What is the most important instruction to give a client undergoing thoracentesis?

The most important instruction for a client undergoing thoracentesis is to avoid any movement or coughing. This is crucial because thoracentesis involves the insertion of a needle into the pleural space to remove excess fluid. Any movement or coughing can alter the position of the needle, which increases the risk of complications such as a punctured lung (pneumothorax) or damage to surrounding tissues and organs. Maintaining stillness ensures that the procedure is performed safely and effectively, minimizing risks and allowing for precise placement of the needle.

In this context, deep breathing during the procedure might be beneficial for relaxation, but it can also lead to unintended movement. Drinking plenty of water before the procedure is generally not advised, as it may lead to aspiration risk during the procedure, particularly since the thoracentesis is performed when the patient is often in a sitting position and may not be comfortable to drink. Raising the legs is typically not relevant to the procedure itself and does not address the immediate needs during thoracentesis.