Minimally Invasive Ivor Lewis Esophagectomy: Description of a Learning Curve Luis F Tapias,
MD,
Christopher R Morse,
MD, FACS
Minimally invasive Ivor Lewis esophagectomy (MIE) is gaining popularity for the treatment of esophageal cancer. However, as it is a technically demanding operation, a learning curve should be defined to guide training and allow implementation at institutions not currently using this technique. STUDY DESIGN: Our study included a retrospective series of the first 80 consecutive patients undergoing MIE by a single surgeon with advanced training in minimally invasive esophageal surgery in independent practice at a high-volume tertiary center. Patients were stratified into 2 groups of 40 patients, with chronological order defining early and late experiences. Primary end points included conversion to open procedure, surgical time, blood loss, chest drainage duration, time to oral intake, hospital stay, postoperative morbidity, and mortality. The cumulative sum methodology was used and analyzed by visually inspecting the plots. RESULTS: Conversion to open procedure occurred in 2 (5%) patients in the early group and none in the late group (p ¼ 0.49). Comparing early vs late experience, mean surgical time was 364 vs 316 minutes (p < 0.01), estimated blood loss was 205 vs 176 mL (p ¼ 0.14), median hospital stay was 7 vs 6 days (p < 0.01), and morbidity was observed in 16 (40%) and 14 (35%) patients (p ¼ 0.82), respectively. There were no anastomotic leaks or 30-day mortality. Cumulative sum plots showed decreasing surgical time after patient 54 (plateau after patient 31), decreasing chest tube duration after patients 38 and 33, sooner oral intake after patient 35, and decreased hospital stay after patient 33. CONCLUSIONS: Improved operative and perioperative parameters for MIE were observed in the last 40 patients when compared with the first 40 patients. A reasonable learning curve for MIE would require the operation and perioperative care of 35 to 40 patients. (J Am Coll Surg 2014;218:1130e1140. 2014 by the American College of Surgeons)
BACKGROUND:
Esophagectomy remains a mainstay in the treatment of early or locally advanced esophageal cancer. Historically, esophagectomy has been associated with high rates of morbidity and mortality. In 2002, an analysis of the National Medicare claims database and the Nationwide Inpatient Sample estimated mortality rates for esophagectomy ranging between 8.1% and 23.1% across the United States and showed a negative association with hospital volume.1 In 2009, an outcomes analysis of 2,315 patients derived from the Society of Thoracic Surgeons’ Disclosure Information: Nothing to disclose. Presented at the New England Surgical Society 94th Annual Meeting, Hartford, CT, September 2013. Received October 15, 2013; Revised February 6, 2014; Accepted February 12, 2014. From the Division of Thoracic Surgery, Massachusetts General Hospital, Boston, MA. Correspondence address: Christopher R Morse, MD, FACS, Division of Thoracic Surgery, Massachusetts General Hospital, 55 Fruit St, Blake 1570, Boston, MA 02114. email: [email protected]
ª 2014 by the American College of Surgeons Published by Elsevier Inc.
General Thoracic Database estimated a hospital mortality rate of 2.7% and postoperative major morbidity rate of 24% among a selected group of 73 participating centers.2 Given these high rates of postoperative morbidity and mortality, minimally invasive techniques for esophagectomy are gaining popularity in an attempt to improve outcomes. The largest series to date was reported by Luketich and colleagues in 2012,3 who accumulated experience with 1,011 patients, including 530 patients undergoing minimally invasive Ivor Lewis esophagectomy (MIE). They reported postoperative major morbidity ranging between 2% and 5% for specific complications, and mortality was reported at 0.9%. Although these are the results of a high-volume, highly experienced center, they support the pursuit of a minimally invasive technique as the routine approach to esophagectomy. However, for MIE to continue gaining popularity and widespread application, a learning curve needs to be defined to guide training. Cumulative sum (CUSUM) analysis has been used for decades to analyze data in the medical field,4 including
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Tapias and Morse
Abbreviations and Acronyms
CUSUM EEA IQR MIE
¼ ¼ ¼ ¼
cumulative sum end to end anastomosis interquartile range minimally invasive Ivor Lewis esophagectomy
the learning curves of surgical procedures. This analysis transforms raw data into the running total of data deviations from their group mean, enabling the visualization of trends in a dataset not discernable with other approaches. Recently, the CUSUM analysis has been applied to evaluation of the learning curve of minimally invasive surgical procedures in the field of colorectal, bariatric, and benign esophageal surgery.5-7 The learning curves of open esophagectomy,8 hybrid esophagectomy (when either the abdominal or thoracic portion of the procedure was performed using a minimally invasive technique),9-11 3-field minimally invasive esophagectomy12,13 or Ivor Lewis esophagectomies using hand-assisted laparoscopy, and a minithoracotomy with rib spreading during the creation of the intrathoracic anastomosis14 have been studied in the past. To the best of our knowledge, there has been no publication addressing the learning curve of a totally minimally invasive Ivor Lewis esophagectomy. Previous reports on other techniques for a less invasive esophagectomy have focused on postoperative morbidity and mortality as outcomes, or evaluated intraoperative variables, such as surgical time and conversion to open rates, to define the learning curves, assuming that these variables alone indicate higher proficiency with the technique.9-14 These studies have failed to explore important parameters in the postoperative care of patients undergoing MIE, such as management of chest tubes and nasogastric drainage, and initiation of oral intake, among others, which can be important indicators of a learning curve as well. This study aims to analyze the learning curve for MIE for a single surgeon with advanced training in minimally invasive esophageal surgery after entering independent practice at a tertiary academic center with a high volume of esophageal surgical patients. These results are of interest as they provide a preliminary assessment of the learning curve associated with MIE to guide training programs or the transition period in centers willing to implement this technique.
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minimally invasive esophageal surgery to assess the learning curve during this transition period. The study population included 80 consecutive patients undergoing MIE at the Massachusetts General Hospital between November 2007 and October 2012 by this surgeon only. These patients represented 75.5% of the total esophagectomy case load for this surgeon and approximately 27.8% of all esophagectomies at this institution during the study period. The number of MIEs per year of experience is shown in Figure 1 in relation to the number of open esophagectomies done by this surgeon during the study period. Patients were selected to undergo an open esophagectomy based on a number of factors, including previous abdominal/chest operations and body habitus, among others. Upper endoscopy was performed on all patients, after which a diagnosis of esophageal cancer was confirmed. All patients were evaluated with CT of the chest, abdomen, and pelvis. Most patients underwent staging with positron emission tomography and endoscopic ultrasound, if feasible. Patients were typically evaluated in a multidisciplinary approach. The current study included both patients who received and did not receive neoadjuvant therapy.15 In general, patients with resectable T2N0 or greater disease were considered for neoadjuvant therapy. The chemotherapy regimen was platinum based in most patients, cisplatin and 5-fluoroacil were preferred. Intensity-modulated radiation was given to achieve a preoperative dose of 50.4 Gy. Demographics, preoperative and intraoperative data, as well as outcomes measures, were recorded.
METHODS Patients We limited this study to the first 5 years of independent practice of a single surgeon with advanced training in
Figure 1. Number of esophagectomies performed stratified by year of experience. Gray bar, open; black bar, minimally invasive Ivor Lewis esophagectomy.
