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A Cuschieri

Publications and source records attributed to A Cuschieri.

At least 73 records · Page 4Linked to original sources
PubMed2001

Perceptual aspects of two-dimensional and stereoscopic display techniques in endoscopic surgery: review and current problems.

The aim of this review is to analyze the perceptual aspects of endoscopic imaging systems. After discussing depth perception in natural settings, the problems of perceiving depth in 2-dimensional representations are investigated. We discuss the impact of stereoscopic video systems on the cerebral perceptual system, emphasising the fact that despite the addition of binocular disparity information, existing stereoscopic video systems are still different from normal 3-dimensional vision. Both 2-dimensional and stereoscopic video systems require a rescaling of visual information to guide motor behavior. A review of the growing number of papers comparing 2-dimensional and stereoscopic video systems shows that only about 50% of investigators found a significant benefit for stereoscopic systems. It is unlikely that image display technology for endoscopic surgery can ever progress to the stage where it is equivalent to normal vision. Within this limitation, progress will result from a multidisciplinary approach, involving technological advances in the quality of the displayed image together with psychovisuomotor and ergonomics research, which facilitates the cerebral rescaling and perception process by the endoscopic surgeon.

Data Display↗
PubMed2001

In situ ablation of hepatic tumors.

The various technologies and approaches for in situ ablation of hepatic tumors are reviewed and the relative merits discussed. The reported experience, though limited, is encouraging but the technology is still maturing. At present in situ ablation ought to be restricted to patients with inoperable disease, unless patients are recruited into randomized trials comparing in situ ablation with hepatic surgical resection in specific patient groups. Emerging technologies such as gene therapy and electro/sonoporation will also impact on how we best manage patients with malignant hepatic tumors. It seems improbable that any one modality will prevail on efficacy, and a more likely scenario for future therapy may well be a combination multimodal approach tailored to the individual patient and the biological characteristics of the tumor.

Cryosurgery↗
PubMed2001

Abdominal wall lift systems in laparoscopic surgery: gasless and low-pressure systems.

Positive pressure pneumoperitoneum (12 mm Hg) is associated with adverse physiologic effects that can prove detrimental to certain high-risk patients with diminished cardiorespiratory reserve. Mechanical abdominal wall lift (AWL) has been proposed as an alternative method of exposure in laparoscopic surgery to obviate or minimize these adverse physiologic effects, the risk of CO(2) embolism in trauma patients, and tumor dissemination in patients undergoing laparoscopic surgery for cancer. This article reviews the systems available for AWL, the clinical applications of the technique, and the findings of the randomized controlled trials that compare AWL with conventional pneumoperitoneum. AWL systems do appear to reduce the adverse cardiovascular and respiratory effects, but they do so at the expense of surgical exposure, which is less optimal than that provided by the positive-pressure pneumoperitoneum. This reduced exposure increases the execution difficulty of the operation and, hence, the operating times. This problem is overcome by combination of AWL with low-pressure (3 to 4 mm Hg) pneumoperitoneum. This combination provides good surgical exposure without adverse cardiovascular consequences.

Humans↗
PubMed2001

Tissue adhesives in endosurgery.

Usage of tissue adhesives/glues for tissue approximation and hemostasis is increasing as the related technology advances. There is no accepted classification, but surgical adhesives fall into 3 main categories: biological, synthetic, and genetically engineered polymer protein glues. Nonresorbable glues should be confined only to surface application, such as closure of the wound edges. Adhesives for internal use, including hemostasis, tissue edge approximation, mesh hernioplasties, sealing of cerebrospinal fluid (CSF) fluid and intestinal leaks, and anastomoses, should be biocompatible and resorbable. In time, tissue glues and soldering will likely replace, in whole or in part, the use of sutures and staples for a variety of tissue approximation surgical procedures.

Cyanoacrylates↗
PubMed2001

Ergonomics of hand-assisted laparoscopic surgery.

Hand-assisted laparoscopic surgery (HALS) facilitates complex or advanced laparoscopic operations without appreciable loss of the advantages of the total laparoscopic approach. The internal hand enables atraumatic exposure and stretching of tissue planes, finger dissection, restores palpation of internal organs and structures, and provides a rapid and effective means of hemostasis. Particularly during complex surgery performed on the liver and pancreas, this ability to control bleeding by placing pressure between the index finger and thumb reduces the stress on the surgeon. HALS does, however, carry a number of ergonomic problems that are consequent on the encroachment of the hand and device on the workspace. It also imposes an awkward lordotic stance, hence back and shoulder strain on the surgeon. These problems can be resolved by further development of the hand-access devices and also with modifications of existing laparoscopic instruments, or the design and development of HALS-dedicated specific instrumentation. Further progress and increased scope of HALS will only be achieved with designs based on ergonomic research.

