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10


EXPERIMENTAL COMPARISON OF TRAUMA IN LATERAL (+Gy),
REARWARD-FACING (+G,), AND FORWARD-FACING (-G,), BODY
ORIENTATIONS WHEN RESTRAINED BY LAP BELT ONLY

I, Introduction.

Consideration of restraint protection of occu-
pants in aircraft or other vehicles has emphasized
the forward- or rearward-facing positions, which
are most commonly utilized. However, in many
instances individuals are normally transported
laterally to the direction of flight, as occurs in
commercial aircraft, either involving aircrew po-
sitions occupied by the flight engineer or stew-
ardesses, or by passengers in lounge seating.
Many military aircraft and especially troop heli-
copters still utilize sideward-facing passenger
and crew positions. On the ground, people travel
“sideward” in buses, on trains, and subways, as
well as in other specialized vehicles. In addition,
lateral loadings in the +Gy, body axis commonly
may occur to individuals in automotive collisions
during side impacts, may occur with capsular
ejection systems in landings, and may be ex-
perienced both in spacecraft and aircraft lateral
oscillations and turbulence. The crash landing
of most commercial aircraft and many general
aviation types in the light-twin category will
expose some occupants to lateral forces, and in
addition any aircraft may skid sideways, thereby
changing the main direction of force to a lateral
one.

The question of the safety of crewmembers and
passengers occupying sideward-facing seats in
commercial aircraft has never been adequately
investigated and, recently, serious concern has
been expressed by representatives of the Steward
and Stewardess Division of Air Line Pilots Asso-
ciation, the Society of Automotive Engineers,
S-9 Cabin Safety Provisions Committee, and
others. This study was initiated because of the
lack of realistic data concerning the tolerance of
the body to lateral impacts and knowledge of
specific injury hazards not common to forward-
or aft-facing impact orientations. It was be-

lieved that insight into the particular problems
or mechanisms of injuries would considerably aid
in design of protective devices as well as assist
in evaluation of present sideward-facing
environments.

Previous evidence suggested that the body is
less able to tolerate lateral impact?? and that
sideward-facing seat tiedowns and restraints may
not provide adequate protection in crashes.**
Injuries to passengers and at least one fatality
to a crewmember have been documented. While
the Air Force specifies 16g. passenger seat
strength requirements to face rearward,’ the
Federal Aviation Regulations (FAR 25.561)
specifies design values for forward-facing seats
to 2.0g. upward, 9.0g. forward, 1.5g. sideward,
and 4.5g. downward, while TSO C-250 (NAS
806 spec. 4.3.1.1) states “when a seat or berth is
to be installed or adjusts to face in other than
the forward direction, sufficient tests shall be
made to substantiate the seat strength for all
intended positions.” *” The interpretation of this
ruling by Flight Standards Division, FAA, is
that it is the manufacturer’s responsibility to
perform the necessary tests to insure that such
seats meet these specifications. A seat designed
for 1.5g. sideward loading will not necessarily
support 9.0g. when turned 90°, so that the side-
ward load becomes the forward component.
Upon inquiry, one manufacturer stated that they
had run static tests to insure that that particular
seat met specifications. Yet Haley, in a 1962
engineering evaluation of military personnel
restraint systems concluded, “only dynamic tests
can reveal the weak points of a restraint sys-
tem...two seats, designed to equal s¢atéc loads,
will not behave the same when subjected to
dynamic (crash) loads.”* Turnbow, e¢ al. have
reported that existing side-facing seats in U.S.
Army aircraft were understrength and not de-
signed to provide adequate restraint, reeommend-



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II. Materials and Methods.

Twenty-four deceleration tests were performed
on 24 adult female Savannah baboons* (Papio
cynocephalus), ranging in body weight from
9.5 kg. to 12.7 kg. (21-28 Ibs.). Age estimations
based on dental examination ranged from 414 to
12 years (CS). Animals were provided by CAMI
through the breeding colony maintained for
cardiovascular and stress research at the Uni-
versity of Oklahoma or from International
Animal Imports, Detroit, and shipped by air-
craft from 1 to 10 days prior to tests at Hollo-
man AFB.

