Lithium: Anesthetic Considerations

Overview and Pharmacology

Core Pharmacology and Therapeutic Monitoring

• Lithium is a mood stabilizer used primarily for bipolar disorder and related conditions.^1,3
• Lithium is not protein bound and is not metabolized; it is cleared almost entirely by the kidney through filtration and proximal tubular reabsorption.³
• Serum concentrations are monitored because of a narrow therapeutic index; a typical maintenance target is approximately 0.6–1.2 mmol/L, but clinical status is more important than any single level.^1,3
• Conditions that decrease effective circulating volume or sodium (e.g., dehydration, diuretics, gastrointestinal losses) increase lithium reabsorption and can raise serum concentrations.^3,4
• The elimination half-life is variable (often ~24 hours) and is prolonged in older adults, chronic therapy, and renal impairment; this variability underlies differing recommendations on preoperative discontinuation timing.^1,3,5

Cardiac and Neurologic Effects Relevant to Anesthesia

• Neurologic findings of toxicity range from tremor and ataxia to confusion, dysarthria, and seizures; chronic toxicity may present predominantly with neurologic symptoms.³
• Cardiac manifestations include bradycardia, sinus node dysfunction, atrioventricular conduction abnormalities, and repolarization changes on electrocardiogram.⁶
• Because lithium effects overlap with common anesthetic adverse effects (sedation, hypotension, neuromuscular weakness), baseline symptoms and recent dose changes should be elicited during preoperative evaluation.^1,3

Perioperative Management and Anesthetic Interactions

Preoperative Planning and Medication Management

• Procedure-related risk and patient factors (renal function, age, and anticipated fluid shifts) should be assessed when deciding whether to continue lithium therapy.
• Urea/creatinine, electrolytes, and an electrocardiogram (ECG) should be reviewed or obtained if not recently available; a lithium level is reasonable if adherence is uncertain or symptoms suggest toxicity.²
• For minor surgery in stable patients, some guidance supports continuing lithium with close monitoring.²
• For major surgery or when significant hemodynamic instability is anticipated, lithium is commonly withheld; recommendations range from 24 hours to 72 hours preoperatively, depending on renal risk and half-life variability.^1,2
• Medications that increase lithium concentrations (e.g., nonsteroidal anti-inflammatory drugs, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, and thiazide diuretics) should be avoided when feasible, or used with enhanced monitoring and dose adjustment.⁴
• Euvolemia and sodium balance should be maintained; patients with lithium-associated nephrogenic diabetes insipidus may be prone to perioperative polyuria and hypernatremia.³

Intraoperative Anesthetic Interactions

• Minimum alveolar concentration and sedative requirements may be reduced; anesthetic agents should be titrated to clinical effect, and processed electroencephalography (EEG) monitoring may be considered when appropriate.¹
• Hypotension and bradycardia may be more pronounced in susceptible patients (e.g., older adults, dehydration, conduction disease); intravascular volume should be optimized and vasoactive drugs titrated to response.^1,6

Neuromuscular Blockade and Reversal

• Lithium can potentiate depolarizing neuromuscular blockade; prolonged succinylcholine effect has been described.⁷
• Lithium can also potentiate nondepolarizing blockade; prolonged recovery has been reported with rocuronium and other agents.⁸
• Lower neuromuscular blocker dosing and quantitative monitoring (e.g., train-of-four ratio) are recommended to avoid residual weakness.¹

Regional and Neuraxial Anesthesia Considerations

• Prolonged peripheral nerve blockade after local anesthetic administration has been reported in patients on chronic lithium; careful counseling and follow-up are reasonable when long-acting local anesthetics or continuous catheters are used.⁹
• If neuraxial anesthesia is planned, hemodynamic effects should be anticipated and treated in the usual manner; coexisting psychotropic medications (e.g., antipsychotics) may have additive hypotensive effects.¹

Postoperative Monitoring and Restarting Lithium

• Renal function and electrolytes should be reassessed after major surgery or critical illness, particularly if polyuria, hypernatremia, or neurologic changes occur.^3,10
• Lithium can be restarted when the patient is hemodynamically stable, euvolemic, and tolerating oral intake, and when renal function has returned to baseline or is clearly stable.²

Lithium Toxicity and Management

Recognition and Initial Evaluation

• Lithium toxicity may be precipitated perioperatively by dehydration, reduced glomerular filtration, and interacting medications; presentations can be subtle and overlap with anesthetic effects.^3,10
• Symptoms often include gastrointestinal upset, tremor, ataxia, dysarthria, confusion, and somnolence; severe toxicity can progress to seizures, coma, and respiratory failure.³
• Electrocardiographic changes and dysrhythmias can occur, including bradycardia and conduction abnormalities; an ECG should be obtained when toxicity is suspected.⁶
• The initial evaluation should include serum lithium concentration (if available), a basic metabolic panel, glucose, osmolality, and an assessment of volume status.^3,5

Treatment Priorities

• Lithium should be discontinued immediately, and supportive care initiated, with attention to airway protection, seizure management, and temperature control.³
• Isotonic intravenous fluids should be used to correct hypovolemia and promote renal clearance; electrolyte abnormalities (particularly sodium) should be corrected carefully.³
• Nephrotoxic or lithium-raising medications should be discontinued when possible, and urine output and neurologic status should be monitored closely.^3,4

When to Consider Hemodialysis

• The EXTRIP Workgroup recommends extracorporeal treatment for severe lithium poisoning, including when kidney function is impaired and the lithium concentration exceeds 4.0 mEq/L or when decreased consciousness, seizures, or life-threatening dysrhythmias are present regardless of the lithium concentration.⁵
• Extracorporeal treatment is suggested when the lithium concentration exceeds 5.0 mEq/L, when significant confusion is present, or when the projected time to reduce the lithium concentration below 1.0 mEq/L exceeds 36 hours.⁵
• Hemodialysis is preferred; ongoing monitoring for rebound lithium levels after dialysis is important because of redistribution from tissues.5