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Surgical technique Surgery was typically performed 6 weeks after the last chemotherapy or radiotherapy session. The technique of MIE has been described in detail elsewhere,16 and is the same one used by us, with minor modifications.17 Briefly, 5 laparoscopic ports are placed for the abdominal portion of the procedure. If no metastatic disease is found on initial inspection of the abdominal cavity, then the gastrohepatic ligament is opened and the right crus and the inferior and anterior aspects of the esophagus are mobilized. Attention is then turned to the greater curvature of the stomach, opening the greater omentum, taking the short gastric vessels, and preserving the right gastroepiploic artery. Retrogastric attachments are taken down, and the left gastric vessels are divided with a stapler. A sixth laparoscopic port is placed in the right lower quadrant and the gastric conduit is created. No pyloric drainage procedure was performed. All patients received a jejunostomy either preoperatively or during the same procedure. The patient is then turned to the left lateral decubitus position for the chest portion of the procedure. Four thoracoscopy ports are used. Mobilization of the esophagus begins along the posterior aspect of the right hilum, and the azygos vein is divided. All paraesophageal lymph nodes and those in mediastinal station 7 are dissected entirely. The lateral aspect of the esophagus is dissected, and the gastric conduit is mobilized into the chest. Proper orientation of the gastric conduit is maintained. The esophagus is divided and the margins checked by frozen-section pathology. The anastomosis is preferably completed with a 28-mm end to end anastomosis (EEA) stapler (Covidien), and 2 purse-string sutures are used to secure the anvil of the stapler in the esophagus. The EEA stapler is introduced by enlarging the posterior, inferior incision and through a gastrotomy in the gastric fundus. The anastomosis is constructed, and the tip of the gastric fundus is removed using a linear stapler. The anastomosis suture line is not covered or reinforced. Two chest tubes are left in the pleural space at the end of the procedure: a 28F Argyle-type straight chest tube (Covidien) and a 19F Blake drain (Ethicon). Postoperative care Epidural analgesia is avoided in patients undergoing MIE. Postoperative pain control is achieved by a combination of intercostal nerve blocks during the operation, intravenous patient-controlled analgesia with opioids, and ketorolac. Routine extubation in the operating room is attempted in all patients. Patients routinely spend the first night in the ICU. Nasogastric tubes are left in place until there is return of bowel function (ie, passage
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of flatus or bowel movement) and remain in place until a postoperative barium swallow. Argyle-type chest tubes are typically removed on postoperative day 3 after tube feedings are started and there is no evidence of air or chyle leak. Blake drains (Ethicon) are typically removed after a routine barium swallow demonstrates no anastomotic leak, taking into account the same general criteria for chest tubes. Chest tubes are not left in place after resumption of a diet. Barium swallows are routinely ordered around the 5th or 6th postoperative day. If no anastomotic leak or delayed gastric emptying is demonstrated, the patient is started on a staged esophageal diet. Study end points The primary end points for this study were the rate of conversion to open procedure, surgical time, estimated blood loss, duration of chest drainage, time to initiation of oral intake, hospital length of stay, and postoperative morbidity and mortality. Total surgical time was defined as the time in minutes from skin incision to final skin closure. Abdominal surgical time was defined as the time from skin incision to reintubation with a doublelumen endotracheal tube. Chest surgical time was defined as the time from reintubation to final skin closure. Estimated blood loss was recorded after reconciling surgical and anesthesia records. Duration of chest drainage was recorded independently for each of the 2 chest tubes. Postoperative mortality was defined as deaths occurring during the same hospital stay or within the next 30 and 90 days after surgery. Anastomotic stricture was defined as the need for 2 or more postoperative dilations of the anastomosis. Statistical analysis The first 40 patients who underwent MIE represented the early-experience group (November 2007eDecember 2010) and the last 40 patients represented the lateexperience group (January 2011eOctober 2012). Data from the patients were analyzed using the statistical software Stata/SE 10.1 (StataCorp). Variables were analyzed as proportions, means, or medians with variability estimates in the form of SD and interquartile ranges (IQR), as appropriate. Fisher’s exact test was used to compare the distribution of categorical variables between groups. Continuous variables were analyzed using Student’s t-test or Wilcoxon rank sum test. Statistical significance was defined as a 2-sided p value 0.99 >0.99 0.62 0.48 0.77 >0.99 >0.99 0.49
87.1 18.2 75.7 21.8
96.5 15.9 79.6 20.7
7 (17.5) 4 (10.0)
8 (20.0) 3 (7.5)
>0.99 >0.99
40 (100) 38 (95) 37 (92.5)
40 (100) 38 (95) 21 (52.5)
>0.99 0.99 0.18
0.34 0.36 0.71 0.71 >0.99 >0.99 >0.99 0.43
*Excluding 1 patient with gastrointestinal stromal tumor. y Radiofrequency ablation. GIST, gastrointestinal stromal tumor; MIE, minimally invasive Ivor Lewis esophagectomy.
Postoperative care Results for postoperative care parameters are shown in Table 4. Intensive care unit length of stay was seen to increase significantly from a median of 1 day (IQR, 1e1 day) in the early-experience group to 1 day (IQR, 1e3 days) in the late-experience group (p ¼ 0.02). For the management of tubes and drains, there were no significant differences in the duration of nasogastric drainage between groups at a median of 5 days postoperatively. However, there were significant differences in the duration of chest drainage: Argyle-type (Covidien) and Blake (Ethicon) chest tubes were both pulled out at a median of 6 days in the early-experience groups, and they were removed at a median of 3 and 5 days, respectively, in the late-experience group of patients. A contrast swallow study was obtained routinely in all patients; however, it was obtained significantly sooner, by 1 day, in patients in the late-experience group (postoperative day 5), when compared with the early-experience group. There was no significant difference in the frequency of delayed gastric emptying between groups, as reported on this contrast study. Accordingly, oral intake with a staged esophageal diet was started significantly sooner in patients in the late-experience group, as seen in Table 4.
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Table 3.
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Intraoperative Variables and Pathologic Examination of Surgical Specimens
Variables
First 40 MIE
Last 40 MIE
Conversion to open, n (%) Jejunostomy placement at time of MIE, n (%) Pyloric drainage procedure, n (%) Size of EEA stapler for anastomosis, mm, n (%) 25 28 Total surgical time, min, median (IQR) Abdomen surgical time, min, median (IQR) Chest surgical time, min, median (IQR) Estimated blood loss, mL, median (IQR) Intraoperative transfusion, n (%) Extubated in operating room, n (%) Tumor location, n (%) Mid-esophagus Lower esophagus EGJ Pathologic staging, n (%)y Complete response 0 IA IB IIA IIB IIIA IIIB IIIC IV R0 resection, n (%) No. of harvested lymph nodes, median (IQR)y
2 (5.0) 37 (92.5) 0 (0)
0 (0) 33 (82.5) 0 (0)
p Value
0.49 0.31 *
>0.99 2 38 361.5 201 164 200 2 40
(5.0) (95.0) (302e429) (158e258) (127e204) (150e300) (5.0) (100)
1 (2.5) 29 (72.5) 10 (25.0) 5 1 13 3 3 6 6 2 0 0 40 19
(12.8) (2.6) (33.3) (7.7) (7.7) (15.4) (15.4) (5.1) (0) (0) (100) (12e34)
3 37 317 163.5 141 200 0 40
(7.5) (92.5) (255e368) (132e202) (114e184) (50e300) (0) (100)
1 (2.5) 17 (42.5) 22 (55.0) 7 0 8 4 0 13 4 3 1 0 40 21.5
(17.5) (0) (20.0) (10.0) (0) (32.5) (10.0) (7.5) (2.5) (0) (100) (11e30)
0.99
3
7.5
2
5.0
>0.99
*
*Unable to derive a p value for this comparison because all patients in both groups either presented or did not present this characteristic simultaneously.
