INDEPENDENT LUNG VENTILATION WITH A SINGLE VENTILATOR USING A VARIABLE RESISTANCE VALVE

Independent lung ventilation using two ventilators has been attempted in the treatment of acute respiratory failure due to unilateral lung d isease. However, this method has been found to be cumbersome and diffi cult to use. We reasoned that a bifurcated endotracheal tube with a va riable resistance valve may enable us to change the inspiratory airway pressures and, hence, the inspired tidal volume to one lung using a s ingle ventilator. We tested this hypothesis in eight anesthetized shee p and created a bronchopleural fistula in one lung as a model of unila teral lung disease. A bifurcated endotracheal tube was placed to separ ate the ventilation to each lung and, through a ''Y'' connector, both right and left lungs were ventilated simultaneously with a single vent ilator. A variable resistance valve was placed between the ''Y'' conne ctor and the tube ventilating the experimental lung with bronchopleura l fistula. With a ventilator-generated peak inspiratory pressure of 31 +/-2 cm H2O, the airway pressure distal to the valve was randomly chan ged from 31 cm H2O to 23+/-2, 15+/-1, 8+/-1, and 0 cm H2O. This result ed in progressive diversion of tidal volume from the experimental lung to the control lung and an increase in exhaled tidal volume due to a decrease in air leak from the bronchopleural fistula. These data sugge st that a variable resistance valve may be used for independent lung v entilation using a single ventilator.