Efficacy of a hyaluronan derivative gel in postsurgical adhesion prevention in the presence of inadequate hemostasis

A resorbable hyaluronic acid hydrogel to prevent adhesion in porcine model under laparotomy pelvic surgery

Surgical post-operative adhesions can lead to serious clinical complications. Barrier agent is the broad usage for the prevention of post-operative adhesions. This study aimed to evaluate the reducing adhesion efficacy of non-animal hyaluronic acid (HA) hydrogel in pigs undergoing conventional laparotomy pelvic surgery. HA hydrogel was applied to eighteen female pigs who underwent conventional laparotomy. The adhesion degrees and histopathology were evaluated in bilateral uterine horns as well as peritoneal sidewall excision. In the present study, all animals survived and had no complications after the surgery. The histopathological observations were demonstrated that HA obviously improved laparotomy pelvic surgery-induced adhesion in peritoneal sidewall and uterine horn. The anastomotic healing score of injury + HA group was significantly lower than the injury alone group. We conclude HA hydrogel can attenuate the post-operative adhesions in porcine.

Anti-adhesion Gel versus No gel following Operative Hysteroscopy prior to Subsequent fertility Treatment or timed InterCourse (AGNOHSTIC), a randomised controlled trial: protocol

STUDY QUESTIONS

Does the application of anti-adhesion gel, compared to no gel, following operative hysteroscopy to treat intrauterine pathology in women wishing to conceive increase the chance of conception leading to live birth?

WHAT IS KNOWN ALREADY

Intrauterine adhesions (IUAs) following operative hysteroscopy may impair reproductive success in women of reproductive age. Anti-adhesion barrier gels may decrease the occurrence of IUAs, but the evidence on their effectiveness to improve reproductive outcomes is sparse and of low quality.

STUDY DESIGN SIZE DURATION

This multicentre, parallel group, superiority, blinded and pragmatic randomised controlled trial is being carried out in seven participating centres in Belgium. Recruitment started in April 2019. Women will be randomly allocated to treatment with anti-adhesion gel (intervention group) or no gel (control group). Sterile ultrasound gel will be applied into the vagina as a mock-procedure in both treatment arms. The patient, fertility physician and gynaecologist performing the second-look hysteroscopy are unaware of the allocated treatment. Power analysis, based on a target improvement of 15% in conception leading to live birth using anti-adhesion gel, a power of 85%, a significance level of 5%, and a drop-out rate of 10%, yielded a number of 444 patients to be randomised. The baseline rate of conception leading to live birth in the control group is expected to be 45%.

PARTICIPANTS/MATERIALS SETTING METHODS

Women of reproductive age (18-47 years), wishing to conceive (spontaneously or by fertility treatment) and scheduled for operative hysteroscopy to treat intrauterine pathology (endometrial polyps, myomas with uterine cavity deformation, uterine septa, IUAs or retained products of conception) are eligible for recruitment. Women may try to conceive from 3 to 6 weeks after receiving allocated treatment with follow-up ending at 30 weeks after treatment. If the woman fails to conceive within this timeframe, a second-look hysteroscopy will be scheduled within 2-6 weeks to check for IUAs. The primary endpoint is conception leading to live birth, measured at 30 weeks after randomisation. The secondary endpoints are time to conception, clinical pregnancy, miscarriage and ectopic pregnancy rates, measured at 30 weeks after receiving allocated treatment. The long-term follow-up starts when the patient is pregnant and she will be contacted every trimester.

STUDY FUNDING/COMPETING INTERESTS

This work is funded by the Belgian Healthcare Knowledge Centre (KCE). The anti-adhesion gel is supplied at no cost by Nordic Pharma and without conditions. Dr. Tomassetti reports grants and non-financial support from Merck SA, non-financial support from Ferring SA, personal fees and non-financial support from Gedeon-Richter, outside the submitted work. None of the other authors have a conflict of interest.

Efficacy of Applying Hyaluronic Acid Gels in the Primary Prevention of Intrauterine Adhesion after Hysteroscopic Myomectomy: A Meta-Analysis of Randomized Controlled Trials

Intrauterine adhesion (IUA), which mainly occurs after intrauterine surgery or an inflammatory process, is an important but often neglected condition in women of reproductive age. The presentation of IUA varies greatly, ranging from symptom-free to severe, with amenorrhea or infertility. With much advanced development of intrauterine instruments, more intrauterine diseases can be successfully cured by hysteroscopic surgery. Among these, submucosal myoma is one of the best examples. Submucosal myomas are often related to abnormal bleeding, anemia, and possible infertility or miscarriage. However, submucosal myoma after hysteroscopic myomectomy may be complicated by IUA in various grades of severity, and its incidence and prevalence might be nearly one-quarter to one-third of patients, suggesting an urgent need for efforts to decrease the risk of developing IUA after hysteroscopic myomectomy. Many strategies have been reported to be useful for this purpose, and intrauterine application of anti-adhesive gels, such as polyethylene oxide–sodium carboxymethylcellulose (PEO-NaCMC) or auto-crosslinked hyaluronic acid (ACHA), has become increasingly popular in routine clinical practice. This meta-analysis is aimed at investigating the effect of ACHA on the primary prevention of IUA formation after hysteroscopic myomectomy. A pooled analysis of three studies (hysteroscopic surgeries for fibroids, polyps, and septum) including 242 women showed that using PEO-NaCMC or ACHA gel decreased the IUA rate with an odds ratio (OR) of 0.364 (95% confidence interval (CI) 0.189–0.703, p = 0.03). Pooled analysis of two studies that limited the use of ACHA in 119 women showed that the application of ACHA gel for the primary prevention of IUA in patients after hysteroscopic myomectomy led to a statistically significant reduction of the development of IUA postoperatively (OR 0.285, 95% CI 0.116–0.701, p = 0.006). All of this suggests that the use of ACHA gel in patients after hysteroscopic myomectomy could significantly reduce de novo IUA, although more evidence is needed.

