Background: It is not known whether the vasodilatation seen in newborn piglets after porcine surfactant instillation is caused specifically by the surfactant itself or could be induced by the instillation of a similar volume of liquid. Further, effects on pulmonary hemodynamics in this model is not known

Subjects: Sixteen 3-5 days old piglets.

Interventions: Saline lung lavage. Bolus instillation of porcine surfactant 200 mg/kg or saline 0.9% (2.5 ml/kg). Mean arterial (ABP) and pulmonary (PAP) blood pressure were recorded continuously. Flowprobe around the common pulmonary artery measured cardiac output (CO).Systemic vascular resistance (SVR) and pulmonary vascular resistance (PVR) were calculated.

Results: ABP and SVR decreased significantly in the surfactant group only from 67 (±13) to 52 (±18) mmHg (p<0.05) for ABP, and 0.42 (±0.18) to 0.34 (±0.18) mmHg/ml/min/kg (p<0.01) for SVR. CO did not change in any group. PAP and PVR increased in the surfactant group 180 seconds after instillation and then returned to pre-instillation level without further decrease.

Conclusion: Porcine surfactant instillation results in a systemic vasodilatation within the first 5 minutes after instillation not seen after instillation of a similar volume of saline. No decrease in PAP or PVR were detected after surfactant instillation.