which can negatively impact outcomes.18 Because of this, there has been increasing interest in adopting minimally invasive approaches to esophagectomy in an attempt to improve early postoperative outcomes. Minimally invasive esophagectomy has the potential for an easier postoperative recovery with fewer cardiopulmonary complications when compared with open approaches.19 In addition, enhanced visualization of abdominal and mediastinal structures by means of a minimally invasive, video-assisted approach might facilitate intraoperative steps, reduce injury to neighboring structures, improve lymph node harvest, and decrease blood loss.20 To support these notions, multiple small retrospective series have been published examining the outcomes of MIE.13 However, the largest series to date was published by Luketich and colleagues3 in 2012, and included 530 patients undergoing MIE. In this report, the rate of conversion to open procedure was 4%, median postoperative length of stay was 7 days, and median ICU length of stay was 2 days; vocal cord paresis occurred in 1% and anastomotic leak requiring intervention was observed in 4%. Mortality at 30 days was reported at an outstandingly low rate of 0.9%. These excellent results support the pursuit of MIE as the routine approach to esophagectomy. In addition, retrospective series have performed direct comparisons between MIE and open esophagectomy,19 showing a reduction in postoperative pulmonary complications in patients undergoing MIE, as well as shorter ICU and hospital lengths of stay. The benefits of a minimally invasive approach to esophagectomy were confirmed in a small randomized controlled trial published by Biere and colleagues20 in 2012, after comparing 59 patients randomly assigned to undergo a minimally invasive esophagectomy (which represented a 3-field McKeown-type esophagectomy in two thirds of
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Figure 2. Cumulative sum (CUSUM) plot for surgical time. Cumulative sum in minutes on the vertical axis is plotted against patient number on the horizontal axis. (A) Overall surgical time; (B) surgical time, abdominal stage; and (C) surgical time, thoracic stage.
patients, with the thoracoscopic portion being performed in the prone position) with 56 patients assigned to open esophagectomy. This trial showed a considerable reduction in postoperative pneumonia, hospital length of stay, postoperative pain scores, operative blood loss, and vocal cord paralysis, as well as improved quality of life at 6 weeks after surgery. Although larger prospective multi-institutional trials are awaited, it is not unreasonable to foresee MIE as the surgical approach of choice for the treatment of esophageal cancer in the near future. Despite its benefits, MIE is probably one of the most technically demanding operations in the field of general thoracic surgery and requires training in advanced laparoscopic and thoracoscopic surgical techniques. For MIE to continue to gain popularity and widespread applicability, formal surgical training in the technique to perform MIE
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should take place. Therefore, its learning curve needs to be defined to guide the training of residents, fellows, and thoracic surgeons who are looking to transition in their practice. As shown, patients in both groups were similar in terms of demographics, baseline comorbid conditions, esophageal pathology, and rates of neoadjuvant therapy, with some exceptions. More patients reported a smoking history in the late-experience group. This difference did not translate to a significantly higher proportion of patients having a diagnosis of COPD or worsened pulmonary function. Additionally, endoscopic ultrasound was not technically feasible in a higher proportion of patients in the late group due to a higher percentage of obstructing masses. This finding might have affected accurate clinical staging. However, most patients were classified as stages IIB or IIIA, and received neoadjuvant therapy. Finally, there was a shift in tumor location from a predominant lower esophageal location in the early experience to a predominant esophagogastric junction location in the late-experience group. We think this is a result of chance alone. There was not an intended selection bias toward operating more frequently on tumors located in the esophagogastric junction by means of MIE, as MIE is equally suitable for the surgical treatment of tumors in either location. These observed differences alone do not explain the results obtained in intraoperative and postoperative variables in the current study. When examining intraoperative variables, we observed similar rates of conversion to open procedure between the early- and late-experience groups, although the only 2 conversions were observed during the first 40 MIEs (patient numbers 15 and 29). Surgical time was seen to improve significantly in the late-experience group by a median of approximately 44 minutes. Shorter surgical times are a surrogate for proficiency with the technique and systematization of the operation, however, longer surgical times might also represent more challenging cases. Oncologic outcomes were comparable, as all patients underwent R0 resection and the number of lymph nodes harvested was similar and comparable with published series.3 The evaluation of the postoperative period revealed interesting findings. Intensive care unit length of stay increased substantially in the late-experience group. However, this finding did not translate into an overall prolonged hospital length of stay; in fact, total length of stay decreased by a median of 1 day in the last 40 patients and there were no differences in the disposition of patients at discharge. Taken together, this likely represents delays in the transfer of patients from the ICU to the floor, possibly due to bed availability issues.
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Figure 3. Cumulative sum (CUSUM) plot for postoperative care parameters. Cumulative sum in days on the vertical axis is plotted against patient number on the horizontal axis. (A) Duration of Argyle-type chest tube; (B) duration of Blake-type chest tube; (C) initiation of oral intake; and (D) length of hospital stay.
