Michele Grimm - Profile on Academia.edu (original) (raw)

Papers by Michele Grimm

Use of ultrasound attenuation and velocity to estimate Young's modulus in trabecular bone

Measurements were made of ultrasound transmission velocity (UTV) and attenuation (BUA) in cores o... more Measurements were made of ultrasound transmission velocity (UTV) and attenuation (BUA) in cores of human trabecular bone. The Young's modulus and apparent density were also determined for each specimen. Analysis of the correlation between the ultrasonic parameters and the mechanical property was conducted. The highest coefficient of determination was found for a linear combination model of UTV and BUA. It

Journal of biomechanical engineering, Feb 19, 2021

The biomechanical process of childbirth is necessary to usher in new lives-but it can also result... more The biomechanical process of childbirth is necessary to usher in new lives-but it can also result in trauma. This physically intense process can put both the mother and the child at risk of injuries and complications that have lifelong impact. Computational models, as a powerful tool to simulate and explore complex phenomena, have been used to improve our understanding of childbirth processes and related injuries since the 1990s. The goal of this paper is to review and summarize the breadth and current state of the computational models of childbirth in the literature-focusing on those that investigate the mechanical process and effects. We first summarize the state of critical characteristics that have been included in computational models of childbirth (i.e., maternal anatomy, fetal anatomy, cardinal movements, and maternal soft tissue mechanical behavior). We then delve into the findings of the past studies of birth processes and mechanical injuries in an effort to bridge the gap between the theoretical, numerical assessment and the empirical, clinical observations and practices. These findings are from applications of childbirth computational models in four areas: (1) the process of childbirth itself, (2) maternal injuries, (3) fetal injuries, and (4) protective measures employed by clinicians during delivery. Finally, we identify some of the challenges that computational models still face and suggest future directions through which more biofidelic simulations of childbirth might be achieved, with the goal that advancing models may provide more efficient and accurate, patient-specific assessment to support future clinical decisionmaking.

Design as a Feature of Biomedical Engineering Education—Satisfying ABET and Preparing Students to Address Clinical Needs

Journal of biomechanical engineering, Sep 22, 2020

Design is an important aspect of biomedical engineering education. It prepares students to work a... more Design is an important aspect of biomedical engineering education. It prepares students to work as part of a team to develop systems that address medical and health-related needs—and it is required to be part of an accredited undergraduate engineering program. This work looks at the history of design requirements in the U.S. and the current state of biomedical engineering curricula with respect to design. As a growing number of programs have expanded their design program beyond the capstone project, some examples of innovative programs are described. There is no single way to address design education within an undergraduate biomedical engineering program. However, intentional development of this component of the curriculum can enhance the impact on student learning and outcomes.

American Journal of Obstetrics and Gynecology, Dec 1, 2003

The incidence of Cesarean delivery (CD) is increasing in the US. Our purpose was to determine the... more The incidence of Cesarean delivery (CD) is increasing in the US. Our purpose was to determine the relative influence of pregravid obesity and diabetes on CD risk. STUDY DESIGN: Singleton pregnancies eligible for a trial of labor at our urban center 1/1997-6/2001 were evaluated. Subjects were defined by pregravid body mass index (BMI) as underweight (< 19.8kg/m 2), normal (19.8-25kg/m 2), overweight (25.1-30kg/m 2), and obese (>30kg/m 2). Diabetes (DM) in pregnancy was divided into insulin-(IDM) and non-insulin-(NIDM) treated. Deliveries < 23 weeks EGA or with prior CD were excluded. The risk of CD was evaluated for each group, stratified by EGA (term, preterm, total). Multivariate analysis examined the influence of DM, macrosomia (BWT>4500gms), labor induction, and parity on CD risk. RESULTS: This study included 12,303 deliveries [2828 (22.9%) overweight, 2605 (21.2%) obese, 46 (0.4%) NIDM, and 197 (1.6%) IDM]. The CD rate was 9.6%. Compared to non-obese subjects, CD risk was higher in obese (13.8 v 7.3% RR = 1.9, p < 0.0001) and overweight women (12.6 v 7.8% RR = 1.6, p < 0.0001). Low BMI protected against CD (6.2 v 10.2% RR = 0.6, p = 0.04). NIDM (21.7 v 9.5% RR = 2.3, p = 0.01) and IDM (29.9 v 9.2% RR = 3.3, p < 0.0001) also increased CD risk. Other CD risk factors included macrosomia (25 v 9.4% RR = 2.7, p < 0.0001), nulliparity (16.5 v 4.7% RR = 2.3, p < 0.0001), induction (17.4 v 8.3% RR = 2.1, p < 0.0001), and Black Race (10.7 v 8.8% RR = 1.2, p < 0.0001). Multiple regression of term deliveries revealed obesity (OR 2.5 p < 0.0001) and IDM (OR 2.1 p < 0.0001) to be most highly correlated to CD risk, and NIDM not to be an independant risk factor (OR 2.5 p = 0.06). Given the high incidence of obesity in this population (37.8%) and the relative infrequency of IDM, maternal obesity has more impact on the overall risk of CD in our population than IDM. CONCLUSION: Maternal obesity and insulin-treated diabetes independently increase CD risk. Given the high prevalence of obesity, maternal body habitus may exert a disproportionate influence on CD rates.

