Abstract 255: CT Imaging of Pediatric Heart Deformation During Chest Compressions

Abstract

Background: Adequate chest compression (CC) depth is associated with increased survival to hospital discharge, yet specific data guiding CC depth targets in children are lacking. Current guidelines for pediatric CCs are based on extrapolation from adults, animal models, and expert consensus. Given this lack of data, investigation into the biomechanical effect of CCs on the pediatric thorax is warranted. Methods: Three non-injurious CC simulations were performed on a single 7 year-old post-mortem human subject with intended compression depth of 0%, 15%, and 25% of external thoracic depth. A Phillips CPR Force Deflection Sensor replica was positioned at the inter-nipple line of the subject. Force was statically applied to reach the desired compression depth. Non contrast-enhanced CT imaging was obtained for each compression level. External thoracic depths were measured at the inter-nipple level from the most anterior to most posterior skin surface at midline. Internal depths were measured from the posterior sternal border to the anterior border of the corresponding vertebral body. Left ventricular volumes were calculated using three-dimensional multiplanar reconstruction and a 4-level modified Simpson method. Results: Intended 25% compression resulted in change of 25mm in external chest depth and 20mm of internal depth (a 16.4% and 29.6% change, respectively). Total left ventricular volume (inclusive of myocardium and ventricular cavity) was reduced by 8.8% (62.7cm 3 to 57.2cm 3 ). Right ventricular volumes were not measured due to difficulty in right heart border visualization, but subjective deformation of the right heart was greater than left. Conclusions: This is the first reported CT visualization of thoracic contents during compression of the pediatric chest. Our results indicate a proportionally greater decrease in internal thoracic depth than external depth for a given compression depth. Previous studies extrapolating the desired compression depth from CT-data have assumed internal compression directly proportional to external compression depth. These studies may overestimate the target depth necessary to achieve a given amount of internal thoracic compression.