AIRWAY MUSCLE IN INFANTS WITH CONGENITAL DIAPHRAGMATIC-HERNIA - RESPONSE TO TREATMENT

Background/Purpose: Airway muscle hyperactivity and chronic lung disea se frequently follow congenital diaphragmatic hernia (CDH) treatment. The aim of this study was to compare the quantity of airway muscle and alveolar ductal artery muscle in CDH infants after Various treatments . Methods: Five groups were studied postmortem: CDH, died within 24 ho urs, without high ventilatory assistance (n = 3); CDH, various extraco rporeal membrane oxgenation (ECMO) durations, without high ventilatory assistance (n = 4); CDH, various ECMO durations, with high ventilator y assistance (n = 7); no CDH, without high ventilatory assistance (n = 12); and no CDH, with high ventilatory assistance and bronchopulmonar y dysplasia (BPD) (n = 5). Sections from standardized fixed lu ngs wer e immunohistochemically stained for alpha-smooth muscle actin. Muscle surrounding conducting airways from small preterminal bronchioles to b ronchi was quantitated in both the ipsilateral and contralateral lungs with computerized image analysis. Similarly, muscle mass was quantita ted in alveolar ductal arteries. Results: CDH infants with low ventila tory assistance, regardless of postnatal age, had the same quantity of airway muscle as low ventilatory assistance controls. Infants with CD H and prolonged high ventilatory assistance had significantly more mus cle throughout the conducting airways, similar to BPD infants without CDH, even though the CDH infants had significantly less exposure to hi gh ventilatory assistance. With both low and high ventilatory assistan ce, the quantity of muscle in both the ipsilateral and contralateral l ungs was similar. In contrast, small acinar arteries in CDH infants ha ve increased muscle mass at birth. This muscle is decreased by ECMO bu t persists in CDH infants with high ventilatory assistance. Conclusion s: The authors show that postnatally, CDH infants acquire increased mu scle quantity throughout the conducting airways, in both the ipsilater al and contralateral lungs, with relatively short exposure to high ven tilatory assistance. The normal decrease in acinar arterial mass that occurs postnatally is delayed in CDH infants with high Ventilatory ass istance. Copyright (C) 1998 by W.B. Saunders Company.