illiIi i/ill 111 IIi

AL-TR--192-0176 AD-A265 884

AR°M EVALUATION OF THE RETROGRADES INFLATION ANTI-G SUIT (RIAGS)T0RR Lloyd D. Tripp Jr. "

N SYSTEMS RESEARCH LABORATORIES ,G DAYTON, OHIO 45440 .

Kathy McCloskeyDaniel Repperger

L Stephen E. Popper

A CREW SYSTEMS DIRECTORATEBIODYNAMICS & BIOCOMMUNICATIONS DIVISION

WRIGHT-PATTERSON AFB. OHIO 45433-7008

R Smith L. Johnston

A WRIGHT STATE UNIVERSITY

T DAYTON, OHIO 45435

O I-R DECEMBER 1992 ("N

FINAL REPORT FOR TIHE PERIOD OCTOBER 1989 TO OCTOBER 1992 •=

[Approved for public release; distribution is unlimited. -

AIR FORCE MATERIEL COMMANDWRIG HT-PATTERSON AIR FORCE BASE, OHIO 45433-6573

S if It;. .. .

NO! I CES.

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TECHNICAL REVIEW AND APPROVAL

AL-TR-1992- 0 17 6

The voluntary informed consent of the subjects used in this research was obtained as required by Air ForceRegulation 169-3.

This report has been reviewed by the Office of Public Affairs (PA) and is releasable to the National TechnicalInfonnation Service (NTIS). At NTIS. it will be available to the general public, including foreign nations.

This technical report has been reviewed and is approved for publication.

FOR THE COMMANDER

THOMAS J- MOORE, ChiefBiodynamics and Biocommunications DivisionCrew Systems DirectorateArmstrong Laboratory

REPORT DOCUMENTATION PAGE1 .

I AGENCY USE ONL.Y , 12 REPORT DAT REPORT TYPE AND DATES COVERED

4 TITLE AND SUBTITLE 5 FUNDING NUMBERS

L r 1:: it' ,,

6 AUTHOR(S)

7 PERFORMING ORGANIZATION NAME(S) AND ADORE SS(ES) 8 PERFORMING ORGANIZATIONREPORT NUMBER

9 SPONSORING MONITORING AGENCY NAMEýS) AND AODRESS(ES) 10 SPONSORING MONITORINGAGENCY REPORI NUMBEH

t -:,. 'ý t4. ": )ýý . [

SUPPLEMENTARY NOTES

12a DISTRIBUTION AVAILABILITY STATEMENT 12b DISTRIBUTION CODE S

13 ABSTRAr'

The Retrograde Inflation Anti-G Suit (RIAGS) was originally designed andfabricpted in the early 1940's by Mr. David Clark and Dr. Earl Wood as TheProgressive Arterial Occlusion Anti-g Suit. Testing of this suit on the Mayo

Clinic centrifuge revealed that the suit provided more g protection than thefighter pilot of the era needed (+2.9 gz relaxed). This technology was

revisited in 1987 by the Armstrong Laboratory and culminated in the development

of a new version of the technoiogy using modern methods and materials. The new

suie consisted of a retrograde inflating anti-g suit which inflated

cephaladward, arterial occlusive cuffs for the arms, and capstan sleeves. These

suit combinations were compared to thie standard Air Force issue CSU-13B/P anti-g

suit. Endurance testing of the current suit involved exposing subjects to a

continuous +4.5 to +7 gz Simulated Aerial Combat Maneuver. Results from this

study showed the RIAGS with rapstan sleeves provided the maximum amount of

protection to the subject in terms of endurance (p<0.01 3 ), followed by RIAGS

alone (p<0.058), Standard CSU-13B/P and RIAGS with occlusion cuffs (p=0. 2 8). In Saddition to the protection issue, RIAGS with sleeves also proved to be the most

comfortable of all the g suit combinations evaluated.

14 SUBJECT TERMS 15 NUMBER OF PAGES

1p.16 PRICE CCGD(

17 SECURITY CLASSIFICATION 1S SECURITY CLASSIFICATION 19 SECURITY CLASSIFICATION 20 LIMITATION OF ABSTRACT

OF REPORT Of THIS PAGE OF ABSTRACT

"�A.; AA.' I'i " I [ I I "A:,

SR' Pr ,84.... .. .. ..¼4" ~ ..

