Intratracheal gas insufflation (TGI)is considered an effective supplement of artificial pulmonary ventilation (UPV)reducing the PaCO2 level along with reduction of its pressure and volume effects by reducing the ventilation volume (VT).The principle of the effect of TGI is reduction of the ventilation dead space (VD)by rinsing it with fresh gas brought in to the level of the carina.Due to reduction of VD the ratio VT/VD changes and thus also the conditions for alveolar ventilation (VA)change.It is obvious that during non-conventional ventilation regimes such as in particular high frequency oscillation ventilation (HFOV)when VT is close to VD the change of their ratio will play an important role during the blood gas exchange.Authors ’investigation was made with the objective to compare the effect of a combination of TGI with conventional UPV (CV)and with HFOV on blood gas exchange, pressure and volume parameters of ventilation and to assess the optimal TGI flow (QTGI)to achieve an effect on PaCO2,PaO2 and VT ensuing from reduction of VD.For investigation of each method and their comparison two groups of nine healthy rabbits were used (weight 1.8 -3.2 kg),with air ventilation (FiO2 =0.21).For CV and HFOV volume controlled ventilation was selected. Measurements and main results:A statistically significant drop of PaCO2 (-3.9 ±0.9 Torr),increase of PaO2 (8.2 ±3.6 Torr)and decline of VTCELK (-12 ±3.1 %)during combination CV+TGI is apparent already during a flow of QTGI =0.5 l/min (for all variables p <0.001).During the subsequent increased flow QTGI the improvement of blood gas exchanges and their statistical significance as compared with the original state (QTGI =0 l/min)increase further with limitation of the effect in the region of QTGI =2 l/min. A statistically significant drop of PaCO2 (-3.0 ±1.7 Torr)and increase of PaO2 (6.4 ±2.2 Torr)and drop of VTCELK (-7.1 ± 1.7 %%)during combinations of HFOV +TGI occurs already during a flow of QTGI =0.5 l/min (for all variables p <0.005).During a further increase of the QTGI flow the improvement of blood gas exchange and their statistical significance as comparedwith the original state (QTGI =0 l/min)improves further without limitation in the accessible area of measurements. On comparison of CV+TGI and HFOV+TGI it is apparent that for improvement of the blood gas exchange the combination of HFOV and TGI is significantly better as compared with the combination CV+TGI already at QTGI =1 l/min (
=-4.9 ±0.8 Torr for CV as compared with -9 ±2.1 Torr for HFOV,p*<0.005 and
=12.3 ±4.5 Torr as compared with 22.9 ±3.7 Torr,p*<0.0005.At QTGI =2 l/min the difference is even more significant (
=-5.9 ±1.0 Torr as compared with -12.3 ±1.8 Torr,p*<0.00005 and
=13.8 ±4.1 Torr as compared with 32.4 ±3.7 Torr,p*<0.000005). When investigating the effectiveness of CV+TGI and HFOV+TGI fromthe aspect of reduction of volume effects on ventilation it is apparent that comparison of the percentage reduction of VTCELK between the two methods does not lead to significant differences between them (p >0.01).

        Key words: artificial pulmonary ventilation,tracheal gas insufflation,high frequency oscillatory ventilation