Tests were run between 23 May and 26 August
1966, utilizing the Daisy Decelerator of the 6571st.
Aeromedical Research Laboratory at Holloman
AFB. The seat was an F-111 test frame, modi-
fied for baboons, and mounted on the ARL
Omnidirectional sled. The nylon lap belt of
4,500-lb, strength was replaced for each test and
installed at a 55° angle to the seat pan. Prior
to each run, static belt tension for each side was
stabilized at 1.5 kg. (3.3 Ib.) utilizing an Ohaus
Cenco Model 5610 Scale. This provided the same
degree of belt “tightness” for each subject.

Test conditions involved 0°-5°-0° seat orienta-
tion (seat sideward facing, 85° from horizontal)
for all tests. Protocol was established for two
runs at each level of impact at 15, 20, 25, 30, and
44g. in the lateral position, and one run at each
level from 15-30g. in the forward-facing (—Gx)
180°-5°-0° and rearward-facing (+Gx) orienta-
tion. Time duration was to remain constant, but
varied from 0.076-0.100 second total duration,
the longest time duration at 30g. the Daisy track
was capable of providing safely with this sled
load. Entrance velocities varied from 36.4 ft./
sec, (15g.) to 88.2 ft./sec. (44g.), and rate of
onset from 1,200 to 5,900 g./sec.

Prior to each run the subject was anesthetized
with 1 mg./kg. body weight of Sernalyn.@)
She was then removed from the cage after the
drug had taken effect and prepared for the test
in an adjacent surgical room. Hands and feet
were covered with tape to prevent the chance of

*The animals used for these experiments were law-
fully acquired and treated in accordance with the
Principles of Laboratory Animal Care issued by the
Animal Facilities Standards Committee of the Animal
Care Panel, U.S. Department of Health, Education, and
Welfare, Public Health Service, March 1963,

injury to investigators and the animal was muz-
zled to prevent injury to the tongue during im-
pact. Body measurements were taken with an
anthropometer and sliding caliper. In some
cases, previous longitudinal series of anthro-
pometrics had been taken periodically on animals
originating from the colony at the University of
Oklahoma, and in these cases, only a few meas-
urements were required. The animal was par-
tially shaved down the chest, abdomen, and
thigh, and tincture of Benzoin was smeared over
the skin. Three-quarter-inch photometric “tar-
gets” were then placed in position on 3-inch
Dermicel surgical tape, which formed a contrast-
ing background. Target locations for each ani-
mal were accurately measured. Five general
locations included (1) head (30 mm. posterior
to glabella), (2) centered on the muzzle, (3) on
the upper chest (40 mm. inferior to supraster-
nale), (4) mid-chest (310 mm. superior to
symphysium), and (5) abdominal (150 mm.
superior to symphysium). The purpose of the
“targets” was to provide information on body
kinematics during impact through high-speed
photometric camera coverage and computer
analysis for acceleration, velocity, and distance
relationships with time (Figure 1).

The animal was then taken to the track sled
and the seat belt tension adjusted to 1.5 kg. and
positioned. Low-strength masking tape was
used to keep the legs and thorax in good position
for the run; however, this tore upon impact and
did not provide additional restraint protection.
Muscle tonus was carefully monitored and all
runs were made at the same clinical level.

The strain gauges were fabricated for the
6571st Aeromedical Research Laboratory by
Land-Air Division of Dynalectron at Holloman
AFB. They were originally designed for a 2-
inch-wide belt but were modified to the. 1-inch
webbing used in these tests. Gauges were placed
at each end of the belt, two for lap belts and the
diagonal belt, and four were utilized for each
three-point harness. Each strain-gauge buckle
was instrumented with four strain gauges in
order to measure the bending. moment due to the
force imposed on the belt. When the belt was
stretched, the metal of the buckle was stressed
and deflected. Although each buckle contained
eight elements, it electrically appeared as a four-
active-arm bridge. Resistance across the electri-
cal elements changed as a result of changes of



ing troop seats be designed for dynamic load
factors of 26g. for 0.20 second, and 45g. for 0.10
second for lateral impact.

