Abstract 415: Standard versus Early Abdominal Counter-Constriction During Circumferential CPR

Introduction: Circumferential constriction CPR (CC-CPR) applied by pneumatic vest may be superior to standard sternal compression, and the addition of alternative pumping modalities may further enhance efficacy. Interposed abdominal counterpulsation (IAC-CPR) CC-CPR is one such modality. Early canine studies of IAC reported greater efficacy when the abdominal counterpulsation was started 30% before the thoracic compression, rather than fully counterphase timing as is used clinically. This may be thought of as “Abdominal Preload” IAC (Pre-CPR). Hypothesis: Addition of IAC-CPR to CC-CPR may be associated with improved perfusion pressures, and Pre-CPR may be even more effective. Methods: We compared CC-CPR to IAC-CPR and Pre-IAC in a porcine model of VF (n=6). In IAC-CPR, the constrictions are fully counterphase. In Pre-IAC, abdominal constriction is initiated 30% before thoracic constriction. Alternating 30 second epochs of each treatment were applied via a circumferential abdominal vest. Aortic (Ao) and Right Atrial (RA) pressures were measured by micromanometer catheters. IAC-CPR and Pre-CPR end-epoch pressures were each compared to preceding CC-CPR end-epoch pressures. Results: Addition of IAC-CPR and Pre-IAC to CC-CPR were both associated with similar, significant increases in CPPs. However, the source of these improvements differed (See Table 1). For IAC-CPR, the increase appeared to result from an Ao increase greater than an associated increase in RA. For Pre-CPR, the increase appeared to be solely due to increased Ao. Limitations: Small sample. Surrogate biomarkers. Non-human model. Conclusions: The addition of pulsatile abdominal counter-constriction to vest CC-CPR may be a promising path to multimodality, regardless of the particulars of cycle timing. We do not confirm earlier observations that Pre-CPR may be superior to IAC-CPR.