DTR27BZ02-NV004 — Validation and Verification of Computational Modeling of Human Blast Injury on Battlefield

Computational modeling and simulation of human blast injury on the battlefield has been a gap for the Department of War (DoW). DTRA Technical Reachback is tasked with supporting operational decision-making by providing advanced analytics, modeling, and simulation. The Command Surgeon General Office has submitted numerous requests to estimate human blast injuries on the battlefield to inform medical planning purposes—specifically to forecast requirements for medical supplies, medical staff, and personal protective equipment (PPE). Furthermore, Combatant Commanders require assessment of casualty tolerance thresholds for specific operation environments. To address these analytics requirements, Technical Reachback initiated and continued a human blast injury modeling effort in the past three years. As development is ongoing, it is crucial to integrate the verification and validation effort early during the data collection and model development stage to ensure sound technical approaches, data application, and expected outputs.

Blast events accounted for over 70% of casualties among service members engaged in ground combat events. The energy generated by an explosion can cause devastating physical trauma, affect multiple body systems and result in severe injuries or even fatalities (1.2). Although there has been extensive research into injury mechanisms of blast trauma, including primary overpressure effects, secondary fragmentation wounds, tertiary blunt trauma, and quaternary thermal or chemical injuries, there are no modeling & simulation (M&S) tools currently available which can provide a comprehensive view of the types and severity of injuries in the context of the uncertainties and complexities of realistic battlefield scenarios. Existing injury modeling tools, such as Operational Requirements-based Casualty Assessment model (ORCA) developed by US Army DEVCOM, the INJURY code developed by the Medical Research and Development Command, and the AUDITORY model developed by the Joint Intermediate Force Capabilities Office (JIFCO), each model individual injuries occurring to a single person in the absence of PPE. They are not designed to address multiple, multi-modal injuries that may occur in ground combat, and they model wounds from the “skin in,” rather than accounting for the effects of clothing or PPE. These tools can only be used for research purposes and are not designed to support battlefield operation. In contrast, the Human Injury Prediction (HIP) tool, developed by Defense Science and Technology Laboratory (DSTL) of United Kingdom, predicts injuries to multiple people from a terrorist attack. Unfortunately, this tool is limited to modeling the effects of only a single blast event caused by a terrorist weapon detonated in an urban environment. And, again, HIP models isolated injuries and cannot address multiple, multi-modal injuries. Finally, a major challenge of leveraging these tools in DTRA Technical Reachback mission is that injuries are predicted based upon biomechanical effects, and do not address human physiology. This shortcoming becomes particularly critical with multiple injuries, where the human body response to injuries is intact and synergetic among organs/tissues. Apart from the specific challenges of modeling injuries and the associated changes in physiology, a comprehensive battlefield blast injury M&S tool is a multidisciplinary endeavor, requiring expertise in diverse domains, to include medicine, military operations, weaponeering, synthetic population modeling, epidemiology, structures, machine learning, computational modeling, and PPE. ASME V&V 40 serves as the gold standard for computational model credibility in biomedical applications, and DoD Instruction 5000.61 (Modeling and Simulation Verification, Validation, and Accreditation) requires human injury models to be validated before moving to support military operation (3,4,5). The modeling effort should align with the Blast Injury Research Coordinating Office (BIRCO) and the Blast Injury Prevention Standards Recommendation (BIPSR) process. The access to sensitive battle databases must be tightly controlled and limited to need-to-know personnel (6). Based on the regulation and scientific merit, the current request for proposal (RFP) will focus on validation of the on-going approach by using independent groups.

Phase I will focus on establishing standards to validate the current technical approach, data source, computational codes, medical definition, injury codes, environmental conditions (topography), generic weapon information and synthetic population. The offeror should thoroughly study all available injury modeling tools and provide detailed pros and cons summary for the existing methodologies (1.7,8). The contractor shall conduct a comprehensive review of pathophysiology of blast injuries and the established injury codes. Key validation methods shall be established. Due to complexity of the effort, machine learning is highly encouraged. A key requirement in this phase is delineation of where existing or synthetic data (based upon first principles modeling) may suffice, as compared to where laboratory or field testing will be required. By the end of Phase I, the offeror should deliver a preliminary approach and document all technical challenges for phase II work.

The validation methods proposed in Phase I should be applied in Phase II. Data sources from historical shock tube experiments, postmortem human surrogates (PMHS) testing, anthropomorphic test devices (ATDs) and computational models must be clearly identified and studied. Key challenges, such as material data gaps, incomplete injury criteria, military operational requirements and emerging weapons should be addressed in Phase II. The focus of this phase will be aggregating existing data and generating synthetic data. Test plans developed to fill in remaining gaps will be executed in Phase III. Key deliverables include but are not limited to: A structured database of pre-existing data used in validation, and associated data cards. A list of common data elements (CDEs) associated with the database of pre-existing data. This list should be forward-looking in that if many CDEs were not collected in the historical data, they would be recommended for inclusion in future data collection efforts. A structured database of synthetic data and associated data cards used in validation, along with detailed documentation of assumptions to include (1) loading conditions; (2) material properties; (3) tissue/human body models; and (4) first principal codes. This information should be sufficient for a third party to replicate analyses. Detailed test plans with test protocols suitable for submission to IACUC/IRB authorities.

In Phase III, the offeror will focus on the continued refinement and execution of the validation approach. This will primarily include execution of one or more test plans prepared in Phase II. In addition, the performer will have a strategy for ensuring that databases developed in Phase II are accessible to the broader DoW community, with mechanisms for integrating the latest research findings. The performer will work closely with the Blast Injury M&S team to recommend and evaluate changes to the models based upon validation findings. Finally, because new weapons or operational conditions may expand the ranges over which validation data is needed, ongoing collaboration with military medical professionals and other stakeholders is required.