Robotic Low Anterior Resection Research Articles

Simultaneous robotic surgery with low anterior resection and prostatectomy/hysterectomy.

Cooperation with multiple departments is essential for the treatment of patients with rectal cancer and other pelvic cancers. In our department, we experienced two cases of rectal cancer that underwent robotic low anterior resection (LAR) and simultaneous resection of other pelvic organs (case 1 with prostatectomy and case 2 with hysterectomy) using the da Vinci Xi system. Here, we show the precise procedures of these two robotic surgeries. Under general anesthesia and lithotomy position, five da Vinci ports were symmetrically placed along the umbilical horizontal line with a 7cm interval, and a 5mm AirSeal Access Port was added in the right or left upper quadrant. Patients were placed with 22-degree Trendelenburg and 8-degree tilt to the right. The operators used the center port on the umbilicus as a camera port and chose the docking arms with either two-left-one-right or one-left-two-right setting depending on their preference. This port setting was quite useful for the operators from multiple departments to change the docking arms, even if their preference may be different. Moreover, assistants could use the remaining two ports to provide a well-expanded and safer surgical field. "With a familiar view" and "with a wide view" are our two concepts to safely perform extended pelvic surgeries. We have employed this symmetrical horizontal port site position as a general setting for usual rectal surgeries.

89P - Prevention and management of low rectal anastomotic leakage in the robotic era: A propensity score matched study

Background: Anastomotic leakage (AL) is a severe complication of robotic low anterior resection (LAR) for rectal cancer, and effective prevention is urgently needed. In the robotic era, to evaluate the role of innovative techniques that prevented AL in rectal cancer patients undergoing robotic LAR. Methods: From September 2012 to September 2017, a total of 581 patients underwent robotic LAR, with 131 patients participated as control subjects (non-PST group) and 450 patients were subjected to PST techniques. After propensity scores adjusted for potential bias, the AL rate, short-term and long-term outcomes were compared between the two groups. Results: The overall rate of AL was 7.1% out of 581 patients, with Grade B at 6.2% and Grade C at 0.9%, using the ISREC grading system. After matching propensity scores, the PST group presented improvement in both overall AL (5.0% vs 10.7%, P = 0.034) and major AL (0.4% vs 3.1%, P = 0.044) compared with the non-PST group, respectively. Furthermore, the PST group had lower surgical complications (13.6% vs 21.6%, P = 0.014) and reoperation rates (0.8% vs 4.6%, P = 0.019) compared with the non-PST group, respectively. Long-term oncological outcomes were not significant in the two groups. By multivariate regression models, we demonstrated that distance of anastomosis from anal verge <5cm, distance of distal resection margin from tumor <2cm, estimated blood loss ≥100mL and non-PST technique were risk factors of AL in robotic LAR. Conclusions: Avoiding routine diverting stoma, the innovative PST techniques may shed light on an effective method for preventing occurrence of AL in robotic LAR. Legal entity responsible for the study: Zhongshan Hospital, Fudan University. Funding: Supported by The National Natural Science Foundation of China (81602035, 81472228); The Shanghai Municipal Commission of Health and Family Planning: Shanghai Outstanding Youth Specialist Training Program (Q2017-059); Clinical Science and Technology Innovation Project of Shanghai (SHDC12016104). Disclosure: All authors have declared no conflicts of interest.

Robotic low anterior resection plus transanal natural orifice specimen extraction in a patient with situs inversus totalis

BackgroundSitus inversus totalis (SIT) refers to an unusual condition involving reversal of abdominal and thoracic viscera, with an incidence rate of 1/5000–20,000 adults. Minimally invasive surgeries for SIT patients are technically challenging, while the surgical experience for SIT patients is quite limited.Case presentationA 61-year-old man, previously diagnosed as SIT, came to our hospital for 6 months history of hematochezia and altered bowel habit. A diagnosis of rectal cancer was made in view of colonoscopic biopsy which confirmed an irregular circumferential lump of well differentiated adenocarcinoma at 10 cm from the anal verge. The computed tomography contrast-enhanced (thorax + abdomen + pelvis) scan revealed a total transposition of abdominal and thoracic organs and an enhanced eccentric mass of rectal but with no evidence of distant metastasis. Robotic low anterior resection (LAR) plus transanal natural orifice specimen extraction (NOSE) was performed after obtaining informed consent. The procedure was performed successfully and the patient convalesced nicely without any complications. The postoperative pathological diagnosis revealed a 4x4x0.6 cm3 moderately differentiated adenocarcinoma and circumferential clearance.ConclusionsRobotic LAR plus transanal NOSE for rectal cancer patients with SIT can be performed safely and may be an effective approach in contrast to open or laparoscopic approach, despite the unconventional anatomy.

