Anthony J. Karis

Acceptability of a Wearable Vital Sign Detection System

This study assessed the human factors issues associated with wearing a Vital Sign Detection System (VSDS), a body worn physiological monitoring system. Experienced combat Soldiers (n = 27) participated in a combat training exercise of ∼ 120 hr while wearing the VSDS. They were then given a questionnaire to assess comfort, physical impact on the body, and acceptability of the VSDS as well as questions on fit, impact on performance, and durability of the VSDS. Comfort was impacted the most by the VSDS when in the prone position, possibly affecting sleep, and prone position rifle shooting. Skin irritation or discomfort was reported in 85% of respondents. Sixty-two percent thought the VSDS was not acceptable to wear for ≥ 8 hr. Yet, at the same time, 92% of Soldiers approved of the concept for health monitoring, and 89% said they would wear the VSDS as is if it could help save their life. The VSDS needs to be modified to be more comfortable before it can be fielded for medical monitoring of Soldiers in the field.

Acceptability and Usability of an Ambulatory Health Monitoring System for Use by Military Personnel

OCCUPATIONAL APPLICATIONS A physiological status monitoring system was evaluated for use by soldiers in the field. Two different designs were evaluated, with the design based on previous human factors evaluations proven to be more comfortable and acceptable for use. This study demonstrated that the advanced design of the EQ-02 physiological status monitoring system met dismounted soldier needs. Furthermore, this study validated the use of a usability evaluation in the successful design/advancement of a physiological status monitoring system. TECHNICAL ABSTRACT Background: Previous research has shown that the form factor of a physiological status monitoring system, the Equivital™ EQ-01 (Hidalgo Ltd., Cambridge, UK) had problems associated with comfort and usability of the system for soldiers. Previous data gathered was used to guide improvements in the physiological status monitoring system. Purpose: Assess whether the previous feedback from usability evaluations helped guide improvements in comfort, acceptability, and usability of a physiological status monitoring system for dismounted soldiers. Improvements to the EQ-01 system were incorporated into the next-generation EQ-02 (Hidalgo Ltd., Cambridge, UK) system. Methods: Thirty-nine infantry dismounted soldiers were randomly assigned to wear either an EQ-01 or EQ-02 system while performing standard military field training. They filled out a survey on fit, comfort, irritation to the body, impact on military performance, and acceptability. They then wore the other system and filled out the same survey. Results: The Equivital™ EQ-02 system was superior in terms of fit (51% better in overall fit), ease of donning (10% easier), comfort (45% more comfortable), impact on military performance (45% less impact), impact on the body (17% less impact), and acceptability (32% more acceptable). All these measures are subjective self-report ratings. Conclusions: A human factors engineering approach provided an effective means of guiding improvements and the production of a physiological status monitoring system that dismounted soldiers were more likely to accept and wear.

Biophysical Assessment and Predicted Thermophysiologic Effects of Body Armor

Introduction Military personnel are often required to wear ballistic protection in order to defend against enemies. However, this added protection increases mass carried and imposes additional thermal burden on the individual. Body armor (BA) is known to reduce combat casualties, but the effects of BA mass and insulation on the physical performance of soldiers are less well documented. Until recently, the emphasis has been increasing personal protection, with little consideration of the adverse impacts on human performance. Objective The purpose of this work was to use sweating thermal manikin and mathematical modeling techniques to quantify the tradeoff between increased BA protection, the accompanying mass, and thermal effects on human performance. Methods Using a sweating thermal manikin, total insulation (IT, clo) and vapor permeability indexes (im) were measured for a baseline clothing ensemble with and without one of seven increasingly protective U.S. Army BA configurations. Using mathematical modeling, predictions were made of thermal impact on humans wearing each configuration while working in hot/dry (desert), hot/humid (jungle), and temperate environmental conditions. Results In nearly still air (0.4 m/s), IT ranged from 1.57 to 1.63 clo and im from 0.35 to 0.42 for the seven BA conditions, compared to IT and im values of 1.37 clo and 0.45 respectively, for the baseline condition (no BA). Conclusion Biophysical assessments and predictive modeling show a quantifiable relationship exists among increased protection and increased thermal burden and decreased work capacity. This approach enables quantitative analysis of the tradeoffs between ballistic protection, thermal-work strain, and physical work performance.

