Use of a mechanical simulator to assess pelvic examination skills.
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Clinical Competence↗
Biomedical subjects
T M Krummel
Publications and source records attributed to T M Krummel.
Virtual reality: surgical application--challenge for the new millennium.
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Algorithms↗
Trocar injuries in laparoscopic surgery.
BACKGROUND: Disposable trocars with safety shields are widely used for laparoscopic access. The aim of this study was to analyze risk factors associated with injuries resulting from their use as reported to the Food and Drug Administration. STUDY DESIGN: Manufacturers are required to report medical device-related incidents to the Food and Drug Administration. We analyzed the 629 trocar injuries reported from 1993 through 1996. RESULTS: There were three types of injury: 408 injuries of major blood vessels, 182 other visceral injuries (mainly bowel injuries), and 30 abdominal wall hematomas. Of the 32 deaths, 26 (81%) resulted from vascular injuries and 6 (19%) resulted from bowel injuries. Eighty-seven percent of deaths from vascular injuries involved the use of disposable trocars with safety shields and 9% involved disposable trocars with a direct-viewing feature. The aorta (23%) and inferior vena cava (15%) were the vessels most commonly traumatized in the fatal vascular injuries. Ninety-one percent of bowel injuries involved trocars with safety shields and 7% involved direct-view trocars. The diagnosis of an enterotomy was delayed in 10% of cases, and the mortality rate in this group was 21%. In 41 cases (10%) the surgeon initially thought the trocar had malfunctioned, but in only 1 instance was malfunction subsequently found when the device was examined. The likelihood of injury was not related to any specific procedure or manufacturer. CONCLUSIONS: These data show that safety shields and direct-view trocars cannot prevent serious injuries. Retroperitoneal vascular injuries should be largely avoidable by following safe techniques. Bowel injuries often went unrecognized, in which case they were highly lethal. Device malfunction was rarely a cause of trocar injuries.
Abdominal Muscles↗
Use of a human patient simulator in the development of resident trauma management skills.
BACKGROUND: Computerized human patient simulators (HPSs) have been used to improve diagnostic and therapeutic decision making. The goal of this study was to investigate the impact of HPSs and Advanced Trauma Life Support (ATLS) on the development of trauma management skills and self-confidence in surgical interns. METHODS: Three teams of interns completed two ATLS-like trauma scenarios on the HPS (pre-ATLS). They then took the ATLS provider course. After ATLS, the interns were evaluated on two different HPS trauma scenarios (post-ATLS). Two teams of senior residents, experienced in trauma care, completed the same HPS scenarios and were used as controls. Trauma management skills were scored in three areas--critical treatment decisions, potential for adverse outcomes, and team behavior--by staff trauma surgeons. After participating in the HPS trauma scenarios, the interns completed self-confidence questionnaires and a course evaluation survey. RESULTS: Trauma management skill scores increased 23% in critical treatment decisions, 25% in potential for adverse outcomes, and 47% in team behavior after ATLS/HPS (p < 0.002). Senior residents' performance on HPS trauma scenarios was better than the interns (p < 0.05) in all three areas evaluated. The interns' self-confidence scores rose significantly after the course. (p < 0.01) The HPS course evaluation survey averaged 8.3 out of a maximum 10. CONCLUSION: Use of HPSs in conjunction with ATLS appears to enhance the development of trauma management skills. The surgical interns participating in the study deemed the HPS to be a worthwhile experience and a confidence-building tool. In particular, trauma team behavior improved significantly after ATLS/HPS.
Clinical Competence↗
Computers and virtual reality for surgical education in the 21st century.
Surgeons must learn to perform operations. The current system of surgical resident education is facing many challenges in terms of time efficiency, costs, and patient safety. In addition, as new types of operations are developed rapidly, practicing surgeons may find a need for more efficient methods of surgical skill education. An in-depth examination of the current learning environment and the literature of motor skills learning provides insights into ways in which surgical skills education can be improved. Computers will certainly be a part of this process. Computer-based training in technical skills has the potential to solve many of the educational, economic, ethical, and patient safety issues related to learning to perform operations. Although full virtual-reality systems are still in development, there has been early progress that should encourage surgeons to incorporate computer simulation into the surgical curriculum.
