I@

OASA 1852

THE EFFECTS OF AMBIENT PRESSURE*ON TOLERANCE O" MAMMALSCTO AIR BLAST

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S7A"IL'UiT NO. I

: i3tt1butoL2 uf TAL-i Zcuent IS Valig

Edward G. Damon, Charles S. Gaylord,WilUam Hicks, John T. Yelverton,

Donald R. Richmond, and Clayton S. White

DfCTechnical Progress Report

on 3 . ,Contract No. DA-49-148-XZ-372

CThis work, an aspect of investigations dealing with

* the Biological Effects of Blast from Bombs, wassupported by the Defense Atomic Support Agency of

the Department of Defense.

(Reproduction in whole or in part is permitted for anypurpose of the United States Government.

Lovelace Foundation for Medical Education and ResearchAlbuquerque, New Mexico

August 1966

0E

VASA 1852

THE EFFECTS OF AMBIENT PRESSUREON TOLERANCE OF MiMMALS

S

TO AIR BLAST

Edward G. Damon, Charles S. Gaylord,William Hicks, John T. Yelverton,

Donald R. Richmond, and Clayton S. White

Technical Progress Reporton

Contract No. DA-49-146-XZ-372 S

This work, an aspect of investigations dealing withthe Biological Effects d Blast from Bombs, was

supported by the Del, nse Atomic Support Agency ofthe Department of Defense.

(Reproduction in whole or in part is permitted for anypurpose of the United States Government. )

Lovelace Foundation for Medical Education ajd -e?-,earchAlbuquerque, New Mexico

August 1966

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FOREWORD •

This report presents the results of experiments designed to investi-gate the relationship between animal tolerance to air blast and the ambientpressure existing at time of exposure. The tolerance of rats, guinea pigs,dogs, and goats exposed in shock tubes to reflected pressures with dura-tions of 16 to 35 msec at experimental ambient pressures ranging from5 to 42 psia was explored. The results indicated he effects ef ambientpressure on mammalian response to "sharp "-rising overpressures of"long" duration were quite significant; viz. , lethal overpressure variedby factors of 4 to 5.

The findings may be applied to problems involving the scalitig of bio- *logical blast effects to differences in altitudt - potential blast exposurein pressurized or evacuated locations. They .. e also of significance in.he evacuation of blast-produced casualties by air or other mtthods in-volving ambient pressure changes.

This study is part of a broad program, the aims of which are theaccurate prediction of numan tolerance to air blast and the develop-nentof appropriate procedures for the diagnosis, prognosis, and treatment ofblast injuries.

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ABSTRACT

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Seventy-six dogs. 43 goats, 211 rats, and '55 guinea pigs were ex-posed to reflected shock pressures at ambient pressures ranging fro rn 5to 42 psa in air-driven shock tubes. Animal tolerance, expressed isLD50-one-hour overpressures rose progressivel" as the ambient pres-sure was increased.

By analysis of the results of this study, combined with those fromprevious shock-tube investigations, a general equation for the regrissionof LD50 pressure on ambient pressure for mammals was derived. Fromthis equation and previous estimates of the LDSO pressure for man's tol-erance to overpressures of 400-macc duration at an ambient pressure of12 psia. an equation relating LD 5 0 presbure to ambient pressure wasdeveloped for the 70-kg mammal 4

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ACKNOWLEDGMENTS4r

The authors wish to express their appreciation to the personnel ofthe Department of Comparative Environmental Biology for their abletechnical assistance in conducting the study. *

Appreciation is also expressed to Mr. WilTer R. Kerzee, Dr, E.Royce Fletcher, Mr. Ray W. Albright, and Mr. Edward A. Spelich forconducting the probit and regression analyles.

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TABLE OF CONTENTS

PaieForeword ............ ................... iAbstr;.ct ...... . . .. . . . .............. .. .. iiAcknowledgments ......... ............ .... iiiIntroduction ......... ...................Materials and Methods ....... ...............