Equipment Design↗
PubMed2001

Laparoscopic hand-assisted hepatic surgery.

At Ninewells Hospital, we have changed from total to hand-assisted laparoscopic hepatic resections. We report here our initial experience on 10 anatomic hepatic resections with good outcome, and 1 with a significant postoperative complication (fall in the hemoglobin) requiring laparotomy. All resections were undertaken by using the Omniport device (Advanced Surgical Concepts, Dublin, Ireland). The hand-assisted laparoscopic surgery (HALS)-Omniport approach has also been used selectively in 5 patients undergoing in situ ablation for bilateral metastatic disease with lesions not easily accessible to the total laparoscopic approach, ie, situated in the posterior and inferior segments of the right liver. The HALS approach has several advantages; it facilitates and expedites the procedure, reduces the stress factor to the surgeon, greatly improves exposure, and provides an immediate and efficient control of bleeding vessels with the internal hand. The Omniport device, which essentially consists of a handcuff with a spiral inflatable valve, enables withdraw and reinsertion of the hand without loss of pneumoperitoneum during the procedure. The device was effective in maintaining pneumoperitoneum in all cases. All operations were completed with the HALS approach.

Adult↗
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

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

Laparoscopic hand-assisted surgery for hepatic and pancreatic disease.

Herein I describe my initial experience with the use of a novel device, the Omniport, in 15 patients undergoing hand-assisted laparoscopic surgery (HALS) on the liver and pancreas. The device, which essentially consists of a hand cuff with a spiral inflatable valve, enables withdrawal and reinsertion of the hand without loss of pneumoperitoneum during the operation. The cuff's effective sealing pressure is equal to the pneumoperitoneal pressure; hence, hand comfort is maintained during the intervention. The device was effective in maintaining pneumoperitoneum in all cases. All but one operation was completed with the HALS approach. The one conversion was due to bleeding from the superior mesenteric vein during a 90% pancreaticosplenectomy. Immediate effective control of the bleeding by compression between the thumb and index finger was achieved, and the cuff of the Omniport was deflated as the incision was enlarged. There were no postoperative complications. The HALS approach has distinct advantages in terms of exposure and safety over the total laparoscopic technique for major surgery on the liver and pancreas, and it is recommended for these interventions.

Adult↗
PubMed2000

Patch incorporation in diaphragmatic hernia.

BACKGROUND/PURPOSE: Biomaterial insertion often is required for closure of congenital diaphragmatic hernia (CDH). The optimal biomaterial remains uncertain. This study was designed to compare a commonly used patch (polytetrafluoroethylene) with a recently available fabric, fluorinated polyester. The aim of this study was to determine the clinical performance, histological tissue-polymer interaction, bacterial adhesion, and shrinkage rates of biomaterial inserted endoscopically into a CDH lamb model. METHODS: Polytetrafluoro-ethylene (PTFE) and fluorinated polyester (FP) were randomised for laparoscopic patch insertion into 12 lambs. All lambs (age <4 weeks) underwent 3-port laparoscopy, surgical creation of diaphragmatic hernia, and sutured patch placement. Two PTFE and 2 FP lambs were killed at 1-, 3-, and 6-month intervals postoperatively. Postmortem examination histopathology, electron microscopy, and specific bacterial broth immersion (Escherichia coil, Staphylococcus aurens, and epidermidis) were performed. RESULTS: All 12 lambs completed the study with intact patches that were fully peritonised. One abdominal adhesion was noted in a FP lamb at 6 months. FP was comparatively easier to insert, manipulate, and suture endoscopically. Histopathology findings showed that PTFE patches created a strong peripheral foreign body reaction with dystrophic calcification, whereas FP was well incorporated with intrapatch fibroblastic activity and neovascularsation. No significant difference in resistance to bacterial adhesion of relevant organisms was noted between the materials. Graft shrinkage for FP was 7% in one direction only, evident by 3 months. CONCLUSIONS: Fluorinated polyester has advantages in this laparoscopic lamb model. It shows rapid and sustained incorporation with intrapatch neovascularisation when compared with polytetrafluoro-ethylene's significant foreign body reaction. It was preferred for its endoscopic handling and suturing properties. The laparoscopic techniques used may contribute to the general lack of adhesions, and insufficient data are available to comment on the comparative effect of the materials on adhesion formation. No difference was demonstrated in resistance to bacterial adherence in the harvested materials.

