Evaluation of the Effectiveness of Peritoneal Adhesion Prevention Devices in a Rat Model

An injectable and antifouling hydrogel prevents the development of abdominal adhesions by inhibiting the CCL2/CCR2 interaction

Abdominal adhesion, a serious complication of abdominal surgery, often resists mitigation by current drug administration and physical barriers. To address this issue, we developed an injectable, antifouling hydrogel through the free-radical polymerization of methacrylate chondroitin sulfate (CS-GMA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) monomers, dubbed the CGM hydrogel. We systematically analyzed its physicochemical properties, including rheological strength, biocompatibility, and antifouling capabilities. A rat abdominal cecum adhesion model was constructed to assess the effectiveness of CGM hydrogel in preventing postoperative adhesion and recurrent adhesion. In addition, multi-omics analyses identified the relationship between adhesion development and CCL2/CCR2 interaction. Notably, CGM hydrogel can thwart the recruitment and aggregation of fibroblasts and macrophages by inhibiting the CCL2/CCR2 interaction. Moreover, CGM hydrogel significantly dampens the activity of fibrosis-linked cytokines (TGF-βR1) and recalibrates extracellular matrix deposition-related cytokines (t-PA and PAI-1, Col Ⅰ and MMP-9). Cumulatively, the dual action of CGM hydrogel-as a physical barrier and cytokine regulator-highlights its promising potential in clinical application for abdominal adhesion prevention.

Prevention of peritoneal adhesions after gynecological surgery: a systematic review

IMPORTANCE

The formation of adhesions after gynecological surgery not only has detrimental impacts on those affected, including pain, obstruction, and infertility, but also imposes a high economic burden on healthcare systems worldwide.

OBJECTIVE

The aim of this review was to evaluate the adhesion prevention potential of all currently available adhesion barriers for gynecological surgery.

EVIDENCE ACQUISITION

We systematically searched MEDLINE and CENTRAL databases for randomized controlled trials (RCTs) on the use of adhesion barriers as compared with peritoneal irrigation or no treatment in gynecological surgery. Only RCTs with second-look surgery to evaluate adhesions in the pelvic/abdominal (but not intrauterine) cavity were included.

RESULTS

We included 45 RCTs with a total of 4,120 patients examining a total of 10 unique types of barriers in second-look gynecological surgery. While RCTs on oxidized regenerated cellulose (significant improvement in 6 of 14 trials), polyethylene glycol with/without other agents (4/10), hyaluronic acid and hyaluronate + carboxymethylcellulose (7/10), icodextrin (1/3), dextran (0/3), fibrin-containing agents (1/2), expanded polytetrafluoroethylene (1/1), N,O-carboxymethylchitosan (0/1), and modified starch (1/1) overall showed inconsistent findings, results for expanded polytetrafluoroethylene, hyaluronic acid, and modified starch yielded the greatest improvements regarding adhesion reduction at 75%, 0-67%, and 85%, respectively.

CONCLUSIONS AND RELEVANCE

Best results for adhesion prevention were reported after applying Gore-Tex Surgical Membrane, hyaluronic acid, and 4DryField®. As Gore-Tex Surgical Membrane is nonabsorbable, it is associated with a greater risk of new adhesion formation due to second-look surgery to remove the product. 4DryField® yielded the greatest improvement in adhesion score compared to all other barrier agents (85%). For better comparability, future studies should use standardized scores and put more emphasis on patient-reported outcome measures, such as pain and infertility.

Comparison of adhesion prevention capabilities of the modified starch powder-based medical devices 4DryField® PH, HaemoCer™ PLUS and StarSil® in the Optimized Peritoneal Adhesion Model

Background and Objectives: The rat Optimized Peritoneal Adhesion Model (OPAM) was developed to provoke adhesion formation with high reproducibility in incidence and extent. In a recent study, the starch-based hemostats 4DryField PH and Arista AH were tested for their capabilities to prevent adhesion formation, the former one certified for adhesion prevention and hemostasis, the latter one only certified for hemostasis. As two further starch-based hemostats, i.e., HaemoCer PLUS and StarSil, have officially been certified for adhesion prevention in the meantime, the present study was conducted to examine their efficacy. Materials and Methods: For this purpose, all three products were applied as a powder that was mixed in situ with saline solution to form a barrier gel. Adhesions were scored using the established macroscopically scoring systems by Lauder and Hoffmann, as well as histopathologically using the score by Zühlke. Animals receiving saline solution solely served as controls. Results: As previously published, 4DryField PH reduced peritoneal adhesions significantly. In contrast, HaemoCer PLUS and StarSil did not lead to a statistically significant reduction of adhesion formation. When comparing 4DryField PH, HaemoCer PLUS and StarSil, 4DryField PH was significantly more effective in preventing peritoneal adhesions. The results of the macroscopic investigation were confirmed by histopathological evaluations. Conclusions: Only 4DryField PH but neither HaemoCer PLUS nor StarSil were capable to effectively prevent adhesion formation, corroborating the assumption that starch-based hemostats do not generally have the capability to act as effective adhesion prevention devices.

