A 24-year-old man is brought into the emergency department after a seizure an hour ago. The patient's friend, who witnessed the seizure, says, "We were at a party when he fell to the floor suddenly and started to convulse. He was acting strange before the seizure." The patient's seizure spontaneously resolved after approximately 2 minutes. He has no previous history of seizures or medical problems. Temperature is 37.4 C (99.3 F), blood pressure is 140/90 mm Hg, and pulse is 98/min. The patient is somnolent but easily arousable and follows instructions. Bilateral pupils are equal and reactive. The lungs are clear on auscultation, and heart sounds are normal. Muscle strength and deep tendon reflexes are normal. Bilateral plantar reflexes are downgoing. Laboratory results are as follows:
| Complete blood count | |
| Hemoglobin | 14.8 g/dL |
| Platelets | 400,000/mm³ |
| Leukocytes | 11,000/mm³ |
| Serum chemistry | |
| Sodium | 142 mEq/L |
| Potassium | 4.4 mEq/L |
| Chloride | 102 mEq/L |
| Bicarbonate | 20 mEq/L |
| Blood urea nitrogen | 20 mg/dL |
| Creatinine | 0.6 mg/dL |
| Calcium | 9.2 mg/dL |
| Magnesium | 2.0 mEq/L |
| Glucose | 140 mg/dL |
| Urinalysis | |
| Protein | none |
| Blood | large |
| Red blood cells | 0-1/hpf |
| Casts | none |
Electrocardiography shows sinus tachycardia. Urine toxicology is positive for phencyclidine. Noncontrast CT scan of the head is normal. Which of the following is most appropriate to prevent an adverse outcome in this patient?
This patient with a seizure from phencyclidine (PCP) has urinalysis evidence of blood with minimal red blood cells, raising suspicion for myoglobinuria due to rhabdomyolysis.
Rhabdomyolysis is characterized by the release of intracellular muscle components into the circulation after muscular injury. Most cases arise due to trauma, compression injury, infection, drug use (eg, PCP), or toxin exposure. Diagnosis is typically made when laboratory results show markedly elevated creatine kinase levels (usually >10,000 U/L). Urinalysis often reveals blood with no red blood cells, indicating myoglobinuria.
The major complication of rhabdomyolysis is acute kidney injury; early and aggressive fluid resuscitation with isotonic saline is required to increase renal perfusion and prevent intratubular cast formation.
(Choice A) Fosphenytoin can be used to treat status epilepticus, which is marked by a seizure lasting >5-10 minutes or serial seizures without a return to baseline consciousness between episodes. This patient had a single seizure that spontaneously remitted, likely due to acute PCP intoxication; he would not require medication at this time.
(Choice B) Loop diuretics (eg, furosemide) may worsen intravascular volume status and increase the risk of renal tubular cast formation. These medications should not be used to prevent acute kidney injury in rhabdomyolysis.
(Choice D) Naltrexone is an opioid antagonist used in the management of alcohol or opioid dependence. It is not useful in the treatment of PCP intoxication.
(Choice E) Sodium bicarbonate can be used to alkalinize the urine, which theoretically helps prevent cast formation. However, patients with rhabdomyolysis do not appear to have improved outcomes with urinary alkalinization. Saline infusion is the preferred treatment.
Educational objective:
Rhabdomyolysis is marked by muscular injury, which results in dramatic elevations in creatine kinase. The major complication of rhabdomyolysis is acute kidney injury due to myoglobinuria. Patients should receive early and aggressive isotonic saline infusion to improve volume status and prevent intratubular cast formation.