Access Type

Open Access Dissertation

Date of Award

January 2011

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Biomedical Engineering

First Advisor

Cynthia A. Bir

Abstract

Commotio Cordis (CC) has proven to be life threatening for young athletes as it is the second leading cause of mortality in youth sports. In the past 15 years, researchers have been working to understand the pathophysiology of this event. It has been proven that impacts directly over the cardiac silhouette during a vulnerable period of the cardiac cycle can cause CC. In order to reduce the occurrence of CC in sports, chest protectors need to be tested for efficacy. Currently there is no biofidelic surrogate to serve this purpose. In order to test equipment to a given standard of protection, a biomechanical surrogate is needed that models the human response to impacts observed in sports. The goal of this dissertation was to develop and validate a biomechanical surrogate that can predict the risk of CC.

The first step in developing a biomechanical surrogate is the identification of an effective injury criterion that can predict the injury outcome. Porcine specimens were impacted directly over the heart during the vulnerable portion of their cardiac cycle. Impacts were conducted with a lacrosse ball at four speeds that have been proven effective to induce CC in a porcine model (30, 40, 50, and 60mph). Ten injury criteria were evaluated, and impact force proved to be the most effective injury criterion (Somer's D = 0.52).

Human response corridors were developed for the same impact conditions using Post Mortem Human Specimens (PMHS). These data were used to evaluate existing thoracic biomechanical surrogates. Three surrogates were tested in the same impact conditions and none were found to be biofidelic (Biofidelity Rank > 2). A new Sports Specific Thoracic Surrogate (SSTS) was developed and validated using the human response corridors (Biofidelity Rank = 1.2). The SSTS was used to evaluate 70 lacrosse chest protectors from ten (10) manufacturers. These data provided a broad survey of the current level of CC protection commercially available. A statistical analysis was conducted on ten (10) pieces of equipment from seven of the manufacturers. All of the equipment proved to be effective in limiting impact force and reducing the risk of CC. Equipment efficacy could be improved by utilizing this surrogate as a development tool to evaluate new chest protector designs. It could also be used in certification testing by an organization such as National Operating Committee on Standards for Athletic Equipment (NOCSAE). The development of a NOCSAE certification standard would encourage manufacturers to improve the CC protection offered.

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