Multiple breath washout is not useful in infants with bronchopulmonary dysplasia

Introduction: Children with bronchopulmonary dysplasia (BPD) have an increased risk for persistent structural and functional lung abnormalities. The multiple breath washout (MBW) test assesses efficiency of ventilation distribution and the lung clearance index (LCI) is considered a sensitive marker of ventilation inhomogeneity. Aim: To determine LCI and functional residual capacity (FRC) in infants with BPD and assess the correlations of LCI and FRC with lung structure and clinical parameters. We hypothesized that LCI would be elevated in infants with BPD and would correlate with structural changes. Methods: Preterm infants born ≤32 weeks gestational age (GA) with BPD were included. Demographics and clinical parameters were obtained from medical records. LCI and FRC were measured by MBW. Lung structure was assessed on chest CT with the PRAGMA-BPD scoring system. Volumes and percentages of regions with normal appearance, low attenuation, high attenuation and bronchial thickening were determined. Results: 15 infants with a median corrected age [IQR] of 7.0 [2.5] months were included. Median GA was 26.9 [1.3] weeks and birth weight was 907.8 [240] g. 14 infants had severe and one had mild BPD. Mean LCI was 7.2±0.7 and FRC was 162±52 ml. Only in 3 patients MBW was abnormal. Architectural distortion was present in all CTs. Median total lung volume was 238,7 [92.9] ml and healthy lung volume was 226,7 [108] ml. LCI and FRC did not correlate with lung volumes on CT and architectural distortion. FRC % predicted strongly correlated with GA (r=0.726, p Conclusion: LCI and FRC are not useful in the follow-up of patients with BPD.