Clinical Competence↗
Computer-assisted training and learning in surgery.
The teaching and learning of surgery is a time-honored tradition based upon the "see one, do one, teach one" apprenticeship model. Recent improvement of this model has centered upon incremental change in skills teaching and testing and curricular development. Economic pressures have strained the resources of academic health centers and faculty responsible for teaching surgery, even as information technology has opened new avenues for obtaining and benefitting from relevant information. Combining the tools of simulation theory, virtual reality, and the principles of adult education offers new opportunities to optimize surgical education as we enter a more highly connected and interdependent era, where the boundaries between teacher and student blur as the modern surgeon truly becomes a lifelong learner.
Computer Simulation↗
Practical training for postgraduate year 1 surgery residents.
BACKGROUND: Surgical interns accept significant patient care responsibilities with minimal orientation. We have developed a multifaceted training program for incoming surgical interns in which learning in a simulated environment plays a key role. The purpose of this study was to evaluate resident perceptions of simulated clinical calls as an educational modality and to measure the effect on self-ratings of confidence. METHODS: A multidisciplinary team compiled 15 clinical scenarios. Simulated nurse-to-resident clinical call sessions were held on 3 separate days. Daily course evaluation surveys and identical precourse and postcourse confidence surveys were completed. RESULTS: The resident confidence measure increased significantly postcourse (6.73 versus 8.35, P <0.03). The evaluation survey score averaged 4.35 out of 5. CONCLUSIONS: Simulated clinical call sessions were well received and resulted in a significant increase in resident confidence levels. Based on this modality's apparent efficacy and ease of implementation, we offer it as a useful educational tool for incoming postgraduate year-1 surgical residents.
Attitude of Health Personnel↗
The future of medical education is no longer blood and guts, it is bits and bytes.
In the United States, medical care consumes approximately $1.2 trillion annually (14% of the gross domestic product) and involves 250,000 physicians, almost 1 million nurses, and countless other providers. While the Information Age has changed virtually every other facet of our life, the education of these healthcare professionals, both present and future, is largely mired in the 100-year-old apprenticeship model best exemplified by the phase "see one, do one, teach one." Continuing medical education is even less advanced. While the half-life of medical information is less than 5 years, the average physician practices 30 years and the average nurse 40 years. Moreover, as medical care has become increasingly complex, medical error has become a substantial problem. The current convulsive climate in academic health centers provides an opportunity to rethink the way medical education is delivered across a continuum of professional lifetimes. If this is well executed, it will truly make medical education better, safer, and cheaper, and provide real benefits to patient care, with instantaneous access to learning modules. At the Center for Advanced Technology in Surgery at Stanford we envision this future: within the next 10 years we will select, train, credential, remediate, and recredential physicians and surgeons using simulation, virtual reality, and Web-based electronic learning. Future physicians will be able to rehearse an operation on a projectable palpable hologram derived from patient-specific data, and deliver the data set of that operation with robotic assistance the next day.
Allied Health Personnel↗
A longitudinal analysis of the pediatric surgeon workforce.
OBJECTIVE: To describe the trends in the pediatric surgeon workforce during the last 25 years and to provide objective data useful for planning graduate medical education requirements. SUMMARY BACKGROUND DATA: In 1975, the Study on U.S. Surgical Services (SOSSUS) was published, including a model to survey staffing. A pediatric surgeon workforce study was initiated in conjunction with SOSSUS as a population, supply, and need-based study. The study has been updated every 5 years using the same study model, with the goals of determining the number and distribution of pediatric surgeons in the United States, the number needed and where, and the number of training programs and trainee output required to fill estimated staffing needs. This is the only such longitudinal workforce analysis of a surgical specialty. METHODS: Questionnaires were sent to 100 pediatric surgeons representing the 62 standard metropolitan statistical areas (SMSAs) in the United States with a population of 200,000 or more to verify the names and locations of all active pediatric surgeons and to gain information about the 5-year need for new pediatric surgeons by region. A program was developed to predict the number of pediatric surgeons relative to the total population and the 0-to-17-year-old population in the subsequent 30 years using updated data on the present number and ages of pediatric surgeons, age-specific death and retirement rates, projections of U.S. population by age group, and varying numbers of trainees graduated per year. As each 5-year update was done, previous projections were compared with actual numbers of pediatric surgeons found. The trends during the last 25 years were analyzed and compared and additional information regarding the demographics of practice, trends in reimbursement, and volume and scope of surgery was obtained. RESULTS: The birth rate has been stable since 1994. The 0-to-17-year-old population has been increasing at 0.65% per year; a 0.64% annual rate is projected to 2040. At present, 661 pediatric surgeons are distributed in every SMSA of 200,000 or more population, with an average age of 45 and an average age of retirement 65. The actual number of pediatric surgeons in each 5-year survey has consistently validated previous projections. Trainee output has increased markedly in the past 10 years. The rate of growth of the pediatric surgeon workforce at present is 50% greater than the forecasted rate of increase in the pediatric age group, and during the past 25 years the rate of growth of the pediatric surgeon workforce has been double that of the pediatric population growth. Nationally, significant changes in reimbursement, volume of surgery, and demographics of practice have occurred.
