Automobile crash simulation with the first pregnant crash test dummy,☆☆,

Presented at the Sixteenth Annual Meeting of the Society of Perinatal Obstetricians, Kamuela, Hawaii, February 4-10, 1996.
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Abstract

OBJECTIVE: Our goal was to develop a pregnancy insert for the Hybrid III (First Technology, Farmington, Mich.) crash dummy allowing evaluation of the effects of various restraint conditions on energy transmission to both the fetal and maternal compartments. STUDY DESIGN: A pregnancy insert with an elasticized vinyl uterine shell, simulated silicon amniotic fluid, and a 28-week simulated fetus was fitted to a female crash dummy. The fetus was instrumented with accelerometers in the head and thorax and a transducer to measure force transmission through the uterus. Thirty-nine crash tests were run under six different restraint conditions at speeds ranging from 10 to 25 miles/hr. Fetal responses were compared for different restraint conditions. RESULTS: Increasing speed of the crash resulted in greater force transmission through the uterus. Placement of the lap belt over the uterus instead of under the uterus resulted in a threefold to fourfold increase in force transmission through the uterus at all speeds tested. Air bag deployment in the unbelted or out-of-position dummy (laying against air bag) appears to impart significant energy transmission to the fetus. CONCLUSIONS: Energy transmission can be measured in terms of both abdominal force and acceleration within the fetal head and thorax. This new dummy demonstrates substantial transmission of energy, which is accentuated in some restraint conditions commonly used by pregnant women. The use of the 3-point restraint system appears to reduce the likelihood of injury in this model. (Am J Obstet Gynecol 1996;175:977-81.)

Section snippets

MATERIAL AND METHODS

A pregnancy insert was developed to be placed in the pelvic region of the 5th percentile (height and weight) Hybrid III female anthropomorphic test device. To accommodate the pregnancy insert the anterior surface of the pelvic ring and the base of the lumbar spine were machined with approximately a 10 cm radius to allow insertion of the fetal assembly.

RESULTS

With seat belts placed in the positions recommended by The American College of Obstetricians and Gynecologists and the National Highway Traffic Safety Administration during pregnancy,2 higher-speed crashes resulted in larger accelerations within the fetal head and thoracic components and greater force transmission through the uterus (Fig. 3). The effect of improper placement of the lap belt on force transmission through the uterus was evaluated in a series of sled runs ranging from 10 to 25

COMMENT

Despite the implementation of various protocols to manage the pregnant woman after motor vehicle crashes, pregnancy loss occurs after relatively minor accidents without apparent maternal injury.3, 4, 5 Because most motor vehicle crashes are minor, most pregnancy losses occur after minor motor vehicle crashes. It is apparent from these facts that an improved understanding into the mechanism of pregnancy loss after motor vehicle crashes is an important first step in developing automobile

Acknowledgements

We gratefully acknowledge the skills and work that Joe Smrcka (deceased) of First Technologies, Inc., put into the physical development of the test device used in these experiments.

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From the Department of Obstetrics and Gynecology, University of Michigan Medical Center,aand General Motors Corporation.b

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Reprint requests: Mark Pearlman, MD, 1500 E. Medical Center Dr., D2202 MPB, Ann Arbor, MI 48109-0718.

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