| Abstract | BACKGROUND/PURPOSE: Pulmonary hypoplasia is a major cause of mortality and
morbidity in infants with congenital diaphragmatic hernia (CDH). Pulmonary hypoplasia is
characterized by low volume lungs, and affected infants are likely to have a low lung area
on their chest radiograph. The authors assessed whether, in CDH infants, computer-assisted
analysis of the chest radiograph lung area gave an accurate indication of lung volume, and if
a low lung area was a better predictor of poor outcome (death or oxygen dependency at 28
days) than other test results. METHODS: Comparisons were made of the radiographic lung
area derived by computer-assisted analysis and lung volume, assessed by measurement of
functional residual capacity (FRC) on day 1 before surgical intervention and on the first
postoperative day. Compliance was measured, and the maximum and modified ventilation
indices and maximum Paco2 also was noted. Twenty-five CDH infants with a median
gestational age of 38 weeks were studied; 18 had FRC measurements preoperatively.
RESULTS: Both preoperatively and postoperatively, the lung areas and FRCs correlated
significantly (r = 0.51, P<.05; r = 0.76, P<.02, respectively). Eleven infants had a poor
outcome (5 infants died without an operation); that group preoperatively differed
significantly from those with a good outcome with respect to having a lower compliance
(P<.02) and higher maximum ventilation index (P<.01) and maximum modified ventilation
index (P<.05). Only postoperatively did infants with a poor outcome versus good outcome
have a significantly lower lung area (P<.05); they also had a lower increase in lung area
preoperatively to postoperatively (P<.01). Receiver operator characteristic curves were
constructed; comparison of the areas under the curves showed that preoperatively, a low
compliance and high ventilation index were the best predictors of poor outcome.
Postoperatively, a low lung area performed as well as the ventilation indices.
CONCLUSION: Computer-assisted analysis of the lung area on the chest radiograph is
useful in predicting outcome in CDH infants postoperatively but not preoperatively. |