Extremely low flow tracheal gas insufflation of helium-oxygen mixture improves gas exchange in a rabbit model of piston-type high-frequency oscillatory ventilation

OBJECTIVE The purpose of this study was to show the effects of the tracheal gas insufflation (TGI) technique on gas exchange using helium-oxygen mixtures during high-frequency oscillatory ventilation (HFOV). We hypothesized that a helium-oxygen mixture delivered into the trachea using the TGI technique (0.3 L/min) would enhance gas exchange during HFOV. METHODS Three rabbits were prepared and ventilated by HFOV with carrier 70% helium/oxygen or 70% nitrogen/oxygen gas mixture with TGI in a crossover study. Changing the gas mixture from nitrogen70% to helium70% and back was performed three times per animal with constant ventilation parameters. RESULTS Compared with the nitrogen-oxygen mixture, the helium-oxygen mixture of TGI reduced PaCO2 by 7.6 mmHg (p < 0.01) and improved PaO2 by 14 mmHg (p < 0.01). Amplitude during TGI was significantly lower with the helium-oxygen mixture than with the nitrogen-oxygen mixture (p < 0.01) and did not significantly affect mean airway pressure. CONCLUSIONS This study demonstrated that a helium-oxygen mixture delivered into the trachea using the TGI technique would enhance CO2 elimination and improve oxygenation during HFOV.