Respiratory alkalosis attenuates thromboxane-induced pulmonary hypertension

Mechanically induced respiratory alkalosis decreases pulmonary arterial pressure in infants with persistent pulmonary hypertension of the newborn and in newborn lambs with hypoxia-induced pulmonary hypertension. Since thromboxane A2 may mediate the pulmonary hypertension in infants with Group B beta-hemolytic streptococci and Escherichia coli pneumonia, we studied the effect of respiratory alkalosis on thromboxane-induced pulmonary hypertension. A specific thromboxane A2-mimetic, U46619, was infused into six normoxic, sedated, mechanically ventilated lambs. U46619 produced pulmonary hypertension which was significantly attenuated during respiratory alkalosis. These results support the use of respiratory alkalosis to treat infants and children with pulmonary hypertension regardless of the presumed etiology.