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 Pa-O2/Fi(O2) 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 (VT); 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 Pa-O2/Fi(O2) from 189 +/- 13 torr (25.2 +/- 1.7 kPa) to 383 +/- 44 torr (51.1 +/- 5.9 kPa) (p < .01) and decreased Pa-CO2 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 VT from 15 mL/kg to 3.5 mL/kg while keeping EELV constant decreased Pa-O2/Fi(O2) to 288 +/- 49 torr (38.4 +/- 6.5 kPa) (not significant) and normalized Pa-CO2. 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 VT without any adverse effect on Pa-CO2.