Variation in the learning curves of general surgery residents performing arteriovenous fistulas

An arteriovenous fistula (AVF), performed for hemodialysis access, provides one of the few remaining opportunities for general surgery residents to perform an open vascular anastomosis (VA). Limited data exist regarding the learning curve of residents performing this procedure. The objective of this study was to determine how residents improve in performance of VA by implementing real-time tracking of anastomosis time as well as technical errors.

From April 2012 to January 2014, we conducted a prospective intraoperative assessment of 9 postgraduate year 3 general surgery residents during the performance of AVFs using a checklist of common errors in VA. Time for AVF anastomosis completion and number and types of technical errors during anastomosis were recorded. Primary end points were the change in anastomosis time and change in technical errors over time.

A total of 86 AVFs were performed and assessed intraoperatively. Each resident performed a median of 10 AVFs (interquartile range [IQR]: 7-11). The mean anastomosis time was 18.1 minutes. The mean number of technical errors was 13.8 per case. Overall, for every additional AVF performed, mean anastomosis time decreased by 0.63 minutes (95% CI: 0.45-0.81, p < 0.0001) and the mean number of technical errors decreased by 1.0 (95% CI: 0.7-1.3, p < 0.0001). The greatest improvement in overall errors (mean difference = 7.9, p = 0.03) and time (mean difference = 4.7min, p = 0.03) occurred after the performance of 3 AVFs. However, when analyzed by individual resident, the R(2) value for anastomotic time by number of AVFs performed ranged from 0.01 to 0.69. Similarly, for technical errors, the R(2) value by number of AVFs performed ranged from 0.04 to 0.62.

In novice surgical residents performing AVFs, improvement in VA skill can readily be tracked via anastomosis time and technical errors. Collectively, there is a strong association between number of cases performed and reduction in time and errors. However, individually, the number of cases completed did not correlate well with time and errors. These findings suggest that for VA skills, determining progression from novice to competence cannot rely on case volume but rather needs to be individualized.