Robotic-assisted total mesorectal excision (TME) for rectal cancer results in a significantly higher quality of TME specimen compared to the laparoscopic approach—report of a single-center experience

Robotic surgery allows for a better visualization and more precise dissection especially in the narrow male pelvis and mid and lower third of the rectum. However, superiority to laparoscopic TME has yet to be proven. We therefore analyzed short-term outcomes of laparoscopic and robotic low anterior rectal resection for rectal cancer. From 2011 to 2016, 44 robotic (RTME) and 41 laparoscopic (LTME) low anterior rectal resection with total mesorectal excision were performed at a single institution. Specimen quality was assessed and reported by an independent pathologist following international guidelines. The groups did not differ significantly regarding gender, age, ASA stage, BMI, and distance of the lower tumor margin from the anal verge. More patients in the RTME group underwent preoperative chemoradiation (43.2 vs. 19.5%, p = 0.019). The quality of the TME specimen was significantly better in the RTME group (complete/nearly complete/incomplete for RTME 97/0/3% and for LTME 78/17/5%, p = 0.03). The conversion rate tended to be lower in the RTME group (7 vs. 17%, p = 0.143). There was no difference in CRM positivity between the groups. Robotic surgery is safe and can improve the quality of TME for rectal cancer compared to laparoscopy. Any effect on long-term survival remains to be established.

An Innovative Way of Tumor Localization in Robotic Rectal Cancer Surgery: Using the “FIREFLY” Mode in Da Vinci Xi Robot

Introduction: Near infrared technology is used in transplant surgeries, partial nephrectomies, and colorectal surgeries to assess to perfusion at anastomotic sites, identify hidden vessels, and assess blood supply to bowel segments.1–4 The same technology (Firefly) is installed currently on da Vinci Si and Xi robotic systems (Intuitive Surgical, Inc., Sunnyvale). This technology requires ICG (indocyanine green) dye injection. In small rectal tumors which are below the peritoneal reflection and which are difficult/not palpable by digital rectal examination, ensuring a safe distal resection margins while saving maximum rectal stump is difficult. Localizing such tumors with rigid/flexible sigmoidoscope requires dimming/turning off light coming from robotic endoscope, which makes marking the point of transection difficult and unsafe. This video describes a technique to precisely identify the distal trisection point using Firefly mode without the ICG dye, in robotic rectal cancer surgeries. In Firefly mode the entire field is still clearly visible to safely navigate and mark the point of distal transection. Materials and Methods: This is an 18-year-old male patient with a rectal cancer 10 cm above the anal verge. A robotic low anterior resection was performed with splenic flexure mobilization. The distal rectum is dissected until the pelvic floor is reached. Rigid sigmoidoscopy is performed in Firefly mode. The rigid sigmoidoscope is pressed against the anterior wall of the inflated rectum, below the level of tumor and this point of contact shines Firefly green. This point on the rectal wall is marked with methylene blue. This mark acts as a guide for the distal stapler transection once the Firefly mode is discontinued. Results: This method is used in three patients of rectal cancer. All had uneventful postoperative recovery. Final histopathology report showed that two had moderately differentiated adenocarcinoma, whereas one had Signet ring adenocarcinoma. The distal resection margins were clear in all three cases. Conclusion: This technique gives better tumor localization than finger examination or rigid sigmoidoscopy alone when the tumor is small, below the peritoneal reflection, and not easily palpable per anally. With a single switch on the robotic surgeon's console, Firefly mode is switched on. The greenish hue does not limit observation and the light of the sigmoidoscope below the tumor is easily identified. The distal site of transection can be marked without ICG dye and the abdominal dissection remains in clear view. This innovative technique ensures a safe distal resection margin before the stapler is fired while never losing sight of the abdominal dissection. No competing financial interests exist. Runtime of video: 9 mins 58 secs

Totally robotic single docking low anterior resection for rectal cancer: pearls and pitfalls.