A very important aspect in the postoperative care of patients after esophagectomy is the management of drains and chest tubes, as well as the careful resumption of oral intake. We observed a very significant reduction in the duration of rigid Argyle chest tubes by a median of 3 days in the late-experience group, halving the duration seen in patients operated on during the early experience. This was also true for Blake chest tubes, which reduced their duration in the pleural space by a median of 1 day. A shorter duration of chest drainage can translate into reduced postoperative pain, improved patient comfort, and easier and earlier mobilization. A shorter duration of chest drainage can also represent a higher comfort level by the surgeon with the potential for thoracic duct leaks as well as anastomotic complications. Likely, this is the same reason we observed earlier ordering of routine contrast swallow studies in the lateexperience group and, as a consequence, earlier initiation of oral intake. Although this might not make a significant difference from a nutritional perspective because all patients were routinely started on enteral nutritional support through a jejunostomy on postoperative day 2, this can result in increased comfort to the patient as well as in encouragement during the recovery phase. To our knowledge, this is the first time that these postoperative care variables have been analyzed in detail in MIE patients. To have a better understanding of surgeon’s performance during our experience with MIE, we applied the CUSUM methodology to identify the moment along the entire experience when the outcomes of interest started
to improve significantly. As seen in Figures 2 and 3, surgical time, duration of chest drainage, re-initiation of oral intake, and hospital length of stay saw improved results after approximately 35 to 40 operations. This is an interesting finding that suggests that the number of patients needed to operate and take care of perioperatively to achieve improving results in these parameters is at least 35 to 40. Our findings are in concordance with previous recommendations provided by experts. In 2008, the Association of Upper Gastrointestinal Surgeons and the Association of Laparoscopic Surgeons of Great Britain and Ireland issued a consensus document with recommendations for the development and practice of MIE,21 stating that the learning curve for MIE is thought to be between 20 and 50 operations. Additionally, our findings are similar when compared with those derived from the evaluation of the learning curve of other minimally invasive techniques with esophagectomy, including hybrid approaches, which have reported improving outcomes after 14 to 46 operations.9,11-14 Therefore, a reasonable learning curve for a completely minimally invasive Ivor Lewis esophagectomy can require the operation and perioperative care of 35 to 40 patients. A possible explanation for the faster progression during the postoperative period observed in the late-experience group is that the surgeon became more comfortable with postoperative care as he gained experience with the operation, especially during this critical period of transition between advanced fellowship training and independent practice with a surgical technique that was being implemented at an academic center with extensive experience
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with esophageal surgical pathology. This is a fundamental part of the learning process. Some of these findings might be the reflection of a higher confidence level with technical aspects of the operation, such as minimal bleeding, the integrity of the intrathoracic anastomosis or the proper orientation and sizing of the gastric conduit. As these technical intraoperative steps improve and become more fluent and less flawed, they allow for faster progression during the postoperative period. Therefore, proper surgical technique is a sine qua non for being more aggressive with the removal of tubes and drains and the resumption of a diet during the postoperative period of MIE without resulting in increased morbidity. There are limitations to this study. First, it represents the learning curve of a single surgeon and as expected, it can change from surgeon to surgeon, depending on previous training and inherent skills. Additionally, we report our experience with 80 patients, and sample size might have contributed to statistical limitations. Also, as very well expressed by Sutton and colleagues,8 the learning curve described simply might not represent that of an individual surgeon, but that of an evolving specialist center in which the surgeon coordinates care. Changes in performance due to improvements in anesthesia, ancillary operating room staff, critical care, nursing, and others involved in the care of MIE patients are inseparable from those thought to be secondary to surgical performance. Therefore, our results might not be extrapolated in a different setting. The current study should prompt other centers and surgeons to evaluate their learning curve during implementation of MIE.
CONCLUSIONS We have described the learning curve for MIE for a single surgeon at a tertiary care center. For the first time in the MIE literature, we analyzed in detail the management of drains and tubes during the postoperative care. Additionally, we applied the CUSUM methodology to try to identify more precisely the moment along our experience when we observed improved results. Our findings suggest that the operation and perioperative care of 35 to 40 patients results in improving results in intraoperative and postoperative care parameters in subsequent patients. We expect that these results serve as support for development of curricula and specific requirements in thoracic surgery trainees. Author Contributions Study conception and design: Tapias, Morse Acquisition of data: Tapias, Morse Analysis and interpretation of data: Tapias, Morse
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Drafting of manuscript: Tapias, Morse Critical revision: Tapias, Morse REFERENCES 1. Birkmeyer JD, Siewers AE, Finlayson EV, et al. Hospital volume and surgical mortality in the United States. N Engl J Med 2002;346:1128e1137. 2. Wright CD, Kucharczuk JC, O’Brien SM, et al. Predictors of major morbidity and mortality after esophagectomy for esophageal cancer: a Society of Thoracic Surgeons General Thoracic Surgery Database risk adjustment model. J Thorac Cardiovasc Surg 2009;137:587e595. 3. Luketich JD, Pennathur A, Awais O, et al. Outcomes after minimally invasive esophagectomy: review of over 1000 patients. Ann Surg 2012;256:95e103. 4. Wohl H. The cusum plot: its utility in the analysis of clinical data. N Engl J Med 1977;296:1044e1045. 5. Bokhari MB, Patel CB, Ramos-Valadez DI, et al. Learning curve for robotic-assisted laparoscopic colorectal surgery. Surg Endosc 2011;25:855e860. 6. Buchs NC, Pugin F, Bucher P, et al. Learning curve for robotassisted Roux-en-Y gastric bypass. Surg Endosc 2012;26: 1116e1121. 7. Okrainec A, Ferri LE, Feldman LS, Fried GM. Defining the learning curve in laparoscopic paraesophageal hernia repair: a CUSUM analysis. Surg Endosc 2011;25:1083e1087. 8. Sutton DN, Wayman J, Griffin SM. Learning curve for oesophageal cancer surgery. Br J Surg 1998;85:1399e1402. 9. Osugi H, Takemura M, Higashino M, et al. Learning curve of video-assisted thoracoscopic esophagectomy and extensive lymphadenectomy for squamous cell cancer of the thoracic esophagus and results. Surg Endosc 2003;17: 515e519. 10. Ninomiya I, Osugi H, Tomizawa N, et al. Learning of thoracoscopic radical esophagectomy: how can the learning curve be made short and flat? Dis Esophagus 2010;23: 618e626. 11. Guo W, Zou YB, Ma Z, et al. One surgeon’s learning curve for video assisted thoracoscopic esophagectomy for esophageal cancer with the patient in lateral position: how many cases are needed to reach competence? Surg Endosc 2013;27: 1346e1352. 12. Song SY, Na KJ, Oh SG, Ahn BH. Learning curves of minimally invasive esophageal cancer surgery. Eur J Cardiothorac Surg 2009;35:689e693. 13. Lin J, Kang M, Chen C, et al. Thoracolaparoscopy oesophagectomy and extensive two-field lymphadenectomy for oesophageal cancer: introduction and teaching of a new technique in a high-volume centre. Eur J Cardiothorac Surg 2013;43:115e121. 14. Kunisaki C, Kosaka T, Ono HA, et al. Significance of thoracoscopy-assisted surgery with a minithoracotomy and hand-assisted laparoscopic surgery for esophageal cancer: the experience of a single surgeon. J Gastrointest Surg 2011;15: 1939e1951. 15. Tapias LF, Morse CR. Minimally invasive Ivor Lewis esophagectomy after induction therapy yields similar early outcomes to surgery alone. Innovations (Phila) 2011;6:331e336. 16. Pennathur A, Awais O, Luketich JD. Technique of minimally invasive Ivor Lewis esophagectomy. Ann Thorac Surg 2010; 89:S2159eS2162.
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17. Tapias LF, Morse CR. A preliminary experience with minimally invasive Ivor Lewis esophagectomy. Dis Esophagus 2012;25:449e455. 18. Tapias LF, Muniappan A, Wright CD, et al. Short and longterm outcomes after esophagectomy for cancer in elderly patients. Ann Thorac Surg 2013;95:1741e1748. 19. Sihag S, Wright CD, Wain JC, et al. Comparison of perioperative outcomes following open versus minimally invasive Ivor Lewis oesophagectomy at a single, high-volume centre. Eur J Cardiothorac Surg 2012;42:430e437.
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20. Biere SS, van Berge Henegouwen MI, Maas KW, et al. Minimally invasive versus open oesophagectomy for patients with oesophageal cancer: a multicentre, open-label, randomised controlled trial. Lancet 2012;379:1887e1892. 21. Association of Upper Gastrointestinal Surgeons, Association of Laparoscopic Surgeons. A Consensus View and Recommendations on the Development and Practice of Minimally Invasive Oesophagectomy. London: AUGIS; 2008. Available at: http://www.augis.org/pdf/MIO_Consensus.pdf. Accessed February 6, 2014.
