SEARCH · PubMed Health

Results for “Learning Curve”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,081 records · Page 60Linked to original sources

PubMed1990

Current assessment of fetal losses as a direct consequence of chorionic villus sampling.

Chorionic villus sampling has been developed as a method of first trimester prenatal diagnosis. In order to evaluate this new approach, accurate risk figures for the procedure must be obtained. This has been difficult for a number of reasons, including establishment of baseline fetal loss rates in the first trimester, procedural "learning curves," and reporting biases. This review will discuss these problems and use data from the chorionic villus sampling program at the University of California, San Francisco, to illustrate difficulties in data interpretation.

Abortion, Spontaneous↗

PubMed1991

Conventional versus laparoscopic cholecystectomy and the randomized controlled trial. Cholecystectomy Study Group.

We considered using a randomized trial to assess the value of laparoscopic cholecystectomy in the treatment of symptomatic gallstones. The pros and cons for the timing of such a trial were in favour of not beginning the trial until surgeons learned to use the new procedure safely and effectively, and until key endpoints and outcome indices could be identified and assessed using valid measures. Instead an observational study was implemented to monitor the learning curve of surgeons as they mastered the laparoscopic equipment and procedures, and to assess the responses of the patients to the procedure. In the first 100 patients, the procedure proved to be as safe and feasible to use as conventional surgery, and there were strong benefits in terms of quicker recovery of the patients with less pain, discomfort, and a reduced length of hospital stay. The responses of the surgeons and the patients to the new procedure now place ethical constraints on the planning of a randomized controlled trial. Currently, comprehensive surveillance and monitoring of laparoscopic cholecystectomy is the only realistic method with which to assess the impact of this new technology in our clinic.

Adult↗

PubMed1995

Bile duct injury and bile leakage in laparoscopic cholecystectomy.

The introduction of laparoscopic cholecystectomy has been associated with an increased incidence of bile duct injury. This review presents the incidence of bile duct injury in reported series and examines the role of the learning curve and other contributing factors. There is good evidence to suggest that, with adequate training and experience, the incidence of biliary injury can be reduced to a level comparable to that of open cholecystectomy. Continued audit is required to ensure that the low complication rates achieved in selected centres with wide experience are reproduced by the surgical community in general.

Bile↗

PubMed1996

Incidence and nature of bile duct injuries following laparoscopic cholecystectomy: an audit of 5913 cases. West of Scotland Laparoscopic Cholecystectomy Audit Group.

The rapid introduction of laparoscopic cholecystectomy has been associated with an apparently increased incidence of bile duct injury which has provoked worldwide concern. The true incidence and mechanism of iatrogenic ductal injury during the development of this procedure remain unclear. To assess this, the introduction of laparoscopic cholecystectomy in the West of Scotland has been audited prospectively over a 5-year period. All cases of biliary ductal injury have been independently reviewed. Some 48 surgeons undertaking laparoscopic cholecystectomy in 19 hospitals submitted prospective data between September 1990 and September 1995. A total of 5913 laparoscopic cholecystectomies were attempted with 98.3 per cent completion of data collection. During this period 37 laparoscopic bile duct injuries occurred. The annual incidence peaked at 0.8 per cent and has fallen to 0.4 per cent in the final year of audit. Injuries occurred after a median personal experience of 51 (range 3-247) laparoscopic cholecystectomies in 22 surgeons. Major bile duct injuries occurred in 20 of 37 patients, giving an incidence of 0.3 per cent. Five mechanisms for laparoscopic ductal injury were identified, including tenting, confluence and diathermy injuries as well as the classical and variant classical types. Ductal injuries were discovered at operation in 18 patients with consequent repair giving a good clinical outcome in 17. Contributory factors (severe inflammation, aberrant anatomy and poor visualization) were present in only 13 of 37 cases. This audit suggests that, at least in the introductory period, laparoscopic cholecystectomy is associated with an overall bile duct injury rate higher than that reported previously after open cholecystectomy, although the incidence of major ductal injury is similar. The late downward trend in bile duct injury, however, suggests there may be a prolonged learning curve for this procedure. Improved understanding of the mechanism of injury may lead to yet further reductions in this complication.

