EKG
were also iuplanted into the sealp and elbow of
the fetus (Fig. +). ‘ing the pla-
venta with implanted leads. the placenta had

pressure transducer introduced. leads

To avoid pie

been localized previously by means of ‘Pechni-
tium 99 seanning, Lost amniotic tuid was re-
placed, and the werine and abdominal incisions
closed,

The receleration pattern in ‘Test 1 was 40 g.
at 4.000 gosee, rate of onset and a plateau diara-
fion of O.U80 sec, at ST fl sec. entrance velocity,

This pattern was derived from a program de-

Hlerative forces: sus

ed to compute the de

tained by a typical passenger in a hypothetical
four engine jet airliner crashing on takeott.
will be seen, this pattern proved to be nonsur-
vivable, and in ‘Tests 2 changed
rate of onset and a phiteau

7. the pattern wa

see

Fiarne,

HII. Results.

Test 1 (Daisy Run
honpreguant ferme,

PASO) —-The subject was a

This animal was a control
used to evaluate equipment: and procedures and
to determine the f
The animal was anaesthetized

asibility of the impact profile.
with Sernalyn

Ling. ky. body weight. No physiologiea! vari-

ables were recorded. Impact entrance velocity was

ST ft. see with a dO gy peak at 4.000 psec. rate
of onset. and a plateau duration of 0.80 sec.

The animal was killed by the impact. High-

ted severe whiplash

speed photography demonst
kinematies. Autopsy revealed a complete transec-
tion of the cord and total subluxation of the
athuito-occipital joint, “The vertebral arteries
were ruptured bilaterally sith massive hemor
rhage into the soft tissue of the neck and superior

mediastinum. Both ila were transversely frac-

Fully instrumented and anaesthetized pregnant baboon seated in restraint chair prior to impact.


vegn cy

GF ~

we

Fier: 7 Fetus with placenta attached. (Although ne clinic evidence of trauma wats observed, impact was fatal

Te ferns)

0.000 0030 ° = 0.090 0.140 0.220
TIME (SECONDS)

8. Comparison of lap belt with lap belt plus shoulder restraint

8


there appeared to be no il effects from the first
Impact. The deceleration pattern was identical.
2 excellent comparison of the effects
with the effects of seat) belt
Avtitic pressure
The

Hg. over baseline. dropping to 130 mun.

providing 4
of seat belt
shoulder harness,

and

uterus

showed a double peak. inst ovcurred at
400 mim.

Ig. below baseline and peaking again at (70 min,

Ig. The first peak ocenrred ar O.0d0) see. and
the second ar WE see after the onset of de-
celeration, — Post-inpact bradyeardia was ob-

served in this animal. Autopsy revealed imines

natin consisting of a hematoma in the right
nuinal canal and rupture of the faleiforny lig
ment of the liver (Pig. 6).
Test > (Daisy Run 28x8)
160-day
GU8 ft ese, entrance velocity, 2.000 see

1

The subject: was a

pregnant baboon, impacted at vo e..

ate of
plateau duration of U.S sec,

onset, with a

Transient post-run bradyeardia was observed in
both the mother and fers As the sled was
accelerated. the intrauterine pressure rose to

60 mm. Hy over baseline. Tt peaked at 240 mim

Hg. over baseline at 0.055 see. after the onset of

o"
oe
i

goa

Figure 4.

deceleration. It then dropped to Tf mim, Tig.
IIeo at

Autopsy of the mother revealed sub-

and rose to a second peak of 20 mn
ULE see,
chorionic hemorrhage, subserosil petechiae in the
wall of the jejunum. :
No

nd separation of the right

sitevroiliae joint tram to the fetus was

observed (Fig. 7).

Test 6 (Daisy Run 301) The subject was at

pregnant baboon with a gestation time of ap-
Ho days.

