Stimulating needle to nerve distance correlation with electric current during regional anesthesia

Aim: To find out if we can predict the needle - nerve distances during regional anesthesia by stimulating tibial and common peroneal nerves with electric impulses, which have certain characteristics. Objectives: To investigate if needle – nerve distances differs between different nerves and between sexes during peripheral nerve stimulation. To determine whether proper distribution of local anesthetic around the nerves depends on needle – nerve distance during peripheral nerve stimulation. Methods: Tibial and common peroneal nerves were stimulated with 0.2 – 0.5 mA electrical current during regional anesthesia with peripheral nerve stimulator. After the motor response the needle – nerve distances were measured with ultrasound. Local anesthetic was then injected and it was observed whether it distributed properly around the nerves. The data was calculated using the “IBM SPSS Statistics 20” program, linear regression model was applied. Research Participants: Adult patients who needed tibial and common peroneal nerves blockade during, corresponding to ASA I-II class. Excluding criteria were any muscle – nerve diseases, diabetes mellitus, coagulopathies and allergies to local anesthetics. Results: A total of 42 patients participated in the study including 17 (41.5%) men and 24 (58.5%) women. The mean distance between needle and tibial nerve was 0.95 (0.1 - 2.2) mm and between needle and common peroneal nerve was 1.05 (0.1 - 2.2) mm. The difference between these distances was not statistically significant at p >0.05. The average distance between the needle and tibial nerve among men was 1.135 (0.858 – 1.413) mm, and among women was 0.817 (0.6 – 1.033) mm. Meanwhile, the average distance between the needle and common peroneal nerve among males was 1.124 (0.95 – 1.49) mm and among women was 0.929 (0.69 – 1.16) mm. Although in both cases the needle - nerve distance was ~ 0.3cm shorter among women this difference was not significant p >0.05. The injected local anesthetic distributed properly in 32 (78%) cases. In case of inadequate distribution (compared to sufficient) tibial nerve was 0.45 (SD 0.20) mm and common peroneal nerve was 0.63 (SD 0.19) mm too far from the needle. In both cases this was a significant difference at p