A stable model of respiratory distress by small injections of oleic acid in pigs

Objective. Development of a stable model of respiratory distress in pigs with oleic acid, fulfilling clinical criteria of the adult respiratory distress syndrome (ARDS). Design. Eight pigs (9.1 +/- 0.7 kg) were anesthetized with pentobarbital, paralyzed with tubocurarine and mechanically ventilated with an F-IO2 Of 0.6, an I:E ratio of 2.3 and a PEEP of 0.2 kPa. Oleic acid (dissolved 1.1 in 96% alcohol) was administered in a series of multiple injections of 0.1 mi until P-aO2 was lower than 8 kPa. Measurements and results: Careful titration of the oleic acid injections on guidance of the P-aO2 established a reproducible respiratory distress (P-aO2 = 7.3 +/- 0.8 kPa), in which gas exchange and hemodynamic variables were stable for at least 4 h. The number of oleic acid injections (22 +/- 11, mean and SD) varied between the animals. Conclusions: With the use of multiple injections of oleic acid, a stable model of early respiratory distress in pigs can be achieved, in spite of individual differences in sensitivity. Such a stable model allows for a diversity of studies on early respiratory distress.