Comparison of Autocross-Linked Hyaluronic Acid Gel and Intrauterine Device for Preventing Intrauterine Adhesions in Infertile Patients: A Randomized Clinical Trial

Objectives:

The objective of this study is to evaluate the efficacy of autocross-linked hyaluronic acid (HA) compared with intrauterine device (IUD) for preventing intrauterine adhesions (IUAs) in infertile patients after hysteroscopic adhesiolysis.

Materials and Methods:

A randomized clinical trial (ChiCTR-IOR-16007746). Upon completion of adhesiolysis, 3 ml of HA gel was placed into the uterine cavity in Group A; 3 ml of HA gel and an IUD were placed in Group B; and only an IUD was placed in Group C. A second hysteroscopic examination was performed in all patients at approximately 1 month postoperatively for the evaluation of IUA. The primary outcome measure was the effective rate of IUA prevention based on the American Fertility Society (AFS) scoring system.

Results:

Eighty-nine women were randomly distributed into two groups for intention to treat with 30 patients in Group A, 24 patients in Group B, and 35 patients in Group C. Patients were scored and stratified into three degrees and were enrolled using the simple random sampling method. The three groups were well balanced. There were no significant differences in age, endometrial thickness, the previous number of pregnancy, and the distribution of adhesion categories across mild, moderate, and severe between the three groups. The effective rate of IUA prevention, the AFS score after therapy, and the percentage improvements of Chinese score and AFS score before and after surgery were statistically significant difference between Groups A and C. The clinical pregnancy rate in Group A was higher than those in Groups B and C, but the difference was not statistically significant.

Conclusion:

HA gel has an advantage over an IUD in reducing IUA recurrence and decreasing adhesions.

A new bioabsorbable polymer film to prevent peritoneal adhesions validated in a post-surgical animal model

Background

Peritoneal adhesions are a serious surgical postoperative complication. The aim of this study is to investigate, in a rat model, the anti-adhesive effects of a bioabsorbable film of polymer combining polyethylene glycol and polylactic acid.

Materials and methods

Sixty-three animals were randomized into five groups according to the anti-adhesion treatment: Hyalobarrier^®, Seprafilm^®, Polymer A (PA), Polymer B (PB), and control. The rats were euthanized on days 5 and 12 to evaluate the extent, severity and degree of adhesions and histopathological changes. Three animals were euthanized at day 2 in PA, PB and control groups to observe the in vivo elimination.

Results

Macroscopic adhesion formation was significantly lower in the PA group than in the control group at day 5 (median adhesion score 0±0 vs 9.6 ±0.5 p = 0.002) and at day 12 (0±0 vs 7.3±4 p = 0.02). Furthermore, median adhesion score at day 5 was significantly lower in the PA group than in the Seprafilm group (0±0 vs 4.2± 3.9 p = 0.03). Residence time of PA seems longer than PB.

Conclusion

The PA bioabsorbable film seems efficient in preventing the formation of peritoneal adhesions.

Prospective, Randomized, Double Blind, Multicenter Study for an Autocrosslinked Polysaccharide Gel to Evaluate Antiadhesive Effect and Safety Compared to Poloxamer/Sodium Alginate After Thyroidectomy

The aim of the study was to compare the efficacy and safety between an autocrosslinked polysaccharide (ACP) gel (Hyalobarrier) and a poloxamer/sodium alginate (P/SA: Guardix-SG) in preventing adhesions after thyroidectomy and demonstrate the noninferiority of ACP gel to P/SA. To identify differences of antiadhesive efficacy and safety between the ACP gel and P/SA, we investigated various variables such as the proportion of normal esophageal motility as assessed using marshmallow esophagography, swallowing impairment, adhesion severity and so on. This prospective, randomized, double-blinded, multicenter, phase III study investigated the antiadhesive efficacy and safety of ACP gel compared with those of P/SA for 12 weeks. Subjects were randomly assigned to receive either ACP gel (n = 97) or P/SA (n = 96). The primary endpoint was the proportion of normal esophageal motility as assessed using marshmallow esophagography, while the secondary endpoints included swallowing impairment, adhesion severity, laryngoscopic assessment of the vocal cords, and voice range profile. Safety endpoints included adverse events. There was no significant difference between the ACP gel and P/SA groups in the proportion of normal esophageal motility as the primary endpoint (P = 0.7428). In addition, there were no differences in the secondary or safety endpoints between the 2 groups. It was demonstrated that ACP gel was not inferior to P/SA. ACP gel appears both effective and safe for use in preventing adhesions after thyroidectomy.

Role of morphologic characteristics of the uterine septum in the prediction and prevention of abnormal healing outcomes after hysteroscopic metroplasty

STUDY QUESTION

Can morphologic measurements (width, length and surface area) of the uterine septum predict healing-dependent abnormal anatomic results [ARs; residual septum (RS) and intrauterine adhesions in other locations (IUA-OLs)] after complete hysteroscopic metroplasty (HM)?

