Evaluation of a bioresorbable hyaluronate-carboxymethylcellulose membrane for prevention of experimentally induced abdominal adhesions in horses

Successful treatment of sclerosing encapsulating peritonitis in a cat using bioresorbable hyaluronate-carboxymethylcellulose membrane after surgical adhesiolysis and long-term prednisolone

Case summary

An 8-year-old neutered male domestic shorthair indoor cat was presented with an 8-week history of intermittent vomiting, anorexia and weight loss that had been unresponsive to supportive treatment. Abdominal ultrasound revealed plication of the small intestine and fluid accumulation proximal to the lesion, and a linear foreign body was suspected. An exploratory celiotomy showed cocoon-like encapsulation of the entire intestine. Surgical adhesiolysis and full-thickness biopsy were performed, and histopathologic examination revealed mild thickening of the visceral peritoneum with fibrin deposition, as well as mild neutrophil and lymphocyte infiltration. These findings were compatible with sclerosing encapsulating peritonitis (SEP). The cat recovered well postoperatively and was discharged the next day. Prednisolone was administered for 7 weeks to prevent recurrence of SEP. Five months after surgery, the cat was re-presented with anorexia and chronic vomiting. Based on the clinical examination findings, recurrent SEP was suspected. At the second surgery, surgical adhesiolysis was repeated and a bioresorbable hyaluronate-carboxymethylcellulose membrane was used to cover the serosal surface and thus prevent adhesion formation. Histopathologic findings of the peritoneal biopsy specimen confirmed SEP. Long-term prednisolone treatment (1 mg/kg for the first dose and 0.5 mg/kg every 48 h for maintenance) was administered postoperatively. The cat survived for more than 1239 days without recurrence.

Relevance and novel information

To our knowledge, this is the first report of SEP in a cat with long-term survival. The use of a bioresorbable hyaluronate-carboxymethylcellulose membrane and long-term prednisolone treatment may have prevented short-term and long-term recurrence, respectively, in this case.

Effects of hyaluronate-carboxymethylcellulose membranes on the clinical outcome of horses undergoing emergency exploratory celiotomy

OBJECTIVE

To determine the influence of hyaluronate-carboxymethylcellulose (HA-CMC) membranes applied to intestinal anastomoses or enterotomies on postoperative complications after emergency exploratory celiotomy.

STUDY DESIGN

Multicenter retrospective case-controlled series.

ANIMALS

Adult horses (59 in the HA-CMC group and 91 controls).

METHODS

Medical records from 4 referral hospitals were searched for horses ≥1 year of age, treated between 2008 and 2014 with emergency exploratory celiotomy, and surviving at least 24 hours postoperatively. Horses receiving repeat celiotomy during the same hospitalization were excluded. Horses who received HA-CMC were matched with controls who did not receive HA-CMC but had similar intestinal lesions and procedures at the same referral hospital. Postoperative complications (colic, nasogastric reflux, fever, incisional infection, and septic peritonitis), duration of hospitalization, and survival were compared between groups. Data were compared between horses by t test, Wilcoxon signed rank test, and χ² test.

RESULTS

The volume of nasogastric reflux at admission (P = .02) and the duration of administration of lidocaine after surgery (P = .02) were greater in horses with HA-CMC membranes than in controls. No difference in postoperative complications or survival was detected between groups: 48 of 59 (81%) horses treated with HA-CMC survived until discharge from the hospital compared with 80 of 91 (88%) horses in the control group (P = .27). Fifteen of 21 horses treated with HA-CMC and 30 of 43 horses in the control group survived >12 months after hospital discharge.

CONCLUSION

Application of HA-CMC membranes to anastomoses or intestinal incisions did not influence postoperative complications or survival after emergency celiotomy compared with controls.

CLINICAL SIGNIFICANCE

The safety and efficacy of HA-CMC membrane application to intestinal sites during colic surgery in horses is equivocal.

