Use of colour Doppler sonography for quantitation of the changes in the blood flow following axillary plexus block

The axillary brachial plexus block is a well-known technique for intra- and postoperative analgesia and sympathetic blockade in hand and microsurgery. The aim of this study was to show the influence of the axillary brachial plexus block on the blood flow as a side effect. Methods. We used a colour-coded sonography unit (Toshiba) with a 7.5-MHz transducer. A total of 12 patients with no clinical signs of vascular diseases were enrolled in this study. We measured the peak blood flow velocity and the peak flow at the bifurcation of the brachial artery and vein and the proximal and distal radial artery before and after the plexus block. In addition, we were able to take the morphological aspects of the analysed vessels into consideration as we also used conventional sonography. This was done to detect any early signs of vascular malformation or arteriosclerosis, either of which might have affected the measurements. Results. The average arterial peak blood flow after the plexus block was 1.9 times that before. On the venous side, the block effect caused an average increase of the blood flow to 8.6 times than before the block. In general, an additional and immediate effect of the block was a significant rise in blood flow velocity with an increase in cross-section area. Conclusions. The brachial plexus block combines two advantages: pain relief and pain management plus temporary sympathectomy. In conclusion, it prevents vasospasms and improves the circulation of the hand in patients undergoing reimplantation of limbs and those with nutritional disorders.