Effects of composition and pH on the degradation of hyaluronate and carboxymethyl cellulose gels and release of nanocrystalline silver

Adhesions are fibrous tissue connections which are a common complication of surgical procedures and may be prevented by protecting tissue surfaces and reducing inflammation. The combination of biodegradable polymers and nanocrystalline silver can be used to create an anti-inflammatory gel to be applied during surgery. In this study, sodium hyaluronate and sodium carboxymethyl cellulose were added in concentrations from 0.25% to 1% w/v to aqueous nanocrystalline silver solutions to create viscous gels. Gels were loaded into dialysis cassettes and placed in PBS for 3 days. pH was adjusted using potassium phosphate monobasic and sodium hydroxide. Release of silver into the PBS was measured at several time points. Polymer degradation was compared by measuring the viscosity of the gels before and after the experiment. Gels lost up to 84% of initial viscosity over 3 days and released between 24% and 41% of the added silver. Gels with higher initial viscosity did not have a greater degree of degradation, as measured by percent viscosity reduction, but still resulted in a higher final viscosity. Silver release was not significantly impacted by pH or composition, but still varied between experimental groups.

Postoperative Peritoneal Granulomatous Inflammation After the Application of Potato Starch-Based Anti-Adhesive Agent in Laparoscopic Endometriosis Surgery

Background

Endometriosis is a chronic inflammatory oestrogen-dependent disease. It is characterised by elevated inflammatory markers in the peritoneal milieu with subsequent adhesiogenesis. Nowadays, excisional, and ablative surgeries are considered the main treatment of endometriosis, and adhesiolysis is being performed almost routinely during these procedures. Postoperative adhesion formation is a significant concern for many surgeons, especially as endometriosis patients are assumed to be predisposed to adhesiogenesis. In order to minimise adhesiogenesis after endometriosis surgery, the usage of different barrier methods have been discussed in the literature. Recent studies aim to investigate the effect of potato starch preparations on adhesion formation in endometriosis patients.

Objectives

We aim to describe the findings of a second-look laparoscopy on patients who received a starch-based anti-adhesive agent.

Materials and Methods

We present a retrospective case series that included the medical, surgical, and histopathologic data of three patients.

Main outcome measures

Intraperitoneal adhesion formation and peritoneal inflammation.

Results

All three patients had de-novo adhesions during the second-look laparoscopy. Pathological examination revealed noncaseating granulomatosis of the peritoneum in all patients.

Conclusion

The use of potato starch-based agents as a peritoneal adhesion prophylaxis in laparoscopic endometriosis surgery could lead to granulomatous peritoneal inflammation. Correct application by avoiding powder remnants through complete rinsing and transformation to gel seems to be an important factor to avoid this adverse effect.

What is new?

We aim to highlight that potato starch-based anti-adhesive agents similar to the one used in this study could be a cause of adhesiogenesis and peritoneal inflammation.

Experimental evaluation of the use of starch and carboxymethylcellulose in the prevention of intraperitoneal adhesions in hernia surgery with coated meshes

PURPOSE

Laparoscopic hernia repair involves a risk of adhesion between coated mesh and viscera. Plant polysaccharides such as starch and carboxymethylcellulose (SC) make up a product that acts as a barrier and prevents intraperitoneal adhesions. This study aimed to evaluate whether topical SC can also reduce adhesions between mesh and intra-abdominal organs.

METHODS

Forty rats each received placement of two intraperitoneal mesh fragments, one on each side of the abdominal wall. Randomly, 20 animals received SC on the right and other 20 on the left, leaving the contralateral side as a control. Fourteen days after the surgery, the animals underwent an additional laparotomy in which macroscopic analysis was performed.

RESULTS

As for the percentage of the mesh area affected by adhesion, one (2.6%) animal had > 75% adhesion on the experimental side, and 11 animals (28.9%) on the control side. The adhesion intensity score showed firm adhesions in three (7.9%) animals on the experimental side and nine (23.7%) on the control side.

CONCLUSIONS

The use of SC decreased the intensity of adhesions and the surface area of the mesh affected by adhesions. There was no negative interference of the product in the incorporation of the mesh into the abdominal wall.