Research on this effort was performed under the 1987 Armstrong Laboratory Director's Fundprogram. The Research was conducted through the Engineering Services Contract F, 33615-89-C-0574 by Systems Research Laboratories Inc. The authors wish to thank the 1)snainicEnvironment Simulator Operations CrewA for their technical assistance throughout this studyand a special thanks to Mr. Robert E-sken and SSgt Rudolph Carlv, right of the ElectronicsSupport Group, and Dr. R.E. Van Patten for hi; efforts in developing this program, We wouldalso like to acknowledge Dr. Earl Wood and the David Clark Co. who provided technicalguidance in developing the new version of the Retrograde Inflation Anti-g Suit (RIAGS).

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TABLE OI-FCONTNTF

Introduction 1Anti-G suit Operation 1 0

Methods 4Subjects 4Equipment 4Experimental Design 5G-ProfilesData Collection 7

Results 7Statistical Analysis 7Subjective Data 8

Discussion 9 0Conclusion 10References 11

LIST OF FIGURES

1. Principle of Operation for the Retrograde Inflation Anti-G Suit (RIAGS) 22. RIAGS with Capstan Sleeve (right arm) and Arterial Occlusive Cuff (left arm) 33. Standard CSU 13B/P Anti-G suit 44. Dynamic Environment Simulator 65. Simulated Aerial Combat Maneuver 66. Total Time at SACM 77. Petechial Hemorrhages ot The Feet 9

LIST OF TABLES

1. Test Matrix 52. Number of High G Peaks Endured 8 03. Comfort Rankings 8

v0

LH~I S PA;E, 1 NTENT IO(NAIJY LREFT BLANK

vi

I NTRI)I ( TI( )N

The development of the Retrograde Inflation Anti - Suit (RIACiS) %as accomplished es part ot

a Laboratory Director's Fund program. The main thrust of thi,, program was, to exploit the

engineering technology of the previously developed progressive arterial occlusion suit (PAO.S)designed by Mr. David Clark and Dr. tdrl Wood in 1943. Initial work with this Suit showeda significant increase in g tolerance of + 2.9 gz when compared to other suits of the era. Adescription of the original suit and studies were reported by Wood et al (2.3,4). Although thissuit provided superior protection, the aircraft of the 1440,s did not require the degree of-protection this suit provided. Because the new ,ersion of PAOS did not cmplo, arterialocclusion of the legs. it was renamed the Retrograde Inflation Anti-(I Stilt (RIA(iS) in 1981),to a\ oid an% confusion about the operation of the suit. The original PAOS design " asresurrected because of the g induced loss of consciousness problem in I 'SAt aircraft and thesuit's apparent inprovement in g protection over the standard Sti 113B P anti-g Stuit.

The approach used in the current suit development was to fabricate a modern version of theoriginal design using current state of the art materials and fabrication technologies. Materiasused in the fabrication of the new suit included nlvon which was used in the restraint fabric"which covered the outside of the suit and interdigitating tapes of the capstan sleeves, as well asthe fabric of the sleeves. In addition. nylon was used in the arterial occlusive arnicu',ts. sidefasteners. gy-suit material, and capstan sleeve adjustment lacing. Anti-, suit bladders wAere"comprised of urethane-coated nylon while the armcuffs and capstan bladders wecre constructedof urethane F.im . Self-sealing quick disconnect fittings were used to facilitate reconfigiuratIToof the suit for use with the optional capstan sleeves and arnicuffs. Bladder fabricati( 1•

consisted of ultrasonically sealing the lightweight urethane material which resulted in minimalweight and bulk.

Anti-g Suit Operation

The maximum operating pressure of the various components of the RIAGS was 12 psi for thearterial occlusion cuffs and the g-stIt which was comprised of a series of ten bladders w,%hichinflated from the ankles to the abdomen (Figure 1). Both the capstan sleeve (left of picture)and the occlusion cuff (right of picture) are shown here for demonstration. When evaluated.the subject wore either both sleeves or both cuffs. The capstan sleeves were designed to hold amaximum pressure of 30 psi. The reason for the extremely high pressure for the capstansleeves is the pressure ratio between the capstan pressure tube and the material of the sleevewhich applies pressure to the skin in a 5:1 ratio M1).

