INTRATRACHEAL PERFLUOROCARBON ADMINISTRATION AS AN AID IN THE VENTILATORY MANAGEMENT OF RESPIRATORY-DISTRESS SYNDROME

Background. Respiratory distress syndrome carries a high morbidity and mortality when treated with mechanical ventilation with positive end- expiratory pressure. Perfluorocarbon liquids are employed in liquid ve ntilation due to low surface tension and high gas solubility. To asses s whether intratracheal administration of the perfluorocarbon, perflub ron, in combination with conventional mechanical ventilation could be of therapeutic benefit in respiratory distress syndrome, the authors t ested the effects of different doses of intratracheal perflubron admin istration on gas exchange and lung mechanics in adult animals with res piratory failure during a 6-h observation period. Methods: Respiratory failure was induced in 30 rabbits by saline lung lavage (arterial oxy gen tension < 100 mmHg at 100% oxygen with the following ventilator se ttings: tidal volume, 12 ml . kg-1; respiratory frequency, 30 per min; inspiratory/expiratory ratio, 1:2; and positive end-expiratory pressu re of 6 cm H2O). Twenty-four rabbits were treated with different perfl uorocarbon doses (3, 6, 9, and 12 ml . kg-1), and the remaining six se rved as controls while mechanical ventilation was continued with the a forementioned settings. Additionally, in ten healthy rabbits who were used as healthy controls, the lungs were mechanically ventilated eithe r alone or in combination with intratracheal perfluorocarbon administr ation (3 ml . kg-1) for 6 h. Results: In all treatment groups, arteria l oxygen pressure increased significantly (P < 0.0001) in a dose-relat ed fashion (193 +/- 40, 320 +/- 70, 353 +/- 125, and 410 +/- 45 mmHg a t 15 min), and peak airway pressures decreased significantly (range, 1 8-23%; P < 0.0001) from pretreatment values. These findings were in co ntrast to those for the control group. The improvements were time-depe ndent in all four tested perfluorocarbon doses. However, the improveme nts in pulmonary parameters could be extended to 6 h only in groups tr eated with 9 ml . kg-1 and 12 ml . kg-1 perflubron. At the end of the 6-h period, the data for these two groups showed significantly higher arterial oxygen pressure (230 +/- 84 and 197 +/- 130 mmHg, respectivel y; P < 0.05) and lower inflation pressures than the pretreatment data for these groups and the data for the control group al 6 h. There were no clinically significant changes in pulmonary parameters in healthy animals due either to mechanical ventilation alone or mechanical venti lation in combination with intratracheal perfluorocarbon administratio n for 6 h. Conclusions: The results of this study imply that there is no association between the lung mechanics and gas exchange parameters for mechanical ventilation in combination with intratracheal perfluoro carbon administration. The data suggest that this type of perfluorocar bon administration with conventional mechanical ventilation offers a s imple, alternative treatment of respiratory distress syndrome. With th is technique, adequate pulmonary gas exchange can be maintained at rel atively low airway pressures with high perfluorocarbon doses for sever al hours.