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PubMed2001

Training background as a factor in the conversion rate of laparoscopic cholecystectomy.

The present study reports findings concerning the impact of the learning environment on the conversion rate of laparoscopic cholecystectomy (LC) to open cholecystectomy (OC). At Metro-West Medical Center (Framingham, MA) seven surgeons performed 866 LCs between 1990 and 1995. Group I consisted of three surgeons who learned the procedure as part of their General Surgery Residency training, whereas the remaining four surgeons representing Group II learned the procedure through private courses. We emphasize the importance of the surgeons' training background on the conversion rates, operative times, and length of hospitalization for patients undergoing LC. The conversion rates, operative times, and complication rates were analyzed with and without a 2-year period of adjustment to compensate for the learning curve of early procedures. Operative times and conversion rates from LC to OC were lower for cases done by surgeons from Group I, even when the learning curve was corrected. The complication rates were higher for surgeons in Group II, but this did not reach statistical significance. As surgeons from Group II gained more experience their operation times and conversion rates decreased. However, there still was a statistically significant difference in favor of surgeons who learned the procedure as part of a structured curriculum. These data suggest a long-lasting influence of the learning environment on the conversion rates and operative times.

Adolescent↗

PubMed2006

[Laparoscopic surgery in urology: Taining and education].

Relatively long learning curves and, therefore, initially longer operating times compared to conventional procedures are still a matter of debate. Today, there are numerous possibilities for learning laparoscopic techniques and establishing one's own laparoscopic programs, including various pelvitrainers and virtual reality computer programs. One useful and realistic way involves "wet lab" training programs for ablative and reconstructive procedures using the pig model. Today, laparoscopic urological surgery includes procedures with low (e.g. laparoscopy for undescended testicles), intermediate (laparoscopic pyeloplasty) and high level (laparoscopic/endoscopic prostatectomy) complexity. Therefore, laparoscopy should be an integral part of training in urology. A defined number of possibly multi-institutional training centers with well structured educational programs are needed. The main goal should be the standardization of surgical procedures as well as educational training programs in order to shorten individual learning curves and generate common quality standards.

Animals↗

PubMed2004

Sources of variability on the estimate of treatment effect in the PROWESS trial: implications for the design and conduct of future studies in severe sepsis.

OBJECTIVE: To elucidate sources of variability in the estimate of treatment effects in a successful phase 3 trial in severe sepsis and to assess their implications on the design of future clinical trials. DESIGN: Retrospective evaluation of prospectively defined subgroups from a large phase 3, placebo-controlled clinical trial (PROWESS). SETTING: The study involved 164 medical centers. PATIENTS: Patients were 1,690 patients with severe sepsis. INTERVENTIONS: Drotrecogin alfa (activated) (Xigris) 24 microg/kg/hr for 96 hrs, or placebo. MEASUREMENTS AND MAIN RESULTS: All prospectively defined subgroups were examined to identify treatment effects that potentially differed across subgroup strata (assessed by Breslow-Day p < .10). Potential interactions were identified for subgroups defined by a) presence vs. absence of a significant protocol violation (p = .07); b) original vs. amended protocol (p = .08); and c) Acute Physiology and Chronic Health Evaluation (APACHE) II quartile at baseline (p = .09). No treatment benefit was observed in patients having a protocol violation, regardless of type. There appeared to be less treatment effect in patients enrolled under the original vs. amended protocol. The risk ratio exceeded 1.0 for patients in the lowest APACHE II score quartile. A highly significant correlation was observed between the sequence of enrollment at a site, the frequency of protocol violations, and the observed treatment effect. As enrollment increased, frequency of protocol violations decreased (p < .0001) and the treatment effect improved. The correlation between the sequence of enrollment and improvement in treatment effect remained even after removal of patients with protocol violations. Removal of the first block of patients at each site from the analysis reduced the extent of interaction by protocol version and APACHE II score. CONCLUSIONS: A learning curve appeared to be present within the PROWESS trial such that the ability to demonstrate efficacy improved with increasing site experience. This potential learning curve may have implications for design of future trials. Investigational sites may need to require a minimum level of protocol-specific experience to appropriately implement a given trial. This experience should be an important consideration in designing trials and analysis plans. Diligence by coordinating centers, site investigators, study coordinators, and sponsors is necessary to ensure that the protocol is executed as designed such that a treatment benefit, if present, will be evident.