Interconnecting g-suit bladders of the RIAGS enabled the resultant pressure in various sectionsto be adjusted via the use of clamps. This allowed the progressive pressure gradients and filltimes to be manually manipulated. This suit still inflated in a retrograde fashion cephaladward(foot to head), but did not apply arterial occlusive pressures to the thighs as did the originalsuit. The RIAGS suit does not utilize pressure socks or other counter pressure devices for thefeet. Arterial occlusive armcuffs were still an optional part of the suit, as were the capstansleeves. The capstan sleeves contained pneumatic capstan tubes integrated lengthwise via

I0

interditgitating tapes. so as to tighten the ,lee, es around the arms Alhen the capstan trhes Acrc

pressurized. This was similar in design to the capstan type partial pressure suits used tor high

altitude protection in the late 1050's.

PRINCIPLE OF OPERATION

0

SLEEVE OiCUFF

G VALVE

0

RIAGS 0

Figure 1. Principle of operation for the retrograde inflation anti-g suit (RIAGS).

0

The pressure applied to the underlying arms by the tightened sleeve fabric is accomplished byinflating the capstan tube. The design approach of the capstan sleeves offers the typicalpneumatic bladder advantages in that it is low profile, lightweight, causes minimal thermalburden, and has a low pressurization volume. One problem is, however, that arm movementis restricted when the tube is fully pressurized.

0

Arterial occl usion atrncu ft' are pneumatic W adders enclosed in ni l on tahri Pilc htt in arcircuni ferential manner around the arms and were placed proximal to thle del toid UhitiC Ic I ticcuffs wcre similar in design to standard bloo-d pressure cufk. The neA xersion ot Ow, ý st r,described in the Statement of Work dated April 108~7 from thle D a\ id Clark ( 'o. 4',)

The follow ins describes thle methods and results troin g-endl.ran11ce 1eslln1_ "hich c.ompared 1heRIAGS alone, RIAGS Aith capstan sleeves, and the RIA(GS \Aith arterial OCCIlnIR aiii.n

2 ) to the standard cutama% C(iS 1313 1 anti- gsuilt Eilture 3).

0

Figure 2. RIAGS with capstan sleeve (right armn) and arterial occlusive cuff (left armi).

3

li1-ure 3. Standard (S 1313 P iinti-p' suni.

MELTHOD S

Stlibcet- participat ing in this study were \Olunteers from the Sustained Acceleration Stress,IIn lour nmales and three females participated, All subjects had heen briefed onl thle

CXpeCrimen~t rind had -,ixcn informed consent prior to their participation in this, Atud Subjectsranged !n agc f roim to 4(0 vear~s

1~qtuipment

Suhiccis wAore standard* issue fl ight suits and hoot,, tor all ,tand~ard CS1 I 3H P g suitexposures. and long underwear, a T-shirt, and flight hoot,, when testing' the RIAGS c:onditolns.'Ihe reason tor this change in personal equipment was that thle RIM( IS was designed to he worn:indernleath a modiftied fli ing coverall. Suhijects, %kerc inst1rumenlted wkith a standard three leadI ,( ( and (don ned a P(I It) p ~arac ute harness (to be used to~r emegnicriy, egress onlv\ prior tolentrint.rlL the centiritIua, -ah. Atte r enterinrg tilie centrifuge, the suhieO\ct, W a eteC !I a tacsi in le

4

of an A CI 'S [I seat ýk I h a 3) (leg ree seat back angfle trid seccured wkI I a tI fiC ~o t I IICTliIeWtqUICk -disconnect restraint harness. It-, 40ci:,ion to the I (, arterial ox\gen ,ituronrli iý 1 aN

measu red non- invasivl \C LS I(-itg NeleI or N -200 pukse oximeter and at specia Hv ii oW0k d1 earclip which attached to the sutlbVCC ect ar at eve le,-l Ai-terial ox vgen satur, io ~' n vasmontooic(A

throLI~hout th, g exposure.

The centri tuge evalualition involed eoni1paringt the RI AGS fit]i ceverage s v ',L1 lonek.- RI's(with arterial OCCIluSion cuffs. RIAOiS wkith capstan sleevecs, and the current Ai! Forceissu"Tatandard cutaway CM - I AlP B anti -J suit (or Standard Sri t ) None oit the RI A( S condltionsIc tided tfoot co~ erage.