Intra-abdominal hyaluronan concentration in peritoneal fluid of horses with sudden signs of severe abdominal pain

OBJECTIVE

To determine hyaluronan concentrations in peritoneal fluid from healthy horses and horses with sudden signs of severe abdominal pain and to identify the cellular sources of hyaluronan within the peritoneal cavity.

ANIMALS

7 client-owned horses that were evaluated for sudden signs of severe abdominal pain, 6 healthy teaching horses, and 13 euthanized horses (11 with no abdominal disease and 2 that had undergone abdominal surgery 2 weeks previously for a different study).

PROCEDURES

Abdominal fluid was collected from the client-owned and teaching horses. Hyaluronan concentrations were determined with an ELISA. Equine mesothelial cells were aseptically harvested from euthanized horses immediately after euthanasia, cultured, and processed for western blot immunoassays to detect expression of the following mesothelial cell markers: cytokeratins 8 and 18, vimentin, calretinin, mesothelin, and CD44. A reverse transcriptase-PCR assay was used to detect genetic expression of hyaluronan synthase-2 (HAS-2) from cultured and native equine tissue.

RESULTS

The mean ± SD abdominal hyaluronan concentration in peritoneal fluid from horses with signs of abdominal pain (1,203.3 ± 46.3 ng/mL) was significantly greater than that in healthy horses (228.4 ± 167.3 ng/mL). Harvested cells were maintained, and immunoblotting analyses confirmed expression of the mesothelial markers. Gene expression of HAS-2 from cultured mesothelial cells and fibroblasts was confirmed.

CONCLUSIONS AND CLINICAL RELEVANCE

Peritoneal hyaluronan concentration was much higher in horses with severe abdominal pain than in healthy horses. Cultured equine mesothelial cells and fibroblasts can produce hyaluronan through HAS-2. Future investigation should focus on establishing the effect of exogenous hyaluronan administration on mesothelial cell function in horses with abdominal disease.

Peritoneal adhesions in human and veterinary medicine: from pathogenesis to therapy. A review

Any peritoneal inflammatory process consequent to infections or surgical injuries may induce abdominal adhesion formation. Peritoneal adhesions are connective laciniae that develop among abdomino-pelvic organs that limit physiologic visceral motion. Consequently, fertility may be impaired, and intestinal obstruction and pelvic pain may develop, mainly in subjects that had undergone gynaecological surgery. This review illustrates the pathogenic steps of adhesiogenesis and the therapeutic scenario that evolved over the years to tackle the threat of peritoneal adhesions, both in domestic animals and in women.

Postoperative Pericardial Adhesion Prevention Using Carbylan-SX in a Rabbit Model

INTRODUCTION

The presence of dense adhesions within the pericardial space complicates reoperative cardiac surgery. Prior attempts to reduce adhesion formation after primary cardiac surgery using medications or biomaterials have had variable success. Carbylan-SX (Carbylan Biosurgery Inc., Palo Alto, CA) is a hyaluronan-based biomaterial, which has been shown to be effective at reducing adhesions in a nonthoracic rat model. This study evaluates whether Carbylan-SX can effectively reduce postoperative adhesions within the pericardial cavity.

METHODS

Thirty-eight New Zealand white rabbits underwent a left lateral thoracotomy. A pericardiotomy was made and epicardial adhesions were induced on the anterior surface of the heart using a Dremel device (Racine, WI). The rabbits were divided into four groups: controls with abrasions only receiving no treatment (n=10), Carbylan-SX films (n=10), Carbylan-SX aerosolized hydrogel (n=10), and Seprafilm (n=8). The pericardial sac and chest were subsequently closed. Rabbits were sacrificed at a mean of 15 days. For histological analysis, each heart was divided into 12 separate 1 mm sections. Computer imaging software was used to measure the adhesion thickness and the mean of 12 random measurements for each animal was recorded and statistical analysis performed.