APACHE↗

PubMed1992

Adventitious control by the location of comparison stimuli in conditional discriminations.

In a conditional discrimination procedure, samples appeared in a center key, and comparisons appeared in two of four outer keys. The location of comparison keys varied from trial to trial. Separate learning curves for each of the six possible pairs of comparison keys were plotted in a signal-detection space, revealing different patterns of progress on each pair. Also, when learned conditional discriminations were disrupted, pairs of keys differed in their patterns of disruption. Varying the location of comparison stimuli among six different pairs of keys had not eliminated key position as a controlling aspect of the stimuli. The variations simply increased the number of stimulus compounds--key position and experimental stimuli--that the subject learned. Plotting conditional-discrimination learning curves in a signal-detection space reveals relations among hits, false alarms, accuracy, and comparison preference that help to define a subject's progress.

Animals↗

PubMed2006

Generalized approach for modeling minimally invasive surgery as a stochastic process using a discrete Markov model.

Minimally invasive surgery (MIS) involves a multidimensional series of tasks requiring a synthesis between visual information and the kinematics and dynamics of the surgical tools. Analysis of these sources of information is a key step in defining objective criteria for characterizing surgical performance. The Blue DRAGON is a new system for acquiring the kinematics and the dynamics of two endoscopic tools synchronized with the endoscopic view of the surgical scene. Modeling the process of MIS using a finite state model [Markov model (MM)] reveals the internal structure of the surgical task and is utilized as one of the key steps in objectively assessing surgical performance. The experimental protocol includes tying an intracorporeal knot in a MIS setup performed on an animal model (pig) by 30 surgeons at different levels of training including expert surgeons. An objective learning curve was defined based on measuring quantitative statistical distance (similarity) between MM of experts and MM of residents at different levels of training. The objective learning curve was similar to that of the subjective performance analysis. The MM proved to be a powerful and compact mathematical model for decomposing a complex task such as laparoscopic suturing. Systems like surgical robots or virtual reality simulators in which the kinematics and the dynamics of the surgical tool are inherently measured may benefit from incorporation of the proposed methodology.

Computer Simulation↗

PubMed1994

Advances in laparoscopic renal and ureteral surgery.

With the introduction of laparoscopy into adult urology, a vast new field has suddenly opened itself up to the urologic surgeon, filled with exciting and promising possibilities of applying the principles of minimally invasive surgery to an ever increasing number of diseases that so far have only been approachable by incisional surgery. While undoubtedly, laparoscopy has been providing unprecedented challenges to the principles of open surgery, it is of paramount importance to critically evaluate each new laparoscopic procedure against its open surgical counterpart. However, despite a widely publicized higher complication rate for laparoscopic procedures, it must not be overlooked that each laparoscopist must go through his/her very own individual learning curve; although a painful process at times, it is not any different than the novice's introduction to open incisional surgery. The problems of the learning curve can be partly alleviated by carefully studying the basic principles of laparoscopy in the animal laboratory, and by subsequent clinical training under the guidance of an experienced laparoscopist. The discoverer's enthusiasm for his or her own newly developed procedure and the instinctive negative reaction of the practicing community to new concepts that threaten to overturn what is perceived as 'tried and true', must both be tempered by the accumulation of clinical data, testing the validity of all procedures, new and old alike. To this end, surgeons have the opportunity to explore a gentler form of surgical practice, one in which the practitioner can heal without the need to harm.

Humans↗

PubMed2003

Minimally invasive surgery task decomposition--etymology of endoscopic suturing.

