Ravan(e~ in .~- , -Un~erHan~ i n~ ~uman Performance neuroer~onomio, ~uman racton Deli~n , ana ~pecial Populationl .'

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Tadeu!Z mareK Waldemar Karwow~Ki

Valerie Rice

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REPOR" DOC UMENTATION PAGE F~_

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1. It!POAT OAT! (OO-N1rIo Y"r"YI? I 2.. JW>ORT TYPI!! r' DATES COVERED (From· To} 22-07-2010 Book Chapter 2009-2010

TTTU AND SU8T1TLE ra. CONTRACT HUMBER: The effects of a ehemicallbiolog cal protective wrap on simulated physiological responses of soldi !rs. F" GRAHT HUYSER In: Advances In Understanding I uman Performance: Neurocrgonomics, Human Factcn, Design. and Spe 'ial Populations. Marek. T., Karwowski. W., and Rice. V (Editors). Boca Rate 1. FL: CRC Press. Taylor and Francis pc. PROGRAM ELEMENT HUMBER Group. Pp 4S()..4S8 .

.. AUTHOR(S) ~ PROJECT ..... BEIl

Miyo Yokota. Thomas Endrusid. Julio Gonzalez.. and Donald MacLeod

~. TASK HUIIBER

, WORK UNIT HUMBER

7. PEftFOfUIIIHG ORGANIZATlOH HAME(S' AND ADORESSCES: I'- PERFOftMING OftGAHIZATlOf, REPORT HUYSER

BiophYSICS and Biomedical Mod :ling Division U.S. Anny Rcscrch Institute of E wironmcntal Medicine

MISC 10-18 Natick. MA 01760-5007

t. SPOHSORlNGlMONtTORlNG AGEHCY N "'E{S) AND ADORES5(ES: 10. SPONSORIIIOHtTOR'S ACROHYII{S)

U.S, Anny Medical Researeh am Materiel Command Ft. Detrick.

11. SPONSORIIIIOMTOR'S REPORT Frederick. MD 21702-5012 NUMBat(S)

12.. DIS1l!IIIU11ONIAVAll..ABll.ITY STATB eNT

Distnbuuon is Unlimited

11 SUPPl..DlleNTARY HOTES

14. ABSTRACT

This study used a thcrmorcgulatc 'Y model to examine the therm:ll burden imposed by a new U.S. Army protective patient wrap (PPW) design. The model simulltions were conducted for typical desert. jungle, and temperate conditions with and without direct sun. Five PPW configurat ons (the current baseline. and lamiated and non-laminated versions of the PPW with and without fan ventilation) were tested. Tht results suggested that soldiers would be likely to experience heat illness in < 6 hours when cxposed to direct sun light in all ;imulated environments. Shade is effective in delaying or preventing soldiers from becoming heat casualties.

15. SUtuECT TERMS

Protective patient wraps. heat str lin. modeling, Simulation. core temperature, U.S. Army. chemicallbiologlcal warfare, thermoregulatIOn

II. SECUA:ITY CLASSIFJCA TlON OF 17, LIMITATION OF 11. NUMBER ... NAME CW' RESP'OHSIIIU. PERSOH . """"" . ...."..." c.. 1liSPAGE ~ OF Miyo Yokoca 'AGES It.. ~ HOMBER(1ncJudrt __ Qt)

450

CHAPTER 46

The Effects of Chemical/Biological

Protective Patient Wraps on Simulated Physiological

Responses of Soldiers

Miyo Yokota', Thomas Endrusice, Julio GOflzale/, Donald MacLeoi

IUS Anny Research Institute of Environmental Medicine Natick MA 01760-5007, USA

IUS Arnly Natick Soldier Research Development and Engineering Center Natick, MA 01760-5007, USA

ABSTRACT

This study used a thermoregulatory model to examine the thermal burden imposed by a new U.S . Army protective patient wrap (PPW) design. The model simulations were conducted for typical desert, jungle, and temperate conditions with and without direct SUil . Five PPW configurations (the current baseline, and laminated and non-laminated versions of the PPW with and without fan ventilation) were tested _ The results suggested that soldiers would be likely to experience heat illness in < 6 hours when exposed to direct sun light in all simulated environments_ Shade is effective in delaying or preventing soldiers from becoming heat casualties.

Keywo rds: Protective patient wraps, heat strain, modeling, simulation, temperature, US AmlY, chemicallbiological warfare, thermoregulation

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451

INTRODUCTION

The protcctive p

452

on a cot elevated two feet above the ground. The metabolic rate of the patient associated with the condition was estimated to be 0.8 MET (-45W/m2) (ASHRAE 200!). The simulation of human physiological responses to PPW cncapSulatio~ were conducted for typical desert (T. : 49"C, RH: 20%), jungle (T.: 3S"C; RJ-l: 70%) and temperate (T.: 35"C; RH: 50%) conditions where deployed soldiers could

..eKpe1icncc heal related illness or impairment. The MRT for the shade or n

453

Table 1: Meteorological conditions used to simulate desert, jungle, and temperate environments

Environments

Parameters Desert Jungle Temperate

Ta °C(°F) 48.9 (120) 35.0 (95) 35.0 (95)

RH% 20 75 50

DP "C(°F) 20 (68) 30 (86) 23 (73) V m_s 1 (mph) 0.4 (0.89) 0.4 (0.89) 0.4 (0.89)

MRTs DC(°F) 68.9 (156) 55.0 (131) 55.0 (131)

MRTn °C(°F) 48.9 (120) 35.0 (95) 35.0 (95)

