Chest
Original ResearchChest UltrasonographyThe Dynamic Air Bronchogram: A Lung Ultrasound Sign of Alveolar Consolidation Ruling Out Atelectasis
Section snippets
Patients
Over a 6-year period, we prospectively studied patients who were critically ill, using the following selection criteria: admitted to a medical ICU, mechanically ventilated, having a suspected (by the managing team, blinded to the ultrasound results) pneumonia or resorptive atelectasis, receiving fibroscopy (ordered at the discretion of the managing team) that showed either an obstacle confirming the resorptive atelectasis (atelectasis group) or a satisfactory airway patency plus positive
Results
In the pneumonia group, ultrasound patterns of alveolar consolidation were located in the right lung in 34 patients, the left lung in 14 patients, and bilaterally in 4 patients. In the atelectasis group, they were located to the right in 4 patients and to the left in 12 patients. In the pneumonia group, a dynamic air bronchogram was observed in 32 patients and a static air bronchogram in 20 patients. In the atelectasis group, a dynamic air bronchogram was observed in 1 patient, and a static air
Discussion
The potential for an ultrasound to distinguish pneumonia from resorptive atelectasis comes first from its ability to document alveolar consolidation. In 98.5% of the patients, acute alveolar consolidations abutted the visceral pleura, creating the mandatory acoustic window for their ultrasound demonstration.5
In this study where all patients were mechanically ventilated, respiratory movement of gas bubbles within the bronchi indicate preserved patency of the airways because the gas bubbles are
Conclusions
In patients with ultrasound-visible alveolar consolidation displaying air bronchograms, the dynamic air bronchogram had a 94% specificity and a 97% positive predictive value for diagnosing pneumonia and distinguishing it from resorptive atelectasis. Static air bronchograms were seen in most resorptive atelectases and in one third of patients with pneumonia. Associated with the clinical data, this finding allows for a better understanding of the pathophysiology of lung diseases and, in some
Acknowledgment
The authors thank François Jardin for his trust.
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