SUMMARY ANSWER

Significant predictors of ARs are the septal width and, to a lesser extent, septal surface area.

WHAT IS KNOWN ALREADY

Anatomic results after hysteroscopic metroplasty have very large variation. A RS >1 cm and IUA-OLs can aggravate reproductive outcomes, resulting in the need for reoperation. New criteria for diagnosing a uterine septum according to the European Society of Human Reproduction and Embryology (ESHRE) and European Society for Gynaecological Endoscopy (ESGE) have been suggested (ESHRE-ESGE criteria). Autocross-linked hyaluronic acid gel (autocross-linked polysaccharide) has an antiadhesive effect.

STUDY DESIGN, SIZE, DURATION

A prospective, observational cohort study was performed with 96 women consecutively enrolled between 2007 and 2012.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women who had uterine septum and previous miscarriage or infertility presented for evaluation at a university hospital, private hospital or private medical center were included. Preoperative septal width, length and surface area were determined with three-dimensional sonohysterography. Women were treated by hysteroscopy in a standardized manner with three- or four-dimensional transrectal ultrasound guidance (complete resection). Patients received either no adhesion barrier (49 patients) or adhesion barrier with autocross-linked polysaccharide (47 patients). Anatomic results were assessed with three-dimensional sonohysterography and second-look hysteroscopy. Healing-dependent ARs were reported using both American Society of Reproductive Medicine (ASRM) criterion of RS length >1 cm (ASRM>1 cm criterion) and ESHRE-ESGE criteria. Univariate and multivariate logistic regression were used to identify predictors of RS, IUA-OLs and ARs.

MAIN RESULTS AND ROLE OF CHANCE

In patients who had no adhesion barrier, ARs were diagnosed in 11 of 49 patients (23%) using the ASRM > 1 cm criterion and in 20 of 49 patients (41%) using the ESHRE-ESGE criteria for RS [odds ratio (OR)ESHRE-ESGE:ASRM, 2.4, P = 0.05]. In the patients who had autocross-linked polysaccharide, ARsASRM > 1 cm were diagnosed in 2 of 47 patients (4%) and ARsESHRE-ESGE in 4 of 47 patients (9%). RSESHRE-ESGE was diagnosed significantly more often than RSASRM > 1 cm 19 of 96 (20%) versus 5 of 96 (5%) in all patients (ORESHRE-ESGE:ASRM > 1 cm = 4.5, P < 0.01). In patients who had no adhesion barrier, logistic regression with ASRM > 1 cm and ESHRE-ESGE criteria showed that the width and surface area were predictors of ARs. Models adjusted by patient group confirmed the significance of width as a predictor of ARsASRM > 1 cm [OR for width, 3.5 (P < 0.01); OR for group, 0.22 (P < 0.01)], width as a predictor of ARsESHRE-ESGE [OR for width, 2.2 (P < 0.01); OR for group, 0.26 (P < 0.01)] and surface area as a predictor of ARsASRM > 1 cm [OR for surface area, 1.5 (P < 0.01)]; OR for group, 0.32 (P < 0.01). In patients who had autocross-linked polysaccharide, these predictors were not significant. Receiver-operating characteristic curves showed cutoff values for ARsASRM > 1 cm (septal width, 3.42 cm; septal surface area, 4.68cm²) and ARsESHRE-ESGE (septal width, 3.42 cm; septal surface area, 3.51cm²).

LIMITATIONS AND REASONS FOR CAUTION

Patients were enrolled in the adhesion barrier group in a time-dependent, consecutive and non-randomized manner.

WIDER IMPLICATIONS OF THE FINDINGS

A wide septum and large surface area may be indications for adhesion barrier. The use of autocross-linked polysaccharide reduces the risk of ARs. The ESHRE-ESGE criteria may cause greater frequency of recognition of RS than the ASRM > 1 cm criterion, which could result in more frequent reoperations with use of the ESHRE-ESGE criteria, possibly without any significant effect on reproductive performance.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Jagiellonian University (grant no. K/ZDS/003821). The authors have no competing interest to declare.

Hyaluronidase-sensitive nanoparticle templates for triggered release of HIV/AIDS microbicide in vitro

This study was designed to test the hypothesis that a triggered release of a topical microbicide (tenofovir) from hyaluronic acid nanoparticles (HA-NPs) can be achieved under the influence of hyaluronidase (HAase) enzyme. A fractional factorial experimental design was used to examine the factors [molar concentrations of adipic acid dihydrazide (X1) and 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (X2), volume of acetone (X3) and reaction time (X4)] influencing the responses, Y1; particle mean diameter: PMD (nanometers: nm), Y2; polydispersity index: PDI and Y3; zeta (ζ) potential: (millivolts). The amide bond formation between HA and ADH after cross-linking was confirmed by FT-IR and (13)C-NMR analyses. These NPs were also characterized for cytotoxicity on a human vaginal epithelial cell line and L. crispatus. When formulated with factors X1; 2.49 mM, X2; 9.96 mM, X3; 60 mL, X4; 6 h, HA-NPs exhibited a spherical shape with PMD, PDI, ζ potential, encapsulation efficiency, and drug loading of 70.6 ± 4.1 nm, 0.07 ± 0.02, -38.2 ± 2.8 mV, 51.8 ± 2.4% w/w and 26.1 ± 1.2% w/w, respectively, (n = 3). Unlike for HA based gel, HAase significantly triggered the drug release and HA degradation from the NPs after 24 h (~90% w/w and 65% w/w, respectively); whereas, in its absence, these values were ~39% w/w and 26% w/w, respectively. The NPs were non-cytotoxic to human vaginal VK2/E6E7, End1/E6E7 cells and Lactobacillus crispatus. These data highlight the potential of HAase-sensitive HA-NPs templates for the controlled and vaginal delivery of anti-HIV/AIDS microbicides.

