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Results for “Learning Curve”

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At least 595 records · Page 33Linked to original sources

PubMed2002

Flexible endorectal ultrasound for predicting pathologic stage of rectal cancers.

BACKGROUND: Endorectal ultrasound (ERUS) is an accurate method for preoperative staging of rectal cancers. Most often, a rigid 360-degree rotating probe is used. We studied whether flexible probes could attain equivalent accuracy for bowel wall penetration. METHODS: Forty-five patients were prospectively evaluated with flexible devices. Results were compared with 20 rigid and 10 flexible probe studies. To assess learning curves, we used logistic regression analysis and coefficients of correlation on accuracy data to compare ERUS accuracy with the number of examinations. RESULTS: Level of invasion was correct in 49%. Nodal examinations were correct in 78%. Learning curves leveled out at 100 examinations with 87% accuracy for the rigid probe (R = 0.46) and 77% for the flexible devices (R = 0.31). CONCLUSIONS: The coefficient of correlation for each method portends a more reliable learning curve for the rigid devices. Flexible devices were less accurate for level of invasion than the literature reported for rigid devices.

Adenocarcinoma↗

PubMed2004

Assessing the validity of the endoscopic shunt insertion trial: did surgical experience affect the results?

OBJECT: Most surgical procedures are associated with a learning curve in which the success rate is lower early in the experience before mistakes have been identified and modifications made to the procedure. Negative results obtained early in a trial's learning curve may be a matter of timing rather than a reflection of the procedure's effectiveness. The recently published results of the Endoscopic Shunt Insertion Trial (ESIT) represent the notion that endoscopically placed shunts were no more likely to survive than conventionally placed shunts. This negative result may be due to inexperience in performing endoscopic surgeries. METHODS: . Surgical experience was assessed in two ways. Shunt survival rates were compared between cases treated endoscopically in the 1st and last years of the ESIT. The effect of center volume was evaluated using a Cox proportional hazard model in which the following variables were analyzed: age at registration, the diagnosis of myelomeningocele, head size, method of shunt placement (endoscopic compared with conventional), and center volume. There was no difference in survival (endurance) of the shunt between patients enrolled in the 1st and last years (log rank = 0.08, p = 0.77). Likewise, no variable in the Cox multivariate model, including center volume, was a significant factor in predicting shunt survival. CONCLUSIONS: The primary result of the ESIT was found to be internally valid. The fact that endoscopic shunt placement did not benefit patients evaluated in the study was not due to early timing of the trial. Any learning curve among the participating surgeons did not adversely affect the results.

Cerebrospinal Fluid Shunts↗

PubMed1990

The left brain determines the degree of left-handedness.

The contribution of right- and left-hand skills to left-handedness was studied in 42 left-handed male subjects. Hand preference was assessed by the Edinburgh Handedness Inventory. Hand skill was assessed by a peg-moving task; 10 trials were given to each hand. Peg-moving times decreased linearly with each trial (visuomotor learning). Both hands exhibited equal learning capacities. The learning curves were the same for the left-hands of left-handers with and without familial sinistrality (FS). The right-hand of left-handers with FS was found to be slower than that without FS. The right- and left-hand skills and their learning curves were about the same in left-handers with right-hand writing, exhibiting no difference from the left-hand skill and learning curve of left-handers with left-hand writing. Right-hand skill decreased linearly as left-hand preference increased from -40 to -100; left-hand skill was not related to hand preference. Right-minus left (R-L) time for peg moving increased linearly with hand preference from -40 to -100. R-L time for peg moving linearly decreased as the right-hand skill increased; the left-hand skill was not associated with R-L time for peg moving. It was concluded that the right hand (left brain) determines left-handedness; the neural structures only on the left side exhibit pronounced plastic changes to genetic and environmental influences in left-handers.

Adult↗

PubMed2004

Robotic pyeloplasty: technique and results.

