Tracheal gas insufflation associated with mechanical ventilation for CO2 removal.

Objective: Tracheal gas insufflation (TGI) either continuously, or at inspi ration, or at expiration, is a technique associated with mechanical ventila tion aimed to enhance CO2 elimination in favouring washout of anatomical de ad space. This article analyses the mechanism of action, the techniques and the effects of TGI in presence of hypercapnia, especially in the frame of ARDS in adults. Data sources: In addition to some historical or major references, the artic les on TGI published over the past five years have been searched in the Med line(R) data base. Study selection: Articles with data on TGI associated with mechanical venti lation were selected. Data extraction: Data on mechanisms of action, technical and practical aspe cts of TGI were extracted. Data synthesis: CO2 elimination is increased when the TGI catheter tip is c lose to the carina, when the gas jet is directed towards the latter, by a c ontinuous gas jet, by a high washing gas volume. The effect on oxygenation is minor. The work of breathing is decreased. An increased intracranial pre ssure is decreased. Circulatory effects are minor. The major risk is dynami c pulmonary over distension. Local complications include dessiccation and l esion of bronchial mucosa by the gas jet. Conclusion: In mechanically ventilated patients, additional TGI is a valuab le technique for decreasing anatomical dead space. TGI decreases hypercapni a during mechanical ventilation with limited tidal volumes in permissive hy percapnia. Further clinical studies with large series of patients are requi red to assess the benefits and the effect of TGI on outcome. (C) 2000 Editi ons scientifiques et medicales Elsevier SAS.