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Phencyclidine Poisoning, Emergency Medicine

Basics

Description

- Drugs of abuse: - Cocaine - Amphetamines - Designer drugs: - Methcathinone ( "Cat " ť) - "Ecstasy " ť - "Ice " ť (methamphetamine)

  • 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 dustWicky stickWicky weedWacky weedWetIllyEmbalming fluidSherman

Exposure in toddlers reported via passive exposure ‚

Diagnosis

Signs and Symptoms

  • CNS:Altered mental statusAgitationBizarre/violent behaviorBelligerenceComaSeizuresNystagmus (vertical, horizontal, or rotatory)
  • Cardiovascular:
  • Musculoskeletal:Traumatic injury (decreased pain perception)Rhabdomyolysis (due to vigorous muscular contraction)
  • Vital signs:

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:CocaineAmphetaminesDesigner drugs:Methcathinone ( "Cat " ť) "Ecstasy " ť "Ice " ť (methamphetamine)AlcoholsKetamineSympathomimetics
  • Drugs that cause nystagmus:LithiumCarbamazepineSedative " “hypnoticsAlcoholsPhenothiazinesDextromethorphan

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:BenzodiazepinesButyrophenones (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