F Xperimlental I)sg

V]i2 Ui £ co~ditions "e re randomi117Cd a,7, ross sujects s u the experimental test, n~i iri Si~rtdn Fahle I,

TABI3I 1. I.TFST M,,ATIRIX.

Subject (Conditions, vs Test SUbjeeLB I) A* C

2A C 13 1)31) C B N4C 1B A 1)

7 B3 I) U A8 I) A B3 C

A =Standard CMI -1313. P) Anti-g Stit1B = RIAGiS AloneC = RIAGiS With Cu~ffs1) = RIAGiS With Capstan Sleeves

An M~ar Hi-I ov. anti-g valve was used to provide g suit inflation during all g exposures. "Iheiarterial occlusion cuffs and capstan sleeves were Intlated to a pre set pressure of 5 sias the

p-of]l pssed through +4 u/. and remained inflated to that pressure until the -~ level A~as lessthan + 4 g/. Pressure in the Sleeves and cuffs was controlled Wnang two electric solenoidsalves which were computer activated via the voltage output t .roni an acceleromietcr.

0i Profilles

This experimrent was conduIcted in the Dvniamilc LI~vi ron ment Simulator, a I Q foot radliusSmnulti-axis man-ratedl centrifulge located at Wright-Patterkon AI13. OH (Fiure 4t.Acceleration profi les for this studv incluided at 4 4 LIZ 30) second wkarmiup run tr-01low d hby at

least 1 in ilutc (it rest at hdliw uc tahout 4- 1 .4 gi ) lh'I II ",s I'0losNACd hw It (O g siC, WSCt,

+~ 4.5 to -71 t-i sinimlaitedI aerial combhat mancu~ er (SA( 'N) profille (I wure S, A h ikh ranlcon01tinouIS!N Lnutl OI the sb eCO reachedl a peripheral light loss endpoint (dei- ned it, it i vijil ci

ts~han 60) degrees), or tatinue.

~ g r

I iLure 4. I Mnamifc Ln\ ronmincu SMILm lator,

SIMULATED AERIAL COMBAT MANEUVERSACM

Gz

t. secs

Figure 5. Simulated aerial combat maneuver.

D.ata Collection

Physiological and "-Suit data were transmitted from the cab of' the cerntritfuge to thC %aimi U

data collection devices v ia slip rings (rotating plate,, and a stationary plate c:onnected A ith

brushes). Remote video cameras provided a front and ,ide % ie'A of* the ,object throughout theexperiment V'ideo imlages of the subj~ects were recorded on 0, 5 inch V14S tape uINITne aPanasonic video cassette recorder. Sub~jects wXere in constantl commu~knication 'A toh III\estigators,

and the physician using a miicrophone attached to the restraint harnes-, and at speaker mountedto the rcý.r of the suhject's seat. Oxvgen saturation valLsitt pressure, cuff' and Jleec epressure, heart rate. and] g-level were digitiied, recordee': oud stored on maigneti tape using aSF1. computer. tData were also recorded in real nime onl a (yould 40(X) brush recorder,Finally. SLubeC~ts were asked to rank the four suits in termis of -comf -ort during acceleration-

R I--S I I.TS

Statistical Analysis

The total time at L, for the S:\C N for the three RIAGiS conditions \,ere comlparecl to thestandard Cu~ta'av. Cm(St 13 B P1 using, the standard t-test 'A hich re\vealed that muh~ects, " earingthe RIAGS 'Aith sleeves, had signi ticantks ;, ger SAU(NI enilurance times, than the standard ,Lilt(p<0,)0 13 See FIigre 0).

RESULTSACCELERATION ENDURANCE MEANS.

RIAGS vs STANDARD ANTI-G SUITN 7

0

z

PIA

G PROTECTION ENSEMBLE

Figure 6. Total Time at SACM.

7

RIA(GS alone neared si,_nItficance (pq <0058). The RIA(GS wil h cults .,as no, stat •is+allIsignificant when compared to tic standard g suit (p =:0. 28) The total t mc at g , as act ua I Ishorter for the RIAGS wýith cut+fs condition vA hen compared to an 0 o' the other suit condit uons1,Fhe total number of high g peaks endured b, each sublect are shown in Table 2.