Adolescent↗
Dexamethasone enhances ras-recision gene expression in cultured murine fetal lungs: role in development.
We have shown that dexamethasone (Dex) accelerates maturation and differentiation of cultured fetal murine lungs (Cilley RE, Zgleszewski SE, Krummel TM, and Chinoy MR. Surg Forum 47: 692-695, 1996). We now demonstrate that although Dex inhibits thinning of acinar walls and secondary septa formation, it does, however, promote lung growth. CD-1 murine fetal lungs were cultured for 7 days in the presence and absence of 10 nM Dex. Dex-modulated genes were investigated and identified by differential display of mRNAs performed with specific anchor primer H-T(11)G and 24 arbitrary primers. Thirty-five differentially expressed cDNAs were isolated, subcloned, sequenced, and identified through BLAST searches. One of these cDNAs, termed Dex2, with enhanced expression in Dex-treated lungs, had 100% similarity with ras-recision gene (rrg), also known as the lysyl oxidase (LOX) gene that encodes lysyl oxidase. LOX gene is very highly conserved, with significant sequence similarity among mouse, rat, and human. Two other cDNAs, termed Dex1 and Dex4, were also identified as rrg, with 92 and 97% sequence similarity with the existing data bank sequence of rrg. LOX enzyme is known to downregulate p21(ras) protein and play a central role in the maturation of collagen and elastin in the extracellular matrix as well as modulate the cytoskeletal elements. Thus LOX may be important in lung developmental processes involving epithelial-mesenchymal interactions.
Animals↗
G2H--graphics-to-haptic virtual environment development tool for PC's.
For surgical training and preparations, the existing surgical virtual environments have shown great improvement. However, these improvements are more in the visual aspect. The incorporation of haptics into virtual reality base surgical simulations would enhance the sense of realism greatly. To aid in the development of the haptic surgical virtual environment we have created a graphics to haptic, G2H, virtual environment developer tool. G2H transforms graphical virtual environments (created or imported) to haptic virtual environments without programming. The G2H capability has been demonstrated using the complex 3D pelvic model of Lucy 2.0, the Stanford Visible Female. The pelvis was made haptic using G2H without any further programming effort.
Computer Graphics↗
End user analysis of a force feedback virtual reality based surgical simulator.
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Biomechanical Phenomena↗
Virtual body structures: a 3D structure development tool from visible human data.
Understanding the visiospatial aspects of anatomic structures is one of the most important aspects of studying gross anatomy. In this paper we are describing a tool that self-constructs 3D virtual body structures (VBS) 'right in-front-of your-eyes'. Furthermore, manipulation capabilities, such as translucent visualization, interactive rotation, translation, and scaling, incorporated into VBS facilitate fundamental learning experience that leads one to 'build 3D models in the mind', providing a validation of computer-assisted individual learning. Creating 3-D virtual body structures from actual human data has long been a dream of many computer scientists and Medical doctors. Now, with the advances in computer hardware and software technologies, our Virtual Body Structure technique, and the Visible Human project, that dream is becoming a reality.
Anatomy, Cross-Sectional↗
Simulation and virtual reality in surgical education: real or unreal?
