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Sympathomimetic Poisoning, Emergency Medicine

Basics

Description

- Other: - Dilated pupils - Dry mucous membranes - Urinary retention may cause enlarged bladder. - Needle track marks or abscesses on extremities should be sought. - Increased or decreased bowel sounds - The presence of diaphoresis and bowel sounds may help to differentiate sympathomimetic toxicity from anticholinergic poisoning.

- Assess history for possible sympathomimetic agents: - Cold preparations - Prescription amphetamines - Recreational drug use

- Assess for possible coingestions - Evaluate for symptoms of end organ injury: - Chest pain - Shortness of breath - Headache, confusion, and vomiting

- Hypotension and respiratory distress may precede cardiovascular collapse - Evaluate for associated conditions: - Cellulitis and soft tissue infections - Diastolic cardiac murmurs or unequal pulses - Examine carefully for trauma - Pneumothorax from inhalation injury - Focal neurologic deficits

- Monitor vital signs: - Increased temperature (>40 °C possible): - Core temperature recording essential - Peripheral temperature may be cool - Indication for urgent cooling - Ominous prognostic sign

- ECG: - Signs of cardiac ischemia - Ventricular tachydysrhythmias - Reflex bradycardia

- Hyperthermia: - Benzodiazepines if agitated - Active cooling if temperature >40 °C: - Tepid water mist - Evaporate with fan

- Recognize rhabdomyolysis and hyperkalemia - Avoid physical restraints in agitated patients if possible - Consider associated emergency conditions: - Chest pain " acute coronary syndrome - Infection in altered patients with fevers and history of IV drug use - Traumatic injury with methamphetamine abuse

  • Direct or indirect stimulation of adrenergic receptors in sympathetic and central nervous systems
  • Often no correlation between dosage and degree of toxicity
  • Cocaine may also block sodium channels of cardiac myocytes, leading to "tricyclic " or class 1a " type dysrhythmias.
  • Sympathomimetic poisoning in children may present similarly to meningitis or other systemic illness.
  • Urinary toxicology screening may be only way to discover sympathomimetic poisoning in children presenting with altered mental status.
  • Methylphenidate (Ritalin, Concerta) and other sympathomimetics used for ADHD may cross-react with altered mental status.

Etiology

  • Sympathomimetic toxicity can result from use of any sympathetically active drug, including:All amphetamines, methamphetamines, and derivatives (ecstasy, MDMA)CocaineSynthetic cathinones "Bath Salts "Phencyclidine (PCP)Lysergic acid diethylamide (LSD)Decongestants (rare)
  • Drug delivery routes: Inhalation, injection, snorting, or ingestion

Diagnosis

Signs and Symptoms

  • Vital signs:Tachycardia:Bradycardia possible for cocaine and some other decongestantsIncreased BP:Severely intoxicated patients may be hypotensive.TachypneaHyperthermia:Often present, may be severe, and is often overlooked
  • CNS:AnxietyHeadacheAgitationAltered mentationDiaphoresisSeizuresStrokeDystonia (rare)
  • Cardiovascular:PalpitationsChest painMyocardial ischemia or infarctionTachydysrhythmiasCardiovascular collapseMurmur (e.g., endocarditis)
  • Other:Dilated pupilsDry mucous membranesUrinary retention may cause enlarged bladder.Needle track marks or abscesses on extremities should be sought.Increased or decreased bowel soundsThe presence of diaphoresis and bowel sounds may help to differentiate sympathomimetic toxicity from anticholinergic poisoning.

