The appearance of "early" chest radiographs and the response to surfactant replacement therapy.

Abstract

We have assessed whether the appearance of the chest radiograph performed within the first 2 h of birth was predictive of the response to exogenous surfactant replacement therapy (SRT), as indicated by changes in sensitive indices of disease severity, that is lung volume (functional residual capacity (FRC)) and oxygenation (a/A ratio). 18 premature infants who received two doses of a synthetic surfactant (Exosurf) were studied. The appearances of chest radiographs taken prior to the first and immediately after the second dose of SRT were scored for lung volume, degree of inflation, presence of opacification, interstitial shadows and air bronchograms. At similar times, FRC was measured and the a/A ratio calculated. Although following SRT, the chest radiograph score decreased (p < 0.01) and the FRC (p < 0.01) and a/A ratio (ns) improved, there was no significant relationship between the change in chest radiograph score and either the change in FRC or a/A ratio. In addition, only the post-SRT chest radiograph appearance correlated significantly with the respective FRC, a/A ratio and outcome (death or oxygen dependency beyond 28 days). Although the appearance of an early chest radiograph is frequently used as an indicator of the need for SRT, these results demonstrate that, unlike the post-SRT radiograph, it is a poor predictor of the response to SRT and outcome.