Lidocaine plasma concentrations during and after endoscopic procedures

Area of Science:

• Anesthesiology
• Pharmacology
• Gastroenterology

Background:

• Lidocaine is a commonly used local anesthetic.
• Assessing safe dosage ranges for topical lidocaine in endoscopic procedures is crucial for patient safety.

Purpose of the Study:

• To determine plasma lidocaine concentrations and safety profiles in patients undergoing upper gastrointestinal endoscopy and bronchoscopy.
• To establish safe dosing guidelines for topical lidocaine in these procedures.

Main Methods:

• Plasma lidocaine concentrations were measured in patients undergoing upper gastrointestinal endoscopy (n=8) and bronchoscopy (n=12).
• Peak concentrations and time to peak were recorded.
• Safety was evaluated based on established toxic concentration thresholds.

Main Results:

• Highest plasma lidocaine concentrations were 0.98 µg/ml (GI endoscopy) and 3.79 µg/ml (bronchoscopy).
• Peak concentrations occurred at 15 minutes (GI endoscopy) and 30-60 minutes (bronchoscopy).
• Observed concentrations remained below the toxic threshold of 6 µg/ml.

Conclusions:

• Topical lidocaine doses up to 16 mg/kg are safe for endoscopic procedures in patients with normal hepatic and cardiovascular function.
• Patients with liver metastases are at high risk for lidocaine toxicity, even with normal liver function tests.
• High-risk patients require lower doses and extended post-procedure monitoring (≥60 minutes).