Steps of the Procedure The selection of site, preparation and anesthetic principles are the same as for thoracentesis. Be sure to anesthetize the parietal pleura well. If not, it will be very painful. The thoracentesis kit does not have a sufficient amount of anesthetic for the purposes of a pleural biopsy. I usually use 6-8 cc's of 2% xylocaine to anesthetize the selected site.