Comparing pulmonary ultrasound findings when viewing lung pleura beneath costal cartilage compared to costal bones

Objective

Ultrasound is one modality to quickly diagnose pneumothoraces in critically ill patients. The bones of the chest wall often produce shadowing that can make it difficult to visualize the lung pleura. We aim to compare the ease of identifying lung sliding when viewing the pleura beneath rib cartilage located closer to the sternum versus rib bone more laterally.

Methods

On five healthy models, bilateral lung ultrasounds were performed adjacent to the sternum over rib cartilage and laterally over rib bone. The linear transducer was placed in 3 locations at each rib level. Forty-five participants were enrolled into this study to report their level of confidence in identifying lung sliding using a five-point Likert scale. The Wilcoxon signed rank test was used for statistical calculations.

Results

The composite scores of lung sliding clarity were greater for images performed medially over costal cartilage compared to laterally over bone (3.5 vs 3.3, p = 0.02). When stratified by the location of cartilage or bone within the ultrasound image, lung sliding demonstrated greater clarity when the image was centered directly over cartilage versus bone (3.0 vs. 2.4, p < 0.01) and partially over cartilage versus bone, (3.4 vs 3.1, p < 0.01). No statistical difference was found when viewing images of lung sliding between cartilage versus bone (3.7 vs 3.7. p = 0.26).

Conclusion

Assessing lung sliding demonstrated greater clarity when performed medially over the rib cartilage versus laterally over rib bone when ribs were within the field of view. Clinicians should consider performing ultrasounds over rib cartilage when evaluating lung sliding pathology.