The da Vinci robotic system can be used to perform dismembered and nondismembered pyeloplasty techniques effectively. Robotics not only seems to improve dexterity and surgical precision but also provides an ergonomic surgical environment for a surgeon performing complex reconstructive procedures such as pyeloplasty. Although performance-enhancing features of the da Vinci robot seem to decrease the difficulty of intracorporeal suturing, a learning curve also exists for telerobotic procedures. This learning curve may decrease as experience with telerobotics increases and as advances in technology are introduced. Presently, the interaction between the primary and assistant surgeon seems crucial to the success of the procedure. Although the early clinical experience with robotic pyeloplasty is favorable, continuing clinical evaluation and careful follow-up are required to determine if the procedure is as efficacious in the long run as open pyeloplasty and laparoscopic pyeloplasty.

Follow-Up Studies↗

PubMed1997

Role of an operative score in mitral reconstruction in dominantly stenotic lesions.

OBJECTIVE: The role of an operative score in selection and results of mitral valve reconstruction in dominantly stenotic mitral lesions was assessed. METHODS: A total of 136 patients consecutively underwent reconstruction for rheumatic mitral stenosis with or without regurgitation from December 1989 through December 1994. Mitral valve structure was scored for cuspal pliability and thickness, cuspal area loss, chordal length, papillary muscle length, annular dilatation and degree of associated regurgitation and calcification. A score of 0 indicated normal valve while a score of 24 indicated a grossly deformed valve. Age, sex, functional class, cardiac rhythm, mitral valve orifice area, left ventricular and left atrial dimensions, transmitral gradients, pulmonary artery pressures and thoroughness of repair were evaluated. RESULTS: Mitral valve architecture was disorganised moderately in 50 (37%) and severely in 69 (52%) patients. Extent of thoroughness in different operative techniques correlated with good (n = 30) or adequate (n = 60) outcome. Mean mitral valve orifice area increased from 0.77 +/- 0.2 to 2.56 +/- 0.6 cm2, peak gradient dropped from 20.3 +/- 6.2 to 8.6 +/- 3.5 torr, mean gradient from 13.5 +/- 4.9 to 4.76 +/- 2.2 torr and end-diastolic gradient from 10.1 +/- 5.0 to 3.2 +/- 1.9 torr. Lack of recognition of anatomical details and of all necessary componental measures constituted the learning curve of different operators. CONCLUSIONS: Recurrent disease, learning curve, inadequate repair and higher operative mitral valve score were the factors for poorer results in the intermediate term follow-up to 64 months. Thoroughness of repair was the most important correlate of outcome and indicative of expertise.

Adolescent↗

PubMed2005

Mini-incision resurfacing arthroplasty of hip through the posterior approach.

UNLABELLED: The success of metal-on-metal hip resurfacing in the medium term in young and active patients is becoming evident. The procedure now can be done using a minimal approach developed by the senior author using a single posterior incision. This mini-incision resurfacing arthroplasty of the hip has made resurfacing more attractive to surgeons and patients. But does a mini incision approach allow reliable component placement? The results of 232 consecutive Birmingham Hip Resurfacings done using this approach between January and December 2004 are presented. Mean incision length was 11.8 cm. Seventy-seven percent of the incisions were between 9 and 12 cm long. Body mass index of the patients studied ranged from 17.6 to 46.7. Comparing the traditional approach with the mini-incision resurfacing arthroplasty of hip did not show a difference between the two groups in terms of operating time. The mean hospital stay was reduced by a day in the mini-incision group. The mean inclination of the acetabular components was within the target range in the two groups. Patient feedback shows that reduced postoperative pain, faster recovery rate, and better cosmesis make the mini-incision approach very popular. Although the mini incision is indeed appealing, it has a steep learning curve. In the early phase of the learning curve, care should be taken to avoid suboptimal component placement, which has the potential to affect long-term outcome adversely. LEVEL OF EVIDENCE: Therapeutic study, Level III (retrospective comparative study). See the Guidelines for Authors for a complete description of levels of evidence.

Arthroplasty, Replacement, Hip↗

PubMed1997

[Assessment of a new light guide (Trachlight) for tracheal intubation].

