Abstract Text: Title: AN MRDC-FUNDED COMBO SENSOR MONITORS BLAST AND BLUNT FORCES IN ACTIVE DUTY MILITARY SERVICE MEMBERS
Introduction: This paper summarizes new data aggregated from the past few years of a DoD-funded project (W81XWH-17-1-0019) aimed at accurately and precisely monitoring head impacts across a variety of military training activities, including military service academy athletics, parachute and combatives. This abstract also summarizes data acquired from a new blast force monitoring combo sensor, built on the same hardware and software platform. The blast data presented summarize the sensor response versus gold standard overpressure and acoustic sensors. Two parameters were of importance in this evaluation: the magnitude and the number of events that can be easily translated as the rate of exposure per hour for several military training environments. Materials/
Methods: A lab-calibrated impact monitoring mouthguard system, along with video and hardware to confirm the sensor was on the teeth during collisions, was used to acquire 22,540 head acceleration events (HAE) in 378 subjects over 1,375 subject-days involved in military training.
Results: There were 4,808 head impacts (21% of HAE) measured with peak linear acceleration (PLA) >10g, and 17,732 low-g events (79% of HAE) in the range of activities of daily living < 10g PLA. The median head impact was 14g PLA and 3J Workload. There was n=21 impacts between 50g and 100g PLA (0.04%). A total of n=14 ‘check engine’ impacts, when a subject had at least one visible concussion sign, were observed. Clinical information was available for six (6) of these impacts, and all were concussions. The combo blast sensor was used in military training environments to determine whether it could be used to quantify two key overpressure exposure parameters: 1) the number of exposures (count), and 2) overpressure magnitudes (peaks). The sensor system was also compared to gold standard reference probes on a military rifle range. A total of 1,893 overpressure exposures were measured in the analysis, and the peak overpressure was in the range of 0.1 psi to 10 psi across breaching, close quarters tactics (CQT) and weapons training.
Conclusions: Nearly 80% of HAE in military training, including static line parachute openings and much of combatives and athletics training, involves a PLA < 10g, on par with trampolining or having a pillow fight. This study also clearly shows a strong correlation between the top 1% of head impacts, ‘check engine’ behavior, concussion signs, and diagnosed concussions in military training. The combo sensor was found to have an omnidirectional response to overpressure and counted 100% of overpressures versus audio-recordings on the rifle range, breaching, and CQT shoot-house environments. As measured on the rifle range at the reference probe location (~1 m from firing position #1), the 0.50 caliber weapon produced 37 overpressure events during 14 minutes in the range of 4.6 to 8.8 psi reference. Based on acoustic recordings and measures from the modified hardware mounted at the reference location, there were a total of 144 rounds fired over 46 minutes from four (4) firing locations that generated reference overpressures ranging from 0.2 to 8.8 psi. For breaching instructors who wore the modified hardware alongside audio recordings to verify timing of overpressure events, they sustained an estimated 1-2 overpressure events per hour greater than 4 psi, up to 100 overpressure events per hour between 1 to 4 psi and up to 168 overpressure events per hour less than 1 psi based on calibrated output from the modified sensor. The MRDC-funded combo sensor system could be used in real-time to monitor blast and blunt force dosing across DoD training sites with automated reporting being delivered to Unit Commanders and Unit Clinical Staff support. Outliers in the data – e.g., high daily/hourly exposure dosing – can be made known and referred for an assessment when warranted by exposure. This evidence-based precision care may enhance mission readiness.
