INTRATRACHEAL PULMONARY VENTILATION (ITPV) - CONTROL OF POSITIVE END-EXPIRATORY PRESSURE AT THE LEVEL OF THE CARINA THROUGH THE USE OF A NOVEL ITPV CATHETER DESIGN

A new mode of pulmonary ventilation called intratracheal pulmonary ven tilation (ITPV) was studied. Briefly, a continuous flow of air/oxygen is introduced through a small catheter, the tip of which is positioned at the carina, with a diffuser mounted at its distal end. A timed exp iration valve, when closed, provides for inspiration; when open, it pr ovides for expiration. The system as first described had a potential f or significant back pressure at the level of the carina, which was mor e at rapid gas flows and with smaller endotracheal tubes. We have now mounted a venturi on the tip of the catheter (reverse thrust catheter [RTC]) that avoids back pressure, and which facilitates expiration. At respiratory rates from 10 to 120/min, the ITPV system with the RTC ma intained end-expiratory pressure at the level of the carina at, or nea r 0 cm H2O. Compared to conventional mechanical ventilation, at identi cal respiratory rates, this system reduced tidal volume by one half at the lowest respiratory rates, and by as much as two thirds at the hig hest respiratory rates, with a proportional decrease in peak inspirato ry pressure. ITPV has the smallest minute volume ventilation of any co nventional or nonconventional mode of pulmonary ventilation.