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Implementing clinical protocols in oncology: quality gaps and the learning curve phenomenon.

BACKGROUND: The quality improvement effort in clinical practice has focused mostly on 'performance quality', i.e. on the development of comprehensive, evidence-based guidelines. This study aimed to assess the 'conformance quality', i.e. the extent to which guidelines once developed are correctly and consistently applied. It also aimed to assess the existence of quality gaps in the treatment of certain patient segments as defined by age or gender and to investigate methods to improve overall conformance quality. METHODS: A retrospective audit of clinical practice in a well-defined oncology setting was undertaken and the results compared to those obtained from prospectively applying an internally developed clinical protocol in the same setting and using specific tools to increase conformance quality. RESULTS: All indicators showed improvement after the implementation of the protocol that in many cases reached statistical significance, while in the entire cohort advanced age was associated (although not significantly) with sub-optimal delivery of care. A 'learning curve' phenomenon in the implementation of quality initiatives was detected, with all indicators improving substantially in the second part of the prospective study. CONCLUSIONS: Clinicians should pay separate attention to the implementation of chosen protocols and employ specific tools to increase conformance quality in patient care.

Adult↗

Laparoscopy-assisted distal gastrectomy with systemic lymph node dissection: a phase II study following the learning curve.

BACKGROUND AND OBJECTIVES: A preliminary study on the use of laparoscopy-assisted approach to treat gastric carcinoma resulted in higher morbidity. STUDY DESIGN: A prospective phase II study of laparoscopy-assisted distal gastrectomy (LADG) was performed for patients with preoperative diagnosis of T1 N0 stage cancer located in the lower or middle-third stomach. Bleeding amount, operating time, mortality, morbidity, and the number of lymph node retrieval were recorded and compared with the preliminary series reported previously by the same authors. RESULTS: Between 2000 and 2002, 47 patients were accrued. The mean blood loss and postoperative hospital stay were significantly decreased compared with the previous series, whereas the operating time was not. There were no in-hospital deaths, with the incidence of anastomotic leakage significantly decreased. All patients remain disease-free to date. CONCLUSIONS: LADG can be performed safely and morbidity, no longer, is a drawback by experienced hands that have reached plateau of the learning curve, although it remains a time-consuming procedure. Its application to gastric cancer surgery is feasible for early stage cancer, and its applicability to the treatment of T2 stage cancer will be the next issue to be explored.

Adult↗

Learning curve, surgical results and operative complications for kidney transplantation in mice.

Murine transplant models of vascularized organs are very useful for immunobiological studies. However, the technique of kidney transplant is complex and very demanding. Here, results of the first successive 50 syngeneic transplantations performed by an experienced microsurgeon are reported. Complications and survival rates were recorded and analyzed over the different training phases. While the operative time and warm ischemia time dramatically reduced after 40 transplants (warm ischemia after 40 transplants 33.1+/-5.0 min vs. 55.2+/-4.6 min for the first 10 transplants, P<0.001), the average early vascular anastomosis patency rate markedly increased (80% vs. 10% in the first than transplants, P<0.01). Intraoperative failures were 56% (n=28), death during the first 7 days was 18% (n=9), and death after contralateral nephrectomy (>day 7) was 10% (n=5). Only 8% (n=4) of the animals survived long-term. Despite large experience with microsurgery, there is a relative long learning curve for mouse kidney transplantation.

Anastomosis, Surgical↗

Predictors of complications and learning curve using the Angio-Seal closure device following interventional and diagnostic catheterization.

A retrospective study was conducted to determine the frequency and nature of groin complications when the Angio-Seal device was used on 252 occasions by one operator immediately following interventional (66%) and diagnostic (34%) procedures. Sixty-nine percent of the 238 successfully deployed cases received ticlopidine or clopidogrel, 16% received abciximab, and 15% received heparin postprocedure. Complications included vascular surgery for collagen plug perforation into the femoral artery (0.8%), failure to deploy (5.6%), pseudoaneurysm (0.4%), brisk, visible bleeding (9%), persistent ooze (14%), hematoma > 6 cm (0.8%), hematoma </= 6 cm (2.4%), and ecchymosis > 1 cm(2) (10%). Multivariate analysis identified diagnostic cases (6 Fr sheaths) to be associated with a reduced risk of complications [odds ratio (OR) 0.1] while interventional procedures (8 Fr sheaths), postprocedure heparin, and body mass index (BMI) < 28 (OR 10.1, 3.2, and 2.8, respectively) were associated with increased risk. Gender, age, ticlopidine, clopidogrel, and abciximab were not independent predictors of complications. A learning curve for device deployment was observed in the first 50 cases (14% nondeployment vs. 3.5% for the subsequent 202 procedures, P = 0.009) and failure to deploy was independent of sheath size used. Angio-Seal can be used with reasonable safety and efficacy immediately after diagnostic and interventional procedures. Cathet. Cardiovasc. Intervent. 48:162-166, 1999.