American Journal of Obstetrics and Gynecology, Apr 1, 2003

A computer model was modified to study the impact of maternal endogenous and clinician-applied ex... more A computer model was modified to study the impact of maternal endogenous and clinician-applied exogenous delivery loads on the contact force between the anterior fetal shoulder and the maternal symphysis pubis. STUDY DESIGN: Varying endogenous and exogenous loads were applied, and the contact force was determined. Experiments also examined the effect of pelvic orientation and the direction of load application on contact force behind the symphysis pubis. RESULTS: Exogenous loading forces (50-100 N) resulted in anterior shoulder contact forces of 107 to 127 N, with delivery accomplished at 100 N of applied load. Higher contact forces (147-272 N) were noted for endogenously applied loads (100-400 N), with delivery occurring at 400 N of maternal force. Pelvic rotation from lithotomy to McRoberts' positioning resulted in reduced contact forces. Downward lateral flexion of the fetal head led to little difference in contact force but required 30% more exogenous load to achieve delivery. CONCLUSION: Compared with clinician-applied exogenous force, larger maternally derived endogenous forces are needed to clear the impacted anterior fetal shoulder. This is associated with >2 times more contact force by the obstructing symphysis pubis. McRoberts' positioning reduces shoulder-symphysis pubis contact force. Lateral flexion of the fetal head results in the larger forces that are needed for delivery but has little effect on contact force. Model refinements are needed to examine delivery forces and brachial plexus stretching more specifically.

Potential role of nuclear magnetic resonance for the evaluation of trabecular bone quality

Calcified Tissue International, Feb 1, 1993

This paper discusses two novel applications of nuclear magnetic resonance (NMR) as an investigati... more This paper discusses two novel applications of nuclear magnetic resonance (NMR) as an investigational tool for the assessment of cancellous bone microarchitecture. It further outlines extensions of the method for in vivo clinical evaluation of bone strength in patients with skeletal disorders such as osteoporosis. The first method relies on the hypothesis that the presence of two phases of different magnetic permeability, i.e., bone and bone marrow, causes a spatial nonuniformity of the magnetic field across the measurement volume. The resulting spread in resonance frequency shortens the decay time constant (T2*) of the time domain proton signal in bone marrow or its substitute (water). Increased trabecular spacing, such as it occurs in osteoporosis, reduces the spatial field inhomogeneity and thus prolongs T2*, which has been shown both in vitro and in vivo. Subjects with osteoporosis, characterized by either low bone mineral density and/or spine compression fractures, have T2* values that are significantly prolonged. The second method focuses on a direct measurement of micromorphometric parameters of cancellous bone, using the principles of proton NMR microscopy in conjunction with computer processing of the resulting digital images. Image contrast between the trabeculae and the intertrabecular space is based on the marrow protons providing a signal, as opposed to bone, which appears with background intensity. Once tissues have been classified (into bone and marrow), for example, by means of a histogram-based segmentation algorithm, bone area fraction, mean trabecular plate density (MTPD), and mean trabecular plate thickness (MTPT) can be computed without the need for further operator intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

American Journal of Obstetrics and Gynecology, Oct 1, 2010

The objective of the study was to determine how standard shoulder dystocia maneuvers affect deliv... more The objective of the study was to determine how standard shoulder dystocia maneuvers affect delivery force and brachial plexus stretch. STUDY DESIGN: A 3-dimensional computer model of shoulder dystocia was developed, including both a fetus and a maternal pelvis. Application of suprapubic pressure, rotation of the infant's shoulders, and delivery of the posterior arm following shoulder dystocia were each modeled, and delivery force and brachial plexus stretch were predicted. RESULTS: Compared with lithotomy alone, all maneuvers reduced both the required delivery force and brachial plexus stretch. The greatest effect was seen with delivery of the posterior arm, which showed a 71% decrease in anterior nerve stretch (3.9% vs 13.5%) and an 80% decrease in delivery force. CONCLUSION: The standard maneuvers met the objective of reducing the necessary delivery force compared with the lithotomy position alone. Brachial plexus stretch is also reduced when these maneuvers are used rather than continuing the delivery in lithotomy position.