Rectus abdominus fascial sheath usage for crural reinforcement during surgical management of GERD: preliminary report of a prospective randomized clinical trial

PURPOSE

Many materials are currently being used to reinforce the crural repair. Perforation, intensive fibrosis, and price are limiting the usage of these materials. Our purpose was to seek an alternative, cheap, always available, and inert material to use for cruroplasty reinforcement.

METHODS

Twenty-four patients participated and were randomly divided into 2 groups (graft+laparoscopic Nissen fundoplication and laparoscopic Nissen fundoplication alone) with 12 patients in each group. Total operation time, postoperative dysphagia rate, dysphagia improvement time, postoperative pain, recurrence, and incisional hernia rate were compared.

RESULTS

There was no difference in terms of study parameters between both groups except for the mean operation time.

CONCLUSIONS

Autograft hiatoplasty seems to be a good alternative for crural reinforcement. It provides safe reinforcement, has the same dysphagia rates as meshless hiatoplasty, and avoids potential complications of redo surgery by minimizing extensive fibrosis. Furthermore, the rectus abdominus sheath is always available and inexpensive.

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.

Prevention of postoperative peritoneal adhesions

Adhesions are bands of tissue that connect organs together. It is frequently reported after surgery and remains a major problem for health and society. Efforts to prevent or reduce peritoneal adhesions mostly have been unsuccessful, hindered by their empirical basis, lack of good predictive animal models and complexity of adhesion pathogenesis. Although a good surgical technique is a crucial part of adhesion prevention, the technique alone cannot effectively eliminate the adhesions. Thus, there remains a room for further research. A comprehensive literature review of published experimental and clinical studies of adhesion prevention was carried out at the University of Bristol electronic library (MetaLib) with cross-search of seven different medical databases (AMED-Allied and Complementary Medicine Database, BIOSIS Previews on Web of Knowledge, Cochrane Library, Embase and Medline on Web of Knowledge, OvidSP and PubMed) by using key words (peritoneal adhesions, postoperative adhesions, prevention) to explore the progress in different surgical strategies and adjuvant materials used to prevent adhesions formation and reformation. By the end of the study, recommendations formulated for surgeons to be followed during the operations to prevent, as much as possible, the postoperative adhesions.

Intercoat gel (oxiplex): efficacy, safety, and tissue response in a laparoscopic mouse model

STUDY OBJECTIVE

To study the efficacy and safety of Intercoat gel in a laparoscopic mouse model with pneumoperitoneum-enhanced adhesion formation.

DESIGN

Randomized controlled trial. Evidence obtained from a properly designed, randomized, controlled trial (Canadian Task Force classification I).

SETTING

University laboratory research center.

SUBJECTS

Balb\c female mice 9 to 10 weeks old.

INTERVENTIONS

Two laparoscopic mouse models for adhesion formation were used. In the first model, adhesions following bipolar opposing lesions in the pelvis were enhanced by 60 minutes of carbon-dioxide pneumoperitoneum. In the second model, adhesions were further enhanced by bowel manipulation. The first experiment evaluated the efficacy of Intercoat in both models. The second experiment evaluated the efficacy of Intercoat in the first model, when applied immediately on the lesion, when applied at the end of the pneumoperitoneum, and when applied in the upper abdomen. Biopsy specimens were taken after 7 days and were evaluated after hematoxylin-eosin and CD45 staining.

MEASUREMENTS AND MAIN RESULTS

Qualitative and quantitative adhesion scoring. Morphology was evaluated by standard light microscopy. In both models, Intercoat decreased adhesion formation whether applied immediately on the lesion or at the end of the pneumoperitoneum (qualitative and quantitative scoring p <.0001 and p <.0001, respectively). Intercoat application is associated with tissue redness, vascular congestion, and cellular edema but without an inflammatory reaction. Applied in the upper abdomen, Intercoat does not increase adhesions, but decreases adhesions at higher doses (p =.0024). Intercoat in high doses had a toxic effect (p =.0058).

CONCLUSION

Intercoat is an effective antiadhesion product. It is associated with tissue edema and vasodilatation as observed after 7 days both macroscopically and by histology.

Effect of adhesion barrier (interceed TC7) on two-stage orchidopexy operation

OBJECTIVE

In two-stage orchidopexy, adhesions formed after the first stage usually cause difficulty during the second operation and may even lead to injury to the testis itself or to the spermatic cord. We investigated whether the use of adhesion-preventing barriers in the abdominal or pelvic region during surgery could lessen adhesions formed during two-stage orchidopexy and thus ease dissection.

MATERIAL AND METHODS

The study subjects comprised 21 male, albino, 30-day-old Wistar rats that were divided into three equal groups. In Group 1, the right testes were enveloped in adhesion barriers after dissection and sutured to the inguinal canal. In Group 2, the right testes were sutured to the inguinal canal without the barriers. In Group 3 (sham-operated group), all testes were dissected but no suturing was performed. Rats were sacrificed after 21 days and the ipsilateral testes were harvested.