Adult↗

The impact of endoscopists' experience and learning curves and interendoscopist variation on colonoscopy completion rates.

BACKGROUND AND STUDY AIMS: Since its introduction in the late 1960s, the technology of colonoscopy has developed rapidly and the competence of endoscopists has increased. Nevertheless, it is not always possible to perform a complete colonoscopy. The aim of this study was to assess, in a population-based setting, the endoscopist-related factors influencing the completion rate, taking into account patient characteristics and changes in the technology over time. PATIENTS AND METHODS: All colonoscopy records between 1979 and 1995 in one Swedish county (population 258,000) were retrieved. Information was obtained about patient demographics, date of examination, endoscopist, indications, presence of diverticulosis, type of colonoscopy, findings, level of completion, complications, and reasons for incomplete colonoscopy. Completion rates were examined by univariate and multivariate analyses. RESULTS: Of 5,494 colonoscopies, 4,153 (75%) were complete, and 78% were diagnostic and 22% therapeutic. In 70 %, findings were pathological, and 30 % were normal. The overall 30-day endoscopist-related complication rate was 0.3 %. Over time, the proportion of colonoscopies performed by endoscopists with greater experience increased and so did the completion rates. Completion rates were influenced by endoscopist's experience and to some extent by the intensity (the number of colonoscopies performed by the endoscopist during the previous 90 days). There was a large interendoscopist variation, at each level of experience, in the ability to perform a complete colonoscopy, implying substantial differences between individual learning curves. CONCLUSIONS: The completion rate has increased over time, the major reason being greater competence of endoscopists. The finding of large interendoscopist variation, at each level of experience, in the ability to perform a complete colonoscopy supports the monitoring of endoscopists to maintain and improve performance.

Adolescent↗

The learning curve in vestibular schwannoma surgery.

OBJECTIVE: This study aimed to examine the effect of surgical team experience on facial nerve function and complication rate in vestibular schwannoma surgery. STUDY DESIGN: The study design was a retrospective analysis of a case series. SETTING: The study was conducted at a tertiary referral center. PATIENTS: One hundred sixty consecutive patients undergoing vestibular schwannoma excision participated. INTERVENTION: Surgical excision of vestibular schwannoma via a translabyrinthine, middle cranial fossa, suboccipital, or combined approach was performed. MAIN OUTCOME MEASURES: Facial nerve function (House-Brackmann score) and complication rates including cerebrospinal fluid leak and meningitis compared by groups of 20 patients were measured. RESULTS: There was a statistically significant improvement in the number of patients achieving a House-Brackmann grade I result between the first 20 patients (35% House-Brackmann grade 1) and the ensuing 7 groups of 20 patients (74% House-Brackmann grade 1) by chi2 analysis. When considering House grades I and II together, there was no statistically significant difference in facial nerve function in the first 20 patients (80%) compared to the last 7 groups of 20 patients (88%) by Tukey's pairwise comparisons (p = 0.245). Mean tumor size was not significantly different in the groups studied (p = 0.54). The total cost of patient care declined over the study period; however, the wide case-to-case variance made it so that this trend was not statistically significant (p = 0.448). CONCLUSIONS: A learning curve of 20 patients was demonstrated by this study to have been necessary for attaining acceptable standards in the surgical removal of vestibular schwannomas by a new surgical team. The findings of this study may have implications for patient care and surgeon training.

Adolescent↗

The regional anesthesia "learning curve". What is the minimum number of epidural and spinal blocks to reach consistency?

