Abstract 39: Adequate Tidal Volumes and Improved Survival With Continuous Chest Compressions and Synchronized Ventilation (10:1)
Background: Compression pauses are recommended with non-invasive ventilation during cardiac arrest to allow adequate tidal volume (VT) and minimize gastric insufflation. These pauses are associated with a rapid decline in cardiac output. Prior studies may not have considered the impact of chest recoil, which may preferentially divert air into the lungs.
Methods: In May 2006, our EMS protocols changed from standard AHA guidelines to continuous chest compressions with synchronized ventilations (10:1 ratio) during both BVM ventilation and following endotracheal intubation (ETI). A convenience sample of cardiac arrest victims was used to evaluate the adequacy of BVM as compared to ETI ventilation. PetCO2 values immediately before (BVM) and after ETI were abstracted using code review software and audio recordings. PetCO2 values recorded immediately prior to compression pauses (following 2 min CPR) were used for standardization. A mathematical model was derived incorporating PaCO2, PetCO2, dead space volume (VD), and tidal volume (VT) for both BVM and ETI ventilation. Various input values for ETI VT (200–500 mL), ETI PaCO2 (40–60 mmHg), and the BVM-to-ETI PaCO2 difference (0–10 mmHg) were modeled. An additional VD of 58.1 mL with use of BVM was assumed. Predicted values for BVM VT and ETI VT were compared across all input values for ETI VT. Electronic PCR's were abstracted for complications. Survival to ED admission before and after the protocol change was compared.
Results: A total of 56 patients were included in the main analysis. Mean pre-pause PetCO2 values were 24.1 mmHg for BVM and 29.5 mmHg for ETI. Predicted VT with BVM ventilation ranged from 26.9% lower to 33.5% higher than VT with ETI ventilation, depending on the model input values. No clinically significant episodes of regurgitation were reported. Survival to ED admission improved from 9.7% (n=982) to 12.2% (n=3395, p=0.035) with implementation of this ventilation protocol.
Conclusions: Synchronized ventilation (10:1) with BVM during continuous chest compressions appears to provide adequate tidal volumes. Gastric insufflation with regurgitation did not appear to be a clinically significant concern. Improved short-term survival rates were observed when compared to interrupted compressions.
- © 2010 by American Heart Association, Inc.