RESULTS

Dissection of barrier-enveloped testes was relatively easy; however, no significant (p < 0.535) difference was seen in adhesion scores between Groups 1 and 2. Total tissue collagen was estimated by means of the hydroxyproline content. Tissue hydroxyproline levels were 16.04 +/- 8.58, 13.20 +/- 6.34 and 14.71 +/- 5.51 microg/mg wet tissue in Groups 1-3, respectively and these differences were not significant. The histopathologic evaluation revealed significant differences only in the thickness of the tunica albuginea in Groups 1 and 2 (110.0 +/- 30.0 vs 77.1 +/- 21.3 microm, respectively; p < 0.038).

CONCLUSION

The adhesion scores and the biochemical and histopathological examinations showed that an adhesion barrier is not beneficial in two-stage orchidopexy.

Auto-crosslinked hyaluronic acid gel accelerates healing of rabbit flexor tendons in vivo

This study's purpose was to assess the in vivo effect of auto-crosslinked hyaluronic acid (HA) gel, a natural HA derivative with increased viscosity and tissue residence time, on adhesions and healing of injured and surgically repaired rabbit digital flexor tendons. The second and third right deep digital flexor tendons from 48 rabbits (n = 96 tendons) were cut and repaired with a modified Kessler and running peripheral suture. Animals were randomized to two groups, receiving either HA gel or saline injected around both freshly repaired tendons. After 2, 3, 6, and 12 weeks, six rabbits in each group were euthanized. Tendon pull-out force and breaking strength were measured as a value for adhesion formation and tendon healing, respectively. A histological assessment of adhesions and healing was related to the mechanical results. A significantly faster increase in breaking strength was found in HA gel-treated compared to saline-treated tendons; this coincided with a significantly accelerated tissue repair response after injury. No significant difference in adhesion formation was found between the two groups at any time. Our results indicate a significant acceleration of in vivo healing of tendons treated with HA gel. Adhesion formation was unaffected. These results could have important clinical value in promoting rehabilitation after tendon injury.

Efficacy of barriers and hypoxia-inducible factor inhibitors to prevent CO(2) pneumoperitoneum-enhanced adhesions in a laparoscopic mouse model

STUDY OBJECTIVE

To investigate the effects of hypoxia-inducible factor (HIF) inhibitors, flotation agents, barriers, and a surfactant on pneumoperitoneum-enhanced adhesions in a laparoscopic mouse model.

DESIGN

Prospective randomized trial (Canadian Task Force classification I).

SETTING

Department of Obstetrics and Gynecology, University Hospital Gasthuisberg, Catholic University of Leuven.

SUBJECTS

One hundred fourteen female BALB/c mice.

INTERVENTIONS

Adhesions were induced during laparoscopy in BALB/c female mice. Pneumoperitoneum was maintained for 60 minutes with humidified CO(2). In 3 experiments the effects of HIF inhibitors such as 17-allylamino 17-demethoxygeldanamycin, radicicol, rapamycin, and wortmanin, flotation agents such as Hyskon and carboxymethylcellulose, barriers such as Hyalobarrier gel and SprayGel, and surfactant such as phospholipids were evaluated.

MEASUREMENTS AND MAIN RESULTS

Adhesions were scored after 7 days during laparotomy. Adhesion formation decreased with the administration of wortmannin (p <.01), phospholipids (p <.01), Hyalobarrier Gel (p <.01), and SprayGel (p <.01).

CONCLUSIONS

These experiments confirm the efficacy of barriers and phospholipids to separate or lubricate damaged surfaces. They also confirm the role of mesothelial hypoxia in this model by the efficacy of the HIF inhibitor wortmannin.

The influence of blood on the efficacy of intraperitoneally applied phospholipids for prevention of adhesions

BACKGROUND

The formation of adhesions following abdominal surgery is a well known problem. In previous studies we demonstrated the efficacy and safety of intraperitoneally applied phospholipids in order to prevent adhesion formation. This study evaluates the influence of blood on the efficacy of intraperitoneally applied phospholipids for prevention of adhesions.

METHODS

In 40 Chinchilla rabbits adhesions were induced by median laparotomy, standardized abrasion of the visceral and parietal peritoneum in defined areas of the ventral abdominal wall and the caecum. The animals were randomly divided into four groups. They received either phospholipids 3.0% or normal saline (NaCl 0.9%) (5 ml/kg body weight). In 50% of the rabbits we simulated intraperitoneal bleeding by administration of blood (1.5 ml/kg body weight). The other half served as control group. Ten days following the operation the animals were sacrificed and adhesion formation was assessed by computer aided planimetry and histopathologic examination.

RESULTS

The median adhesion surface area in the NaCl-group (n = 9) amounted to 68.72 mm2, in the NaCl+Blood-group (n = 10) 147.68 mm2. In the Phospholipid (PhL)-group (n = 9) the median adhesion surface area measured 9.35 mm2, in the PhL+Blood-group (n = 9) 11.95 mm2. The phospholipid groups had a significantly smaller adhesion surface area (p < 0.05).

CONCLUSION

Again these results confirm the efficacy of phospholipids in the prevention of adhesions in comparison to NaCl (p = 0.04). We also demonstrated the adhesion preventing effect of phospholipids in the presence of intraperitoneal blood.

