Abstract 222: Real Time Feedback of Chest Compressions by Hands-Free Carotid Doppler in a Porcine Model

Abstract

Background: Real-time hemodynamic feedback devices provide information on cardiopulmonary resuscitation (CPR) quality. This can improve hand positioning and technique, thereby maximizing blood flow and potentially improve survival. Hypothesis: We hypothesize that a newly developed hands-free Doppler for carotid blood flow velocity (RescueDoppler, RD), can identify optimal vs. suboptimal chest compression sites during CPR. Aim: To assess the potential of the RD device to continuously monitor the effect of each compression by ultrasound metrics and waveforms in a porcine model. Methods: Ventricular fibrillation was induced in 5 pigs using an ICD. Manual CPR (blinded for hemodynamic data) was performed for 10 seconds at 3 different compression sites in random order (Fig.), and repeated 6 times. We analyzed ultrasound waveforms with Time Average Velocity (TAV) in a linear mixed model with site as fixed effect, and animal and site within animal as random effects. We further compared TAV to invasive systolic blood pressure (SBP) from the contralateral carotid artery. Results: Data from 5 pigs (mean weight 31.2 kg) and 29 of 30 sequences were included. Overall, blood flow velocity was highest at compression site 2 (TAV 33 cm/s, P<0.01), but there was significant variability (P<0.01) in animals (SD= 3.7) and at sites within animal (SD= 7). A compression site yielding the highest TAV (range 19 to 48 cm/s) or lowest TAV (6-25 cm/s) was successfully identified in all animals with corresponding SBPs 50-81 mmHg, and 46-64 mmHg, respectively. The correlation between TAV and SBP was 0.62-0.90 within animals. Conclusions In this animal study, a newly developed hands-free Doppler enabled assessment of blood flow velocity during CPR and detected significant variation according to chest compression site. RD identified the sites with both high and low blood flow velocities and is thus a promising device for effectively identifying the optimal and suboptimal chest compression sites during CPR.