[Brachial plexus block. Effect of low interscalenic approach on phrenic nerve paresis]

The aim of the paper was to determine the influence of the brachial plexus block on phrenic nerves paralysis in distal side of interscalenic space (between 1/3 medium and 1/3 inferior), with little volume of local anesthetic drug. Comparative, prospective, randomized study.

Fourty-three patients, ASA I-II, submitted to surgical operation at superior arm, shoulder excluded. The patients were randomized into two groups: group A, 21 patients, were submitted to brachial plexus block by armpit tract; group B, 22 patients, were submitted to brachial plexus block by low interscalenic tract. Ropivacaine 0.75%, 20 ml, was used as local anesthetic. Plexus was localized by ENS and isolated needles 25 G-35 mm or 22 G-50 mm.

respiratory disease. Effects of phrenic nerves paralysis were evaluated by mean measures of FEV1, FVC, and PEF, with sitting patients, before and after 30 min of the nerve block. Other parameters we obtained were NIBP, CF, ECG, and SaO2.

In the B group FVC, FEV1 and PEF, after brachial plexus anesthesia, diminished of 19.39%, 20.8% and 20.7% respectively in comparison with the same parameters measured before local anesthesia. No patients had dyspnea. In group A significant modifications of respiratory parameters were not recorded. Both groups showed stability of cardiocirculatory findings.

Brachial plexus anesthesia by low interscalenic tract, even using little local anesthetic drug volumes, like other supraclavear block techniques determines ipsilateral diaphragm paralysis.