Prevention of adhesions in gynaecological endoscopy

Adhesions resulting from gynaecological endoscopic procedures are a major clinical, social and economic concern, as they may result in pelvic pain, infertility, bowel obstruction and additional surgery to resolve such adhesion-related complications. Although the minimally invasive endoscopic approach has been shown to be less adhesiogenic than traditional surgery, at least with regard to selected procedures, it does not totally eliminate the problem. Consequently, many attempts have been made to further reduce adhesion formation and reformation following endoscopic procedures, and a wide variety of strategies, including surgical techniques, pharmacological agents and mechanical barriers have been advocated to address this issue. The present review clearly indicates that there is no single modality proven to be unequivocally effective in preventing post-operative adhesion formation either for laparoscopic or for hysteroscopic surgery. Furthermore, the available adhesion-reducing substances are rather expensive. Since excellent surgical technique alone seems insufficient, further research is needed on an adjunctive therapy for the prevention and/or reduction of adhesion formation following gynaecological endoscopic procedures.

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.

In vivo performance of antibiotic embedded electrospun PCL membranes for prevention of abdominal adhesions

The aim of this study was to prepare nonwoven materials from poly(epsilon-caprolactone) (PCL) and their antibiotic containing forms by electrospinning, so as to prevent postsurgery induced abdominal adhesions in rats. epsilon-Caprolactone was first polymerized by ring-opening polymerization, and then it was processed into matrices composed of nanofibers by electrospinning. A model antibiotic (Biteral) was embedded within a group of PCL membranes. In the rat model, defects on the abdominal walls in the peritoneum were made to induce adhesion. The plain or antibiotic embedded PCL membranes were implanted on the right side of the abdominal wall. No membrane implantation was made on the left side of the abdominal wall that served as control. Macroscopical and histological evaluations showed that using these barriers reduces the extent, type, and tenacity of adhesion. The antibiotic embedded membranes significantly eliminated postsurgery abdominal adhesions, and also improved healing.

Clinical evaluation of a hyaluronan-based gel following microsurgical reconstruction of peripheral nerves of the hand

A controlled clinical trial was performed to investigate the safety and efficacy of the hyaluronate-based gel polymer Hyaloglide after microsurgical reconstruction of peripheral nerves of the hand. Thirty patients were randomized to receive either no postsurgical treatment (n = 16) or Hyaloglide (n = 14) and were clinically evaluated at various intervals for 1 year. The application of Hyaloglide posed no safety concerns. Efficacy was assessed by the recovery of sensitivity, measurement of pain, and progression of Tinel's sign. The Hyaloglide-treated group showed better improvement in recovery from pain, approaching statistical significance during the first 3 months postsurgery. Likewise, recovery of sensitivity was also higher in the Hyaloglide-treated group throughout the entire follow-up period, and the distance of Tinel's sign was longer in the Hyaloglide-treated group (P < 0.05 at day 30). The application of Hyaloglide may improve recovery of sensitivity and decrease pain following microsurgical repair of the peripheral nerves of the hand.

Auto-Cross-Linked Hyaluronic Acid Gel Does Not Reduce Intra-Abdominal Adhesions or Abscess Formation in a Rat Model of Peritonitis

BACKGROUND

Prevention of adhesion and abscess formation would decrease mortality and morbidity after peritonitis. In this study the effect of a new anti-adhesive, auto-cross-linked hyaluronic acid polysaccharide (ACP) gel, on adhesion and abscess formation was studied in a rat peritonitis model.

MATERIALS AND METHODS

In experiment 1, bacterial peritonitis was induced in 24 Wistar rats, using a cecal ligation and puncture model. Animals were randomized to receive 4 mL ACP gel (4%) or 4 mL phosphate buffered saline (PBS). After 2 weeks animals were killed and adhesions and abscesses were scored. In experiment 2, 72 rats underwent the same procedure but were randomized to receive 2 mL ACP gel, 4 mL ACP gel, or 4 mL PBS. After 1 and 3 weeks, respectively, half of the animals in each group were killed and adhesions and abscesses were scored.

RESULTS

The median total adhesion score was 12 (range, 3-20) in the ACP group and was 9 (range, 6-12) in the PBS group (not significant) in experiment 1. 91% of rats in the ACP group developed abscesses, versus 90% in the control group. There were no significant differences in abscess size or number of abscesses. In experiment 2, total adhesion scores in the 2 mL ACP group, 4 mL ACP group, and PBS group were 4 (range, 2-20), 6 (range, 1-11), and 6 (range, 1-18), respectively, (not significant) after 1 week and 3.5 (range, 1-8), 5 (range, 2-15), and 4 (range, 0-9), respectively, (not significant) after 3 weeks. All rats in the 2 mL ACP group and the PBS group and 83% of the 4 mL ACP group had developed abscesses after 1 week. After 3 weeks these percentages were 80, 75, and 73, respectively. There were no significant differences in size or number of abscesses between groups both after 1 and 3 weeks.

CONCLUSION

ACP does not reduce adhesion and abscess formation in a rat peritonitis model.

Innovative barriers for peritoneal adhesion prevention: liquid or solid? A rat uterine horn model

OBJECTIVE

To compare the effects of solid barriers (PDLA membrane and foil, Interceed), innovative barrier solutions (Adept and Hyalobarrier Gel, phospholipid emulsion), and Ringer's lactate solution in preventing postsurgical peritoneal adhesions in the rat.

DESIGN

Prospective, randomized experimental study.

SETTING

Rat model in an academic research environment.

ANIMAL(S)

Female, nonpregnant Wistar rats.

INTERVENTION(S)

Standardized surgical injuries were applied to the parietal and visceral peritoneum and the uterine horns. The barrier agents were applied and the wound was closed. A second-look laparoscopy was performed 31 days after surgery to assess adhesion formation.

MAIN OUTCOME MEASURE(S)

Severity and extent of adhesion formation assessed using a multidimensional adhesion scoring system.

