ULTRASONIC NEBULIZATION FOR EFFICIENT DELIVERY OF SURFACTANT IN A MODEL OF ACUTE LUNG INJURY - IMPACT ON GAS-EXCHANGE

We investigated the effect of ultrasonic nebulization versus instillat ion of exogenous surfactant on gas exchange abnormalities provoked by detergent inhalation in perfused rabbit lungs. Ventilation-perfusion ( (V)over dot A/(Q) over dot) distribution was assessed by the multiple inert gas elimination technique. For nebulization of natural bovine su rfactant (Alveofact(R)), an ultrasonic device was placed in line with the inspiratory gas flow tubing, manufacturing particles with a mass m edian aerodynamic diameter of similar to 4.5 mu M and high aerosol con centration. In vitro studies demonstrated biochemical and biophysical integrity of postnebulization surfactant. Lung aerosol deposition was monitored by a laserphotometric technique. In lungs with sham inhalati on of saline, tracheal instillation of surfactant (similar to 11 mg/kg body weight, infused over 50 min) provoked substantial (V) over dot A /(Q) over dot mismatch and limited shunt flow, whereas lung surfactant deposition by ultrasonic nebulization (similar to 7 to 9 mg/kg body w eight; nebulization time, 50 min) did not interfere with physiologic g as exchange. Tween 20 inhalation provoked severe (V) over dot/(Q) over dot mismatch with predominant shunt-flow (similar to 21%). This was n ot reversed by ''rescue'' application of instilled surfactant, but lar gely reversed by nebulized surfactant (shunt reduced to 5.5%; p < 0.01 ). Analysis of postaerosol lavage fluid demonstrated partial reconstit ution of surface activity by nebulized surfactant. We conclude that ul trasonic nebulization may be employed for efficient delivery of functi onally intact natural surfactant to the distal bronchoalveolar space. This approach effects rapid improvement of gas exchange in a model of acute homogeneous lung injury.