Abstract 103: Chest Deformation During CPR
Introduction: Volume changes in the thorax cavity due to chest compressions generate pressures and flows. Overly deep compressions, however, can lead to severe injury and may have an intrinsic, negative, impact on the ability to generate cardiac output. It is important to understand the reaction of the anterior and lateral chest walls to these forces. These deformations are only minimally described in literature and include rotation and, lateral wall movement.
Methods: Thorax Measurement Devices (TMD's) were placed on the chests of 21 patients and recorded chest displacement and angle. TMD1 measured compression depth and angle, TMD2 was used for lateral thorax deflection. TMD3 was used to remove the mattress compression that was recorded by TMD1. Force was simultaneous measured with The Philips HeartStart MRX QCPR pad. Thorax (starting) angles, lateral thorax deflection and compression force were studied and are presented as mean ± SD. Figure: Lateral and cranial view of TMD placement. α is the thorax angle, X is the lateral thorax excursion , Z1-Z2 is the compression depth.
Results: CPR was carried out with a compression depth of 4.7 ± 0.8 cm and a force of 534 ± 100 N. The starting angle was 6.5 ± 8.7 degrees. The compressed arc was 6.6 ± 2.2 degrees lower than the starting angle. The lateral thorax deflection was 1.5 ± 0.5cm
Conclusions: The sternal angle started at a slight positive value and became more negative during CPR, sometimes reaching a negative angle. The compression depth can be partly explained by this rotation, the other part can be explained by pure vertical displacement. There lateral wall moves a significant amount w.r.t. the compression depth.
- © 2010 by American Heart Association, Inc.