General .......... ............. .. .Shock Tubes ............................... Z

12-Inch Diameter Shock Tube ... .......... z24-40-Inch Diameter Shock Tube .. ......... z

Pressure-Time Measuremcents ...... .......... 2Preseure-Time Sequences ........ ............ 5Experimental Animals ......... ........... 5Analysis ot the Data ........ . . . . ......... . 5

Results ....... . . .. . . ................... 9Pathological Findings ....... . . . . ........ . 9Results of the Probit Regression Analyses .... . ...... 9

Discussion ....... .. . . . . ................. 9Effects of Ambient-Pressure Changes

on Animal Tolerance to Air Blast ... .......... 9Estimates for the 70-Kg Mammal ... .......... 17Pressure Ratio ....... ................ 19Practical implications ..... . . . ........... 19

LIST OF TABLES

1. Animals E.posed to Air IlastAt Different Ambient Pressures •..... . .... 3

2. Results of Probit Analysis ...... . ........ 103. Effecte of Ambient Pressure

on Tolerance of Mammals to Air Blast .... ........ Is

LIST OF FIGURES

1. Diarram of Z4-40-Inch Diameter Shock Tube . . . . . . 3 4Z. Typical Pressure-Time Waveform Recorded by Gasag

3 Inches from Eriplate ..... ............ 43. (a-b) Overall Pressure-Time Profiles at Ambient

Pressures of 7 and 12 Psi& ...... ........... 63. (c-d) Overall Pressure-Time Profiles at Ambient

Pressures of 15 and 18 Psia ... . . . . . ....... 74. Probit Mortality Lines for Rats Exposed to Reflected

Pressures of 16-Msec Duration at Various AmbientPressures . . . . . . .. . I

I .

P r ss re . . =.. = . . . .= . . . . . . .. . . . . .

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List of Figures (Continued) Page

5. Probit Mortality Lines "or Guinea Pigs Exposed to ReflectedPressures of 16-MmeL Duration at Variouw AmbientPressures . . . .. . lz

6. Probit Mortality Lines. r Dogs Exposed to Reflected Pressures of 35-Mec Duration it Various AmbientPressures .... . . ................... 13

7. Probit Mortality Lines for Goats Exposed to ReflectedPressures of 35-Msec Duration at Various AmbientPressures ................. 14

8. Efects of Ambient Prtssure on Mammalian Toleranceto "Long"-Duration Overpres3ure. ... ......... 16

9. Predicted Effects of Ambient Pressure on Toleranceof the 70-Kg Mammal to "Long"-Duration Overpressures . is

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TIlE EFFECTS OF AMBIENT PRESSURE ON TOLERANCE

OF MAMMALS TO AIR BLAST

Edward G. Damon, Charles S. Gaylord, Williarm Hicks,John T. Yelverton, Donald R. Richmond, and Clayton S. White

INTRODUCTION

Investigations have established that injuries from exposure to airblast occur more often in air-contairung organs than in other regions ofthe body. lli As the lungs are very delicate air-containing structuresand are more susceptible to blast injury than other vital organs, most ofthe causes of death from primary-blast effects, such as coronary andcerebral air embolism and pulmonary i."lufficiency may be traced di-rectly or indirectly to pulmonary injuries.

A proposed biophysical mechanism of air-blast injury, which hasgained increasing consideration in recent years, is that injury resultsfrom implosion of tissue and fluids into gas -containing organs as aneffect qf violent compression of the body by the positive phase of a blastwave.I. l T This concept suggests a direct relationship between the ex-tent of lung injury and the change in volume which lungs lergo whensubjected to a blast load. Furthermore, the degree of change in lungvolume, in relation to the magnitude of the blast overpre i sure, would beaffected by the ambient pressure existing in the lungs at the tune of blastexposure. 13

Experiments involving exposure of mice to air blasts at different at-mospheric pressures have verified that ambient pressure does affectanimal tolerance to air blast. 14. 15 Therefore, Ptudies were extended toinclude other mammalian species in order to devise methods of definingthe eflects of ambient pressure on human tolerance to air blast.

This report presents the results of experiments in which rats, guin-ea pigs, goats, and dogs were exposed at d.fferent ambient pressures tolong-duration reflected pressures in shock tubes.

MATERIALS AND METHODS

General

The effects of ambient pressure on animal tolerance lo air blaat wereexplored by exposing rat*, guinea pigs, dogs, and go.t& t j waves ataltered ambient pressures in shock tubes. Previous studies have shownthat compression or decompression of animals soon after blast exposuresignificantly affected the lethality. 14 Therefore, in this study, all ani-mals were held at the experimental ambient pressure (Pi) tar one hourfollowing blast exposure before returrung them to the ambient pressurelevel (Po) of the laboratory. Lethality was assessed during this onr-hour-hold period.

