PULMONARY VASCULAR ABNORMALITIES IN CONGENITAL DIAPHRAGMATIC-HERNIA

Persistent pulmonary hypertension poses a significant problem to the s urgeon managing an infant with congenital diaphragmatic hernia. It is likely that a number of abnormalities contribute to this pathophysiolo gic entity. These include: (1) in the hypoplastic lung the overall cro ss-sectional area of the pulmonary vascular bed is reduced, (2) the mu scular arteries are hypertrophied and extend more peripherally than no rmal, (3) the pulmonary vessels are more labile than normal and are ov erly sensitive to the normal stimuli of vasoconstriction, and (4) the immature surfactant-deficient lung is predisposed to barotrauma and at electasis, resulting in alveolar hypoxemia which contributes to pulmon ary hypertension. All of these interfere with the ability of the lund to accept the increase in pulmonary blood flow required by the transit ional circulation. If this impairment reaches a level such that the lu ng cannot accept the right ventricular output then pulmonary hypertens ion will ensue and a poor outcome can be anticipated.