Pleural effusion is a common medical condition that usually results in the performance of thoracentesis to determine its etiology. Complications from thoracentesis may occur, and the more common ones include pain, pneumothorax, shortness of breath, vasovagal reaction, and cough. More serious complications from thoracentesis can occur but are less common. In most cases, thoracentesis is performed based on the results of physical examination or chest radiography. These, however, can be misleading.

A safer approach to this procedure is the use of ultrasound-guided thoracentesis. This technique allows for better identification of the pleural fluid and assists in ruling out other potential causes for the appearance of fluid on physical examination or radiography. Although the complication rates of bedside thoracentesis are well documented, the incidence of complications in the ultrasound-guided technique is less well documented. Jones and colleagues studied the incidence of complications from ultrasound-guided thoracentesis, evaluated the incidence of vasovagal events without the use of atropine before the procedure, and evaluated the factors that may lead to re-expansion pulmonary edema after the procedure.

The prospective, descriptive study involved patients at a tertiary referral hospital who were referred to interventional radiology for diagnostic or therapeutic ultrasound-guided thoracentesis. The decision to refer to radiology for ultrasound-guided thoracentesis was made by each patient's physician. Patient symptoms and complications from the procedure were recorded. The procedure was performed using ultrasonography to determine the location of the fluid and to guide the physician to where the pleural space should be entered. There was no limitation on the amount of fluid withdrawn, and the procedure ended when one of the following events occurred: no more fluid could be withdrawn, pain, excessive cough, vasovagal events, shortness of breath, or excessive bleeding at the entry site. Patients received pre- and post-procedure chest radiography. If a small pneumothorax was discovered, radiography was repeated every six to eight hours for 24 hours.

During the study period, 941 ultrasound-guided thoracentesis procedures were performed. Complication rates ranged from 0.2 percent for bleeding at the entry site to 2.7 percent for pain (see accompanying table). Only eight of the 24 patients with post-procedure pneumothorax received chest tubes to re-expand their lungs. If more than 1,100 mL of fluid was removed, the patients were much more likely to develop a pneumothorax that required a chest tube and to complain of pain during the procedure. The incidence of vasovagal reactions was low during the procedure, despite the fact that patients were not pre-medicated with atropine. In addition, the incidence of re-expansion edema was 0.2 percent, which occurred in patients who had more than 1,000 mL of fluid withdrawn.

The authors conclude that there are fewer complications of thoracentesis when the procedure is performed using ultrasound-guided technique than when using a non–image-guided technique. Premedication with atropine is not necessary given the low incidence of vasovagal reactions. In addition, re-expansion edema is unlikely to occur, even when more than 1,000 mL of pleural fluid is withdrawn.