BACKGROUND AND OBJECTIVES: Wide variability exists in the amount of regional anesthesia practice to which residents are exposed during training. The number of attempts at various blocks before a trainee becomes proficient at performing these regional anesthetic techniques is not known. This study addresses the question: What is the minimum number of blocks a resident must perform to reach consistency during training in these techniques? METHODS: Every regional anesthetic technique attempted by all beginning CA-1 anesthesiology residents (n = 7) during their first 6 months of training (July 1993 to December 1993) were recorded on a daily basis. Nonregional anesthetic techniques attempted were recorded for comparison. The objective measures used to define the degree of success were obtaining cerebrospinal fluid during attempted spinal anesthesia, subsequent anesthetic block during epidural placement, and detection of end-tidal carbon dioxide for endotracheal intubation. RESULTS: An average of 77 +/- 9 epidural anesthetics, 44 +/- 6 spinal anesthetics, and 86 +/- 13 endotracheal intubations were attempted during the 6 months of training. The learning curves for each technique are of similar shape. Residents show significant (P < .05) improvement over baseline after 20 spinal and 25 epidural anesthetics, but a 90% success rate is not reached and maintained until 45 spinal and 60 epidural anesthetics are performed. CONCLUSIONS: Approximately 20-25 procedures each are necessary before improvement in the techniques of spinal and epidural anesthesia is demonstrated by residents in training. If a 90% success rate is desired, 45 and 60 attempts at spinal and epidural anesthesia, respectively, may be necessary.

Anesthesia, Conduction↗

Mitral valvuloplasty: a learning curve.

Failure to appreciate the importance of each of the functional components of the mitral valve has resulted in general disenchantment with the results of mitral valve annuloplasty. Consequently, the technique of mitral valvuloplasty evolved. From January 1981 through March 1982, 100 patients underwent mitral valvuloplasty. The following basic techniques were used: commissurotomy (55 patients), chordal resection (95 patients), shortening (52 patients) and fenestration (16 patients), resection of leaflet tissue (16 patients), and Carpentier-Edwards ring insertion (69 patients). Two consecutive groups of patients were compared. In group 1 (the first 30 patients) there were four early and two late deaths; in group 2 (the remaining 70 patients) there were no early and two late deaths. Three patients in each group required a subsequent valve replacement (p less than .01). Hence, the linear valve failure rate was 12.2% and 4.8% a patient year for groups 1 and 2, respectively. Seventy-one percent of the survivors in group 1 and 84% of those in group 2 had no or only mild residual mitral valve dysfunction. Poor initial results should not discourage surgeons because mitral valvuloplasty has a striking learning curve.

Adolescent↗

Flap complications in our learning curve of laser in situ keratomileusis using the Hansatome microkeratome.

PURPOSE: To determine the incidence and the type of flap complications in our initial series of eyes undergoing laser in situ keratomileusis and the impact of microkeratome-related complications on best spectacle-corrected visual acuity. METHODS: We reviewed the charts of the 630 consecutive eyes operated in the Refractive Surgery Department of Cerrahpasa Medical School, University of Istanbul, Turkey using the Hansatome microkeratome and the Summit, SVS Apex Plus excimer laser between March 1998 and November 1999. The mean follow-up was 12.6 months. RESULTS: The incidence of total flap complications was 19.8%. Flap folds (5%) were the most common complication. The incidence of epithelial ingrowth was 3.3%. Diffuse lamellar keratitis was encountered in 20 cases (3.17%). Displaced flaps were seen shortly after the procedure in 8 eyes (1.26%) and repositioned immediately. Improper keratectomy occurred in 14 eyes (2.2%) and incomplete keratectomy in four procedures (0.63%). The presence of interface debris and hemorrhage was each 1.9%. We observed one interface abscess, which was culture-negative and cured with fortified antibiotics, and one free flap. CONCLUSIONS: Although the LASIK procedure with the Hansatome had an easy learning curve without any of the serious complications that frequently occur in this phase, we still observed flap related complications that affected visual outcome.

Adult↗

Learning curve for laparoscopic ventral hernia repair.

