thromboxane-b2 and Hernias--Diaphragmatic--Congenital

Pulmonary hypertension is a major source of morbidity and mortality in infants born with congenital diaphragmatic hernia (CDH). Increased pulmonary vascular resistance leads to right-to-left shunting, which is evident as decreases in the PaO2 measured in postductal arterial blood. Thromboxane A2 (TXA2), a vasoconstrictor, and prostacyclin (prostaglandin I2, PGI2), a vasodilator, have been studied as possible mediators of pulmonary hypertension in certain conditions of the newborn, including congenital diaphragmatic hernia (CDH). The goal of our study was to determine the association of TXA2 and PGI2 levels with hypoxemia in infants born with CDH. Eleven newborn infants with severe respiratory insufficiency (birth weight 2.0-4.1 kg; gestational age 32-42 weeks) were studied 0-5 days after surgical repair of CDH. Umbilical artery samples were collected for arterial blood gas determinations and radioimmunoassay of thromboxane B2 (TXB2) and 6-keto prostaglandin F1 alpha (6-keto-PGF1 alpha), stable metabolites of TXA2 and PGI2, respectively. Postductal arterial hypoxemia (reflected by a low a-A ratio, the ratio of oxygen tension in arterial blood to that in the alveolus) was associated with increases in TXB2 (r = -0.71, P = 0.004) and 6-keto-PGF1 (r = -0.65, P = 0.017). The a-A ratio also correlated inversely with TXB2/6-keto-PGF1 alpha (r = -0.50, P = 0.01), suggesting an increased influence of the vasoconstrictor TXA2.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: 6-Ketoprostaglandin F1 alpha; Arteries; Carbon Dioxide; Hernia, Diaphragmatic; Hernias, Diaphragmatic, Congenital; Humans; Hydrogen-Ion Concentration; Hypoxia; Infant, Newborn; Oxygen; Partial Pressure; Respiration; Thromboxane B2

A prospective study of 10 neonates with congenital diaphragmatic hernia and five controls to determine the importance of prostanoid concentrations perioperatively and the relation with persistent pulmonary hypertension (PPH) is reported. In neonates with congenital diaphragmatic hernia postoperative concentrations of the vasoconstrictor thromboxane B2 rose significantly and were higher during episodes of PPH; this rise may provoke PPH and subsequent right to left shunting.

Topics: 6-Ketoprostaglandin F1 alpha; Airway Resistance; Hernia, Diaphragmatic; Hernias, Diaphragmatic, Congenital; Humans; Infant, Newborn; Oxygen; Persistent Fetal Circulation Syndrome; Postoperative Period; Prospective Studies; Respiratory Function Tests; Thromboxane B2

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.

Topics: 6-Ketoprostaglandin F1 alpha; Hernia, Diaphragmatic; Hernias, Diaphragmatic, Congenital; Humans; Infant, Newborn; Lung; Thromboxane B2; Thromboxanes; Tolazoline; Vascular Resistance