History

  • Assess history for possible sympathomimetic agents:Cold preparationsPrescription amphetaminesRecreational drug use
  • Assess for possible coingestions
  • Evaluate for symptoms of end organ injury:Chest painShortness of breathHeadache, confusion, and vomiting

Physical Exam

  • Common findings include:AgitationTachycardiaDiaphoresisMydriasis
  • Severe intoxication characterized by:TachycardiaHypertensionHyperthermiaAgitated deliriumSeizuresDiaphoresis
  • Hypotension and respiratory distress may precede cardiovascular collapse
  • Evaluate for associated conditions:Cellulitis and soft tissue infectionsDiastolic cardiac murmurs or unequal pulsesExamine carefully for traumaPneumothorax from inhalation injuryFocal neurologic deficits

Essential Workup

  • Monitor vital signs:Increased temperature (>40 °C possible):Core temperature recording essentialPeripheral temperature may be coolIndication for urgent coolingOminous prognostic signBP:Severe hypertension can lead to cardiac and neurologic abnormalities.Late in course, hypotension may supervene.
  • ECG:Signs of cardiac ischemiaVentricular tachydysrhythmiasReflex bradycardia

Diagnosis Tests & Interpretation

Lab

  • Urinalysis for:
  • Electrolytes, BUN/creatinine, glucose:Hypoglycemia may contribute to altered mental status.Acidosis may accompany severe toxicity.Rhabdomyolysis may cause renal failure.Hyperkalemia " life-threatening consequence of acute renal failure
  • Coagulation profile to monitor for potential disseminated intravascular coagulation (DIC):
  • Creatine phosphokinase (CPK):Markedly elevated in rhabdomyolysis
  • Urine toxicology screen:For other toxins with similar effects (e.g., cocaine)Some amphetamine-like substances (e.g., synthetic cathinones, MDMA) may not be detected.
  • Salicylate and acetaminophen levels if suicide attempt a possibility or if OTC medications ingested (e.g., cough, cold)
  • Venous blood gas, ABG

Imaging

  • CXR:Adult respiratory distress syndromeNoncardiogenic pulmonary edema
  • Head CT for:Significant headacheAltered mental statusFocal neurologic signsSubarachnoid hemorrhage, intracerebral bleed

Diagnostic Procedures/Surgery

Lumbar puncture for:

  • Suspected meningitis (headache, altered mental status, hyperpyrexia)
  • Suspected subarachnoid hemorrhage and CT normal

Differential Diagnosis

  • Sepsis
  • Thyroid storm
  • Serotonin syndrome
  • Neuroleptic malignant syndrome
  • Pheochromocytoma
  • Subarachnoid hemorrhage
  • Drugs that cause delirium:AnticholinergicsTricyclic antidepressantsSympathomimeticsEthanol withdrawalSedative/hypnotic withdrawalHallucinogensPCP
  • Drugs that cause hypertension and tachycardia:SympathomimeticsAnticholinergicsEthanol withdrawalPCPCaffeineMonoamine oxidase inhibitorsTheophyllineNicotine
  • Drugs that cause seizures:CamphorCarbamazepineCarbon monoxideChlorinated hydrocarbonsCholinergicsCyanideEthanol withdrawalHypoglycemicsIsoniazidLeadLithiumLocal anestheticsPhenothiazinesPropoxypheneSalicylatesSedative/hypnotic withdrawalStrychnineSympathomimeticsTheophyllineTricyclic antidepressants

Treatment

Pre-Hospital

  • Patient may be uncooperative or violent.
  • Secure IV access.
  • Protect from self-induced trauma.

Initial Stabilization/Therapy

  • ABCs
  • Establish IV 0.9% NS access
  • Cardiac monitor
  • Naloxone, dextrose (or Accu-Chek), and thiamine if altered mental status

