Duration of Intravenous Lidocaine Infusion
The duration of IV lidocaine infusion should not generally exceed 24 hours for postoperative pain management. 1
Standard Duration Protocol
Maximum initial duration is 24 hours for most postoperative patients, as this timeframe is typically sufficient since postoperative pain decreases with time and other analgesics remain available 1
Most patients do not benefit from prolonged infusion beyond 24 hours, though exceptions exist for patients with chronic pain 1
Extension Beyond 24 Hours
If extending the infusion beyond 24 hours becomes necessary:
Decision must be made by a consultant anaesthetist or intensivist and/or the acute pain team, within the scope of relevant hospital guidelines 1
Infusion rate must be reduced to 50% of the original rate when extending beyond 24 hours 1
This dose reduction is critical because lidocaine exhibits time-dependent pharmacokinetics after 12 hours of infusion, with the elimination half-life prolonging from approximately 100 minutes to 3.22 hours after 24 hours 1
Pharmacokinetic Rationale
The duration limitation is based on important pharmacokinetic changes:
Lidocaine pharmacokinetics are linear and predictable only up to 12 hours of continuous infusion 1
After prolonged infusion (>24 hours), the elimination half-life can be prolonged two-fold or more, particularly in patients with liver dysfunction 2
The typical elimination half-life is 1.5 to 2.0 hours following bolus injection, but this changes significantly with continuous infusion 2
Critical Safety Considerations
Lipid emulsion 20% must be readily available wherever IV lidocaine is used throughout the infusion duration 1, 3
Patients should ideally be managed in a monitored bedspace (high dependency unit/level 2 care) outside the operating theatre/recovery room 1
Monitoring frequency: Every 15 minutes for the first hour, then hourly as minimum thereafter 1
Early signs of toxicity include peri-oral tingling, tinnitus, light-headedness, and restlessness—these neurological symptoms appear before cardiovascular changes 1