PCP Toxicity Clinical Presentation

The dissociative effects of phenylcyclohexyl piperidine (PCP), also known as phencyclidine, cause patients to have disorganized thought processes, including delirium, amnesia, paranoia, and dysphoria. Therefore, obtaining a reliable history may not be possible. In addition, because PCP is frequently an adulterant, patients are unlikely to know that they have ingested PCP. The patient's friends and family should be questioned, if possible, to gain a greater understanding of the situation.

Diagnosis of PCP intoxication is generally made clinically. PCP exposure is suggested by the patient's fluctuating behavior, nystagmus, motor disturbances, and autonomic stimulation.

The presentation of patients with PCP intoxication widely varies from inebriated and calm to agitated and, in some cases, extremely violent. An important diagnostic clue is nystagmus (lateral, horizontal, or rotatory). A large case series demonstrated nystagmus in 57% of patients with PCP intoxication, although smaller studies have found an incidence of 85% or higher. ^[14] Many CNS depressants can produce nystagmus when taken in high doses; however, the patient is generally sedated when nystagmus is observed. In PCP exposure, the patient may have nystagmus when he or she is awake and agitated. Additional autonomic effects at low doses (less than 5 mg) include hypertension, tachycardia, tachypnea with shallow breathing, salivation, flushing, and diaphoresis.

Central and peripheral nervous system effects include generalized numbness of extremities, loss of muscular coordination, and mental status can vary from stimulation and euphoria to depression and coma, which occurs in a dose-related manner. At high doses (10 mg or more) blood pressure, heart rate and respirations may fall. This is often accompanied by nausea, vomiting, blurred vision, drooling, ataxia and dizziness.

Patients may demonstrate bizarre posturing or facial expressions. Motor disturbances include the following dystonic reactions:

• Opisthotonos

• Torticollis

• Tortipelvis

• Facial grimacing

• Myoclonic movements

• Tremor

• Hyperactivity

• Athetosis

• Stereotypies

• Catalepsy

Psychobehavioral features of PCP intoxication often mimic symptoms of schizophrenia and can include delusions, hallucinations, acute anxiety, paranoia, disorganized thinking, violence, and a sensation of distance from one’s environment. ^[15] Elevation of anxious symptoms is frequently experienced. Long-term abuse of PCP may produce memory loss, speech difficulties, depression, and weight loss. Addiction to and withdrawal from PCP can occur after chronic use and manifest as craving and compulsive PCP-seeking behavior. ^[16]

During acute presentations in the emergency department, PCP abusers may become violent or suicidal and should be seen as a danger to themselves and/or others. High doses of PCP can cause seizures, coma, hyperthermia and death (frequently related to unintentional injury or suicide while intoxicated). Coma is often related to substances like alcohol or benzodiazepines that can enhance the sedative effects of PCP. ^[17]

The evaluation of PCP-intoxicated patients with actual or suspected trauma may be challenging because of the dissociative anesthetic effects that can mask signs and symptoms (eg, abdominal pain or those associated with hidden injuries). Like ketamine, PCP is thought to prevent the integration of sensory input to create meaningful responses. Because of the analgesic effects of PCP and lack of normal pain response, PCP-intoxicated patients have sometimes been described as having extraordinary strength. PCP-intoxicated patients have broken handcuffs and fractured bones in the process.

Children may inhale PCP fumes in their environments, or they may ingest or have topical exposure to PCP in their surroundings. Most parents who accompany their children for treatment of PCP exposure deny the possibility of their child's drug intoxication. Children exposed to PCP typically have symptoms similar to those of adults and can exhibit diminished response to tactile and verbal stimuli, bizarre behavior, ataxia, nystagmus, expressionless stare, dystonic posturing, irritability, poor feeding, seizures, and possibly miosis and hypertension. ^[18]

Incidences of hallmark findings in 1000 patients with PCP intoxication are as follows: ^[11]

• Nystagmus - 57.4%

• Hypertension - 57%

Incidences of sensorium findings in 1000 patients with PCP intoxication are as follows:

• Alert and oriented - 45.9%

• Acute brain syndrome - 36.9%

• Unconsciousness - 10.6%

• Lethargy, stupor, or both - 6.6%

Incidences of behavioral findings in 1000 patients with PCP intoxication are as follows:

• Violence - 35.4%

• Agitation - 34%

• Bizarreness - 28.8%

• Hallucinations, delusions, or both - 18.5%

• Muteness and stare - 11.7%

• Nudism - 3.3%

• None - 3.5%

Incidences of motor findings in 1000 patients with PCP intoxication are as follows:

• Generalized rigidity - 5.2%

• Grand mal seizures - 3.1%

• Localized dystonias - 2.4%

• Facial grimacing - 1.7%

• Athetosis - 1.3%

Incidences of cholinergic findings in 1000 patients with PCP intoxication are as follows:

• Diaphoresis - 3.9%

• Bronchospasm - 2.1%

• Pupils smaller than 1 mm - 2.1%

• Hypersalivation - 1.7%

• Bronchorrhea - 0.6%

Incidences of anticholinergic findings in 1000 patients with PCP intoxication are as follows:

• Pupils larger than 4 mm - 6.2%

• Urinary retention - 2.4%

Incidences of abnormal vital signs in 1000 patients with PCP intoxication are as follows:

• Tachycardia - 30%

• Hypothermia - 6.4%

• Apnea - 2.8%

• Hyperthermia - 2.6%

• Cardiac arrest - 0.3%

• Hypotension - 1.6%

Ketamine

Ketamine produces physical effects similar to PCP; however, symptoms are often of shorter duration. The hallmark of ketamine is its dissociative effect. Ketamine-provoked sensations are dose-related and range from a pleasant feeling of floating in a colorful “wonder world” (“K-land”) to the terrifying feeling of complete sensory detachment similar to a near-death or out of body experiences (“K-hole”). ^[19]

Other symptoms that can occur with ketamine intoxication include the following: ^[1]

• Increased intracranial and intraocular pressures, decreased seizure threshold, dizziness

• Neuromuscular disturbances, including muscle rigidity, slurred speech, blank stare, loss of coordination, numbness, polyneuropathy, diplopia, and nystagmus

• Effects on the autonomic nervous system at low doses (eg, bronchodilation, hypersalivation, hyperthermia, elevated blood pressure and heart rate); respiratory and cardiac arrest (at high doses)

• Psychobehavioral symptoms (eg, sense of invulnerability/exaggerated strength, aggressive/violent behavior, hallucinations, delirium, amnesia, depression, long-term memory loss, cognitive deficits); tolerance and dependence (with chronic use)