Vertical infraclavicular block of the brachial plexus: effects on hemidiaphragmatic movement and ventilatory function

Several case reports have suggested that block of the brachial plexus by the vertical infraclavicular approach influences hemidiaphragmatic movement and ventilatory function. These effects have not been evaluated in a prospective study.

Thirty-five consecutive patients scheduled for elective surgery under brachial plexus anesthesia were included. A vertical infraclavicular block was performed with ropivacaine 0.75%, 0.5 mL/kg. Ipsilateral hemidiaphragmatic movement was measured by ultrasonography at maximal forced inspiration and sniff. Forced vital capacity (FVC) and forced expiratory volume (FEV(1)) were measured by a portable vitalograph. All measurements were performed before the block procedure and at 5, 10, 30, and 60 minutes after the block.

The block was successful in 34 of 35 patients. In 9 patients (26%), a change in hemidiaphragmatic movement (reduced or paradoxical) was observed. A significant decrease in ventilatory function was found in 8 of these 9 patients between baseline and at 60 minutes: FVC = -0.8 +/- 0.4 L and FEV(1) = -0.7 +/- 0.3 L, mean +/- SD (relative decrease: FVC = 30 +/- 14% and FEV(1) = 32 +/- 13%, mean +/- SD). Horner's syndrome was seen in 4 patients (12%), and in all, a change in hemidiaphragmatic movement was observed. No clinical signs of ventilatory dysfunction were noticed.

The vertical infraclavicular block can result in a change in ipsilateral hemidiaphragmatic movement, with a decrease of ventilatory function. Although a correlation between the presence of Horner's syndrome and hemidiaphragmatic dysfunction was observed, hemidiaphragmatic dysfunction also occurred independently.