The analogy between Minimally Invasive Surgery (MIS) and the human language inspires the decomposition of a surgical task into its primary elements. The frequency of different elements or words" and their sequential associations or "grammar" both hold critical information about the process and outcome of the procedure. Modeling these sequential element expressions using a multi finite states model (Markov model) reveals the grammatical structure of the surgical task and is utilized as one of the key steps in objectively assessing surgical performance. The experimental protocol included 30 surgeons at different levels of training (5xR1,R2,R3,R4,R5, and experts) performing Laparoscopic suturing on an animal model (pig). The kinematics and dynamics of left and right endoscopic tools along with the visual view of the surgical scene were acquired by the Blue DRAGON system. The methodology of decomposing the surgical task is based on a fully connected, finite-states (30 states) Markov model (MM) where the left and right hands are represented by 15 states each. In addition to the MM objective analysis, a scoring protocol was used by an expert surgeon to subjectively assess the subjects' technical performance. An objective learning curve was defined based on measuring quantitative statistical distance (similarity) between MM of experts and MM of residents at different levels of training. The objective learning curve (e.g. statistical distance between MM) was similar to that of the subjective performance analysis. The MM proved to be a powerful and compact mathematical model for decomposing a complex task such as laparoscopic suturing. Systems like surgical robots or virtual reality simulators that inherently measure the kinematics and dynamics of the surgical tool may benefit from inclusion of the proposed methodology for analysis of efficacy and objective evaluation of surgical skills during training.

Endoscopy↗

PubMed2004

Clinical skills acquisition for hand-assisted laparoscopic donor nephrectomy.

PURPOSE: The learning curve associated with laparoscopic surgery may be associated with higher patient risk, and in the setting of kidney donation such risk may be unacceptable. We characterize the learning curve for hand-assisted laparoscopic donor nephrectomy in the context of a urology training program, and establish a case volume threshold after which improvements in laparoscopic skill can be demonstrated. MATERIALS AND METHODS: The study included 245 consecutive laparoscopic cases, including 111 donor nephrectomies, performed in 2 (1/2) years to characterize various measures of experience. Documentation of resident involvement in each case was made by a single surgeon and collected prospectively. Outcomes assessed included operative time, blood loss and intraoperative complications. RESULTS: Of the 111 hand-assisted donor nephrectomies the resident was surgeon in 47%. Operative time proved a reliable and sensitive measure of surgeon experience. Increasing laparoscopic experience, as measured by several parameters, was associated with decreasing operative time (each p <0.02). Measurable improvements in laparoscopic skill were realized after participating in 13 (p = 0.007) or serving as surgeon in as few as 6 (p = 0.02) hand-assisted donor nephrectomies. Conversion (2%) and intraoperative complication rates (3%) were low. CONCLUSIONS: Skills for hand-assisted laparoscopic donor nephrectomy can be safely taught in the context of a urology training program independent of resident training level. We documented measurable improvements in laparoscopic skill as gauged by operative time. Our findings provide a basis by which expectations can be set for laparoscopic skill acquisition in the context of a residency program and for the laparoscopically naïve surgeon.

Clinical Competence↗

PubMed1988

Classical conditioning of beginning reading responses.

The present study describes the first demonstration that laboratory-controlled experimental procedures can lead to the successful acquisition and subsequent retention of classically conditioned beginning reading responses (CCBRRs) in children of both sexes and mean age of 4 yr. Anticipatory instructions combined with higher-order classical conditioning temporally arranged into a trace conditioning paradigm presented for 10 trials for each response to be learned led to beginning reading responses being successfully acquired by 20 children during 95% of the 2,220 total acquisition learning trials and subsequently correctly recalled on 114 of the 222 retention test trials. Findings support the view that perhaps the relatively sudden and sustained acquisition learning curves for reading responses on the second-signalling-system level of behavior in the present study may be quite different from the relatively slow and incremental learning curves usually obtained in classical conditioning of the autonomic type which occur on the first-signalling-system level.

Age Factors↗

PubMed2001

Objective laparoscopic skills assessments of surgical residents using Hidden Markov Models based on haptic information and tool/tissue interactions.