RESULT(S)

Significantly fewer postsurgical adhesions were seen after treatment with Adept, Hyalobarrier Gel, Interceed, PDLA membrane, and phospholipid emulsion than after Ringer's lactate solution. Severe, clinically relevant adhesions were not observed after Hyalobarrier Gel and in only one animal after Adept.

CONCLUSION(S)

Both solid and liquid barriers can prevent adhesions. Hydroflotation formulas, such as Adept and Hyalobarrier Gel, avoid suture-induced adhesions, are easy to use, and their protective effects are evenly distributed. They are suitable for adhesion prevention after multifocal trauma in rats, and require further testing in the everyday clinical situation.

Reduction of postoperative adhesions with an auto-crosslinked hyaluronan gel in gynaecological laparoscopic surgery: a blinded, controlled, randomized, multicentre study

BACKGROUND

Following myomectomy, postoperative adhesions occur in many patients with adverse effects on fertility. This study investigated the applicability, safety and efficacy of an auto-crosslinked hyaluronan gel in preventing adhesion formation after laparoscopic myomectomy.

METHODS

Fifty-two patients aged 22-42 years, undergoing surgery at four centres, were randomly allocated to receive either the gel or no adhesion prevention. The incidence and severity of postoperative adhesions were assessed laparoscopically after 12-14 weeks in a blinded, scored fashion. The primary efficacy variable was the presence/absence of postoperative adhesions at second-look.

RESULTS

A nonsignificantly higher proportion of patients receiving the gel were free from adhesions (13 of 21; 62%) compared with control patients (9 of 22; 41%), with a statistically significant difference between the severity of uterine adhesions at baseline and at second-look (0.3 +/- 0.9 versus 0.8 +/- 1.0, P < 0.05). In subjects undergoing myomectomy without concomitant surgery, the proportion of adhesion-free patients was 8 of 12 (67%) and 4 of 11 (36%) (not significant) in the gel and control groups, respectively, with a significant difference in the mean severity scores (P < 0.05). In subjects without uterine adhesions before myomectomy, 12 of 18 (67%) and 8 of 20 (40%) patients in the gel and control groups, respectively were adhesion-free (not significant), with a significant difference in the severity of uterine adhesions (P = 0.05).

CONCLUSIONS

Our results suggest that the auto-crosslinked hyaluronan gel may have a favourable safety profile and efficacious antiadhesive action following laparoscopic myomectomy.

Induction and assessment methods used in experimental adhesion studies

Infertility and intestinal obstruction are well-known complications, arising from adhesion formation after intra-abdominal operations. Basic principles of adhesion formation have been found through animal studies. In addition, examination of agents for the prevention of adhesions can be easily made using experimental studies. However, lack of uniformity in study design makes assessment of the efficacy of any prophylactic regimen difficult. In this review, the material and methods used in experimental studies designed for adhesion formation or prevention were evaluated in detail, with experimental studies published in the literature from 1960 to 2003 being evaluated. Several methods for adhesion induction have been described in the literature. Severity of the adhesion varies from method to method, with the main problem being the lack of uniform expression of study results. Extensive use of complex adhesion classification systems should be used to resolve this discordance between experimental studies.

Prevention of postsurgery-induced abdominal adhesions by electrospun bioabsorbable nanofibrous poly(lactide-co-glycolide)-based membranes

OBJECTIVES

The objective of this study was to evaluate the efficacy of nonwoven bioabsorbable nanofibrous membranes of poly(lactideco-glycolide) for prevention of postsurgery-induced abdominal adhesions.

SUMMARY BACKGROUND DATA

Recent reports indicated that current materials used for adhesion prevention have only limited success. Studies on other bioabsorbable materials using a new fabrication technique demonstrated the promising potential of generating an improved and inexpensive product that is suitable for a variety of surgical applications.

METHODS

All rats underwent a midline celiotomy. The cecum was identified and scored using an abrasive pad until serosal bleeding was noted on the anterior surface. A 1 x 1 cm of abdominal wall muscle was excised directly over the cecal wound. The celiotomy was then closed in 2 layers immediately (control) after a barrier was laid in between the cecum and the abdominal wall. All rats underwent a second celiotomy after 28 days to evaluate the extent of abdominal adhesions qualitatively and quantitatively.

RESULTS

Cecal adhesions were reduced from 78% in the control group to 50% in the group using biodegradable poly(lactide-co-glycolide) (PLGA) nonwoven nanofibrous membranes (n = 10, P = 0.2) and to 22% in the group using membranes containing PLGA and poly(ethylene glycol)/poly(D,L-lactide) (PEG-PLA) blends (n = 9, P = 0.03). Electrospinning method also enabled us to load an antibiotic drug Cefoxitin sodium (Mefoxin; Merck Inc., West Point, PA) with high efficacy. The electrospun PLGA/PEG-PLA membranes impregnated with 5 wt% cefoxitin sodium, which amounts to approximately 10% of the systemic daily dose typically taken after surgery in humans, completely prevented cecal adhesions (0%) in rats.

CONCLUSIONS

Electrospun nonwoven bioabsorbable nanofibrous membranes of poly(lactide-co-glycolide) were effective to reduce adhesions at the site of injury using an objective rat model. The membrane acted as a physical barrier but with drug-delivery capability. The combined advantages of composition adjustment, drug-loading capability, and easy placement handling (relatively hydrophobic) make these membranes potentially successful candidates for further clinical evaluations.

