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Biomedical subjects

A Cuschieri

Publications and source records attributed to A Cuschieri.

At least 37 records · Page 2Linked to original sources
PubMed2004

Prevention of lens condensation in laparoscopic surgery by lens heating with a thermos flask.

Condensation on the scope lens as a result of differences between room and intraabdominal temperatures is a disturbing problem for laparoscopic surgeons. Despite the use of anti-lens condensation solutions, this cannot be entirely avoided. The authors report a simple, cheap, and effective method for preventing lens condensation by lens heating using a sterilized thermos flask filled with hot water.

Body Temperature↗
PubMed2004

Effect of fixation of shoulder and elbow joint movement on the precision of laparoscopic instrument manipulations.

BACKGROUND: Motion analysis of the upper limb and the surgical instruments is used for objective assessment of endoscopic manipulations. The aim of this study was to investigate the effect of fixation of shoulder and elbow joint movement on the precision of laparoscopic instrument manipulations. METHODS: Two experiments were conducted to correlate hand movement with instrument tip during free and restricted movement of the shoulder and elbow joints. A three-dimensional infrared optical tracking system has been used. Five subjects participated in the study, and each completed the range of movements twice. End points were velocity (m/s), angular velocity (r/s) and acceleration (m/s2). RESULTS: There was a weak correlation for all end points between the instrument tip and individual joint movement during free upper limb movement (r < 0.4). With restricted movement of the shoulder and elbow joints, the correlation between hand movement and instrument tip was found to be good for the velocity (r = 0.66 for flexion; r = 0.72 for abduction; r = 0.56 for supination) and angular velocity (r = -0.83 for flexion; r = -0.48 for abduction; r = -0.70 for supination), but weak for the acceleration (r < 0.4). CONCLUSIONS: The characteristics of hand movements do not correlate with movement of the laparoscopic instrument tip when the upper limb is unsupported. The precision of laparoscopic surgical manipulations is increased if both joints (shoulder and elbow) are supported.

Elbow Joint↗
PubMed2004

Assessing the benefits of "gaze-down" display location in complex tasks.

BACKGROUND: Location of the image display is one of several factors that influence perceptual processing and endoscopic manipulation in minimal access surgery. Previous studies have proved the benefits of the gaze-down stance, as compared with the conventional gaze-up stance. This study investigates the effect of the gaze-down stance on the performance of a task with varying manipulative and perceptual demands. METHODS: The participants in this study were 20 medical students. Each student performed endoscopic touching tasks under standard conditions using the Dundee Projection System (DPS) display, positioned to provide gaze-up and gaze-down stances. To increase task complexity, two kinds of manual coordination (unilateral vs bilateral) and three endoscope positions (different positions of misalignment) were used. The outcome measures were task execution time and number of errors. RESULTS: Overall, the gaze-down stance reduced time and errors, as compared with the gaze-up display. However, the benefit obtained from the gaze-down stance was more significant in the more difficult tasks (bilateral task and 90 degrees misalignments). CONCLUSIONS: The gaze-down stance reduces task time and errors, as compared with a gaze-up stance. The reduction in time and errors is more appreciable as task complexity increases.

Laparoscopy↗
PubMed2004

Analysis of technical surgical errors during initial experience of laparoscopic pyloromyotomy by a group of Dutch pediatric surgeons.

BACKGROUND: The adoption of laparoscopic pyloromyotomy (LPM) by pediatric surgeons has been limited due to concerns about long execution times and higher-than-expected morbidity. The aim of the present study was to examine the performance of LPM by pediatric surgeons during the initial stages of their experience. METHODS: Complete videotapes of 50 early LPM performed in one hospital were subjected to Observational Clinical Human Reliability Analysis (OCHRA) by an independent team. RESULTS: This series had a total morbidity of 6% (one intraoperative bleed, one gastric perforation, one incomplete pyloromyotomy). Using OCHRA, we identified 77 consequential and 233 inconsequential errors (mean of 6 +/- 5.4 per operation, 16.7% total error probability) during an average operative time of 29.8 min. Eighty percent of the errors were of the execution type. A high probability of error was observed with the use of the following key instruments: holding graspers (68%), retractable blade (79%), and splitting forceps (77%). The OCHRA system confirmed that task III was the hazard zone for LPM. Excessive force (task III) resulted in gastric perforation and bleeding from the pyloric mass. Movement in the wrong direction and misorientation in tissue planes were the external error modes underlying misaligned cuts of the pyloric mass and poor tissue splitting (task zones II and III). CONCLUSIONS: This early series of LPM was associated with an appreciable execution error rate, largely due to the poor functionality of the specific instruments used for the procedure. Human factors identified by the external error modes played a subsidiary but important role, underscoring the importance of skills training and experience (proficiency-gain curve).