Bile Ducts↗

PubMed2003

Assessment of the accuracy of transrectal ultrasonography in anorectal neoplasia.

BACKGROUND: Accurate preoperative staging of anorectal neoplasia is required to identify patients for whom local excision or adjuvant therapy may be appropriate. The objectives of this study were to review the accuracy of endoluminal transrectal ultrasonography (TRUS) in the staging of rectal cancers and to determine the learning curve before optimal staging accuracy can be achieved. METHODS: The results of all TRUS examinations for the assessment of anorectal neoplasia performed by two colorectal surgeons at two teaching hospitals of the University of Sydney from 1991 to 2001 were collected prospectively. RESULTS: Of the 433 patients examined by TRUS, 356 were included, of whom 263 (73.9 per cent) had nodal status assessed histologically. Of the 77 patients excluded, 50 had undergone radiotherapy before operation. TRUS achieved excellent accuracy when compared with histopathology reports using kappa statistics for standard Union Internacional Contra la Cancrum (UICC) staging (kappa = 0.89), tumour wall penetration (kappa = 0.70), lymph node detection (kappa = 0.66) and a proposed new staging system (kappa = 0.94). In addition, the increase in TRUS accuracy with operator experience demonstrates the need to perform 50 or more procedures before optimal accuracy is achieved. CONCLUSION: TRUS provides an appropriate investigation with which to select patients with T1 tumours for local excision, and patients with T3 or T4 tumours for preoperative radiotherapy. The relative inaccuracy of staging T2 tumours by TRUS has led to a proposed alternative ultrasonographic staging system.

Anus Neoplasms↗

PubMed2004

Hand-assisted laparoscopic live donor nephrectomy.

BACKGROUND: Hand-assisted laparoscopic donor nephrectomy (HLDN) may have advantages over laparoscopic donor nephrectomy, such as shorter learning curve, operation and warm ischaemia times. The aim of this study was to evaluate the feasibility and safety of HLDN. METHODS: Between January 2000 and October 2002, 50 consecutive HLDN procedures were performed through a low transverse abdominal incision, 23 right sided and 27 left sided. RESULTS: The median age of the donors was 44 years. No HLDN required conversion to an open procedure. The median operating time for HLDN was 153 min. The median warm ischaemia time was 3 (range 1.0-4.5) min and the median blood loss was 50 (range 20-500) ml in both left- and right-sided procedures. Eight patients suffered ten minor complications during their admission. The duration of hospital stay was 5 days for donors. Three recipients developed graft failure owing to acute rejection, renal vein thrombosis and ischaemic necrosis. CONCLUSION: Both left- and right-sided HLDN procedures were feasible and safe through a low transverse abdominal incision.

Adult↗

PubMed2004

Randomized clinical trial of hand-assisted laparoscopic versus open Roux-en-Y gastric bypass for the treatment of morbid obesity.

BACKGROUND: : Roux-en-Y gastric bypass (RYGBP) has increased in popularity since the introduction of the laparoscopic procedure, but this approach requires extensive surgical skill and the learning curve is steep. The present study examined the suitability of hand-assisted laparoscopy for RYGBP. METHODS: In a prospective trial, 50 patients (median age 38 years, body mass index 45 kg/m(2)) were randomized to either hand-assisted (n = 25) or open (n = 25) RYGBP. The hand-assisted device was introduced through a right subcostal incision. Laparoscopic staplers were also used in the open group, allowing a short upper midline incision. The gastrojejunostomy was made by means of a circular stapler and the Roux limb placed behind the colon and excluded stomach. RESULTS: The postoperative outcome, with respect to morphine consumption, complications, hospital stay (6 days) and weight loss, was similar in the two groups. The operating time was significantly longer in the hand-assisted group (150 versus 85 min; P < 0.001) but there was no conversion to open operation. One patient in the hand-assisted group was reoperated owing to leakage and one patient developed an incisional hernia after open RYGBP. CONCLUSION: The hand-assisted technique was feasible and allowed good working conditions in all patients. However, the postoperative outcome was excellent in both groups and there was no advantage to the hand-assisted technique.

