Outflow Tract Patency and Ventricular Compression as Determinants of Cardiopulmonary Resuscitation Hemodynamics in a
Felipe Teran1, Clark G Owyang2, Manuel Martin-Flores3
1Translational Resuscitation Sciences Laboratory, Department of Emergency Medicine, Weill Cornell Medicine, New York Presbyterian Hospital, New York, New York.
Background:
Perioperative cardiac arrest carries high mortality. Standard landmark-guided chest compressions frequently overlie the left ventricular outflow tract (LVOT). In the operating room, transesophageal echocardiography (TEE) can guide compression location in real time. Because LVOT-centered compressions may narrow the outflow tract and reduce direct left ventricle compression, This study hypothesized that continuous intra-arrest TEE guidance to maintain mid-left ventricle compressions would improve hemodynamics versus LVOT-centered compressions.
Methods:
In a swine model, ventricular fibrillation was induced and followed by 10 min of basic life support. Continuous midesophageal long-axis TEE was used to randomly deliver chest compressions over the mid-left ventricle (CC-LV, n = 8) or the LVOT (CC-LVOT, n = 5). The primary endpoint was coronary perfusion pressure (CPP). Secondary endpoints included end-tidal carbon dioxide (ET co2 ), left ventricle and right ventricle compression pressures (LVP and RVP), and systolic and diastolic aortic pressures. LVOT collapse was quantified with M-mode. Linear mixed-effects models were used to examine differences in hemodynamic endpoints between the CC-LV and the CC-LVOT groups after adjusting for baseline characteristics.
Results:
During resuscitation, after accounting for baseline imbalances between groups, CC-LV generated higher CPP than CC-LVOT (difference, 15.6 mmHg; 95% CI, 9.8 to 21.5), as well as higher systolic and diastolic aortic pressures (differences, 32.4 mmHg [95% CI, 12.9 to 51.9] and 11.3 mmHg [95% CI, 3.6 to 19.0], respectively), and higher LVP and RVP (differences, 82.4 mmHg [95% CI, 31.8 to 132.9] and 77.5 mmHg [95% CI, 17.7 to 137.3], respectively). ET co2 was also higher with CC-LV (difference, 11.9 mmHg; 95% CI, 3.0 to 20.7). LVOT collapse was greater with CC-LVOT (82% vs. 10%). LVOT collapse correlated with lower CPP, ET co2 , and aortic pressures, while LVP correlated positively with these variables.
Conclusions:
Continuous TEE-guided, left ventricle-targeted compressions preserved LVOT patency and improved intra-arrest hemodynamics. Correlations between LVOT collapse, left ventricle compression pressures, and perfusion variables suggest that differences between left ventricle and LVOT compressions reflect dynamic outflow tract narrowing and reduced ventricular compression.