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Shock Tubes *12-Inch Diameter Shock Tiibe

The 12-inch diameter shock tube used for exporinq rats and guineapigs has been described in a previous report. 16 For the present study,the endplate of the tube '-& fitted with a transparent window for observ-ation of the animals dur,..g the pcst-ehot, one-hour-hold period. Eachanimal wad exposed to a reflected shock wave in a wire - mesh cage 4mounted inside he shock tube against the endplatn. Procedural detailsfor conducting these exposures have been reported. 14,15

Z4-40-Inch Diameter Shock Tube

The shock-tube arrangement in which dogs and goats were exposedis shown in Figure 1. The tube consisted of a compression chamber 24in. in c:.ameter and 3 ft long, and an expansion chamber 43 ft 10 in. inlength constructed of three sections: (1) a 20-ft length of 24-in. diameterpipe connected to the compression chamber; (2) a transition section 46in. in length wric)" increased the diameter of the tube from 24 to 40. 5 in.;and (3) a test section hav-ng a diameter of 40.5 ir. and a length of Z0 ft.A storage-tank reservoir, connected to the expansion chamber, was usedto hold the desired pre-shot pressure level in the expansion chamber byadding to or reducing pressure as required.

A diaphragm, consisting of sheets of Du Pont Mylar® plastic, sep-arated the comipression and expansion chambers. Each shet of Mylar(0. 01 in. thick) had a bursting pressure of approximately 20 psi in thistube. The compression-chanber pressure, necessary to produce thedesired reflected overpressure dose, was achieved by using an appro-priate number of plastic sheets.

The dogs and goats were mounted against the endplate closing tl-test section, right-side-on to the incident shock with a restraining har-ness constructed of I-in. nylon webbing. Electrocardiograph (ECG) leadswere attached to the animals and passed through a hole in the endplate toa Sanborn Twin-Beam EGG. The ECG output was monitored visually on acathode-ray oscilloscope to determine the time of death of each animal.

Pressure-Time Measurements

Three piezoelectric pressitre transducers v ere used cn each test-two to measure the peak reflected pressures and one to record the pre-shot and post - shot, pressure-time events. Details of precsure-gaugerecording atd calibrating systems have been previously reported. 1 -

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For measuring peak reflected pressures, two pressuire gauges con-'airung sensors of lead metarnobate (Model ST-2, Susquehanna Instru-ments. Bel Air. Md. ) were moutnted flush with the inside wall of the tube3 in. upstream from the enodplate. This arrangement placed the gaugesdirectly above the ba,k of the animal. The mean of the peak reflertedpressures recorded by the two gauges was taken as the overpressure dosefor a given test. A typical pressure-time waveform recorded by one ofthese gauges is shown iti Figure 2.

Pre-shot and post-shot, pressure-time events were recorded with aquartz piezoelectric pressure transducer (Model PZ-14, Kistler Instru-ment Corp.. N. Tonawanda, N. Y.) mounted in te wall of the tube 9 in.

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upstream from the endplate. The signal from this gauge was passed viaa Kistler Amplifier - Calibrator into a cathode - ray oscilloscope. Thesweep on the oscilloscope was set at 5 sec/cm and manually triggered torecord the following:

(1) pressure change from Po to Pi,(2) decompression from the immediate post-shot, static

pressure level (Pb) to Pi, and(3) decompression from Pi to Po. This step was per-

formed after the animal was dead (as determined bythe ECG) or, in the case of survivors, one hourfollowing the shot.

Pre-shot and post-shot pressurization and decompression times werealso measured with a stopwatch.

IPressure-Time Sequences

The sequences of pressure-tir-e events to which the animals wereexposed in each experiment are illustrated in Figures 3 a-d. Presentedin these figures are the mean times and pressures for the tests conductedat experimental ambient pressures of 7, 12, 15, and 18 psia.

Referring to Figure 3d. the mean rise-time (the change in pressurefrom Po to Pi; i.e., ti) was 7 seconds. The time at Pi pre-shot (tz)was443 seconds. With the rival of the shock wave, the pressure rose near-instantaneously to the , eflected shock level (AP). The positive-phaseduration of the initial reflected wave was 36 msec (t 3 ). Following theshot, the pressure became stabilized in the tube at 30 psia, Pb- It wasretained at this level for 17 seconds (t4 ) before it could be returned toPi in 6 seconds (t5). The animals were then retained at this pressure 0le l for oi e hour (t6), after which they were decompressed to P 0 in 7set.onds (t7,

Experimental Animals

The number, type, and body-weight data for animals exposed in thisstudy are given in Table 1. Both sexes were used in all groups.

In order to check for possible effects of the pre-shot and post-shotpressure changes to which the animals were subjected, controls were ex-posed to the most rigorous combinations of increase, hold, ind releaseof pressure (minus the blast) experienced by the test animals. No effectsfrom these pressure changes were detected in the control animals.

Fatalities were autopsied soon after death; survyvors were sacrificedon the day following exposure.

