HEMODYNAMICS AND TISSUE BLOOD-FLOW AFTER PORCINE SURFACTANT REPLACEMENT IN SURFACTANT-DEPLETED NEWBORN PIGLETS

In 22 newborn piglets we studied the effect of hypovolemia or hypoxemi a on hemodynamics and regional blood flow after instillation of porcin e surfactant. Surfactant deficiency was obtained by repeated lung lava ge, and blood flow measurements were carried out using radioactive mic rospheres. Three groups of piglets were studied, controls (a = 8), hyp ovolemia (n = 7), and hypoxemia (n = 7). Three to five minutes after i nstillation of surfactant, mean arterial blood pressure decreased sign ificantly in all three groups with a mean decrease (+/-SD) of 31(+/-12 ), 33(+/-9), and 29(+/-9) mm Hg, respectively (p < 0.01 in all three g roups). Systemic vascular resistance decreased significantly in all th ree groups immediately after surfactant instillation (p < 0.01) and re turned to presurfactant level after 60 min. Blood how did not change a fter surfactant instillation in any of the three groups, in neither sk in, muscle, pancreas, brain, nor retina. In liver, kidney, intestine, and choroidea there was a decrease in blood how immediately after inst illation with return to presurfactant levels within 60 min. Hypoxemia or hypovolemia before surfactant instillation did not increase the hem odynamic instability. The decrease in mean arterial blood pressure was caused by a vasodilation and not by a reduced cardiac output.