Biomedical subjects

A B Cresswell

Publications and source records attributed to A B Cresswell.

4 recordsLinked to original sources

PubMed2006

Digestive tract schwannoma.

BACKGROUND: Digestive tract schwannomas (DTS) are rare benign mesenchymal tumours usually affecting females between 30 and 60 years old. METHODS: We retrospectively reviewed 2 cases of DTS treated at our hospital. The first case is a 38-year-old female with gastric schwannoma presenting with acute upper gastro-intestinal bleeding. The second case is a 36-year-old female with mesenteric schwannoma presenting with chronic right iliac fossa pain. Both patients underwent surgical resection of the tumour. RESULTS: Histology and immunohistochemistry revealed the typical appearance of a DTS. CONCLUSION: DTS is most commonly found in the stomach. It is usually asymptomatic but can present with variable symptoms. Definitive diagnosis can only be made on the basis of immunohistochemistry. Surgical resection is the treatment of choice.

Adult↗

PubMed2003

Real-time thermography during energized vessel sealing and dissection.

BACKGROUND: Energized dissection systems facilitate laparoscopic dissection and hemostasis and reduce instrument traffic. However, they can introduce undesirable thermal collateral/proximity damage to adjacent structures mainly by heat conduction, although other mechanisms may be involved. The latest generation devices have the potential to reduce the incidence of such problems through use of active feedback control over the power output. This effectively regulates the delivery of energy to the target tissue with minimal thermal collateral damage. In addition, innovative heat-sink engineering of the device head ensures that the surface of the instrument tip remains cool (<45 degrees C). In this study, we evaluated the performance of this technology (LigaSure) by using dynamic infrared thermography. The thermal imaging measurements were then correlated with histopathologic studies. The overall value of in situ thermography as an adjunct to energized surgical dissection systems was also assessed. METHODS: Eight anesthetized pigs underwent open surgery to mobilize eight target vessels/organs in a randomized fashion. The LigaSure vessel sealing system with Instant Response Technology was used with three different interchangeable heads. In situ dynamic thermography was undertaken with a thermal imaging camera operating in the mid-infrared (3-5 microm) waveband and with each fully digitized 12-bit thermographic frame acquired at a rate of 60 Hz. Following sacrifice at the end of the dissection, tissue from the dissected regions was harvested for histology by an independent pathologist who was blinded to the thermographic data. RESULTS: Seals made with both the LS1000 5-mm laparoscopic head (predominantly to the small bowel and colon) and the LS1100 10-mm (Atlas) device (on the liver and short gastric tissues) were outwardly satisfactory. The average thermal spread [see text] with the LS1000 was = [see text] 4.4 mm, and the exposed surface of the instrument tip developed a temperature of approximately 100 degrees C. This instrument thus has the potential, albeit small, for heat-related proximity iatrogenic injury. The more technologically advanced LS1100 10-mm laparoscopic instrument exhibited a superior performance, with [see text] = 1.8 mm, and with a maximal temperature on the exposed surface of the jaws well within tolerable limits (approximately 35 degrees C) for use during surgery (laparoscopic or open). This was confirmed by histological studies that demonstrated negligible evidence of thermal damage. CONCLUSIONS: In situ thermal imaging represents a powerful modality for the monitoring of energized dissection/coagulation during surgery. The LigaSure system used with the LS1100 head constitutes a very safe option for energized dissection and hemostasis of vessels with a diameter of up to approximately 7 mm.

Animals↗

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↗

PubMed1999

Methods for improving performance under reverse alignment conditions during endoscopic surgery.

BACKGROUND: There are times during endoscopic procedures when the surgeon has to operate ahead of the camera/telescope assembly. As a result, the image displayed on the monitor will be an inverted mirror image of the operative field (reverse alignment). The present study addresses the extent of these difficulties and suggests some techniques that may be used to overcome the problem. METHODS: Eight specialist registrars participated in experiments involving the execution of a simulated dissection task under 12 different imaging conditions. These conditions included normal alignment, reverse alignment, total or partial digital correction of reverse alignment (about the horizontal and vertical axes independently and together), and a simple rotation of the camera through 180 degrees. Normal, reverse, and corrected reverse alignment were also tested with optical axes of 45 degrees and 60 degrees. The endpoints were the task execution and the errors rate. RESULTS: A marked deterioration in execution time was observed when the surgeons worked under reverse alignment rather than under normal viewing (p = 0.036). Significant improvement in execution-time errors rate was found when both the horizontal and vertical axes were digitally corrected simultaneously (p = 0.27) and when the camera was rotated 180 degrees with respect to the telescope during reverse alignment (p = 0.28). CONCLUSIONS: The effect on performance produced by reverse alignment of the endoscope and instruments can be overcome by means of digital electronic processing, or simply by turning the camera through 180 degrees.

Adult↗