In April 2019, Drs Michel Gagner (Hopital du Sacré Coeur, Montréal, the Westmount Square Surgical Center, Westmount, QC, Canada and the Herbert Wertheim School of Medicine, Florida International University, Miami, USA) and Paul Kemmeter (Mercy Health Saint Mary’s, Grand Rapids, MI, USA) published a systematic review comparing staple-line leak rates in five reinforcement options following laparoscopic sleeve gastrectomy (LSG) in the journal Surgical Endoscopy1. Bariatric News spoke with the authors to discuss the outcomes and implications of the paper.
“This paper is an update on a previous systematic review2 published in 2014 and includes data from 2012-2016, with 1,633 eligible new papers. We also had more papers on tissue sealants and decided to add this 5th strategy in the systematic review,” explained Dr Gagner.
The previous paper included data from 88 papers and 8,920 patients and reported that there were 191 leaks, an overall leak rate 2.1%. Leak rates ranged from 1.09% for absorbable polymer membrane (APM, also known as GORE® SEAMGUARD® Bioabsorbable Reinforcement) to 3.3% for nonabsorbable bovine pericardial strips (BPS) and the APM leak rate was significantly lower than other groups (p< 0.05). The paper concluded that using APM staple-line reinforcement in LSG was significantly lower than oversewing, BPS reinforcement or no reinforcement.
In addition to tissue sealants, the five reinforcement options include in this updated study were no reinforcement (no-SLR), oversewing (suture), BPS, tissue sealant or fibrin glue (seal) or APM.
“We believe that using a thin buttressing material improves staple compression compared with using Bovine Pericardium (BPS) that has variable thicker reinforcement that can result in disparities of tissue compression, and potentially resulting in an inadequate segment of staple line."
“In this current study, the COVIDIEN DUET Tissue Reinforcement Stapler System was eliminated from the data set since it was previously removed from the market and we included surgical sealants in the analysis,” added Dr Kemmeter.
The final analysis included 40,653 patients from 148 papers and reported a total of 607 leaks, an overall leak rate of 1.5%. With over 40,650 procedures included in the analysis, the authors reported that the percentage of leaks was statistically significantly lower with APM (0.7%), then suture (1.21%, p=0.007), sealants (1.89%, p=0.001) and no-SLR (1.89%, p=0.027) and finally, BPS (2.73%, p<0.0001).
“Interestingly, although the patients in the APM group were statistically older, a variable shown to be a risk factor for increased leaks, the overall leak rate was statistically lowest in the APM group compared to all other techniques,” Dr Kemmeter noted. When looking at only studies conducted in the US, the APM reinforcement method continued to have the lowest leak rate (0.39%) among the methods evaluated.
“One of the big differences between the US and other regions is that the US adopted the Roux-en-Y gastric bypass (RYGB) as its ‘gold standard’ operation in the late 1990’s to early 2000’s versus other regions that were doing significantly more gastric banding. It would make sense that the technical challenges of the RYGB had provided surgeons in the US with a shortened learning curve once the LSG was adopted more widely.”
Differences in leak rates
To account for the significant difference in leak rates between APM (0.7%) and BPS (2.73%), the authors hypothesise this is associated with using a thin buttressing material (0.4mm average total thickness with a maximum total thickness of 0.5mm) vs the variable thicker BPS reinforcement (0.4- 1.2mm).
“We believe that using a thin buttressing material improves staple compression compared with using Bovine Pericardium (BPS) that has variable thicker reinforcement that can result in disparities of tissue compression, and potentially resulting in an inadequate segment of staple line,” Dr Gagner added. “Another important factor was the BPS group had a statistically shorter distance from the pylorus - but no difference in bougie size - and perhaps this was creating a pressure gradient difference or thicker tissue stapled in the distal stomach?”
Dr Kemmeter cautioned that the study was designed to identify differences in leak rates and therefore any discussion on possible cause(s) of variation in leak rates is speculative. Nevertheless, he noted that when buttressing on both the anvil and cartridge sides, the buttressing material doubles (0.4mm for APM vs. 0.4-1.2mm for BPS), so it is therefore feasible that the six-fold variation in thickness of the BPS could contribute to either too tight (crushing resulting in tearing or ischemia) or too loose staple lines, both of which could contribute to staple line leaks.
“Certain areas are ‘hazard zones’ when completing a vertical sleeve gastrectomy, including the angularis incisura (too narrow can result in a stricture) and the oesophagus, which is weaker than gastric tissue. Work completed by the Michigan Bariatric Surgery Collaborative has demonstrated that surgeons who handle tissue more carefully have lower complication rates.”
Dr Gagner also highlighted the importance of cartridge selection and speculated, based on his medical experience, that as black cartridges are the highest staple height closing at 2.3mm, they may be inappropriate for BPS in combination with thick gastric tissue. For example, thick stomach tissue can be up to 5.5mm in men and adding 1.2mm of BPS results in 6.7mm and that is just too much combined tissue/SLR area to compress to 2.3mm.
