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. 2021 Mar;13(3):1543–1552. doi: 10.21037/jtd-20-2862

Figure 2.

Figure 2

The CUSUM plot of the number of harvested thoracic lymph nodes in ro-bot-assisted McKeown and Ivor Lewis esophagectomy separately. (A) The CUSUM plot of the number of harvested thoracic lymph nodes in the first 31 cases of robot-assisted McKeown esophagectomy. The tendency of the CUSUM plot changed from downward to upward in the 23rd case. It indicated that it took 23 cases for the surgeons to accomplish the initial exploration of the harvest of the thoracic lymph nodes in the McKeown approach. (B) The CUSUM plot of the number of harvested thoracic lymph nodes in the first 31 cases of robot-assisted Ivor Lewis esophagectomy. The CUSUM plot tended to downward at the beginning, and it reached the lowest point in the 18th case. After that, the CUSUM plot started ascending. It indicated that on the basis of the robot-assisted McKeown lymphade-nectomy, the exploration of the thoracic lymphadenectomy in the Ivor Lewis approach took another 18 cases. CUSUM, cumulative sum.