Total robotic resection of mid- and low rectal cancers confers technical advantages within the confines of the pelvis and allows difficult rectal cancer cases to be performed efficiently with less risk of conversion to open. To maximize the advantage of robotic surgery, we utilize the technique of single docking totally robotic dissection for rectal cancer for both the Da Vinci Si and Xi Surgical Systems. All steps are performed robotically, with the surgery divided into two phases. The first phase consists of inferior mesenteric artery and vein ligation, sigmoid and descending colon mobilization and splenic flexure takedown. Phase two is rectal dissection and pelvic total mesorectal excision. In this article, which is complemented by a video, we describe in detail our surgical technique for totally robotic dissection for rectal cancer using a standardized 'medial to lateral' approach with emphasis on the pearls and pitfalls of this surgery.

Laparoscopic Bilateral Ovarian Transposition in a Patient with Stage 3 Rectal Adenocarcinoma: Case Report and Literature Review

Abstract Background: In young women undergoing radiation therapy for pelvic or low abdominal cancers, ovarian failure is a major concern and every attempt should be made to avoid it. This article describes a case of a young female patient with rectal adenocarcinoma who underwent laparoscopic bilateral ovarian transposition prior to pelvic radiation and chemotherapy. Case: A 27-year-old female presented with abdominal pain, diarrhea, and intermittent rectal bleeding of 2 months' duration. Colonoscopy revealed a large frondlike/villous, fungating, ulcerated, nonobstructing mass that was suspicious for malignancy. Biopsy confirmed moderately differentiated rectal adenocarcinoma. The patient elected to undergo laparoscopic ovarian transposition in an attempt to preserve her ovarian function. Subsequently, the patient underwent robotic low anterior resection of the rectum. Results: The patient's regular menstruation resumed after surgery, and she has not had any symptoms of ovarian failure or cancer recurrence...

Robotic proctectomy for rectal cancer: analysis of 71 patients from a single institution.

Despite increasing use of robotic surgery for rectal cancer, few series have been published from the practice of generalizable US surgeons. A retrospective chart review was performed for 71 consecutive patients who underwent robotic low anterior resection (LAR) or abdominoperineal resection (APR) for rectal adenocarcinoma between 2010 and 2014. 46 LARs (65%) and 25 APRs (35%) were identified. Median procedure time was 219minutes (IQR 184-275) and mean blood loss 164.9cc (SD 155.9cc). Radial margin was negative in 70/71 (99%) patients. Total mesorectal excision integrity was complete/near complete in 38/39 (97%) of graded specimens. A mean of 16.8 (SD+/- 8.9) lymph nodes were retrieved. At median follow-up of 21.9months, there were no local recurrences. Robotic proctectomy for rectal cancer was introduced into typical colorectal surgery practice by a single surgeon, with a low conversion rate, low complication rate, and satisfactory oncologic outcomes.

Comparison of short-term and oncologic outcomes of robotic and laparoscopic resection for mid- and distal rectal cancer

Laparoscopic rectal resection with total mesorectal excision is a technically challenging procedure, and there are limitations in conventional laparoscopy. A surgical robotic system may help to overcome some of the limitations. This study aimed to compare the short-term operative as well as oncologic outcomes of laparoscopic and robotic rectal resection. This study was based on a prospectively collected database of patients with mid- to distal rectal cancer (up to 12cm from the anal verge) undergoing either laparoscopic or robotic low anterior resection from January 2008 to June 2015. Data on patient demographics, intraoperative parameters and short-term outcomes were analyzed. Patient survival and recurrence were also compared. During the study period, 171 and 220 consecutive patients underwent laparoscopic and robotic rectal resection, respectively. The median age was 65years (range 23-96). The median tumor distance was 8 and 7cm from the anal verge in the laparoscopic and robotic groups, respectively (p=0.06). Significantly more male patients and more patients with comorbidities and preoperative radiation underwent robotic surgery. The median operating time for robotic resection was significantly longer, 260 versus 225min (p<0.001). Conversion rates of laparoscopic and robotic resection were 3.5 and 0.8%, respectively (p=0.308). The median hospital stay was 6days in both groups (p=0.29). There was no difference in the overall complication rate, but the incidence of urinary retention was significantly less in the robotic group (4.1 vs. 10.5%, p=0.024). With a median follow-up of 31months, there was no difference in local recurrence, overall survival and disease-specific survival between the two groups. In the treatment of mid- to low rectal cancer, robotic resection can achieve operative results and oncologic outcomes comparable to laparoscopic resection. The postoperative urinary retention rate is lower following robotic surgery.