Significant adhesion reduction and time saving in pediatric heart surgery with 4DryField PH: A retrospective, controlled study

Adhesions formation after surgery for congenital heart defects can complicate follow-up procedures due to bleeding from detached adhesion bands, injury to cardiac structures or large vessels, all of which do prolong operation times. The problem is enhanced by the fact that detached adhesions are predilection sites for new adhesions setting off a downward spiral. 4DryField® PH gel barrier has demonstrated high efficacy in reducing postoperative adhesions in general surgical and gynecological studies. This retrospective controlled study of 22 patients evaluates whether these positive results can be confirmed in pediatric cardiac surgery. Adhesions were scored from photographs of follow-up interventions by an independent cardiac surgeon blinded to group assignment. The publication provides not only score numbers but also original photographs of all sites for better traceability and transparency. In addition, timesaving due to reduced adhesions was evaluated. Results show a significantly reduced adhesion score for the 4DryField® group. Importantly, this resulted in a significantly shorter period between skin incision and start of cardiopulmonary bypass. In addition, timesaving due reduced adhesion formation was evaluated. The use of 4DryField® was safe, although higher doses per kg were used than in adults.

Barrier materials for prevention of surgical adhesions: systematic review

BACKGROUND

Postoperative surgical adhesions constitute a major health burden internationally. A wide range of materials have been evaluated, but despite constructive efforts and the obvious necessity, there remains no specific barrier widely utilized to prevent postoperative adhesion formation. The aim of this study was to highlight and characterize materials used for prevention of postoperative surgical adhesions in both animal and human studies.

METHODS

A systematic review was performed of all original research articles presenting data related to the prevention of postoperative adhesions using a barrier agent. All available observational studies and randomized trials using animal models or human participants were included, with no restrictions related to type of surgery. PubMed and Embase databases were searched using key terms from inception to August 2019. Standardized data collection forms were used to extract details for each study and assess desirable characteristics of each barrier and success in animal and/or human studies.

RESULTS

A total of 185 articles were identified for inclusion in the review, with a total of 67 unique adhesion barrier agents (37 natural and 30 synthetic materials). Desirable barrier characteristics of an ideal barrier were identified on review of the literature. Ten barriers achieved the primary outcome of reducing the incidence of postoperative adhesions in animal studies followed with positive outputs in human participants. A further 48 materials had successful results from animal studies, but with no human study performed to date.

DISCUSSION

Multiple barriers showed promise in animal studies, with several progressing to success, and fulfilment of desirable qualities, in human trials. No barrier is currently utilized commonly worldwide, but potential barriers have been identified to reduce the burden of postoperative adhesions and associated sequelae.

Comparison of the effect of two anti-adhesion materials on the formation of postoperative adhesions after myomectomy – an experimental study on rabbit does

This study compares the effect of Hyalobarrier Gel and 4DryField® PH on the formation of postoperative adhesions after myomectomy in an experimental study on rabbit does. Thirty experimental animals were divided into three groups: group A – control, group B – use of 4DryField® PH, and group C – use of the Hyalobarrier Gel. A simulated myomectomy was performed in each group. The animals were euthanised 14 days after the procedure and the antiadhesive effect of the above-mentioned preparations was evaluated according to the criteria. Statistical evaluation clearly showed differences in the antiadhesive effect in the scoring systems for groups B and C compared to control group A at a high level of significance. We demonstrated an obvious, statistically confirmed antiadhesive effect of the Hyalobarrier Gel and 4DryField® PH in an experimental model of the rabbit uterus. Comparing both preparations, the Hyalobarrier Gel shows a higher level of effectiveness. Based on the results of the experiment, both preparations can be unambiguously recommended for routine practice.

Reduction of adhesion formation after gynaecological adhesiolysis surgery with 4DryField PH - a retrospective, controlled study with second look laparoscopies

Adhesions are a common consequence of abdomino-pelvic surgery. Efficacy of available adhesion prevention agents is discussed controversially. Here, we used the adhesion barrier 4DryField PH: a powder, which is transformed into a barrier gel with saline solution. The study includes 40 consecutive patients with surgeries for adhesiolysis, endometriosis and other gynaecological pathologies and subsequent second look interventions. The intervention group (n = 17) received 4DryField PH gel while control patients (n = 23) did not receive any adhesion prevention. Severity and extent of adhesion formation were scored during both interventions using an established score. Direct comparison between first and second interventions showed that extent and severity of adhesions could be reduced significantly using 4DryField PH gel. In contrast, in the control group, extent was not reduced and severity was even significantly higher. Direct comparison of second look laparoscopies revealed that adhesion extent and severity were significantly lower in the 4DryField PH than in the control group.Impact StatementWhat is already known on this subject? Adhesion formation after gynaecologic surgeries is known to be frequent and highly problematic as it directly induces complications and additionally makes subsequent surgeries more difficult. The effectiveness of established adhesion barriers is not sufficient to tackle these problems adequately.What the results of this study add? This is the first controlled study using the relatively new adhesion barrier 4DryField PH. It yields a significant reduction of extent as well as severity of adhesions, while adhesiolysis surgery alone does not solve the problem.What the implications are of these findings for clinical practice and/or further research? Usage of 4DryField PH gel seems to be a good approach to solve the adhesion problem of gynaecologic surgery in general and the reformation problem of adhesiolysis surgery specifically. The results should be confirmed in a larger prospective randomised controlled trial.