RESULTS

Histological analysis revealed all treatment groups to be significantly better than the control (2159 mum thickness, P<0.0001) at preventing adhesions. The Carbylan-SX film and Carbylan-SX aerosolized hydrogel both proved to be better at preventing adhesions than Seprafilm (Genzyme Corp., Cambridge, MA) with an average adhesion thickness of 454 and 577 microm, respectively, compared with 1319 microm for Seprafilm (P<0.0001 and P<0.0005, respectively). The Carbylan-SX film and Carbylan-SX aerosolized hydrogel were equally effective at preventing adhesion formation.

CONCLUSION

Carbylan-SX film and Carbylan-SX aerosolized crosslinkable hydrogel are equally effective methods of reducing postoperative pericardial adhesions within the pericardial cavity. Both the Carbylan-SX film and aerosolized hydrogel showed a significantly greater reduction in adhesions than Seprafilm. Clinical application of Carbylan-SX could have significant therapeutic implications in the future.

Reduced postoperative intra-abdominal adhesions using Carbylan-SX, a semisynthetic glycosaminoglycan hydrogel

OBJECTIVE

To compare the efficacy of crosslinked Carbylan-SX (Carbylan BioSurgery, Inc., Palo Alto, CA) hydrogel films and sprayable gels as physical barriers in reducing postoperative intra-abdominal adhesions in the rat cecum-abdominal wall and rat uterine horn models.

DESIGN

Pre-formed crosslinked Carbylan-SX films and sprayable in situ crosslinkable Carbylan-SX gels were evaluated in rat cecum-abdominal wall and rat uterine horn models and compared with commercially available and clinically used Seprafilm.

SETTING

University animal research facility.

ANIMALS

Female Wistar rats.

INTERVENTION(S)

Abrasions were made with the foot-pedal-operated Flex-shaft (Dremel, Racine, WI) on both the cecum and abdominal wall (each area 10 mm in diameter) in female rats as one model and on both uterine horns (3 x 10 mm) in female rats as the other model. In each of the two adhesion models, four groups were assigned with eight rats in each group: (1) untreated control, (2) treated with Seprafilm (Genzyme Corporation, Cambridge, MA), (3) treated with preformed Carbylan-SX hydrogel films, and (4) treated with sprayable Carbylan-SX gel.

MAIN OUTCOME MEASURE(S)

Extent and severity of postoperative adhesions between the cecum and the abdominal wall in rat cecum-abdominal wall model and between the uterine horns in rat uterine horn model.

RESULT(S)

The Carbylan-SX film and the Carbylan-SX sprayable gel led to fewer adhesions than Seprafilm in both rat adhesion models. Interestingly, a single physical form was not optimal for both models: the Carbylan film was more efficacious in the rat uterine horn model, whereas Carbylan gel gave the best results in the rat cecum-abdominal wall model.

CONCLUSION(S)

Both Carbylan-SX film and gel were efficacious in reducing postoperative intra-abdominal adhesion formation in rat cecum-abdominal wall and uterine horn models.