Simultaneous robotic low anterior resection and prostatectomy for adenocarcinoma of rectum and prostate: initial case report.

BackgroundWe report a case of synchronous rectal and prostate cancer treated successfully with simultaneous da Vinci robotic-assisted low anterior resection of the rectum and robotic-assisted laparoscopic radical prostatectomy to address both cancers.Case presentationRecently, minimally invasive surgical techniques using da Vinci robot® system (Intuitive Surgical, Sunnyvale, USA) were introduced as curative surgical modality of prostate and rectal malignancies. Herein, we report an initial case of simultaneous robotic low anterior resection and robotic prostatectomy for adenocarcinoma of rectum and prostate sharing a considerable number of port sites.ConclusionSimultaneous robotic-assisted low anterior resection could be performed with robotic-assisted radical prostatectomy safely and effectively in synchronous rectal and prostate cancer.

Laparoscopic versus robotic colectomy: a national surgical quality improvement project analysis

Robotic colorectal surgery is being increasingly adopted. Our objective was to compare early postoperative outcomes between robotic and laparoscopic colectomy in a nationally representative sample. The American College of Surgeons National Surgical Quality Improvement Project Colectomy Targeted Dataset from 2012 to 2014 was used for this study. Adult patients undergoing elective colectomy with an anastomosis were included. Patients were stratified based on location of colorectal resection (low anterior resection (LAR), left-sided resection, or right-sided resection). Bivariate data analysis was performed, and logistic regression modeling was conducted to calculate risk-adjusted 30-day outcomes. There were a total of 25,998 laparoscopic colectomies (30% LAR's, 45% left-sided, and 25% right-sided) and 1484 robotic colectomies (54% LAR's, 28% left-sided, and 18% right-sided). The risk-adjusted overall morbidity, serious morbidity, and mortality were similar between laparoscopic and robotic approaches in all anastomotic groups. Patients undergoing robotic LAR had a lower conversion rate (OR 0.47, 95% CI 1.20-1.76) and postoperative sepsis rate (OR 0.49, 95% CI 0.29-0.85) but a higher rate of diverting ostomies (OR 1.45, 95% CI 1.20-1.76). Robotic right-sided colectomies had significantly lower conversion rates (OR 0.58, 95% CI 0.34-0.96). Robotic colectomy in all groups was associated with a longer operative time (by 40min) and a decreased length of stay (by 0.5days). In a nationally representative sample comparing laparoscopic and robotic colectomies, the overall morbidity, serious morbidity, and mortality between groups are similar while length of stay was shorter by 0.5days in the robotic colectomy group. Robotic LAR was associated with lower conversion rates and lower septic complications. However, robotic LAR is also associated with a significantly higher rate of diverting ostomy. The reason for this relationship is unclear. Surgeon factors, patient factors, and technical factors should be considered in future studies.

Robotic low anterior resection

The surgical robot is an ideal instrument for use in the pelvis and on the rectum. A low anterior resection can be performed using a totally robotic technique or a laparoscopic hybrid approach. The pre-operative planning for a robotic approach is similar to that of a laparoscopic or traditional open approach. The robotic approach is ideally suited for patients with low or middle rectum pathology, and the only absolute contraindication is inability to tolerate pneumoperitoneum. The operation is performed using four robotic trocar sites, as well as camera and assistant ports. The entire operation can be performed without repositioning the robotic console. There are few potential complications unique to the robotic approach, and the outcomes of robotic low anterior resection appear similar to that of the laparoscopic approach. This article describes the technique of a robotic low anterior resection, including splenic flexure mobilization, total mesorectal excision and specimen extraction, and well the peri-operative management.