However, research to support these require-
ments has mainly been theoretical calculations
by engineers, based upon accident investigation.
Earley,’ in 1961, simulated the Electra lounge
seat belt loadings in the sideward-facing position
and found that, “belt tension loads in the side-
facing seat may be three to six times greater
than the belt load on a forward-facing seat under
the same axial deceleration.” His calculations
demonstrated that side-facing seat belt loads may
be far above the normal expected in the forward-
seated position so that this increased loading
should be considered along with seat structure,
tiedown, and body tolerances. In 1964, during
FAA controlled crash tests of a Lockheed 1649
and Douglas DC-6B being conducted at Flight
Safety Foundation (AV-SER) facilities, the
sideward-facing seats collapsed, and no load re-
cordings were obtained, although horizontal ac-
celeration tracings from the aft floor of the
Constellation (station 1175) appear not to have
exceeded about 2g. until 3.7 seconds, at which
they reached 22g. impact with a 20° upslope.

The lateral impact evaluations to date have
revolved about the seat tiedown and restraint
system and not the total environment, including
consideration of human physiological tolerances.
Our knowledge of human responses to lateral
forces has been very restricted. Most previous
studies, furthermore, have been conducted under
conditions of maximum restraint, offering con-
siderably greater protection to the body than
does the lap belt only. Thus, early animal
studies by Stapp, showing no injury in chim-
panzees of 47g. lateral accelerations (0.140 second
duration),* Robinson’s exposures of Rhesus
monkeys to lateral impacts of 75g. at up to
32 ft./sec. velocities, Clarke’s successful lateral
exposure of a bear to 47g. (with rate of onset of
4,180 g./sec.) without injury,t and Lombard,
et al. exposure of guinea pigs to 240g. for 0.033
second at 100,000 g./sec. rate of onset in a fully
contoured, rigid support restraint system were
conducted with the animals supported by maxi-
mum restraint systems. Initial design of the
Apollo command module was restricted to a
maximum acceleration of 10g. with a rate of
onset of not more than 250 g./sec., due to lack of

definitive data on human tolerances to lateral
forces.

A study by Clarke, Weis, Brinkley, and Temple
in 1968* on 82 human runs produced no adverse
subjective responses to lateral impact up to 22g.
(maximum rate of onset of 1,350 g./sec.), and a
subsequent study by Brown, Rothstein, and
Foster, in 1966**? of 11 human tests, using a
38-inch lap belt, double shoulder harness, inverted
“V” pelvic straps, and head restraint, found no
injury from lateral impact forces to 14g. on the
sled. A study by ZaborowskiTM on the Holloman
“bopper” involved 87 tests on 52 male Air Force
subjects at impacts up to 12g. while restrained
with both lap belt and shoulder harness and side
restraint panel. Whitehouse’? in 1966 reported
18 lateral (—G,) impacts conducted on nine
human subjects impacted at 15g., using head and
torso restraint. Other tests in support of the
B-58 capsule, Mercury, Gemini, Apollo, F-111
and other advanced experimental systems have
also employed maximum restraint systems,? not
comparable to that of minimal lap-belt-only
restraint.

In contrast there apparently has been only one
previously published study involving impact tol-
erance while restrained by lap belt only. Zab-
orowski, Rothstein, and Brown in 1965 published
the first medical investigation on humans (re-
strained by lap belt only) in lateral impact and
these had to be discontinued at 9g. (with impact
durations of 0.1 sec.) due “to subject discomfort
with prolonged stiffness and soreness in the neck
musculatus.” ‘’ Fish and Wright" have described
injuries to four soldiers seated in center-facing
seats of an Army Caribou troop transport. Fur-
ther studies currently in progress by SonntagTM®
involve photometric analysis.

