Evaluation of lung function after intratracheal perfluorocarbon administration in healthy animals

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Abstract
To investigate the effects of partial liquid ventilation (i.e., mechanical ventilation in combination with intratracheal administration of perfluorocarbon) on lung function, with particular attention to the integrity of the alveolocapillary membrane in healthy adult animals. Prospective, randomized, controlled study. Laboratory at the Department of Experimental Anesthesiology, Erasmus University Rotterdam. Ten adult male New Zealand rabbits. Five rabbits were intratracheally treated with 12 mL/kg of perfluorocarbon while conventional mechanical ventilation (volume-controlled, tidal volume of 12 mL/kg, respiratory rate of 30 breaths/min, inspiration/expiration ratio of 1:2, positive endexpiratory pressure of 2 cm H2 O, and an FIO2 of 1.0) was applied for 3 hrs. To assess the permeability of the alveolocapillary membrane, pulmonary clearance of inhaled technetium-99m-labeled diethylenetriamine pentaacetic acid (sup 99m Tc-DTPA) measurements were performed at 3 hrs and compared with data from the control group (n equals 5) treated with mechanical ventilation only, using the same ventilatory parameters. Pulmonary gas exchange and lung mechanical parameters were measured in both groups at 30-min intervals. Mean values for PaO2 in the perfluorocarbon group, although at adequate levels, were less than those values of the control group during the 3-hr study period (370 plus minus 44 vs. 503 plus minus 44 torr at 3 hrs [49.3 plus minus 5.9 vs. 67.1 plus minus 5.9 kPa]). Peak and mean airway pressures were higher in the perfluorocarbon group (ranging from 1.9 to 3.4 cm H2 O and 0.7 to 1.3 cm H2 O, respectively) compared with the control group, while end-inspiratory airway pressure was similar in both groups. The half-life of99m Tc-DTPA was 83.7 plus minus 24.5 mins in the control group, which was significantly longer (p less than .01) than in the perfluorocarbon group (49.8 plus minus 6.1 mins). These findings suggest that partial liquid ventilation with perfluorocarbons lowers pulmonary gas exchange in healthy animals, and the increased pulmonary clearance of99m Tc-DTPA after 3 hrs of this type of ventilatory support may reflect minimal reversible changes in the lung surfactant system.