Ultrasound Propagation Through the Calcaneus: Dependence on "bone Quality" and Prediction by Biot's Theory

Sensors, Sep 26, 2022

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

American Journal of Obstetrics and Gynecology, Mar 1, 2000

Detroit, Michigan OBJECTIVE: A mathematic model was developed to estimate the compressive pressur... more Detroit, Michigan OBJECTIVE: A mathematic model was developed to estimate the compressive pressure on the fetal neck overlying the roots of the brechial plexus by the symphysis pubis during a shoulder dystocia event. The induced pressure was calculated for both exogenous (clinician applied) and endogenous (maternal and uterine) forces during the second stage of labor. STUDY DESIGN: Intrauterine pressure and clinician-applied force data were taken from the existing literature. A free-body diagram was generated and equilibrium equations were used to calculate the contact pressure between the bass of the fetal neck and the symphysis pubis during a shoulder dystocia event. RESULTS: Clinician-applied traction to the fetal head (exogenous force) led to an estimated contact pressure of 22.9 kPa between the fetal neck and the symphysis pubis. In contrast, uterine and maternal expulsive efforts (endogenous forces) resulted in contact pressures that ranged from 91.1 to 202.5 kPa. The estimated pressures resulting from endogenous forces are 4 to 9 times greater than the value calculated for clinicianapplied forces. CONCLUSION: Neonatal brachial plexus injury is not a priori explained by iatrogenically induced excessive traction. Spontaneous endogenous forces may contribute substantially to this type of neonatal trauma.

How to Build Your Mentoring Tree—Insight Gained From a 36-Year Career in Biomedical Engineering

Journal of biomechanical engineering, May 22, 2023

Mentoring is often viewed as a unidirectional relationship, with the senior, more seasoned indivi... more Mentoring is often viewed as a unidirectional relationship, with the senior, more seasoned individual imparting knowledge, guidance, and experience to more junior individuals. But this structure limits our ability to recognize that the mentoring relationship can bring benefits and opportunities for growth to the mentor as well. On the occasion of receiving the 2022 Robert M. Nerem Education and Mentorship Medal, I have had the opportunity to reflect on the mentoring that I have been lucky enough to participate in—both as mentor and mentee—during my academic career. This paper discusses some of those insights and presents the concept of a mentoring tree—through which we can identify multiple mentors and mentees, each of whom can provide mutual support and insight as we progress through our careers. Each individual who is part of our mentoring tree can play a role at different times and with different challenges within our professional path. This everchanging and growing structure provides continuous mentoring without overtaxing any single relationship.

489 Defining forces associated with shoulder dystocia (SD): Use of a dynamic computer model (MADYMO)

American Journal of Obstetrics and Gynecology, Dec 1, 2001

Forces Involved with Labor and Delivery—A Biomechanical Perspective

Annals of Biomedical Engineering, Jan 11, 2021

Childbirth is a primarily biomechanical process of physiology, and one that engineers have recent... more Childbirth is a primarily biomechanical process of physiology, and one that engineers have recently begun to address in a broader fashion. Computational models are being developed to address the biomechanical effects of parturition on both maternal and fetal tissues. Experimental research is being conducted to understand how maternal tissues adapt to intrauterine forces near the onset of labor. All of this research requires an understanding of the forces that are developed through maternal efforts-both uterine contractions and semi-voluntary pushing-and that can be applied by the clinician to assist with the delivery. This work reviews the current state of knowledge regarding forces of labor and delivery, with a focus on macro-level biomechanics.

Clinical Obstetrics and Gynecology, Dec 1, 2016

Childbirth is a complicated biomechanical process that many take for granted. However, the delive... more Childbirth is a complicated biomechanical process that many take for granted. However, the delivery forces generated by a mother (uterine contractions and maternal pushing) are strong and have a significant effect on the body and tissues of the fetus, especially during the second stage of labor. Although most infants are born without negative, force-related outcomes, in some infants the normal forces of labor cause an injury that can have either temporary or permanent sequelae. The biomechanical situation is further complicated when an infant's shoulder impacts the maternal pelvis, which provides increased resistance and creates added stresses within the neonatal body and tissues.