Minimally invasive surgery and sphincter preservation in rectal cancer

BackgroundNational adoption of sphincter-preserving surgery (SPS) and minimally invasive surgery (MIS) has not been well documented. We examined national trends in use of SPS and MIS. Materials and methodsThe National Inpatient Sample was used to evaluate open, laparoscopic, and robotic low anterior resection (LAR) or abdominoperineal resection (APR) for patients undergoing rectal cancer surgery from 2009 to 2011. Trends in SPS and MIS were stratified by hospital volume. Propensity score matching was used. ResultsA total of 24,999 (62.0%) patients underwent LAR, and 15,288 (38.0%) underwent APR from 2009 to 2011. A total of 22,310 (89.2%) LARs were open and 2689 (10.8%) MIS. A total of 11,600 (75.9%) APRs were open and 3688 (24.1%) MIS. Most procedures were at high-volume centers. In propensity-matched analysis, length of stay for LAR was longer in open surgery (6 versus 5 d; P = 0.01); in APR, MIS patients were less likely to have wound, infectious, urinary, and gastrointestinal complications, and length of stay was shorter (6 versus 8 d; P < 0.01). ConclusionsSPS and MIS rates have increased nationally, especially in high-volume centers. In addition, the perioperative benefits seen in randomized clinical trials are maintained in a national database. Further studies should focus on understanding differences in survival and oncologic outcomes with MIS techniques.

Robotic Versus Laparoscopic Resection for Mid and Low Rectal Cancers.

Background and Objectives:The current study was conducted to determine whether robotic low anterior resection (RLAR) has real benefit over laparoscopic low anterior resection (LLAR) in terms of surgical and early oncologic outcomes.Methods:We retrospectively analyzed data from 35 RLARs and 28 LLARs, performed for mid and low rectal cancers, from January 2013 through June 2015.Results:A total of 63 patients were included in the study. All surgeries were performed successfully. The clinicopathologic characteristics were similar between the 2 groups. Compared with the laparoscopic group, the robotic group had less intraoperative blood loss (165 vs. 120 mL; P < .05) and higher mean operative time (252 vs. 208 min; P < .05). No significant differences were observed in the time to flatus passage, length of hospital stay, and postoperative morbidity. Pathological examination of total mesorectal excision (TME) specimens showed that both circumferential resection margin and transverse (proximal and distal) margins were negative in the RLAR group. However, 1 patient each had positive circumferential resection margin and positive distal transverse margin in the LLAR group. The mean number of harvested lymph nodes was 27 in the RLAR group and 23 in the LLAR group.Conclusions:In our study, short-term outcomes of robotic surgery for mid and low rectal cancers were similar to those of laparoscopic surgery. The quality of TME specimens was better in the patients who underwent robotic surgery. However, the longer operative time was a limitation of robotic surgery.

Emerging and Evolving Technology in Colon and Rectal Surgery.

Minimally invasive surgery has changed the way we manage many colon and rectal pathologies. Multiple techniques, from straight laparoscopic procedures, to hand-assisted and single-port techniques are available, requiring surgeons to go through various learning curves. Robotic surgery is a relatively novel technique in general surgery which appears to hold most promise for rectal resection. Laparoscopic rectal procedures are difficult, and even in experienced hands, conversion rates are around 17%. Robotic surgery may be a point of difference in these cases, despite a long learning curve and higher costs. This article will describe the role of robotics in colorectal surgery. Room set up, port placement, and docking strategies will be described for common procedures, with emphasis on a hybrid robotic low anterior resection.

Long-term Oncologic Outcomes of Robotic Low Anterior Resection for Rectal Cancer

The aim of this study is to evaluate long-term oncologic outcomes of robotic surgery for rectal cancer compared with laparoscopic surgery at a single institution. Robotic surgery is regarded as a new modality to surpass the technical limitations of conventional surgery. Short-term outcomes of robotic surgery for rectal cancer were acceptable in previous reports. However, evidence of long-term feasibility and oncologic safety is required. Between April 2006 and August 2011, 217 patients who underwent minimally invasive surgery for rectal cancer with stage I-III disease were enrolled prospectively (robot, n = 133; laparoscopy, n = 84). Median follow-up period was 58 months (range, 4-80 months). Perioperative clinicopathologic outcomes, morbidities, 5-year survival rates, prognostic factors, and cost were evaluated. Perioperative clinicopathologic outcomes demonstrated no significant differences except for the conversion rate and length of hospital stay. The 5-year overall survival rate was 92.8% in robotic, and 93.5% in laparoscopic surgical procedures (P = 0.829). The 5-year disease-free survival rate was 81.9% and 78.7%, respectively (P = 0.547). Local recurrence was similar: 2.3% and 1.2% (P = 0.649). According to the univariate analysis, this type of surgical approach was not a prognostic factor for long-term survival. The patient's mean payment for robotic surgery was approximately 2.34 times higher than laparoscopic surgery. No significant differences were found in the 5-year overall, disease-free survival and local recurrence rates between robotic and laparoscopic surgical procedures. We concluded that robotic surgery for rectal cancer failed to offer any oncologic or clinical benefits as compared with laparoscopy despite an increased cost.

