Face, content and construct validity of the University of Washington virtual reality transurethral prostate resection trainer.

PURPOSE: We examined the face, content and construct validity of version 1.0 of the University of Washington transurethral prostate resection (TURP) trainer. MATERIALS AND METHODS: Version 1.0 of a virtual reality based simulator for transurethral skills was developed at our laboratory by integrating TURP hardware with our virtual 3-dimensional anatomy, irrigation control, cutting, bleeding and haptics force feedback. A total of 72 board certified urologists and 19 novices completed a pre-task questionnaire, viewed an introductory training video and performed a pre-compiled 5-minute resection task. The simulator logged operative errors, gm resected, blood loss, irrigant volume, foot pedal use and differential time spent with orientation, cutting or coagulation. Trainees and experts evaluated the simulator on a modified likert scale. The 2-tailed Levene t test was used to compare means between experts and novices. RESULTS: Overall version 1.0 content was between slightly and moderately acceptable. Experts spent less time with orientation (p < 0.0001), resected more total tissue (p < 0.0001), had more gm resected per cut (p = 0.002) and less blood loss per gm resected (p = 0.032), used less irrigant per gm resected (p = 0.02) and performed fewer errors (p < 0.0001) than novices. CONCLUSIONS: We established the face, content and construct validity for version 1.0 of the University of Washington TURP trainer to simulate the skills necessary to perform TURP. A predictive validity study showing a translation of skills from the virtual environment to the operating room will complete the validation of this model.

The representation of blood flow in endourologic surgical simulations.

An image-based approach has been developed to represent bleeding in a simulator for transurethral resection of prostate (TURP). While previous attempts have simulated bleeding over tissue surfaces or in blood vessels, our approach focused on the macroscopic visualization of bleeding in a fluid environment. TURP is an ideal procedure for simulation-based training because of the dynamic environment and the variety of flow patterns it presents. The first step in the development of the simulator was the generation of blood flow movies which consisted of capturing videos of bleeding vessels in vitro, processing them to separate the actual blood from the background anatomy and organizing the movies into a parametric database. During the running of the simulation, resection of prostate tissue systematically triggers bleeding events and the playback of a blood flow movie. The blood flow movie is texture mapped onto a virtual surface that is positioned oriented, morphed, composited and looped into the virtual scene.

Issues in validation of a dermatologic surgery simulator.

At the University of Washington, we have been developing a suturing simulator using novel finite element model techniques which allow real-time haptic feedback. The issues involved in measuring validity in a suturing model have not been examined in a systematic way. Very few studies exist on the surgical factors that lead to good sutures. We have examined published data on these factors as well as previously studied metrics in suture training. This information has been combined with a review of types of validity (e.g., face, construct, predictive and concurrent) and reliability that must be considered in assessing any surgical simulator.

Laparoscopic surgical simulator and port placement study.

We have developed a virtual laparoscopic surgical simulator and gathered data during student trial runs. The students performed simulated surgical dissections from 3 pairs of port positions with angles between the cutting and grasping instruments set to 60, 90, and 120 degrees. Preliminary data indicates improved performance at the 90 degree angle. Study updates can be found at http:¿www.hitl.washington.edu/research/lss

Creating fast finite element models from medical images.

The procedure for creating a patient-specific virtual tissue model with finite element (FE) based haptic (force) feedback varies substantially from that which is required for generating a typical volumetric model. In addition to extracting geometrical and texture map data to provide visual realism, it is necessary to obtain information for supporting a FE model. Among many differences, FE-based VR environments require a FE model with appropriate material properties assigned. The FE equation must also be processed in a manner specific to the surgical task in order to maximize deformation and haptic computation speed. We are currently developing methodologies and support software for creating patient-specific models from medical images. The steps for creating such a model are as follows: 1) obtain medical images and texture maps of tissue structures; 2) extract tissue structure contours; 3) generate a 3D mesh from the tissue structure contours; 4) alter mesh based on simulation objectives; 5) assign material properties, boundary nodes and texture maps; 6) generate a fast (or real-time) FE model; and 7) support the tissue models with task-specific tools and training aids. This paper will elaborate on the above steps with particular reference to the creation of suturing simulation software, which will also be described.

Validation of the Madigan ESS simulator.

