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Comment on: Comparison of endostapler performance in challenging tissue applications
Comparison of Endostapler Performance / Surgery for Obesity and Related Diseases 9 (2013) 417–422
Conclusion This study found that in more challenging and variable tissue applications, the EGIA60AXT reload had superior performance compared with the ECR60G reload with respect to B-shaped staple formation and the incidence of malformed staples. These stapler performance metrics indicate a stapler’s ability to perform reliably and consistently, especially when used in challenging and variable tissue; they may be associated with reducing anastomotic complications, such as dehiscence or postoperative leaks, as noted in many peer-reviewed publications. Disclosures The authors are employees of Covidien Surgical Solutions which solely funded this work. Note added in proof: Following ‘‘in press’’ publication, the Disclosure information was corrected as shown above. References
421
[3] Manufacturer’s instruction for use by Covidien, North Haven, CT, USA. [4] Manufacturer’s instruction for use by Ethicon Endo-Surgery Inc., Cincinnati, OH, USA. [5] Nakayama S, Hasegawa S, Nagayama S, et al. The importance of precompression time for secure stapling with a linear stapler. Surg Endosc 2011;25:2382–6. [6] Baker RS, Foote J, Kemmeter P, Brady R, Vroegop T, Serveld M. The science of stapling and leaks. Obes Surg 2004;14:1290–8. [7] Elariny H, Gonzalez H, Wang B. Tissue thickness of human stomach measured on excised gastric specimens from obese patients. Surg Tech Int 2005;14:119–24. [8] Almahmeed T, Gonzalez R, Nelson LG, Haines K, Gallagher SF, Murr MM. Morbidity of anastomotic leaks in patients undergoing Roux-en-Y gastric bypass. Arch Surg 2007;142:954–7. [9] Buchs NC, Gervaz P, Secic M, Bucher P, Mugnier-Konrad B, Morel P. Incidence, consequences, and risk factors for anastomotic dehiscence after colorectal surgery: a prospective monocentric study. Int J Colorect Dis 2008;23:265–70. [10] Lee S, Carmody B, Wolfe L, et al. Effect of location and speed of diagnosis on anastomotic leak outcomes in 3828 gastric bypass cases. J Gastrointest Surg 2007;11:708–13. [11] Platell C, Barwood N, Dorfmann G, Makin G. The incidence of anastomotic leaks in patients undergoing colorectal surgery. Colorect Dis 2006;9:71–9. [12] Bellanger DE, Greenway FL. Laparoscopic sleeve gastrectomy, 529 cases without a leak: short-term results and technical considerations. Obes Surg 2011;21:146–50.
[1] Ravitch MM, Brown IW, Daviglus GF. Experimental and clinical use of the Soviet bronchus stapling instruments. Surgery 1959;46:97–108. [2] Androsov PPI. New instruments for thoracic surgery. Dis Chest 1963;44:590–7.
Editorial comment
Comment on: Comparison of endostapler performance in challenging tissue applications Despite the significant advances in stapling made over the decades, much remains to be understood about the interaction of surgical staples and tissue. We know that a multitude of factors affect stapler performance: some within the control of the manufacturer, some within control of the clinician, and some controlled by neither. We also know that only careful science and well-designed studies will yield the desired new insights. Although appearing to reveal differences in 2 manufacturers’ stapler performance, the article by Contini et al. instead demonstrates the importance of solid experimental design to study conclusions. The study design fails to control important variables and makes potentially faulty assumptions, resulting in conclusions that may not be valid. A basic tenet of good study design is to minimize or remove all potentially confounding variables except for the one of interest. Only then can results be attributed to a specific factor.