UNLABELLED: Laparoscopic surgical skills evaluation of surgery residents is usually a subjective process, carried out in the operating room by senior surgeons. By its nature, this process is performed using fuzzy criteria. The objective of the current study was to develop and assess an objective laparoscopic surgical skill scale using Hidden Markov Models (HMM) based on haptic information, tool/tissue interactions and visual task decomposition. METHODS: Eight subjects (six surgical trainees: first year surgical residents 2 x R1, third year surgical residents 2 x R3 fifth year surgical residents 2 x R5; and two expert laparoscopic surgeons: 2 x ES) performed laparoscopic cholecystectomy following a specific 7 steps protocol on a pig. An instrumented laparoscopic grasper equipped with a three-axis force/torque sensor located at the proximal end with an additional force sensor located on the handle, was used to measure the forces and torques. The hand/tool interface force/torque data was synchronized with a video of the tool operative maneuvers. A synthesis of frame-by-frame video analysis was used to define 14 different types of tool/tissue interactions, each one associated with unique force/torque (F/T) signatures. HMMs were developed for each subject representing the surgical skills by defining the various tool/tissue interactions as states and the associated F/T signatures as observations. The statistical distance between the HMMs representing residents at different levels of their training and the HMMs of expert surgeons were calculated in order to generate a learning curve of selected steps during laparoscopic cholecystectomy. RESULTS: Comparison of HMM's between groups showed significant differences between all skill levels, supporting the objective definition of a learning curve. The major differences between skill levels were: (i) magnitudes of F/T applied (ii) types of tool/tissue interactions used and the transition between them and (iii) time intervals spent in each tool/tissue interaction and the overall completion time. The objective HMM analysis showed that the greatest difference in performance was between R1 and R3 groups and then decreased as the level of expertise increased, suggesting that significant laparoscopic surgical capability develops between the first and the third years of their residency training. The power of the methodology using HMM for objective surgical skill assessment arises from the fact that it compiles enormous amount of data regarding different aspects of surgical skill into a very compact model that can be translated into a single number representing the distance from expert performance. Moreover, the methodology is not limited to in-vivo condition as demonstrated in the current study. It can be extended to other modalities such as measuring performance in surgical simulators and robotic systems.

Animals↗

PubMed1998

Review of percutaneous tracheostomy.

The purpose of this study is to assess the safety and efficacy of the four known methods of percutaneous tracheostomy. Perioperative, postoperative, and late complication rates were generated for each method after a complete literature review identified 1684 percutaneous tracheostomy patients reported in 40 series. Two methods, the Toye and the guide wire dilator forceps (GWDF) methods, have been the subject of few investigations. Two other methods have been extensively studied. A high perioperative complication rate was calculated for the Rapitrac method, whereas percutaneous dilational tracheostomy (PDT) has complication rates similar to those reported for standard operative tracheostomy. A retrospective review of 22 patients who underwent PDT at a local community hospital confirmed a "learning curve" for this technique that had been previously suggested. Review of the literature suggests that PDT can be safe and cost-effective for selected patients, but a learning curve for this technique exists that dictates caution, experience, and preparation on the part of any surgeon who wishes to add percutaneous tracheostomy to his or her repertoire.

Clinical Competence↗

PubMed2004

Comparison of Gas-less laparoscopy-assisted surgery, hand-assisted laparoscopic surgery and pure laparoscopic surgery for radical nephrectomy.

BACKGROUND: We report our experience with Gas-less laparoscopy-assisted surgery (Gas-less LAS), hand-assisted laparoscopic surgery (HALS) and pure laparoscopic surgery (LS) for renal carcinoma and compare the characteristics and usefulness of these methods. METHODS: Seventeen, 14 and 16 patients were subjected to Gas-less LAS, HALS and LS, respectively. The study started with Gas-less LAS and then gradually shifted to HALS and LS. We evaluated the operative and postoperative parameters for each group. The learning curve effect was evaluated based on data from the first 10 cases of each group, which were operated on by the same surgeon and operation team. RESULTS: The learning curve of operation times in the LS group demonstrated that the operation time for this procedure is acceptable even in early-stage cases. Differences in mean operative time between the three surgical groups, excluding the conversion cases, were not statistically significant; however, there was a significant difference in blood loss volume between the groups (P </= 0.001). Operation time tended to be shorter in Gas-less LAS and the frequency of parental analgesia administration tended to be reduced in the LS group when compared to the other two groups. Of the total 47 patients treated, two cases were converted to open surgery. The major postoperative complication was one case of brain infarction in the HALS group. One patient in the LS group developed a lung metastasis 11 months after the operation. CONCLUSION: As minimally invasive operative techniques, these three methods do not differ significantly in terms of surgical outcome; however, LS tended to be slightly superior in terms of postoperative pain control and cosmetic appearance.