The Madigan Endoscopic Sinus Surgery (ESS) Simulator, developed by a multi-institution team led by Lockheed Martin, includes force-feedback instrument and virtual endoscope interaction with three-dimensional paranasal anatomy models derived from the Visible Human dataset, supplemented by a variety of graphical and auditory instructional aids embedded in the model. Our formal evaluation of Version 1.2 of the system focused on its validity as an ESS simulator. Run-time and survey data were collected for three groups of subjects on a common protocol progressing through the three basic ESS subtasks: navigation, injection, and dissection. Non-MD subjects performed the tasks on a simplified abstract virtual model with instructional aids (hoops for the navigation path, injection targets, dissection spheres, auditory feedback about task completion, and simulated patient heart rhythm). Non-ENT MDs progressed from this "novice" model to a simulated anterior ethmoidectomy on an "intermediate" model with the aids embedded in the reconstructed and segmented paranasal anatomy. Otolaryngologists ranging from second-year ENT residents through senior staff progressed through both the abstract and intermediate models, and then performed the simulated surgical procedure on an "advanced" model, consisting of the anatomy with no instructional aids. The procedural validity of the simulator is supported by a strong correlation between performance on the simulator and degree of prior ESS experience, by convergent correlation among independent measures of subject task performance, and by subjective evaluations by experienced ESS surgeons.

New interface metaphors for complex information space visualization: an ECG monitor object prototype.

Wearable augmented reality medical (WARM) interfaces could provide ubiquitous point-of-care decision support and enhance the quality and efficiency of clinicians' efforts. Creation of such systems involves the design and evaluation of new information displays that leverage the representational and presentational capabilities of three-dimensional AR environments. We describe our first efforts in this process: the implementation of interface objects for display of real-time electrocardiographic monitoring information and an evaluation methodology using a simulated clinical environment. Our pilot data confirm the utility of presentation modes that place simultaneous information tasks in close proximity, and highlight issues encountered in designing new representations of medical information.

ENT endoscopic surgical training simulator.

This paper describes work in progress on the design and development of a prototype simulator for minimally invasive otolaryngology surgical training. The anatomy of the paranasal sinuses is geometrically complex and dangerously close to the brain and orbits, making this procedure challenging to practice and difficult to learn. We discuss the potential role of computer simulation to enhance and accelerate acquisition of surgical skills. The design goals of the prototype include high-fidelity simulation of the endoscopic imagery and haptic cues of surgical palpation. The prototype enables endoscopic navigation and limited interactive tissue manipulation and dissection tasks on a virtual patient using realistic replicas of surgical tools. We present an overview of the system architecture with a discussion of the technological challenges, design issues and current status of the efforts.

The expert surgical assistant. An intelligent virtual environment with multimodal input.

Virtual Reality has made computer interfaces more intuitive but not more intelligent. This paper shows how an expert system can be coupled with multimodal input in a virtual environment to provide an intelligent simulation tool or surgical assistant. This is accomplished in three steps. First, voice and gestural input is interpreted and represented in a common semantic form. Second, a rule-based expert system is used to infer context and user actions from this semantic representation. Finally, the inferred user actions are matched against steps in a surgical procedure to monitor the user's progress and provide automatic feedback. In addition, the system can respond immediately to multimodal commands for navigational assistance and/or identification of critical anatomical structures. To show how these methods are used we present a prototype sinus surgery interface. The approach described here may easily be extended to a wide variety of medical and non-medical training applications by making simple changes to the expert system database and virtual environment models. Successful implementation of an expert system in both simulated and real surgery has enormous potential for the surgeon both in training and clinical practice.

Cost comparison of different methods of screening for cystic fibrosis.

OBJECTIVE: To compare the costs of several proposed methods of screening for cystic fibrosis. SETTING: England and Wales. METHODS: The costs of screening carried out at hospital antenatal clinics, general practitioner (GP) antenatal consultations, GP surgeries, and at work were estimated using data from demonstration projects. Couple screening, stepwise screening, and screening of individuals were considered. RESULTS: Couple screening at antenatal hospital clinics was the least expensive per carrier couple detected, amounting to 35,700 pounds (142,900 pounds for each potential cystic fibrosis fetus detected). The costs of the reagents (25 pounds per test) accounted for over 60% of this total. CONCLUSIONS: Antenatal screening, in addition to being the most cost effective method of screening, is also medically the screening method of choice as it provides information at the latest time when effective preventive action can be taken and at a time when all people to be screened are likely to be accessible. If the costs of the reagents could be reduced to 5 pounds (still higher than the costs of most diagnostic reagents) the cost for each pregnant carrier couple offered screening would be reduced by 50% to about 18,000 pounds, and the cost of offering screening to 684,000 pregnant couples in England and Wales would be about 9 1/2 m instead of 19 m pounds.

[Kidney retransplantation: prognostic factors in a series of 84 cases]. / La retransplantation rénale (RT): facteurs pronostiques dans une série de 84 cas.

Results are presented of a series of 84 patients receiving renal retransplants over the last 12 years. One year survival rate of patients and transplants was 87.6% and 79.1% respectively, compared with 92.5% and 81.2% for the 783 first grafts performed during the same period. Positive prognostic features were the absence of sensitization, survival of the first transplant for more than 6 months, and the inclusion of cyclosporin in the immunodepressive treatment.

Drug information skills for pharmacy students: curriculum integration.

