The Effects of Reinforcement Methods on Burst Pressure in Resected Sleeve Gastrectomy Specimens

Abstract

Background:

Staple-line leak is a life-threatening complication of laparoscopic sleeve gastrectomy. Reinforcement materials have been reported to lower the risk of staple-line bleeding, but their effects on leak risk have not been elucidated. The aim of this study was to compare the effects of two supportive techniques on burst pressures in sleeved gastrectomy specimens.

Materials and Methods:

Thirty patients who underwent laparoscopic sleeve gastrectomy were evaluated. The resected sleeve gastrectomy specimens were categorized into three groups. Group 1 had no extra support in the staple line, Group 2 had oversewing with continuous suture on the staple line, and Group 3 had fibrin sealant (Tisseel^®; Baxter, Deerfield, IL) on the staple line. The end point was the first detectable leakage, at which point leak pressure and the anatomic site of leakage were recorded.

Results:

Thirty sleeved gastrectomy specimens were included (each group included 10 specimens). There were no differences among group in terms of age, sex, and body mass index. The leak pressure was significantly higher (106±10.5 mm Hg) in Group 2 (P<.01). Leaks occurred significantly more frequently in the staple line than in the staple junction points (P=.014).

Conclusions:

Oversewing the staple line with 3-0 Vicryl^® (Ethicon, Somerville, NJ) suture significantly increased the strength of the staple line. Increases in intraluminal pressure are known to be one of the significant risks in leak etiology. Thus, we concluded that oversewing the staple line with 3-0 Vicryl suture can be beneficial in the prevention of leaks. However, further work is necessary in this area of research.

Introduction

The use of laparoscopic sleeve gastrectomy has been rapidly growing since it was first introduced in the year 2000. Individuals who undergo this procedure are able to lose weight effectively and have fewer obesity-related comorbidities than those undergoing similar procedures.¹ The most important advantages of this technique include preservation of gastrointestinal tract anatomy, protection from malabsorption, and capability of being switched to other operations. Serious side effects of the procedure can include serious bleeding and leaks, whereas less severe complications include gastroesophageal reflux disease, stricture formation, gastric tube dilation, and inadequate weight loss.¹

A staple-line leak is a life-threatening complication of laparoscopic sleeve gastrectomy. The rate of this complication has been reported to vary between 1.6% and 19%.^2,3 Gastric wall strength is critical in the early postoperative period after laparoscopic sleeve gastrectomy.⁴ The staple instrument, the quality of the stomach tissue, and the surgical technique are significant factors that can affect gastric wall strength.⁵ There are many complications related to staple use, and these include technical failure, bleeding, leaks, and fistulas.^6–11 Many surgeons use staple-line reinforcement materials in order to reduce the number of complications. Reinforcement materials have been reported to lower the risk of staple-line bleeding, but their effects on leak risk have not been elucidated.¹² There are several staple-line reinforcement techniques, including oversewing the staple line with suture, covering the staple line with jejunum or omentum, and supporting the staple line with bioabsorbable materials, including glycolide trimethylene carbonate copolymer,^13,14 bovine pericardium strips,^15,16 porcine small intestinal submucosa,^17,18 and Floseal^® (Baxter, Deerfield, IL).¹⁹ Although adding extra support to the staple line is highly recommended, there has not yet been a consensus as to which of the aforementioned techniques is the most effective in providing this extra support.¹⁹

Some surgeons evaluate the presence of a staple-line leak with an intraoperative leak test. For this test, the upper abdomen is filled with normal saline, and air pressure is applied with the gastric sleeve tube that has been formed. Potential leaks are detected by the formation of air bubbles on the staple line. Theoretically, this test may impair the staple line. As shown in the literature, burst pressure is used in many procedures, especially for measuring the strength of the anastomosis line.²⁰ In laparoscopic sleeve gastrectomy, oversewing with suture and fibrin sealant (Tisseel^®; Baxter) are often used to prevent leaks and bleeding. However, no studies have reported the effects of oversewing with continuous suture or fibrin sealant (Tisseel) on burst pressure in fresh tissue in humans. In this study, we compared the effects of two reinforcement techniques in terms of staple-line strength and on burst pressures of the sleeved stomach following the laparoscopic sleeve gastrectomy.

