A 37-year-old man is brought to the emergency department by police officers. He was found naked at a traffic signal, cursing at drivers and assaulting nearby pedestrians. The patient has a long history of abusing multiple substances and has been admitted to the hospital several times with a similar presentation. He has epilepsy and type 2 diabetes mellitus. Attempts to elicit a history from the patient prove unsuccessful because he is highly agitated and combative. He keeps repeating, "They are all out to get me. They are coming through the walls, ready to kill me." The patient alternates between screaming and pounding on the walls. Temperature is 38.3 C (100.9 F), blood pressure is 148/100 mm Hg, pulse is 98/min, and respirations are 16/min. Physical examination shows ataxia, nystagmus, and muscle rigidity. Which of the following is the most appropriate next step in management of this patient?

Question

A 37-year-old man is brought to the emergency department by police officers.  He was found naked at a traffic signal, cursing at drivers and assaulting nearby pedestrians.  The patient has a long history of abusing multiple substances and has been admitted to the hospital several times with a similar presentation.  He has epilepsy and type 2 diabetes mellitus.  Attempts to elicit a history from the patient prove unsuccessful because he is highly agitated and combative.  He keeps repeating, "They are all out to get me.  They are coming through the walls, ready to kill me."  The patient alternates between screaming and pounding on the walls.  Temperature is 38.3 C (100.9 F), blood pressure is 148/100 mm Hg, pulse is 98/min, and respirations are 16/min.  Physical examination shows ataxia, nystagmus, and muscle rigidity.  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

Explanation: This patient's presentation suggests phencyclidine (PCP) intoxication. PCP acts on: N-methyl-D-aspartate receptors, particularly in the hippocampus and limbic system (causing excitatory and psychotic effects) dopamine, norepinephrine, and serotonin receptors (causing adrenergic and dopaminergic effects) the sigma receptor complex (causing psychotic and anticholinergic effects). Therefore, PCP intoxication commonly presents with severe agitation, delusions of enhanced strength, psychosis (eg, paranoia, hallucinations), analgesia, and aggression. Physical examination findings include multidirectional nystagmus (horizontal, vertical, and/or rotary), hypertension, tachycardia, and disorientation. Severe cases may present with hyperthermia, ataxia, muscle rigidity, seizures, and coma. The treatment of PCP intoxication involves supportive management and targeted treatment of agitation and aggression to maintain safety. Benzodiazepines are the preferred treatment of PCP-associated agitation. Benzodiazepine agents available in a parenteral formulation (eg, lorazepam, diazepam) are preferred because patients are often so agitated that they are unable to take medications by mouth. (Choice A) Dexmedetomidine is an agonist at the alpha-2 receptor that is commonly used in the intensive care unit and for procedural sedation. It is not typically used in the treatment of PCP intoxication. (Choice B) Dimercaprol is a chelating agent that may be used to treat lead poisoning. Lead poisoning can, in extremely high doses, lead to encephalopathy; however, it more commonly presents with gastrointestinal (eg, abdominal pain, constipation), neurologic (eg, cognitive deficits, neuropathy), and hematologic (eg, anemia) abnormalites and is unlikely to cause recurrent presentations. (Choice C) Fomepizole is an alcohol dehydrogenase inhibitor used in cases of ethylene glycol or methanol toxicity, which are unlikely to present as acute episodes of psychosis, nystagmus, and muscle rigidity. (Choice E) Phentolamine is an alpha-adrenergic antagonist that may be used in specific cases of hypertensive emergencies (eg, pheochromocytoma). (Choice F) Antipsychotics may lower the seizure threshold and must be used with caution in patients who have seizure disorders. (Choice G) Urinary acidification, which increases PCP clearance, is no longer recommended as a treatment for PCP intoxication because it is largely ineffective (only increases clearance by 1%) and increases the risk for acidosis and renal damage. Educational objective: Phencyclidine intoxication presents with severe agitation, delusions of enhanced strength, psychosis, analgesia, multidirectional nystagmus, hypertension, tachycardia, and disorientation. Agitation and aggression are managed with benzodiazepines. References: Phencyclidine intoxication case series study. (http://www.ncbi.nlm.nih.gov/pubmed/25502414)

A 37-Year-Old Man Is Brought to the Emergency Department by Police