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Biomedical subjects

G B Hanna

Publications and source records attributed to G B Hanna.

At least 19 recordsLinked to original sources
PubMed2000

Effect of intracorporeal-extracorporeal instrument length ratio on endoscopic task performance and surgeon movements.

HYPOTHESIS: Better endoscopic task performance and more ergonomic movements of a surgeon's dominant upper limb can be achieved within a certain range of intracorporeal-extracorporeal instrument length ratio. DESIGN: Investigating the effect of 3 intracorporeal-extracorporeal instrument length ratios (240:120 mm, level 1; 180:180 mm, level 2; and 120:240 mm, level 3) on efficiency and quality of a standardized endoscopic task (intracorporeal surgeon's knot). Ten surgeons tied 360 knots inside a trainer in a random sequence. Task efficiency was measured by the execution time, which was recorded for each knot. Task quality was measured by the knot quality score, derived from the force-extension curves obtained by distraction of each knot in a tensiometer. Motion analysis parameters were obtained at the elbow and shoulder joints using a 3-dimensional motion analysis system (Kinemetrix Model 5.0-3D/3MBM; Medical Research Ltd, Leeds, England). The Kruskal-Wallis and Mann-Whitney tests were used for analysis. RESULTS: The level 3 ratio had the lowest knot quality score (P = .07) and longest execution time (P<.05). The range of movement at the elbow was significantly greater with the level 3 ratio than with the level 1 ratio (P<.05). The level 3 ratio also resulted in the widest range of movement at the shoulder (P<.05 for level 2 vs 3; P = .06 for level 1 vs 3). The median angular velocity was 329.5 degrees/s, 360 degrees/s, and 530 degrees/s for levels 1, 2, and 3, respectively (P = .10). CONCLUSIONS: Intracorporeal-extracorporeal instrument length ratio below 1.0 degrades task performance and is associated with a wider range of movement at the elbow and shoulder and a higher angular velocity at the shoulder.

Biomechanical Phenomena↗
PubMed2000

Influence of two-dimensional and three-dimensional imaging on endoscopic bowel suturing.

Several three-dimensional (3-D) video-endoscopic systems have been introduced in surgical practice to enhance depth perception during minimal access surgery (MAS), but the facilitation of endoscopic manipulations by the current 3-D systems remains unproved. The aim of the study was to investigate the influence of 2-D and 3-D imaging modalities on intracorporeal suturing. The standard task consisted of suture closure of 60 mm enterotomies made in porcine small bowel with continuous seromuscular 3/0 Polysorb. Ten experienced surgeons participated in the study. The imaging systems were Storz (2-D), Welch Allyn (3-D), and Zeiss (as both 2-D and 3-D). Each surgeon performed two tasks with each modality in a random sequence. The outcome measures were execution time, suture line leakage pressure, and suture placement score. In addition, the participating surgeons assigned subjective scores on the image quality and the adverse effects of the imaging systems. There was no significant difference in the execution time, leakage pressure, and suture placement score among the various imaging modalities. Depth perception was rated as similar with 2-D and 3-D imaging. Surgeons experienced visual strain with the three systems, but it was rated higher with 3-D imaging. With the current technology, we have not documented any significant difference in task efficiency and quality of endoscopic bowel suturing by trained surgeons between 2-D and 3-D imaging systems.

Analysis of Variance↗
PubMed2000

Differences between experts and trainees in the motion pattern of the dominant upper limb during intracorporeal endoscopic knotting.

BACKGROUND: Very little research has been carried out on the ergonomics of surgeon-instrument interface. The aim of this study is to investigate the effect of experience on the motion pattern of the dominant upper limb during endoscopic intracorporeal knot tying. METHODS: Two groups of 5 surgeons (expert consultants and higher surgical trainees) tied 360 surgeon's knots inside an endoscopic trainer in a random sequence. Motion analysis at the elbow and shoulder joints of the dominant upper limb was carried out using 3-dimensional kinemetrix system. Each knot was distracted using a tensiometer. The endpoints were the execution time, knot quality score, angular velocity and range of movement. Kruskal-Wallis one-way analysis of variance and Mann-Whitney U test were used for analysis. RESULTS: The expert group had a better knot quality score (p < 0.005) and shorter execution time (p < 0.0001) than beginners. Motion analysis at the shoulder joint showed that experts had a higher angular velocity (p < 0.05) and a wider range of movement with more adduction (p < 0.01) compared to beginners. No significant differences were found at the elbow. CONCLUSION: The better task performance by expert surgeons is associated with controlled rapid manipulations and a wider range of movement at the shoulder joint of the dominant upper limb.

