Anesthesia Considerations 

Lithium Toxicity  

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Background 

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• Exact toxic dose not known, but an adult who ingests more than 2400 mg or child who ingests more than 30 mg/kg requires assessment for toxicity

• Types of toxicity:

  • Acute toxicity:  Lithium overdose in a patient who does not regularly take lithium.  Mostly present with GI symptoms of Gastrointestinal symptoms of nausea, vomiting, and diarrhea.  Neurologic symptoms are delayed.

  • Acute-on-chronic toxicity: Acute overdose in a patient who takes lithium daily.  A sudden decline in renal function in a patient taking lithium can also lead to acute-on-chronic toxicity.

  • Chronic toxicity: The history generally involves a patient on chronic lithium therapy who, due to toxic drug effects, physical disability, or concurrent illness, becomes hypovolemic, leading to reduced renal excretion of lithium. Alternatively, toxicity can develop solely from the effects of medications that reduce kidney function.  These patients present with early and predominate neurologic signs and symptoms (eg, agitation, confusion, slurred speech) . There are also the complications from chronic use (eg, neuromuscular irritability, tremor).

• Lithium prolongs both depolarizing and non-depolarizing neuromuscular blockade

• Lithium may affect the electrocardiogram, including T wave flattening/inversion and QRS widening. 

• Lithium can cause conduction blocks

 

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Considerations 

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• Potential cardiopulmonary instability requiring resuscitation

• Potential hypovolemia and electrolyte imbalances (esp. Sodium) 

• Potential neurologic dysfunction and seizures

• Anesthesia-specific concerns of lithium

  • Prolonged duration of muscle relaxants

  • Association with conduction defects and ST changes on ECG

 

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Management

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• Consult toxicology, poison control, and nephrology

• Ensure stable airway, breathing, and circulation

• Manage seizures with benzodiazepines

• Ensure normal volume status and sodium levels

  • Lithium can cause nephrogenic diabetes insipidus

• Consider GI decontamination within 1 hour of ingestion of instant release lithium or within 4 hours of ingestion of sustained-release lithium

• Consult nephrology for hemodialysis for the following indications:

  • Symptoms of severe lithium toxicity at any serum levels (eg, seizures, altered mental status, hypotension that does not resolve quickly with IV fluids, rigidity, hypertonicity, myoclonus, cardiopulmonary collapse, or life-threatening dysrhythmia)

  • Serum lithium concentration >4 mEq/L (4 mmol/L) in patient with impaired kidney function (eGFR <45 mL/min)

  • Serum lithium concentration >5 mEq/L (or 5 mmol/L)

 

References 

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• Simon Flood, MRCP FRCA, Andrew Bodenham, FRCA, Lithium: mimicry, mania, and muscle relaxants, Continuing Education in Anaesthesia Critical Care & Pain, Volume 10, Issue 3, June 2010, Pages 77–80

• Hedya SA, Avula A, Swoboda HD. Lithium Toxicity. [Updated 2022 Jun 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK499992/