<prompt> Highest incidence of pneumothorax occurs when branchial plexus is blocked by which routeInterscaleneSupraclavicularInfraclavicularAxillary  <response>: The incidence of pneumothorax may be as high as to 6 when brachial plexus is blocked through supraclavicular route but founately most of these pneumothorax resolve by themselves without treatment. Supraclavicular brachial plexus block: cellulitisabscess over the site of injection. Use caution in patients with poor pulmonary reserve, as a resultant pneumothorax may significantly worsen their respiratory status example: known pneumonia on the contralateral side ref Robbins 9e pg 456 