Ulnar artery Doppler indices, a novel emerging predictor of segmental ulnar sparing after supraclavicular block: A...

Supraclavicular brachial plexus block offers several advantages over general anesthesia, yet segmental ulnar sparing is one of the procedure's key drawbacks. Many parameters were proposed to ascertain segmental ulnar sparing, including thermal imaging and perfusion index. However, none proved optimal; therefore, we aimed to evaluate ulnar artery Doppler indices as a potential predictor of segmental ulnar sparing.

This prospective observational study was conducted at a tertiary center. To obtain a study power of 90% and an alpha error of 0.05, a minimum sample size of 62 patients was required, with a minimum of 11 patients exhibiting segmental ulnar sparing. Adult patients who received supraclavicular brachial plexus block for hand surgery were included. Each dermatome was assessed in terms of motor and sensory function. An experienced operator performed Doppler examinations at baseline, 10-, 20-, and 30 min following block administration. The primary outcome was the accuracy of the change in PI (ΔPI) in predicting segmental ulnar sparing. Other outcomes included the change in resistive index (ΔRI) and the change in waveform morphology (ΔM) to predict segmental ulnar sparing.

Of the 81 patients assessed for eligibility, 15 were excluded, leaving sixty-six in the final analysis. Eleven of the 66 individuals showed segmental ulnar sparing. ΔPI and ΔRI have been identified as accurate predictors of segmental ulnar sparing with best cut-off values of <8.8% and 12%, respectively. Additionally, ulnar artery Doppler morphological changes from triphasic pattern to a monophasic wave can rule out segmental ulnar sparing with a 100% negative predictive value.

In adult patients undergoing hand surgery using supraclavicular brachial plexus block, Changes of Doppler indices, namely ΔPI, ΔRI, and ΔM, showed good accuracy in predicting segmental ulna preservation. However, the generalizability of our findings is limited by being a single-center study with a relatively small sample size.