Left Ventricular Compressions Improve Hemodynamics in a Swine Model of Out-of-Hospital Cardiac Arrest

Abstract

Introduction: We hypothesized that chest compressions located directly over the left ventricle (LV) would improve hemodynamics, including coronary perfusion pressure (CPP), and return of spontaneous circulation (ROSC) in a swine model of cardiac arrest.

Methods: Transthoracic echocardiography (echo) was used to mark the location of the aortic root and the center of the left ventricle on animals (n = 26) which were randomized to receive chest compressions in one of the two locations. After a period of ten minutes of ventricular fibrillation, basic life support (BLS) with mechanical cardiopulmonary resuscitation (CPR) was initiated and performed for ten minutes followed by advanced cardiac life support (ACLS) for an additional ten minutes. During BLS the area of maximal compression was verified using transesophageal echo. CPP and other hemodynamic variables were averaged every two minutes.

Results: Mean CPP was not significantly higher in the LV group during all time intervals of resuscitation; mean CPP was significantly higher in the LV group during the 12-14 minute interval of BLS and during minutes 22-30 of ACLS (p < 0.05). Aortic systolic and diastolic pressures, right atrial systolic pressures, and end-tidal CO2 (ETCO2) were higher in the LV group during all time intervals of resuscitation (p < 0.05). Nine of the left ventricle group (69%) achieved ROSC and survived to 60 minutes compared to zero of the aortic root group (p < 0.001).

Conclusions: In our swine model of cardiac arrest, chest compressions over the left ventricle improved hemodynamics and resulted in a greater proportion of animals with ROSC and survival to 60 minutes.

Keywords: cardiopulmonary resuscitation; echocardiography; hemodynamics; perfusion; survival.