Ed Treatment/Procedures

  • Decontamination:Gastric lavage not routinely recommended:May consider if recent (within 1 hr) of life-threatening ingestion.Activated charcoal not routinely recommended.Consider activated charcoal with sorbitol in 1st dose if administered.Consider activated charcoal with body stuffer or body packer ingestions.Whole-bowel irrigation with polyethylene glycol solution " electrolyte solution for body packers
  • Hypertensive crisis:Initially administer benzodiazepines if agitated.α-blocker (phentolamine) as 2nd-line agentNicardipine or nitroglycerin IV for severe HTN unresponsive to benzodiazepinesNitroprusside can also be used for severe, unresponsive HTNAvoid ²-blockers, which may exacerbate HTN due to unopposedα activity
  • Agitation, acute psychosis:Administer benzodiazepines.Use butyrophenones (e.g., haloperidol) with caution to manage agitation:May lower seizure thresholds and may prolong QT duration
  • Dysrhythmias:Sodium bicarbonate IV push is treatment of choice for ventricular dysrhythmias indicative of sodium channel blocking (i.e., widened QRS complex).Lidocaine for ventricular dysrhythmias refractory to alkalinization, benzodiazepines, and supportive care
  • Hyperthermia:Benzodiazepines if agitatedActive cooling if temperature >40 °C:Tepid water mistEvaporate with fan
  • Paralysis:Indicated if muscle rigidity and hyperactivity contributing to persistent hyperthermiaNondepolarizing paralytic preferred
  • Rhabdomyolysis:Administer benzodiazepines.Hydrate with 0.9% NS.Maintain urine output at 1 " 2 mL/minHemodialysis (if acute renal failure and hyperkalemia occur)
  • Seizures:Maintain airwayAdminister benzodiazepinesPhenobarbital if unresponsive to benzodiazepines

Medication

  • Activated charcoal: 1 " 2 g/kg up to 100 g PO
  • Dextrose: D50W 1 amp: 50 mL or 25 g (peds: 1 to 2 mL/kg of D25W; infants: 2.5 to 5.0 mL/kg of D10%) IV
  • Diazepam (benzodiazepine): 5 " 10 mg (peds: 0.2 " 0.5 mg/kg) IV. Not recommended <6 months of age
  • Lorazepam (benzodiazepine): 2 " 6 mg (peds: 0.03 " 0.05 mg/kg) IV
  • Nicardipine IV infusion at 5 mg/h titrate by 2.5 mg/h q5min to max. 15 mg/h
  • Nitroprusside: 0.5 " 10 Όg/kg/min IV (titrated to BP)
  • Phenobarbital: 15 " 20 mg/kg at 25 " 50 mg/min until cessation of seizure activity; monitor for respiratory depression. Safety not established <6 years of age
  • Phentolamine: 1 " 5 mg IV over 5 min (titrated to BP)
  • Sodium bicarbonate: 1 or 2 amps (50 mEq/amp) (peds: 1 " 2 mEq/kg) IV push

Follow-Up

Disposition

Admission Criteria

  • Admit all body packers or stuffers to hospital.
  • Severe manifestations of toxicity to monitored bed:SeizuresDysrhythmiasHyperthermiaRhabdomyolysisSevere hypertensionAltered mental status
  • Ischemic chest pain

Discharge Criteria

Mildly intoxicated patients can be observed and treated in ED until resolution of clinical manifestations.

Followup Recommendations

Patients may need referral for chemical dependency rehab and detoxification

Pearls and Pitfalls

  • Admit patients with severe or persistent symptoms
  • Hyperthermia above 40 °C may be life threatening:Treat with aggressive sedation and active cooling
  • Recognize rhabdomyolysis and hyperkalemia
  • Avoid physical restraints in agitated patients if possible
  • Consider associated emergency conditions:Chest pain " acute coronary syndromeInfection in altered patients with fevers and history of IV drug useTraumatic injury with methamphetamine abuse
  • Benzodiazepines are 1st-line therapy in symptomatic sympathomimetic intoxication

Additional Reading

  • Carvalho M, Carmo H, Costa VM, et al. Toxicity of amphetamines: An update. Arch Toxicol. 2012;86:1167 " 1231.
  • Greene SL, Kerr F, Braitberg G. Review article: Amphetamines and related drugs of abuse. Emerg Med Australas. 2008;20:391 " 402.
  • Prosser JM, Nelson LS. The toxicology of bath salts: A review of synthetic cathinones. J Med Toxicol. 2012;8:33 " 42.
  • Schep LJ, Slaughter RJ, Beasley DM. The clinical toxicology of metamfetamine. Clin Toxicol (Phila). 2010;48:675 " 694.

Codes

ICD9

971.2 Poisoning by sympathomimetics [adrenergics]

ICD10

T44.901A Poisn by unsp drugs aff the autonm nervous sys, acc, init

SNOMED

  • 45536007 poisoning by sympathomimetic drug (disorder)