Reduction of neural adhesions by biodegradable autocrosslinked hyaluronic acid gel after injury of peripheral nerves: an experimental study

OBJECT

Adhesion formation is a serious problem in peripheral nerve surgery, frequently causing dysfunction and pain. The authors aimed to develop an objective biomechanical method of quantifying nerve adhesions and to use this technique for the evaluation of the efficacy of an autocrosslinked hyaluronic acid (HA) gel as an antiadhesion therapy.

METHODS

Thirty-three female Wistar rats underwent dissection, crush injury, or transection plus repair of the sciatic nerve. The nerves were or were not treated with the HA gel. Six weeks after surgery, the adhesions formed were assessed by measuring the peak force required to break the adhesions over a standardized area. Results of biomechanical measurements demonstrated that the peak force significantly increased as the severity of the injury increased. After using the HA gel to treat the nerve, the peak force was significantly reduced in rats with any of the three types of injuries; peak force decreased by 26% in the animals in the dissection group, 29% in the crush injury group, and 38% in the transection and repair group, compared with the untreated animals.

CONCLUSIONS

The biomechanical method described is an objective, quantitative technique for the assessment of nerve adherence to surrounding tissue. It will be a valuable tool in future studies on antiadhesion therapies. Furthermore, HA gel significantly reduces nerve adhesions after different types of nerve injuries.

Effectiveness of autocrosslinked hyaluronic acid gel after laparoscopic myomectomy in infertile patients: a prospective, randomized, controlled study

OBJECTIVE

To assess the efficacy of autocrosslinked hyaluronic gel in postsurgical adhesion prevention after laparoscopic myomectomy.

DESIGN

Prospective, randomized, controlled study.

SETTING

University of Naples "Federico II".Thirty-six infertile women with symptomatic myomas were randomly divided into two groups of 18 patients each.

INTERVENTION(S)

Laparoscopic myomectomy with subserous sutures or interrupted figure 8 sutures, with (group A) or without (group B) application of autocrosslinked hyaluronic acid (HA) gel.

MAIN OUTCOME MEASURE(S)

Rate of postsurgical adhesions at 60-90 days of follow-up. The rate of subjects who developed postoperative adhesions was significantly lower in group A in comparison with group B (27.8% vs. 77.8%). In both groups, the rate of adhesions was significantly higher in patients treated with interrupted figure 8 sutures than with subserous sutures.

CONCLUSION(S)

Autocrosslinked HA gel is a promising resorbable agent barrier for the reduction of postoperative adhesions after laparoscopic myomectomy. Moreover, the type of suture is a factor influencing the postsurgical adhesion formation.

Pathophysiology of intra-abdominal adhesion and abscess formation, and the effect of hyaluronan

BACKGROUND

Intra-abdominal adhesions and abscesses cause significant morbidity and mortality. The formation of fibrin in the abdominal cavity is a common pathophysiological pathway for both. The aim of this review was to investigate the pathophysiology of intra-abdominal adhesions and abscesses, and to explore the possible sites of action of hyaluronan.

METHODS

Data were reviewed from the literature using the Medline database.

RESULTS

Both surgery and peritonitis disturb the equilibrium between coagulation and fibrinolysis in the abdominal cavity in favour of the coagulation system. Hyaluronan-based agents reduce adhesion formation after surgery. Moreover, hyaluronan solution reduces abscess formation in experimental peritonitis. Possible mechanisms of action include mechanical separation of wound surfaces, improvement of peritoneal healing, modulation of the inflammatory response and enhanced fibrinolysis.

CONCLUSION

Diminished fibrin degradation is a common pathway for the formation of adhesions and abscesses. The potential of hyaluronan-based agents to reduce intra-abdominal adhesions and abscesses in abdominal surgery and sepsis is a promising new concept. Elucidating the mechanisms involved and the clinical application of hyaluronan in peritonitis are challenges for future research.

Effect of antiadhesive agents on peritoneal carcinomatosis in an experimental model

BACKGROUND

Auto-crosslinked polysaccharide hyaluronan-based solution (Hyalobarrier-gel) prevents postoperative adhesions. However, its effect on tumour growth is still unknown. The aim of the present study was therefore to investigate the impact on survival of intra-abdominally administered Hyalobarrier-gel, native hyaluronan (HA) and hyaluronan/carboxymethylcellulose (HA/CMC), after intraperitoneal tumour implantation.

METHODS

After receiving an intraperitoneal inoculum of the human HT29 colorectal cell line, 615 athymic nude mice were assigned randomly to five groups: groups 1 and 2 received Hyalobarrier-gel 20 mg/ml (n = 124) and 40 mg/ml (n = 126) respectively; groups 3 and 4 received HA (n = 120) and HA/CMC film (Seprafilm) (n = 123) respectively. The survival of each treated group was compared with that of group 5, the control, which had no treatment (n = 122).

RESULTS

As 34 of the 615 mice were not eligible, 581 animals were considered for the analysis. At 120 days, 136 animals (23.4 per cent) were still alive. At autopsy there was macroscopic absence of tumour in 75 cases (12.9 per cent). No statistically significant differences were found between the treatment and the control groups with respect to postoperative death and absence of tumour implantation. There was no difference in survival rate between the control group and groups treated with Hyalobarrier-gel, HA or HA/CMC.

CONCLUSION

Hyalobarrier-gel, HA and HA/CMC had no negative impact on the survival rate in mice that received an intraperitoneal implantation of HT29 colorectal human tumour cells.