Recent advances in equine abdominal surgery

Laparoscopy is a minimally invasive procedure that has applications as a diagnostic, therapeutic and prognostic technique. Specialized equipment is necessary to perform equine laparoscopy, and there is a large range of instruments, both disposable and non-disposable available. Laparoscopic procedures described include ovariectomy, cryptorchidectomy, adhesiolysis and herniorrhaphy. Laparoscopy can be performed in a standing or dorsally recumbent position, depending on surgeon preference, patient status and the procedure to be performed. Stapling equipment is frequently used in gastrointestinal surgery in horses. Advantages include decreased surgical time and a decrease in the risk of contamination. Stapling equipment is often used in creating anastomoses, both in the large and small intestines, as well as in vessel ligation. New surgical techniques intended to decrease adhesion formation include the use of carboxymethylcellulose and bioresorbable patches. Indwelling abdominal drains can be used for peritoneal lavage following surgery and also appear to decrease the risk of adhesion formation. Improvements in post-operative care, including the treatment of post-operative ileus and endotoxaemia can significantly improve the outcome of horses that have undergone surgery for abdominal disorders. Recommendations for the use of prokinetic agents in horses with ileus vary widely. Prokinetic agents include local anaesthetics, macrolide antimicrobials, cholinergic agonists and dopamine antagonists. Endotoxaemia is common in horses following surgery for gastrointestinal disorders. The antibiotic polymyxin B binds to the circulating endotoxin molecule, decreasing its half-life in the intra-vascular space and reducing associated inflammation. This drug appears to be an effective and affordable treatment option for horses with endotoxaemia. The use of specific cyclooxygenase inhibitors in veterinary medicine have been studied recently. Selective cyclooxygenase-2 inhibitors may provide comparable anti-inflammatory and analgesic properties to the non-selective non-steroidal anti-inflammatory drugs. These drugs appear to have similar clinical effectiveness and will hopefully minimize deleterious side effects. The optimal healing of ventral midline incisions in horses is related to many factors including appropriate suture patterns and bite size, in addition to appropriate post-operative exercise recommendations. Recent advances in surgical techniques and post-operative care should decrease the morbidity and mortality associated with abdominal surgery. This article provides an overview of some of these advances.

Comparison of two laparoscopic treatments for experimentally induced abdominal adhesions in pony foals

OBJECTIVE

To compare laparoscopic dissection with-laparoscopic dissection combined with abdominal instillation of ferric hyaluronate gel for the treatment of experimentally induced adhesions in pony foals.

ANIMALS

12 healthy pony foals.

PROCEDURE

A serosal abrasion method was used to create adhesions at 4 sites on the jejunum (day 0). At day 7 laparoscopy was performed and the adhesions observed in each foal were recorded. In group-1 foals (n = 6), the adhesions were separated laparoscopically (treatment 1). In group-2 foals (n = 6), 300 mL of 0.5% ferric hyaluronate gel was infused into the abdomen after the adhesions were separated laparoscopically (treatment 2). At day 24, terminal laparoscopy was performed and the adhesions observed were recorded. Total number of adhesions within each group was compared between day 7 and 24. Data were analyzed to determine whether an association existed between the number of adhesions on day 24 and treatment type.

RESULTS

At day 24, the number of adhesions was significantly decreased within each group, compared with the number of adhesions at day 7 (group-1 foals, 10 vs 22 adhesions; group-2 foals, 3 vs 20 adhesions). Treatment 1 was associated with a significantly higher number of adhesions at day 24, compared with treatment 2 (odds ratio, 4.54; 95% confidence interval, 1.03 to 23.02).

CONCLUSION AND CLINICAL RELEVANCE

Abdominal instillation of 0.5% ferric hyaluronate gel after laparoscopic dissection was a more effective technique than laparoscopic dissection alone to treat experimentally induced adhesions in pony foals. Laparoscopic adhesiolysis following abdominal surgery in foals is a safe and effective technique.

Effect of carboxymethylcellulose and hyaluronate solutions on jejunal healing in horses

OBJECTIVE

To compare a double-layer inverting anastomosis with a single-layer appositional anastomosis, coated with either 1% sodium carboxymethylcellulose (SCMC) or 0.4% sodium hyaluronate (HA) solutions, in the small intestine of horses with respect to anastomotic healing and adhesion formation.

ANIMALS

18 adult horses.

PROCEDURE

Midline celiotomy and end-to-end jejunal anastomoses were performed. In control group horses (n = 6), a double-layer inverting anastomosis coated with sterile lactated Ringer's solution was performed. In treatment group horses, a single-layer appositional anastomosis was performed that was coated with 1% carboxymethylcellulose solution (SAA + SCMC group horses, 6) or 0.4% hyaluronate solution (SAA + HA group horses, 6). An additional 500 mL of the respective treatment solution was applied to the jejunal serosal surface, and 2 jejunal serosal abrasion sites were created. Horses were euthanatized 10 days after surgery. Anastomoses and abdominal adhesions were evaluated grossly. Anastomotic healing was evaluated on the basis of bursting wall tension.