Rapid change is under way on several fronts in medicine and surgery. Advances in computing power have enabled continued growth in virtual reality, visualization, and simulation technologies. The ideal learning opportunities afforded by simulated and virtual environments have prompted their exploration as learning modalities for surgical education and training. Ongoing improvements in this technology suggest an important future role for virtual reality and simulation in surgical education and training.
Computer Simulation↗
Effects of dexamethasone, growth factors, and tracheal ligation on the development of nitrofen-exposed hypoplastic murine fetal lungs in organ culture.
BACKGROUND/PURPOSE: The addition of growth factors EGF (epidermal growth factor) plus TGFbeta1 (transforming growth factor beta1; E + T) or dexamethasone (DEX) to normal murine fetal lungs in culture enhances lung development. In addition, ligation of the airway in lungs in organ culture, enhances lung development. Nitrofen (2,4-dichlorophenyl-p-nitrophenylether) administration to pregnant mice results in pulmonary hypoplasia in the offspring with many similarities to human hypoplastic lung conditions. This study investigates the effects of growth factors, dexamethasone, and airway ligation on the development of hypoplastic fetal murine lungs in whole-organ culture. We hypothesized that E+T, DEX, or airway ligation will enhance the development and maturation of hypoplastic murine fetal lungs in vitro. METHODS: Time-dated pregnant CD-1 mice were given nitrofen, 25 mg, intragastrically at gestational day (Gd) 8. The dams were killed on Gd 14, and the fetuses were removed. The hypoplastic fetal lungs were excised, and the tracheae were transected. The lungs were cultured in serum-free BGJb media in the presence or absence of E+T (10 ng/mL + 2 ng/mL, respectively) or DEX (10 nmol/L). Some lungs were cultured for 7 days with the tracheae ligated. RESULTS: Gross morphology under a dissecting stereomicroscope showed that the lungs were larger after E+T, DEX, or tracheal ligation. Histologically, the untreated lungs had progressed from the pseudoglandular stage to a canalicular-like stage with poorly differentiated airways. The E+T-treated lungs had better developed airway branching and small acini; however, thick mesenchyme persisted. The ligated lungs had well-developed airway branching and acinar structures. After DEX treatment the lungs were most developed with very well defined airway branching and expanded acinar structures; however, there was no secondary septation. Ultrastructurally, the hypoplastic lungs at Gd 14 and after 7 days in culture had no glycogen in their epithelial cells, no defined acinar formation, and had damaged mitochondria. The E+T-treated or tracheally ligated lungs had abundant type II cells, secreted lamellar bodies (LBs), and showed infrequent tubular myelin. Mitochondrial damage was noted in these lungs as in the untreated lungs. DEX-treated hypoplastic lungs showed large acini. The acinar walls were thick; however, they had type II cells with abundant LBs and intact mitochondria. The airways were noted to have differentiated cell types. Surfactant secretions in acinar spaces showed tubular myelin structures. CONCLUSIONS: E+T, tracheal ligation, or DEX accelerates lung development and maturation of hypoplastic fetal murine lungs compared with untreated controls. DEX had a greater effect with special reference to repair of mitochondrial damage. DEX not only accelerated lung development, but it may have reversed some of the effects nitrofen.
Animals↗
Postnatal pulmonary hypertension after repair of congenital diaphragmatic hernia: predicting risk and outcome.
BACKGROUND: Pulmonary hypertension (PH) after congenital diaphragmatic hernia (CDH) repair remains a significant cause of morbidity and mortality. Although treatment advances have improved overall survival, a new cohort of patients is surviving with PH beyond the postnatal period. Because the clinical entity of postnatal persistent pulmonary hypertension (PPHTN) in CDH patients has not been published, the authors undertook a retrospective study of our neonatal CDH experience to characterize this group of infants. METHODS: Charts of all infants with CDH treated at this institution from January 1991 to June 1997 were reviewed (n = 51). Persistent pulmonary hypertension by echocardiographic (Echo) measurements at the time of discharge identified PPHTN patients. Control survivors had normal pulmonary artery pressures at discharge. Physiological parameters and the results of therapeutic interventions were analyzed to predict PPHTN. RESULTS: Seven infants (four boys, three girls) had PPHTN at discharge. Significant differences with the control group were noted in length of stay, duration of intubation, and duration of nitric oxide therapy. Extracorporeal membrane oxygenation (ECMO) duration was not significantly different between the groups. By 12 months of age, PPHTN resolved in six patients (87%), and one died at 13 months. Regardless of therapy, two parameters showed 100% positive predictive value for identifying patients with PPHTN (P < .001): an Echo demonstrating PH at 2 months of age or continued oxygen requirement at 3 months. Oxygen requirement at 2 months had a 67% predictive value of PPHTN. CONCLUSIONS: With current treatment strategies for CDH, infants can survive with persistent pulmonary hypertension beyond the newborn period. The long-term survival rate is excellent, and normalization of pulmonary artery pressures can be expected. PPHTN can be predicted in those infants with Echo-defined pulmonary hypertension at 2 months.
