Rosen & Barkin's 5-Minute Emergency Medicine Consult (424 page)

• Acute toxicity:
  
  • Less common/serious than chronic toxicity
    
  • Neurologic (mild):
    
    • Weakness
      
    • Fine tremor
      
    • Lightheadedness
      
  • Neurologic (moderate):
    
    • Ataxia
      
    • Slurred speech
      
    • Blurred vision
      
    • Tinnitus
      
    • Weakness
      
    • Coarse tremor
      
    • Fasciculations
      
    • Hyper-reflexia
      
    • Apathy
      
  • Neurologic (severe):
    
    • Confusion
      
    • Coma
      
    • Seizure
      
    • Clonus
      
    • Extrapyramidal symptoms
      
  • GI:
    
    • Very common
      
    • Nausea/vomiting
      
    • Diarrhea
      
    • Abdominal pain
      
  • Cardiac:
    
    • Prolonged QT, ST depression
      
    • T-wave flattening
      most common
      ECG abnormality
      
    • U-waves
      
    • Serious dysrhythmias (rare)
      
• Chronic toxicity:
  
  • Neurologic:
    
    • Most common
      
    • Same symptoms as acute
      
    • Severe toxicity includes parkinsonism, psychosis, and memory deficits
      
  • Renal:
    
    • Nephrogenic diabetes insipidus
      
    • Interstitial nephritis
      
    • Distal tubular acidosis
      
    • Direct cellular damage
      
  • Dermatologic:
    
    • Dermatitis
      
    • Ulcers
      
    • Localized edema
      
  • Endocrine:
    
    • Hypothyroidism
      
  • Hematologic:
    
    • Leukocytosis
      
    • Aplastic anemia
      

• Time of last dose ingested
  
• Ingestion history:
  
  • Acute (1-time overdose)
    
  • Chronic (scheduled dosing)
    
  • Acute on chronic (overdose in patients who regularly take lithium)
    

Perform complete neurologic exam

• Lithium level: Goal = postdistribution:
  
  • Because of prolonged distribution, repeat every 2 hr to ensure trend
    
• Stratify patient into 1 of 3 categories of toxicity to interpret level and predict toxicity: Acute, acute on chronic, chronic:
  
  • Acute toxicity:
    
    • Intentional overdose in patient not previously taking lithium
      
    • Poor correlation between lithium level and symptoms because intracellular distribution has not yet occurred
      
    • Toxic levels may appear in asymptomatic patients
      
    • Lithium level >4 mEq/L may result in toxic sequelae because of slowed clearance
      
  • Acute on chronic toxicity:
    
    • Intentional or accidental overdose in patient on lithium therapy
      
    • Lithium level >3 mEq/L usually associated with symptoms
      
  • Chronic toxicity:
    
    • Patients on lithium therapy who progressively develop toxicity secondary to factors other than acute ingestion
      
    • Stronger correlation between lithium level and symptoms
      
    • Lithium level >1.5 mEq/L may correlate with toxicity
      

• Electrolytes, BUN, creatinine, and glucose levels to determine electrolyte disturbances/renal function
  
• Aspirin and/or acetaminophen levels as indicated by history
  
• Urinalysis:
  
  • Specific gravity
    

• Consider lithium toxicity with altered mental status and fasciculations
  
• Endocrine:
  
  • Hypoglycemia
    
• Toxicologic:
  
  • Cholinergic substances
    
  • Heavy-metal poisoning
    
  • Neuroleptic overdose
    
  • Black widow/scorpion envenomation
    
  • Strychnine poisoning
    

TREATMENT

• Transport all appropriate pill bottles to the hospital
  
• IV access, oxygen, and cardiac monitoring
  

• ABCs
  
• Secure IV access with 0.9% NS
  
• Cardiac monitor
  
• Naloxone, thiamine, dextrose (or Accu-Chek) if altered mental status
  
• Benzodiazepines for seizures
  

• Correct electrolyte abnormalities
  
• Maintain well-hydrated state
  
• Continuous cardiac monitoring
  
• Observe for neurologic changes
  
• Prevent absorption:
  
  • Consider gastric lavage only if patient presents within 1 hr of acute life-threatening ingestion and has protected airway
    
  • Activated charcoal:
    
    • Lithium is not adsorbed by charcoal
      
    • Administer 1 dose of activated charcoal if possible coingestants
      
  • Whole-bowel irrigation:
    
