Thoracentesis in clinical practice.

Thoracentesis is a commonly performed procedure indicated for diagnostic and therapeutic purposes. Removal of pleural fluid should be performed by experienced operators and, when attempted by physicians-in-training, close supervision by credentialed individuals is necessary. Diagnostic thoracentesis is most valuable in separating exudates from transudates. Analysis of the exudative fluid has the highest yield when infection and malignancy is likely. Pneumothorax is the most common major complication and can be minimized by the use of small-gauge needles (no. 21 or no. 22) when a small amount of fluid is removed (35 to 50 ml). Patients who may pose difficulties (e.g., those receiving ventilator support) appear to have no greater morbidity with thoracentesis than those patients not ventilator dependent. Ultrasound may be of value to decrease morbidity when small or loculated volumes of fluid are present. Therapeutic thoracentesis offers relief of symptoms of dyspnea, but caution is particularly needed because large needles and large volumes of fluid removed may increase morbidity.