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T J Kriewall

Publications and source records attributed to T J Kriewall.

13 recordsLinked to original sources
PubMed1986

Mechanical behavior of fetal dura mater under large deformation biaxial tension.

The mechanical behavior of fetal dura mater was investigated by means of a biaxial tension test designed to simulate the constraints imposed on the membrane by the cranial bones. The experimental results are compared with the theoretical results obtained by using two published strain energy functions: one defined by Mooney and Rivlin (MR) and the other by Skalak, Tozeren, Zarda and Chien (STZC). The latter constitutive relations fit the experimental results consistently well. The STZC stiffness values from this series of tests are compared with those from membrane inflation tests performed previously and reported elsewhere by the authors.

Biomechanical Phenomena↗
PubMed1983

Mechanical behavior of fetal dura mater under large axisymmetric inflation.

The nonlinear mechanical behavior of fetal dura mater was tested experimentally and compared to two published nonlinear material strain energy functions, the Mooney-Rivlin and the Skalak, Tozeren, Zarda, and Chien (STZC). The STZC constitutive relations best fit the behavior of the dura mater and were used to describe quantitatively its stiffness. Runge-Kutta numerical procedures were used to fit the theoretical data to the experimental results. The material's stiffness was positively correlated with fetal weight (r = 0.67, p less than 0.05). These results are discussed and directions for future research indicated.

Biomechanical Phenomena↗
PubMed1982

Structural, mechanical, and material properties of fetal cranial bone.

The structural stiffness of 20 parietal bones from 10 fetal cadavers were tested under controlled laboratory settings. The slope at the onset of the load-deflection curve dictated the stiffness of the bone. These values were correlated with the bone's modulus of elasticity, mineral content, and bone density, as well as with anthropometric data. The stiffness exhibited as much as a Anthropometric factors correlated more with the change in stiffness than did material factors, such as changes in modulus, mineral content, and bone density. The bone exhibited a pronounced fiber orientation which significantly affected the modulus of the test specimens. The results are discussed in terms of obstetric management of preterm and term labor.

Biomechanical Phenomena↗
PubMed1979

Experimental pneumothorax detected by thermography.

After induction of pneumothorax in rabbits, thermograms showed decreased heat emission from the involved side. These observations suggest that noninvasive monitors of thoracic wall temperatures might be useful for early detection of air-leak phenomenon in high-risk neonates.

Animals↗
PubMed1976

Uterine work in parturition.

This paper presents a theoretical analysis relating work expended by the uterus to the synergistic relationship between intrauterine pressure (IUP) and cervical dilatation (CD). By utilizing a geometrical model for the fetal presenting part which is assumed to be in contact with the cervix, the changes in internal volume of the uterus with each contraction can be shown to be functionally related to cervical dilatation. Thus work, expressed in terms of foot-pounds, can be calculated using the integral of pressure times incremental volume. By simulating intrauterine pressure and cervical dilatation with continuous analytical wave forms, the alterations required in uterine work to dilate the cervix are calculated for various wave-form aberrations which are seen in clinical situations. The wave-form aberrations are applied to an elastic cervical model as well as a viscoelastic model. Using the principles of thermodynamics the areas of the fetouterine complex which absorb the work generated by the contractions are defined. It is shown that the efficiency of the contractions to dilate the cervix can be calculated by evaluating the work expended in these various areas of energy absorption. The purpose of this paper is to present the theory upon which clinical findings in obstetrics can be based so that conclusions drawn will be technically sound.

Cervix Uteri↗
PubMed1975

The fever index: A technic for evaluating the clinical response to bacteremia.

The fever index, quantitative measure of the total amount of fever in degree hours, was determined in obstetric-gynecologic patients with bacteremia. Comparison of the mean fever index between those women with hospital-or community-acquired infections, those patients monitored or not monitored during labor, or by grouping of single organisms recovered by culture revealed no significant differences. Bacteremia patients over the age of 40 had significantly more fever than those under the age of 40. Patients with postpartum with postpartum bacteremia following cesarean section had a mean fever index significantly greater than women who had vaginal delivery. The implications of these findings are discussed.

Adult↗
PubMedDate not supplied

Measuring cervical dilatation in human parturition using the Hall effect.

An instrument was developed to continuously measure cervical dilatation in human labor. The instrument utilizes a small magnetic field source, which is attached to one edge of the cervix while a magnetic field sensor is attached to the diametrically opposite edge of the cervix. The sensor, using two Hall generators, measures orthogonal components of the field to minimize the effects of angular orientation between the source and sensor. The instrument's characteristics indicate that it can measure dilation throughout the range of 1-10 cm, but because its clinical reliability is consistent from only 1-7 cm, the equipment needs to be improved in the ways outlined in the text. This measurement, especially when analyzed with the continous measurement of intrauterine pressure, can provide the obstetrician with new insight into the physiology of labor.

Cervix Uteri↗