MD,
Christopher R Morse,
MD, FACS
Minimally invasive Ivor Lewis esophagectomy (MIE) is gaining popularity for the treatment of esophageal cancer. However, as it is a technically demanding operation, a learning curve should be defined to guide training and allow implementation at institutions not currently using this technique. STUDY DESIGN: Our study included a retrospective series of the first 80 consecutive patients undergoing MIE by a single surgeon with advanced training in minimally invasive esophageal surgery in independent practice at a high-volume tertiary center. Patients were stratified into 2 groups of 40 patients, with chronological order defining early and late experiences. Primary end points included conversion to open procedure, surgical time, blood loss, chest drainage duration, time to oral intake, hospital stay, postoperative morbidity, and mortality. The cumulative sum methodology was used and analyzed by visually inspecting the plots. RESULTS: Conversion to open procedure occurred in 2 (5%) patients in the early group and none in the late group (p ¼ 0.49). Comparing early vs late experience, mean surgical time was 364 vs 316 minutes (p < 0.01), estimated blood loss was 205 vs 176 mL (p ¼ 0.14), median hospital stay was 7 vs 6 days (p < 0.01), and morbidity was observed in 16 (40%) and 14 (35%) patients (p ¼ 0.82), respectively. There were no anastomotic leaks or 30-day mortality. Cumulative sum plots showed decreasing surgical time after patient 54 (plateau after patient 31), decreasing chest tube duration after patients 38 and 33, sooner oral intake after patient 35, and decreased hospital stay after patient 33. CONCLUSIONS: Improved operative and perioperative parameters for MIE were observed in the last 40 patients when compared with the first 40 patients. A reasonable learning curve for MIE would require the operation and perioperative care of 35 to 40 patients. (J Am Coll Surg 2014;218:1130e1140. 2014 by the American College of Surgeons)
BACKGROUND:
Esophagectomy remains a mainstay in the treatment of early or locally advanced esophageal cancer. Historically, esophagectomy has been associated with high rates of morbidity and mortality. In 2002, an analysis of the National Medicare claims database and the Nationwide Inpatient Sample estimated mortality rates for esophagectomy ranging between 8.1% and 23.1% across the United States and showed a negative association with hospital volume.1 In 2009, an outcomes analysis of 2,315 patients derived from the Society of Thoracic Surgeons’ Disclosure Information: Nothing to disclose. Presented at the New England Surgical Society 94th Annual Meeting, Hartford, CT, September 2013. Received October 15, 2013; Revised February 6, 2014; Accepted February 12, 2014. From the Division of Thoracic Surgery, Massachusetts General Hospital, Boston, MA. Correspondence address: Christopher R Morse, MD, FACS, Division of Thoracic Surgery, Massachusetts General Hospital, 55 Fruit St, Blake 1570, Boston, MA 02114. email: [email protected]
ª 2014 by the American College of Surgeons Published by Elsevier Inc.
General Thoracic Database estimated a hospital mortality rate of 2.7% and postoperative major morbidity rate of 24% among a selected group of 73 participating centers.2 Given these high rates of postoperative morbidity and mortality, minimally invasive techniques for esophagectomy are gaining popularity in an attempt to improve outcomes. The largest series to date was reported by Luketich and colleagues in 2012,3 who accumulated experience with 1,011 patients, including 530 patients undergoing minimally invasive Ivor Lewis esophagectomy (MIE). They reported postoperative major morbidity ranging between 2% and 5% for specific complications, and mortality was reported at 0.9%. Although these are the results of a high-volume, highly experienced center, they support the pursuit of a minimally invasive technique as the routine approach to esophagectomy. However, for MIE to continue gaining popularity and widespread application, a learning curve needs to be defined to guide training. Cumulative sum (CUSUM) analysis has been used for decades to analyze data in the medical field,4 including
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Abbreviations and Acronyms
CUSUM EEA IQR MIE
¼ ¼ ¼ ¼
cumulative sum end to end anastomosis interquartile range minimally invasive Ivor Lewis esophagectomy
the learning curves of surgical procedures. This analysis transforms raw data into the running total of data deviations from their group mean, enabling the visualization of trends in a dataset not discernable with other approaches. Recently, the CUSUM analysis has been applied to evaluation of the learning curve of minimally invasive surgical procedures in the field of colorectal, bariatric, and benign esophageal surgery.5-7 The learning curves of open esophagectomy,8 hybrid esophagectomy (when either the abdominal or thoracic portion of the procedure was performed using a minimally invasive technique),9-11 3-field minimally invasive esophagectomy12,13 or Ivor Lewis esophagectomies using hand-assisted laparoscopy, and a minithoracotomy with rib spreading during the creation of the intrathoracic anastomosis14 have been studied in the past. To the best of our knowledge, there has been no publication addressing the learning curve of a totally minimally invasive Ivor Lewis esophagectomy. Previous reports on other techniques for a less invasive esophagectomy have focused on postoperative morbidity and mortality as outcomes, or evaluated intraoperative variables, such as surgical time and conversion to open rates, to define the learning curves, assuming that these variables alone indicate higher proficiency with the technique.9-14 These studies have failed to explore important parameters in the postoperative care of patients undergoing MIE, such as management of chest tubes and nasogastric drainage, and initiation of oral intake, among others, which can be important indicators of a learning curve as well. This study aims to analyze the learning curve for MIE for a single surgeon with advanced training in minimally invasive esophageal surgery after entering independent practice at a tertiary academic center with a high volume of esophageal surgical patients. These results are of interest as they provide a preliminary assessment of the learning curve associated with MIE to guide training programs or the transition period in centers willing to implement this technique.
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minimally invasive esophageal surgery to assess the learning curve during this transition period. The study population included 80 consecutive patients undergoing MIE at the Massachusetts General Hospital between November 2007 and October 2012 by this surgeon only. These patients represented 75.5% of the total esophagectomy case load for this surgeon and approximately 27.8% of all esophagectomies at this institution during the study period. The number of MIEs per year of experience is shown in Figure 1 in relation to the number of open esophagectomies done by this surgeon during the study period. Patients were selected to undergo an open esophagectomy based on a number of factors, including previous abdominal/chest operations and body habitus, among others. Upper endoscopy was performed on all patients, after which a diagnosis of esophageal cancer was confirmed. All patients were evaluated with CT of the chest, abdomen, and pelvis. Most patients underwent staging with positron emission tomography and endoscopic ultrasound, if feasible. Patients were typically evaluated in a multidisciplinary approach. The current study included both patients who received and did not receive neoadjuvant therapy.15 In general, patients with resectable T2N0 or greater disease were considered for neoadjuvant therapy. The chemotherapy regimen was platinum based in most patients, cisplatin and 5-fluoroacil were preferred. Intensity-modulated radiation was given to achieve a preoperative dose of 50.4 Gy. Demographics, preoperative and intraoperative data, as well as outcomes measures, were recorded.
METHODS Patients We limited this study to the first 5 years of independent practice of a single surgeon with advanced training in
Figure 1. Number of esophagectomies performed stratified by year of experience. Gray bar, open; black bar, minimally invasive Ivor Lewis esophagectomy.