The objective of the series of tests reported
here was to go beyond these subjective limits and
attempt to establish physical end-points of non-
reversible trauma while restrained by lap belt
only. The tests were intended to provide more
valid data concerning, (1) what injuries are
typical in a (+:G,) lateral impact, (2) where the
initial injuries occur and at what force levels,
(3) the mechanisms of these injuries, (4) the
body kinematics in lateral impact, and (5) seat
belt differential forces on left and right side
during impact.


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AM 69-13

EXPERIMENTAL COMPARISON OF TRAUMA IN
LATERAL (+Gy), REARWARD-FACING (+Gx), AND
FORWARD-FACING (-Gx;) BODY ORIENTATIONS WHEN
RESTRAINED BY LAP BELT ONLY

Richard G. Snyder, Ph.D,
Clyde C. Snow, Ph.D.
Joseph W. Young, A.M.
G. Townley Price, D.V.M.
Peter Hanson, M.S.

Approved by Released by
~ oe
Slit Bite. mo
J. Rosert Dinix, M.D. P. V. Sede, M.D.
Curer, Crvi, ArromeEpican Fepera Arm Sureron
Institute
July 1969

Department of Transportation

FEDERAL AVIATION ADMINISTRATION
Office of Aviation Medicine



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strain on the metal. Calibrations were done by
placing a known force on the belt and measuring
the electrical output of the bridge.

Run coverage included use of Fastex 2,000
f.p.s. cameras for frontal and side views, two
Field Emmission high-speed roentgenograms
(Figure 2), (the first was triggered at impact
and the second was triggered at about 0.65 second
after initial sled entry into the brake), and a
metric camera on the last 16 runs. In addition
to 35 mm. and 4x5 still photography, three pola-
roid photos were obtained during each run, pre-,
during (Figure 3), and post-impact. These
served as working references to note position to
the cross-check details of notes, All animals
were sacrificed post-run with 650 mg. Nembutal®
after post-run physical examinations. They were
then prepared for shipment in ice by air to CAMI
for necropsy, which was generally accomplished
within 24 hours.

Il. Results and Discussion.

Three series of impact tests were run to com-
pare the effect of body orientation to force. Each
of these tests is summarized in Table I. Peak g.
forces ranged from 15g. to 44g. in the lateral
series, 16.5g. to 81g. in the forward-facing series,
and 22g, to 44g. in the rearward-facing body
orientation. Onset rates varied from about 1,200
g./sec. to about 5,900 g./sec., and time durations
(plateau) from 0.047 to 0.066 second, with total
time durations ranging from 0.076 second to 0.100
second. Sled entrance velocities into the braking
system ranged from 36.4 ft./sec. (15g.) to 88.2
ft./sec. (44g).

In the lateral decelerations, impact was made
in each case on the animal’s left side, thus seat
belt forces were greater on the right (or rear)
belt. Since the majority of the baboon subjects
weighed about 12 kg. (although one [test #3131]
weighed 21 kg.), or one-seventh (to one-third)
that of an adult human male, the forces are pro-
portionately lower. Forces on the right belt
averaged 62 percent higher than those on the
left with a range from 38 to 94 percent. In the
four forward-facing runs, belt loads were, as ex-
pected, relatively close. Although lateral belt
loads for the “rear” belt’ were higher at every
g-level than for the forward-facing belt tensions,
the relative differences were not found to be as
great in this series as had been previously pre-
dicted.®

Forces on the belt in rearward-facing decelera-
tion were of course negligible, since the subject
was being forced against the seat back and not
against the seat itself. Figure 4 shows a com-
parison of belt loads during 31g. impact in each
body orientation. Note that the lateral peak
loads are reached earlier in the deceleration pat-
tern, 0.070-0.080 second after impact, and remain
high with a much longer and more gradual slope
after decay of the acceleration pattern. On the
other hand, the forward-facing belt loads are
initiated earlier but reach a peak somewhat later
than the laterals, falling off much sooner.