Adult↗
PubMed1999

Influence of the optical axis-to-target view angle on endoscopic task performance.

BACKGROUND: The location of the optical port and the choice of endoscope determine the angle subtended between the optical axis of the endoscope and the plane of the operation target: the optical axis-to-target view (OATV) angle. The aim of the study was to investigate the influence OATV angle on endoscopic task performance. METHODS: The Dundee Endoscopic Psychomotor Tester was used for objective assessment of endoscopic task performance. Ten surgeons carried out a standard task with the optical axis of the endoscope subtending 90 degrees, 75 degrees, 60 degrees and 45 degrees to the target surface. Each subject underwent three test sessions. Each session consisted of one run with each of the OATV angles in a random order. The outcome measures were the errors rate, the execution time, and the force applied on the target. RESULTS: The 90 degrees OATV angle had the best accuracy, the shortest execution time, and the lowest force applied on the back plate. The errors rate increased from 17% with the 90 degrees OATV angle to 79% with the 45 degrees angle. There was a significant increase in execution time and force with the decrease in the OATV angle (p < 0.0001). CONCLUSIONS: The best task performance is obtained when the optical axis of the endoscope is perpendicular to the target plane.

Analysis of Variance↗
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↗
PubMed1999

Rocker handle for endoscopic needle drivers. Technical and ergonomic evaluation by infrared motion analysis system.

BACKGROUND: The design of the handle on instruments for endoscopic surgery determines comfort and efficiency of use by the surgeon. This applies particularly to needle drivers. METHODS: A novel rocker handle was designed to provide holding comfort and intuitive function. This rocker handle was compared with a finger-loop handle in a study involving 10 surgeons who tied a total of 360 intracorporeal surgeons' knots in a random sequence. The end points in this study were the execution time, knot quality, and motion analysis parameters of the surgeon's elbow and shoulder joints. RESULTS: Intracorporeal surgeon's knots tied with the rocker-handle driver exhibited a better knot quality, although this was not significant (p = 0.097). A significant improvement in the knot quality score (KQS) was observed between the first and the second sessions (p = 0.045) with the rocker handle, whereas no significant learning effect was observed for the finger-loop handle. During intracorporeal knot tying, the angular velocity at the elbow and shoulder joints was consistently lower with the rocker handle, suggesting that more controlled movements are enacted by the surgeon with this handle. Discomfort from finger-loop pressure on the thumb was reported by 3 of 10 surgeons with the finger-loop handle, whereas no discomfort was reported for the rocker handle. CONCLUSIONS: The new rocker handle improves the quality of task performance by eliminating discomfort and reducing angular velocities at the shoulder and elbow joints during use.

Endoscopes↗
PubMed1999

E.A.E.S. multicenter prospective randomized trial comparing two-stage vs single-stage management of patients with gallstone disease and ductal calculi.