Materials and Methods

After their signed consent forms were received, 30 patients who underwent laparoscopic sleeve gastrectomy in our clinic between January 2013 and May 2013 were included in this study. Approval from the institutional review board was obtained prior to starting the trial. After the standard laparoscopic sleeve gastrectomy surgical procedure, excised specimens were extracted from the abdominal cavity, and these specimens were categorized into three groups. Group 1 had no extra support on the staple line of resected gastrectomy specimens, Group 2 had oversewing with continuous suture on the staple line of resected gastrectomy specimens, and Group 3 had fibrin sealant (Tisseel) on the staple line of resected gastrectomy specimens.

Surgical procedure

All patients were operated on by three surgeons experienced in obesity surgery. The patient lies in a supine position on the operating table with his or her arms extended in abduction and legs opened, in the reverse Trendelenburg position. Abdominal insufflation is set at 15 mm Hg. Trocars are placed as follows: a 10-mm trocar, 20 cm below the xiphoid process for the 30° optical system; a 5-mm trocar on the left anterior axillary line; a 5-mm trocar on the left midclavicular line just between the first and the second trocars; a 15-mm trocar on the right midclavicular line; and a 5-mm trocar below the xiphoid process. Using a 5-mm dissecting coagulator, the greater curvature of the stomach is mobilized at a point 3 cm proximal to the pylorus. The lesser sac is entered, and staying close to the wall of the stomach, the greater curvature ligaments (gastrosplenic and gastrocolic) are divided all the way up to the angle of His. Retrogastric adhesions are taken down with an advanced bipolar device (LigaSure™; Covidien, Mansfield, MA) to allow for complete mobilization of the stomach. After a complete mobilization of the stomach has been reached, a 40-French orogastric tube is inserted transorally into the pylorus and placed against the lesser curvature. Gastric transection by an Echelon Flex™ (Ethicon Endo-Surgery, Blue Ash, OH) stapler begins at a point 3 cm proximal to the pylorus, leaving the antrum and preserving gastric emptying. We use the green cartridge for the first firing and blue cartridges for the remaining ones in all cases. The resected sleeve gastrectomy specimen was removed through a 15-mm trocar site from the abdomen. After the surgical procedure was finished, the sleeved gastrectomy specimens are carefully retrieved by enlarging the 15-mm trocar incisions, with special care to avoid tearing the gastric wall or disrupting the staple line during the extraction.

Burst pressure measurement

After extraction of gastrectomy specimens from the abdominal cavity, all specimens were inspected for staple line and overall integrity, and only intact specimens were included in the study. Specimens in Group 1 did not receive any extra support on the staple line of the resected gastrectomy material. Two 10-French infusion catheters were inserted through the proximal (fundus) and distal (antrum) sections without disruption the staple line. One catheter was used for injection of normal saline colored with methylene blue into the lumen. Continuous pressure was assessed on the other catheter. After calibration of the arterial pressure system, saline with methylene blue added was injected constantly into the lumen with a syringe pump at a flow rate of 50 mL/minute, and pressure was monitored. The end point was the first detectable leakage, at which point leak pressure was recorded. The anatomic site of leakage was also noted to include whether the leak occurred through the staple-line seam or at some other site on the gastric specimen (Fig. 1).

FIG. 1.

View of the burst pressure measuring device with a resected gastric specimen. Arrows indicate the leak localization.

In Group 2, the staple line of the resected gastrectomy specimens was extracorporeally reinforced by oversewing continuously with a 3-0 atraumatic Vicryl^® (Ethicon, Somerville, NJ) suture. In Group 3, the staple line of the resected gastrectomy specimens was extracorporeally covered with fibrin sealant (Tisseel). Burst pressure was assessed using the same technique in Groups 2 and 3 as those in Group 1.