OBJECTIVE: To assess the learning curve of a new lighwand device, Trachlight (Laerdal), for blind orotracheal intubation in patients without foreseen difficulty in airway management. STUDY DESIGN: Open, prospective, clinical study. USERS: Twelve persons practicing anaesthesia (specialists, trainees, nurses) underwent videotape learning and manikin training with ten successful intubation manoeuvres required with the device. METHODS: Each person had to carry out a tracheal intubation in ten consecutive patients undergoing scheduled surgery and without history or clinical sign of difficults airway management. RESULTS: One hundred and twenty patients were included. The overall success rate with the Trachlight was 87%. An easy learning curve was obtained as demonstrated by the low failure rate in the first three patients, and by the success rate on the first or second attempt in the last four patients. There was no significant difference in failure rate with or without muscle relaxation (10 vs 20%, NS). Finally, all failures with the Trachlight were followed by successful intubation using direct laryngoscopy, and no traumatic complications were recorded with the device. CONCLUSION: Trachlight is a new lightwand device enabling blind tracheal intubation with a easy learning curve in patients without difficulty in airway management, even for non-selected operators.

Adult↗

PubMed2002

Surgeon experience and patient comfort during clear corneal phacoemulsification under topical local anesthesia.

PURPOSE: To evaluate patient comfort during topical anesthesia clear corneal phacoemulsification surgery performed by a surgeon in the learning curve or by an experienced surgeon. SETTING: Royal Alexandra Hospital, Paisley, Scotland, United Kingdom. METHODS: This study comprised 46 consecutive patients having phacoemulsification under topical anesthesia of proparacaine 0.5% (Proxymetacaine. Surgery was performed by a surgeon during his learning curve (n = 20) or by an experienced surgeon (n = 26). No sedation or intracameral anesthesia was used in either group. All patients had clear corneal phacoemulsification with foldable acrylic posterior chamber intraocular lens implantation. Each patient's subjective experience of overall pain perioperatively (period immediately surrounding and during surgery) and worst pain perceived during surgery was measured immediately after surgery using a 10-point visual analog scale. RESULTS: There was no significant difference in patient-reported pain scores for overall pain perioperatively (P =.47, Wilcoxon rank sum test) and the worst pain perceived during surgery (P =.32, Wilcoxon rank sum test). CONCLUSIONS: Topical anesthesia with proparacaine provided similar and reasonable analgesic effects in patients having surgery by a surgeon in the learning curve and those having surgery by an experienced surgeon. The discomfort perceived during surgery performed by an experienced surgeon was less, although not statistically significantly different.

Aged↗

PubMed2004

Robot-assisted laparoscopic Roux-en-Y gastric bypass.

BACKGROUND: Robotic surgery promises to extend the capabilities of the minimally invasive surgeon. The aim of this study was to examine the feasibility of robotic surgery in the setting of laparoscopic gastric bypass. METHODS: The Zeus robotic surgical system was used in 50 laparoscopic gastric bypass procedures. The learning curve was staged to add complexity to the robotic tasks as experience grew. Robotic setup time, robotic operative time, total operative time, and operative outcomes were tracked prospectively. RESULTS: We observed a significant decrease in the robotic setup time. Our robotic learning curve demonstrated decreased operative time, even as more complex tasks were accomplished. Total operative time also decreased significantly over the series. There were no complications in our series that could be attributed to the robotic technique. CONCLUSIONS: Robot-assisted laparoscopic Roux-en-Y gastric bypass is safe. The steadiness and extra degrees of freedom of surgical robotic systems may improve the accuracy of laparoscopic tasks. The learning curve for robot-assisted laparoscopic Roux-en-Y gastric bypass is significant but manageable.

Adult↗

PubMed1998

A 5-year audit of trainees experience and outcomes with two-stage hypospadias surgery.