    • Polyethylene glycol (PEG) solution (GoLytely)
      
    • Sustained-release lithium products
      
    • Flushes lithium through gut
      
    • Administer (2 L/hr per nasogastric tube) until rectal effluent is clear
      
    • Contraindications include bowel obstruction or perforation, ileus or hypotension, and unprotected airway in obtunded or seizing patient
      
• Enhance elimination:
  
  • IV fluids:
    
    • Rapidly correct any pre-existing fluid deficit with 0.9% NS at 150–300 mL/hr (or 2× maintenance)
      
    • Saline hydration improves glomerular filtration and decreases proximal tubule reabsorption of lithium
      
    • Maintain urine output, 1–2 mL/kg/hr
      
    • Limited value once glomerular filtration rate maximized
      
    • Sodium bicarbonate offers no additional advantage
      
  • Loop, thiazide, and osmotic diuretics not recommended:
    
    • Dehydration may result in worsening toxicity
      
    • No direct effect on renal reabsorption because lithium is reabsorbed in proximal tubules
      
  • Kayexalate (sodium polystyrene sulfonate):
    
    • Animal and human studies indicate some efficacy
      
    • Complications may include hypokalemia, hyperkalemia, fluid overload, and dysrhythmias
      
  • Dialysis:
    
    • Peritoneal dialysis is not recommended
      
    • Hemodialysis may be recommended for augmenting elimination (see below)
      
• Hemodialysis is recommended for severe cases or acute ingestions with high levels indicating imminent toxicity:
  
  • Controversial indications (validated criteria yet to be established):
    
    • Severe and progressive neurologic abnormalities
      
    • Renal insufficiency
      
    • Altered mental status (e.g., placidly tolerating a rectal tube for GI effects would be considered substantial obtundation)
      
    • Ventricular dysrhythmia/cardiogenic shock
      
    • History of congestive heart failure or pulmonary edema
      
    • Acute ingestions with levels >4–5 mEq/L
      
    • Chronic ingestions with levels >2.5–3 mEq/L
      
  • Endpoint is lithium level <1 mEq/L
    
  • Repeat lithium level 6 hr after dialysis checking for evidence of redistribution
    
  • May need to repeat dialysis due to rebound effect (redistribution of intracellular lithium)
    
  • May reduce the potential for developing permanent neurologic sequelae with chronic toxicity
    

• Dextrose: D50 1 amp: 25 g (peds: D25W 4 mL/kg) IV
  
• Diazepam: 5 mg (peds: 0.2–0.4 mg/kg) IV q5min until seizures controlled
  
• Naloxone: 2 mg (peds: 0.1 mg/kg) IV or via endotracheal tube
  
• PEG solution: 2 L/hr (peds: 2 mL/kg/h) via nasogastric tube
  
• Thiamine: 100 mg IV
  

FOLLOW-UP

• Symptomatic
  
• Requiring hemodialysis
  
• Lithium level unchanged, increased, or >2 mEq/L despite ED intervention
  
• Moderate to severe symptoms with chronic levels >4 mEq/L warrant admission to ICU
  
• Intentional ingestion
  

Decreasing lithium levels every 2–4 hr in
asymptomatic
patient
and
serum lithium level <2 mEq/L (nonsuicidal patients)

Intentional overdose:

• Psychiatry consultation
  

Psychiatry follow-up to ensure correct dosing regimen in those with chronic poisoning

• Erroneously interpreting a predistribution lithium concentration as “toxic” in patients without symptoms or history of overdose
  
• Aggressive hydration in patients with pulmonary edema, renal insufficiency, or mental status changes
  

• Bailey B, McGuigan M. Comparison of patients hemodialyzed for lithium poisoning and those for whom dialysis was recommended by PCC but not done: What lesson can we learn?
  Clin Nephrol
  . 2000;54:388–392.
  
• Ghannoum M, Lavergne V, Yue CS, et al. Successful treatment of lithium toxicity with sodium polystyrene sulfonate: A retrospective cohort study.
  Clin Toxicol (Phila).
  2010;48:34–41.
  
• Mesquita J, Cepa S, Silva L, et al. Lithium neurotox-icity at normal serum levels.
  J Neuropsychiatry Clin Neurosci
  . 2010;22:451-p.e29–451.e29.
  
• Waring WS. Management of lithium toxicity.
  Toxicol Rev
  . 2006;25:221–230.
  

CODES

985.8 Toxic effect of other specified metals