Original Article
Lung function at term reflects severity of bronchopulmonary dysplasia

https://doi.org/10.1016/j.jpeds.2004.08.044Get rights and content

Objective

To test whether infants with bronchopulmonary dysplasia (BPD) express the same functional impairments at term as healthy, preterm infants, and whether clinical severity of BPD is qualitatively or quantitatively related.

Study design

Prospective measurements on a consecutive sample of 50 infants with BPD and 19 healthy preterm controls in a university hospital. BPD infants were classified as “severe,” “moderate,” or “mild,” according to their need for oxygen. A multiple-breath nitrogen wash-out method was used to assess functional residual capacity (FRC) and gas mixing efficiency. Mechanical variables were estimated by the occlusion test.

Results

Infants with severe BPD had lower FRC, less efficient gas mixing, and higher specific conductance than those with mild and moderate BPD, and the preterm controls. Mild and moderate BPD did not differ in any property from each other but differed from controls in the same variables. The elastic properties of the respiratory system appeared unaffected by BPD.

Conclusions

The ventilatory impairments in BPD were of the same nature as in healthy preterm infants when compared with term infants, but their magnitude was related to the clinical severity of the BPD. Gas mixing efficiency together with FRC appears to be useful to assess lung development in BPD.

Section snippets

Study design

This prospective study was designed to compare three groups of preterm infants with mild, moderate, and severe BPD, respectively, together with a sample of healthy controls, with respect to four different variables of lung development and function at a postmenstrual age (PMA) corresponding to term. FRC, compliance, resistance of the respiratory system, and gas mixing efficiency were assessed. The study was approved by the Board of Ethics of the Medical Faculty at Göteborg University. Informed

Results

Fifty infants with BPD were included in the study. (Table II) The BPD groups had similar gestational age at birth, birth weight, and PMA at time of study. The control group was more mature at birth, and they had about 1 week greater PMA and body weight at the time of study. There were more females in the mild BPD group and more males in the severe BPD group. However, neither gestational age nor gender contributed significantly to the variance of any of the lung function variables in multiple

Discussion

We measured different aspects of ventilatory function in infants with BPD, classified according to recently proposed criteria, in order to determine if the same variables are affected as are altered by uncomplicated preterm delivery. We also wanted to study whether clinical criteria, based on severity of disease, correlate with different types and degrees of lung involvement when examined close to term. Although the BPD groups had similar gestational ages at birth, the controls were more

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