The procedure for removing fluid from the lung is thoracentesis, according to Johns Hopkins Medicine. During the procedure, a medical professional inserts a needle through the back chest wall into the space between the lung and the chest wall where fluid accumulates and draws off excess fluid.
During thoracentesis the patient sits and leans forward over a padded table, reports WebMD. An X-ray or ultrasound helps the doctor place the needle in the right place in some cases. A doctor or nurse cleans the skin on the test site, and an injection of a local anesthetic dulls sensation. Next the doctor inserts the needle. The patient may feel pressure or mild pain. A syringe or tube attached to a vacuum bottle draws off the fluid. The doctor removes the needle and covers the injection site.
Typically the area around the lungs only contains a small amount of fluid for lubrication allowing the lung to move to inhale and exhale easily, states Johns Hopkins Medicine. When extra fluid accumulates from infection or abnormal reabsorption, a condition called pleural effusion, breathing becomes difficult. Removing the excess fluid makes it easier to breathe and allows the doctor to test the fluid to find out the cause for the abnormality.