BACKGROUND: The current management of patients with gallstone disease and ductal calculi consists of endoscopic stone extraction (ESE) followed by laparoscopic cholecystectomy (LC). Following the advent of techniques of laparoscopic ductal stone clearance, an alternative single-stage laparoscopic treatment was introduced for these patients. The European Association of Endoscopic Surgery (E.A. E.S.) set up a ductal stone trial to compare the relative efficacy and outcome of these two management options. METHODS: A prospective randomized controlled clinical trial compared two management options. Group A (n = 150) received preoperative endoscopic retrograde cholangiography (ERC) with ESE followed by LC during the same hospital admission, and group B (n = 150) received single-stage laparoscopic management. RESULTS: There were no significant differences between the two groups in the clinical demographic details and the pretreatment biochemical findings. In group A, 14 of 150 patients received single-stage treatment; in group B, 17 of 150 were managed by the two-stage approach (protocol violation = 31/300, 10%). In group A patients managed in accordance with randomization, ERC was successful in 129/136 (95%) and preoperative ESE succeeded in 82/98 (84%) with ductal calculi detected by the ERC. Two patients had malignancies and one refused surgery. Thus, 133 patients underwent surgery. Of this group, 116 had LC only and 17 had LC and attempted laparoscopic duct exploration. There were eight conversions to open surgery (6%), 17 complications for both stages (12.8%), and two postoperative deaths (1.5%). In group B patients managed in accordance with randomization, intraoperative cholangiography was successful in 132/133 (99%). Twenty-one (16%) had normal findings, ductal calculi were found in 109, and other pathology was noted in two (periampullary cancer, severe pancreatitis). These two patients and one other (who had gross adhesion in the triangle of Calot) were converted at the start of the procedure. Transcystic ductal stone clearance was successful in 45 of 56 patients (80%), and laparoscopic direct common duct (CBD) exploration was successful in 47 of 55 patients (85%). This group includes 53 patients who underwent primary direct exploration and two failed attempts at transcystic extraction. The conversion rate was 13%. Postoperative complications were encountered in 21 patients (15.8%), and one patient died of a major myocardial infarction (0. 75%). The one postoperative death and the 10/11 biliary complications occurred in the laparoscopic supraduodenal CBD exploration subgroup. The conversion rate was higher in group B (17 vs eight; p = 0.08). Laparotomy in the postoperative period was required in three patients in group A and four patients in group B. The group B patients were in hospital for 3 days less than patients who had two-stage management (median, 6.0, IQR = 4.25-12 vs median, 9.0, IQR = 5.5-14; p < 0.05). CONCLUSIONS: The results demonstrate equivalent success rates and patient morbidity for the two management options but a significantly shorter hospital stay with the single-stage laparoscopic treatment. The findings indicate that in fit patients (ASA I and II), single-stage laparoscopic treatment is the better option, and preoperative ESE should be confined to poor-risk patients-i.e., those with cholangitis or severe pancreatitis.

Adolescent↗
PubMed1998

Randomised study of influence of two-dimensional versus three-dimensional imaging on performance of laparoscopic cholecystectomy.

BACKGROUND: Several three-dimensional video-endoscopic systems have been introduced to enhance depth perception during minimum-access surgery. However, there is no conclusive evidence of benefit, and these systems are more expensive than conventional two-dimensional systems. We undertook a prospective randomised comparison of two-dimensional and three-dimensional imaging in elective laparoscopic cholecystectomy for symptomatic gallstone disease. METHODS: The operations were done by four specialist registrars as part of their higher surgical training. 60 operations were randomised for execution by either two-dimensional or three-dimensional imaging display (30 by each method). The degree of difficulty of the operation was graded by a consultant surgeon on a standard grading system. The primary endpoints were execution time and the errors made during the procedure. The secondary endpoints were subjective assessment of the image quality and adverse effects on the surgeon. FINDINGS: There was no difference between the two-dimensional and three-dimensional display groups in median execution time (3160 [IQR 2735-4335 vs 3100 [2379-3710] s; p = 0.2) or error rate (six vs six). Surgeons reported adverse symptoms immediately after the operations with both systems. The scores for visual strain, headache, and facial discomfort were higher with the three-dimensional system. INTERPRETATION: With the current technology, three-dimensional systems based on sequential imaging show no advantage over two-dimensional systems in the conduct of laparoscopic cholecystectomy.

Adult↗
PubMed1998

Appendiceal tumors: retrospective clinicopathologic analysis of appendiceal tumors from 7,970 appendectomies.

BACKGROUND: Appendiceal tumors are rare and often unexpectedly discovered in an acute situation, in which decision-making is difficult. To help define the most appropriate management, a retrospective analysis was undertaken to describe the clinicopathologic behavior of appendiceal tumors, and the literature was reviewed of the management of the different types of appendiceal tumors. METHOD: From a single center, a histopathologic database of 7,970 appendectomies, all appendiceal tumors, were identified and case notes reviewed. Analysis of clinical presentation, histopathology, operation, and outcome is presented. RESULTS: During a 16-year period (7,970 appendectomies), 74 patients (0.9 percent) with appendiceal tumors were identified: 42 carcinoid, 12 benign, and 20 malignant. Acute appendicitis was the most common presentation (49 percent), and 9.5 percent were incidental findings. Primary malignant tumors of the appendix were found in 0.1 percent of all appendectomies. Secondary malignant disease was identified in the appendix of 11 patients, most commonly (55 percent) from patients with primary colorectal disease. There was a high incidence of synchronous and metachronous colorectal cancer in all appendiceal tumors: carcinoids, 10 percent; benign tumors, 33 percent; secondary malignancies, 55 percent; primary malignancies, 89 percent. CONCLUSION: Appendiceal tumors are uncommon and most often present as appendicitis. Most are benign and can be managed by appendectomy, except adenocarcinomas and carcinoids larger than 2 cm, which are most appropriately managed by right hemicolectomy. A suggested management algorithm is provided. Controversy exists over the management of carcinoids 1 to 2 cm in size and adenocarcinoids. All types of appendiceal tumors have a high incidence of synchronous and metachronous colorectal cancer.