The results of a 5-year audit of trainee plastic surgeons' experience and outcomes with two-stage hypospadias surgery are presented. Between June 1991 and October 1996, 87 patients had at least one of their operations performed by trainees; 79 patients had completed their surgery and were available for study. All patients underwent two-stage hypospadias correction; median duration of follow-up was 707 days. 69.5% of patients required correction of glans tilt and/or chordee correction; a small meatus was present in 62%. Trainees performed 73.2% of the first stage surgery (23.2% supervised by the consultant and 50% as most senior surgeon). The total complication rate for the first stage was 6.1%; the complications were: residual chordee and/or insufficient skin graft take (4 cases) and haematoma (1 case). Trainees performed 58.2% of the second stage surgery (24.1% supervised by the consultant and 34.2% as most senior surgeon). The fistula rate for the trainee stage 2 cases was 15.2% and the stricture rate 4.3%. All fistulae and strictures were successfully treated by one additional procedure. Complications rates for the first stage were similar between grades; consultant 4.5%; supervised trainee 5.3% and unsupervised trainee 7.3%. However, unsupervised trainees had a much higher complication rate for the second stage: 29.6%, versus consultant 3.0% and supervised trainee 5.3%. These complication rates represent the cumulative learning curve of 17 trainee surgeons. Outcomes for two individual trainees after the same number of cases (47) were studied further. These trainees had the highest and lowest complication rates for the procedure; 24% versus 9%. These figures might better reflect the range of the learning curve of this procedure. A major difference between these two trainees was the time taken to accrue 47 cases; 15 months versus 25. In the former case this concentration of training was felt to be beneficial. Further analysis of one trainee's results suggested that complications occur early in the learning curve and with appropriate supervision acceptable complication rates can be achieved.

Adolescent↗

PubMed2002

Validation of sentinel node mapping in patients with colon cancer.

BACKGROUND: Sentinel lymph node (SLN) mapping techniques have been validated in breast cancer and melanoma. This study summarizes our experience with SLN mapping for colon cancer. METHODS: Fifty-five patients with colon cancer underwent intraoperative SLN mapping. One mL of 1% isosulfan blue was injected subserosally around the tumor. The first nodes highlighted with blue were identified as the SLNs. SLNs underwent multiple sectioning and immunohistochemical staining for cytokeratin. The overall learning curve was calculated. RESULTS: Lymphatic mapping adequately identified at least 1 SLN in 45 patients (82%). SLNs adequately predicted regional status in 44 of 45 (98%) cases. In 9 of 45 cases (20%), the SLNs were the only sites of metastases. Among the 14 cases that were SLN positive, 6 of 55 patients (11%) were positive only by immunohistochemistry. Of the 31 cases with negative SLNs, 1 case had a 3.5-mm pericolonic tumor-replaced non-SLN (3% false-negative rate). The overall learning curve stabilized after five cases. CONCLUSIONS: Intraoperative SLN mapping is a feasible technique, with a quick learning curve, and had a reasonable SLN identification rate. Negative SLNs accurately predict the status of non-SLNs 97% of the time. Eleven percent of patients were upstaged by demonstration of micrometastases and may benefit from adjuvant chemotherapy.

Adenocarcinoma↗

PubMed1998

Preliminary technique of laparoscopic extraperitoneal infrarenal paraaortic lymphadenectomy in the porcine model.

We developed an extraperitoneal approach to laparoscopic infrarenal paraaortic lymphadenectomy in the porcine model, with the ultimate aim of shortening the long learning curve of this procedure in humans. Surgery was performed on four females pigs with three 10-mm cannulas placed along the midaxillary line in prone position. The first and second pigs underwent subsequent laparotomy to evaluate the adequacy of lymph node dissection and complications. In all four animals, complete infrarenal paraaortic lymphadenectomy was successful, retrieving between 6 and 11 lymph nodes (average 9). Laparotomy in the first two animals confirmed adequate lymphadenectomy. No complications occurred. Operating time was shortened dramatically with each procedure (180, 120, 50, 40 min). In the porcine model this approach provides excellent exposure to the entire paraaortic lymphatic chain, is safe, and has a remarkably short learning curve. Development of a similar technique in humans may have significant advantages, including short learning curve, feasibility in obese patients and those with peritoneal adhesions, decreased adhesion formation, and reduced bowel complications associated with postoperative adjuvant irradiation. Further studies are indicated.

Animals↗

PubMed2004

Simplifying the vertical reduction mammaplasty.

