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Difficulty: HardInitial Stabilization and Triage

A 26-year-old woman is brought to the emergency department by paramedics after being found unresponsive in her apartment. Her roommate reports finding empty bottles of amitriptyline and diphenhydramine on her nightstand. En route to the hospital, the patient had a 3-minute generalized tonic-clonic seizure. Upon arrival, she is actively seizing. Vital signs are temperature 38.2°C (100.8°F), blood pressure 82/50 mm Hg, pulse 138/min, and respirations 8/min. Pulse oximetry shows 88% on room air. Pupils are 7 mm bilaterally and sluggishly reactive. Mucous membranes are dry. An immediate electrocardiogram reveals sinus tachycardia with a QRS duration of 165 msec and a prominent terminal R wave in lead aVR. Which of the following are the most appropriate immediate simultaneous steps in the stabilization of this patient? (Select 3)

  1. Endotracheal intubationAnswer
  2. Intravenous lorazepamAnswer
  3. Intravenous sodium bicarbonateAnswer
  4. D
    Intravenous physostigmine
  5. E
    Obtain a non-contrast computed tomography scan of the head

Answer

The correct steps are endotracheal intubation, intravenous lorazepam, and intravenous sodium bicarbonate.
This patient presents with a severe mixed overdose (amitriptyline and diphenhydramine) resulting in status epilepticus, respiratory failure, and severe sodium channel blockade (QRS of 165 msec). Initial stabilization requires a simultaneous, multi-pronged approach. First, the patient's actively seizing state, low respiratory rate, and hypoxia mandate immediate endotracheal intubation for airway protection and ventilation. Second, the seizures must be aborted immediately with intravenous lorazepam, as prolonged seizing causes metabolic acidosis that further increases TCA-mediated cardiac toxicity. Third, the markedly widened QRS complex indicates impending ventricular dysrhythmia due to myocardial sodium channel blockade; intravenous sodium bicarbonate is the specific antidote required to narrow the QRS and stabilize the cardiac membrane.

Step-by-Step Solution

1
Assess airway, breathing, and circulation (ABCs).
The patient is hypoxic (SpO2 88%), hypoventilating (RR 8/min), and has an unprotected airway due to active seizures.
Endotracheal intubation is required immediately to secure the airway, ensure adequate oxygenation, and prevent aspiration.
2
Address the active status epilepticus.
Intravenous lorazepam should be administered.
Seizures exacerbate metabolic acidosis, which in turn worsens the cardiac toxicity of tricyclic antidepressants. Benzodiazepines are the first-line therapy to abort seizures.
3
Evaluate the electrocardiogram and treat potential fatal arrhythmias.
The ECG shows a widened QRS complex (165 msec) and an R wave in aVR, classic for TCA toxicity. Intravenous sodium bicarbonate should be given.
Sodium bicarbonate overcomes sodium channel blockade by providing a high sodium load and alkalinizing the serum, which favors the non-ionized form of the drug, thus narrowing the QRS and preventing arrhythmias.

Key Concept

Simultaneous resuscitation in severe tricyclic antidepressant (TCA) overdose requires airway protection, seizure control with benzodiazepines, and QRS narrowing with sodium bicarbonate.
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Topics

Initial Stabilization and Triage

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