Chi-Square Distribution↗
Measuring and developing suturing technique with a virtual reality surgical simulator.
BACKGROUND: We have developed an interactive virtual reality (VR) surgical simulator for the training and assessment of suturing technique. The surgical simulator is comprised of surgical tools with force feedback, a 3-dimensional graphics visual display of the simulated surgical field, physics-based computer simulations of the tissues and tools, and software to measure and evaluate the trainee's performance. STUDY DESIGN: This study uses the simulator to measure and compare the skills of 8 experienced vascular surgeons versus 12 medical students when performing a virtual reality suturing task. Eight parameters of the suturing task were measured: total tissue damage, accuracy of needle puncture, peak tissue tearing force, time to complete the task, damage to the surface of the tissue, angular error in needle technique, total distance traveled by the tool tip, and a measure of overall error. Three test conditions (dominant hand, nondominant hand, and 3-dimensional needle guide) were tested. Statistical significance was defined as a univariate two-sided p value < or = 0.05. RESULTS: The surgeons' average performance was significantly better than the students' average performance for three of the measured parameters (total tissue damage, time to complete the task, and total distance traveled by the tool tip) for each of the test conditions. For the test condition most similar to surgery (using the dominant hand to suture) one additional parameter was also significantly different (the measure of overall error). The medical students showed improvements for 6 of the 7 parameters for which the users received feedback during the training process. The surgeons also had significant improvement for 4 of the 7 parameters. The students had a larger improvement than the surgeons for 6 of the parameters, but these differences were not statistically significant. CONCLUSIONS: Data indicate differences between surgeon and nonsurgeon performance and in improvement in performance with training. One possible explanation for the superior performance of the surgeons is that their suturing skills applied well to the simulated suturing task. Additional research is required to confirm or deny the similarity between actual and simulated surgical tasks and the relevance of virtual reality surgical simulation to surgical skill assessment and training.
Computer Simulation↗
Tactile feedback is present during minimally invasive surgery.
BACKGROUND: The applications of minimally invasive surgery (MIS) and laparoscopy are rapidly expanding. Despite this expansion, our understanding of the importance of haptic feedback during laparoscopic surgery is incomplete. Although many surgeons believe that the use of minimally invasive techniques eliminates force feedback and tactile sensation (haptics), the importance of haptics in MIS has not been fully evaluated. There is considerable interest in the development of simulators for MIS even though the importance of force feedback remains poorly understood. This study was designed to determine the ability of experienced surgeons to interpret haptic feedback with respect to texture, shape, and consistency of an object. STUDY DESIGN: A randomized, single-blinded study was designed. Twenty surgeons were presented objects in a random order, with participants blinded as to their identity. Inspection by direct palpation, conventional instruments, and laparoscopic instruments was performed on all objects. Statistic analysis of the data was performed using chi-square analysis and, when appropriate, a Fischer exact probability test. RESULTS: Direct palpation was associated with the highest accuracy for shape identification and was superior to both conventional instruments (p < 0.001) and laparoscopic instruments (p<0.001). Fine texture analysis with either a conventional instrument or a laparoscopic instrument was superior to direct palpation (p < 0.05). Finally, the three methods of analysis were comparable for consistency analysis. CONCLUSIONS: These data indicate that laparoscopic instruments do, in fact, provide surgeons with haptic feedback. Interpretation of the texture, shape, and consistency of objects can be performed. In some situations, laparoscopic instruments appear to amplify the haptic information available. Our ongoing work is directed at further defining force interactions.
Adult↗