Biomedical subjects

F J Carter

Publications and source records attributed to F J Carter.

5 recordsLinked to original sources

PubMed2005

Consensus guidelines for validation of virtual reality surgical simulators.

The Work Group for Evaluation and Implementation of Simulators and Skills Training Programmes is a newly formed sub-group of the European Association of Endoscopic Surgeons (EAES). This work group undertook a review of validation evidence for surgical simulators and the resulting consensus is presented in this article. Using clinical guidelines criteria, the evidence for validation for six different simulators was rated and subsequently translated to a level of recommendation for each system. The simulators could be divided into two basic types; systems for laparoscopic general surgery and flexible gastrointestinal endoscopy. Selection of simulators for inclusion in this consensus was based on their availability and relatively widespread usage as of July 2004. Whilst level 2 recommendations were achieved for a few systems, it was clear that there was an overall lack of published validation studies with rigorous experimental methodology. Since the consensus meeting, there have been a number of new articles, system upgrades and new devices available. The work group intends to update these consensus guidelines on a regular basis, with the resulting article available on the EAES website (http://www.eaes-eur.org ).

Computer Simulation↗

PubMed2001

The performance of master surgeons on standard aptitude testing.

BACKGROUND: Identification of the desired psychomotor abilities of optimal surgical performance, if possible, would be useful in the selection of surgical trainees. The aim of this study was to determine the level of these abilities among endoscopic consultant surgeons held in high regard by their peers. METHODS: Twenty endoscopic consultant "master" surgeons were tested on three aptitude tests: the Gibson Spiral Maze Test (error score measures eye-hand coordination), the Crawford Small Parts Dexterity Test (execution time indicates manual dexterity), and the Space Relations Test (correct scores reflect visuo-spatial ability). Their performance was compared with that of 20 medical students and the reference norm as provided by the tests' manuals. RESULTS: The median scores of master surgeons fell in the 20th, 24th, and 30th percentiles, whereas the scores of medical students fell in the 50th, 20th, and 65th percentile of norm reference for the Gibson Spiral Maze, Crawford Small Parts Dexterity, and Space Relations tests, respectively. The master surgeons enacted significantly fewer errors (Gibson Spiral Maze), had similar execution times (Crawford Small Parts Dexterity), and lower visuo-spatial scores (Space Relations) than medical students. CONCLUSION: The level of eye-hand coordination and manual dexterity of master surgeons was found to be higher than that of the average norm including medical students, while their visuo-spatial ability was lower.

Aptitude Tests↗

PubMed2001

Measurements and modelling of the compliance of human and porcine organs.

Stress-strain data obtained from animal and human tissue have several applications including medical diagnosis, assisting in surgical instrument design and the production of realistic computer-based simulators for training in minimal access surgery. Such data may also be useful for corroborating mathematical models of tissue response. This paper presents data obtained from ex-vivo and in-vivo tissue indentation tests using a small indentor that is similar to instruments used in minimal access surgery. In addition, uniform stress tests provide basic material property data, via an exponential stress-strain law, to allow a finite element method to be used to predict the response for the non-uniform stresses produced by the small indentor. Data are obtained from harvested pig liver and spleen using a static compliance probe. Data for human liver are obtained from volunteer patients, undergoing minor open surgery, using a sterile hand-held compliance probe. All the results demonstrate highly non-linear stress-strain behaviour. Pig spleen is shown to be much more compliant than pig liver with mean elastic moduli of 0.11 and 4.0 MPa respectively. The right lobe of human liver had a mean elastic modulus of about 0.27 MPa. However, a single case of a diseased liver had a mean modulus of 0.74 MPa--nearly three times the stiffness. It was found that an exponential stress-strain law could accurately fit uniform stress test data and that subsequent finite element modelling for non-uniform stress around a small indentor matched measured force characteristics.

Animals↗

PubMed2000

Puncture forces of solid organ surfaces.

BACKGROUND: In this experimental study, we measured the force needed to puncture the liver (low elastin) and the spleen (high elastin). The surface displacement preceding puncture was also measured. These data are relevant to an understanding of surgical technique and are essential to the development of electronic surgical simulators. METHODS: Controlled puncture experiments were performed on intact organs harvested from pigs and sheep, as well as on their surface capsules following removal and suspension at zero strain and at three increasing levels of prestrain. The biomechanical data were compared with information obtained from histological studies. RESULTS: The spleen has a higher puncture force than the liver and suffers greater displacement before puncture (p < 0.05). Prestrain decreases displacement before puncture (p < 0.05) but has no effect on puncture force. CONCLUSION: The higher puncture force and displacement of spleen, as compared with liver, is probably due to its higher elastin content.

Animals↗

PubMed2000

Efficacy and safety of lesopitron in outpatients with generalized anxiety disorder.

OBJECTIVE: To compare the relative efficacy and safety of lesopitron 4-80 mg/d versus lorazepam 2-4 mg/d and placebo in a subgroup of patients with anxiety history taken from a larger study of patients with a primary diagnosis of generalized anxiety disorder (GAD). DESIGN: Six-week, randomized, double-blind, parallel, placebo and lorazepam-controlled, Phase II, single-center, outpatient study. SETTING: Outpatient clinic. PATIENTS: One hundred sixty-one patients with GAD were randomized in the main study; 68 with a documented history of GAD or anxiety disorder not otherwise specified were included in the subgroup. METHODS: After a one-week placebo lead-in, patients were randomized to receive placebo, lesopitron, or lorazepam twice daily for six weeks, followed by a one-week taper period. Efficacy was assessed using the Hamilton Rating Scale for Anxiety (HAM-A) and the Clinical Global Impressions scale. Safety was assessed through physical examinations, monitoring of vital signs, 12-lead electrocardiograms, laboratory analyses, and adverse event monitoring. RESULTS: An overall mean improvement in the HAM-A total score between baseline and end point for all three treatment groups was seen, with mean changes of 3.4 (95% CI 2.0 to 4.8), 6.1 (95% CI 4.1 to 8.1), and 6.1 (95% CI 4.6 to 7.6) for the placebo, lesopitron, and lorazepam groups, respectively (omnibus p = 0.044, uncorrected). Positive treatment effects were also observed in the subgroup population on several other measures and suggest that additional therapeutic trials may be warranted. Future trials could be stratified on the basis of referral status (symptomatic volunteer vs. clinical patient with preexisting illness) or previous exposure to anxiolytics, and use a fixed-dose rather than flexible-fixed-dose design. CONCLUSIONS: The subgroup analysis represents a comparison of treatment outcome in GAD patients presenting with a history of previous episodes of GAD or anxiety disorder not otherwise specified compared with those who were experiencing their first episode of GAD and reported no anxiety history. Although the overall study analysis was equivocal, for the approximately 40% of patients with recurrent anxiety disorder, beneficial effects for both lesopitron and lorazepam are suggested.

Adult↗