Child↗
PubMed2004

Time-motion analysis of operation theater time use during laparoscopic cholecystectomy by surgical specialist residents.

BACKGROUND: Data on man-machine interfaces in the operation theater are essential to the improvement of surgical efficiency. This study analyzed the activity of the operating team during laparoscopic cholecystectomy by surgical trainees. METHODS: The endoscopic image and overview of the operating room were recorded during 20 laparoscopic cholecystectomies performed by specialist residents. Time-motion analysis of the recorded tapes was performed. RESULTS: The median (interquartile range [IQR]) for theater time was 134 +/- min (IQR, 52 min). The components of operative time for the surgeon were 26% for insertion of access ports and wound closure, 57% for intracorporeal endoscopic work, and 17% for instrument change. Only 52% of the scrub nurse time was related to the operation. Machine and video setup, adjustment of ancillary equipment together, and delivery of instruments and items requested by the surgeon and scrub nurse accounted for 13% of the circulating nurse time. CONCLUSIONS: With the current nonergonomic theater design and structure, a significant proportion of theater time during routine uncomplicated laparoscopic surgery is used for nonoperative functions. The study highlights the need for improved ergonomic design, integrated bus operating systems under the control of the surgeon, and multifunctional laparoscopic instruments.

Cholecystectomy, Laparoscopic↗
PubMed2004

Improving the retention of suturing needles in surgical graspers.

BACKGROUND: Surgical needles are usually held using dedicated grasping instruments. When the tissue to be penetrated is resilient, or the grasping force is low, the needle can swivel, causing it to deviate from the intended path, resulting in suboptimal tissue approximation. Needle swivel is particularly prevalent when needles are not held transversely in the jaws, but it is difficult to maintain a transverse grasp during surgery. An improved swivel-resistant grasper design is proposed. METHODS: Conventional and swivel-resistant graspers were tested to quantify the benefits of the swivel-resistant design. Needles secured in the grasper were repeatedly distracted until swiveling occurred. The torque required to swivel the needles was statistically analyzed. RESULTS: The swivel-resistant grasper offers greatly improved resistance to swivel (p = 0.01) when the needle is not held transversely. CONCLUSIONS: The four-point contact afforded by the modified needle graspers imparts improved needle retention and resistance to swivel.

Equipment Design↗
PubMed2004

Characterizing the "gold standard" image for laparoscopic surgery.

BACKGROUND: The term "gold standard" is often used to describe preferred display devices, frequently without substantiating evidence. A meaningful and objective measure of display quality for endoscopic surgery is required. METHODS: Typical colors from five tissue types were arranged in a striped pattern and displayed on four devices: a medical-grade cathode ray tube monitor, a liquid crystal display, a digital light projection display, and an obsolete cathode ray tube (CRT) monitor. The breadth and color contrast of the stripes were adjusted until the patterns became indiscernible to 12 subjects. The data provide a discernibility threshold. RESULTS: The liquid crystal display (LCD) monitor provided the best image. The medical grade and obsolete CRTs were second and third, respectively, and the projection display provided the most inferior image. CONCLUSIONS: A meaningful and relevant measurement of image display quality for laparoscopic surgery based on the discernibility threshold is provided. Of the devices tested, the LCD is the best in terms of image, although the CRT may be preferred at off-axis viewing angles. The projection system, however, offers compensatory ergonomic advantages.

Benchmarking↗
PubMed2004

Cardiovascular autonomic function in patients with hemodynamic instability at induction of capnoperitoneum: a case-control study.

BACKGROUND: This study hypothesized that patients in whom bradycardia and hypotension develop with induction of positive-pressure capnoperitoneum have an underlying autonomic cardiovascular dysfunction. METHODS: A case-control study was conducted to examine the baseline autonomic function of patients in whom bradycardia and hypotension develop with induction of positive-pressure capnoperitoneum. The control group consisted of patients who maintained normal cardiac rhythm and blood pressure during the same procedure. Two groups of tests were performed: bedside stress tests of cardiovascular autonomic function (response graded 1 (normal) to 4 (severely abnormal) and heart rate variability analysis (spectral and time domain components). RESULTS: The study evaluated 6 patients in the bradycardia group and 10 in the control group. The group in whom bradycardia had developed scored significantly worse on the bedside stress tests than the control group (for grades I to IV: chi2 = 6.5, p = 0.022; for trend: chi2 = 5.6, p = 0.018). In contrast, both groups had similar baseline autonomic tone, as measured by heart rate variability. CONCLUSIONS: Patients in whom bradycardia and hypotension develop with induction of positive-pressure capnoperitoneum have cardiovascular autonomic dysfunction, which is identifiable by bedside stress tests of autonomic function.

