Updated: 12/31/2021

Approach to Overdose/Poisoning

Review Topic
  • Snapshot
    • A 30-year-old woman self-presents to the ED, reporting that she ingested an entire bottle of pills less than an hour ago. She refuses to disclose the type of pill. She has a sweet scent to her breath. She is escorted to the trauma bay, where her blood pressure is 130/80 mmHg, pulse is 90/min, respirations are 24/min, and SaO2 of 96% on room air. ECG reveals no unusual dysrhythmias. Large-bore IVs are inserted. Thiamine is provided, followed by D5 1/2 NS. The patient undergoes gastric lavage, followed by a single dose of activated charcoal. Abdominal radiograph is unremarkable. ASA/acetaminophen levels are unremarkable. The patient remains hemodynamically stable. She is admitted to the psychiatry inpatient service for further monitoring.
  • Introduction
    • Poisoning and overdose cause more deaths than firearms and motor vehicle accidents
    • Leading cause of nontraumatic cardiac arrest
    • General approach to undifferentiated overdose/poisoning patient involves trauma risk management including the following
      • resuscitation
      • screening (clinical evidence of toxidromes)
      • decrease absorption of drug
      • increase elimination of drug
    • Specific toxin search is secondary
  • Presentation
    • When to suspect overdose/poisoning
      • altered mental status/coma
      • young patient with life-threatening dysrhythmia
      • trauma patient
      • bizarre/unusual patient presentation
    • History
      • age
      • weight
      • past medical history
      • medications
      • substance and dose amount
      • time since exposure
        • determines prognosis and need for decontamination
      • route (PO, IV, IM)
      • intention (accidental,suicidal,homicidal)
  • Evaluation and Management
    • Primary survey with resuscitation
    • ADD: (Universal) Antidotes, Draw bloods, Decontamination
      • (universal) Antidotes: DON'T
        • not considered harmful, high benefit profile
          • Dextrose
            • any patient with AMS
          • Oxygen
            • intubate if apneic / unconscious
          • Naloxone
            • usually given in emergent setting given high prevalence of prescription opioid abuse in United States
          • Thiamine (before dextrose)
            • any patient with AMS
            • prevention/treatment of Wernicke's encephalopathy
      • Draw bloods
        • essential tests
          • CBC, electrolytes, BUN/Cr, glucose, INR/PTT, serum osmolality
            • calculate anion gap and plasma osmolar gap
          • ABG, SaO2
          • ASA, acetaminophen, EtOH levels
        • useful/nonessential tests
          • drug levels
          • Ca2+, Mg2+, Phos
          • protein, albumin, lactate, ketones, liver enzymes, CK
        • negative drug screens/levels do NOT rule out toxic overdose
          • specific drugs tested were not detected in specimen
      • Decontamination and elimination
        • gastrointestinal
          • prior to decontamination, secure airway to prevent aspiration
          • if ingestion is known to be within 1 hour: gastric lavagefollowed by activated charcoal
            • only for noncaustic agents (not acidic or alkaline)
          • if ingestion is known to be> 1 hour ago: activated charcoal
            • not for heavy metals (e.g., iron, lithium), alcohols, caustic agents
            • contraindicated in known small bowel obstruction/perforation
            • can be given in multiple doses due to low side effect profile
          • if ingestion includes drug packets, enteric-coated/sustained-release pills, and/or cannot be absorbed by activated charcoal: whole bowel irrigation
            • contraindicated in known SBO, perforation, GI hemorrhage
          • methods no longer used (i.e., wrong answers on USMLE)
            • syrup of ipecac
            • forced diuresis
            • cathartics
        • ocular and dermal
          • remove any accessories and irrigate with saline
        • urine alkalization
          • for aspirin, methotrexate, barbiturate, chlorpropamide, TCA overdose
          • pH > 7.5 traps weak acids in urine to increase elimination
        • hemodialysis
          • when all other routes of decontamination / elimination fail
          • for toxins with low Vd, high water solubility, low molecular weight, low protein binding
            • alcohols
            • lithium
            • phenobarbital
            • carbamazepine
            • valproate
            • methotrexate
    • Secondary survey
      • physical exam with search for toxidromes
      • AMPLE history to identify toxin
      • vitals, ECG, Foley, radiographs
    • Specific antidote
      • discussed elsewhere
    • Disposition
      • strongly consider admission due to delayed onset of many side effects
      • arrange psychiatric evaluationafterpatient is medically optimized
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Questions (2)

(M2.PH.17.4800) A 23-year-old male is brought into the emergency department by his girlfriend following an argument. The patient’s girlfriend claims that she threatened to break up with him. He then called her saying he was going to kill himself. When she arrived at the patient’s home, she found him lying on the couch with empty alcohol bottles and multiple pill containers. The patient reports he does not remember everything he took, but says he ingested many pills about four hours ago. The patient’s temperature is 99°F (37.2°C), blood pressure is 110/68 mmHg, pulse is 88/min, and respirations are 25/min with an oxygen saturation of 98% O2 on room air. An arterial blood gas (ABG) is obtained, with results shown below:

pH: 7.47
pO2: 94 mmHg
pCO2: 24 mmHg
HCO3-: 22 mEq/L

The patient is placed into observation. In the morning, the patient appears agitated. His girlfriend says he keeps grabbing his head, yelling about non-stop ringing in his ears. Labs and a repeat ABG shows:

pH: 7.30
pO2: 90 mmHg
pCO2: 22 mmHg
HCO3-: 9 mEq/L
Na+: 144 mEq/L
Cl-: 98 mEq/L
K+: 3.6 mEq/L
BUN: 18 mg/dL
Glucose: 100 mg/dL
Creatinine: 1.4 mg/dL

Which of the following is the best next step in management?

QID: 109336




Activated charcoal






IV haloperidol



IV sodium bicarbonate



M 7 C

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