Daily changes of the area of density in the dependent lung region – evaluation using transesophageal echocardiography

Abstract.

Objective: To evaluate the daily changes of the area of density using transesophageal echocardiography (TEE) in acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) patients. Design: Retrospective observational study. Setting: General ICU in a university hospital. Patients: Fifteen patients with ARDS or ALI who underwent TEE examination for more than 5 days. Measurements: Densities in the lower left lung region were observed through the descending aorta by TEE. Daily changes of the area of density were evaluated. The areas of density estimated by TEE were compared with those obtained by computed tomography (CT). The relation between the area of density and PaO₂/FIO₂ was calculated. Results: The area of density in the dependent lung region measured by TEE was 11.1±5.7 cm² (mean ± SD) at the mid-esophageal position. The area of density in ARDS patients changed daily from 12.0±2.8 cm² to 8.5±6.7 cm².The areas of density evaluated using TEE in the left lung correlated significantly with those estimated using CT (r=0.72, p<0.01). In addition, we found a significant correlation between PaO₂/FIO₂ and the area of density estimated by TEE (r=–0.53, p<0.05). Conclusion: Using TEE, we could evaluate daily changes of the area of density in the dependent lung region in the intensive care situation. The areas of density in ARDS patients changed from day to day following the changes of oxygenation.