JJ is a 20-year-old female who presents to the ED via EMS after being rescued from a house fire. Upon presentation, dark brown urine is noted on the sheets from EMS, as well as second-degree burns on her torso and left upper and lower extremities. During the initial survey, the patient has trouble with verbal responses and shows signs of muscle weakness. She also shows signs of smoke inhalation injury and cyanosis. As a result, the team decides to intubate to ensure protection of the patient’s airway and the potential for carbon monoxide poisoning.

PMH: Substance Use Disorder (based on recent injection marks on feet)

Current Medications: unknown

Pertinent Labs:

• Vitals: BP 100/50 mmHg; HR: 70; RR: 23; Temp: 100.4°F; SpO2: 97%
• Weight 67 kg; Height: 64 in
• Initial Labs: Sodium 136 meq/L, Potassium 5.6 meq/L, Chloride 100 meq/L, Calcium 9.2 mg/dL, BUN 50 mg/dL, SCr 2.4 mg/dL, Glucose 110 mg/dL, CK 50,000 units/L

Based on the patient’s presentation and labs, which of the following paralytics would be inappropriate for use in rapid sequence intubation? (Multiple choice)

A. Rocuronium

B. Vecuronium 

C. Succinylcholine 

D. Atracurium

Rationale:

Explanation:

Patients with severe burn injuries are at an increased risk for hyperkalemia due to an efflux of potassium into the plasma from intracellular stores as a result of damage to cells. Additionally, tissue necrosis from burn injuries can lead to the breakdown of muscle tissue and increases the risk of rhabdomyolysis. This complication is characterized by the release on intracellular muscle components into the blood, including potassium. Rhabdomyolysis may present with the sign and symptoms of muscle pain, muscle weakness, and brown urine resembling tea due to myoglobinuria.

Succinylcholine is a depolarizing neuromuscular blocking agent used to facilitate intubation in rapid sequence intubation. As a depolarizing agent, it causes constant excitation of the motor endplate at the neuromuscular junctions until exhaustion, which results in skeletal muscle paralysis. This excitation can be seen as transient fasciculations, or muscle twitches, prior to paralysis. Due to these fasciculations, potassium leaves the muscle cells resulting in an increase in extracellular potassium concentrations. Typically, the increase is minimal, approximately 0.5 mEq/L. However, in burn patients or patients predisposed to hyperkalemia, such as patients with rhabdomyolysis which our patient has, this increase can be exacerbated to 5 mEq/L. Our patient has demonstrated an increased SCr in conjunction with their rhabdomyolysis as well as hyperkalemia which would make this patient not a good candidate for a depolarizing agent.  As a result, succinylcholine is contraindicated in this patient population due to the burn injury, and a non-depolarizing neuromuscular blocking agent is preferred.

Correct Answer: C

NAPLEX Competencies Covered:

Area 1 (Obtain, Interpret, or Assess Data, Medical, or Patient Information), 1.5 Signs or symptoms of medical conditions, healthy physiology, etiology of diseases, or pathophysiology. Area 2 (Identify Drug Characteristics), 2.1 Pharmacology, mechanism of action, or therapeutic class. Area 3 (Develop or Manage Treatment Plans), 3.6 Drug contraindications, allergies, or precautions. 3.7 Adverse drug effects, toxicology, or overdose.