Pulmonary administration of prostacyclin (PGI(2)) during partial liquid ventilation in an oleic acid-induced lung injury: inhalation of aerosol or intratracheal instillation?

Objective: The purpose of this study was to investigate the effects of aerosolized prostacyclin (A-PGI(2)) and intratracheally instilled prostacyclin (I-PGI(2)) during partial liquid ventilation (PLV) on gas exchange and pulmonary circulation in rabbits with acute respiratory distress. Design: Prospective control study. Setting: A research laboratory at a university medical centre. Subjects: Sixty-nine Japanese white rabbits. Intervention: Lung injury was induced by oleic acid and the animals were divided into five groups of ten each: a mechanical gas ventilation (GV) group, an A-PGI(2) group, a PLV group, an A-PGI(2)+PLV group and an I-PGI(2)+PLV group. PLV, A-PGI(2)+PLV and IPGI(2)+PLV groups received 15 ml/ kg perflubron intratracheally while receiving mechanical GV. A-PGI(2) and A-PGI(2)+PLV groups received aerosolized PGI(2) (50 ng/kg/min) in combination with GV or PLV, respectively. The I-PGI(2)+PLV group was instilled 50 ng/kg/min PGI(2) in tratracheally in combination with PLV. Result: After lung injury, all animals developed hypoxia, hypercarbia and pulmonary hypertension. The improvement of partial pressure of arterial oxygen (PaO2) in the A-PGI(2) and PLV groups was transient, whereas the A-PGI2+PLV and IPGI2+PLV groups showed consistent improvement throughout the experiment. The PaO2 values of the I-PGI(2)+PLV group were significantly higher than those of the other groups 120 min after treatment. The mean pulmonary artery pressure (PAP) significantly decreased after treatment in the A-PGI(2), A-PGI(2)+PLV and I-PGI(2)+PLV groups. Conclusions: The results suggest that both aerosolized and intratracheally instilled PGI(2) improve oxygenation and reduce PAP during PLV in oleic acid lung injury.