20g. 2.000 g. secs onset rate. with a plateau duari

proximately She was impacted at

tion of (@0s0-sec. Tn this animal. the intrauterine
pressure rose 10 60 tn Lig. during the early
phase of acceleration, but dropped back to base-
Tine (lo nun, Hyg.) inmnediately prior to impact,
Following the onset of deceleration. if rose to
6o tum. Tg. above baseline ar (iii see. ‘This was
followed hy a strong negative pressure of 380
tnt, Hy. 090 see after onset of sled decclera
Him, He.
HL sev \

brady

tion, and a sevond positive peak of

ACO LES see. retining to baseline at ¢
fetal

truisient: maternal and nurdli wa

rin noted.

Surgical implantation of EKG leads in sealp and elbow of fetus.


tured, a finding considered artifactitious inas-
much as the essentially quadrupedal-type pelvis
of the baboon coupled with its poor gluteal
development make it particularly liable to such
fractures when a lap restraint: is used without
The

ws of this auimnal was sheared frou: its major

compensatory subischial seat padding.

we
anterior pelvic support

Because of the extensive triuma. it wits decided
that the deceleration profile was too severe. Seat
padding and a headrest were added to the seat.
Vet for Sernalyn in
subsequent tests beewuse the litter drug appeared

Innoy was substituted

to depress muscle tonus for an inordinate length
of time.

Test 2 (Daisy Run vssz) ‘This test was run

with i nonpregnant female baboon with a

surgically implanted artificial uterus, The sub-
ject was anaesthetized with a Lo ec. Innovar Vet
Lninistered hours before
the run.

entrance velovity at

approximately i

The test profile was we. GL ft see,

HOW gaosec. rate of onset,

with a plateau chiration of (080 see. In orde

to determine the intranteriue pressure changes

0h lcrxXa

to be expected in the gravid uterus. pressure
changes in the simulated uterus were monitored,
Fr lo
“ntrauleriie” pressure rose to 380 tim, THe
the
no further data were recorded. Ag

Ig. the

mon The.

om a baseline pressure of
al

which time leads became disconnected and

run. bilateral

fracture of the tha occurred beeause of insuf-

ficient seat padding. For sibsequent tests. more

seat paddling: was added,

Tes 3 (Daisy Run ssai Phe subject was a

nonpregnant female baboon with an artificial

Tnnovar-Vet anesthetic injected

The deceleration protile

neers. wus

ft hours prior to impact.

was ZO gt GU TL sec, entrance velocity. at
2.00 @, see. eof onset. with a plateau duration
of W080 sec, The temporary shoulder restraint

did not rel the animal

was impacted with an effective shoulder harness

tse prior to impact: thy

as wellas dap belt restraint. Baseline intrauterine

pressure measured 125 150 au, Ha. with a single

peak of approximuuely S00 ain. Tle. occurring
apposimately 0.059 sec. after impact (Fig. 5).
Tet 4 (1

same animal as in ‘Pest 3. utilized again after

v Run 2886)—The subject was the

Fiavrr 3,

Attachment of seat belts at rear of seat and initial adjustment a

4


rose approximately 15 mm. Hg. above baseline
during At 0.050 sec, after the onset
of deceleration, it peaked at LS mm. Tg. follow-
ing which a drop of 460 mm, Hg. below baseline
oceurred at 0.135 sec. A second positive peak
HO mm. Ig. ar O.1s5 see. Transient
mother and fetal bradycardia were again ob-
served.

As in the previous test, no dis
trauma to the mother was obse:

‘eleration,

was of

cernible external
ved buteat 1s hr.
post-impact fetal heart rate could no Tonger be
recorded or heard. and caesarian section produced
Kechymotice areas were ir-
regularly distributed on the head and upper
torso of the fetus.
pending, ‘The mother was found in moribund
shock in her cage the following morning, and
died in shock approximately 20 hours after im-

a. stillborn baby

Further autopsy results are

S

nalyn anaesthesia. she was subjected to the
sume instrumentation and restraint procedures
used in the previous tests without. however, bein;
impacted. During this procedure, the amniotic
sae was inadvertently ruptured.
sure. the animal was returned to her cage.