Adult↗

PubMed2002

Clinical results for the training-phase roll-in patients in the Intracoil femoralpopliteal stent trial.

The purpose of this study was to report the results of the roll-in patients for the multicenter IntraCoil trial in the femoropopliteal arteries at 9-month follow-up. Ninety-three roll-in patients (mean age, 67.8 +/- 10.5 years; 62.4% male gender) constituted the learning phase for the 22 clinical sites. Obstructive femoropopliteal artery disease up to 15 cm was treated with stenting. Clinical patency was measured over a 9-month period by clinical and hemodynamic data as well as the Rutherford scale. Diabetes mellitus was present in 35.5%. Twenty-nine percent of lesions treated were occlusions. The mean reference diameter for treated lesions was 4.27 +/- 1.11 mm, while the mean lesion length was 3.83 +/- 3.69 cm. Acute angiographic success by operator evaluation was obtained in 98.9% of patients. Major complications occurred in 3.2%. No patient experienced abrupt or subacute closure. There were two reports of failure to deliver assigned stent. In both incidences, the stent was removed without surgical intervention. There were also three reports of stent misplacement (moving during delivery), one report of stent migration, one report of delivery system failure. At 30-day and 9-month follow-up of successfully treated patients, 100%/77.9% remained free of major adverse clinical events (MACE) and 100%/81.8% target lesion revascularization (TLR), respectively. At 9-month follow-up, ankle-brachial index increased from 0.66 +/- 0.22 to 0.83 +/- 0.20 while mean maximum walking time increased form 4.47 +/- 3.02 to 5.91 +/- 3.97 min. The use of the IntraCoil stent appears to have a short learning curve. Excellent clinical and hemodynamic patency is seen at 9 months. The randomized comparison trial comparing the IntraCoil to angioplasty is pending.

Aged↗

PubMed1988

Development and application of transseptal left heart catheterization.

The recent interest in transseptal left heart catheterization affords an opportunity to review the development and application of this procedure. This review briefly follows the history of right and left heart catheterization to the development of the transseptal procedure. A detailed description of the technique of transseptal catheterization is provided, as well as the indications and contraindications to its use. A learning curve is associated with this technique and is inversely related to the complication rate of the transseptal approach. Physicians working in high volume catheterization laboratories may gain the experience to safely perform transseptal left heart catheterization on carefully selected patients.

Cardiac Catheterization↗

PubMed1992

Coronary stenting: single institution experience with the initial 100 cases using the Palmaz-Schatz stent.

We studied 100 patients who had coronary implantation of Palmaz-Schatz stents in our institution from November 1989 until March 1991. A total of 126 standard and 6 short stents were implanted. The patients' mean age was 58 +/- 5 years, and 97 were males. The indications were lesions with high risk of restenosis (29 patients), restenosis (27 patients), suboptimal result of angioplasty (24 patients), dissection (16 patients), and recanalized chronic total occlusion (6 patients). In 17 patients a brachial cut-down approach was used. Stents were correctly placed in 98 patients. Stent related complications occurred in 9 patients: major ischemic complications in 7 patients (acute myocardial infarction in 2 patients, emergency bypass surgery in 3 patients and emergency angioplasty in 2 patients); in 3 of these patients there was a subacute closure of the stent and in 2 patients there were delivery problems. Vascular complications at the site of arterial puncture occurred in 3 patients (some patients had more than one complication). A learning curve was observed. There was a decrease in the complication rate with the higher number of patients treated: 28% for the first 50 patients and 6% for the last 50 patients. Clinical follow-up was available in all patients. Of the 92 patients eligible for follow-up (7 +/- 2 months), 69 patients were asymptomatic and 23 had recurrence of angina: 19 patients for stent restenosis and 4 patients for coronary artery disease progression. Follow-up angiogram was done in 79/92 (86%) patients: 21 had restenosis (27%).(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗

PubMed2006

Carotid stenting with distal protection in high surgical risk patients: the BEACH trial 30 day results.