Gross and microscopic necropsies were con-
ducted on all animals except #3130, a 20g. lat-
eral impact, within 24 hours post-impact. Test
#3130 survived the impact and was not termi-
nated in order to follow her subsequent progress,
which was uneventful. The significant findings
of trauma are tabulated in Appendix A.

In the rearward-facing body orientation, all
subjects survived the impact but were terminated
in order to ascertain any nonlethal trauma in-
curred. Impacts to 44g. were recorded. Despite
findings of intracranial hemorrhage in three of
the four cases, these injuries were not sufficient
to have affected survival. The rearward-facing
body orientation, offering good support with wid-
est distribution of force over the body surface,
was demonstrated to be by far the most surviv-
able position in this series.

Forward-facing impacts were run from 16.5g.
to 8lg. The most significant findings were
pancreatic hemorrhages in every case. Intra-
cranial hemorrhage was again found in each
case. This could be a result of the extreme
whiplashing of the head as the upper torso jack-
knifes over the seat belt. This may be more
pronounced in this animal than in the human
because of the baboon’s higher center of gravity.
Linear transverse contusions due to the impinge-
ment of the lap belt in both lateral- and forward-
facing impacts were marked (Figure 5).

The lateral body position was demonstrated to
be by far the most injury-producing of these
tests. The combination of lateral flexion of the
thorax, plus torquing, places unusual stress on
the abdominal and back musculature and viscera.
Injuries fell into several categories. Five ani-
mals received ruptured bladders, an injury which
only occurred in the lateral impacts. Contusions,



Freure 1. Baboon positioned in seat on omnidirectional sled prior to impact run. Note photometric locators on
animal and along left portion of seat back.

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are formed only by the centro-acinous cells with
the release and activation of pancreatic enzymes.
However, this must still remain speculation until
proven, or disproven, by clinical study of
survivors.

Iv.

The results of this series of experiments sug-
gest the following conclusions:

Rearward-facing impacts were survivable for
baboon subjects without irreversible injury up
to 44g. at over 5,800 g./sec. onset rate for 0.076
second total duration.

Forward-facing impacts typically produced
hemorrhages of the meninges and dura at each
level of impact tested, from 16.5g. to 31g. Pan-
creatic hemorrhage occurred in each case.

In comparison to either forward-(—Gx) or

Conclusions.

il

rearward-(+Gx) facing decelerations, sideward-
facing impacts (—G,) were found to result in
significantly greater injury at every level of im-
pact studied, from 15g. to 44g.

Lap belt restraint alone does not provide
adequate protection for the side-facing seated
occupant. Significant pancreatic hemorrhage
and necrosis occurred in impacts as low as 16.5g.
This supports a previous study indicating human
lateral subjected tolerance levels were at 9g.,
considerably lower than in either forward- or
rearward-facing body orientations.

An unexpected finding was the widespread
trauma in the lateral impacts associated with
pancreatic hemorrhage. This was determined
to be due to impact rather than post-mortem
autolysis. Further study of the mechanisms of
this injury and apparent effect upon survivability
should be made.



pN

»

cy

2

10.

Pn

. Eartey, J. C.: Unpublished data.

REFERENCES

Braun, W. K., Rornstetn, J. D., and Foster, P.:
Project Apollo Impact Studies. 6571st ARL, Hollo-

man, AFB, New Mexico, 1966,
Cuanpter, R. F.: Unpublished data, 1966,

Cranoter, R. F,: The Daisy Decelerator, ARL TDL,
67-3, 65T1st ARL, Holloman AFB, New Mexico, 1967.

. CLARKE, N. P., Weis, E. B., Jr. BrinKiey, J, W.,

and Tempe, W. E.: Lateral Impact Tolerance
Studies in Support of Apollo, Report I. AMRL
Memo M-29, Wright-Patterson AFB, Ohio, February
1963.