Effect of WBGT Index Measurement Location on Heat Stress Category Classification.

UNLABELLED The location of the wet bulb globe temperature (WBGT) index measurement may affect heat stress flag category classification. PURPOSE This study aimed to compare WBGT measurements at three locations along the Boston Marathon race course and compare WBGT estimates for meteorological stations and 72-h advanced WBGT forecasts. METHODS WBGT was measured hourly from 1000 to 1400 h at approximately 7 km, approximately 18 km, and approximately 30 km on the Boston Marathon race course. Simultaneous WBGT estimates were made for two meteorological stations southeast of the course via a commercial online system, which also provided 72-h advanced forecasts. RESULTS The measurement difference (mean ± SD) among course locations was 0.2°C ± 1.8°C WBGT (ANOVA, P > 0.05). The difference between course and stations was 1.9°C ± 2.4°C WBGT (t-test, P < 0.05). Station values underestimated (n = 98) or overestimated (n = 13) course values by >3°C WBGT (>0.5 flag category) in 111 of 245 paired comparisons (45%). Higher black globe and lower wet bulb temperatures explained over- and underestimates, respectively. Significant underestimates of WBGT resulted in misclassification of green (labeled white) and black (labeled red) course flag categories (χ2, P < 0.05). Forecast data significantly underestimated red (labeled amber) and black (labeled red) course flag categories. CONCLUSIONS Differences in WBGT index along 23 km of the Boston Marathon race route can be small enough to warrant single measurements. However, significant misclassification of flag categories occurred using WBGT estimates for meteorological stations; thus, local measurements are preferred. If the relation between station WBGT forecasts and the race sites can be established, the forecast WBGT values could be corrected to give advanced warning of approximate flag conditions. Similar work is proposed for other venues to improve heat stress monitoring.

Thermal-work strain in law enforcement personnel during chemical, biological, radiological, and nuclear (CBRN) training

Abstract Background: Thermal safety standards for the use of chemical, biological, radiological, and nuclear (CBRN) ensembles have been established for various US occupations, but not for law enforcement personnel. Objectives: We examined thermal strain levels of 30 male US law enforcement personnel who participated in CBRN field training in Arizona, Florida, and Massachusetts. Methods: Physiological responses were examined using unobtrusive heart rate (HR) monitors and a simple thermoregulatory model to predict core temperature (Tc) using HR and environment. Results: Thermal strain levels varied by environments, activity levels, and type of CBRN ensemble. Arizona and Florida volunteers working in hot-dry and hot-humid environment indicated high heat strain (predicted max Tc>38·5°C). The cool environment of Massachusetts reduced thermal strain although thermal strains were occasionally moderate. Conclusions: The non-invasive method of using physiological monitoring and thermoregulatory modeling could improve law enforcement mission to reduce the risk of heat illness or injury.

Cardiorespiratory responses to heavy military load carriage over complex terrain

This study examined complex terrain march performance and cardiorespiratory responses when carrying different Soldier loads. Nine active duty military personnel (age, 21 ± 3 yr; height, 1.72 ± 0.07 m; body mass (BM), 83.4 ± 12.9 kg) attended two test visits during which they completed consecutive laps around a 2.5-km mixed terrain course with either a fighting load (30% BM) or an approach load (45% BM). Respiratory rate and heart rate data were collected using physiological status monitors. Training impulse (TRIMP) scores were calculated using Banisters formula to provide an integrated measure of both time and cardiorespiratory demands. Completion times were not significantly different between the fighting and approach loads for either Lap 1 (p = 0.38) or Lap 2 (p = 0.09). Respiration rate was not significantly higher with the approach load than the fighting load during Lap 1 (p = 0.17) but was significantly higher for Lap 2 (p = 0.04). However, heart rate was significantly higher with the approach load versus the fighting load during both Lap 1 (p = 0.03) and Lap 2 (p = 0.04). Furthermore, TRIMP was significantly greater with the approach load versus the fighting load during both Lap 1 (p = 0.02) and Lap 2 (p = 0.02). Trained military personnel can maintain similar pacing while carrying either fighting or approach loads during short mixed terrain marches. However, cardiorespiratory demands are greatly elevated with the approach load and will likely continue to rise during longer distance marches.