Lung ultrasound in the elderly population: investigating the limit between physiological and pathological patterns

Purpose: The senile lung undergoes paraphysiological changes which have been described in several radiological and CT studies, but never investigated through ultrasound. The aim of the present study was to evaluate a group of elderly-nonsmoker- healthy patients in comparison with young subjects, by using ultrasound examination. Methods and Materials: 100 elderly subjects (> 70years-mean age: 79.4±6.9) and 50 young subjects (< 55years-mean age: 32.5±12.1) were submitted to lung ultrasound examination. We analysed the anterior, lateral and posterior surface of each lung to evaluate the presence/absence of A-lines and B-lines. Fisher test was chosen to compare data obtained in the two groups. Results: Absence of A-lines was found in 94/100-94.0% of elderly versus 2/50-4.0% of young subjects (p < 0.0001). Presence of B-lines was detected in 37/100-37.0% of elderly, with a higher prevalence in posterior lung fields; the number of B-lines was²3 per field (pf) in 27/37-73.0%, > 3pf in 2/37-5.4%; both ²3 and > 3pf-depending on the evaluated field in 8/37-21.6%. By contrast, 5/50-10.0% young subjects showed B-lines (²3pf in all of cases)- p=0.0004. Conclusion: To avoid misdiagnosis, we should consider that physiological ultrasound lung findings could be different among old and young people. The majority of old individuals did not present A-lines; moreover in a high percentage, B-lines were observed (²3pf in most of them). These results could be explained by a reduction of impedance between lung parenchyma and soft tissue (absence of A-lines) and by an increased thickness of interlobular septa (presence of B-lines). Further studies should be proposed to define a cut-off between normal and pathological pattern.