As soon as a second variable is introduced, experimental design becomes more complicated. In the case of the Contini et al. study, staple leg length—a factor presumably key to staple formation—is not controlled; that is, the staple cartridges from the 2 manufacturers had 2 different leg lengths. Staple formation with Covidien Tri-Staple EGIA60 AXT reloads (4to 5-mm staple leg lengths) was compared with that with Ethicon ECR60 G reloads (4.1-mm staple leg lengths). It is clear to the observant reader that, given equivalent tissue thickness, staple formation would not necessarily be the same. Adequate staple form can occur only if the penetrating legs of the staple (1) are able to pass through the material to be held and (2) still have sufficient length to fold in the pockets of the stapler’s anvil to make the desired B-form. Solid experimental design would dictate measurement of staple formation on equivalent tissue thicknesses. Although staple line locations and orientations were provided, there is
422
E. Contini et al. / Surgery for Obesity and Related Diseases 9 (2013) 417–422
no indication that the 2 companies’ cartridges were fired on the same tissue thickness, or even on the same stomachs. Given the fact that the comparison was one between apples and oranges on several counts, the article’s conclusions can understandably be held in question. Second, the authors assume a causal relationship between staple formation and stapler performance (i.e., leak-free anastomosis). This may seem reasonable at the outset; however, good staple formation does not necessarily ensure good clinical performance. What is clear is that a number of factors outside of staple formation play a role in successful anastomosis (e.g., tissue ischemia, tissue trauma, and coaptation of mucosal surfaces). Furthermore, and with this the authors agree, any real comparison would, at the very least, require leak pressure tests immediately postfiring to determine anastomotic integrity. In an ideal world, these tests would be conducted as survival studies because the true goal of the staplers is to
provide a leak-free anastomosis, which can be determined only in a living subject. Finally, exploration of tissue healing and trauma should certainly be considered in any real comparison of stapler performance. Solid study design is inherent in making defendable, valuable deductions. Although Contini et al. supported the study with strong statistics, unfortunately, the uncontrolled variables and untenable assumptions make the paper’s conclusions questionable. Comparative studies have always been, and will remain, a necessary part of improving patient outcomes. It is incumbent upon clinicians and manufacturers alike to use rigorous scientific approaches to identify and refine the best tools and the best techniques possible. Elliott J. Fegelman, M.D., F.A.C.S. Ethicon EndoSurgery, Cincinnati, Ohio
Conclusion This study found that in more challenging and variable tissue applications, the EGIA60AXT reload had superior performance compared with the ECR60G reload with respect to B-shaped staple formation and the incidence of malformed staples. These stapler performance metrics indicate a stapler’s ability to perform reliably and consistently, especially when used in challenging and variable tissue; they may be associated with reducing anastomotic complications, such as dehiscence or postoperative leaks, as noted in many peer-reviewed publications. Disclosures The authors are employees of Covidien Surgical Solutions which solely funded this work. Note added in proof: Following ‘‘in press’’ publication, the Disclosure information was corrected as shown above. References
421
[3] Manufacturer’s instruction for use by Covidien, North Haven, CT, USA. [4] Manufacturer’s instruction for use by Ethicon Endo-Surgery Inc., Cincinnati, OH, USA. [5] Nakayama S, Hasegawa S, Nagayama S, et al. The importance of precompression time for secure stapling with a linear stapler. Surg Endosc 2011;25:2382–6. [6] Baker RS, Foote J, Kemmeter P, Brady R, Vroegop T, Serveld M. The science of stapling and leaks. Obes Surg 2004;14:1290–8. [7] Elariny H, Gonzalez H, Wang B. Tissue thickness of human stomach measured on excised gastric specimens from obese patients. Surg Tech Int 2005;14:119–24. [8] Almahmeed T, Gonzalez R, Nelson LG, Haines K, Gallagher SF, Murr MM. Morbidity of anastomotic leaks in patients undergoing Roux-en-Y gastric bypass. Arch Surg 2007;142:954–7. [9] Buchs NC, Gervaz P, Secic M, Bucher P, Mugnier-Konrad B, Morel P. Incidence, consequences, and risk factors for anastomotic dehiscence after colorectal surgery: a prospective monocentric study. Int J Colorect Dis 2008;23:265–70. [10] Lee S, Carmody B, Wolfe L, et al. Effect of location and speed of diagnosis on anastomotic leak outcomes in 3828 gastric bypass cases. J Gastrointest Surg 2007;11:708–13. [11] Platell C, Barwood N, Dorfmann G, Makin G. The incidence of anastomotic leaks in patients undergoing colorectal surgery. Colorect Dis 2006;9:71–9. [12] Bellanger DE, Greenway FL. Laparoscopic sleeve gastrectomy, 529 cases without a leak: short-term results and technical considerations. Obes Surg 2011;21:146–50.
