if salicylate presentPositive 30 min postingestion
  • In the presence of salicylate, Phenistix turn brown-purple; may detect concentrations as low as 20 mg/dL

Imaging

  • Abdominal flat-plate radiograph for concretions
  • Chest radiograph for pulmonary edema

Differential Diagnosis

  • Acute salicylate poisoning:Consider with change in mental status, unexplained noncardiogenic pulmonary edema, mixed acid " “base disorder.MethanolEthylene glycolConditions causing noncardiogenic pulmonary edema
  • Chronic salicylate poisoning:Impending myocardial infarctionAlcohol withdrawalOrganic psychosesSepsisDementia

Treatment

Pre-Hospital

In suspected overdose settings, medication bottles must be brought in for review ‚

Initial Stabilization/Therapy

  • Management of airway, breathing, and circulation (ABCs)
  • Naloxone, thiamine, glucose (or Accu-Chek) for altered mental status
  • IV rehydration with 0.9% normal saline (NS) for hypotension

Ed Treatment/Procedures

  • Morbidity from chronic salicylate poisoning may be greater than from acute poisoning.
  • Aggressively manage all salicylate intoxication.

Gastric Decontamination

  • Administer activated charcoal in alert patients.
  • Whole-bowel irrigation of theoretical benefit:For concretions visible on abdominal radiographFor ingestion of sustained-release preparationIf salicylate levels continue to increase despite appropriate managementDo not use in patients who may develop altered mental status

Enhanced Elimination

  • Alkalinization:Enhances elimination of ionized salicylateIndications:AcidosisPresence of symptomsElevated salicylate levels1 or 2 ampules of sodium bicarbonate followed by IV D5W 1L with 3 ampules of sodium bicarbonate:Goal: Urine pH of 7.5 " “8 at the rate of 3 " “6 mL/kg/hAdd 20 " “40 mEq KCl per liter to avoid hypokalemiaAvoid fluid overload with CHF or CADClosely monitor serum potassium
  • Indications for hemodialysis include:CHFNoncardiogenic pulmonary edemaCNS depressionSeizuresUnstable vital signsSevere acid " “base disorderHepatic compromiseCoagulopathyUnderlying disease state compromising elimination of salicylateAbsolute salicylate level should not be used as sole criterion for deciding to dialyze without considering patients clinical status unless level is >80 " “100 mg/dL in acute ingestion.
  • Threshold to dialyze is lower in patients with chronic overdose.

Medication

  • Activated charcoal slurry: 1 " “2 g/kg up to 90 g PO
  • Dextrose: D50W 1 amp (50 mL or 25 g) (peds: D25W 2 " “4 mL/kg) IV
  • Naloxone (Narcan): 2 mg (peds: 0.1 mg/kg) IV or IM initial dose
  • Thiamine (vitamin B1): 100 mg (peds: 50 mg) IV or IM

Follow-Up

Disposition

Admission Criteria

  • Monitor patients with salicylate levels >25 mg/dL until level drops <25 mg/dL and symptoms abate.
  • Salicylate levels increasing after having trended downward to nontoxic levels:In patients who ingest sustained-release aspirin, enteric-coated aspirin, and any aspirin product with delayed absorption
  • ICU admission for altered mental status, metabolic acidosis, pulmonary edema

Discharge Criteria

Repetitive salicylate levels <25 mg/dL and resolution of symptoms ‚

Follow-Up Recommendations

  • Psychiatric referral for intentional ingestions
  • Close primary care follow-up for chronic ingestions

Pearls and Pitfalls

  • Patients need to maintain their respiratory drive to reverse acidemia, respiratory acidosis:Do not intubate prematurely.It is extremely difficult to achieve and maintain mechanical hyperventilation in these patients.
  • Salicylate poisoning may result from topical exposure to salicylate-containing lotions or creams, rectal suppositories, oral antidiarrheal preparations.
  • Salicylate levels may trend downward only to begin increasing again due to absorption of product from the intestine or from a salicylate bezoar in the gut.

Additional Reading

  • Kent ‚ K, Ganetsky ‚ M, Cohen ‚ J, et al. Non-fatal ventricular dysrhythmias associated with severe salicylate toxicity. Clin Toxicol (Phila). 2008;46:297 " “299.
  • Stolbach ‚ AI, Hoffman ‚ RS, Nelson ‚ LS. Mechanical ventilation was associated with acidemia in a case series of salicylate-poisoned patients. Acad Emerg Med. 2008;15:866 " “869.
  • West ‚ PL, Horowitz ‚ BZ. Delayed recrudescence to toxic salicylate concentrations after salsalate overdose. J Med Toxicol. 2010;6:150 " “154.

Codes

ICD9

  • 276.2 Acidosis
  • 276.3 Alkalosis
  • 965.1 Poisoning by salicylates

ICD10

  • E87.2 Acidosis
  • E87.3 Alkalosis
  • T39.011A Poisoning by aspirin, accidental (unintentional), init
  • T39.012A Poisoning by aspirin, intentional self-harm, init encntr

SNOMED

  • 7248001 Poisoning by salicylate (disorder)
  • 35528000 Metabolic acidosis due to salicylate (disorder)
  • 111378004 Respiratory alkalosis
  • 290145004 Intentional aspirin poisoning (disorder)
  • 290149005 Salicylic acid salt poisoning of undetermined intent (disorder)