Autonomic Nervous System↗
PubMed2004

Identification and categorization of technical errors by Observational Clinical Human Reliability Assessment (OCHRA) during laparoscopic cholecystectomy.

HYPOTHESIS: Surgical operative performance benefits from analysis of the mechanisms underlying technical errors committed during surgery. DESIGN: Prospective study using the Observational Clinical Human Reliability Assessment (OCHRA) system and complete unedited videotapes of the operations. SETTING: Three National Health Service hospitals within the United Kingdom. PATIENTS: Two hundred consecutive patients with symptomatic gallstone disease. INTERVENTIONS: Elective laparoscopic cholecystectomy for symptomatic gallstone disease by surgeons, who were blind to the nature and objectives of the study, using their usual operative technique. MAIN OUTCOME MEASURES: Surgical consequential and inconsequential operative errors. RESULTS: The analysis of 38 062 steps of the 200 laparoscopic cholecystectomies performed by 26 surgeons identified 2242 errors. The mean +/- SD total, inconsequential, and consequential errors per surgical procedure were 11.0 +/- 8.0, 8.0 +/- 6.0, and 4.0 +/- 3.0, respectively. Dissection of the Calot triangle (second task zone of the operation) incurred more total errors (6.5 +/- 5.4) compared with the first (2.9 +/- 2.8, P<.001) and third (5.1 +/- 3.9, P<.05) task zones. This translated to a higher error probability (6.9% vs 3.5% for the first and 5.5% for third task zones). The combined sharp and blunt dissection method had fewer errors than the blunt/teasing dissection technique (9.45 +/- 7.6 vs 13.9 +/- 7.3, P<.001) although different surgeons were involved. The most serious consequences were encountered during dissection with the electrosurgical hook knife. CONCLUSION: This study has confirmed that the Observational Clinical Human Reliability Assessment system provides a comprehensive objective assessment of the quality of surgical operative performance by documenting the errors, the stage of the operation in which errors are enacted most frequently, and where these errors have serious consequences (hazard zones).

Cholecystectomy, Laparoscopic↗
PubMed2003

Effect of the angle between the optical axis of the endoscope and the instruments' plane on monitor image and surgical performance.

BACKGROUND: The aim of the study was to examine the effect of the angle between optical axis of the endoscope and the instruments' plane (OAIP) on the monitor display angle (approach angle between the two instruments on a two-dimensional monitor) and endoscopic task performance. METHODS: Two experiments were carried out in the Advanced Dundee Endoscopic Psychomotor Tester (ADEPT) using a standard two-dimensional video endoscopic system. In the first experiment, the monitor display angle was measured during use, with OAIP angles ranging between 0 and 80 degrees (at 10 degrees increments) and manipulation angles varying between 45 and 120 degrees (at 15 degrees increments). In the second experiment, 10 surgeons tied 500 intracorporeal knots with OAIP angles of 0 degrees (optical axis in the same plane as the instruments), +15 degrees and +30 degrees (viewing above the instruments' plane), and -15 and -30 degrees (optical axis looking from below instruments' plane). The end points were the execution time and knot quality score (KQS). RESULTS: In the first experiment, instruments entered the visual field from lateral sides of the monitor with an apparent 180 degrees monitor display angle with a 0 degrees OAIP angle, whereas the monitor display angle approached the actual manipulation angle between the two needle drivers when an 80 degrees OAIP angle was used. In the second experiment, the instruments appeared to enter the image field from the side of the surgeon when the endoscope viewed the instruments from above, whereas instruments entered the field from the opposite side to the surgeon when the endoscope viewed instruments' plane from below. As a result, use of 0 and +15 degrees OATP angles yielded significantly shorter execution times: 70 s compared to 83, 93, and 77 s for +30, -30, and -15 degrees OAIP angles ( p < 0.001), with KQS of 39 degrees and 40 vs 38, 36, and 34%, respectively ( p = 0.257). CONCLUSIONS: The angle between the optical axis of the endoscope and instruments' plane determines how the instruments appear to enter the operative field. The monitor display angle between the instruments is different from the real manipulation angle unless the OAIP angle is near 80 degrees. The apparent entry of instruments into the operative field becomes intuitive for the surgeon only if the endoscope is viewing from above or in the same plane as the instruments. Hence, the best performance for endoscopic knot tying is obtained with this configuration, and execution time increases significantly with viewing from below the instruments' plane.

Endoscopes↗
PubMed2003

Multimedia article. Laparoscopic infracolic necrosectomy for infected pancreatic necrosis.

