JSUR Journal

Introduction

A common risk during surgery is the possibility of incompletely secured blood or lymphatic vessels. Inadequate closure of vessels can lead to clinically, even life-threatening, bleeding or fluid accumulation. During surgery, the ligation of blood or lymph vessels with ligating loops or stitched ligature can be time consuming and sometimes challenging [1,2]. There are several surgical options for achieving adequate ligation of tubular structures such as hemostatic agents, electrocautery, surgical intervention with sutures or ligation clips. Advantages and disadvantages are associated with each approach and the choice depends upon the anatomic area of use and surgery indications and contraindications. Compared to the above therapies, there are no patient characteristics that limit or define the use of clips. Studies have shown that the use of endoscopic clips decrease operative time, and they do not have the potential to cause thermal injury since clips do not heat tissue,[3] or lead to smoke exposure [4,5] Adverse effects of using hemostatic agents include incomplete product absorption, inflammation, and granuloma formation. In addition, neurologic manifestations may result from either direct neurotoxicity or unintended compression of adjacent neural structures [6].

Ethicon’s Ligaclips are made of a biocompatible titanium alloy and are available in a variety of sizes. The clips work by closing opposing clip arms thereby clamping the vessel and/or producing vascular compression. Ethicon’s clip appliers and clips are designed to deliver superior retention, efficient ligation and minimal vessel damage. Ligaclip Single-Clip Appliers (SCA’s) are reloaded after each application, and may be re-sterilized for multiple uses. SCA’s are available in Open and Endoscopic (for 12 mm trocars) versions. Ligaclip Multi-Clip Appliers (MCA’s) can be loaded with up to 30 clips that automatically advanced after each application. MCA’s are available in Open and Endoscopic (for 12 mm trocars) versions. Ligamax 5 can also deliver multiple clips, but is designed to fit 5 mm trocars. The Endoscopic versions of Ligaclip MCA and Ligamax 5 have heads that can fully rotate by 360° for improved access. Both Ligaclip MCA’s and Ligamax 5 are single-use devices, and cannot be re-sterilized.

Figure 1: Ligamax 5 Clip Applier.

When clips are properly applied and secured, leakage of fluid, such as blood or bile is prevented.[7] Ultimately, the tissue or vessel occluded by the clip is permanently stenosed and following inflammatory reactions, sealed by normal healing processes. Clips have been known to come off the ducts or vessels to which they have been applied, especially if they have not been fully closed. Clips have been observed being dislodged as they were being placed and immediately after they had been placed. These clips can also become dislodged from the severed end of the duct or vessel. If the vessel lumen is not effectively occluded, bile or blood is free to leak into patients postoperatively. The formation of fluid collections or hematomas may occur, potentially necessitating surgical re-exploration, blood transfusions, or other interventions. It is essential that clips have a high retention force and low rate of clip scissoring to reduce the risk of slippage or leakage after application. This study aimed to provide benchtop data to evaluate the retention force and closure for both Ligaclip MCA and Ligamax 5 Endoscopic MCA (Figure 1) compared to other conventional clip appliers.

Methods

Comparisons of functionality and physical characteristics were performed between Ligaclip MCA (MCS20, Ethicon, Cincinnati OH) and Premium Surgiclip S-9.0 (134046, Medtronic, Minneapolis MN). Clip gap was measured at the proximal end for fully formed clips fired in air (Figure 2). Axial and transverse clip retention (Figure 3) were measured on micro-polyurethane tubing (BB520-50, 1.0 mm I.D, 1.4 mm O.D, Scientific Commodities, Inc, Lake Havasu City, AZ). Pull-off force was measured using an Instron Test System with a 9 Newton load cell (Instron Corp, Norwood MA). Axial and transverse clip retentions were compared between Ligamax 5 Endoscopic Multiple Clip Applier (EL5ML, Ethicon, Cincinnati OH) and Epix Universal Clip Applier (CA500, Applied Medical, Rancho Santa Margarita, CA). Two clips from each device were tested for axial clip retention and two for transverse clip retention. For axial retention, the clip applier was used on micro-polyurethane tubing (BB520-50, 1.0 mm I.D, 1.4 mm O.D, Scientific Commodities, Inc, Lake Havasu City, AZ). For transverse retention, the clip applier was used on Silastic tubing (508-011, 3.4 mm I.D, 4.6 mm O.D, Dow Silicones, Midland, MI). Pull-off force was measured using pneumatic grips attached to a 44 Newton load cell with a pull rate of 5 cm/min. Statistical comparisons were performed via Student’s t-test or Mann-Whitney if the data were non-normal, with an alpha of 0.05.

Figure 2: Proximal gap of a formed clip.	Figure 3: Direction of axial and transverse pull-off of clip relative to the blood vessel.

Results

Ligaclip MCA had a 36% smaller proximal gap than Surgiclip. Ligaclip MCA had a 43% higher axial retention force and a 46% higher transverse retention force than Surgiclip (Table 1, Figure 4). Axial retention force Ligamax 5 was 122% greater than the axial retention force for Epix, while Epix had a 28% higher transverse retention force (Table 2, Figure 5).

