Selective tracheal gas insufflation during partial liquid ventilation improves lung function in an animal model of unilateral acute lung injury

OBJECTIVE During unilateral lung injury, we hypothesized that we can improve global lung function by applying selective tracheal gas insufflation (TGI) and partial liquid ventilation (PLV) to the injured lung. DESIGN Prospective, interventional animal study. SETTING Animal laboratory in a university hospital. SUBJECTS Adult mixed-breed dogs. INTERVENTIONS In six anesthetized dogs, left saline lung lavage was performed until Pao2/Fio2 fell below 100 torr (13.3 kPa). The dogs were then reintubated with a Univent single-lumen endotracheal tube, which incorporates an internal catheter to provide TGI. In a consecutive manner, we studied 1) the application of 10 cm H2O of positive end-expiratory pressure (PEEP); 2) instillation of 10 mL/kg of perflubron (Liquivent) to the left lung at a PEEP level of 10 cm H2O (PLV+PEEP 10 initial); 3) application of selective TGI (PLV+TGI) while maintaining end-expiratory lung volume (EELV) constant; 4) PLV+TGI at reduced tidal volume (< ˙;V>t); and 5) PLV+PEEP 10 final. MEASUREMENTS AND MAIN RESULTS Application of PLV+PEEP 10 initial did not change gas exchange, lung mechanics, or hemodynamics. PLV+TGI improved Pao2/Fio2 from 189 ± 13 torr (25.2 ± 1.7 kPa) to 383 ± 44 torr (51.1 ± 5.9 kPa) (p < .01) and decreased Paco2 from 55 ± 5 torr (7.3 ± 0.7 kPa) to 30 ± 2 torr (4.0 ± 0.3 kPa) (p < .01). During ventilation with PLV+TGI, reducing < ˙;V>t from 15 mL/kg to 3.5 mL/kg while keeping EELV constant decreased Pao2/Fio2 to 288 ± 49 torr (38.4 ± 6.5 kPa) (not significant) and normalized Paco2. At this stage, end-inspiratory plateau pressure decreased from 19.2 ± 0.7 cm H2O to 13.6 ± 0.7 cm H2O (p < .01). At PLV+PEEP 10 final, measurements returned to those observed at previous baseline stage (PLV+PEEP 10 initial). CONCLUSIONS During unilateral lung injury, PLV with a moderate PEEP did not improve oxygenation, TGI superimposed on PLV improved gas exchange, and combination of TGI and PLV allowed a 77% reduction in < ˙;V>t without any adverse effect on Paco2.