Surfactant decreases pulmonary vascular resistance and increases pulmonary blood flow in the fetal lamb model of congenital diaphragmatic hernia

Introduction: Experiments using animal models of neonatal respiratory distress syndrome have shown a decrease in pulmonary vascular resistance (PVR) with surfactant replacement, whereas studies with the lamb model of congenital diaphragmatic hernia (CDH) have demonstrated improvement in oxygenation...

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Published in:	Journal of pediatric surgery Vol. 31; no. 4; pp. 507 - 511
Main Authors:	O'Toole, Stuart J., Karamanoukian, Hratch L., Morin, Frederick C., Holm, Bruce A., Egan, Edmond A., Azizkhan, Richard G., Glick, Philip L.
Format:	Journal Article Conference Proceeding
Language:	English
Published:	Philadelphia, PA Elsevier Inc 01-04-1996 Elsevier
Subjects:	Animals Animals, Newborn Biological and medical sciences Female Hernia, Diaphragmatic - pathology Hernia, Diaphragmatic - physiopathology Hernias, Diaphragmatic, Congenital Hypertension, Pulmonary - pathology Hypertension, Pulmonary - physiopathology Lung - blood supply Lung - pathology Medical sciences Organ Size - drug effects Pneumology Pregnancy Pulmonary Gas Exchange - drug effects Pulmonary Gas Exchange - physiology Pulmonary Surfactants - pharmacology Regional Blood Flow - drug effects Regional Blood Flow - physiology Respiratory system : syndromes and miscellaneous diseases Sheep Vascular Resistance - drug effects Vascular Resistance - physiology Congenital diaphragmatic hernia pulmonary hypertension surfactant
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Summary:	Introduction: Experiments using animal models of neonatal respiratory distress syndrome have shown a decrease in pulmonary vascular resistance (PVR) with surfactant replacement, whereas studies with the lamb model of congenital diaphragmatic hernia (CDH) have demonstrated improvement in oxygenation and lung mechanics with this therapy. The aim of the present study was to measure the effects of surfactant replacement therapy on the pulmonary hemodynamics of the lamb model of CDH. Methods: Ten lambs with surgically created CDH and five control lambs were instrumented at term, with the placental circulation intact. Ultrasonic flow probes were positioned around the main pulmonary artery and the common origin of the left and right pulmonary arteries to record total lung and main pulmonary artery blood flow. Catheters were inserted to record systemic, pulmonary, and left atrial pressure. Five CDH animals received 50 mg/kg of surfactant by tracheal instillation just before delivery. All 15 animals were then ventilated for 4 hours. Results: Correcting the surfactant deficiency in the CDH lamb resulted in a significant increase in pulmonary blood flow, a decrease in PVR, and a reduction in right-to-left shunting. These improvements in hemodynamics were associated with a significant improvement in gas exchange over 4 hours. Conclusion: The fetal lamb model of CDH has elevated PVR in comparison to controls. Prophylactic surfactant therapy reduces this resistance and dramatically increases pulmonary blood flow while reducing extrapulmonary shunt. A surfactant deficiency may be partially responsible for the persistent pulmonary hypertension in neonates with CDH.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0022-3468 1531-5037
DOI:	10.1016/S0022-3468(96)90484-4