Adenocarcinoma↗
PubMed1998

Total radiated power, infrared output, and heat generation by cold light sources at the distal end of endoscopes and fiber optic bundle of light cables.

BACKGROUND: Skin burns and ignition of drapes have been reported with the use of cold light sources. The aim of the study was to document the temperature generated by cold light sources and to correlate this with the total radiated power and infrared output. METHODS: The temperature, total radiated power, and infrared output were measured as a function of time at the end of the endoscope (which is inserted into the operative field) and the end of the fiber optic bundle of the light cable (which connects the cable to the light port of the endoscope) using halogen and xenon light sources. RESULTS: The highest temperature recorded at the end of the endoscope was 95 degrees C. The temperature measured at the optical fiber location of the endoscope was higher than at its lens surface (p < 0.0001). At the end of the fiber optic bundle of light cables, the temperature reached 225 degrees C within 15 s. The temperature recorded at the optical fiber location of all endoscopes and light cables studied rose significantly over a period of 10 min to reach its maximum (p <0.0001) and then leveled off for the duration of the study (30 min). The infrared output accounted only for 10% of the total radiated power. CONCLUSIONS: High temperatures are reached by 10 min at the end of fiber optic bundle of light cables and endoscopes with both halogen and xenon light sources. This heat generation is largely due to the radiated power in the visible light spectrum.

Cold Temperature↗
PubMed1998

Computer-controlled endoscopic performance assessment system.

We have devised an advanced computer-controlled system (ADEPT) for the objective evaluation of endoscopic task performance. The system's hardware consists of a dual gimbal mechanism that accepts a variety of 5.0-mm standard endoscopic instruments for manipulation in a precisely mapped and enclosed work space. The target object consists of a sprung base plate incorporating various tasks. It is covered by a sprung perforated transparent top plate that has to be moved and held in the correct position by the operator to gain access to the various tasks. Standard video endoscope equipment provides the visual interface between the operator and the target-instrument field. Different target modules can be used, and the level of task difficulty can be adjusted by varying the manipulation, elevation, and azimuth angles. The system's software is designed to (a) prompt the surgeon with the information necessary to perform the task, (b) collect and collate data on performance during execution of specified tasks, and (c) save the data for future analysis. The system was alpha and beta tested to ensure that all functions operated correctly.

Endoscopy↗
PubMed1998

Ergonomic evaluation of laparoscopic bowel suturing.

BACKGROUND: Ergonomic assessment of the instrument to needle to tissue relationship on efficiency and accuracy of laparoscopic suturing. METHODS: Video records of nine laparoscopic surgeons were analyzed for five technical variables of laparoscopic suturing. Surgeons undertook closure of 60 mm enterotomy using continuous 3/0 seromuscular atraumatic sutures. Subjects attempted to suture 3 to 5 mm from enterotomy edge and at 3 to 5 mm intervals. Vertical/horizontal deviations from desired entry/exit point of suture, execution time, and failure to complete sutures were recorded. RESULTS: Visualization style used by some was significantly more accurate but slower than the nonvisualization style used by others. Needle insertion angle of 80 degrees to 100 degrees gripping the middle and proximal end of needle and holding the needle >90 degrees to instrument axis significantly improved task accuracy. Insertion angle <80 degrees produced three times the failure rate of 80 degrees to 100 degrees. Surgeon's performance was consistent with either suturing style. CONCLUSIONS: Visualization style was slower but more accurate. Optimum conditions for good suturing include 80 degrees to 100 degrees needle insertion angle; holding angle >90 degrees, and gripping point at middle and proximal third of the shaft of the needle. Task accuracy was surgeon dependent.

Colon↗
PubMed1998

Errors enacted during endoscopic surgery--a human reliability analysis.

