Partial Air Replacement During Thoracentesis: Its Value in Diagnosis and Treatment

Partial replacement of fluid withdrawn on thoracentesis allows one to withdraw large amounts of fluid at one time without upsetting the patient, because changes in intrapleural pressure are so little. It also causes fluid covering the lung to fall from it, and thus allows the x-ray visualization of the surface of the lung and of the parietal pleura. This procedure should be used in all cases of pleural effusion, but where there is an empyema on hemothorax, it is important not to allow any air to remain in the pleural cavity. The air is allowed to enter the pleural cavity freely through the needle in the chest wall when the syringe is disconnected from it. If a needle of size 15 or smaller is used it is not necessary to measure the amount of air.