Animals↗
PubMed2000

Laparoscopic gastric resection.

This article focuses on laparoscopic gastric resections for neoplastic disease, gastric cancer, and gastric mesenchymal tumors. Established oncologic principles governing resections for neoplastic disease must not be overlooked in the laparoscopic approach to surgical management. Evidence-based information on surgical management of gastric cancer and stromal stomach tumors is presented, and the laparoscopic procedures that can be undertaken without compromising the clinical outcome are surveyed.

Evidence-Based Medicine↗
PubMed2000

Preface

Explore the source record for details and available documents.

Journal Article↗
PubMed2000

Sample size calculation for clinical trials: the impact of clinician beliefs.

The UK Medical Research Council (MRC) randomized trial of gastric surgery, ST01, compared conventional (D1) with radical (D2) surgery. Sample size estimation was based upon the consensus opinion of the surgical members of the design team, which suggested that a change in 5-year survival from 20% (D1) to 34% (D2) could be realistic and medically important. On the basis of these survival rates, the sample size for the trial was 400 patients. However, this trial was exceptional in the way that a survey of surgeons' opinions was made at the start of the trial, in 1986, and again before results were analysed but after termination of the trial in 1994. At the initial survey, the three surgeons from the trial steering committee and 23 other surgeons experienced in treating gastric carcinoma were given detailed questionnaires. They were asked about the expected survival rate in the D1 group, anticipated difference in survival from D2 surgery, and what difference would be medically important and influence future treatment of patients. The consensus opinion of those surveyed was that there might be a survival improvement of 9.4%. In 1994, prior to closure of the trial, and before any survival information was disclosed, the survey was repeated with 21 of the original 26 surgeons. At this second survey, the opinion of the trial steering committee was that 9.5% difference was more realistic. This was in accord with the opinion of the larger group, which remained little changed since 1986. The baseline 5-year D1 survival was thought likely to be about 32%, which corresponded closely to the actual survival of recruited patients. Revised sample size calculations suggested that, on the basis of these more recent opinions, between 800 and 1200 patients would have been required. Both surveys assessed the level of treatment benefit that was deemed to be sufficient for causing surgeons to change their practice. This showed that the 13% difference in survival used as the study target was clinically relevant, but also indicated that many clinicians would remain unwilling to change their practice if the difference is only 9.5%. The experience of this carefully designed trial illustrates the problems of designing long-term, randomized trials. It raises interesting questions about the common practice of basing sample size estimates upon the beliefs of a trial design committee that may include a number of enthusiasts for the trial treatment. If their opinion of anticipated effect sizes drives the design of the trial, rather than the opinion of a larger community of experts that includes sceptics as well as enthusiasts, there is likely to be a serious miscalculation of sample size requirements.

Bayes Theorem↗
PubMed2000

Minimally invasive surgery: hepatobiliary-pancreatic and foregut.

This review is confined to the liver, biliary tract, pancreas, and foregut (oesophagus and stomach). The issues relating to laparoscopic cholecystectomy mainly concern the bile duct injuries associated with this operation. This review provides some evidence that although the risk for this iatrogenic injury is declining, it continues to be a problem and is accompanied by significant morbidity, mortality, and a huge escalation in care costs. Laparoscopic clearance of ductal stones is undoubtedly safe and effective, and issues have now focused on comparisons between this form of management and orthodox endoscopic clearance. Laparoscopic cardiomyotomy may well replace other forms of treatment of achalasia, including balloon dilation and botulinum toxin injection. As the results of laparoscopic antireflux surgery have been so good in the medium term, the question of medical versus laparoscopic treatment is being addressed by two randomized clinical trials. Gastric resection is established only in respect of excision of mesenchymal tumours. Gastric surgery for advanced gastric cancer must still be regarded as developmental. Laparoscopic liver resections and in situ ablation are still confined to developing centres, but the early results are promising. However, simpler hepatic procedures, such as de-roofing of symptomatic simple hepatic cysts, are well established and in widespread practice. Only a few centres have published their results on laparoscopic pancreatic surgery. The early reported outcome for internal drainage of pancreatic pseudocysts, enucleation of benign insulinomas, and distal pancreatic resections has been good, but the experience is limited.

Bile Duct Neoplasms↗
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↗