The vertical reduction mammaplasty is an evolving technique. Its proponents report significantly decreased scarring, better breast shape, and more stable results compared with the standard inverted-T method, but the learning curve is long and cosmetic outcomes can be inconsistent. Many surgeons have experimented with the vertical closure before returning to methods more familiar to them. The authors present their modifications to the vertical reduction mammaplasty. Their changes simplify the preoperative markings and the intraoperative technique to shorten the learning curve while maintaining reliable aesthetic results. With the patient standing, only four preoperative marks are made: (1) the inframammary fold; (2) the breast axis; (3) the apex of the new nipple-areola complex; and (4) the medial and lateral limbs of the vertical incision. In the operating room, a medial or a superomedial pedicle is developed. Excess breast skin is resected with the inferior and lateral parenchyma as a C-shaped wedge. The lateral skin-adipose flap is redraped inferomedially and sutured to the chest wall. The inferior aspect of the breast is aggressively debulked and a gathering subcuticular stitch is started 2 cm below the nadir of the nipple-areola complex. Finally, a 38-mm to 42-mm nipple-areola complex marker is used to create a circular defect that is offset 0.5 cm medial to the vertical axis of the breast. In their series, 56 patients were treated and no major complications were noted. The median follow-up period was 17 months. The average reduction was 554.5 g per breast; however, the reduction was greater than 1000 g per breast in eight patients. The authors found that (1) chest wall anchoring improves lateral contour and minimizes axillary fullness; (2) aggressive debulking inferiorly avoids the persistent inferior bulge; and (3) starting the subcuticular gathering suture 2 cm below the nipple-areola complex followed by placement of a nipple-areola complex marker at the conclusion of the case prevents lateral deviation and corrects the nipple-areola complex teardrop deformity. These innovations accelerate the learning curve by simplifying the preoperative markings and lead to more consistent postoperative results and an improved cosmetic outcome. In conclusion, these modifications yield a simple, easily learned vertical reduction mammaplasty with aesthetically reliable results.

Adolescent↗

PubMed2006

An evidence-based virtual reality training program for novice laparoscopic surgeons.

OBJECTIVE: To develop an evidence-based virtual reality laparoscopic training curriculum for novice laparoscopic surgeons to achieve a proficient level of skill prior to participating in live cases. SUMMARY BACKGROUND DATA: Technical skills for laparoscopic surgery must be acquired within a competency-based curriculum that begins in the surgical skills laboratory. Implementation of this program necessitates the definition of the validity, learning curves and proficiency criteria on the training tool. METHODS: The study recruited 40 surgeons, classified into experienced (performed >100 laparoscopic cholecystectomies) or novice groups (<10 laparoscopic cholecystectomies). Ten novices and 10 experienced surgeons were tested on basic tasks, and 11 novices and 9 experienced surgeons on a procedural module for dissection of Calot triangle. Performance of the 2 groups was assessed using time, error, and economy of movement parameters. RESULTS: All basic tasks demonstrated construct validity (Mann-Whitney U test, P < 0.05), and learning curves for novices plateaued at a median of 7 repetitions (Friedman's test, P < 0.05). Expert surgeons demonstrated a learning rate at a median of 2 repetitions (P < 0.05). Performance on the dissection module demonstrated significant differences between experts and novices (P < 0.002); learning curves for novice subjects plateaued at the fourth repetition (P < 0.05). Expert benchmark criteria were defined for validated parameters on each task. CONCLUSION: A competency-based training curriculum for novice laparoscopic surgeons has been defined. This can serve to ensure that junior trainees have acquired prerequisite levels of skill prior to entering the operating room, and put them directly into practice.

Benchmarking↗

PubMed2004

Minimally invasive Oxford unicompartmental knee arthroplasty: functional results at 1 year and the effect of surgical inexperience.

Oxford medial unicompartmental arthroplasty (UCA) is now routinely performed through a short incision without dislocation of the patella. We present the 1 year results of the first 104 knees operated in Oxford using this technique and the learning curve associated with it. The patient's average age at surgery was 68 years. The average American Knee Society 'knee score' improved from 37 to 94 points and the average 'functional score' from 50 to 92 points. Average maximum flexion improved from 117 to 131 degrees. The average knee score during a surgeon's first 10 cases was 88 points, which was significantly less (P<0.03) than the score achieved for subsequent cases after the first 10 (95 points). These data suggest for the first time that a learning curve exists with worse results being achieved during a surgeon's first 10 cases. However, the results during the learning curve are still similar to that achieved after total knee arthroplasty.

Aged↗

PubMed1997

Shift in the performance of 24-month-old Wistar rats in the Morris water escape task: a comparison across 36 experiments.