Carcinoma, Renal Cell↗

PubMed2001

Adult-to-adult living donor liver transplantation using right-lobe grafts: results and lessons learned from a single-center experience.

Living donor liver transplantation (LDLT) for adults is now a practical alternative to cadaveric liver transplantation. Use of right-lobe grafts has become the preferred donor procedure. Because of the complexity of this operation, a learning curve is to be expected. We report the outcome of our first 41 LDLTs at the University of Colorado Health Sciences Center (Denver, CO). We also discuss the lessons learned and the resultant modifications in the procedure that evolved during our series. Patient records were retrospectively reviewed between August 1997 and February 2001 for the following end points: recipient survival, graft survival, and donor and recipient complications. Thirty-eight of 41 living donor liver transplant recipients (93%) are alive and well postoperatively with a mean follow-up of 9.6 months. Four patients required retransplantation secondary to technical problems (9.8%); all 4 patients were in our initial 11 cases. Modification of the donor liver plane of transection resulted in venous outflow improvement. Also, biliary management was modified during the series. Donor complications are listed; all 41 donors have returned to normal pretransplantation activity. Our results indicate that LDLT can be performed safely with excellent donor and recipient outcomes. Dissemination of our experience can help shorten the learning curve for other institutions.

Adult↗

PubMed2002

Controlled trial of the introduction of a robotic camera assistant (EndoAssist) for laparoscopic cholecystectomy.

BACKGROUND: The role of the human camera holder during laparoscopic surgery keeps valuable personnel from other duties. EndoAssist is a robotic camera-holding device controlled by the operator's head movements. This study assesses its introduction into clinical practice. METHOD: Ninety-three patients undergoing laparoscopic cholecystectomy were randomized to have either the robotic (40) or a human (46) assistant. Seven patients converted to open operation were excluded. Six surgeons were evaluated. Operating time and subjective assessments were recorded. Learning curves were constructed. RESULTS: The mean operating time was less using the robotic assistant (66 min) than with human assistance (74 min) (p < 0.05, two-tailed t-test). The learning curves for operating time showed that within three operations surgeons were trained in using the robot. The device was safe in use. CONCLUSION: The EndoAssist operating device is a significant asset in laparoscopic surgery and a suitable substitute for a human assistant. Surgeons became competent in the use of the robot within three operations. The robot offers stability and good control of the television image in laparoscopic surgery.

Adolescent↗

PubMed1998

Retroperitoneoscopy: experience with 200 cases.

