Abstract: Objective: To evaluate effect of tracheal gas insufflation(TGI) on the elimination of CO₂ in COPD patients with respiratory failure. Methods: 8 COPD patients with rrespiratory failure were applied to TGI treament Using self-designed device, PaCO₂ and end expiratory carbondioxide pressure (P_etCO₂) as well as P_peak,P_pause,-P_aw were observed at the point while the patients received conventional mechanical ventilation(CMV),permisive hypercapnia(PHC) and PHC with different TGI flows (2 L/min,4 L/min,6 L/min). Results: TGI can significantly decrease the PaCO₂ and P_etCO₂ levels,the reduction effects of CO₂ are flow dependent.The mean reduction rate of PaCO₂ at the different TGI flows(2,4,6 L/min)under PHC condition by decreasing tidal volume are 27%,48% and 52% respectively.Levels of Ppeak,Ppause and-Pawin PHC condition are significantly lower than those of CMV,but all these three pressures are increased significantly after TGI intrducing and in a flow dependent mandent manner.There are no difference of the above pressures between the CMVand PHC condition.A certain level of intrinsic PEEP can be produced by TGI. Conclusion: Our results reveal that TGI can promote the CO₂ elimination profoundly and remain PaCO₂ in the relatively normal range under PHC condition without elevating airway pressure highly in COPD patients with respiratory failure.