They also speculate that the temporal reduction in leak complications in LSG is most likely related to surgeon experience and that selected operative strategies may result in lower leak rates after sleeve gastrectomy (i.e. improved dissection with preservation of healthier and more vascular tissue by reducing thermal injury and tissue trauma, selection of appropriate staple height to accommodate tissue thickness, avoidance of narrowing near the angularis incisura, choice of adequate bougie sizes, and avoidance of stapling along the oesophagus).
“I think there is a learning curve about the proper staple height according to certain tissue thickness, avoidance of thermal injury, more testing, avoidance of strictures at the incisura and twists, and selecting a larger bougie size, 32Fr or less is, in my opinion, unsuitable,” Dr Gagner noted.
“Since buttressing material has for the most part remained constant, the variable that has changed over the course of these studies is surgeon experience. We know from previous literature that certain variables increase the risk of a leak (e.g. bougie size, higher BMI, and surgeon experience),” added Dr Kemmeter. “Certain areas are ‘hazard zones’ when completing a vertical sleeve gastrectomy, including the angularis incisura (too narrow can result in a stricture) and the oesophagus, which is weaker than gastric tissue. Work completed by the Michigan Bariatric Surgery Collaborative has demonstrated that surgeons who handle tissue more carefully have lower complication rates3. Based on our analysis, this in one of the largest and most comprehensive systematic reviews published to date.”
The authors acknowledged that there are limitations to the study and that additional research or improvements in data collection (ie staple height selection is not uniformly collected) could result in further insights. For example, as this was a review study there are inherent limitations based on the quality of the data provided within each study and the vast majority of the studies included were non-randomised. They both agreed that the lack of more granular data such as stapler type, staple height, location of reinforcement use, location of leak, etc., prevented them from being able to make more conclusions from their study, adding that future research should incorporate these elements as well as tissue thickness data, compression times, manual vs powered stapler etc., and examining the cost-effectiveness of reducing leaks could be important.
It is noteworthy that the data from this current study is supported by the study published in 20142, in that APM had the lowest leak rate (0.73% vs 1.09%), followed by suture (1.21% vs 2.04%), NO-SLR (1.89% vs 2.60%), and BPS (2.73% vs 3.30%). This reliability would lend support that the selection of staple-line reinforcement technique is important in contributing to leak rates,” Dr Kemmeter noted.
These sentiments were echoed by Dr Gagner who added that the lack of more granular data has led to conflicting reports in the literature. For example, the much publicised and scrutinised paper by Hutter et al4 concluded that SLR was associated with increased leak rates (0.96% vs 0.65%) and lower bleed rates (0.75% vs 1.00%), compared to no SLR at patient level. However, a more recent paper by Demeusy et al5 found SLR decreased the rate of bleeding and re-operations, but had no effect on the post-operative leak rate.
It should be noted that neither the Hutter nor Demeusy study looked at the data specifically for each different type of SLR, but instead made statements about SLR as a whole. However, in this study by Gagner and team, the data clearly demonstrates that the type of SLR used makes a significant impact on the leak rates reported.
“As we saw in the paper by Hutter et al, it is paramount that authors caution readers about the use of incomplete or non-granular data in papers, especially if they are making conclusions based on this data,” concluded Dr Gagner. “Making such conclusions, without sufficient evidence, can have a serious impact on patient care and health policy.”
- Gagner M, Kemmeter P. Comparison of laparoscopic sleeve gastrectomy leak rates in five staple‑line reinforcement options: a systematic review. Surgical Endoscopy. April 2019
- Gagner M, Buchwald JN. Comparison of laparoscopic sleeve gastrectomy leak rates in four staple-line reinforcement options: a systematic review. Surg Obes Relat Dis 10(4):713–723
- Birkmeyer JD, Finks JF, O’Reilly A, Oerline M, Carlin AM, Nunn AR, Dimick J, Banerjee M, Birkmeyer NJ; Michigan Bariatric Surgery Collaborative. Surgical skill and complication rates after bariatric surgery. N Engl J Med. 2013 Oct 10;369 (15):1434-42
- Hutter et al; The Impact of Different Surgical Techniques on Outcomes in Laparoscopic Sleeve Gastrectomies: The First Report from the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP). Ann Surg. 2016 Sep;264(3):464-73)
- Demeusy et al; Current role of staple line reinforcement in 30-day outcomes of primary laparoscopic sleeve gastrectomy: an analysis of MBSAQIP data, 2015–2016. Surgery for Obesity and Related Diseases, Volume 14, Issue 10, 1454 – 1461)
Disclosure - Drs Gagner and Kemmeter have previously received research and/or consultancy grants/fees from W. L. Gore & Associates. Refer to Instructions for Use at goremedical. com for a complete description of all warnings, precautions and contraindications.
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GORE, SEAMGUARD and designs are trademarks of W. L. Gore & Associates. ©2019 W. L. Gore & Associates, Inc. AY1512-EN1 November 2019