Active decompression during automated head-up cardiopulmonary resuscitation

Background: The combination of active compression-decompression cardiopulmonary resuscitation (ACD-CPR) with an impedance threshold device (ITD) and controlled head-up positioning (AHUP-CPR) is associated with improved outcomes compared with conventional CPR (C-CPR). This study focused on the role of active decompression (AD) during AHUP-CPR. Methods: Farm pigs (n = 10, 40 kg) were anesthetized, intubated and ventilated. Physiological parameters and right ventricular pressure-volume loops were recorded continuously. Ventricular fibrillation was induced and left untreated for 10 mins, followed by automated C-CPR (2 min), ACD + ITD CPR in the flat position (2 min), and then AHUP-CPR with 3 cm of lift above the neutral chest position. After 15 min of CPR, AD was discontinued and then restarted incrementally to 4 cm. Data were analyzed with a linear mixed-effects model, using random intercepts for individual pigs. Results: Upon cessation of AD during AHUP-CPR, decompression right atrial pressure (+59%) increased (p < 0.01), whereas multiple hemodynamic parameters positively associated with perfusion, including coronary (-25%)- 25%) and cerebral perfusion pressures (-11%),- 11%), end-tidal CO2 (-13%),- 13%), stroke volume and cardiac output (-26%),- 26%), decreased immediately and significantly with p < 0.05. Restoration of AD reduced right atrial pressure and increased positive perfusion parameters in an incremental manner. Only with >= 3 cm of AD were all hemodynamic parameters restored to >= 90% of pre-AD discontinuation levels. Conclusion: Full chest wall lift, achieved with >= 3 cm of AD, was needed to maintain and optimize hemodynamics during AHUP-CPR in pigs. These findings should be considered when optimizing care with this new approach.