Interscalene brachial plexus block. Effects on pulmonary function.

Background And Objectives: The interscalene is one of the most common approaches used in brachial plexus block. However, the association of this approach with the ipsilateral blockade of the phrenic nerve has been demonstrated. The resulting diaphragmatic dysfunction causes changes in lung mechanics, which can be potentially deleterious in patients with limited respiratory reserve.