BACKGROUND: The BEACH trial evaluated the outcomes of carotid artery stent placement with distal emboli protection, using the Carotid Wallstent and the FilterWire EX/EZ(TM), in patients at high surgical risk for carotid endarterectomy (CEA). METHODS: We enrolled 747 patients at high surgical risk for CEA due to prespecified anatomical criteria and/or medical comorbidities. The trial included both symptomatic (>50% carotid artery stenosis) as well as asymptomatic (>80% carotid artery stenosis) high surgical risk patients. Three groups of patients were included in the trial. The Roll-in (R) group (n = 189/747, [25%]) included up to nine patients per site for familiarization of the device and protocol; the Pivotal (P) group (n = 480/747, [65%]) was intended for presentation to the FDA for consideration of device approval; and a Bilateral (B) registry group (n = 78/747, [10%]) was included because of the need to treat patients with bilateral carotid artery disease. In the 480 Pivotal patients, anatomic criteria represented the most frequent high-risk surgical category for enrollment (58.8%), followed by prior CEA (34.2%), multivessel (>or=2) coronary artery disease (21.7%), and contralateral carotid occlusion (18.1%). RESULTS: The technical success rate for stent deployment and FilterWire EX/EZ deployment and retrieval was 98.2%. The mean postprocedure angiographic diameter stenosis in the Pivotal group was reduced to 10.8%, while the overall procedure success rate (<50% residual diameter stenosis) after stent deployment was 98%. The 30 day composite major adverse event (MAE) rate for the entire cohort of 747 patients (i.e. inclusive of all 3 groups) was 5.8% (all death = 1.5%, all stroke = 4.4%, and all myocardial infarction (MI) = 1.0%). In subgroup analysis, there was no significant difference in the MAE rate between the three groups (P = 5.8%, R = 6.9%, B = 2.6%, P = 0.42). CONCLUSION: The similarity in periprocedural event rates for the Pivotal and Roll-in groups suggests a flat learning curve for experienced operators using this carotid stent system. The similarity in event rates for the Bilateral group, when compared with the Roll-in and Pivotal groups, suggests that staged sequential treatment of bilateral stenoses may be performed at the same risk as for unilateral lesions. The 30-day safety of this stent and distal emboli protection system is encouraging and compares favorably with other carotid stent trials in high surgical risk patients.

Aged↗

PubMed2006

Transcatheter patent foramen ovale closure using the Premere PFO occlusion system.

OBJECTIVES: To evaluate the safety and efficacy profile of the new Premere patent foramen ovale (PFO) occlusion system. BACKGROUND: Several different devices have been used so far for transcatheter PFO closure but no data has been published so far on the efficacy and safety of the Premere PFO occlusion system. METHODS: Since September 2005, 15 patients (seven males, eight females; mean age 51.2 +/- 10.8 years) at our institution underwent transcatheter PFO closure because of cryptogenic stroke, using the Premere PFO occlusion system. The procedure was performed under fluoroscopic and transesophageal echocardiographic (TEE) guidance in all patients. Seven patients (47%) had an associated atrial septal aneurysm and two patients had had >1 stroke. Five patients (33%) had an associated thrombophilia, whereas three patients (20%) had a diagnosis of migraine headache with aura, by the referring neurologist. Residual shunt was assessed immediately after and 1 month (only in 11 patients) after the procedure by both transcranial Doppler and TEE. RESULTS: Premere PFO devices could be implanted in all patients (20 mm size in seven patients, 25 mm size in eight). Fluoroscopy time was 7.3 +/- 1.9 and procedural time was 11 +/- 3 min (range 7-17 min), reflecting our initial learning curve with this device. No complication occurred during the procedure or at follow-up. A residual shunt was noted immediately after the procedure in eight patients (53%) and at 1 month in 4/11 patients (36%). Residual shunt was mild in all patients. After a median follow-up of 4.2 months (0.2-5.8 months), no patient had a recurrent stroke. All patients with migraine headache with aura had resolution of symptoms. CONCLUSIONS: Our preliminary experience with the Premere PFO occlusion system shows that this device is safe and effective.