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Surgical technique Surgery was typically performed 6 weeks after the last chemotherapy or radiotherapy session. The technique of MIE has been described in detail elsewhere,16 and is the same one used by us, with minor modifications.17 Briefly, 5 laparoscopic ports are placed for the abdominal portion of the procedure. If no metastatic disease is found on initial inspection of the abdominal cavity, then the gastrohepatic ligament is opened and the right crus and the inferior and anterior aspects of the esophagus are mobilized. Attention is then turned to the greater curvature of the stomach, opening the greater omentum, taking the short gastric vessels, and preserving the right gastroepiploic artery. Retrogastric attachments are taken down, and the left gastric vessels are divided with a stapler. A sixth laparoscopic port is placed in the right lower quadrant and the gastric conduit is created. No pyloric drainage procedure was performed. All patients received a jejunostomy either preoperatively or during the same procedure. The patient is then turned to the left lateral decubitus position for the chest portion of the procedure. Four thoracoscopy ports are used. Mobilization of the esophagus begins along the posterior aspect of the right hilum, and the azygos vein is divided. All paraesophageal lymph nodes and those in mediastinal station 7 are dissected entirely. The lateral aspect of the esophagus is dissected, and the gastric conduit is mobilized into the chest. Proper orientation of the gastric conduit is maintained. The esophagus is divided and the margins checked by frozen-section pathology. The anastomosis is preferably completed with a 28-mm end to end anastomosis (EEA) stapler (Covidien), and 2 purse-string sutures are used to secure the anvil of the stapler in the esophagus. The EEA stapler is introduced by enlarging the posterior, inferior incision and through a gastrotomy in the gastric fundus. The anastomosis is constructed, and the tip of the gastric fundus is removed using a linear stapler. The anastomosis suture line is not covered or reinforced. Two chest tubes are left in the pleural space at the end of the procedure: a 28F Argyle-type straight chest tube (Covidien) and a 19F Blake drain (Ethicon). Postoperative care Epidural analgesia is avoided in patients undergoing MIE. Postoperative pain control is achieved by a combination of intercostal nerve blocks during the operation, intravenous patient-controlled analgesia with opioids, and ketorolac. Routine extubation in the operating room is attempted in all patients. Patients routinely spend the first night in the ICU. Nasogastric tubes are left in place until there is return of bowel function (ie, passage
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of flatus or bowel movement) and remain in place until a postoperative barium swallow. Argyle-type chest tubes are typically removed on postoperative day 3 after tube feedings are started and there is no evidence of air or chyle leak. Blake drains (Ethicon) are typically removed after a routine barium swallow demonstrates no anastomotic leak, taking into account the same general criteria for chest tubes. Chest tubes are not left in place after resumption of a diet. Barium swallows are routinely ordered around the 5th or 6th postoperative day. If no anastomotic leak or delayed gastric emptying is demonstrated, the patient is started on a staged esophageal diet. Study end points The primary end points for this study were the rate of conversion to open procedure, surgical time, estimated blood loss, duration of chest drainage, time to initiation of oral intake, hospital length of stay, and postoperative morbidity and mortality. Total surgical time was defined as the time in minutes from skin incision to final skin closure. Abdominal surgical time was defined as the time from skin incision to reintubation with a doublelumen endotracheal tube. Chest surgical time was defined as the time from reintubation to final skin closure. Estimated blood loss was recorded after reconciling surgical and anesthesia records. Duration of chest drainage was recorded independently for each of the 2 chest tubes. Postoperative mortality was defined as deaths occurring during the same hospital stay or within the next 30 and 90 days after surgery. Anastomotic stricture was defined as the need for 2 or more postoperative dilations of the anastomosis. Statistical analysis The first 40 patients who underwent MIE represented the early-experience group (November 2007eDecember 2010) and the last 40 patients represented the lateexperience group (January 2011eOctober 2012). Data from the patients were analyzed using the statistical software Stata/SE 10.1 (StataCorp). Variables were analyzed as proportions, means, or medians with variability estimates in the form of SD and interquartile ranges (IQR), as appropriate. Fisher’s exact test was used to compare the distribution of categorical variables between groups. Continuous variables were analyzed using Student’s t-test or Wilcoxon rank sum test. Statistical significance was defined as a 2-sided p value 0.99 >0.99 0.62 0.48 0.77 >0.99 >0.99 0.49
87.1 18.2 75.7 21.8
96.5 15.9 79.6 20.7
7 (17.5) 4 (10.0)
8 (20.0) 3 (7.5)
>0.99 >0.99
40 (100) 38 (95) 37 (92.5)
40 (100) 38 (95) 21 (52.5)
>0.99 0.99 0.18
0.34 0.36 0.71 0.71 >0.99 >0.99 >0.99 0.43
*Excluding 1 patient with gastrointestinal stromal tumor. y Radiofrequency ablation. GIST, gastrointestinal stromal tumor; MIE, minimally invasive Ivor Lewis esophagectomy.
Postoperative care Results for postoperative care parameters are shown in Table 4. Intensive care unit length of stay was seen to increase significantly from a median of 1 day (IQR, 1e1 day) in the early-experience group to 1 day (IQR, 1e3 days) in the late-experience group (p ¼ 0.02). For the management of tubes and drains, there were no significant differences in the duration of nasogastric drainage between groups at a median of 5 days postoperatively. However, there were significant differences in the duration of chest drainage: Argyle-type (Covidien) and Blake (Ethicon) chest tubes were both pulled out at a median of 6 days in the early-experience groups, and they were removed at a median of 3 and 5 days, respectively, in the late-experience group of patients. A contrast swallow study was obtained routinely in all patients; however, it was obtained significantly sooner, by 1 day, in patients in the late-experience group (postoperative day 5), when compared with the early-experience group. There was no significant difference in the frequency of delayed gastric emptying between groups, as reported on this contrast study. Accordingly, oral intake with a staged esophageal diet was started significantly sooner in patients in the late-experience group, as seen in Table 4.
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Table 3.
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Intraoperative Variables and Pathologic Examination of Surgical Specimens
Variables
First 40 MIE
Last 40 MIE
Conversion to open, n (%) Jejunostomy placement at time of MIE, n (%) Pyloric drainage procedure, n (%) Size of EEA stapler for anastomosis, mm, n (%) 25 28 Total surgical time, min, median (IQR) Abdomen surgical time, min, median (IQR) Chest surgical time, min, median (IQR) Estimated blood loss, mL, median (IQR) Intraoperative transfusion, n (%) Extubated in operating room, n (%) Tumor location, n (%) Mid-esophagus Lower esophagus EGJ Pathologic staging, n (%)y Complete response 0 IA IB IIA IIB IIIA IIIB IIIC IV R0 resection, n (%) No. of harvested lymph nodes, median (IQR)y
2 (5.0) 37 (92.5) 0 (0)
0 (0) 33 (82.5) 0 (0)
p Value
0.49 0.31 *
>0.99 2 38 361.5 201 164 200 2 40
(5.0) (95.0) (302e429) (158e258) (127e204) (150e300) (5.0) (100)
1 (2.5) 29 (72.5) 10 (25.0) 5 1 13 3 3 6 6 2 0 0 40 19
(12.8) (2.6) (33.3) (7.7) (7.7) (15.4) (15.4) (5.1) (0) (0) (100) (12e34)
3 37 317 163.5 141 200 0 40
(7.5) (92.5) (255e368) (132e202) (114e184) (50e300) (0) (100)
1 (2.5) 17 (42.5) 22 (55.0) 7 0 8 4 0 13 4 3 1 0 40 21.5
(17.5) (0) (20.0) (10.0) (0) (32.5) (10.0) (7.5) (2.5) (0) (100) (11e30)
0.99
3
7.5
2
5.0
>0.99
*
*Unable to derive a p value for this comparison because all patients in both groups either presented or did not present this characteristic simultaneously.