Following clo-
No
change in fetal heart rate or maternal blood
pressure was noted during the procedure, The
next morning, however. the fetus was found dead
in the cage. the animal to
The cause of intrauterine

Autopsy revealed
have been stillborn,
death was a subdural hemorrhage which is ap-
parently a birth injury. It is planned to repeat
this coutrol procedure at a later cate,

Seat Beli Forces- -Forees on the v
sides of the >

ht and left
U for all ime
4.5. Gand 7.
symmetrical and

belt were ta
est 1. In
were essentially

SUP

‘est

paets except

the results

pact. Autopsy results are not yet available. ranged from 450-610 Tbs. with a mean of 516 Ths.
Test § (Sham Run)-~The subject of this ex- The peak in belt forces occurred betweet U.105-
periment was a 14-day pregnant baboon, After 0.135 see. after the onset of deceleration, In
SLED ACCELEROMETER
20¢ | TM | 4
ot
Oo 10F 5) N
$ baa
| Mm
°
600 RIGHT SEAT BELT TENSION
g i |
S 300F >
é cy
°
600 LEFT SEAT BELT TENSION
o
aol L——T
5 300F ea rN | |
é | J
()
600 UTERINE PRESSURE
i Va LT-N
400F) | Y MN
2 IN iY NI
= 200f [A N N
€ t | ‘a
Eo
DAISY RUN * 2886
-200b PREGNANT BABOON

>| | 0.0! Sec

6

Results of iinpaet test No, Awd (Daisy Run No, 2

7

ENT. VEL. 60.3 ft/sec.



AM 68-24

IMPACT INJURY TO THE PREGNANT FEMALE AND
FETUS IN LAP BELT RESTRAINT

Richard G. Snyder, Ph.D.
Clyde C. Snow, Ph.D.
Warren M. Crosby, M.D.
Capt. Peter Hanson
Maj. Jerry Fineg
Richard Chandler

Approved by Reteased b:

Pilot Pte Sizgel wt

J. Roverr Dine. M.D.
Corr, Cro, Arkeaepioan ENsrire:

December 196

Depariment of Tri Tekan
FEDERAL AVEATION Ai or SES TRA EOS
Office of Aviation Medic: ix


apparent to the fetuses at autopsy. The most
likely cause of death would be maternal neuro-
genic shock, Our attempts to monitor maternal
blood pressures were fraught with technical
difficulties, but ausculatory methods were utilized
-impact on one oecasi: est 7) and hypo-
ve values were found. Studies are now in
progress to remedy the instrumentation problem.

It is to be pointed out that placental separa-
tion, an expected finding, was not produced in
any of the three pregnant animals impacted.

The finding of maternal post-impact brady-
cardia confirms earlier observations of this phe-
nomenon by other workers Tts oceurrence in
the fetus, however, is an observation of extreme
interest and one which may aid in determining
the mechanism by which such bradycardia is
produced.

Future runs will be concerned with answering
the following questions:

sion ('

1. Does maternal shov
deceleration? If so, what hypotensive levels are

occur following abrupt

attained, and is this related to the death of the
fetus?

At what level of derelerative force does
placental separation occur?
Atowhat level of develerative force does

uterine miplire ocour %

4. Can changes it the re
position alter the survival rate of the fetus?

raint system or seat

Vv. Summary.
iminary data have been accumulated from

of deceleration
Iaboons. “Three of these animals were pregnant.

seven xperiments on

and, in two fetal death oceurved 1-2 hrs.
after impact.

sae

(The third fetus and mother were
ificed tumediately ater impact.)

The cause
It
should be emphasized that the seat belt affords
{ion to any pregnant oceupant
over non-use of a belt, and the anthors do not
wish to imply Chat the belts per se are dangerous.

of fetal demise has not yet been determined.

considerable prot.