Analysis of the Data

The reflected pressures required to produce 50 -per cent lethality(LD50) for each experiment were determined by probit analysis of theone-hour-lethality data. 19 Statistical analyses indicated no significantdifferei. es in the slopes cf the probit regressions for the various testsat the 95-per cent confidence level. As a result of these analyses, a Octof parallel probit regressions for each species was fitted to the data forall of the experiments. LD50 pressures and their 95-per cent fiduciatswere obtained from these parallel regression,.

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Figure 3 (c-d). Overall Pressure-Time Profiles at AmbientPressures of 15 and 18 Psi&.

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TABLE I

ANIDALI EXPOVED TO AIR BLAST AT DIFFRENT AABIENT PRESSURES

tzlerimen*a Nunber Body Weight. gramsAmbien Presure, of Standard 4

speies I" _ic Animals Mean I. Rage Deviation

201.1Rate 7.0 is (17027) A 12.4 S(spragu Dawley) 188. 4

12.0 40 (14a-35) A 15.4

174.914.7 27 (i57-z30) A 16.8

19Z. 115.0 76 (170.Z1) a M..

195.2 54Z.0 40 . 160-71) a ZZ.4

191.0.. .. 9¢ia 211 (1 57-Z71) =/17, 6 _

515.5Gauia Pigs 5.0 43 (400-695) 6144.4(Eqliek Breed) 489.

7.0 76 (403.892) Al 5.4 do

421.612.0 38 (400-471) 6 ZO. 1

431. 518.5 53 (37-499) * 25.4

433. 440.0 45 (400-500,) A 2.4

Tota 255(37.692) 4127,i. 7 kg

Dogs 7.0 31 (15 24. 7) a 2.7iMogrel) I. S

11.0 I1 (10.1-45) * 4.8

17,113.0 30 (11.4-27.3) a 3'5

17.3ToW 74 (10. Z-17.31 a 3.3

21.7 kg,eatZ 7.0 29 (15.32. 3) 2 5.5li 3 ) 31.2l

15.0 ,4 114, 5-.,4 . 8) 1,,1,24.3

Tetl 43 (14.S-41.8) ] 9, 1

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RESULTS

Pathological Findings

The types of lesions sustained by the animals exposed to air blast atdiff-rent ambient pressures were not different from those generally re-por.ed in the literature on Blast Biology. The major types of injuriesexhibited were lung hemorrhage, arterial air embolism, hemothorax,pneumothorax, hemorrhage of the spleen, kidneys, liver. walls of thegastrointestinal tract, intercostal regions, and sinuses, and rupture ofthe eardrums, sometimes with disruptxc;, of the auditory ossicles.

Results of the Probit and Regression Analyses

Results of the probit analysis are summarized in Tabie 2. Presentedare the probit equation constants, LD5o pressures, and ambient pressuresfor each experiment. The results indicate that for each species the LD50pressures rose with increasing ambient pressure. Parallel dose-responsecurves fitted to the data are presented in Figures 4-7.

All tolerance values obtained to date for the five sneci' s of animalsused in ambient-pressure studies are presented in Table 3. Regressionsof the form, log y = a + b log x (where y = the LD5 0 pressure n nsig, a =the intercept constant, b = the regression coefficient, and x = the experi-mental ambient pressure in paia), were obtained for each spec&es from Sthese data. Because the slopes of these regressions were not significantlydiffe ,ent at the 95-per cent confidence level, a set of regressions havingcommon slopes was fitted to the data. These curves and their equationsare shown in Figure 8.

DISCUSSION

Effects of Ambient-Pressure Chaneson Animal Tolerance to Air Blast

The results of this study, which indicate that five species of mam-mals exhibit uniformily increasing tolerance to air blast with increasing Sambient pressure, are directly applicable to animal response to "sharp"-rising reflected pressures of "iong" duration. The data apply only indi-rectly to situations involving animal exposure to non-ideal waveforms orblast waveforms having positive-phase duration* shorter than 1-2 msecfor mice, 2-3 msec for guinea pigs and rats, and about 15 maec for dogsald goats. 20, 21

Results obtained here were comparable to those reported by Kolderand Wohlzogen involving explosive compression of rats from initial pres-sures of 1-3 atmospheres to final pressures of Z-lZ atmospheres. withrise time to final pressure near i macc, and animals returned to normalatmospheric pressure in approximately 3 seconds after the testil atmos-phere z 14. 7 psia). 1 LD 5 0 values for irntial pressures of 1, 2, and 3atmospheres computed from probit regression equations were 34.5, 69.0,and 100.4 pbig, respectively. These values compare favorably with ratLD50 pressures of 38.8, 68.8, and 36. 3 psig for initial pressures of 1,Z, and 3 atmospheres, respectively, ini the present study.

