Sonography of the normal lung: Comparison between young and elderly subjects

Background The senile lung undergoes physiologic changes that are well known but have not been investigated with ultrasound (US). Thus, the aim of our study was to compare the US appearances of the lungs in a group of healthy, nonsmoker elderly subjects with those in a group of young subjects. Methods One hundred elderly subjects older than 65 years of age (mean age ± SD, 79 ± 7 years) and 50 younger subjects less than 56 years of age (mean age ± SD, 33 ± 12) underwent US examination of the lungs. We analyzed the anterior, midlateral, and posterobasal surface of each lung to evaluate the presence or absence of A‐lines and B‐lines. Fisher's exact test and Pearson's χ2 test were used to compare the findings in the two groups. Results A‐lines were absent in 94/100 (94%) elderly subjects versus 2/50 (4%) young subjects (p  < 0.0001). B‐lines were found in 37/100 (37%) elderly subjects: ≤3 lines per field of view in 27/37 (73%); >3 lines in 2/37 (5%); both ≤3 lines and >3 lines (depending on the region scanned) in 8/37 (22%). In contrast, only in 5/50 (10%) young subjects were B‐lines visible (≤3 lines per field of view in all cases [p  < 0.001]). Conclusions The majority of the elderly subjects did not have A‐lines, and B‐lines were observed in a high percentage. The reduction of impedance between lung parenchyma and soft tissues of the chest wall and the increased thickness of interlobular septa might explain these results.