For pharmacy students to provide optimal and complete pharmaceutical care, it is vital that they develop drug information skills. At the University of Southern California, the School of Pharmacy and the Norris Medical Library have established an interactive educational program. Library programs support an increasingly complex progression of information retrieval, evaluation, organization, application, and communication. Librarians are systematically involved in all four years of coursework for the doctor of pharmacy degree. Training and experience in computer literacy and online database searching are included in the library components. Description of the educational program covers its beginning a decade ago, current status, and future in an environment of rapidly advancing technology.

Release of corrosion products by F-75 cobalt base alloy in the rat. III: Effects of a carbon surface coating.

A pyrolytic carbon coating was applied to F-75 chromium-cobalt-molybdenum alloy in an effort to reduce the release of corrosion products in vivo. After intramuscular implantation in the rat, a complex pattern of serum and urine concentration elevations of chromium, cobalt, and nickel was seen. The carbon-coated implants released more chromium and cobalt than uncoated controls, as seen by significantly elevated metal concentrations in serum and urine. Animals receiving carbon-coated implants showed a high rate of recurrent implant site inflammation. Neoplastic infiltration of 24 animals with coated implants, but not in any of the 16 animals which received either uncoated F-75 microsphere or poly(ethylene) particulate implants.

Changing prescribing practices through individual continuing education.

In a study involving 94 practicing physicians, committees of clinical pharmacologists analyzed copies of prescriptions (and additional relevant clinical data) to identify problems in prescribing ("educational needs"). Only the ten most commonly prescribed drugs were studied in the samples of 200 prescriptions from each physician; 1061 problems were identified in the prescriptions of the 94 participants. One physician group (n = 41) received feedback (instructional packets) addressing specific problems in prescribing; a second sample consisting of 200 prescriptions was then collected and analyzed. The physicians in this group changed their prescribing practices 30% of the time in accordance with recommendations, whereas those in the group that received no educational feedback changed in only 3% of the cases. When a physician stated an intention to change, an actual change resulted 50% of the time. Individualized teaching in response to real events in practice is a practical and effective method of improving physician performance.

New clinical roles for pharmacists: a study of role expansion.

This study assessed the legitimacy of expanded roles for pharmacists with different status audiences. Pharmacy is a profession in transition and is characterized by considerable ambiguity and uncertainty concerning its status as a health care profession. Significant changes have occurred within the profession of pharmacy in the past few decades which have led to loss of function, social power and status. The response of the profession has been a movement toward a patient-oriented, clinical role for pharmacists. Hypotheses concerning level of support for expanded roles were derived from two conflict-based models of professionalization: a power model which focuses on conflict between professions and the central role of power in defining occupational territory; and a process model which focuses on conflict of interest and diversity within a profession and the development of 'segments' which struggle for control of a profession's direction. Data were collected by self-administered questionnaires sent to California pharmacists, physicians and nurses. Respondents were asked to indicate level of support for 20 role activities for pharmacists working in two practice settings (community and hospital). Pharmacy faculty were the most supportive of the clinical role activities, followed by practicing pharmacists, nurses and physicians. Physicians and nurses were more antagonistic toward clinical activities in the community than hospital practice setting, and were most antagonistic toward role activities which require independent judgement or autonomous action relevant to patient care on the part of the pharmacist. Differences were also noted in support for clinical role activities within the pharmacists' group. The effect of experience in working with a clinical pharmacist on support for clinical role activities is also discussed.

Assessing whether a clinical pharmacy program is meeting its goals.

An assessment of whether the clinical pharmacy program at Memorial Hospital Medical Center (MHMC), Long Beach CA, was meeting its goals is presented. MHMC is a 858-bed, nonprofit teaching hospital that initiated a clinical pharmacy program in 1967. The program's three foremost goals were to: (1) establish cohesive and standardized clinical services, (2) promote the acceptance of the roles and functions of clinical pharmacists by physicians and nurses, and (3) assure the provision of good quality care. The evaluation data were collected over a six-week period using questionnaire surveys of approximately 28 pharmacists, 146 physicians, and 389 nurses; pharmacist service reports from 5991 drug monitorings; 228 medical record audits for six drugs; 68 guideline compliance records for three drugs; interviews with 131 users of the drug information services; abd logs of 3946 pharmacist encounters with other health-care providers. Generally, the clinical pharmacy program was found to be meeting its goals. Most of the monitorings (81.6%) were initiated by pharmacists, and 20% resulted in changes in drug therapy. The pharmacists adhered to the pharmacy department's monitoring and dosing guidelines. There was unanimous satisfaction among users of the drug information service with the response received from pharmacists, and 99% satisfaction with the promptness of response and accuracy of the information. Sixty-eight percent of the pharmacists reported discussing general issues with physicians, and 72% answered patient-specific questions from physicians. The physicians (96%) and nurses (97%) thought that there was an improvement in the quality of patient care as a result of pharmacist involvement. Pharmacists at MHMC are providing useful clinical services.