Changed inflammatory markers after application of 4DryField PH for adhesion prevention in gynecological surgery

Introduction

The development of peritoneal adhesions and the effects of different antiadhesion agents on such mechanisms are not fully understood. Temporary rises of the C-reactive protein (CRP) level have been reported after antiadhesion agent application. We present the changes of inflammation markers observed after use of a starch-based polysaccharide certified for adhesion prevention and hemostasis 4DF (4DryField^® PH).

Method

Retrospective comparative analysis of inflammation markers in 40 patients undergoing laparoscopic adhesiolysis with or without adhesion prophylaxis was conducted. Statistical comparisons were performed by means of paired or unpaired t tests (for normally distributed continuous data), Wilcoxon matched pairs signed-rank tests or Mann–Whitney tests (for not-normally distributed continuous data), Mantel–Cox tests (for continuous data describing time intervals), and Fisher’s exact tests (for discrete data).

Results

The maximum post-operative CRP level was significantly elevated in the 4DF group (87 vs. 29%; p < 0.001), whereas leukocyte concentration and body temperature did not differ between groups. No signs of infection were detected in any of the patients and CRP levels spontaneously dropped to normal values within few days. No side effects or complications were observed in both groups. In second-look surgeries performed for other diagnoses 1–56 weeks after the first interventions, no remnants of 4DF or any peritoneal inflammatory reactions were observed.

Conclusion

The starch-based polysaccharide 4DF can be considered safe and does not induce inflammatory reactions of clinical significance. Further studies regarding 4DF degradation are recommended and, apart from macrophage migration, could also examine corresponding markers such as IL-6 and PCT.

Adhesion prevention after endometriosis surgery - results of a randomized, controlled clinical trial with second-look laparoscopy

Purpose

Adhesion formation after endometriosis surgery is a severe problem affecting up to 90% of patients. Possible complications include chronic pain, ileus, and secondary infertility. Therefore, effective adhesion prophylaxis is desirable, for which the adhesion barrier 4DryField^® PH is evaluated in the present clinical study. It is a starch-based powder that forms a gel after irrigation with saline solution and thus separates surgical sites as physical barrier for adhesion prevention.

Methods

Fifty patients with extensive and deep infiltrating endometriosis were included in this prospective, randomized, controlled clinical trial with two-staged laparoscopic approach. The patients were randomized into two groups, one receiving 4DryField^® PH and the other irrigation with saline solution for adhesion prevention. Adhesion formation was directly scored during second-look interventions considering incidence, extent, and severity. Adhesion prevention treatment in the second surgery was performed corresponding to the first intervention to evaluate the long-term outcome in the later course.

Results

Both groups were comparable with respect to relevant patient parameters. Severity and extent of adhesions were significantly reduced by 85% in the 4DryField^® PH group compared to the control group (mean total adhesion score 2.2 vs. 14.2; p = 0.004). Incidence of adhesion formation based on the number of affected sites was significantly reduced by 53% in the intervention vs. control group (mean 1.1 vs. 2.3 sites; p = 0.004). Follow-up of secondary endpoints is not yet completed; results will become available at a later stage.

Conclusion

Adhesion formation could be reduced significantly by 85% by application of the adhesion barrier 4DryField^® PH.

Trial registration

Trial registration main ID: DRKS00014720, secondary ID: U1111-1213-4142; date of registration 09th May 2018.

Peritoneal Adhesions and their Prevention - Current Trends

The development of adhesions after gynecologic surgery is a severe problem with ramifications that go beyond the medical complications patients suffer (which most often include pain, obstruction and infertility), since they also impose a huge financial burden on the health care system and increase the workload of surgeons and all personnel involved in surgical follow-up care. Surgical techniques to avoid adhesion formation have not proven to be sufficient and pharmaceutical approaches for their prevention are even less effective, which means that the use of adhesion prevention devices is essential for achieving decent prophylaxis. This review explores the wide range of adhesion prevention products currently available on the market. Particular emphasis is put on prospective randomized controlled clinical trials that include second-look interventions, as these offer the most solid evidence of efficacy. We focused on adhesion scores, which are the most common way to quantify adhesion formation. This enables a direct comparison of the efficacies of different devices. While the greatest amount of data are available for oxidized regenerated cellulose, the outcomes with this adhesion barrier are mediocre and several studies have shown little efficacy. The best results have been achieved using adhesion barriers based on either modified starch, i.e., 4DryField® PH (PlantTec Medical GmbH, Lüneburg, Germany), or expanded polytetrafluoroethylene, i.e., GoreTex (W.L. Gore & Associates, Inc., Medical Products Division, Flagstaff, AZ), albeit the latter, as a non-resorbable barrier, has a huge disadvantage of having to be surgically removed again. Therefore, 4DryField® PH currently appears to be a promising approach and further studies are recommended.