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LESULTS Or .'OGfl A14ALYSIS

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Pressures of 16-Msec Duration at Various Ambient Pressures.

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Figure 6. Probit Mortality Lines for Dogs Exposed to ReflectedPressures of 35-Mece Duration at Various AmbientPressures.

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Figure 8. Effects of Ambient Pressure on MammalianTolerance to "Long" -Duration Overpressures.

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The animal exposures in these experiments differed from the true pblast situation in the open in that the pressure in the shock tube, aftereach shot, momentarily stabilized (11-17 seconds) at a static level above rthat of the pre-shot ambient pressure before it could be reduced to theexperimental ambient-pressure level. This difference, however, was

4 probably of little biological significance because the LD50 values obtainedin the studies for guinea pigs and dogs at the normal ambient pressure •(lZ psia) were in good agreement with those previously obtained fr-'manimal-blast exposures free of such aberrations; for example. the 34. 6-and 53. 7-psig values for guinea pigs and dogs, respectively, in the pres-en study, as compared with 34. 5 and 52. 9 psig for these species exposedin a shock tube with open vents at IZ psia to overpressures of near 400-

l msec duration. 17, 23 Additional similar comparisons suggest that it wasthe iitial "sharp" rise in pressure and the duration of the positive phase ofthe blast wave that were significant in causing lethal blast injuries, andnot the immediate post-shot pressure events to which these animals weresubjected. Because lethality was assessed during the one-hour, post-shot period in which survivors were held at the experimeital ambient-pressure level before returning them to the normal atmospheric pressurelevel, the mortality data can be considered free of any bias due to thislast pressure change.

The partial pressure of oxygen (P02 ) in the ambient air during thepost -shot, one-hour-I old period was dependent upon the experimentalambient pressure (Pi). Control experiments indicated that animals notsubjected to blast injury tolerated the lowest and highest pressures (with

4 their attendant PO values) for the times involved in the experimentswithout detectable effects. Possible effects of differences in the P0Z on one-hoar survival of blast-injured animals in experiments of this typehave not yet been investigated.

Estimates for the 70-Kg Mammal4 As the curves nresented in Figure 8 have corrunon slopes, their re-

gression coefficient was used in deriving the following general equation Sfor mammals:

log y = a + 0.828 log x

where: y z the LD 5 0 pressure in psiga z the intercept constant for a particular species

4 x a the ambient pressure at exposure in psia JAn equation for the 70-kg marr rmal was then derived from this gen-

eral equation. The estimated LD 5 0 pressure of 52 psi at an ambientpressure of 12 psi&, as previously reported, 0 for the 7 0-kg marmalwas used in order to obtain the intercept constant for the regression. Theresultant curve and its equation, presented in Figure 9, may tentatively

* be used ior estimating human tolerance to "sharp"-rising overpressuresof "long" duration at different ambient pressures. It should be noted thatall data on which the rcression is based were obtained from blast expo-sure of animals against rclecting surfaces.

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Pressure Ratio P

The data in Table 3 indicate that the ratio of the LDS0 reflected pres- 4s.re (AP) to the experimental ambient pressure (Pi) generally decreasedwith increasing ambient presaure. This trend was clearly indicated bythe mouse and rat data, but was less evident from the data for the otherthree species.

The !act that the LDSo-AP/Pi pressure ratio did not tend to remainconstantwith changes in Pi was indicated in 10 of 16 experiments at alteredambient pressures where the LD 5 0 -AP/Pi ratio was outside the 95-per c 'ntconfidence limits of this ratio for the given species at normal ambientpressure (12 psia). As the majority of these data do not indicate that theLD50 pressure ratio is a constant for each species, the curves and re- pgression equations presented in igures 8 and 9 should be used for scalingLD50 pressures to differences i amb nt pressure instead of usi:ng thenormal LD 5 0 -pressure ratio as a factor for biological blast scaling astentatively suggested in an earlier work. 14

Practical Implications

The results of these studies have sig - 2ficant implications in assessinghazards from blast exposures in pressurized or evacuateJ spaces, suchas caisson tunneling and mining operations, cabins of aircraft aloft, spacecapsules, and perhaps underwater for certain co~iditions of exposure. Forexample, ii a given biological response, such as 50-per cent lethality.results from exposures to "long"-duration blast wave* wit! peak pressuresnear 60 psi at a sea-level surface, then where an ambient air pressure of 03 atmospheres exists, peak pressures of slightly more than 150 psi wouldbe required to produce the same effect; e. g. , tnderwater tunneing hAs beencarr ic out above and below the ambient pressures noted here and explosionsin such locations, all other factors being comparable, would be less has-ardous than at sea level.

