Tracheal gas insufflation (TGI) as an adjunct to mechanical ventilation delivers fresh gas into the central airways continuously or in a phasic fashion to improve the efficiency of alveolar ventilation or to minimize the ventilatory pressure requirements. Recently, TGI has received increasing attention as an adjunctive tool for lung-protective mechanical-ventilation strategies. Experimental studies in animal and mechanical-lung models have been essential in the quest to understand TGI's mechanisms of action and operational characteristics. Experimental studies in animal models of lung injury have substantiated the potential role of TGI in clinical practice. Currently, the evolution of TGI is entering a phase in which overcoming obstacles to clinical implementation may lead to the development of commercial systems with more widespread TGI application.