Casualty Safe Ride Standards: A Study of Ride-induced Blood Clot Dislodgement
Abstract
During transport from the battlefield to the field hospital casualties are subject to various forces. Potential risks due to these f,orces are largely unknown, but may include exacerbating injuries sustained in the theater. Therefore, safe ride standards should be,established that limit these forces to safe physiological limits. In our work, we submit that one potential transport risk is transp,ort-induced dislodgement of blood clot from the site of injury; thus, leading to deadly sequalae such as heart attacks, strokes, and, pulmonary embolisms. The objective of this work is to determine safety standards for transport of casualties based on risk of blood, clot dislodgement. To this end, we will answer the scientific question of what is the primary mechanism of blood clot dislodgement,during casualty transport and what are the conditions at which this dislodgement occurs? To answer this question our study will focu,s on the two most likely dislodgement scenarios: (1) interfacial failure between the clot and the blood vessel wall, and (2) bulk fa,ilure by which a part of the clot detaches. To evaluate loading conditions that are representative of casualty transport, we will co,nsider both static loading and dynamic loading to determine the supercritical, acute forces for failure, and to determine the recurr,ent sub-critical forces for fatigue failure, respectively. Three different loading modes will be investigated to induce different fa,ilure mechanisms: normal force (mode-I), shear force (mode-II), and cavity expansion. To quantify the failure loading amplitudes and, cycles for each mechanism and mode, and to identify the most likely mechanism/mode pair to drive clot dislodgement during transport,, we will (1) test coagulated in-vitro blood clot samples for their interfacial fracture properties under shear, normal loading, and, cavity expansion to establish classic stress-cycle number curve (i.e., SN-curves) for each loading mode, and (2) test coagulated b,lood samples for their bulk fracture properties under shear, normal loading, and cavity expansion. Here, again, we will establish cl,assic SN-curves for each loading mode. The collaborative team consists of Dr. Rausch at the University of Texas at Austin and Dr. Co,hen at Massachusetts Institute of Technology. We will combine our significant previous experience to conduct above experiments. Spec,ifically, Dr. Rausch will conduct classic mode-I/II fracture experiments, while Dr. Cohen will conduct their innovative cavity expan,sion technique. Applying these methods independently will allow for validation of our results and mitigation of scientific risks. Up,on successful conclusion of our experiments and analyses, we will have established a clear understanding for the conditions under wh,ich blood clot fails via fracture. That is, we will know at what load and repetition cycles blood clots fail under normal stress (mo,de-I) and shear stress (mode-II) and whether they fail in the bulk or at the interface. We willhave validated these findings with an, independent experiment (viz. cavity expansion experiments). These data will be a critical step toward establishing safe ride standa,rds and thereby impact the DoDs ability by allowing to improve and optimize casualty transport. Approved for Public Release
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 05, 2022
- Source ID
- N000142212073
Entities
People
- Manuel K Rausch
Organizations
- Office of Naval Research
- United States Navy
- University of Texas at Austin