Advancement of Biomaterial-Based Postoperative Adhesion Barriers

Postoperative peritoneal adhesion (PPA) is a prevalent incidence that generally happens during the healing process of traumatized tissues. It causes multiple severe complications such as intestinal obstruction, chronic abdominal pain, and female infertility. To prevent PPA, several antiadhesion materials and drug delivery systems composed of biomaterials are used clinically, and clinical antiadhesive is one of the important applications nowadays. In addition to several commercially available materials, like film, spray, injectable hydrogel, powder, or solution type have been energetically studied based on natural and synthetic biomaterials such as alginate, hyaluronan, cellulose, starch, chondroitin sulfate, polyethylene glycol, polylactic acid, etc. Moreover, many kinds of animal adhesion models, such as cecum abrasion models and unitary horn models, are developed to evaluate new materials' efficacy. A new animal adhesion model based on hepatectomy and conventional animal adhesion models is recently developed and a new adhesion barrier by this new model is also developed. In summary, many kinds of materials and animal models are studied; thus, it is quite important to overview this field's current progress. Here, PPA is reviewed in terms of the species of biomaterials and animal models and several problems to be solved to develop better antiadhesion materials in the future are discussed.

Topical Application of High-Dose Mesna Prevents Adhesion Formation: An Experimental Animal Study

BACKGROUND

Adhesion formation is a common complication of abdominal surgeries. Mesna is a drug with fibrinolytic properties which has been used in surgical field to facilitate tissue dissection. The aim of this experimental animal study was to investigate the effect of mesna on prevention of intra-abdominal adhesion in rats.

MATERIALS AND METHODS

Twenty-eight Wistar albino rats were used in the study. To create abdominal adhesion, cecum was abraded in all rats. No additional surgical procedure was performed other than adhesion in group 1 (only adhesion). In the other groups, rats were treated topically by administering 0.9% saline (group 2), 40 mg/kg mesna (group 3), and 400 mg/kg mesna (group 4). All rats were sacrificed on postoperative 21st day. Histopathological and macroscopic evaluations of adhesion formation were performed.

RESULTS

Quantity of adhesion scores (P = 0.022), severity of adhesion scores (P = 0.041), total adhesion scores (P = 0.023), and histopathological adhesion grading scores (P < 0.001) were reduced by 400 mg/kg mesna.

CONCLUSIONS

This is the first study for mesna on prevention of abdominal adhesion formation in rats. We concluded that dose-dependent reduction of adhesion was achieved by mesna. With future studies, topical administration of mesna during open abdominal surgeries may be used to prevent adhesion formation.

Danhong Injection Alleviates Postoperative Intra-abdominal Adhesion in a Rat Model

Background

Among all the common complications that occur after abdominal surgery, intestinal adhesion is perhaps the most unpleasant one. However, current methods to treat and prevent intestinal adhesion are limited; thus, exploring new methods to prevent and treat intestinal adhesion is greatly needed. In this study, we demonstrated that Danhong injection (DHI) may be used as a promising method to prevent and treat intra-abdominal adhesion in a rat model.

Materials and Methods

Forty-eight rats were randomly divided into six groups. Except for the sham-operated group, all rats underwent cecal abrasion to establish an adhesion model. After the operation, the rats in the DHI-treated groups received different doses of DHI via the tail vein daily, while the other group was treated with the same volume of saline solution. Seven days after the operation, all rats were sacrificed, and the degree of adhesion was evaluated by Nair's scoring system. The extent of inflammation in the adhesion tissue was detected by HE staining and the expression of tumor necrosis factor-α (TNF-α) and transforming growth factor-β (TGF-β). The collagen deposition was assessed by Sirius red staining and α-SMA, MMP9, t-PA, and PAI-1 levels. Oxidative stress was indicated by the level of reactive oxygen species (ROS) in adhesion tissues and by immunohistochemical labeling of Nrf2. Furthermore, rat primary peritoneal mesothelial cells (RPMCs) were treated with H₂O₂ and DHI, and NF-κB phosphorylation was detected to illustrate the effect of DHI on oxidative stress.

Results

The intra-abdominal adhesion scores were significantly decreased in the groups treated with a high dose of DHI compared with the control groups, and the degree of inflammation, fibrosis, and oxidative stress was also significantly decreased. DHI treatment significantly reduced the levels of TNF-α, TGF-β1, and PAI and increased the expression levels of MMP9, Nrf2, and t-PA in the adhesion tissues. ROS levels and NF-κB phosphorylation were significantly reduced in DHI-treated RPMCs compared with the control RPMCs.