PURPOSE: To test if there was any difference in the indications and early outcomes of laparoscopic ventral hernia repair (LVHR) during a 36-month period at a single institution. METHODS: From August 1999 to August 2002, 64 consecutive, unselected patients underwent attempted LVHR. The patients were retrospectively divided into two groups: group 1 included the first 32 patients, and group 2 included the second 32 patients. Data regarding patient demographics, results, and postoperative follow-up were compared between the groups. RESULTS: Demographic characteristics, types of hernia, preoperative records, and hernia defects were well matched between the groups. Four patients in group 1 required conversion to laparotomy for bowel injuries, whereas no conversion was required in group 2 (12% vs 0%, P = 0.11 [NS]). The operative times and complication rates were similar, but bowel injuries were significantly more common in group 1 (19% vs 0%, P = 0.02), including the patients who were converted. The analgesic requirement was small and the hospital stay short in both groups; the differences were not significant. Three recurrences were noted in group 1 and none were noted in group 2, although follow-up was not comparable in the second group. CONCLUSIONS: A learning curve is needed to decrease conversions and bowel injuries during LVHR. The improved experience could permit the treatment of larger defects laparoscopically.

Adult↗

Transition from open to laparoscopic fundoplication: the learning curve.

BACKGROUND: Two of us (B.C.S. and C.W.D.) began performing laparoscopic fundoplication in 1992. We have always designated the resident as the operating surgeon. OBJECTIVE: To determine the time necessary for both experienced surgeons and residents to become proficient in laparoscopic fundoplication. DESIGN: The medical records of 241 consecutive patients undergoing laparoscopic fundoplication were reviewed. This period started with the implementation of the procedure in January 1992 and ended in March 1998. For 3 consecutive years, residents were given a questionnaire regarding their confidence in performing laparoscopic fundoplication. RESULTS: Laparoscopic fundoplication was attempted in 241 patients and completed in 203 patients (84%). Comparing the first 25 attempted laparoscopic fundoplications with the second 25, there were 14 conversions (56%) vs 4 conversions (16%) (P<.01). Average operative times decreased from 236 to 199 minutes (P<.05), and the intraoperative complication rates were 5 (20%) and 1 (4%), respectively. Subsequently, the conversion rate stabilized at 2%. The operative time continued to decline to an average of 99 minutes for the last 25 laparoscopies. Senior residents and recent graduates returning the questionnaire performed an average of 112 laparoscopic procedures, including 15.7 laparoscopic fundoplications. They felt comfortable with the procedure after performing an average of 10.6 operations. CONCLUSIONS: The learning curve is very steep for the first 25 laparoscopic fundoplications for experienced surgeons. However, improvements, as judged by decreases in operative time, conversion rate, and intraoperative complications, continue to occur after 100 cases. Under supervision, residents can become comfortable with this procedure after about 10 to 15 procedures.

Clinical Competence↗

Effect of the learning curve on the early outcomes of laparoscopic Roux-en-Y gastric bypass.

Open gastric bypass has been demonstrated to provide durable weight loss in morbidly obese patients. As laparoscopic techniques have evolved surgeons are offering patients such an approach for performance of gastric bypass. The purpose of this study was to evaluate the relationship between increasing experience and outcome for this technically challenging operation. A retrospective analysis was performed on the initial 160 consecutive patients undergoing laparoscopic gastric bypass by a single surgeon over a 24-month period. Patients were divided into quartiles for data analysis. Duration of surgery decreased significantly between quartiles: 324 +/- 124, 225 +/- 70, 190 +/- 47, and 168 +/- 40 minutes, respectively (P < 0.01). However, the conversion rate (3.1%) and mean hospital length of stay (2.1 +/- 2.4 days) were unaffected by surgeon experience. The early and late postoperative complication rates were 9.4 and 3.1 per cent, respectively. Early complications included: leak (1.3%), bleeding (3.8%), obstruction (1.9%), acute gastric distention (0.6%), subphrenic abscess (0.6%), and wound infection (0.6%). Late complications include: obstruction (1.3%), anastomotic stricture (1.3%), and marginal ulcer (0.6%). The complication rates did not change statistically between quartiles. The excess weight loss at one year was 77.4 +/- 16.7 per cent. These data suggest that throughout the learning curve laparoscopic gastric bypass can be accomplished with acceptable complication rates, conversion rates, and hospital length of stay. Duration of surgery improves with experience. Early weight loss results compare favorably with those of open gastric bypass.

Adult↗

Learning curves and certification for breast cancer lymphatic mapping.