Is the Learning Curve of Robotic Low Anterior Resection Shorter Than Laparoscopic Low Anterior Resection for Rectal Cancer?

As robotic surgery was developed with ergonomic designs, there are expectations that the technical advantages of robotic surgery can shorten the learning curve. However, there is no comparative study, so far, to evaluate the learning curve between robotic and laparoscopic rectal cancer surgeries. Therefore, the aim of this study is to compare the learning curve of robotic low anterior resection (LAR) with laparoscopic LAR for rectal cancer.Patients who underwent robotic or laparoscopic LAR by a single surgeon were compared retrospectively (robot n = 89 vs laparoscopy n = 89). Cumulative sum (CUSUM) was used to evaluate the learning curve. The patients were divided into phase 1 (initial learning curve period) and phase 2 (post-learning curve period). The perioperative clinicopathologic characteristics were compared by phases and surgical procedures.According to CUSUM, the learning curve of robotic LAR was the 44th case and laparoscopic LAR was the 41st case. The learning phases were divided as follows: phase 1 (cases 1–41) versus phase 2 (cases 42–89) in the laparoscopic group, and phase 1 (cases 1–44) versus phase 2 (cases 45–89) in the robotic group. Comparison between phase 1 and phase 2 in each type of surgery showed no significant difference for the perioperative outcomes. Comparison between robotic and laparoscopic surgeries in each phase showed similar perioperative results. Pathologic outcomes were not significantly different in both procedures and phases.The learning curve of robotic LAR for rectal cancer was similar to laparoscopic LAR, and the clinicopathologic outcomes were similar in both the procedures.

461. Robotic assisted versus laparoscopic resection for rectal cancer: Short-term outcomes from early experience from consecutive patients

Purpose: Robotic surgery has been advocated for the radical excision of rectal cancer. The aim of this study is to compare short-term outcomes and surgical quality of robot-assisted and laparoscopic total mesorectal excision (TME) in patients with rectal cancer.

462. Robotic splenic flexure mobilization is not difficult anymore: ‘Inferior penetration method’

462. Robotic splenic flexure mobilization is not difficult anymore: ‘Inferior penetration method’

Multidimensional analyses of the learning curve of robotic low anterior resection for rectal cancer: 3-phase learning process comparison

Robotic surgery has advantages to perform rectal cancer by its ergonomic designs and advanced technologies. However, it was uncertain whether these core robotic technologies could shorten the learning curve. The aim of this study is to investigate the learning curve of robotic rectal cancer surgery and to compare the learning curve phases with respect to perioperative clinicopathologic outcomes. From April 2006 to August 2011, a total of 130 consecutive patients who were diagnosed with rectal cancer underwent a robotic low anterior resection (LAR) using the hybrid technique by a single surgeon at Severance Hospital. The moving average method and the cumulative sum (CUSUM) were used to analyze the learning curve. The risk-adjusted CUSUM (RA-CUSUM) analysis was used to evaluate the points, which showed completion of surgical procedures in terms of R1 resection, conversion, postoperative complications, harvested lymph nodes less than 12, and local recurrence. Perioperative clinical outcomes and pathologic results were compared among the learning curve phases. According to the CUSUM, the learning curve was divided into three phases: phase 1 [the initial learning period (1st-44th case), n = 44], phase 2 [the competent period (45th-78th case), n = 34], and phase 3 [the challenging period (79th-130th case), n = 52]. RA-CUSUM showed the minimum value at the 75th case, which suggested technical competence to satisfy feasible perioperative outcomes. The total operation time tended to decrease after phase 1 and so did the surgeon console time and docking time. Postoperative complications and pathologic outcomes were not significantly different among the learning phases. The learning curve of robotic LAR consisted of three phases. The primary technical competence was achieved at phase 1 of the 44th case according to the CUSUM. The technical completion to assure feasible perioperative outcomes was achieved at phase 2 at the 75th case by the RA-CUSUM method.