The aim of the study was to document the nature and incidence of surgical errors enacted during laparoscopic surgery in order to direct future research and surgical training. A modified Human Reliability Analysis (HRA) approach, based on direct observation, was adopted to categorise and record errors encountered during the practice of laparoscopic cholecystectomy. This study confirmed the applicability and usefulness of an observational methodology in the assessment of human error in endoscopic surgical performance. The study identified aspects of the design and usage of instruments, surgical training and the differences between tasks which needed further directed research in order to identify underlying performance shaping factors (PSFs) and so reduce error rates.

Cholecystectomy↗
PubMed1998

Task performance in endoscopic surgery is influenced by location of the image display.

OBJECTIVE: To investigate the influence of image display location on endoscopic task performance in endoscopic surgery. SUMMARY BACKGROUND DATA: The image display system is the only visual interface between the surgeon or interventionist and the operative field. Several factors influence the correct perceptual processing and endoscopic manipulation from images. One of these is location of the image display with respect to the surgeon and to the operative site. The present study was conducted to investigate whether endoscopic task performance improves under two conditions: when the surgeon-to-monitor visual axis is aligned with the forearm-instrument motor axis and when the image display is close to the operator's manipulation workspace. METHODS: An endoscopic task (tying an intracorporeal surgeon's knot) was performed under standardized conditions except for varying monitor locations. These altered the direction of view--in front of, to the left, and to the right of the operator's head and hands. In each of these view directions, the monitor was placed at the surgeon's eye level and lower down, at the level of the operator's hands. The outcome measures were the execution time, knot quality score and performance quality score. RESULTS: Task performance was better with frontal view direction: execution time was shorter (p < 0.0001) and the performance score was higher (p < 0.005) than with side viewing, with no significant difference between right and left viewing directions. With frontal view direction, hand-level "gaze-down" viewing resulted in a shorter execution time (p < 0.01) and a higher performance score (p < 0.01) than eye-level viewing. CONCLUSIONS: Task performance improves when the image display is placed in front of the operator, at a level below the head and close to the hands.

Clinical Competence↗
PubMed1997

Optimal port locations for endoscopic intracorporeal knotting.

Port location is crucial for endoscopic manipulations. The aim of the study was to investigate the influence of manipulation, azimuth, and elevation angles of instruments on endoscopic intracorporeal knotting. The standard task was tying a surgeon's knot. Manipulation angles of 30 degrees , 45 degrees , 60 degrees , 75 degrees , and 90 degrees with equal and unequal azimuth angles and elevation angles of 0 degrees , 30 degrees , and 60 degrees were investigated. The endpoints were the execution time and parameters of knot analysis. The execution time was shorter with 60 degrees than with either 90 degrees or 30 degrees manipulation angles (p < 0.0001 and p < 0. 01). Equal azimuth angles resulted in a shorter execution time than wide unequal angles (p < 0.001). A combination of 60 degrees manipulation angle with 60 degrees elevation angle had the shortest execution time (p < 0.001) and highest performance quality score (p < 0.02). A range of 45 degrees -75 degrees manipulation angles with equal azimuth angles is recommended. As the manipulation angle increases, the elevation angle has to increase accordingly.

Endoscopes↗
PubMed1997

Objective assessment of endoscopic knot quality.

BACKGROUND: Studies of the surgeon's skill and the ergonomics of task performance in endoscopic surgery can be based on knot-tying tasks. The aim of this study was to establish an objective method for assessing the quality of surgical knots for use in such studies. METHODS: In all, 2,700 surgeon's endoscopic knots were studied. Each knot was distracted using a tensiometer, and a computerized system analyzed force-extension curves. The breaking force was taken as an index of knot strength while the force integrated over the slope of the curve reflected knot tightening. A knot quality score (KQS) was obtained from the product of the knot-breaking force and the integrated force expressed as a percentage of the product for the untied ligature. RESULTS: The mean breaking force (24 Newton +/- 2.5) and integrated force (7.4 Newton +/- 2.8) for broken knots were 71% and 35%, respectively, of those for untied ligature. The integrated force yielded a narrower range of variability for untied ligature (SD 3.5% of mean) than for knots (SD 37% of mean). The KQS was higher for broken (25.3%+/-10.3%) than slipped knots (7.1%+/-5.1%). CONCLUSION: The KQS provides a reliable assessment of knot security and reflects the strength and degree of tightening of the knot.

Clinical Competence↗