Adult↗

PubMed1997

Cannulation of the coronary sinus via the femoral vein--a new technique.

BACKGROUND: Cannulation of the coronary sinus usually has been accomplished by advancing a catheter through the sub-clavian or internal jugular veins. HYPOTHESIS: We have developed a new technique for cannulation of the coronary sinus with a modified 6F Judkins L5 coronary catheter positioned through the femoral vein. RESULTS: The technique was tried successfully in 20 consecutive patients by the same operator and the average fluoroscopy time for coronary sinus cannulation was 1.6 +/- 1.0 min. CONCLUSION: Analysis of the results showed evidence of a learning curve with improvement of time with an increasing number of patients. The method provides a safe and inexpensive solution for catheterization of the coronary sinus, easily accessible to every catheter laboratory.

Catheterization, Peripheral↗

PubMed2005

FilterWire distal embolic protection device for vein graft stenting: initial single-center experience.

BACKGROUND: Saphenous vein graft (SVG) intervention is associated with a significant incidence of major adverse cardiac events (MACE) related to distal vessel embolization. The FilterWire distal embolic protection device has recently been approved as an adjunct to SVG intervention. We report here our initial experience in a single center in 30 consecutive patients using this device in SVG stenting. HYPOTHESIS: This study examined the outcomes and complications associated with these devices, as well as whether proficiency with the devices increased with greater experience and whether there were measurable outcome differences between devices. METHODS: We retrospectively identified all patients in whom a FilterWire device was placed at our hospital between June 2001 and June 2004. RESULTS: The device was successfully deployed in 29 of 30 patients, and all patients were stented successfully. Overall MACE rate was 6.6%, consistent with reports in larger multicenter clinical trials. Transient decreases in flow were noted while the device was in place in six patients, but improved in five patients with device removal. CONCLUSIONS: This early experience in a single center using FilterWire embolic protection indicates that excellent clinical results can be obtained by the adoption of filter protection for SVG intervention, without evidence for a detrimental learning curve.

Aged↗

PubMed2006

Impact of fellowship training on pathologic outcomes and complication rates of radical prostatectomy.

BACKGROUND: The study was conducted to assess the results of radical prostatectomy (RP) performed by fellowship-trained surgeons in the first year of independent practice. METHODS: A prospective cohort study of 66 men who underwent RP performed by 2 recently graduated fellowship-trained surgeons (C.J.R., n = 27; A.M.K., n = 39) in their first year of independent practice was undertaken. Preoperative, operative, and postoperative data were collected and analyzed. Median follow-up of the cohort is 12.5 months. RESULTS: The median patient age was 61.2 +/- 6.9 years (range, 44-74 years), the median prostate-specific antigen level was 5 ng/mL (range, 1.2-39.4 ng/mL), and the median prostate biopsy-determined Gleason score was 7. Of the 66 men, 25 (38%) underwent a bilateral nerve-sparing RP, 20 (30%) underwent a unilateral nerve-sparing RP, and 21 (32%) underwent a nonnerve-sparing procedure. Forty-two men (63%) underwent a pelvic lymph node dissection. The median operative time was 201 minutes. Median estimated blood loss was 734 mL (range, 300-1600 mL). There were 4 major complications--a pulmonary embolism in 3 patients and an intraoperative rectal injury in 1. Pathologic classification was as follows: pT2, 74%; pT3a, 23%; pT3b, 2%; and pN+, 2%. The positive margin rate was 14% overall and only 2% in men with pT2 disease. CONCLUSIONS: Results of RP performed by fellowship-trained surgeons in their first year of practice compare favorably with results of RP in a large series reported by more experienced surgeons. Being trained in an environment where an experienced surgeon serves as first assistant to the trainee appears to abbreviate the learning curve associated with this procedure.