The meaning of the present study as far as underwater blast is con-cerned is more difficult 'o assess for a number of reasons. Among themare complicating events .has the depth of the water and explosive charge;t., location of the target with respect to the water surface and the bottom:positive reflections from the latter, the magnitude of which - ak.rong otherthirjs - is a function of the nature of the bottom; and negativr reflectionsfrom the surface, which critically influence the, duration of the overpres-sure, the pulse being very short for near-surface locations and progres-sively longer with increasing cepth. Also, there is the fact that the dura-tions of blast overpressures in water are generally much shorter thaii inair. Too, there are no doubt lifferences in the efficiency with which en-ergy is imparted to a biological target by blast waves in air on the onehand and in water on the other. Such factors make it clear that a strairht-forward inc:ease in blast tolerance may or may not occur for exposuresat incre, sing depths underwater. Without question, the matter is complexand is hardly within the scope of the experiments reported and die ,seedhere.

Implicit in the present study, but documented elsewhere 6 , 10, 14, 15 isthe fact that post-exposure pressure changes have important effects on p

19

chances of survival of those injured by blast. As movement and evacuation4 of blast casualties may entail subjecting them to changing ambient pres-

sures, those who treat blast casualties should know and remember thatdecompression is very hazardous to blast patients, particularly if it occurssoon after injury suchas during early air evacuation. In contrast, imme-diate or early compression "s reduced mortality significantly in experi-mental animals and no doubt would be effective in man; viz., blast injuryoccurring in fligh' in aircraft would subsequently be benefitted by flying atthe lowest practical altitude,

Finally, -hough the resuies of the present study clearly indicate am-bient pressure is a physical parameter of major importance in specifyingblast effects, investigations to date have been limited to assessing animalresponse to "sharp"-rising overpressures of "long" duration. Furtherwork will be required to demonstrate that ambient pressure variation is ofaignificance either for non-ideal waveforms or for blast ov-rpressuresenduring for quite short period. of time.

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REFERENCES

#I

1. Hooker, D. R. , "Physiological Effect@ of Air Concussion," Amer. 4J. Phy.iol 67: Z19-274, 19Z4.

Z . Zuckerman, S. , "Experimental Study of Blast Injuries to the Lungs,"Lancet. Z: Z19-238, 1940.

3. Zuckerman, S. , "The Problem of Blast Injuries,"1 Proc. Roy. Soc.Med. , 34. 171-188, 1941.

4. Fisher, R. B. - P. L. Krohn, and S. Zuckerman, "The RelationshipBetween Body Size and the Lethal Effects of Blant, " Report R. C.

* 284, Ministry of Home Security, Oxford, England, 1941.

5. Krohn, P. L. , D. Whitteridge. and S. Zuckerman, "PhysiologicaiEffects of Blast, " Lancet, 1: 252-258, February 28, 1942.

6. Benzinger, T. , "Physiological Effects of Blast in Air and Water,"Chap. XIV-B, German Aviation Medicine, World War 11, Vol. II,pp 22 5-159, U. S. Government Printing Office, Washington. D. C.

n :1950.

. Desagi, H., "Blast Inbries, " Chap. XIV-D, German Aviation Med.icine, Wor!d War ., Vol. 11, pp 1274-1293, U. S. Government Print-ing Ofidce, Washi.kgton, D. C. , 1950.

8. R sle, R.T, "Pathology of Blast Effects " Chap. XIV-C, GermanAviation Medicine. World War U, Vol. 11, pp 1260-1273, U. S. Gov-ein-5ent Printing Office. Washington, D. C. , 1950.

9. Clenedson, C. -J., "An Experimental Study on Air Blast Injuries,"Acta Physiol. Scad. , 18, Supplement 61: r -ZOO 1949.

10. Clemedson, C. -3. , "Blast Injury," Physiol. Rev.. 36: 136-3S4,1956.

11. White, C. S. and D. R. Richmond, Blast Biology. " USAEC Tech-nical Report, TID-5764, Offie of Technical Services, Department of Commerce, Washington, D. C. , Septemr 18. 1959. AlsoChap. 63 in Clinical Cirdiopuonoary Physiology. Ross C. loryand Burgess L. Gordo.(editor s), Grune and btratton. Inc., NewYork. 1960.