PURPOSE: A retroperitoneal access is commonly used for open urological procedures. Since the introduction of the balloon dissecting technique by Gaur this anatomical route has also been used for laparoscopic surgery. We present our experience with retroperitoneoscopy in 200 cases. MATERIALS AND METHODS: From December 1992 to October 1997 a total of 200 retroperitoneoscopic procedures were performed in 197 patients 4 to 82 years old, comprising 78 nephrectomies, 50 renal cyst resections, 14 nephropexies, 11 ureterolyses, 8 retroperitoneal lymph node dissections, 8 renal biopsies, 6 adrenalectomies, 6 heminephrectomies, 6 pyeloplasties, 5 ureterolithotomies, 6 ureterocutaneostomies and 2 others. Of the patients 38 (19%) and 22 (11%) had undergone previous abdominal surgery, and kidney and ureter operations, respectively. Dissection of the retroperitoneal space was enabled by the use of a balloon catheter in 14, balloon trocar system in 93 and finger dissection technique in 93 cases. RESULTS: We classified 76 procedures (38%) as simple (renal biopsy, renal cyst resections, ureterocutaneostomy), 102 (51%) as difficult (adrenalectomy, nephrectomy, nephropexy) and 22 (11%) as very difficult (pyeloplasty, heminephrectomy, lymphadenectomy). There was a significant learning curve during the first 50 cases reflected by longer operating time, and higher complication, conversion to open surgery and open reintervention rates (14, 10 and 6%, respectively). In addition to the learning curve, mean operating time depended on the difficulty of the procedure, averaging 45 to 100 minutes for a simple, 95 to 185 for a difficult and 185 to 240 for a very difficult retroperitoneoscopy. In the last 50 cases the complication, conversion and reintervention rates (2, 4 and 2%, respectively) were acceptable for routine clinical application. CONCLUSIONS: After experience with more than 200 cases of retroperitoneoscopy the access technique has been significantly simplified. The procedure is standardized, safe and reproducible.

Adolescent↗

PubMed2005

Bile duct injuries associated with laparoscopic and open cholecystectomy: an 11-year experience in one institute.

PURPOSE: Bile duct injury (BDI) represents the most serious complication of laparoscopic cholecystectomy (LC). The aim of this retrospective single-institution study was to evaluate the real incidence of BDI during laparoscopic and open cholecystectomy (OC) in a tertiary academic center in Athens, Greece. METHODS: Between January 1991 and December 2001, 3637 patients underwent cholecystectomy in our department; as LC in 2079 patients (LC group) and as OC in 1558 patients (OC group). All the LCs were performed or supervised by five staff surgeons and all the OCs were performed or supervised by another five staff surgeons. RESULTS: There were 13 BDIs associated with LC (0.62%) and 6 associated with OC (0.38%) (P = 0.317). There was one death associated with BDI after LC. Only two (15.4%) of the BDIs associated with LC occurred within the proposed learning curve limit of 50 LCs per individual surgeon. CONCLUSION: Laparoscopic cholecystectomy is safe and is not associated with a higher incidence of BDI than OC. Moreover, we did not find that the learning curve for LC affected BDI occurrence.

Adult↗

PubMed2005

[Robots in general surgery: present and future].

Robotic surgery is an emerging technology. We began to use this technique in 2000, after it was approved by the Food and Drug Administration. Our preliminary experience was satisfactory. We report 4 years' experience of using this technique in our institution. Between August 2000 and December 2004, 399 patients underwent robotic surgery using the Da Vinci system. We performed 110 gastric bypass procedures, 30 Lap band, 59 Heller myotomies, 12 Nissen fundoplications, 6 epiphrenic diverticula, 18 total esophagectomies, 3 esophageal leiomyoma resections, 1 pyloroplasty, 2 gastrojejunostomies, 2 transduodenal sphincteroplasties, 10 adrenalectomies and 145 living-related donor nephrectomies. Operating times for fundoplications and Lap band were longer. After the learning curve, the operating times and morbidity of the remaining procedures were considerably reduced. Robot-assisted surgery allows advanced laparoscopic procedures to be performed with enhanced results given that it reduces the learning curve as measured by operating time and morbidity.

Bariatrics↗

PubMed2004

Preliminary report of multi degrees of freedom forceps for endoscopic surgery.

Laparoscopic suturing requires more complex techniques than conventional open surgery, because of the limited degrees of freedom of endoscopic devices. The prototype multi degrees of freedom forceps was developed with a concept of a flexibility that frees us from the restriction on suturing during endoscopic surgery. It was designed for a needle holder. We calculated the movement of the forceps' distal joint at the time of horizontal suturing. The learning curve was also investigated for ten surgeons. The device was clinically applied in several surgeries. We could perform suturing freely using this prototype forceps at any point and in any directions. The learning curve had its peak within five training sessions, and may be mastered during about ten training sessions. All clinical applications were successfully achieved. With the increased degree of freedom for forceps, the operability for endoscopic surgery was improved.

Analysis of Variance↗