Conclusion

DHI alleviates the formation of postoperative intra-abdominal adhesions by inhibiting inflammation, collagen deposition, and oxidative stress in a rat model and may serve as a promising drug to prevent intra-abdominal adhesions.

Lymphostasis and Hemostasis in Body-Contouring Surgery Using a Polysaccharide Based Hemostat (4DryField PH)

Background:

Following liposuction, abdominoplasty is the most frequent body-contouring intervention in the world. The transection of small blood vessels in large areas and subsequent bleeding is a viable risk during this procedure. The resulting microvascular bleedings should be stopped thoroughly to reduce the probability of related complications. In this prospective, monocentric, randomized study, the efficacy of the polysaccharide-based hemostat 4DryField PH (4DF) (PlanTec Medical, Lueneburg, Germany) is examined in classic abdominoplasty and lower body lift after Lockwood.

Methods:

For this prospective, monocentric, randomized study, 40 patients underwent surgery for both interventions. Twenty patients received an abdominoplasty, and 20 patients underwent a body lift. In each group, 10 patients have been treated with 4DF, whereas 10 have been served as the untreated control group.

Results:

4DF had neither a beneficial nor a negative effect on necessity of drainages, drainage volume and duration, length of hospital stay or frequency of postoperative seromas, wound healing disturbances, and infections, independent of surgical intervention. Patients in the 4DF group, however, had more individual risk factors, and required extended surgical interventions that might mask primary outcome results.

Conclusions:

This is the first prospective, monocentric, randomized study on 4DF in body-contouring surgery. The use of 4DF did not lead to a better postoperative outcome regarding hemostasis and lymphostasis. Potential benefits need further evaluation in high-volume studies.

Comparison of adhesion prevention capabilities of the modified starch powder-based medical devices 4DryField® PH and Arista™ AH in the Optimized Peritoneal Adhesion Model

Adhesion barriers can be based on numerous substances. In the rat Optimized Peritoneal Adhesion Model (OPAM) the starch-based hemostats 4DryField and Arista were tested for their capability to act in a preventive manner against adhesion formation (applied as a powder that was mixed in situ with saline solution to form a barrier gel). Adhesions were scored using the established scoring systems by Lauder and Hoffmann, as well as histopathologically using the score by Zühlke. Animals receiving saline solution were used as controls. As previously published, 4DryField reduced peritoneal adhesions significantly. However, Arista did not lead to a statistically significant reduction of adhesion formation. When comparing 4DryField and Arista applied in the same manner, only 4DryField was significantly effective in preventing peritoneal adhesions. Histopathological evaluations confirmed the results of the macroscopic investigation, leading to the conclusion that starch-based hemostats do not generally have the capability to function as effective adhesion prevention devices.

Crystalloid fluid suspension results in decreased adhesion burden when compared to bioresorbable membranes in a rat model

INTRODUCTION

Adhesion formation represents a major cause of long-term morbidity. Suspension of intra-abdominal contents in fluid medium may effectively prevent adhesion formation. We compare saline hydro-flotation (NS) to hyaluronate bioresorbable membranes (HBM) for adhesion prevention following surgery.

METHODS

Animals were randomized to four groups: sham (no injury, n = 5), control (injury without intervention, n = 5), HBM (n = 20) or 10 cc NS (n = 21). Interventions were administered after standardized surgical trauma to the cecum and abdominal wall. Necropsies at two weeks were completed to compare adhesion burden using a customary scoring algorithm.

RESULTS

Significant adhesion burden was noted in all rats. HBM sustained a more significant adhesion burden with higher total adhesion scores (HBM = 10 vs NS = 8.1/15, p = 0.02). Gross adhesion scores were lower with NS (5.6/9) compared to HBM (7.1/9, p = 0.01). Neo-vascularity was more common in HBM at 2.6/3 versus 1.9/3 with NS (p = 0.01). Percent of the cecum encased with adhesion was higher with HBM (42%) compared to NS (31%, p = 0.05).

DISCUSSION

Fluid based anti-adhesion methods should be considered for abdominal adhesion formation prevention.

The sticky business of adhesion prevention in minimally invasive gynecologic surgery

PURPOSE OF REVIEW

The negative impact of postoperative adhesions has long been recognized, but available options for prevention remain limited. Minimally invasive surgery is associated with decreased adhesion formation due to meticulous dissection with gentile tissue handling, improved hemostasis, and limiting exposure to reactive foreign material; however, there is conflicting evidence on the clinical significance of adhesion-related disease when compared to open surgery. Laparoscopic surgery does not guarantee the prevention of adhesions because longer operative times and high insufflation pressure can promote adhesion formation. Adhesion barriers have been available since the 1980s, but uptake among surgeons remains low and there is no clear evidence that they reduce clinically significant outcomes such as chronic pain or infertility. In this article, we review the ongoing magnitude of adhesion-related complications in gynecologic surgery, currently available interventions and new research toward more effective adhesion prevention.

