Objective

To determine if the use of a "needle enhancing software" installed in ultrasound machine would facilitate learning process of peripheral nerve blocks. Our hypothesis is that inexperienced veterinary surgeons would be more successful using this new software, so the learning curve would be steeper.

Materials and Methods

This blinded, randomized and prospective study was performed after the ethics committee approval was obtained (URN 2011 1109).

Eight hind limbs from canine cadavers were divided into two groups; SOFTWARE ON (G-I) and SOFTWARE OFF (G-II). Eight anaesthetists with no previous experience with ultrasound-guided regional anaesthesia were recruited. Thirty-six procedures were carried out (eighteen each group).

Once the sciatic nerve was visualised by ultrasonography, the anaesthetist introduced a needle and it was guided by sonography. When tip of the needle was considered to be close to the nerve, 0.05 ml of methylene blue dye was injected. Finally, dissection of the sciatic nerve was performed.

Parameters evaluated were number of attempts to see the needle with ultrasonography, time spent to perform the technique, subjective evaluation regarding needle visualisation and the position of the tip of the needle in relation to the nerve, and relationship between the dye and the sciatic nerve during its dissection.

Statistical analysis was performed using PASW version 18.0. Chi-squared and Mann-Whitney U tests were used depending on the data (categorical or numerical). Differences were considered significant when p < 0.05.

Results

No significant differences between groups were observed regarding the time to perform the procedure (G-I: median 25.5, IQR: 18.4–44.3 seconds versus G-II: median 35.7, IQR: 18.6-78.72 seconds), subjective evaluation of the needle visualization and distance between the tip of the needle and the nerve in the ultrasound screen.

Significant differences between groups were found regarding the number of attempts (G-I: median 1, IQR: 1–1 attempts versus G-II: median 1, IQR: 1–4 attempts), and the proximity of the dye to the nerve during hind limb dissection (G-I: 72.2% versus G-II 16.6%)

Conclusions

This study showed a higher success rate in sciatic nerve staining when anaesthetists worked with the needle enhancing software. Our findings suggest the use of this technology would improve the precision of this technical procedure and would positively influence the learning process of ultrasound-guided peripheral nerve blocks in the dog.

Visualisation of the needle with the “needle enhancing software” turned on and off. Both pictures were taken at the same moment.