RESULTS

Bursting wall tension was significantly greater in SAA + SCMC group horses, compared with control group horses. All intestinal segments failed at a point distant to the anastomosis. Significantly fewer adhesions were found at the abrasion sites of SAA + HA group horses, compared with control group horses. No differences were found in adhesion formation at the anastomotic sites among groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Coating a single-layer appositional jejunal anastomosis with SCMC or HA solutions does not adversely affect anastomotic healing. Application of 0.4% HA solution to the serosal surface of the jejunum significantly decreases the incidence of experimentally induced intra-abdominal adhesion formation in horses.

Prevention and treatment of gastrointestinal adhesions

As with many aspects of clinical medicine, there is yet to be a single or definitive cure for postoperative adhesion formation. Current methods of prevention target risk factors predisposing horses to adhesion formation. Systemic pharmacologic therapies, such as antimicrobials, nonsteroidal anti-inflammatory drugs, Salmonella antiserum, and hyperimmune plasma, help to reduce abdominal inflammation and minimize the effects of endotoxemia. Intra-abdominal or systemic heparin aids in enhancing peritoneal fibrinolysis. Prokinetic therapy promotes early postoperative return of intestinal motility, minimizing the propensity for adhesion formation between apposing adynamic segments of intestine. Mechanical separation of potentially adhesiogenic serosal and peritoneal surfaces is commonly achieved with use of abdominal lavage, protective coating solutions, and barrier membranes. Ongoing and future research is directed toward a better understanding of the local effects of intestinal trauma and the corresponding response of the fibrinolytic system. Recognition of horses at high risk for adhesion formation helps to guide the equine surgeon to an appropriate perioperative and intraoperative plan for adhesion prevention, including good surgical technique and a combination of adjunct therapies.

Carboxymethylcellulose coated on visceral face of polypropylene mesh prevents adhesion without impairing wound healing in incisional hernia model in rats

Adhesions between viscera and mesh may result in intestinal obstruction and fistulae formation. Fewer adhesions with sodium carboxymethylcellulose (SCMC)-coated polypropylene mesh (PM) has been reported, but impaired wound healing was the major concern. We investigated the adhesion-prevention effect of SCMC in different concentrations, as coating only on visceral face of PM and its effects on wound healing. A full-thickness abdominal wall defect was created in 28 rats, which were then divided into three groups. In Group I (control), the defect was repaired with PM only; in Group II and Group III, the defects were repaired with 1% and 1.6% SCMC-coated-PM, respectively. All animals were sacrificed at day 30, and histological evaluation and adhesion scoring were done. Animals in the group in which 1.6% SCMC-coated PM was used developed significantly fewer adhesions compared with other animals (P=0.04). Histological evaluation using a semiquantitative scoring system showed no difference between the groups in fibrosis and inflammation scores (P=0.9 and P=0.3, respectively), and thickness of fibrosis on mesh was also similar (P=0.5). SCMC in 1.6% concentration as coating only on the visceral face of PM reduced the incidence and severity of adhesions without impairing wound healing.

Combined therapy of allantoin, metronidazole, dexamethasone on the prevention of intra-abdominal adhesion in dogs and its quantitative analysis

AIM: To observe the preventive effects of combined therapy of AMD (allantoin, metronidazolem and dexamethasone in combination) on intra-abdominal adhesion in dogs.

METHODS: 20 dogs of both sexes were used in this study. After laparotomy under anesthesia, 2 cm section of cecal end was clamped and ligated, then 1 cm cecum section was cut and another 1 cm was kept. The cecum stump was closed with purse-string suture. Both parietal and visceral peritonea were stripped for an area of about 3 × 4 cm². Before the skin closure, the animals were divided into two groups randomly. The abdominal cavities in Group AMD (n = 10) were rinsed by 200 mL of AMD solution, and with 50 mL left, whereas the control (n = 10) received the equal volume of normal saline. After 7 d, the degree of intra-abdominal adhesions was evaluated by using the score method of ultrasonography and traditional dissection.