Electra lounge
seat belt loadings in sideward facing position, 1961.
Aircraft Airworthiness; Transport Categories. Fed-
eral Air Regulations CAM 4b; p. 86,

Fisu, J., and Wrrewr, R. H.: The Seat Belt Syn-
drome— Does it Exist? Journal of Trauma 5:
746-750, 1965.

Harry, J. L.: Personnel Restraint Systems Study:
Basle Concepts. U. S. Army TCREC Technical
Report 62-94, p. 45, 1962.

. “Seats” in Handbook of Instructions for Aircraft

Design. USAF AFSCM 80-1, Chapter 1, Sect. 2,
pH. 1-1, 1 January 1966.

LomparD, ©. F., Bronson, 8. D., THrEpe, F. C., CLosr,
P., and Larmi, F. M.: Pathology and Physiology
of Guinea Pigs Under Selected Conditions of Impact
and Support-Restraint. Aerospace Med. 35: 860-866,
1964,

Rosinson, F. R., Hamurn, R. L., and Cozrmann,
R. R.: Electrocardiographic and Roentgenographic
Response of the Heart to Lateral Impact, AMRL
Technical Documentary Report (in preparation).

18

12. Rorustein, J. D., and Braun, W. K.: Feasibility
Study: Lateral Impact with Standard Aircraft Har-
ness Configuration. ARL-TR-66-3. Holloman AFB,
New Mexico, February 1966,

13. Sonntag, R. W.: Personal communication, 1966,

14. Stapp, J. P.: Human and Chimpanzee Tolerance to
Linear Decelerative Force. Paper presented at Con-
ference on Problems of Emergency Escape in High-

Speed Flight, Dayton, Ohio, September 29-30, 1952.

Srapp, J. P., and Tayror, E. R.: Space Cabin Land-
ing Impact Vector Effects on Human Physiology.
Aerospace Med. 35: 1117-1133, 1964.

‘Turnnow, J. W., Rorne, V. E., Bruaarnx, G. M.,
and Rorener, H. F.: Crash Injury Evaluation.
Military Troop Seat Design Criteria. U.S. Army
‘Transportation Research Command, Fort Eustis, Va.
TREC-TR-62-19. November 1962.

15.

16.

17, Wurrenouse, A. C., Brown, W. K., Foster, P., and
Scugrer, H. F.: Quantitative Effects of Abrupt De-
celeration on Pulmonary Diffusion in Man, ARL-TR~

66-12, Holloman AFB, New Mexico, 1966.

18. ZaBorowsKi, A. V.: Lateral Impact Studies: Lap
Belt Shoulder Harness Investigations, Proceedings,
Ninth Stapp Car Crash Conference, pp, 93-127.

Minneapolis, 20-21 October 1965.

19. ZaBorowsk1, A. V., RorustTern, J. D., and Brown,
W. K.: Investigations in Human Tolerance to La-
teral Impact. Presented 36th Annual Meeting,
Aerospace Medical Association, April 26-29, New
York City, 1965. Abstract: Aerospace Med. 36: 168-

169, Unpublished.



!
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Tot
BIOLOGY
UBRARY

AUTHORS: _ Richard G. Snyder, Ph.D.*
Clyde C. Snow, Ph.D.**
Joseph W. Young, A.M.**
G. Townley Price, D.V.M.**
Peter Hanson, M.S.***

