Spirometry, blood gas analysis and ultrasonography of the diaphragm after Winnie's interscalene brachial plexus block.

Ten patients with healthy lungs were subjected to radiology, sonography, spirometry and blood gas analysis before and after an interscalene brachial plexus block prior to shoulder surgery. Winnie's interscalene block induced ipsilateral hemidiaphragmatic paresis that was confirmed by radiology and sonography. Changes in forced expiratory vital capacity (FVC), forced expiratory volume (FEV1) and peak expiratory flow rate (PEFR) were significant and PaO2 declined by an average of 1.3 kPa. These changes should not cause further clinical symptoms in sitting patients with unaffected lungs. In patients with pulmonary disease, this method of nerve block should be limited to cases for which there is a clear indication.