Spatial discrimination learning in aged rats serves as an animal model of cognitive aging. We assessed the replicability of spatial discrimination performance in the standard Morris water escape task. To this end the learning curves and the performance in a probe trial of 24-month-old outbred Wistar (HsdWin:Wu) control rats from 36 experiments were compared. These experiments had been performed at our laboratory under strictly controlled conditions over a period of 71 weeks. There was a very high variability in the learning curves between experiments. The initial performance level, i.e. the performance during the first session, did not change systematically across the 36 experiments. In contrast, the final performance level, i.e. the level reached in the fifth training session, decreased over the 71 week period, when the platform escape latency and the distance swam to reach the platform, measured as number of line crossings, were considered. In the last experiments of the series, learning curves were no longer seen: the rats did not improve their performance across the acquisition sessions. By contrast, the swimming speed and, in the probe trial, the bias for the quadrant where the platform had been positioned during training, did not change. This indicates that a decrease across experiments occurred predominantly with respect to spatial orientation performance, whereas the motor performance appeared to be unchanged. Explanations for this observation, such as differences in viability between shipments and the possible occurrence of genetic drift, are discussed.

Aging↗

PubMedDate not supplied

Perioperative complications of the Agility total ankle replacement in 50 initial, consecutive cases.

Although functional and clinical outcomes after total ankle arthroplasty have been promising, a steep learning curve has been recognized. In addition, the performance of concomitant hindfoot realignment procedures is controversial. The purpose of this study was to report on a single surgeon's experience with the first 50 total ankle arthroplasty procedures. We wanted to define the characteristics of the learning curve and whether the rate of complications was increased in patients who required complex reconstruction for preexistent foot and ankle deformities. This was a retrospective study of 50 cases with an average follow-up of 24.2 months. The patient population consisted of 18 men and 30 women with an average age of 57.6 years. Twenty-six percent of the cases had concomitant bony realignment procedures, while 20% had prior history of major hindfoot corrective procedures. There were 19 cases with intraoperative malleolar fractures, 12 cases that exhibited some degree of malalignment, and 6 cases of syndesmotic nonunion, and 8 ankles required early component revision. Minor wound complications that resolved with local wound care occurred in 9 cases, while 1 patient had a major wound complication requiring flap coverage. Each of these complications, other than wound complications, decreased with the surgeon's experience. Our results also indicate that the performance of major realignment procedures at the same time of implant arthroplasty is not associated with an increased incidence of complications. The results of this study suggest that total ankle arthroplasty is associated with a learning curve. Perioperative complications may potentially decrease with surgeon experience.

Adult↗

PubMed2005

Virtual reality colonoscopy simulation: a compulsory practice for the future colonoscopist?

BACKGROUND AND STUDY AIM: As for any manual procedure, the learning curves for medical interventions can have undesirable phases, occurring mostly in the early experience of applying a technique. There have been impressive advances in endoscopic procedures during recent years, and there is an emerging trend that the number of procedures is increasing in parallel with these. In addition, the introduction of screening programs for colorectal cancer will also increase the numbers of procedures needed. Recent developments in medical simulation seem promising with regard to the possibility of "training out" undesirable parts of the learning curve outside the operating room. The aim of this study was to investigate whether the use of the AccuTouch flexible endoscopy simulator improves the early part of the learning curve in colonoscopy training. METHOD: 12 endoscopy trainees, 10 surgeons and two medical gastroenterologists, all with experience in gastroscopy but with no specific colonoscopy experience, were randomly assigned to either simulator training or to a control group. They all received the same theoretical study package and the training group practiced with the AccuTouch colonoscopy simulator until a predefined expert level of performance was reached. All trainees performed their first ten individual colonoscopies described in detail in a separate protocol. RESULTS: Trainees in the simulator-trained group performed significantly better (P=0.0011) and managed to reach the cecum in 52% of their cases (vs. 19% in the control group), and were 4.53 times more likely to succeed compared with the controls. Additionally, there was a significantly shorter procedure time and less patient discomfort in the hands of the simulator-trained group. CONCLUSION: Skills acquired using the AccuTouch simulator transfer well into the clinical colonoscopy environment. The results of this trial clearly support the plan to integrate simulator training into endoscopic education curricula.

Adult↗