This document discusses techniques for sampling and processing pleural fluid. It describes how to prepare patients, collect pleural fluid samples, and divide samples into different tubes for various tests and storage. The key steps are: 1. Collect pleural fluid using sterile technique by inserting a catheter into the pleural space and aspirating fluid. 2. Divide the fluid among several tubes - one with EDTA for cell counts, one with heparin for blood gas analysis, one with heparin for chemistry tests, one sterile heparin tube for culture, and one with heparin for cytology. 3. Label samples with patient information, date, tests needed, and store appropriately - analyzing blood gas