Validity of pleural sliding sign in patients on controlled mechanical ventilation

Abstract

Background Pneumothorax, a frequent complication of mechanical ventilation, is usually small to identify in the portable radiograph. Sliding sign on lung ultrasound (US) is currently the most frequently used method to rule out subtle pneumothorax in this case. Aim To evaluate the cogency of using the lung sliding sign as a diagnostic sign for the absence of pneumothorax in patients on controlled mechanical ventilation and compare between high-frequency and low-frequency transducers. Patients and methods A prospective study conducted on mechanically ventilated patients was conducted. Chest radiograph and US were done. US findings were recorded using both high-frequency and low-frequency transducers in different spaces and lines using the B-mode and M-mode to detect the best area to see the sliding sign and seashore sign clearly. Results This study included 36 patients with a mean±SD age of 56.44±17.37 years. The linear probe showed the highest sensitivity (100%) to detect the lung sliding sign with no false-negative results in which the lung sliding amplitude varies across the intercostal spaces with greater in the base (47.20% in the sixth space) than the apex (third space). The curved probe, when used to detect the lung sliding sign, showed a sensitivity of 84.6% leaving only two false-negative cases. Conclusion The curved probe can be used during the routine chest US examination in mechanically ventilated patients; however, the linear probe, which is the preferred choice for examining the pleura, can be spared for doubtful cases whenever US signs were missed.

Keywords

• lung sliding
• mechanical ventilation
• pneumothorax
• ultrasound