Congenital diaphragmatic hernia: association between pulmonary vascular resistance and plasma thromboxane concentrations.

After repair of a Bochdalek diaphragmatic hernia, shunting of blood away from the lungs produced progressive hypoxaemia in a neonate. Changes in plasma concentrations of the vasoconstrictor prostanoid thromboxane were associated with changes in pulmonary vascular resistance in this infant. Plasma concentrations of the vasodilator prostanoid prostacyclin were also monitored during acute changes in pulmonary vascular resistance. Tolazoline administration was followed by reductions in pulmonary vascular resistance and in plasma thromboxane and prostacyclin values. Further studies indicated that tolazoline inhibits platelet thromboxane synthesis and vascular prostacyclin synthesis. These data suggest that thromboxane plays a part in the increased pulmonary vascular resistance that occurs after repair of congenital diaphragmatic hernia and that tolazoline may reverse pulmonary hypertension by a mechanism additional to its known action as an alpha adrenergic blocking agent and its effect on histamine release.