TABLE 2. NUMBER O1 HIGH gPiFAKS .ENI)DURED

Subject: RIA(iS Standard RIAIS RIAGiSC Cuffs Suit Alone \, Slcec.es

A I1) 1(0 10 17

B 15 10 17 141I 14 22

1 4 14 1 1It iI 14 1sI1 3 4 X 4

a\,g. peaks 7.() 8.1 11 0 14.,

X = missing data

Suhjectisec Data:

Suhiect,, ranked the overall comfort of each suit. Table 3 shows the comfort ranking of eachcondition, as vell a& ',c mean acceleration time of the seven subjects for each of the suit

conditwins Subtccts rated RIA(iS with sleeves as being the most comfortable followed hbRIA( ;S alonc, the ('CS.I-13 BP. and RIAGS with cuffs. Subjects reported their dissatisfaction"with the arterial occlusion cuffs during the post acceleration debriefing. These complaintsw~ere mainly related to the following: tingling of the hands and fingers, decreased dexterity ofthe ringers,. and in some cases fiank pain. All of these symptoms could be attributed to arterialocclusion over long durations (up to four minutes). Pahysiological measures (heart rate,arterial oxygen saturation, suit pressure, and g levels are reported elswhere (6).

TABL3.E 3. COMFORT RANKIN(I (NN=7)

Most Mean TimeSUIT Condition Com fortable Performing. S ACNI

RIA(iS with Sleeves 1 657 secRIAGS Alone 467 secStandard suit 3 322 secRIA(iS with Cuftfs 4 284 sec

8

0

1)tS(1 ISSI()N

Re-evaluation of the RIA(GS technology in terms of endurance rather than a g toleranceenhancement modalit, produced some very interesting results. The use of capstan sleeves Inaddition to the full coverage RIA(IS provided the greatest anmount ot protection and enabledsubjects, on average, to increase their g endurance by 5.5 minutes compared to the standardCSU-13B1 'P and b- 3 minuteS compared to the RIAGS alone. A possible explanation for thisincreased endurance is ,hat the capstan sleeves prevented blood from pooling into the arms.while the RIAGS minimized pooling in the legs. Pooling was observed in the feet of somesubjects since booties or pressure socks were not evaluated \,kith RIAGS. Several sublects •reported severe petechial hemorrhages of their feet after long g exposures usiMg the RIAISsuit (Figure 7.).

PS

0

]0

Figure 7. Petechial hemorrhage of the feet.

It is speculated that the combination of the RIAiS plus sleeves maintained blood return to theheart, cardiac output, and eye level blood pressure for longer periods of time. From ahistorical perspective, full coverage anti-g suits have routinely provided better g protectionthan cutaway versions used over the years (6.7.8.9). The average increased endurance acrosssubjects who used the RIAGS alone, was 2.4 minutes greater than the standard anti-g suit.

9

Thi ws not the cale for the. 1,, aoil cufs. Vi)k i thec short durt ion t, en'riim meonncIused b,, Wood and others (Q), Mi hch showked that -arterial occ1 uslonl en fs'ý had anl addit s e etf teeof' 4 0.0 o/ increase nl tolerance, the c~urrent g enduranice stud,, shox~s hait sN hcn arierialocclusion cti ffs remlain inflated for a long du]ration at a moderate g level, a decrement nl g 0endurance may occnur. Th is wkas demon strated b s the ltime spent at g \x~ rh the arterial occ luiioncuff's ('9 4 sci -,kith cuffs compared to 32' sec Using the standard suit alonet)

Arn mpin experienced hs test subjeCtS t~ea il te occIlusion culffs wýaSpoib th rsul oan

ischenuc: respons~e to has, uis thle brachial arters. occ.luded on anl as erage of' about 5 minutmes Ind aratin Am. hone1 h the coimpl icat ions associated with ischem ia are not cond uc se to the fliv ii

ens i, jr~ow- cut bec.a iise oif SN 11plonis (like tingling of' fingers hand. loss oft function, and fran kTpain. it i,,mporiant to remembner that thie expeirimental constraints placed on this studsdic:tated thj t K .ie rtcri,0l occl usa n en fts výwond remain Intl ated abov c - 4 e/ and that dulring theCS, ' (Nt 1!e cu*ts remained intlated for the duration of- the run. It is conceiisable. hos es er. thatnet iise tit arterial occlusion c~uffs ilav prose eff -ective when used in thle týIpe Of g eXposuires

c~ma xperieniced by tod aý 's Fighter pilot (usuall s less than 5 sec seconds at peakg Thisis atopic I br further research, In addition, it' the pressure in the Cuff's 'Aas mo1dullated sullch as

iin tile anti-,, sur ) , thle cuffs may be more acceptable.