which can negatively impact outcomes.18 Because of this, there has been increasing interest in adopting minimally invasive approaches to esophagectomy in an attempt to improve early postoperative outcomes. Minimally invasive esophagectomy has the potential for an easier postoperative recovery with fewer cardiopulmonary complications when compared with open approaches.19 In addition, enhanced visualization of abdominal and mediastinal structures by means of a minimally invasive, video-assisted approach might facilitate intraoperative steps, reduce injury to neighboring structures, improve lymph node harvest, and decrease blood loss.20 To support these notions, multiple small retrospective series have been published examining the outcomes of MIE.13 However, the largest series to date was published by Luketich and colleagues3 in 2012, and included 530 patients undergoing MIE. In this report, the rate of conversion to open procedure was 4%, median postoperative length of stay was 7 days, and median ICU length of stay was 2 days; vocal cord paresis occurred in 1% and anastomotic leak requiring intervention was observed in 4%. Mortality at 30 days was reported at an outstandingly low rate of 0.9%. These excellent results support the pursuit of MIE as the routine approach to esophagectomy. In addition, retrospective series have performed direct comparisons between MIE and open esophagectomy,19 showing a reduction in postoperative pulmonary complications in patients undergoing MIE, as well as shorter ICU and hospital lengths of stay. The benefits of a minimally invasive approach to esophagectomy were confirmed in a small randomized controlled trial published by Biere and colleagues20 in 2012, after comparing 59 patients randomly assigned to undergo a minimally invasive esophagectomy (which represented a 3-field McKeown-type esophagectomy in two thirds of
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Figure 2. Cumulative sum (CUSUM) plot for surgical time. Cumulative sum in minutes on the vertical axis is plotted against patient number on the horizontal axis. (A) Overall surgical time; (B) surgical time, abdominal stage; and (C) surgical time, thoracic stage.
patients, with the thoracoscopic portion being performed in the prone position) with 56 patients assigned to open esophagectomy. This trial showed a considerable reduction in postoperative pneumonia, hospital length of stay, postoperative pain scores, operative blood loss, and vocal cord paralysis, as well as improved quality of life at 6 weeks after surgery. Although larger prospective multi-institutional trials are awaited, it is not unreasonable to foresee MIE as the surgical approach of choice for the treatment of esophageal cancer in the near future. Despite its benefits, MIE is probably one of the most technically demanding operations in the field of general thoracic surgery and requires training in advanced laparoscopic and thoracoscopic surgical techniques. For MIE to continue to gain popularity and widespread applicability, formal surgical training in the technique to perform MIE
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should take place. Therefore, its learning curve needs to be defined to guide the training of residents, fellows, and thoracic surgeons who are looking to transition in their practice. As shown, patients in both groups were similar in terms of demographics, baseline comorbid conditions, esophageal pathology, and rates of neoadjuvant therapy, with some exceptions. More patients reported a smoking history in the late-experience group. This difference did not translate to a significantly higher proportion of patients having a diagnosis of COPD or worsened pulmonary function. Additionally, endoscopic ultrasound was not technically feasible in a higher proportion of patients in the late group due to a higher percentage of obstructing masses. This finding might have affected accurate clinical staging. However, most patients were classified as stages IIB or IIIA, and received neoadjuvant therapy. Finally, there was a shift in tumor location from a predominant lower esophageal location in the early experience to a predominant esophagogastric junction location in the late-experience group. We think this is a result of chance alone. There was not an intended selection bias toward operating more frequently on tumors located in the esophagogastric junction by means of MIE, as MIE is equally suitable for the surgical treatment of tumors in either location. These observed differences alone do not explain the results obtained in intraoperative and postoperative variables in the current study. When examining intraoperative variables, we observed similar rates of conversion to open procedure between the early- and late-experience groups, although the only 2 conversions were observed during the first 40 MIEs (patient numbers 15 and 29). Surgical time was seen to improve significantly in the late-experience group by a median of approximately 44 minutes. Shorter surgical times are a surrogate for proficiency with the technique and systematization of the operation, however, longer surgical times might also represent more challenging cases. Oncologic outcomes were comparable, as all patients underwent R0 resection and the number of lymph nodes harvested was similar and comparable with published series.3 The evaluation of the postoperative period revealed interesting findings. Intensive care unit length of stay increased substantially in the late-experience group. However, this finding did not translate into an overall prolonged hospital length of stay; in fact, total length of stay decreased by a median of 1 day in the last 40 patients and there were no differences in the disposition of patients at discharge. Taken together, this likely represents delays in the transfer of patients from the ICU to the floor, possibly due to bed availability issues.
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Figure 3. Cumulative sum (CUSUM) plot for postoperative care parameters. Cumulative sum in days on the vertical axis is plotted against patient number on the horizontal axis. (A) Duration of Argyle-type chest tube; (B) duration of Blake-type chest tube; (C) initiation of oral intake; and (D) length of hospital stay.
