Study objective: We hypothesized that the continuous gas flow administration delivered through an insufflation catheter positioned above the carina during airway pressure release ventilation (APRV) would facilitate carbon dioxide (CO2) elimination, resulting in normocarbia with a substantially reduced peak airway pressure (Paw). To test this hypothesis, we compared intermittent positive pressure ventilation (IPPV), tracheal gas insufflation (TGI), APRV, and combined TGI and APRV (TGI+APRV).
Design: Animal study with random application of four ventilatory modes in a canine restrictive-thorax model with and without pulmonary edema.
Setting: Research laboratory at Kumamoto (Japan) University School of Medicine.
Subjects: Six mongrel dogs.
Interventions: Application of four ventilatory modes (IPPV, TGI, APRV, and TGI+APRV).
Measurements and results: TGI+APRV facilitated CO2 elimination. The peak Paw was significantly lower during TGI+APRV than during IPPV (nonpulmonary edema model: 15±4 vs 28±9 cm H2O; p<0.05; pulmonary edema model: 20±4 vs 34±10 cm H2O; p<0.05). Normocarbia was observed in both models. Neither TGI nor APRV alone maintained normocarbia.
Conclusion: The combined use of TGI and APRV is a more effective method of maintaining normocarbia with reduced peak Paw than either IPPV or APRV alone.