Prediction of frequency and pore size dependent attenuation of ultrasound in trabecular bone using Biot’s theory

Solid mechanics and its applications, 1996

Biot’s theory is applied to trabecular bone using the Johnson-Koplik-Dashen (JKD) theory of perme... more Biot’s theory is applied to trabecular bone using the Johnson-Koplik-Dashen (JKD) theory of permeability and tortuosity. This may be the first instance in which the critical physical constants for bone, as determined from experiments, are used with Biot’ theory, incorporating the JKD permeability and tortuosity, to calculate velocities and attenuations and compare the results with experimentally determined velocities and attenuations. The velocities are correctly predicted by the theory and there is qualitative agreement with the experimental attenuations. The predicted magnitudes of the attenuations calculated for internal Biot losses due to relative motion of the solid and fluid phases are smaller than the experimentally measured attenuations, which include losses due to porous surface reflection at the front and back of the specimen, scattering due to macroscopic pores, as well as attenuation due to intrinsic losses in the bone and in the marrow phase, which are not directly accounted for by Biot’s theory.

Clinical Biomechanics, Jul 1, 1997

Objective. To determine if ultrasound measurements in the heel are related to bone quality in add... more Objective. To determine if ultrasound measurements in the heel are related to bone quality in addition to quantity. Design. In situ and in vitro experiments on cadaver heels. Background. It has been suggested, but not demonstrated, that clinical ultrasound-used to screen for osteoporosis in clinical trials-provides a measure of 'bone quality' as distinct from bone quantity. Methods. Ultrasound transmission velocity (UTV) and the slope of the linear dependence of broadband ultrasound attenuation on frequency (BUA) were measured in situ in 32 heels of 16 cadavers and in vitro in cores of calcaneal trabecular bone. Results. After adjusting for Young's modulus, in situ UTV explains 33% (P = 0.03) and in situ BUA explains none of the remaining variance in density (r* = 0.02, P = 0.60). After adjusting for density, in situ BUA explains 29% (P = 0.04) and in situ UTV explains none of the remaining variance in Young's modulus (I-* = 0.01, P = 0.79). By comparison, in vitro BUA explains 58% (P = 0.001) of the remaining variance in Young's modulus, after adjusting for density. Conclusions. In situ BUA reflects 'bone quality' independently of bone quantity, whereas in situ UTV reflects bone quantity independently of 'bone quality'. Relevance The results show that clinical ultrasound is associated with mechanical 'bone quality' in addition to quantity, but the full potential of ultrasound exhibited in vitro may not be realized in situ without improvements in ultrasound technology.

Work in Progress: Creative Biomechanics Project Using an Interactive Digital Experience as an Alternative Laboratory (IDEAL) – Phase 2

2021 ASEE Virtual Annual Conference Content Access, Jul 26, 2021

The effect of clinician-applied maneuvers on delivery force and brachial plexus strain during shoulder dystocia deliveries — assessment through mathematical modeling

Journal of Biomechanics, 2006

Journal of therapeutic ultrasound, Nov 1, 2013

Background: The primary goal of this study was to investigate the relationship between increasing... more Background: The primary goal of this study was to investigate the relationship between increasing output power levels and clot fragmentation during high-intensity focused ultrasound (HIFU)-induced thrombolysis. Methods: A HIFU headsystem, designed for brain applications in humans, was used for this project. A human calvarium was mounted inside the water-filled hemispheric transducer. Artificial thrombi were placed inside the skull and located at the natural focus point of the transducer. Clots were exposed to a range of acoustic output power levels from 0 to 400 W. The other HIFU operating parameters remained constant. To assess clot fragmentation, three filters of different mesh pore sizes were used. To assess sonothrombolysis efficacy, the clot weight loss was measured. Results: No evidence of increasing clot fragmentation was found with increasing acoustic intensities in the majority of the study groups of less than 400 W. Increasing clot lysis could be observed with increasing acoustic output powers. Conclusion: Transcranial sonothrombolysis could be achieved in vitro within seconds in the absence of tPA and without producing relevant clot fragmentation, using acoustic output powers of <400 W.

Journal of Biomechanical Engineering

Computational modeling serves an important role in childbirth-related research. Prescribed fetal ... more Computational modeling serves an important role in childbirth-related research. Prescribed fetal descent trajectory is a key characteristic in childbirth simulations. Two major types of fully prescribed fetal descent trajectories can be identified in the literature: straight descent trajectories and curve of Carus. The straight descent trajectory has the advantage of being simpler and can serve as a reasonable approximation for relatively small fetal movements during labor, but it cannot be used to simulate the entire childbirth process. The curve of Carus is the well-recognized fetal descent trajectory with physiological significance. However, no detailed procedure to geometrically define the curve of Carus can be found in existing computational studies. This status of curve of Carus simulation in the literature hinders the direct comparison of results across different studies and the advancement of computational techniques built upon previous research. The goals of this study are:...