Statistical analysis

Analysis of variance with post hoc testing (Games–Howell) was used to compare numerical variables between groups. To compare the nominal data, chi-squared tests and the Kolmogorov–Smirnov test were used. Kruskal–Wallis analysis of variance was used to assess the difference among the three groups for the ordinal variables. All the above tests were performed using Statistical Package for Social Sciences version 19.0 software (SPSS Inc., Chicago, IL). All tests were two-sided, and P<.05 was considered to be significant.

Results

During this study period 37 sleeve gastrectomies were performed. However, seven specimens were excluded because of lacerations on the gastric wall or disruption of the staple line. Consequently, only 30 resected gastric specimens were included in this study. Each group consisted of 10 specimens. Ten patients were male, and 20 were female. The demographic features of the groups are shown in Table 1.

Table 1.

Patients' Characteristics

	Group 1 (n=10) (control)	Group 2 (n=10) (oversew suture)	Group 3 (n=10) (Tisseel)	P
Age (years)
Mean±SD	42.4±12.02	43.3±10.4	39.1±10.9	>.05
Range	21–63	27–67	22–52	>.05
Gender (n)
Male	4	4	2	>.05
Female	6	6	8	>.05
BMI (kg/m²)
Mean±SD	44.6±2.3	47.2±7.7	46.9±6.4	>.05
Range	41–48	37–63	39–47.5	>.05

BMI, body mass index; SD, standard deviation.

The average (mean±standard deviation) burst pressure was 30.5±3.06 mm Hg in Group 1 (no support material), 106±10.5 mm Hg in Group 2 (oversewing), and 28±5.09 mm Hg in Group 3 (fibrin sealant [Tisseel]). The burst pressure was significantly higher in Group 2 than in the other two groups (P<.01). However, there were no significant differences between the fibrin sealant (Tisseel)–supported group (Group 3) and the group with no support (Group 1) (P=.4). In Group 1 (no support), leaks were localized in the corpus in five specimens, in the antrum in three specimens, and in the fundus in two specimens. In Group 2 (oversewing), seven specimens had leaks in the corpus, and three specimens had leaks in the fundus. In Group 3 (fibrin sealant [Tisseel]), leaks were found in the corpus of six specimens, in the antrum of two specimens, and in the fundus of two specimens. For specimens in all three groups, most of the leaks were detected in the corpus area (P=.007).

In Group 1 (no support material), leaks were detected in the junction points between sequential staple applications in four specimens and on the staple line in six specimens. Similarly, in Group 2 (oversewing), two specimens had leaks in the junction points between sequential staple applications, five had leaks on the staple line, and three had leaks in the serosal suturing localization. In Group 3 (fibrin sealant [Tisseel]), leaks were detected in the junction points between sequential staple applications in five specimens and on the staple line in five. Thus leaks occurred significantly more frequently in the staple line than in the staple junction points (P=.014) (Table 2).

Table 2.

Comparison of the Outcome Parameters

	Group 1 (n=10) (control)	Group 2 (n=10) (oversew suture)	Group 3 (n=10) (Tisseel)	P
Burst pressure (mm Hg)	30.5±3.06	106±10.5	28±5.09	<.01
Anatomic localization of leak				.007
Antrum	3	0	2
Corpus	5	7	6
Fundus	2	3	2
Stapler localization of leak				.014
Staple–junction points	4	2	5
Staple line	6	5	5
Serosal suturing localization	0	3	0

Data are mean±standard deviation values or number of patients as indicated.