RESULTS: Compared with the control, both the ultrasonography and traditional dissection scores in Group AMD were significantly decreased that marked as 2.0 ± 1.25 vs 3.3 ± 0.82 and 1.91 ± 0.83 vs 3.3 ± 0.82 respectively (P < 0.01).

CONCLUSION: The combined therapy of AMD is an effective way to prevent intra-abdominal adhesion, and ultrasonography is an useful tool to diagnose intra-abdominal adhesion.

Evaluation of laparoscopic adhesiolysis for the treatment of experimentally induced adhesions in pony foals

OBJECTIVE

To assess the efficacy of laparoscopic adhesiolysis in the treatment of experimentally induced adhesions in foals.

ANIMALS

8 healthy pony foals.

PROCEDURE

Celiotomy was performed and adhesions created at the jejunoileal junction and at sites 0.5 and 1 m proximal to this junction, using a serosal abrasion method. Ten days after celiotomy, exploratory laparoscopy was performed. Laparoscopic adhesiolysis was performed in the treatment group only (4 foals, randomly selected). Thirty days after the exploratory laparoscopy, a final laparoscopic examination was performed, and the foals were euthanatized. The number and characteristics of abdominal adhesions were recorded during laparoscopy 10 and 30 days after celiotomy and during necropsy.

RESULTS

At 30 days after celiotomy, the number of adhesions in the control group was significantly higher than the number in the treatment group. In the control group, all adhesions observed during the exploratory laparoscopy were still evident at the final laparoscopy and necropsy. In the treatment group, adhesions did not form again after separation. During final laparoscopy and necropsy, a focal adhesion between the omentum and site of the initial laparoscope portal was observed in 5 of 8 foals.

CONCLUSIONS AND CLINICAL RELEVANCE

The serosal abrasion model is useful for studying abdominal adhesions in foals. Laparoscopic adhesiolysis was an effective technique to break down experimentally induced adhesions in the early maturation stage of formation in pony foals. Studies are required to investigate prevention of de novo adhesions at the laparoscope portal sites.

Use of a hyaluronate membrane for jejunal anastomosis in horses

OBJECTIVE

To compare the outcomes of double-layer inverting anastomosis (DIA), single-layer anastomosis (SLA), and single-layer anastomosis combined with a hyaluronate membrane (SLA+HA-membrane) with respect to stomal diameter, adhesion formation, surgery time, and anastomotic healing in horses.

ANIMALS

18 adult horses.

PROCEDURE

Midline celiotomy and end-to-end anastomoses were performed. In control horses (n = 6), DIA was performed; in treated horses, SLA was performed (6) or SLA+HA-membrane was performed (6). Horses were euthanatized 21 days after surgery. Abdominal adhesions were evaluated grossly and histologically. Stomal diameters were measured ultrasonographically and compared with adjacent luminal diameters. Anastomotic healing was evaluated histologically for fibrosis and inflammation, tissue alignment, and inversion. Surgery times were recorded for the anastomotic procedure and compared among groups.

RESULTS

There were significantly more adhesions in the SLA group, compared with the DIA and SLA+HA-membrane groups. Reduction in stomal diameters in the DIA group was significantly greater than the SLA and SLA+HA-membrane groups. Surgery times for the DIA group were significantly greater than the SLA and SLA+HA-membrane groups. Histologic findings of fibrosis, inflammation, and mucosal healing were similar among groups. There was significant tissue inversion in the DIA group, compared with the 2 treatment groups. Tissue alignment was not different among groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Use of a SLA+HA-membrane was an effective small intestinal anastomotic technique. This technique was faster to perform and resulted in a larger stomal diameter, compared with the DIA technique and significantly fewer perianastomotic adhesions, compared with the SLA technique.