Infected pancreatic necrosis carries a high morbidity and mortality from sepsis and multisystem organ failure. Following confirmation of the infection by CT-guided fine needle aspiration, treatment consists of broad spectrum antibiotics (imipenim-cilastin) followed by emergency open (laparotomy) digital necrosectomy and insertion of drains for postoperative lavage with hyperosmolar dialysate as advocated by Beger et al. This video shows an alternative laparoscopic technique to open necrosectomy and has been used in Dundee since 1994. After elevation of the transverse colon, the lesser sac is opened through the root of the transverse colon between the middle and left colic vessels. The necrosectomy is accomplished from inside the lesser sac under vision with a combination of pulsed irrigation and graspers. On completion of the necrosectomy, two large drains are inserted into the lesser sac for postoperative irrigation. The experience with this technique has been favorable with a patient survival of 85%.

Bacterial Infections↗
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↗
PubMed2003

A new multitool for hand-assisted advanced laparoscopic surgery (HALS).

BACKGROUND: Hand-assisted laparoscopic surgery (HALS), which has become possible due to the introduction of effective hand-access devices, facilitates the execution of major operations. Over the past 2 years, we have been evaluating various designs for small instruments that can be used by the internal assisting hand. Here we report on the development, testing, and evaluation of a small reusable multitool that hangs from the little finger of the internal assisting hand of the surgeon when not in use. METHODS: The Dundee Multitool (DMT) was designed to enable the internal deployment (by thumb extrusion) of a small dissecting forceps (pickup), needle driver, and scissors. The multitool hangs from the little finger of the internal assisting hand when not in use. The instrument was subjected to beta testing in the laboratory using HALS trainers. When testing was completed, it was used in major HALS operations after approval by the hospital and consent of the individual patients. RESULTS: The DMT was found to work well. The various active instruments could be extruded from the casing with ease and functioned well in picking up tissues, intracorporeal suturing/tying, and the cutting of sutures and ligatures. Both in laboratory experiments and during clinical evaluation, suturing was easy when the active driving of the needle though the tissues was carried out by the external hand. The multitool needle driver, held by the internal hand as an assisting instrument in conjunction with active needle driving through the tissue edges by the dominant (external) hand, improved suturing efficiency (i.e., reduced execution time) by 30% when compared to total laparoscopic suturing. CONCLUSIONS: We have described a novel little-finger-hung multitool for HALS surgery that deploys with ease at any one time. It incorporates a needle driver, a dissecting forceps, and a suture scissors. The good functionality of the multitool has been confirmed by both laboratory experiments and clinical evaluation.

Animals↗
PubMed2003

Optimization of the projection screen in a display system for minimal access surgery.

BACKGROUND: The operative image for minimal access surgery currently is displayed on a monitor located outside the sterile field. It is ergonomically advantageous to locate the image adjacent to the surgeon's hands by projection onto a sterile screen, but there has been no research into the optimal screen material. METHODS: Several screen materials were compared for image resolution, brightness, variation of brightness with viewing angle, and image artifact. RESULTS: Glossy materials perform poorly, whereas finely grained surfaces improve image clarity. Excessive roughness and incomplete opacity limit the image resolution. Conventional screen fabrics are unsuitable in this application. Ambient lighting and projector brightness affect image contrast, but a correct choice of material can address this. Practical issues such as moisture absorbency and ease of sterilization are considered. CONCLUSIONS: Potential screen materials were rejected because of excessive glare, poor resolution, and image artifact. Finely textured surfaces (e.g., polystyrene sheeting) provide an acceptable screen.

Artifacts↗
PubMed2003

Comparison of conventional and gaze-down imaging in laparoscopic task performance.

BACKGROUND: In video-assisted laparoscopy, the image is usually displayed on a monitor placed at approximately eye level. Video projection systems project the image onto a screen placed close to the hands. This is said to be ergonomically superior. To evaluate this approach, a proprietary projection system (PS) was compared to a monitor display (MD). METHOD: The resolution, ghosting, flickering, glare, contrast, color smear, and color matching of the two modalities were compared. A bowel-suturing task was employed to evaluate performance differences. RESULTS: The image displayed by the first-generation PS is inferior to that of the MD in contrast and resolution measures, but it is comparable in the other image qualities. No significant differences in task performance were identified. CONCLUSIONS: The first-generation PS does not confer performance or comfort advantages over an MD. The theoretical advantages of the gaze-down stance are likely to be realized only if a high-quality projector is used.

Clinical Competence↗
PubMed2002

Metrics for objective Assessment.

As the need for improved methods of assessing surgical competence grows, it is imperative to establish the basic infrastructure to ensure the ability to communicate among educators, education researchers, responsible training bodies, and credentialing boards. A workshop was conducted to provide a foundation for communication and a standardization of definitions, measurements, and criteria. Future conferences and workshops will be needed to review and refine this initial framework.

Australia↗