Discussion

Sleeve gastrectomy is a popular weight loss operation²¹ that is becoming more popular as a “single stage” operation.^22,23 An endoscopic stapler is an indispensable instrument in bariatric surgery. However, there are several complications that can stem from stapler use, such as technical failure, bleeding, leakage, and fistula formation. It is generally challenging to define the causes of complications, as they can stem from the equipment type, the surgeon, or gastric tissue quality.⁵ Stapler equipment has evolved over time. New-generation staplers are designed to have three rows of staples for both sides of the tissue. However, most surgeons continue to use support materials to increase staple-line reinforcement.¹⁷ Ideally, these support materials enhance the anastomosis strength and reduce complications arising from staple-line failure. Many surgeons use different techniques, but a standard technique has not yet been established. One of the early gastric leak etiologies is believed to emanate from high intraluminal pressures, which tend to split the staple line.^5,24,25 To our knowledge, there have not been any previously published studies regarding the evaluation of the burst pressure caused by reinforcement techniques. Therefore, in this study, we aimed to compare the burst pressures of different reinforcement methods.

In bariatric surgery, leaks are known to be caused by tissue ischemia and/or staple-line mechanical disruption. Ischemic leaks appear later than leaks caused by mechanical disruption, which are generally seen within 2 days after surgery.²⁴ This might be attributed to the separation of the staple line, which is caused by high intraluminal pressure after the operation.⁵ Ischemic leaks occur during scar formation, which is the stage between the inflammatory and fibrotic phase (around 5–7 days postoperatively). Because the leaks seen in the first 48 hours are often due to mechanical disruption,²⁴ using support materials for reinforcement is a reasonable option. Although the use of support materials reduces the risk of technical failure, it does not prevent leaks due to ischemia.²⁶ Skikora²⁷ reported that support materials reduce bleeding and leaks. Lee et al.²⁸ and Ser et al.²⁹ also reported that fibrin sealants and buttressing materials reduce the risk of leaks and staple-line failure. Assalia et al.³⁰ used bovine pericardium buttressing material but did not report a decrease in the rate of complications.

Chen et al.³¹ are not in favor of using routine reinforcement methods. A few studies have examined the effects of reinforcement techniques on burst pressure in animal experiments: one reported that support materials were insufficient,³⁰ whereas the others found that the burst pressure was increased by reinforcement techniques.^18,32

As previously mentioned, there are various reinforcement methods for the staple line. In this study, we examined the effects of fibrin sealant (Tisseel) and serosal continuous suture on burst pressure. Fibrin glue sealant is a material that is mainly used to control bleeding and for the prevention of anastomosis leak. Silecchia et al.^33,34 reported that fibrin sealant (Tisseel) use could be beneficial for leak prevention. In our study, there was no significant difference between the fibrin sealant (Tisseel) group and the control group. However, burst pressure was higher in the group with continuous serosal suture compared with the fibrin sealant (Tisseel) and control groups.

It has been reported that most leaks are found in the staple-line junction points.⁵ In this study, we showed that leaks were mostly localized on the staple line. Moreover, most of these leaks were found in the corpus. In the study group with continuous serosal suturing (Group 2), leaks were detected on the serosal suture line in three specimens, but only after the application of high pressure.

To standardize the procedure, all patients whose gastrectomy specimens had disrupted staple-line integrity and those with damaged serosa (from the removal from the 15-mm trocar) were excluded from the study. Thus, the effect of damaged tissue on burst pressure could be excluded.

This study had some limitations. First, the effects of the various support techniques on bleeding could not be evaluated because of the in vitro design of the experiments. Second, we assumed that staple-line distension affected the resected stomach and the sleeve gastrectomy at a similar rate. We believe this is a reasonable assumption because the staples located in six rows in modern staple equipment are distributed equally between the removed and the remaining tissue.

Conclusions

There are many reports on the use of reinforcement techniques in the literature. However, the efficiency of these techniques is controversial. In this study, we showed that oversewing the staple line with 3-0 Vicryl suture significantly increased the strength of the staple line. Increases in intraluminal pressure are known to be one of the significant risks in leak etiology. Thus, we concluded that oversewing the staple line with 3-0 Vicryl suture may be beneficial in the prevention of leaks. However, further work is necessary in this area of research.

Footnotes

Disclosure Statement

No competing financial interests exist.

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