Objectives: Lung ultrasound can reliably diagnose pulmonary atelectasis. The object of this study is to determine the most efficient region to assess changes in atelectasis in children with congenital heart disease under general anesthesia.
Design: Randomized controlled trial.
Setting: Operating room at university-affiliated children's hospital.
Patients: Children between 3 months and 3 years old, scheduled for elective congenital heart disease surgery under general anesthesia.
Interventions: Forty children with congenital heart disease were randomly allocated to either a 5 cm H2O positive end-expiratory pressure group or a standard therapy control group.
Measurements and main results: Preoperative lung ultrasound was performed twice in each patient-after 1 and 15 minutes of mechanical ventilation. Atelectatic areas and B-lines were compared between two examinations. Different ultrasound regions were evaluated using Bland-Altman plots. The occurrence rate of atelectasis was much higher in inferoposterior lung regions (Scans 4-6) than in anterior and lateral regions (Scans 1-3). The median (interquartile range) lung ultrasound scores were lower in the positive end-expiratory pressure group than in the control group after treatment: 8 (3.3-9.8) versus 13 (8.3-17.5; p < 0.001). The atelectatic area was significantly decreased after treatment in the positive end-expiratory pressure group: 128 mm (34.5.5-213.3 mm) versus 49.5 mm (5.3-75.5 mm; p < 0.001). Bland-Altman plots revealed concordance between measurements in Scans 1-6 and those in Scans 4-6. In the posterior axillary line regions, changes in atelectatic area were significantly larger in the positive end-expiratory pressure group than in the control group (p = 0.03, 0.007, and 0.018).
Conclusions: Lung ultrasound in inferoposterior lung regions may be more likely to reflect changes in atelectasis and save examination time; 5 cm H2O positive end-expiratory pressure may be useful in lung reaeration and can reduce, but not eliminate, atelectasis in children with congenital heart disease.