Table 1: Summary of comparisons of Ligaclip MCA and Premium Surgiclip.

Figure 4: Axial and transverse retention forces for Ligaclip MCA and Premium Surgiclip. Error bars represent 95% confidence interval of the mean.

Table 2: Summary of comparisons of Ligamax 5 and Epix.

Figure 5: Axial and transverse retention forces for Ligamax 5 and Epix. Error bars represent 95% confidence interval of the mean.

Discussion

Endoscopic clips were first used in 1975 for the treatment of gastrointestinal bleeding. Since their introduction, there have been numerous design changes that have been made in terms of improving therapeutic efficacy and retention.[8] A clip should have a strong holding force while avoiding tissue damage or clip migration which may cause bleeding or bile leakage. A clip should also be fast to load, easy to apply, and cost effective. One surgical space that endoclips can have great utility in is for appendicular stump closure during laparoscopic appendectomy. Linear endostaplers, endoloops, bipolar coagulation, ultrasonic scalpels, intracorporeal knot tying, and endoclips are all methods that can be used for effective appendicular stump closure, but endoclips have been less commonly used despite the fact that they have been shown to simplify the procedure and are just as efficacious and safe as the other options.[9] Titanium endoclips have been shown to reduce operative time especially when compared to intracorporeal knot tying and are less costly than endostaplers. The titanium endoclip can also be safely applied to an inflamed appendix base, and studies show that it has been safely applied to appendiceal diameters of up to 20 mm.[10] Moreover, complication rates are similar between endoclips and the other methods of stump closure, making it a suitable choice for use in laparoscopic appendectomy [10].

Controlling the renal hilar vessels during laparoscopic nephrectomy is typically performed by laparoscopic staplers, however, several cases of stapler malfunction were reported necessitating the search for better alternative methods for controlling the renal pedicle. Chibber, et al, demonstrated that the 10mm Ligaclip can be used for adequate renal hilar control without any incidence of slippage or dislodgment of clips for the vast majority of patients. In addition, they are approximately 6-fold cheaper than plastic clips and 12-fold cheaper than the staplers, making the Ligaclip a much more cost effective method for renal hilar control.[11] Titanium clips for vascular control have been shown to be cost effective in laparoscopic nephrectomy. [7] With regards to the cost effectiveness of clip closure, Albeniz, et al, found that clipping after resection of large colon lesions can provide a cost saving,[12] and Usmani, et al, noted that in appendectomy, clips were a cost-effective alternative compared to endoloops and surgical ties.[13] In contrast to surgical procedures where there are numerous ways in which to achieve ligation of critical structures, endoclips are considered the gold standard for cystic artery and cystic duct ligation during laparoscopic cholecystectomy. One of the drawbacks of the metal endoclip is the possibility of surgical clip migration, but this is a very rare and oftentimes a late onset complication with less than 100 cases reported in the last 30 years.[14] Even though some studies have shown that using absorbable clips may be as safe and effective as metal endoclips, it appears that metal endoclips may be more beneficial for shorter cystic duct ligations due to the decreased likelihood of dislodgement [15].

Some metallic clips are known to slough off at 18-26 days after their application during gastrointestinal endoscopic procedures, whereas others will remain at their original site for up to a year.[16] Sloughing of metallic clips off vessels or ducts in the context of tissue healing has not been widely discussed in the surgical literature, but after endoscopy, it is reported that metallic clips can safely fall off and pass through the gastrointestinal tract within 3 weeks.[17] Tissue healing occurs in approximately 2-3 weeks in healthy individuals, allowing any vessels or mucosal defects that were clipped to heal effectively. Of note, tissue healing is likely to be prolonged for patients with several comorbidities or those undergoing additional treatments such as chemotherapy or radiation.

Figure 6 : Scissoring of a formed clip.

    Ligaclip Ligating Clips feature lateral and transverse grooves designed for secure fixation on the structure and increased resistance to     dislodgement of a formed clip. Both Ligaclip MCA and LigaMax have a higher axial retention compared to other commercially-marketed products.     The results observed in this study are in agreement with previous comparisons of clip retention.[18] If a clip is dislodged transversely prior to     transection of the vessel, it can be replaced prior to substantial blood loss. However, if after transection a clip were to fall off axially, there is a     potential for blood loss. Hence, the high axial retention force of Ligaclip appliers provides increased assurance that vessels will remain sealed     perioperatively and thereafter. Scissoring is a non-alignment of the legs of a closed clip (Figure 6) and an excessive amount of scissoring may     affect the integrity of the vessel sealing. Clips should have scissoring of less than half the width of a leg, typically about a half millimeter. Ligaclips     have exhibited mean scissoring of only 0.05 mm, a wide safety margin providing confidence in sealing.

    There are several devices that can be used for ligation of vessels, lymphatics, ducts, and tissue sealing, and both Ligaclip and Ligamax are tools     that can help effectively achieve these goals during laparoscopic or open surgery. The cost per procedure for surgical clips is typically lower than     other approaches. Ligating clips, while simple in concept, are a versatile tool for hemostasis that are frequently used when other standard     methods, such as staplers or energy devices, cannot be readily used.

References

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