REFERENCES

. GAUDAEN, G

Letter to Dr, James 1. Goddard,
Department of Mealth, Education and Welfare. ex-
pressing opinion of SAK Motor Vehicle Seat Belt
Committee ax to question, “Should seat belts be rec-
ommended for pregnant women? 1955

2 Gen Joo AL and: Tremser,
Travel on Enterruption of Preg

: The elfect of
An Auslysix
300. Miles.

Vol. 66, p. 12241
Commercial Aviation; Med-
Muroc Med. Vol

nic

3. Laverne, Supe
ico Physiological Perspective,
2, pp. 799-804.

senger Flying.”
381, May 1961,

Acrospace

10

5. Renovits, PF aumatic Rupuwe of the Pregnant
Uterus trom ‘Seat Bell! Iujury, Am. J. Obs, and
Gyn., Vol. 90, pp. 828-829, 194,

J. Po and Tayior, BE. 2: Space Cabin Landing

Vector Effects of Human Phys‘ology.

» VoL 85, No, 12, pp, 1117-1133, 1964.

nd Ramis, L. We: Physiological Ef
fects of Abrupt Develeration: 1, Relative Bradyeardia

Paper, 33rd Anum Meeting of Aerospace Medical
Association, April 1962,

» Wens, C Be: Travel Duving
Gun. Vol. 4. pp. :

| Warerixenan, H
Women. Pract, Vol

lero

Obs, and

5.

muey,

of Pregnant
1,

‘Transport
16, pp, 156 158, 1



sults from Test 3, in

strong contrast are the
which the shoulder restraint failed to release.
In this test. forces were recorded at 0 ths. for
both right and left helts (Pig. 8).

IV. Discussion.

From these preliminary data, it apparent
that the sequence of events following impact of
the pregnant baboon in the 0 45-0 position is as
follow

animal
intrauterine

1. During acceleration, the awake
tenses the abdomen,

pressure prior to impact.

raising the
2. At approximately 0.050 sec. after the onset
of deceleration, the animal is pressed into the
seat, causing a rise in intrauterine pressure befor

SjackknifingTM begins.

3, Following the initial positive peak, the
intrauterine pressure drops sharply at about
0,100 see, and then rebounds to a second, positive
peak averaging about 400 mm, Hy. at about 0.170
see, This second peak is attributed to the sudden
impingement of the uterus between the belt and

the spine when the animal is fully flexed an-
teriorly (Fig. 9).

This analysis is supported by the absence of
the second peak in intrauterine pressure observed
in Test 3 in which the shoulder harness failed
to release. It is interesting to note, however.
that in this animal the maximum uterine pres-
S00 mim. Hye. or very similar to those

restrained by lap belt alone despite the
fact that forces on the seat belt were much lower.
This finding indicates that, insofar as the gravid
uterus is concerned. in impact with any appreci-

able forces along the vertical body axis (as in
increases in intra-
uterine pressures can be expected, even when the
body is totally restrained from forward flexion.
Whether such an increase ix as deleterious to the
fetus as experienced when the uterus is impinged
between belt and spine can only be determined

the (15-0 position) stror

through further studies comparing seat-belt-only

With seat-belt-plus-shoulder-haress impacts.
Fetal demise occurring 1-2 irs. after impact is

difficult to explain. There were no gross injuries

INTRAUTERINE PRESSURE IMPACT SEQUENCE

A 8
308
‘ SLED
ACCELEROMETER
rr ns
4

BASELINE 10 mm Hg

c tt)

440:

SEAT BELT
TENSION

UTERINE

380mm HR PRESSURE
0.000 0.050 0.100 0.140
TIME |SECONDS|
PRE-IMPACT PRIOR TO INITIAL FULLY
ACCELERATION JACK-KNIFING JACK-KNIFE FLEXED
* TENSES ABDOMEN © PRESSED INTO © INTRAUTERINE © INTRAUTERINE
RAISES INTRAUTERINE SEAT PRESSURE PRESSURE REBOUNDS:

P
RESSURE © RISE IN INTRAUTERINE

PRESSURE BEFORE
JACK KNIFING BEGINS

Figure 9,

OROPS SHARPLY TO SECOND PEAK
AVG 400 mm He
AS UTERUS IS IMPINGED

BETWEEN BELT AND SPINE

Intrauterine pressure impact sequence.