RECENT FINDINGS

Recent literature provides updated epidemiologic data and estimates of healthcare costs associated with adhesion-related complications. There have been important advances in our understanding of normal peritoneal healing and the pathophysiology of adhesions. Adhesion barriers continue to be tested for safety and effectiveness and new agents have shown promise in clinical studies. Finally, there are many experimental studies of new materials and pharmacologic and biologic prevention agents.

SUMMARY

There is great interest in new adhesion prevention technologies, but new agents are unlikely to be available for clinical use for many years. High-quality effectiveness and outcomes-related research is still needed.

Human-Derived Amniotic Membrane Is Associated With Decreased Postoperative Intraperitoneal Adhesions in a Rat Model

BACKGROUND

Complications from adhesions after intra-abdominal surgery accounts for ~6% of hospital admissions. Currently, hyaluronate/carboxymethylcellulose represents the main option to prevent postoperative adhesion formation. Human amniotic membrane contains inherent anti-inflammatory properties that mitigate adhesion formation.

OBJECTIVE

This study aimed to evaluate adhesion generation after surgical trauma with amniotic membranes compared with standard intraperitoneal adhesion barriers.

DESIGN

This study is a double-blinded, prospective evaluation.

SETTING

This study was conducted at an animal research facility.

ANIMALS

Forty male rats were studied.

INTERVENTION

Laparotomy was performed with peritoneal disruption to the cecum. Animals were randomly assigned to 1 of 5 groups: sham, control, saline, hyaluronic acid membrane, or amniotic membrane. Animals were euthanized at 14 days.

MAIN OUTCOME MEASURES

Independent gross and histological assessments of adhesions were analyzed between groups by using adhesion scoring and microscopy. Scoring was based on the percentage of the cecum involved (0-4), vascularity of adhesions (0-3), strength (0-3), inflammation (0-3), and fibrosis (0-3). Adhered tissue was harvested for polymerase chain reaction analysis for gene regulation activity.

RESULTS

All rats survived 14 days. Adhesions were observed in all animals. There were significantly fewer adhesions in the amniotic membrane group (2) versus hyaluronic acid (3) group (p = 0.01). The percentage of adhesion to the cecum was lower in the amniotic membrane group (29%) than in the hyaluronic acid group (47%, p = 0.04). Histological examination showed no significant difference between or within the 3 groups for inflammation or fibrosis. Genetic analysis of adhered tissues supported high rates of epithelialization and inhibition of fibrosis in the amniotic membrane group.

LIMITATIONS

We are limited by the small sample size and the preclinical nature of the study.

CONCLUSION

Human-derived amniotic membrane is effective at reducing intraperitoneal adhesion after surgical trauma and is superior to the current antiadhesion barriers. Amniotic membranes are well absorbed and demonstrate short-term safety. See Video Abstract at http://links.lww.com/DCR/A554.

Porous Polylactide Film Plus Atorvastatin-Loaded Thermogel as an Efficient Device for Peritoneal Adhesion Prevention

Peritoneal adhesion is a common postoperative complication that causes many kinds of organ dysfunctions. It can be minimized by the integration of physical isolation and pharmaceutical treatment. However, the gas permeability of traditional medical devices for adhesion prevention is not satisfactory, which increases the risk of infection and inflammation, thus facilitating the formation of peritoneal adhesion. In this study, a device of porous polylactide (PLA) film plus atorvastatin (ATV)-loaded thermogel was developed for peritoneal adhesion prevention. PLA film acted as a physical barrier to prevent the connection of fibrin bridges between the injured tissues and nearby normal organs. Simultaneously, ATV was released to achieve the antifibrin deposition and anti-inflammatory effect. The porous properties of PLA film and thermogel increased the gas permeability and further inhibited the inflammatory responses. The in vivo study demonstrated that the porous PLA film with ATV-loaded thermogel possessed excellent anti-inflammation ability and satisfactory antiadhesion capacity, indicating its great potential for clinical application.

Effect of 4DryField® PH, a Novel Adhesion Barrier, on Recurrence of Intestinal Adhesions after Extensive Visceral Adhesiolysis

Background

Adhesions occur after up to 97% of abdominal interventions causing chronic pain, infertility, and intestinal obstruction. Various concepts to prevent adhesions have been presented but mostly either have low efficacy or are not applicable in resective intestinal surgery or incomplete hemostasis. In this retrospective one-center clinical trial, the course of patients with extensive abdominal adhesiolysis and application of a recent starch-based formulation, 4DryField PH (4DF), is analyzed.