1 1Z. Bowen, 1. G. , A. HolDladay, E. R. Fletcher, D. R. Richmond, andC. S. White, "A Fluid -Mechanical Model n-f the- Thoraco-AbxIrminalSystem With Applications to Blast Biology. " Technical ProgressReport No. DASA 1675, Defense Atomnic Support.Agecy. Departmentof Defense, Washington, D. C., June 14. 1965.

13. White, C. S., T. L. Chiffelle, D. R. Pichmond, W. H. Loc jear,* 1. G. Bowen, V. C. Goldicn, H. %. Merideth, D. E. Kilgore. 1. B.

Longwell. J. T. Parker, F. Sherping, and M. E. Cribb, "The Bio-logical Effects of Pressure Phenornc.,a Occurring Inside Protectivo!Shelters Following Nuclcar Detonation," USeC Civil Effects TestGroup Report, WT- 17, Office of Technical Services. Departmentof Commerce, Washington, D. C., October Z8 1957.

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.Co

@ I.. BwenV. . Gldizn, .W.Merdet. D.E ilgoe. . B

0

14. Damon, E. G., D. R. Richmond, and C. S. White, "The Effects ofAmbient Pressure on the Tolerance of Mice to Air Blast, " TechnicalProgress Report No. DASA 1483. Defense Atomic Support Agency,Department of Defense, Washington, D. C., April 1963. Also inAerospace Med., 3?: 341-345, 1966.

15. Damon, E. G. , "The Effects of Ambient Pressure on the BiologicalResponse of Mice to Air Blast," Ph. D. Dissertation, University ofNew Mexico, Albuquerqie, N.M., June 1965.

16. Richmond, D. R., C. S. Gaylord, and E. G. Damon, "DASA-AEC-Lovelace Foundation Blast Simulation Facility," submitted as a Tech-nical Progress Report to Defense Atomic Support Agency, Depart-mrent of Defense, Washington, D.C., August 1966.

17. Richmond, D. R., V. R. Clare, V. C. Goldizen, D. E. Pratt, R. T..3anchez, and C. S. White, "Biological Effects of Overpressure. ILA Shock Tube Utilized to Produce Sharp-Rising Overpressures of 400Milliseconds Duration and Its Employment in Biomedical Experi-ments," Technic4 Progress Report No. DASA 1246, Defense AtomicSupport Agency, Department of Defense, Washington, D. C. , April 7,1961. Also in Aerospace Mcd., 32: q97-1008, 1961.

18. Granath, B. A. and G. A. Coulter, "BRL Shock Tube Pie,,n-ElectricBlast Gages, " BRL Technical Note No. 1478, Ballistic ResearchLaboratories. Aberdeen Proving Ground, Md.. August 1962.

i9. Finney, D. J. , Probit Analysis. A Statistical Treatment of theSigmoid Response Curve (2nd Edition), Cambridge University Press, * *Cambridge, England, 1952.

20. Richmond, D. R. and C. S. White, "A Tentative Estimation of Man'sTolerance to Overpressures from Air Blast, " Technit;al ProgressReport No. DASA 1335, Defense Atomic Support Agency, Departmentof Defense, Washington, D.C. , November 7, 1962.

Z1. Richmond, D. R., V. C. Goldizen, V. R. Clare, and C. S. White,"The Overpressure-Duration Relationship and Lethality in Small An-tnals," Technical Progress Report No. DASA 1325, Defense Atomic

Support Agency, Department of Defense, Washington, D. C. , Septerm-ber 10, 1962.

22. Kolder, H. and F. X. Wohlzogen, "Explosive Kompression im Ber-eich oberhalb I Atmosphire, " PflGgers Arch. , 265: 348-354, 1957.

23. Richmond. D. R., E. G. Damon, I. G. Bowen, E. R. Fletcher, andC. S. White, "Air Blast Studies with Eight Species of Mammals, "submitted as a Technical Progress Report to Defense Atomic SupportAgency, Department of Defense, Washington, D.C. August 1966.

