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Surgical techniques for minimising adhesions in abdominal surgery
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Summary
Adhesions are one of the leading causes for long term morbidity and mortality in horses undergoing colic surgery, particularly in horses with small intestinal strangulating obstruction. The layer of mesothelial cells protecting the serosal surface of the intestine from injury is fragile, and easily disrupted during surgery. Once disrupted, it has been shown that neutrophils migrate to the site and induce an inflammatory reaction, including the presence of fibrin that makes the bowel ‘sticky.’ This is particularly the case in strangulating obstructions because ischemia and distension both increase the likelihood of serosal inflammation. Surgeons should try to minimize additional trauma to the intestine by careful handling, including keeping gloves moistened at all times, and using lubricant surface products, particularly carboxymethylcellulose. The latter can be applied at the beginning of surgery, and at the completion of surgery to serve as a barrier agent to reduce the likelihood of inflamed surfaces touching each other and forming fibrinous adhesions. Careful attention to surgical technique, including anastomoses with inverting suture patterns to reduce the presence of ‘raw’ edges to form adhesions, and incisional closure to reduce exposed suture within the abdomen is important. Other considerations relate to systemic medical therapy, including broad spectrum antibiotics and anti-inflammatory agents, which have been shown to reduce adhesions in experimental studies.
Key words: Carboxymethylcellulose, fucoidan, fibrinous, fibrous, neutrophil
Surgical technique and pathophysiology
Perhaps the most important component of reducing adhesions during abdominal surgery is the technique itself – meaning the less intestinal trauma the better. This is in consideration of the pathophysiology of adhesions. Research indicates that it takes minimal trauma to the intestinal surface to physically abrade the delicate serosal layer of mesothelial cells, exposing the connective tissue and muscular tissues beneath.(1) Over time, this results in an inflammatory cascade in which neutrophils are extravasated and line up along the serosal surface of the intestine. This in turn results in exudation of fibrin, making the surface of the intestine ‘sticky.’ When these sticky surfaces touch other traumatized areas of intestine, or sometimes even normal intestine, fibrinous adhesions may result. This may encourage additional inflammation, and ultimately infiltration of fibroblasts that may make the adhesion progressively fibrous and permanent. To limit surgical trauma, surgical gloves should always be moistened with saline, and carboxymethylcellulose (CBMC, 1% solution, 0.5-1L, IP) can be immediately poured into the abdomen once the midline incision has been completed. When manipulating the intestine, it should be cupped in the hand or cradled on the forearms as much as possible, rather than directly grasping the bowel wall itself. This all becomes much more difficult when there is an ischemic lesion, which together with distension, has been shown to markedly increase inflammation of the intestinal wall.(2) In addition, intestinal distension and strangulation in areas such as the epiploic foramen makes it difficult to manipulate the intestine carefully. During intestinal manipulation, there is also some consideration as to how much the small intestine should be emptied in order to reduce the possibility of postoperative ileus. It is generally agreed that emptying the small intestine outweighs the concerns related to the additional manipulation required. Therefore, small intestinal fluid needs to be ‘milked’ aborally, but if extensive, it can either be milked through the cut end of a resection site (strangulating obstruction) or via an enterotomy (simple obstruction, such as ileal impaction).
Use of barrier-forming agents to reduce adhesions
The most common barrier-forming agents used to reduce adhesions are CBMC and fucoidan. Both agents reportedly reduce formation of adhesions. In the case of CBMC, one study has shown that use of CBMC versus not using it at all reduces the incidence of postoperative colic and increases long-term survival, both suggestive of a reduction of adhesions.(3) Numerous preclinical trials have also shown a benefit of CBMC.(4) It does make the bowel slippery and a little more difficult to handle, but placement in the abdomen at the beginning of surgery and depositing an additional 250-500ml at the end of surgery is the most common method of administering the compound. Additional CBMC can be used during surgery if trauma and inflammation of the bowel appears to be progressing.
Incisional technique and closure
Adhesions can occur anywhere within the abdomen, between any of the organs. The midline incision is one of the most common sites of adhesions, indicating that care making the midline incision is important. This should include an incision through the linea alba to reduce exposure of the rectus muscle during closure, and leaving as smooth a surface as possible when closing the abdomen. There has been some discussion in the past about whether or not to close the peritoneum, but this has been abandoned because it is a relatively difficult layer to suture at the end of a procedure, and leaves more suture within the abdomen. As far as the closure, most surgeons are presently using continuous suture patterns, which likely leaves less suture exposed. Although monofilament suture is also more desirable than multifilament suture from the standpoint of leaving rough edges within the abdomen, many surgeons are concerned about the brittle nature of monofilament suture such that it is thought to put horses at greater risk of incisional dehiscence. This author presently uses 6 metric polyglacin-910.
Anastomotic and enterotomy techniques
To avoid exposure of edges of tissue that may form the site of an adhesion, care is taken to invert seromuscular tissues wherever possible. For enterotomies of the large colon, which can become adhered, typical suture patterns include a simple continuous suture pattern of the mucosa followed by a continuous Cushing pattern in the seromuscular layer. This same pattern can be used in end-to-end anastomoses of the small intestine, although more recently a one stage continuous Lembert has been used. The latter technically reduces time and forms a good seal, but does leave a little more suture exposed than the Cushing pattern. Sutures at the mesenteric and antimesenteric sides of the anastomosis can be inverted or ‘buried’ to prevent tags of suture from being exposed. Additionally, most surgeons recommend closure of the mesentery.
Medical considerations
Systemic inflammation, particularly within the abdominal cavity, is thought to increase the onset of adhesions, perhaps explaining why some horses develop a mass of adhesions despite the apparent lack of abraded surfaces. This has been shown to be offset by systemic use of broad spectrum antibiotics (K-penicillin, 22,000 IU/ Kg, IV, q6h, and gentamicin 4-6mg/kg, IV, q24h), and anti-inflammatory drugs (flunixin meglumine, 1.1mg/kg IV, q12h or firocoxib, 0.3mg/kg IV, loading dose, 0.1 mg/kg IV q24h). In the original study evaluating this regime, DMSO was also included,(5) but this has since been abandoned by most surgeons. It is also conceivable that because lidocaine (1.3mg/kg loading dose, 0.05mg/kg/min, IV, CRI) reduces mucosal inflammation it may also reduce transmural inflammation, but this has not been fully investigated.
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- Get unlimited access to books, proceedings and journals.
- Get access to a global catalogue of meetings, on-site and online courses, webinars and educational videos.
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[1] Little D, Tomlinson JE, Blikslager AT. Post operative neutrophilic inflammation in equine small intestine after manipulation and ischaemia. Equine veterinary journal. 2005;37(4):329-35.
[2] Lundin C, Sullins KE, White NA, Clem MF, Debowes RM, Pfeiffer CA. Induction of peritoneal adhesions with small intestinal ischaemia and distention in the foal. Equine veterinary journal. 1989;21(6):451-8.
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