Ta: Air temperature, RH: Relative humidity; OP: Dew point; V: Wind speed; MRTs: Mean radianl temperature with fuJi sun; MRTn: Mean radiant

temperature with shade

RESULTS

Figure 3a-c summarizes the simulated To responses to the different prw configurations in the three environmental conditions with or without solar radiation. Overall, for the desert condi tion with and without solar radiation, T t rises 10 38.5 QC more quickly than other conditions. The simulations indicated that soldiers inside .PPW would be likcly to experience thermal strain (i.e., I'c > 3S.S°C) during the Ghl" c,'posure in all three climate conditions with the strain developing roughly 2S -SO% faster in the higher levcl.s of T. andfor RJ·!. [n al! three environmental conditions, patient s in al! of the PPWs had consistently lower To levels when located in thl' shade and could safely stay longer than when located in the sun. When the Simulated patients were located in a shaded desert or a sunny temperate condition, the fan-powered PPW ventilation system was very effective in helping individuals thermo-regulate, lowering their To responses and thus increasing PPW safe stay limes by about IS-30% compared to the non-ventilated PPW configurations (Figure 3a, 3c). The differences in Tc responses among the PPWs were small in other Conditions.

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456

Table 2: Tolerance lime (minutes) to reach core temperature of 38SC by protective patient wrap configuration and environmental condition with Or without solar load.

-Desert Jungle Temperate ConfigurationlSolar effect Solar Shade Solar Shade Solar S"""e CUrrent 66 178 93 >360 124 >360 Non-laminated + Fan-Off 64 177 91 :>360 123 >360 Non-Laminated + Fan-On 6B 223 96 >360 140 >360 Laminated + Fan.Qff 62 164 90 >360 117 >360 Laminated + Fan-On 6B 220 96 >360 139 >360

CONCLUSIONS

This study examined simulated Tc responses of heal acclimated soldiers who were fully encapsulated in a PPW during three different hot-warm cn\lironrl1enl~1 conditions. The simulations used 10 evaluate the different PPW configurations were based on realistic information regarding the subjects' anthropometries, metabolic rate, PPW biophysical characteristics, and environmental and system operational conditions. The results indicated that patients inside PPW would be likely experience thermal strain faster when T. and RH increasc. Further, the simulations indicated that shading from direct sun ·is critically important in delaying or preventing individuals from becoming heat casualties. The fan-powered PI'W ventilation syslem was effective only when they were lying under a shaded desert or sunny temperate condition. Otherwise, the diITercnees in To responses among tile PPWs were minimal Based on the current U.S. Army criterion [or PI'W encapsulation targeted time (Depurtment of Army, 1985), soldiers would be likely 10 experience heal illness in less than six hours when exposed to direct sun light in all simulated environments. Simulated patients, when shaded from solar exposure, could safely endure 6 hours only in the jungle and temperate environments. Thus, shade from direct sun is important in delaying and prcventing patients from becoming heat casualties.

The simulation used in this study was assumed to be an "avemge uninjured" soldier in the US Anny. The diffcrent somatic forms in a population as well as the patients' medical condition and treatment (Cadareue ct al., 1988; Stephenson et aI. , 1988; Yokota ct al., 2008; Bar-Or et al., 1969) could cause variability in physioiogiclil responses 10 the heat stress. For instance, obese individuals in walking in the heat respondcd to thermal strain wi th a morc rapid rise in To than lean individuals (Bar-Or et al., 1969; Shvarts ct al., 1973). A multivariate thermal

457

model simulation suggested similar results would be evident in soldiers walking and working on a simple Anny task (Yokoln cl aI., 2008). For another cx:!mplc, the usage of atropine as a common treatment to regulate putients' parasympathetic nervous system reduces their sweat rates, am! rapidly increases a patient's T< (Cmbrcttc ct aI., 1998; Stephenson ct aL, 1988). Importantly, medica l circumstances such as injury, loss of blood, and respiratory problems inside a PPW D1

458

Kraning, K" and Go~za1cz, R.(1997), ':A mech:lnisti~ con:pukr simulation of~uman wOrk HI heat that 'accounts for physical and physIOlogical effects of clothmg, aerobi fitness, and prob'Tessive dehydrat ion." Journal a/Thermal Biology. 22,33\ -342 . c

Matthew, W, Santee, W., and Berglund L. (2OCH), Solar load inputs ./01' USARJEM ther1llql .Hmin models and (he solar radiatIOn-sensitive components of the WBCr index Technical Report TO I- i3, USARJEM, Natick. '

Sawka, M, ... Latika, W" Monta in, S. et al. (2000), "Physiologic tolerance to uneompensable ,- neaL intemliltent exercise, field vs. laboratory." Medicine & Science in Sports &;

Exercise, 33,422-430, Shvarts, B:., Sarr, E., and Benor, D. (1973), "Physique and heat to lerance in hot-dry and hOl_

humid environments." Journal of Applied Physiology 34,799-803. Stephenson, L., Kolka, M., Allan, A. et al. (1988), "Heat exchange during encapsulation in a

chemical warfare agent protective patient wrap in fouf hot environments." AViation Space and Environmental Medicine, 59, 345-351 .

US Anny Natick Soldier Center (2007) Chemical protective patielll wrap program [CDj. Us AnnyNatick Soldier Center. Natick, MA.

Yokota, M., Bathalon,' G., and Berglund , L. (2008), "Assessmenl of male anthropometric trends and effects on simulated heal Slress responses." European Journal 0/ Applied Physiology, 104,297"302.