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THE MORNING REPORT

The Best in FOAM Education

  • Jillian Leibowitz, DO

Salicylate Toxicity

Salicylate containing products

  • Methyl Salicylate

    • 1mL = 1.4g of aspirin

    • 5mL = 7g which is ~21 tablets (325mg aspirin)

  • Bismuth Subsalicylate

    • 15 mL = 130mg

    • salicylate 1mL = 8.7mg → can cause chronic or acute toxicity especially in infants

  • Excedrin: Migraine Medication OTC

    • Acetaminophen, Aspirin, caffeine

  • Alka-Seltzer: OTC hangover, heartburn, headache, stomach ache relief

    • Anhydrous citric acid, aspirin, sodium bicarb

    • 2 tablets per packet

    • 1 tablet = 325mg aspirin

    • Directions: dissolve 2 tabs in 4oz H2O

  • BENGAY

    • Muscle relief

    • Topical cream

  • Wart Removal

  • Tiger Balm

  • Teething Gel

  • Aspirin:

    • Lethal dose: 150mg/kg

    • Analgesia, antipyretic, anti-inflammatory

Pathophysiology

  • Inhibition of cyclooxygenase enzyme (COX)

  • Inhibit oxidative phosphorylation

  • Increased renal bicarbonate excretion

  • Lipolysis

  • Metabolic acidosis Activates the brainstem (medulla) → tachypnea / respiratory alkalosis

  • Two types of ingestion

    • Acute (i.e. suicide attempt)

    • Chronic (i.e. nursing home residents

Clinical Presentation

  • General

    • Tachycardia

    • Tachypnea

    • Diaphoresis

    • Hyperthermia

  • Neuro

    • Tinnitus/whooshing

    • Delirium/Agitation

    • Seizure/coma

  • Pulmonary

    • Pulmonary Edema

    • Tachypnea

  • Gastro

    • Nausea/vomiting

    • Diarrhea

  • Presentation can mimic

    • Meningitis (AMS, delirium, agitation, hyperthermia, diaphoresis)

    • Pneumonia (pulmonary edema, tachypnea, diaphoresis, hyperthermia)

    • DKA (AMS, nausea/vomiting, tachypnea)

    • Sepsis (acidosis/lactic acidosis, tachypnea, diaphoresis/hyperthermia, tachycardia, hypotension, leukocytosis/leukopenia, fevers)

  • Seizure Risk

    • pH of 7.45? 7.25? Risk of seizure and cardiac arrest

    • Risk 6-18 hours post ingestion

    • Levels >100mg/dL (severely toxic) can cause damage to basement membranes → cerebral and pulmonary edema

    • Cerebral edema → seizures

Work-up

  • Call poison control 1-800-222-1222

  • CBC, chem10, LFTs, VBG, salicylate level, APAP levels, ETOH, Utox, CXR, +/- CT head

  • FUN FACT

    • Chloride will initially be falsely elevated secondary to salicylates interfering with how chloride is measured in lab

Acid-Base

  • Respiratory Alkalosis

    • Affects the respiratory drive -> tachypnea

  • Anion Gap Metabolic Acidosis

    • Ketoacid, salicylic acid, lactic acid

    • Increases renal excretion of bicarb

    • Uncoupling oxidative phosphorylation → hyperthermia and increased lactic acid

  • Acidosis

    • Weak acid, pKA 3.5

    • Salycilate typically exists in ionized state at physiological pH

    • However, as metabolic acidosis ensues, the non-ionized form can easily cross blood brain barrier

Timing of Salicylate Levels

  • Levels peak ~6 hours post ingestion

  • Note: enteric coated tablets, peak ingestion can be delayed >12h

  • Chronic Ingestion

    • Toxicity may occur at lower doses than acute OD

    • Don’t underestimate the severity of the intoxication based off the serum level, as it has already accumulated in the brain

Management

  • Goal is to alkalinize the urine: Increasing serum pH effectively decreases toxicity

  • Non-ionized Form

    • At a lower pH, salicylate will diffuse into tissues (crossing blood brain barrier)

  • Ionized form

    • s/p alkalization

    • Won’t cross BBB

    • Excreted in urine

  • Alkalinization

    • Indications

      • Salicylate level > 40mg/dL

      • Symptomatic patients

      • Bicarb gtt

        • 1L D5W

        • Release 150cc

        • Add 3amp bicarb (150cc)

        • Run at ~200-250cc/hr

    • Note: replete potassium

    • Bicarb decreases K

    • So, you can add 40 meq Potassium Cl

    • Mechanism

      • Initially……. Body is losing bicarb into the urine

      • While bicarb is excreted into the urine, so is K and Na

      • If the patient is vomiting, that is an additional source of lost K

      • Since the body is losing K

      • Kidneys respond to decrease in K by increasing K reabsorption

      • Sending H+ out into urine (acidic urine)

      • By increasing serum K (fluid repletion with added K), it will slow the gradient for the Na K ATPase pump, halting the release of H into the urine

      • Thereby, increasing bicarb reabsorption, will cause the ionized form of salicylates into the urine and excreted out!

  • Urine Output

    • Hydrate to maintain a urine output of 2-3mL/kg/hr

  • Hemodialysis

    • Indications

    • AMS

    • Noncardiogenic pulmonary edema

    • Salicylate level:

      • >100mg/dL

      • >90mg/dL w/ renal dysfunction or despite fluid resuscitation

      • >60mg/dL chronic (nursing home patients)

      • pH <7.2 despite bicarb

Let’s review some facts

  • Salicylate Toxicity

    • Found in other medications besides aspirin

  • Toxicity

    • Acute ingestion vs. Chronic

  • Metabolic Acidosis

    • Secondary uncoupling oxidative phosphorylation

    • Excretion of bicarb in urine

  • Respiratory alkalosis

    • affects medulla -> tachypnea/hyperventilation

  • Alkalinize the urine

    • Sodium bicarb drip

  • Hemodialysis

    • Acute toxicity: > 90mg/dL

    • Chronic Toxicity: > 60mg/dL

References

  • Swaminathan A. Salicylate Toxicity. REBEL EM - Emergency Medicine Blog. Published May 17, 2018. Accessed December 7, 2023. https://rebelem.com/salicylate-toxicity/

  • Farkas J. Salicylate intoxication. EMCrit Project. Published October 1, 2021. Accessed December 7, 2023. https://emcrit.org/ibcc/salicylates/#top

  • Garner H, Long B, Santos C. EM@3AM: Salicylate Overdose. emDOCs.net - Emergency Medicine Education. Published June 20, 2020. Accessed December 7, 2023. http://www.emdocs.net/em3am-salicylate-overdose/

  • Kolowich S. Tox Cards: Treatment for Salicylate Poisoning. emDOCs.net - Emergency Medicine Education. Published January 31, 2017. Accessed December 7, 2023. http://www.emdocs.net/9997-2/

Jillian Leibowitz, DO


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