Abstract 267: Airway Pressure Is a Valid Surrogate for Intrapleural Pressure During CPR

Abstract

Background: Using direct measurement of intrapleural pressure (Ppl), we sought to assess true intrathoracic pressure during various interventions of CPR and to explore its relationship with airway pressure (Paw). We hypothesized that Ppl would correlate with Paw and with coronary (CPP) and cerebral (CePP) perfusion pressures. Methods: Ppl catheter was inserted into right anterior aspect of pleural cavity. Paw, right atrial (Pra), aortic and intracranial (ICP) pressures were recorded continuously. Proper placements were confirmed in all animals post mortem. Following 4 minutes of untreated ventricular fibrillation in 6 anesthetized female farm pigs (34 ± 2 kg), CPR was performed in the following sequence for 2 minutes per each intervention. Standard CPR (sCPR), Active compression decompression (ACD) CPR, ACD+ inspiratory impedance threshold device (ITD) CPR, ACD + intrathoracic pressure regulator (ITPR) CPR. Data were collected during last 20 seconds of each intervention. Results: Highest and lowest mean Paw and Ppl were observed during sCPR and ACD +ITPR CPR respectively. Mean Paw showed modest correlation with mean Ppl. (r2=0.15, p=0.06). After adjusting for variance between the animals, significant correlation was observed (r 2 =0.81, p<0.0001). In contrary, no significant correlation was observed between mean Pra and Ppl. Among intrathoracic pressure variables mean Ppl and Paw (not mean Pra) showed significant inverse correlations with both CPP and CePP. Mean Pra was strongly correlated with ICP. (Table) Conclusion: A significant correlation of mean Paw with Ppl provides validity of using Paw as a surrogate measurement to monitor intrathoracic pressure during standard CPR and ACD assisted interventions. Table) Within animal correlation between intrathoracic pressure variables and central perfusion pressures.