Spinal 2-chloroprocaine: minimum effective dose

Area of Science:

• Anesthesiology
• Pharmacology

Background:

• Preservative-free 2-chloroprocaine (2-CP) is a short-acting spinal anesthetic.
• Previous studies established efficacy in the 30-60 mg range.
• Lower dose effects were previously uninvestigated.

Purpose of the Study:

• Determine the minimum effective dose of spinal 2-CP for anesthesia.
• Characterize the dose-response relationship of spinal 2-CP.
• Compare low doses (10, 20 mg) with established higher doses (30-60 mg).

Main Methods:

• Randomized, double-blind, crossover study design.
• Involved 8 volunteers receiving spinal 2-CP at 10 mg and 20 mg.
• Compared results with prior data for 30-60 mg doses.

Main Results:

• Sensory and motor block characteristics, including peak height and regression times, increased with doses from 10 to 60 mg (P <.0001).
• Tolerance to tourniquet and response to electrical stimulation improved with higher doses.
• No significant difference in motor block was observed between 20 mg and 30 mg, or between 40 mg and 60 mg.

Conclusions:

• Spinal 2-CP at 40 mg and 60 mg ensures rapid, dependable sensory and motor blockade.
• Doses of 20 mg and 30 mg provide adequate sensory anesthesia for short procedures but with reduced motor block and potential sacral sparing.
• The 10 mg dose is considered ineffective due to brief and inconsistent sensory anesthesia.