9


Tarte 1—Mean Maternal and Fetal Heart Rates far
Pregnant Animals Subjected to Tnpaet

Time Maternal ep Petal ve min
Pre-run 1 150
Post-Impact aT

Linutes $ nt
Minutes Wie rw
» Minutes Wie. 140

Although there was no immediate clinical evi
fetal heart-
beat could no Jonger be elicited approximately

dence of injury to mother or fetus. fe

ily he. post-run. and the
Atops:

a section.

y of the fetus rev
no gross or microscopic signs of Cau.

baby was stillborn at

mother recovered without complications.

Lidalay pregnant baboor

2,000 se

Nembutal
of

hours prior to impact.

of 0.0950) sec,

ata dosage ao

nie

SLED ACCELEROMETER

20

"G6"

Zest 7 (Daisy Run 362)

The subject was a

1 impacted at 200g

rte of onset. with a plateau duration

anaesthesia was given
approximately 4

Tatranterine pressure

U/

SION

Ll!
l

RIGHT SEAT BELT

» 600
me)
s sf
[o}
a

)
, 600 LEFT SEAT BELT
mo]
5 300
to}
a

TENSION

TERINE PR

600

z 400

E 200

THT |

out

* 2885
BABOON
ft./sec.

>|

Fier

6

| 0.0! Sec.

Results of inpact test No. 3 (Daisy Run No, 2885).



Intraiterine maternal TEIG. fetal
ERG, wid maternal blood pressure were recorded
with an Schannel Sanborn and Ampex CF 100

In all
toring failed at impact, and post-

pressure,

tape recor! oy jastnces, waternal blood
pressure
pact ¢

periodic = oy ss

dthis variable were obtained by
nometer readings, In addi-
vartables, Consolidated
Electrodynandes Css of the
Wri tae geprofile were recorded.

tion to the. pa .

jon tracings

seat bely tensions
lateral

documentation included

Huu. tiotion picture at 2.000 tps.

Phetographis

and overhead 16

black-and-white still coverage of pre-and post-
run procedures, and 3% min. color photographs
of gross trauma, ‘To study body organ displace-

Field) Brutssion Flexitron

wis Urivgeved at 0.087

ment at impact a

Flash X-ray Systeni see.

Baboon restraint chass aod 71 study

led moverient su that ar

after entrance of the sled into the water brah
Post-run whole body X
animal.

‘The

hiques, test procedures.

Ve owere ttken on each

purpose of Test £ was to establish tech-

tha deceleration patterns

for subsequent experiments, ‘The subject was
hot pregnant and physiological mouitoring was:
not attempted. “The subjects of ‘Tests 21 were

also nonpregtant but. in these aulmals. a simu-

lated uterus was iiiphuited. Phe latter cousisted
of a rubber balloow enclosed in nylon uerding
and contained a transducer to measure pressure
eh
ficient fluid) (approximately Ab00 ce,
haseline pressure to lo nun, ILy.

In

ierus was opened and the

ves during deceleration. Tt contained sut-

Sa-

nornial
line) to give
For
these

Tests 5 nant females were used.

anin

in caikly aid shoulder restraints designed to release at onset of
jaar ean “jackkuife

normally at i

ypuet


IMPACT INJURY TO THE PREGNANT FEMALE AND FETUS
BELT RESTRAI

I. Introduction.

The lap (seat) belt offers considerable pro-
tection against injury in impact accidents, al-
though little is known of its effects on the
pregnant mother and her fetus.!| In the United
States, most women travel by automobile at one

time or another during their pregnancy. A
large number also travel as passeng in com-

mercial or private aireraft and, as dependents.
on planes of the Miliary Airlift Commande?”
The present study was initiated to determine
the effects of abrupt deceleration on the mother
and her fetus when restrained by a Jap belt.

