Abstract 1908: Airway Pressure Release Ventilation Improves Pulmonary Blood Flow and Cardiac Output Following Cardiac Surgery for Congenital Heart Disease
Introduction: Airway Pressure Release Ventilation (APRV) maintains a constant airway pressure (Paw) with brief intermittent pressure reductions and permits spontaneous respiration without triggering the ventilator. Elevated Paw can critically reduce pulmonary blood flow (QP). We hypothesized that spontaneous ventilatory effort transmitted to the pleural space during APRV would result in a transient decrease in intrapleural pressure and increase QP follow surgery for Tetralogy of Fallot or cavopulmonary connection (Glenn, Fontan).
Methods: After obtaining IRB approval and patient consent, we studied children immediately following surgery. QP and cardiac output (CO) were compared with APRV and positive pressure ventilation, with/without spontaneous ventilation. APRV was compared with positive pressure ventilation in the absence and presence of spontaneous respiratory effort in 4 × 30-minute phases. Oxygen consumption (VO2) was measured (mass spectrometer), and QP and CO calculated (Fick equation). Constant levels of PaCO2 and mean Paw were targeted in all study phases.
Results: Nineteen patients were enrolled in the study, 9 following repair of tetralogy of Fallot and 10 following a Glenn/Fontan operation. In the absence of spontaneous ventilation, there were no differences in QP or any of the measured gas exchange or hemodynamic parameters. In the presence of spontaneous ventilation, there were significant differences in the measured parameters (Table⇓).
Conclusion: Ventilation with APRV (at comparable mean Paw) improves QP, and other gas exchange/hemodynamic variables compared with positive pressure ventilation in children following cardiac surgery. Although this study focused on tetralogy of Fallot repair and Glenn/Fontan operations, the improved cardiopulmonary interactions may be beneficial in other situations where hemodynamics are adversely modified by positive pressure ventilation.