Adult↗

PubMed2003

Design and training of a neural network for predicting the solvent accessibility of proteins.

A feed-forward neural network has been developed to predict the solvent accessibility/accessible surface area (ASA) of proteins using improved design and training methods. Several network issues ranging from the coding of ASA states to the problem of local minima of learning curve, have been addressed. Successful new approaches to overcome these problems are presented. Set of trained network weights for each ASA threshold is provided. It has been established that the prediction accuracy results with neural network are better than other reported results of ASA prediction, despite a high test to training data ratio.

Amino Acids↗

PubMed2004

Prognostic value of sentinel lymph node biopsy in the pathologic staging of colorectal cancer patients.

BACKGROUND AND OBJECTIVES: Over the last decade, lymphatic mapping and sentinel lymph node (sN) biopsy have greatly increased the possibility of identifying nodal metastasis in clinically node-negative patients with melanoma and breast cancer, thus improving the accuracy of pathologic staging. Recently, sN biopsy has been applied also in colorectal cancer. This prospective study aimed to assess its feasibility and accuracy in predicting regional lymph nodes metastases in colorectal cancer patients as well as the impact on treatment decision-making. MATERIALS AND METHODS: Lymphatic mapping was accomplished by means of blue dye, which was intraoperatively injected into the subserosa overlying the tumor site in 26 patients undergoing colorectal cancer surgery. Following bowel resection, the operative specimen was inspected to identify each blue-stained node, the sN, which was sent separately to the pathologist. One half of each sN was examined by multiple 200 microm sections, while the second half was examined by standard bi-valving technique with hematoxylin-eosin (H and E) staining; all the other regional non-sentinel nodes were routinely examined by standard bi-valving technique and H and E staining. RESULTS: At least one sN was detected in 24 of 26 patients (92.3%); two patients with rectal cancer had no sN identified. Overall, 70 sN were retrieved into the operative specimens, with a mean of 2.9 sNs/patient, and 19 sNs were tumor-positive. An agreement between sN and regional lymph-node status was observed in 20 of 24 patients (83.4%). The sN was histologically negative in two of nine patients with positive regional nodes (sensitivity = 77.8%; false-negative rate of 22.2%); in two of seven patients with tumor-positive sN (28.6%), the sN was the exclusive site of regional nodal metastasis. The negative predictive value was 88.2% (15 of 17 patients), and the overall accuracy was 91.7% (22 of 24 patients). As regards the contribution to the detection of nodal metastasis according to the pathologic technique, standard H and E bi-valving technique detected 16 of 19 tumor-positive sNs (84.2%) while, by means of serial sectioning, metastases were detected in the remaining 3 of 19 sNs (15.8%). CONCLUSIONS: The sN biopsy proved feasible, with a rather short learning curve. The focused analysis of the sN by means of serial sectioning improved the detection rate of nodal metastasis compared to standard bi-valving examination, so that a more accurate nodal staging should be expected; finally, an elective localization of metastasis within the sN was observed in almost one third of regional node-positive patients.

Aged↗

PubMed2006

Interpectoral approach to dissection of the axillary apex: an elegant and effective approach.

BACKGROUND: Axillary dissection is the gold standard for treatment of the axilla. It provides important prognostic information, accurately stages the axilla, and has the lowest recurrence rate among all modalities. In today's age of conservation surgery, the axilla is often addressed through a cosmetically acceptable small incision with limited access, thereby making clearance of the level III nodes difficult. METHODS: We describe a method of apical lymph node dissection through the interpectoral plane, which effectively clears the apex despite the constraints of limited exposure. RESULTS: This method has been used in nearly 5,000 axillary dissections performed at our institute, with excellent results. It preserves the innervation of the pectoral muscles and affords access to the interpectoral nodes. CONCLUSIONS: Our method has a short learning curve, provides good exposure of a difficult area and consistently provides a good yield of nodes.

Axilla↗