A very important aspect in the postoperative care of patients after esophagectomy is the management of drains and chest tubes, as well as the careful resumption of oral intake. We observed a very significant reduction in the duration of rigid Argyle chest tubes by a median of 3 days in the late-experience group, halving the duration seen in patients operated on during the early experience. This was also true for Blake chest tubes, which reduced their duration in the pleural space by a median of 1 day. A shorter duration of chest drainage can translate into reduced postoperative pain, improved patient comfort, and easier and earlier mobilization. A shorter duration of chest drainage can also represent a higher comfort level by the surgeon with the potential for thoracic duct leaks as well as anastomotic complications. Likely, this is the same reason we observed earlier ordering of routine contrast swallow studies in the lateexperience group and, as a consequence, earlier initiation of oral intake. Although this might not make a significant difference from a nutritional perspective because all patients were routinely started on enteral nutritional support through a jejunostomy on postoperative day 2, this can result in increased comfort to the patient as well as in encouragement during the recovery phase. To our knowledge, this is the first time that these postoperative care variables have been analyzed in detail in MIE patients. To have a better understanding of surgeon’s performance during our experience with MIE, we applied the CUSUM methodology to identify the moment along the entire experience when the outcomes of interest started
to improve significantly. As seen in Figures 2 and 3, surgical time, duration of chest drainage, re-initiation of oral intake, and hospital length of stay saw improved results after approximately 35 to 40 operations. This is an interesting finding that suggests that the number of patients needed to operate and take care of perioperatively to achieve improving results in these parameters is at least 35 to 40. Our findings are in concordance with previous recommendations provided by experts. In 2008, the Association of Upper Gastrointestinal Surgeons and the Association of Laparoscopic Surgeons of Great Britain and Ireland issued a consensus document with recommendations for the development and practice of MIE,21 stating that the learning curve for MIE is thought to be between 20 and 50 operations. Additionally, our findings are similar when compared with those derived from the evaluation of the learning curve of other minimally invasive techniques with esophagectomy, including hybrid approaches, which have reported improving outcomes after 14 to 46 operations.9,11-14 Therefore, a reasonable learning curve for a completely minimally invasive Ivor Lewis esophagectomy can require the operation and perioperative care of 35 to 40 patients. A possible explanation for the faster progression during the postoperative period observed in the late-experience group is that the surgeon became more comfortable with postoperative care as he gained experience with the operation, especially during this critical period of transition between advanced fellowship training and independent practice with a surgical technique that was being implemented at an academic center with extensive experience
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with esophageal surgical pathology. This is a fundamental part of the learning process. Some of these findings might be the reflection of a higher confidence level with technical aspects of the operation, such as minimal bleeding, the integrity of the intrathoracic anastomosis or the proper orientation and sizing of the gastric conduit. As these technical intraoperative steps improve and become more fluent and less flawed, they allow for faster progression during the postoperative period. Therefore, proper surgical technique is a sine qua non for being more aggressive with the removal of tubes and drains and the resumption of a diet during the postoperative period of MIE without resulting in increased morbidity. There are limitations to this study. First, it represents the learning curve of a single surgeon and as expected, it can change from surgeon to surgeon, depending on previous training and inherent skills. Additionally, we report our experience with 80 patients, and sample size might have contributed to statistical limitations. Also, as very well expressed by Sutton and colleagues,8 the learning curve described simply might not represent that of an individual surgeon, but that of an evolving specialist center in which the surgeon coordinates care. Changes in performance due to improvements in anesthesia, ancillary operating room staff, critical care, nursing, and others involved in the care of MIE patients are inseparable from those thought to be secondary to surgical performance. Therefore, our results might not be extrapolated in a different setting. The current study should prompt other centers and surgeons to evaluate their learning curve during implementation of MIE.
CONCLUSIONS We have described the learning curve for MIE for a single surgeon at a tertiary care center. For the first time in the MIE literature, we analyzed in detail the management of drains and tubes during the postoperative care. Additionally, we applied the CUSUM methodology to try to identify more precisely the moment along our experience when we observed improved results. Our findings suggest that the operation and perioperative care of 35 to 40 patients results in improving results in intraoperative and postoperative care parameters in subsequent patients. We expect that these results serve as support for development of curricula and specific requirements in thoracic surgery trainees. Author Contributions Study conception and design: Tapias, Morse Acquisition of data: Tapias, Morse Analysis and interpretation of data: Tapias, Morse
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Drafting of manuscript: Tapias, Morse Critical revision: Tapias, Morse REFERENCES 1. Birkmeyer JD, Siewers AE, Finlayson EV, et al. Hospital volume and surgical mortality in the United States. N Engl J Med 2002;346:1128e1137. 2. Wright CD, Kucharczuk JC, O’Brien SM, et al. Predictors of major morbidity and mortality after esophagectomy for esophageal cancer: a Society of Thoracic Surgeons General Thoracic Surgery Database risk adjustment model. J Thorac Cardiovasc Surg 2009;137:587e595. 3. Luketich JD, Pennathur A, Awais O, et al. Outcomes after minimally invasive esophagectomy: review of over 1000 patients. Ann Surg 2012;256:95e103. 4. Wohl H. The cusum plot: its utility in the analysis of clinical data. N Engl J Med 1977;296:1044e1045. 5. Bokhari MB, Patel CB, Ramos-Valadez DI, et al. Learning curve for robotic-assisted laparoscopic colorectal surgery. Surg Endosc 2011;25:855e860. 6. Buchs NC, Pugin F, Bucher P, et al. Learning curve for robotassisted Roux-en-Y gastric bypass. Surg Endosc 2012;26: 1116e1121. 7. Okrainec A, Ferri LE, Feldman LS, Fried GM. Defining the learning curve in laparoscopic paraesophageal hernia repair: a CUSUM analysis. Surg Endosc 2011;25:1083e1087. 8. Sutton DN, Wayman J, Griffin SM. Learning curve for oesophageal cancer surgery. Br J Surg 1998;85:1399e1402. 9. Osugi H, Takemura M, Higashino M, et al. Learning curve of video-assisted thoracoscopic esophagectomy and extensive lymphadenectomy for squamous cell cancer of the thoracic esophagus and results. Surg Endosc 2003;17: 515e519. 10. Ninomiya I, Osugi H, Tomizawa N, et al. Learning of thoracoscopic radical esophagectomy: how can the learning curve be made short and flat? Dis Esophagus 2010;23: 618e626. 11. Guo W, Zou YB, Ma Z, et al. One surgeon’s learning curve for video assisted thoracoscopic esophagectomy for esophageal cancer with the patient in lateral position: how many cases are needed to reach competence? Surg Endosc 2013;27: 1346e1352. 12. Song SY, Na KJ, Oh SG, Ahn BH. Learning curves of minimally invasive esophageal cancer surgery. Eur J Cardiothorac Surg 2009;35:689e693. 13. Lin J, Kang M, Chen C, et al. Thoracolaparoscopy oesophagectomy and extensive two-field lymphadenectomy for oesophageal cancer: introduction and teaching of a new technique in a high-volume centre. Eur J Cardiothorac Surg 2013;43:115e121. 14. Kunisaki C, Kosaka T, Ono HA, et al. Significance of thoracoscopy-assisted surgery with a minithoracotomy and hand-assisted laparoscopic surgery for esophageal cancer: the experience of a single surgeon. J Gastrointest Surg 2011;15: 1939e1951. 15. Tapias LF, Morse CR. Minimally invasive Ivor Lewis esophagectomy after induction therapy yields similar early outcomes to surgery alone. Innovations (Phila) 2011;6:331e336. 16. Pennathur A, Awais O, Luketich JD. Technique of minimally invasive Ivor Lewis esophagectomy. Ann Thorac Surg 2010; 89:S2159eS2162.
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17. Tapias LF, Morse CR. A preliminary experience with minimally invasive Ivor Lewis esophagectomy. Dis Esophagus 2012;25:449e455. 18. Tapias LF, Muniappan A, Wright CD, et al. Short and longterm outcomes after esophagectomy for cancer in elderly patients. Ann Thorac Surg 2013;95:1741e1748. 19. Sihag S, Wright CD, Wain JC, et al. Comparison of perioperative outcomes following open versus minimally invasive Ivor Lewis oesophagectomy at a single, high-volume centre. Eur J Cardiothorac Surg 2012;42:430e437.
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20. Biere SS, van Berge Henegouwen MI, Maas KW, et al. Minimally invasive versus open oesophagectomy for patients with oesophageal cancer: a multicentre, open-label, randomised controlled trial. Lancet 2012;379:1887e1892. 21. Association of Upper Gastrointestinal Surgeons, Association of Laparoscopic Surgeons. A Consensus View and Recommendations on the Development and Practice of Minimally Invasive Oesophagectomy. London: AUGIS; 2008. Available at: http://www.augis.org/pdf/MIO_Consensus.pdf. Accessed February 6, 2014.
