Phencyclidine Poisoning, Emergency Medicine

Basics

Description

Phencyclidine (PCP) is a dissociative anesthetic structurally related to ketamine:
- Causes decreased perception of pain and agitation
Half-life of 21 " “24 hr, but may be longer in overdose
Enterohepatic recirculation " ”recirculated into the stomach

Etiology

Drug of abuse:
- Frequently encountered as an adulterant of marijuana
Street names for PCP include:
- Angel dust
- Wicky stick
- Wicky weed
- Wacky weed
- Wet
- Illy
- Embalming fluid
- Sherman

Exposure in toddlers reported via passive exposure ‚

Diagnosis

Signs and Symptoms

CNS:
- Altered mental status
- Agitation
- Bizarre/violent behavior
- Belligerence
- Coma
- Seizures
- Nystagmus (vertical, horizontal, or rotatory)
Cardiovascular:
- HTN
- Tachycardia
Musculoskeletal:
- Traumatic injury (decreased pain perception)
- Rhabdomyolysis (due to vigorous muscular contraction)
Vital signs:
- Hyperthermia

History
How was the PCP consumed? ‚

Smoked with marijuana
Ingested

Physical Exam

Agitation
Coma
Hypertension
Tachycardia
Diaphoresis
Nystagmus (vertical, horizontal, or rotatory)
Hyperthermia
Vigorous muscular contraction

Essential Workup

Clinical diagnosis based on presentation supported by urine toxicology screen:
- Dextromethorphan and ketamine may give false positive.
Careful physical exam for occult trauma
Exclude other causes of altered mental status.

Diagnosis Tests & Interpretation

Lab

CBC
Electrolytes, BUN/creatinine, glucose
Urinalysis:
- Dip for myoglobin (rhabdomyolysis)
Creatine phosphokinase:
- If urine dip for blood is positive
Ethanol level

Imaging

Chest radiograph for aspiration pneumonia
Extremity/spine radiographs when there is associated trauma
CT of the head when there is head trauma/altered mental status

Differential Diagnosis

Drugs of abuse:
- Cocaine
- Amphetamines
- Designer drugs:
  - Methcathinone ( "Cat " ť)
  - "Ecstasy " ť
  - "Ice " ť (methamphetamine)
- Alcohols
- Ketamine
- Sympathomimetics
Drugs that cause nystagmus:
- Lithium
- Carbamazepine
- Sedative " “hypnotics
- Alcohols
- Phenothiazines
- Dextromethorphan

Treatment

Pre-Hospital

Use restraints/additional personnel to control combative patient. ‚

Initial Stabilization/Therapy

ABCs
IV
Cardiac monitor
Naloxone, thiamine, glucose (or Accu-Chek) if altered mental status
Protect patient and staff from injury.

Ed Treatment/Procedures

Maintain patient in a quiet place; avoid stimulation.
Physical restraints for violent patient
Sedation:
- Benzodiazepines
- Butyrophenones (haloperidol) theoretically can lower the seizure threshold.
Activated charcoal if oral coingestants
IV 0.9% normal saline for hydration, sodium bicarbonate/mannitol for rhabdomyolysis

Medication

First Line

Ativan (lorazepam): 2 mg IV increments
Diazepam: 5 mg IV increments

Second Line

Activated charcoal slurry: 1 " “2 g/kg up to 90 g PO
Dextrose: D50W 1 amp: 50 mL or 25 g (peds: D25W 2 " “4 mL/kg) IV
Mannitol: 25 " “50 g IV
Naloxone (Narcan): 2 mg (peds: 0.1 mg/kg) IV or IM initial dose
Sodium bicarbonate: 2 amps (50 mEq per amp) diluted in 1 L of D5W, given at 125 " “250 mL/h (for rhabdomyolysis) to urine pH of 7
Thiamine (vitamin B1): 100 mg (peds: 50 mg) IV or IM

Follow-Up

Disposition

Admission Criteria

Prolonged altered mental status
Significant traumatic injuries
Rhabdomyolysis
Hyperthermia

Discharge Criteria
Becomes lucid after a period of observation (6 hr) ‚

Followup Recommendations

Psychiatry or social work referral for suicidal ideation or chronic drug use ‚

Pearls and Pitfalls

PCP poisoning can lead to traumatic injuries that can become life threatening.
Adequate chemical restraints with benzodiazepines are needed to prevent excessive muscular activity leading to rhabdomyolysis.
Dextromethorphan is a common cause for a false-positive PCP urine toxicology screen.
Tramadol has been reported to cause a false-positive screen for PCP
Ketamine abuse presents with similar signs and symptoms of PCP abuse.

Additional Reading

Hahn ‚ I-H. Phencyclidine and ketamine. In: Erickson ‚ TB, Ahrens ‚ W, Aks ‚ SE, et al., eds. Pediatric Toxicology. New York, NY: McGraw-Hill; 2004:297 " “302.
Ly ‚ BT, Thornton ‚ SL, Buono ‚ C, et al. False-positive urine phencyclidine immunoassay screen result caused by interference by tramadol and its metabolites. Ann Emerg Med. 2012;59:545 " “547.
Pugach ‚ S, Pugach ‚ IZ. Overdose in infant caused by over-the-counter cough medicine. South Med J. 2009;102:440 " “442.
Wills ‚ B, Erickson ‚ T. Drug- and toxin-associated seizures. Med Clin North Am. 2005;89:1297 " “1321.

Codes

ICD9

968.3 Poisoning by intravenous anesthetics ‚

ICD10

T40.991A Poisoning by oth psychodyslept, accidental, init ‚

SNOMED

41136005 Phencyclidine poisoning

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