To our knowledge. only one such ease, involy-
ing a woman in the sixth month of pregnancy.
has been reported in the literature.’ This pa-
tient, with her seat belt properly secured, was
riding in the front passenger seat of an auto-
mobile traveling about 35 mph when it was
struck from the right front by another car.
Surgical exploration revealed a 6 em, laceration
of the uterus through which the fetus had been
expelled by the force of the impact. A dead
fetus was delivered and the mother survived.
Unfortunately, the risk of exposure and fre-
quency of this (ype of accident cannot yer be
d due to the absence of any reliable sta-
tistical data. Some indication of the scope of
the problem can be gained from the fact that we
have been able to collect 15 sueh cases in the
course of a 2-month etfort. of these re-
sulted in fetal demise. While relatively rare at
the present time. we ean expect them: to become
more frequent as the seat belt gains wider ac-
ceptance by the traveling public.

Paper presented, 10th Stapp Car ¢
University of Minnesota, July, 1907.

hh Conference,

The data presented here constitute the tirst
experimental approach to the subject.
II. Material and Methods.

For this study. a series of seven animal impact

tests was conducted on the Daisy Deceleration

LAP

ack at Holloman AFB. New Mexico. Female
Kenya baboons® (Pupio doguera) wore utilized
This primate has a
uterus simplex and a gestation period of about

as experimental animals.

180 days. The adult females average about 13 kg.
in body weight and a full-term infint may weigh
400-100 erunis.

A-seat scaled to fit the baboon was constructed
(Figs. 1. The seat was oriented in the 45
(45-0) forward facing: position. A
lite seat cushion was added to prevent iliac frac-
ture. The seat belt consisted of 114 in.. 4500 Ib.
test nylon webbing, adjusted statically on the
seated animal to 1.5 (Fig. 3) by a tensiomecer.
Strain gauges were mounted on each side of the
lap belt. Belt angle was 53°. typieal of com-
mercial installation, AC standard 14 x 17 in,
X-ray cassette was mounted on the left side of
the sea. Animals were restrained in modified
children’s denim jackets.

in. ons

To date. seven tests involving six animals have
been conducted. In addition. a sham test (with
out a sled run) was performed as a control of
artifacts due to surgical and pre-ran restraint
procedure, In Test 1 and in the sham test.
SernalynTM (Parke, Davis and Co.) anaesthesia
was employed at a dosage of 1 mg.kg. body
tf, administered intramuseukuly.  Innovar-
Vet! (McNeil Laboratories. Ine.) was used for
anaesthesia in ‘Tests
Tn Test 7

ku. body we

in 1.5 ce. intramuscular

dosages, Nembutal in a dosage of

Ba me rh, wa

teed in an attempt
to avoid the known adrenergic effects of Innovir
Veto In all approximuuely 4 hours
elapsed between initial anaesthesia and impact.
so that some measure of normal muscle tonus
was regained.

Costs,

*The animals used for these experiments were law
Cully aeqnived and treated in accordance with the
Jrinciples of Laboratory Animal Care issued by the
Animal Pacilities Standards Conanittee of the Animal
fare Panei, U.S. Deparcuent of Health, Education, and
Welfare, Public Healt: Service, Mattel 1968,



ACKNOWLEDGMEN'

The authors gratefully acknowledge the assistance of M. C. Oviatt, Chief.
rch Engineering. Civil Aeromedical Institute, who assisted with the
design of the seat, specialized equipment. and physiological measurenients

Rese

throughout the tests: Robert Goodin, Land-Air, Dyno-Electron Corp... who
shot and processed all. X-rays; William ‘Taylor, Land-Air Photographer:

and Dr. Richard Sonntag, who volunteered much valuable assistance.

Quillified requesters nay obtiin Aviation Medieat Rep
Center, ‘The general public may pure
Technical Information, U

ris from Defense Documentation
aise from Clearinghouse for Federal Scientific and
Held, Va. 51

Dept. of Commerce, Spri