We have previously shown that surfactant instillation in lung lavaged newborn piglets induces a systemic vasodilation and a decrease in MABP. The purpose of this study was to investigate if pulmonary hemodynamics were influenced by surfactant instillation as well. Two groups of lung lavaged piglets (3-6 d) were studied. Group 1 (n=8) received porcine surfactant 200 mg/kg (2.5 ml/kg) as bolus instillation through the E.T. tube. Group 2 (n=8) had instillation of the same volume of saline 0.9%. Mean arterial (ABP), mean pulmonary (PAP) and central venous pressures (CVP) and pressure in the left atrium (LAP) were recorded continuously through indwelling catheters. A thoracotomy was performed and an ultrasonic transit time flowprobe was fitted around the common pulmonary artery to measure cardiac output. Systemic vascular resistance (SVR) and pulmonary vascular resistance (PVR) were calculated. Mean values (±SD). * = p < 0.05 ABP and SVR decreased significantly only in group 1 2.5 min after instillation. PAP and PVR increased significantly in group 1 during the first two minutes after instillation (p<0.05) probably reflecting a transient hypoxic vasoconstiction, but were not significantly increased at 2.5 minutes. No other significant changes in PAP or PVR occurred after instillation.Table

Table 1

Conclusion: Instillation of porcine surfactant causes a decrease in ABP and SVR that is not seen after instillation of a similar volume of saline. By contrast to the systemic circulation PAP and PVR do not decrease.