Identification of lung sliding: a basic ultrasound technique with a steep learning curve

Introduction. One of the basic premises of sonographic lung imaging is the concept of lung sliding. Identification of clear lung sliding excludes pneumothorax (PTx) at that specific local point.

Methods. Fifty-seven 4th year medical students were given a 20-minute lecture on sonographic identification of lung sliding and exclusion of PTx. After the lecture, students were asked to correctly position the probe, identify shown structures and on each attempt (six attempts in a row) state whether lung sliding is present or not.

Results. There were 57 students in the sample. Fifty students (87.7%) successfully positioned the probe (all 4 positions) for PTx identification. All but five students (91.2%) recognized the anatomic structures of the thorax. Mean number of correctly identified cases per student was 5.1 ± 1.1. In 292 (85.4%) cases, the answer was correct. In 298 (87.1%) cases, students were confident in the correct answer. Students who were confident in the right answer gave the right answer significantly more often when compared to others (90.3% vs. 52.3%, p < 0.001). Sensitivity of this method for 4th year medical students was 82.6% and its specificity was 87.9%. For correct identification of lung sliding in the sixth attempt, students on average needed 4.5 correct attempts.

Conclusion. Our study suggests that 4th year medical students with no prior experience in lung ultrasonography can easily acquire knowledge and skills needed to detect thoracic wall structures and identify lung sliding with a high degree of sensitivity and specificity. 

medical students, ultra-sonography, pneumothorax

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