To determine the usefulness of lymphatic mapping and SLN biopsy, two distinct aspects of the technique must be evaluated, mapping success rates and mapping accuracy. The mapping success rate simply reflects the ability to successfully map a SLN. Mapping accuracy is reflected by the false-negative rate defined as the proportion of patients with axillary metastases among those in whom the SLN is negative for disease. It is critical within each institution that these two measurements be obtained to validate the multidisciplinary collaborative effort. It seems that surgeons with appropriate training should be able to map with 85% efficiency with zero or one false-negative cases in their first 10 patients with metastatic disease. It is our recommendation that individual surgeons join together and follow an institutional (IRB approved) protocol for lymphatic mapping in which each surgeon is required to perform at least 30 procedures of SLN biopsy followed by completion axillary lymph node dissections (phase I). There are several advantages for surgeons and patients to participate in national trials as a new technique is established: 1. Patients are fully informed. 2. For those patients who have SLN biopsy followed by a CLND (phase I), there is still an added advantage in that the SLN can be scrutinized more closely resulting in more accurate staging. 3. The surgeon and the institution can be reimbursed even while the surgeon is on the learning curve. 4. It provides for good publicity for the institution. The data should be reviewed for each surgeon after completing the first 30 cases. If the aforementioned goals of 85% success with one or fewer false-negative cases is achieved, then the individual surgeon may move on to a second (phase II) mapping protocol. In phase II, a SLN biopsy is performed and a CLND is performed only if a SLN cannot be located or the SLN contains metastases. Should the aforementioned criteria not be met, then additional procedures or onsite intraoperative mentoring may be required to further evaluate the deficiencies of the mapping procedure by the surgeon or institution. Remember that failure to map may be a function of surgical skill, nuclear medicine injection methodology, or the pathologic evaluation of the SLN. Should institutional problems arise, onsite mentoring may be helpful by someone with adequate mentoring skills to troubleshoot a potential problem. The previously outlined recommendations are similar to the recently published requirements of the American Society of Breast Surgeons that recommend documentation of 30 cases or more with an 85% or higher success rate in identifying a SLN and 5% or greater false-negative rate (single false-negative SLN in the series). A national network of training centers is being established for radioguided surgery. This new technology has the potential of being applicable to 350,000 new cases of cancer diagnosed annually in the United States. Applications include breast cancer, melanoma, and other skin tumors like Merkel cell carcinoma and poorly differentiated squamous cell carcinoma, parathyroid localization, vulvar and vaginal lesions, and bone localization. This network of training centers will provide an opportunity for surgeons, nuclear medicine physicians, and pathologists to come together and learn about this new technology. Training will include didactic sessions, live surgery, and hands-on experience with animal models. The faculty will consist of leading experts from across the country. Participating centers include the H. Lee Moffitt Cancer Center and Research Institute, John Wayne Cancer Institute, and the M.D. Anderson Cancer Center. Training sites will also be available in Durham, NC; Pittsburgh, PA; Seattle, WA; Little Rock, AR; and St. Louis, MO. The network provides access to a national lymphatic mapping database (http:/(/)mapping.rad.usf.edu), participation in national trials, and web site listings (melanoma.net, or breastdoctor.com, and endocrine

Axilla↗

Learning curve in ultrasonographic screening for selected fetal structural anomalies in early pregnancy.

OBJECTIVE: To assess the value of first trimester screening by ultrasonography in detecting structural anomalies of the fetus in a general obstetric population. METHODS: During 1993-1998, 20,465 consecutive pregnant women who resided in a defined geographic area participated in ultrasonographic screening for major malformations. These included anomalies of the central nervous system, urinary tract, abdominal wall, and long bones. Heart anomalies were not expected to be detected. The examinations were offered at 13-14 weeks' gestation as part of routine maternal care and were done by specially trained midwives. The pregnancy outcomes were ascertained from obstetric and pediatric records, and the data were completed by information from the national birth and malformation registries. RESULTS: A total of 307 fetuses (1.5%) with a major malformation were found; 67 fetuses (0.3%) had noncardiac major structural defects expected to be detectable by ultrasonography in early pregnancy. Thirty-five of 67 (52%) were identified at the early scan. Sensitivity for these defects increased from 22% to 79% from the first to the last (sixth) study year (P =.009). CONCLUSION: In a low-risk population, adequate sensitivity in screening for major malformations by early ultrasonography can be achieved after a learning curve of 3-4 years.

Adolescent↗

The learning curve is rapid in medical termination of pregnancy--first-year results from the Helsinki area.