J he RIAGS 'Aas never evaluated for its apparent uitility of cephaladssard \s caudalwardif~oot s ard] ) inftlation-. however, a new Ilull coverage anti-g Suitl has been (1eveloped atArmstrong, Laboratory. Brooks AFB, TX, called ATAGS or Advanced Techniology Anti-6Suit. This Suitl t-ills in much the samne manner as the CSlt-] 131"i but cosers nearly- all oft theio'ker body. includin-v the teet ( 10). The ATAGS is currently being flight tested in highperformlan:ce aircraft and is being, developed because of' its simple. but eftectlis. design. The

ITA IS i demonstrating performance comparable to the RIA(;S.

(?ONCLI [SION

RIA(iS ssith sleeves provided the greatest degree of protection compared to both die -standardanlti-2 suit andl the other RIAGiS conditions. The RIAGS full coverage anti-g still did exhibitgreater protection than the standard anti-g stilt. The use of arterial occIlusive arm cuff's in thelong duration v environment Proved to be prohibitive because of pain subjects experienced intheir hands. Perhaps a reduIced pressure scheduile in these cuffs would lead to greater subiectacceptance. The RIAGS is not irecomnmended for further development as a g protectionsystem:ý a nei,&. low-er torsolull coverage anti-g protection system called the AdvancedTechnologi, Anti-6 Suit (ATAGiS) is being developed for replacement of the standard anti-gsuilt in high performance aircraft. 41

to6

0

RI F 'RI EN C I S

0

1. Howard, P. The Physiology of Positive Acceleration, In: JA. Gillies, 'd.. A TextbookOf Aviation Physiology. (Chapter 23), Pergaman Press, New York: (1965).

2. Wood, E.H. Acceleration Requirements Then and Now. First lnterservice!lndustryAcceleration Colloquium, May 19, 1987. Wright-Patterson AFB. Ohio. Videotapeavailable upon request to AILCFBS Wright-Patterson AI:B, OH 45433 (send blanktape).

3. Wood. E.H. Contributions of Aeromedical Research to [light and Biomedical Science.Aviat. Space Environ. Med. 57, (10), (Sup), A 13-23, (1986).

4. Wood, E.H., l~ambert. t.H. Blades. EJ.. Code, C.F. Effects of Acceleration inRelation to Aviation. Federal Proceedings 5. 323-344, (1946).

5, Clark D. Statement of Work. Progressive Arterial Occlusion Anti-G Suit April 1987.AL'CFBS Wright-Patterson At-B OH.

6. Johnston. S.L.. Tripp, I.D.. Repperger, D.W. An lnvestipatlon of Middle CerebralArtery Bloodflow, Velocity and Arterial Oxygen Saturation Under Sustained PositiveGz, presented at the Aerospace Medical Association Meeting. Miami FI,. 10-14 May'1992.

7. Krutz, R.W., Barton, R.R. The Effect of Uniform Lower Body Pressurization on +Gz"Tolerance. Aviat. Space Environ. Med. Aerospace Medicine Preprint, 62-63, (1974).

8. Burton. R.R., Krutz, R.W. G Tolerance and Protection with Anti-G Suit Concepts.Aviat. Space Environ. Med. 46, (2). 119-124. (1975).

9. Wood, E.H., Lambert, E.H. Some Factors Which Influence the Protection Afforded byPneumatic Anti-G Suits. Aerospace Med. 23, 218-228, (1952).

10. Meeker, L.JT Effects on Gz Endurance/Tolerance of Reduced Pressure Schedules Usingthe Advanced Technology Anti-G Suit (ATAGS), AGARD-CP-516, October 1991.

Priongofice 19:1 7,4* 60,0