Case Report

Five female patients (age 65–83 years) underwent extensive open adhesiolysis with application of 4DF gel for adhesion prevention, premixed extracorporeally with saline or Ringer's solution (60–70 mL per 5 g 4DF) for homogeneous gel distribution on intestinal loops and in the peritoneal cavity. In addition, dry 4DF powder was dispersed on the greater omentum and subsequently transformed into a gel by dripping with saline or Ringer's solution directly before abdominal closure. Patients were followed up for more than two years, except for one patient who died after nine months due to metastases. One patient with complex situation due to Gore-Tex mesh in the lower abdomen showed no adhesions at scheduled second-look operation but after six months had relaparotomy for adhesiolysis. All other patients have remained free of adhesions or adhesion-related symptoms during follow-up.

Conclusion

Considering the extent and complexity of adhesions, treatment with 4DF gel for adhesion prevention after open adhesiolysis appears promising. Prospective randomized trials should further elaborate on this clinical concept.

Polymer materials for prevention of postoperative adhesion

Postoperative adhesion (POA) is a common complication that often occurs after a variety of surgeries, such as plastic surgery, repair operations of abdominal, pelvic, and tendon, and so forth. Moreover, POA leads to chronic abdominal pain, secondary infertility in women, intestinal obstruction, and other severe complications, which significantly reduce the life quality of patients. In order to prevent the formation of POA, a number of strategies have been developed, among which an emerging method is physical barriers consisting of polymer materials. This review highlights the most commonly used natural and synthetic polymer materials in anti-adhesion physical barriers. The specific features of polymer materials are analyzed and compared, and the possible prospect is also predicted.

STATEMENT OF SIGNIFICANCE

Postoperative adhesion (POA) is a serious complication accompanied with various surgeries. Polymer material-based physical barriers have attracted a large amount of attention in POA prevention. The polymer barriers can effectively avoid the formation of fibrous tissues among normal organs by reducing the interconnection of injured tissues. In this review, specific features of the natural and synthetic polymer materials for application in POA prevention were presented, and the possible prospects were predicted. All in all, our work can provide inspiration for researchers to choose proper polymer materials for preclinical and even clinical anti-adhesion studies.

Decision Making in Bowel Obstruction: A Review

Over the last century there have not been significant changes in the anatomical location of obstruction. The age of presentation has increased along with age related co-morbidity. Management has consequently been challenging as risks keep on increasing with advanced age. Hence, clear decision making has become essential in its management. A selective review of the literature pertaining to common age related aetiologies, diagnosis methods leading to standard decision making and treatment of acute intestinal obstruction was done. The same is obtained from randomized controlled studies, meta-analysis and other related evidence based publications. Predicting the conservative or operative management of Bowel Obstruction (BO) is difficult. BO in young age, in unscarred abdomen and Large Bowel Obstruction (LBO) needs early surgery. Decision on surgery should be taken in paediatric patient by second day and preferably between 3-5 days of admission in adults. Higher American Society of Anaesthesiologists (ASA) grade correlates well with the mortalities. In this article, the timing of surgery, methods to avoid bowel resection and type of surgery in various causes are stressfully analysed and discussed.

Treatment of de-peritonealized intestine with 4DryField® PH prevents adhesions between non-resorbable intra-peritoneal hernia mesh and bowel

BACKGROUND

Intraperitoneal onlay meshes (IPOM) can be associated with intestine-to-mesh adhesion formation, implementing risks like pain, enterocutaneous fistula, infection, and female infertility. This study investigates, whether a treatment of impaired intestinum with the anti-adhesive and hemostyptic agent 4DryField^® PH prevents adhesion formation.

METHODS

In 20 male LEWIS rats uncoated polypropylene meshes were sewn to the inner abdominal wall and the cecum of the respective animal was de-peritonealized by peritoneal abrasion by a gauze swap, and meso-sutures ensured a constant contact of injured areas. Rats were treated with 4DryField^® PH gel either premixed or applied as a powder with in-situ transformation (100 mg powder plus 0.4 ml 0.9% saline solution). One week postoperatively, the extent of intestine-to-mesh adhesions and the quality of mesh ingrowth were evaluated macroscopically by two independent investigators using two scoring systems. Furthermore, specimens were analysed microscopically. All data were compared with control animals without 4DryField^® PH treatment and analysed statistically using student's t-test.

RESULTS

Treatment of de-peritonealised cecum with 4DryField^® PH significantly reduced intestine-to-mesh adhesions in both treatment groups as compared to controls without 4DryField^® PH treatment (68% reduction with premixed gel, P<0.0001; 80% reduction with in-situ gel, P<0.0001). There was no impact on the quality of mesh ingrowth, confirmed histologically by a single-layer mesothelial coverage.

CONCLUSION

These experiments mimick clinical IPOM implantation scenarios with adjacent bowel depleted from peritoneum. 4DryField^® PH gel treatment resulted in intestinal mesothelial surface recovering without development of bowel-to-mesh adhesions. Concurrently, integration of mesh into the abdominal wall is undisturbed by 4DryField^® PH treatment.