Medical termination of pregnancy by means of mifepristone and prostaglandin became available in Finland in May 2000. We summarize the first year results of medical abortion in a large tertiary care unit in Helsinki. A regimen of 200 mg of mifepristone followed by 0.4 mg vaginally administered misoprostol 2 days later was used. The maximum duration of pregnancy was 56 days. Four hundred and seventeen women, 47% of those with a pregnancy duration of up to 56 days, chose medical instead of surgical abortion. The monthly percentage of medical abortions varied from 27% to 63%. The percentage of complete terminations increased from 92% among the first quarter of the subjects to 97% among the fourth quarter, the overall success rate being 95%. Subject satisfaction, duration and self-estimated amount of bleeding, as well as analgesia needs were similar to those reported elsewhere. Most subjects (61%) chose combined oral contraceptive (COC) pills for future contraception; 75% of the COCs were started around the day of misoprostol administration. The reported amounts and duration of bleeding were not influenced by the immediate start of oral contraceptives. Intrauterine contraception was planned for 28% of the subjects, and 16% of them chose a levonorgestrel-releasing intrauterine device. We conclude that the learning curve in medical termination of pregnancy is rapid, and results comparable to those in centers with extensive experience with the method can be reached within the first year.

Abortifacient Agents, Nonsteroidal↗

The "learning curve" in videoscopic Heller myotomy.

OBJECTIVES: In the early 1990s, minimally invasive videoscopy was applied to numerous operations. After undertaking more than 50 "open" Heller myotomies, our experience with videoscopic Heller myotomy began in 1992. We sought to determine whether the outcome following videoscopic Heller myotomy is influenced by surgeon experience. METHODS: Seventy-eight patients with severe dysphagia secondary to achalasia underwent videoscopic Heller myotomy between 1992 and 1998. Intraoperative endoscopy was utilized to ensure adequate myotomy in all patients. Patients were stratified into 3 groups: the first 25 patients (group I), the second 25 patients (group II), and the last 28 patients (group III). Clinical outcome was based on length of stay, incidence of intraoperative complications, conversion to an 'open' procedure, and postoperative symptoms. RESULTS: Perioperative complications occurred in 20% of patients in group I compared with 8% and 12% in groups II and III, respectively (P = NS). Only 3 patients required conversion to an 'open' procedure, all in group I (P <0 .05). Symptomatic improvement was achieved in 80% of patients in group I, 100% in group II, and 96% in group III (P < 0.05). Significant reductions in conversions to open, length of stay, and postoperative symptoms were seen after 20 myotomies were undertaken. CONCLUSION: Outcome following videoscopic Heller myotomy, like other videoscopic operations, improves as surgeons progress along the videoscopic "learning curve." After approximately 20 videoscopic Heller myotomies, surgeons can expect fewer conversions to open procedures, shorter hospital stays, and better symptomatic relief.

Cardia↗

[Surgical learning curve for creation of vascular accesses for haemodialysis: value of medico-radio-surgical collaboration].

INTRODUCTION: Creation of a vascular access (VA) for haemodialysis is a surgical procedure which comprises a failure rate related to the quality of the vessels and the operator's experience. The authors report the first 2 years of a young urologist's experience with this procedure in a local hospital in collaboration with the nephrology team. PATIENTS AND METHODS: Patients undergoing creation of VA were divided into 2 chronological groups. The patient's age and gender, the cause of renal failure, the presence of diabetes, clinical examination of the upper limb, preoperative assessment of upper limb vessels, the type of anaesthesia, the operating time and the start of dialysis after the operation, as well as the functional results of the VA at 6 months were studied. Results concerning the patients of the first period were discussed by the operator and the nephrology team. RESULTS: During the first 9 months, 28 patients were operated, corresponding to 36 operations including 32 direct fistulas. Over the following 15 months, 61 patients were operated, with the creation of 63 VAs, including 55 direct fistulas. The failure rate (thrombosis or non-functioning VA) decreased from 32.1% to 11.1% (p=0.07), while the 2 groups were globally comparable. CONCLUSION: Evaluation of a new surgical procedure shows a number of failures, as for all learning curves. However, it helps to improve the results. Collaboration with nephrologists must comprise a discussion allowing the acceptance of certain failures, as they reflect compliance with a strategy of preservation of the vascular capital and a rational attempt to avoid a non-essential proximal access or bypass graft. The support of a motivated radiology team (preoperative assessment and management of complications) and the assistance of a more experienced operator are essential.

Catheters, Indwelling↗