CURRENT Essentials of Critical Care.pdf

Chapter 16 Toxicology 233Ketamine & Phencyclidine (PCP)■ Essentials of Diagnosis• Ketamine: short-acting anesthetic; no respiratory or cardiovasculardepression, but hallucinations; analog of phencyclidine(PCP); both abused as hallucinogens• PCP usage declining, recently increasing ketamine abuse• Variable symptoms and signs; euphoria, agitation, psychosis, violentbehavior, seizures; fully alert to comatose• Nystagmus (horizontal, vertical, rotatory) 50% of PCP (rarewith ketamine); hypertension, tachycardia• Ketamine inhaled or injected; effects rare 1 hour; PCPsmoked, intranasal, or ingested; rapidly absorbed; half-life 7–72hours• Complicated by rhabdomyolysis, renal failure, concealed injuriesdue to violent behavior• Urine PCP level confirms diagnosis; serum creatine kinase levels,urine myoglobin■ Differential Diagnosis• Sympathomimetics• Long-acting hallucinogens (3,4-methylenedioxymethamphetamine(“ecstasy”), LSD• Sedative-hypnotics, alcohol; withdrawal from these• Head trauma, meningitis, encephalitis• Psychiatric disorders• Metabolic derangements■ Treatment• Ketamine generally none; rapid elimination• PCP: gastric lavage if suspected large ingestion within 1 houror co-ingestion suspected; follow with multidose activated charcoal• Supportive care for hypertension, tachycardia; treat hyperthermia• Treat seizures with benzodiazepines, phenytoin• IV fluids, mannitol, bicarbonate for rhabdomyolysis to reducerisk of renal failure• Avoid excessive stimulation; use benzodiazepines or haloperidolfor sedation■ PearlSome patients suspected of head trauma instead have PCP intoxication.ReferenceWeiner AL et al: Ketamine abusers presenting to the emergency department:a case series. J Emerg Med 2000;18:447. [PMID: 10802423]