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DISTRIBUTION

ARMY AGENCIES

Chief of Research and Development, Life Sciences Division, Dept. of the Army, ATTN:CRDLS, Washington, D. C. 20310 (1 copy)

Chief of Research and Development, Dept. of the Army, ATTN: CRDNCB, Washington,D.C. 20310 (1 copy)

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Directorate of Transportation, U. S. Army Materiel Cmd., Washington, D.C. 20315(1 copy)

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Commandig General, Medical Research and Development Cmd., Dept. of the Army,ATTN: MEDPS-CS. Main Navy Bldg., Washington, D. C. 20360 (2 copies)

Commanding General, Medical Research and Development Command, Dept. of Army,ATTN: MEDDH-RS, Main Navy Bldg., Washington, D.C. 20360 (2 copies)

U.S. Army CDC Artillery Agency, Fort Sill, Oklahoma 73503 (1 copy)President, Aviation Test Board, U.S. Army Aviation Center, Fort Rucker, Alabama

36362 (1 copy)Assistant Chief of Staff for Force Development, Dept. of the Army, ATTN: Directorate

of CBR and Nuclear Operations, Washington. D. C. 20310 (1 copy)Commandant, U. S. Army C&GS College, ATTN: Archives, Fort ]L,avenworth, Kan$"

66027 (1 copy)Commandant, U. S. Army Air Defense School, ATTN: Command & Staff Dept., Fort BlUs,

Texas 79906 (1 copy)Commanding Officer, U.S. Army CDC Armor Agency, Fort Knox, Kewicky 40120(I copy)

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Commandant, U. S. Army CBR, Weapons S.-hool, Dugway Proving Gromw, Dugay, Utah84022 (1 copy)

Commanding General, Army Medical Service School, Brooke Army Medical Ceser,ATTN: DCCO, Fort .n Houston, Texas 78234 (1 copy)

Commanding General, The Engineer Center, ATTN: Asat Cmcdt Engineer School, FortBelvoir, Virginia 22060 (1 copy)

Commanding General, 9th Hospital Center, ATTN: CO, U. S. Army NMcar MedicineResearch Det.. Europe, APO New York 09180 (1 copy)

Commanding Officer, U.S. Army Chemical Research and Developmni Lab., EdewoodArsenal, Maryland 21040 (1 copy)

Commandant, Walter Reed Army Institute of Research, Walter Reed Army Medical Center,Washington, D. C. 20012 (5 copies)

Commanding General, U. S. Army Natick Laboratories, ATTN: Technical LiAbrary,Natick, Massachusetts 01760 (1 copy)

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DOCUMENT CONTROL DATA - R&D(3.....uI €I..leoealoe tl. m. 6 elli ~ dw 1.t6-4 . .e be . .. d 14e - Os.- 41 -0 c,, .dJ

I ONIGOATNQ A C ?IVIA Y C .VI t. .aA.) m,. 0RE*@ T GO C.4MX I C LAIU,0IC A ViON

UNCLASSI V 1OLOveLfice Foundation for !Idical E'lcation & Rse.r ,-Albuquerqlut, New i-uxtco J7107

3 IRPORT TIVLI

T'he Effects of Ambient Pressurm on Tolerance of Mammals to Air Blast

4 OSCdIPYIE NO'Ci Tm MI -9 (Tn.4 . 9 s0.e" .) pProgroess

b AUTO$&I 'L..I t.m Om-a)

Damon, Edward G. Gaylord. Charles S., Hicks, William, Yelverton. John T.,Richmond, Donald R., and Wbhie, Clayton S.

* PEPORT DAYS '01 " 0 O '58 10 A*I '5.0OP A0W

August 19ti6 37 23

rkA-49-116i-XZ-372I

6 Poo' C'E 1J@S .40 DAS (A1852- 5* e

4l1 AVAIL11*4 ACI* LII TATIOU UOVICISI

Distribulion of this report in Unlimited.

II $u"lin.9 TARv NOT95 Is sptcmEIg MIUTANT ACTIvITv

II aSITUACY

Seventy-hix dogs, 43 goats, 211 rots and 233 guinia pigs were *xpoeod toreflected Viock preasures at ambient presauves rarging from 5 to 42 pit in air-driven shock tubes. Animl tolerance. expres ed as LD5 0 -onie-hour overpressures

roe progressively as the ambient pressure v. Incrsaned,

By analysis of the results of this study, combined with thoee from previous

shock-tube investlgations, a general equation for the regression of LlD)0 pressurqa ambient pressure for mammals was derived, From this equation and previousestimates of the LD O preasasro for man's tolerunce to overpressures of 400-osecduration at an ambient pressure of 12 pale,, an equation relating LD 50 pressureto ambient pressure was developed for the 70-kg aammal.

D1U0

D D ° * " 1 4 7 _ _ _ _ _ _ _ _

Se ~',rt Cl.,sific..lion

.4LINKA LIX .N-C

. 0 i. a a a a 0a a 4m jm 1 -. 1 j I

Shock81io0oiical EffectsAmbient Pressure EffeCt

* OverpressureSLD 5 0 Pressure

INSTRUCTION --

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