Lumbar plexus block using high-pressure injection leads to contralateral and epidural spread

Area of Science:

• Anesthesiology
• Regional Anesthesia
• Pain Management

Background:

• Lumbar plexus block offers unilateral anesthesia, but bilateral spread occurs in up to 27% of cases, reducing predictability.
• High injection pressures during lumbar plexus block are hypothesized to increase the risk of bilateral or neuraxial anesthesia.

Purpose of the Study:

• To investigate the association between injection pressure during lumbar plexus block and the occurrence of bilateral or neuraxial anesthesia.

Main Methods:

• Eighty patients (ASA I-II, 18-65 years) undergoing knee arthroscopy received a standard nerve stimulator-guided lumbar plexus block with 35 ml 1.5% mepivacaine.
• Patients were randomized to low-pressure (<15 psi) or high-pressure (>20 psi) injection groups, monitored by an inline pressure monitor.
• Block success and bilateral sensory/motor blockade were assessed.

Main Results:

• The study was terminated early due to a high incidence of neuraxial spread in the high-pressure group.
• 50% of patients in the high-pressure group experienced neuraxial block (T10 or higher), compared to 0% in the low-pressure group.
• 60% of the high-pressure group showed bilateral femoral sensory blockade, versus 0% in the low-pressure group.

Conclusions:

• High injection pressure (>20 psi) during lumbar plexus block frequently leads to unintended bilateral blockade.
• High injection pressure is associated with a significant risk of neuraxial blockade, compromising the unilateral advantage of lumbar plexus block.