Free Sample COMAT Practice Questions
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Below is a free practice question for psychiatry, however our COMAT qbank contains questions for all 8 subjects.
Your Free COMAT Practice Question
An 18-year-old male is brought to the emergency department by his friends because of extreme agitation, aggressiveness, and auditory hallucinations. His friends state that he smoked “a little marijuana” before exhibiting these symptoms. He has no known psychiatric history. He is currently oriented to person only and appears to be very distracted, repeatedly looking toward a corner of the room as if someone is there. Vital signs reveal a heart rate of 130/min. Physical examination reveals vertical and horizontal nystagmus bilaterally. As his symptoms are unlikely due to marijuana alone, exposure to another drug mixed with marijuana is suspected. This other drug is most likely:
- A. cocaine
- B. lysergic acid diethylamide
- C. methamphetamine
- D. phencyclidine
- E. Salvia divinorum
The Answer and Explanation
Did you get it right? The correct answer is: D
The patient is presenting with symptoms suspicious for gastric outlet obstruction. Her history of vague This patient is presenting with evidence of acute phencyclidine (PCP; 1-(1-phenylcyclohexyl) piperidine hydrochloride) intoxication, as suggested by his psychomotor agitation, aggressive behavior, disorientation, tachycardia, nystagmus, and hallucinations (auditory and likely visual). PCP is a dissociative anesthetic taken recreationally for its hallucinogenic properties. It is available in many forms (eg, powder, crystal, liquid, tablets) and is most commonly consumed by inhalation, usually via laced cigarettes or marijuana. The most common street name for PCP is “angel dust.”
PCP intoxication can produce a wide range of effects, depending on the amount ingested, route of administration, patient susceptibility, and presence of co-consumed drugs. Hypertension and tachycardia are common. Central nervous system (CNS) stimulation or depression may occur, although psychomotor agitation is more common and is often associated with hallucinations. Violent, aggressive behavior is also frequently observed. Horizontal, vertical, and/or rotatory nystagmus is common, with rotatory nystagmus being strongly suggestive of PCP intoxication. Seizures, stupor, or coma may occur with severe intoxication.
Laboratory abnormalities that may be seen with PCP intoxication include an elevated creatine kinase level (due to rhabdomyolysis), elevated liver transaminases, hyperuricemia, and hypoglycemia. PCP levels in the urine or blood can be used to confirm the diagnosis, although the results are not usually immediately available.
Management of acute PCP intoxication begins with resuscitative efforts, focusing on the “Airway, Breathing, and Circulation.” With severe intoxication, tracheal intubation may be required for airway protection. After initial stabilization, psychomotor agitation should be controlled, usually with benzodiazepines and a quiet environment. An antipsychotic, such as haloperidol, can be used as adjunctive therapy when benzodiazepines are inadequate. Most patients improve with supportive care. Gastrointestinal decontamination (eg, activated charcoal, nasogastric suction) is generally not recommended for PCP intoxication.
| Common Drugs of Abuse | |
| Drug | Signs and Symptoms of Intoxication |
| Barbiturates | Nystagmus, respiratory depression, confusion, hypotension, drowsiness, slurred speech, incoordination, ataxia |
| Benzodiazepines | Disinhibition, mood lability, respiratory depression, confusion, hypotension, drowsiness, slurred speech, incoordination, ataxia |
| Cannabis | Euphoria, anxiety, perceptual disturbances (eg, sensation of slowed time), dry mouth, increased appetite, conjunctival injection |
| Cocaine | Psychomotor agitation, euphoria, aggressiveness, dilated pupils, hallucinations (often auditory or tactile), hypertension, tachycardia |
| LSD | Altered perceptual states (eg, visual hallucinations, delusions, distorted body image, synesthesias), dilated pupils, euphoria, flashbacks, “bad trip” (panic reaction) |
| Methamphetamines | Euphoria, dilated pupils, perspiration, tachycardia, hypertension, hallucinations (often auditory or tactile), tooth decay, paranoid delusions |
| Opioids | CNS and respiratory depression, constricted pupils, constipation, drowsiness, nausea/vomiting |
| PCP | Nystagmus (vertical, horizontal, and/rotatory), psychomotor agitation, aggression, hallucinations (often auditory, may be visual or tactile), hypertension, tachycardia |
| CNS = central nervous system; LSD = lysergic acid diethylamide; PCP = phencyclidine. | |
Incorrect Answer Explanations:
Answer A: Cocaine intoxication often causes significant psychological and behavioral changes. Psychological symptoms can include euphoria, interpersonal sensitivity, anxiety, anger, impaired social and occupational functioning, hypervigilance, and poor judgment. Physiological symptoms often include dilated pupils, tachycardia, hypertension, nausea/vomiting, weight loss, muscle weakness, respiratory depression, possible seizures, confusion, chest pain, arrhythmias, and dystonia. Although cocaine intoxication may cause hallucinations, psychomotor agitation, aggressiveness, and tachycardia (as seen in this patient), it does not cause nystagmus. In addition, this patient has no evidence of euphoria or dilated pupils, which are very common effects of cocaine.
Answer B: Lysergic acid diethylamide (LSD) intoxication typically causes anxiety, depression, dilated pupils, delusions, visual hallucinations, and flashbacks. Individuals often develop synesthesias (hearing colors and seeing sounds) and panic symptoms. Orientation is maintained in the majority of individuals, in contrast to this patient who is oriented to person only. Although this patient likely has visual hallucinations, LSD does not usually lead to aggression, severe agitation, or nystagmus.
Answer C: Methamphetamine intoxication typically causes apprehension, difficulty concentrating, tachycardia, hypertension, dilated pupils, fever, euphoria, possible hallucinations, restlessness, irritability, and prolonged wakefulness. Although this patient has hallucinations and tachycardia, he has no evidence of pupillary abnormalities, fever, or euphoria, and methamphetamine intoxication does not usually cause nystagmus.
Answer E: Salvia divinorum intoxication typically causes hallucinations, euphoria, and perceptual distortions that last for a short time (≤ 1–2 hours). Sympathomimetic effects (such as tachycardia) may occur but are mild. Although this patient has hallucinations and tachycardia, his tachycardia (heart rate of 130/min) would not be considered mild. Furthermore, S. divinorum does not usually cause aggressive behavior, severe agitation, or nystagmus.
Bottom Line
Phencyclidine is a dissociative anesthetic that is most commonly smoked for its hallucinogenic properties. Typical manifestations include nystagmus (vertical, horizontal, and/or rotatory), psychomotor agitation, aggressive behavior, and hallucinations.
COMBANK Insight
PCP has 3 main sites of action in the CNS:
N-methyl-D-aspartate (NMDA) receptor complex: PCP is a noncompetitive antagonist of NMDA receptors and has high affinity for these NMDA receptor complexes. It is this antagonism that produces acute psychosis similar to schizophrenia and leads to excessive release of excitatory neurotransmitters (eg, glutamate, glycine, aspartate), which can cause agitation and seizures.
Dopamine, norepinephrine, and serotonin reuptake complex: PCP inhibits the reuptake of these neurotransmitters, which contributes to the adrenergic and dopaminergic effects of PCP intoxication.
Sigma receptor complex: PCP binding to the sigma receptor may explain, in part, the psychotic, anticholinergic, and movement abnormalities seen with PCP intoxication.
For more information, see:
- Phencyclidine (PCP) intoxication in adults: UpToDate
- Intoxication from LSD and other common hallucinogens: UpToDate
- Phencyclidine toxicity: StatPearls
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