[1] Ravitch MM, Brown IW, Daviglus GF. Experimental and clinical use of the Soviet bronchus stapling instruments. Surgery 1959;46:97–108. [2] Androsov PPI. New instruments for thoracic surgery. Dis Chest 1963;44:590–7.
Editorial comment
Comment on: Comparison of endostapler performance in challenging tissue applications Despite the significant advances in stapling made over the decades, much remains to be understood about the interaction of surgical staples and tissue. We know that a multitude of factors affect stapler performance: some within the control of the manufacturer, some within control of the clinician, and some controlled by neither. We also know that only careful science and well-designed studies will yield the desired new insights. Although appearing to reveal differences in 2 manufacturers’ stapler performance, the article by Contini et al. instead demonstrates the importance of solid experimental design to study conclusions. The study design fails to control important variables and makes potentially faulty assumptions, resulting in conclusions that may not be valid. A basic tenet of good study design is to minimize or remove all potentially confounding variables except for the one of interest. Only then can results be attributed to a specific factor.
As soon as a second variable is introduced, experimental design becomes more complicated. In the case of the Contini et al. study, staple leg length—a factor presumably key to staple formation—is not controlled; that is, the staple cartridges from the 2 manufacturers had 2 different leg lengths. Staple formation with Covidien Tri-Staple EGIA60 AXT reloads (4to 5-mm staple leg lengths) was compared with that with Ethicon ECR60 G reloads (4.1-mm staple leg lengths). It is clear to the observant reader that, given equivalent tissue thickness, staple formation would not necessarily be the same. Adequate staple form can occur only if the penetrating legs of the staple (1) are able to pass through the material to be held and (2) still have sufficient length to fold in the pockets of the stapler’s anvil to make the desired B-form. Solid experimental design would dictate measurement of staple formation on equivalent tissue thicknesses. Although staple line locations and orientations were provided, there is
422
E. Contini et al. / Surgery for Obesity and Related Diseases 9 (2013) 417–422
no indication that the 2 companies’ cartridges were fired on the same tissue thickness, or even on the same stomachs. Given the fact that the comparison was one between apples and oranges on several counts, the article’s conclusions can understandably be held in question. Second, the authors assume a causal relationship between staple formation and stapler performance (i.e., leak-free anastomosis). This may seem reasonable at the outset; however, good staple formation does not necessarily ensure good clinical performance. What is clear is that a number of factors outside of staple formation play a role in successful anastomosis (e.g., tissue ischemia, tissue trauma, and coaptation of mucosal surfaces). Furthermore, and with this the authors agree, any real comparison would, at the very least, require leak pressure tests immediately postfiring to determine anastomotic integrity. In an ideal world, these tests would be conducted as survival studies because the true goal of the staplers is to
provide a leak-free anastomosis, which can be determined only in a living subject. Finally, exploration of tissue healing and trauma should certainly be considered in any real comparison of stapler performance. Solid study design is inherent in making defendable, valuable deductions. Although Contini et al. supported the study with strong statistics, unfortunately, the uncontrolled variables and untenable assumptions make the paper’s conclusions questionable. Comparative studies have always been, and will remain, a necessary part of improving patient outcomes. It is incumbent upon clinicians and manufacturers alike to use rigorous scientific approaches to identify and refine the best tools and the best techniques possible. Elliott J. Fegelman, M.D., F.A.C.S. Ethicon EndoSurgery, Cincinnati, Ohio