Recommendations on the Use of Ultrasound Guidance for Adult Thoracentesis: A Position Statement of the Society of Hospital Medicine

9. We suggest that ultrasound can be used to evaluate normal lung sliding pre- and postprocedure to rule out pneumothorax.

Rationale: Normal lung sliding indicates normal apposition and movement of visceral and parietal pleura and rules out pneumothorax with a sensitivity that exceeds that of chest radiography, according to a meta-analysis of 20 studies using computed tomography or escape of intrapleural air at the time of drainage as the gold standard.⁶⁴ In this meta-analysis, the pooled sensitivity of ultrasound was reported to be 88% (85-91%) compared to 52% (49-55%) for radiography, although the analysis also suggests that the test characteristics are dependent on operator skill.⁶⁴ However, although lung sliding rules out pneumothorax, absence of lung sliding is not specific for pneumothorax and other conditions, including pleural adhesions, pleurodesis, and bronchial obstruction, can cause the absence of lung sliding.⁶⁴ Detection of a lung point conclusively rules in a pneumothorax.⁶⁵ Provided that the preprocedure lung ultrasound examination revealed normal lung sliding, a postprocedure examination can be performed to effectively evaluate for pneumothorax. This modality does not use ionizing radiation, is less expensive than computed tomography, can be performed faster than bedside chest radiography, and is more sensitive than supine or upright chest radiography.^64,66-71

10. We suggest avoiding delay or interval change in patient position between the time of marking the needle insertion site and performing the thoracentesis.

Rationale: Optimal patient positioning and ultrasound-guided site marking should be performed by the primary operator immediately before beginning an invasive procedure. Remote sonographic localization in which a radiologist marks a needle insertion site using ultrasound and the thoracentesis is performed at a later time by a different provider is an antiquated practice. Two early studies demonstrated that this practice is no safer than landmark-based thoracentesis.^6,72 One prospective study of 205 patients performed in 1986 showed no significant decrease in the incidence of complications from thoracentesis performed using remote sonographic localization versus landmark-based drainage.⁷² Complications in that study included a total of 22 pneumothoraces and 1 hematoma. The rate of complications in the group of patients who had site marking performed by radiology faculty and subsequent thoracentesis by medicine housestaff or attending physicians was 9.7% versus a complication rate of 12.7% in the landmark-based group.⁷² In addition, Raptopoulos et al. observed no significant difference in the pneumothorax rate between 106 patients with landmark-based thoracenteses and 48 patients who were sonographically marked by radiology faculty and then returned to the ward for completion of the thoracentesis by medicine housestaff (19% vs. 15%, respectively).⁶ Both groups had significantly higher rates of pneumothorax compared to those who underwent thoracentesis performed using real-time ultrasound guidance by radiology trainees (3%).⁶ The authors speculated that changing the patient’s position shifted the position of the pleural effusion, ultimately leading to the reliance on physical examination for the tap site.⁶

11. We recommend against performing routine postprocedure chest radiographs in patients who have undergone thoracentesis successfully with ultrasound guidance and are asymptomatic with normal lung sliding postprocedure.

Rationale: Chest radiography post-thoracentesis is unlikely to add information that changes management, especially if performed routinely, but does add expense, radiation, and inconvenience.⁷³ The most common serious complication of thoracentesis is pneumothorax, which is often accompanied by symptoms, particularly in those patients with pneumothorax large enough to warrant chest tube placement.^10,74,75 Pihlajamaa et al. retrospectively studied 264 ultrasound-guided thoracenteses performed by radiologists or radiology residents and noted that of 11 pneumothoraces, only 1 necessitated chest tube placement.¹⁰ Aleman et al. prospectively studied 506 ultrasound-guided and physical examination-guided thoracenteses and found that only 1% of asymptomatic patients developed a pneumothorax.⁷⁴ Eight of the 18 symptomatic patients required chest tube placement as opposed to 1 of the 488 asymptomatic patients.⁷⁴ A large prospective study of 941 ultrasound-guided thoracentesis reported that only 0.3% of asymptomatic patients with no suspicion of pneumothorax required tube thoracostomy.⁵ Postprocedure chest radiographs may be considered when thoracentesis is performed on mechanically ventilated patients, particularly when high airway pressures exist. In a study of 434 patients undergoing thoracentesis, only 10 patients had a pneumothorax (2.3%).¹¹ Six of these pneumothoraces occurred in 92 mechanically ventilated patients (6.5%), and 2 of these 6 patients required a chest tube.¹¹ None of the 4 spontaneously breathing patients with pneumothorax required a chest tube.¹¹

Training

12. We recommend that novices who use ultrasound guidance for thoracentesis should receive focused training in lung and pleural ultrasonography and hands-on practice in procedural technique.

Rationale: Healthcare providers have to gain various skills to safely perform ultrasound-guided thoracentesis independently. Trainees should learn how to use ultrasound to identify important structures (chest wall, ribs, lung, pleura, diaphragm, and subdiaphragmatic organs); detect pleural effusions with complex features, such as septations; identify consolidated lung tissue; and rule out a pneumothorax. Prospective studies done with novice learners have shown that focused training combining didactics and hands-on practice using simulation or live models improves skills to assess pleural effusions.^76-84 Several additional procedural techniques such as patient positioning and needle insertion are also important but are beyond the scope of these guidelines.