The difference of subcutaneous digital nerve block method efficacy according to injection location

Area of Science:

• Emergency Medicine
• Anesthesiology
• Hand Surgery

Background:

• Digital nerve blocks are crucial for managing finger injuries in emergency departments.
• Subcutaneous injection is a common technique for digital nerve blocks.

Purpose of the Study:

• To compare the efficacy of subcutaneous digital nerve blocks at different injection sites.
• To evaluate the time to anesthesia and pain levels associated with metacarpophalangeal (MCP) versus proximal interphalangeal (PIP) joint injections.

Main Methods:

• A simulation study involving medical students.
• Comparison of lidocaine injection at the volar side of the MCP joint versus the PIP joint.
• Measurement of time to anesthesia, pain (Numeric Rating Scale), injection site characteristics, and correlation with outcomes.

Main Results:

• The proximal interphalangeal (PIP) joint group achieved anesthesia significantly faster (2.55 min) than the metacarpophalangeal (MCP) joint group (3.79 min).
• Pain levels (NRS median 4) were comparable between the PIP and MCP joint injection groups.
• Injection site length and circumference varied between groups, with length correlating to time to anesthesia.

Conclusions:

• Subcutaneous injection at the proximal interphalangeal (PIP) joint offers a faster onset of anesthesia compared to the metacarpophalangeal (MCP) joint for digital nerve blocks.
• Both injection sites provide comparable pain relief, suggesting PIP joint injections may be more efficient.