Ultrasound is better than injection pressure monitoring detecting the low-volume intraneural injection.

Inadvertent intraneural injection is not infrequent during peripheral nerve blocks. For this reason, injection pressure monitoring has been suggested as a safeguard method that warns the clinician of a potentially hazardous needle tip location. However, doubts remain whether it is superior to the sonographic nerve swelling in terms of earlier detection of the intraneural injection. An observational cadaveric study was designed to assess injection pressures during an ultrasound-guided intraneural injection of the median nerve. We hypothesized that the evidence of nerve swelling occurred 31 injections were considered for analysis (two were excluded due to uncertainty regarding needle tip position). >15 pound per square inch was reached in six injections (19%) following a median injected volume of 0.6 mL. Nerve swelling was evident in all 31 injections (100%) with a median injected volume of 0.4 mL. On dissection, spread location was confirmed intraneural in all injections. Ultrasound is a more sensitive and earlier indicator of the low-volume intraneural injection than injection pressure monitoring.

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© American Society of Regional Anesthesia & Pain Medicine 2022. No commercial re-use. See rights and permissions. Published by BMJ.

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Competing interests: None declared.