PRESENT ADDRESS: *Highway Safety Research Institute

Institute of Science and Technology
University of Michigan
Ann Arbor, Michigan

**Department of Transportation
Federal Aviation Administration
Civil Aeromedical Institute
Oklahoma City, Oklahoma

***6§571st Aeromedical Research Laboratory
Holloman AFB, New Mexico



ACKNOWLEDGMENTS

The authors gratefully acknowledge the assistance of Capt. Richard
Sonntag, USAF (MC) who has given unstinting support in this project; to
Dr. Allan Katzberg, Southwest Foundation for Research and Education, San
Antonio, for consultation in microanatomy; and to Mr. Richard F. Chandler,
Technical Director, Bioeffects Division, 6571st Aeromedical Research Lab-
oratory, Holloman AFB, for his sincere interest and competent engineering
support. The entire Daisy Decelerator staff of the Land-Air Division, Dyna-
lectron Corporation, deserve commendation for their very able and willing
support. Among them we would like to single out Edward Trout, Robert
Johnson, Robert Goodin, William Taylor and Roger Black for special men-
tion. Lastly we would like to credit Miss Carol Schmirler, of Braniff Inter-
national Airways, Dallas, stewardess representative of the Air Line Pilots
Association, whose interest in airline passenger safety led to this investigation.

Qualified requesters may obtain Aviation Medical Reports from Defense Documentation
Center. The general public may purchase from Clearinghouse for Federal Scientific and
Technical Information, U.S. Dept. of Commerce, Springfield, Virginia 22151,


1000 G's PEAK DECELERATION
sy

_ 800
3 |—RIGHT (REAR) LATERAL
> 600
° mJ
3 hf
= 400 ~~|
= LEFT LATERAL
* 200 i'| REAR FACING ~Y

3 A LZ f. ee ee

‘0 .01 .02 .03 04 .05 .06 .07 .08 .09 10 WW 12 «13 14 115

TIME (SECONDS)

Fraure 4, A comparison of belt loads correlated with deceleration time at 31g. (for side-, forward-, and rear-facing
body orientations).

tears or lacerations, and one complete severance
of the uterus also occurred in five cases. In
three instances, cervical fractures occurred with
complete atlanto-occipital separation and transec-
tion of the spinal cord occurring in one 30g.
impact. Such cervical trauma did not occur in
either rearward-facing or forward-facing im-
pacts. The most significant finding, and quite
unexpected, was that of pancreatic hemorrhage
in all lateral cases except two (one survived and
was not terminated, and the other, being shipped
for autopsy by air express, was lost by the air-
line and was not in condition to assess upon
recovery). Figure 6 shows one case of intra-
lobular hemorrhage typical of this series.

To clarify the role of post-mortem pancreatic
degeneration, one baboon was terminated without
being impacted, and treated in the same manner
as those in the impact series. After termination
with Nembutal, the carcass was held at room
temperature for 114 hours and then packed in
ice in a shipping container. A temperature
probe was inserted inferior to the lower lobe of
the liver and recordings kept. Body temperature
of 96.8° F. dropped to 96.2° F. within 114 hours,
to 64.8° F. within 14 hours and to 48° F. within
24 hours. After 24 hours, gross necropsy and
histopathologic examination revealed mild pan-

creatic necrosis without hemorrhagic pancreatitis.
This indicated that part of the necrosis observed
during necropsy was due to post-mortem changes
in the pancreas, but since associated hemorrhagic
findings occurred only in pancreas of impacted
animals, they were considered to be a direct
result of the trauma.

The significance of the inter-acinar and intra-
lobular hemorrhages observed in the pancreas
at necropsy following impact has been carefully
considered. A search of the literature, and
consultation with other pathologists, while reveal-
ing descriptions of pancreatic injury related to
dietary excesses, direct trauma resulting from
blows over the left upper quadrant of the abdo-
men, surgical trauma, and reflux from the in-
testine, has not revealed similar reports of
pancreatic injury related to sudden, violent com-
pression and/or displacement of the viscera such
as we have found in this series of experiments.
We have observed retroperitoneal and intra-
lobular hemorrhage grossly, immediately after
impact, and these findings and inter-acinar hem-
orrhage histologically. It is clear that there have
been intra-abdominal forces sufficient to rupture
the capillary bed. It is not unreasonable to be-
lieve that these same forces could break the more
delicate radicles of the intra-lobular ducts which



Figure 6. Intra-lobular hemorrhage of pancreas of female baboon subject to abrupt deceleration.

12