Effect of Upper Abdomen Tissue Manipulation on Adhesion Formation between Injured Areas in a Laparoscopic Mouse Model

STAPLED FASCIAL CLOSURE VS. CONTINUOUS HAND-SEWN SUTURE: EXPERIMENTAL STUDY OF THE ABDOMINAL WALL ON PORCINE MODEL AND HUMAN CADAVER

BACKGROUND

One of the primary complications associated with large incisions in abdominal surgery is the increased risk of fascial closure rupture and incisional hernia development. The choice of the fascial closure method and closing with minimal tension and trauma is crucial for optimal results, emphasizing the importance of uniform pressure along the suture line to withstand intra-abdominal pressure.

AIMS

To evaluate the resistance to pressure and tension of stapled and sutured hand-sewn fascial closure in the abdominal wall.

METHODS

Nine abdominal wall flaps from human cadavers and 12 pigs were used for the experimentation. An abdominal defect was induced after the resection of the abdominal wall and the creation of a flap in the cadaveric model and after performing a midline incision in the porcine models. The models were randomized into three groups. Group 1 was treated with a one-layer hand-sewn small bite suture, Group 2 was treated with a two-layer hand-sewn small bite suture, and Group 3 was treated with a two-layer stapled closure. Tension measurements were assessed in cadaveric models, and intra-abdominal pressure was measured in porcine models.

RESULTS

In the human cadaveric model, the median threshold for fascial rupture was 300N (300-350) in Group 1, 400N (350-500) in Group 2, and 350N (300-380) in Group 3. Statistical comparisons revealed non-significant differences between Group 1 and Group 2 (p=0.072, p>0.05), Group 1 and Group 3 (p=0.346, p>0.05), and Group 2 and Group 3 (p=0.184, p>0.05). For porcine subjects, Group 1 showed a median pressure of 80 mmHg (85-105), Group 2 had a median of 92.5 mmHg (65-95), and Group 3 had a median of 102.5 mmHg (80-135). Statistical comparisons indicated non-significant differences between Group 1 and Group 2 (p=0.243, p>0.05), Group 1 and Group 3 (p=0.468, p>0.05), and Group 2 and Group 3 (p=0.083, p>0.05).

CONCLUSIONS

Stapled and conventional suturing resist similar pressure and tension thresholds.

Genetic Predisposition of Postoperative Adhesions Varies in Substrains of BALB/c Mice

Postoperative adhesions are a major clinical problem because of the associated infertility, chronic pain, bowel obstruction, and the associated costs. Variability in adhesion formation was suggested by clinical observations that apparently similar interventions can cause little to severe adhesions. This is supported by the presence of polymorphisms and genetic predisposition to develop adhesions in animal models and humans. We previously demonstrated differences in postoperative adhesions between different mouse strains. In this study, we aimed to investigate the variability in adhesion formation in inbred substrains of BALB/c mice. Since genetic differences in inbred substrains are minimal, they might be an opportunity to tackle the genetics of adhesion formation.

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.

Role of the peritoneal cavity in the prevention of postoperative adhesions, pain, and fatigue

A surgical trauma results within minutes in exudation, platelets, and fibrin deposition. Within hours, the denuded area is covered by tissue repair cells/macrophages, starting a cascade of events. Epithelial repair starts on day 1 and is terminated by day 3. If repair is delayed by decreased fibrinolysis, local inflammation, or factors in peritoneal fluid, fibroblast growth starting on day 3 and angiogenesis starting on day 5 results in adhesion formation. For adhesion formation, quantitatively more important are factors released into the peritoneal fluid after retraction of the fragile mesothelial cells and acute inflammation of the entire peritoneal cavity. This is caused by mechanical trauma, hypoxia (e.g., CO₂ pneumoperitoneum), reactive oxygen species (ROS; e.g., open surgery), desiccation, or presence of blood, and this is more severe at higher temperatures. The inflammation at trauma sites is delayed by necrotic tissue, resorbable sutures, vascularization damage, and oxidative stress. Prevention of adhesion formation therefore consists of the prevention of acute inflammation in the peritoneal cavity by means of gentle tissue handling, the addition of more than 5% N₂O to the CO₂ pneumoperitoneum, cooling the abdomen to 30°C, prevention of desiccation, a short duration of surgery, and, at the end of surgery, meticulous hemostasis, thorough lavage, application of a barrier to injury sites, and administration of dexamethasone. With this combined therapy, nearly adhesion-free surgery can be performed today. Conditioning alone results in some 85% adhesion prevention, barriers alone in 40%-50%.

Evaluation of a precise and measurable model for learning laparoscopic tissue handling

INTRODUCTION

Laparoscopic tissue handling is quite difficult to measure using virtual-reality laparoscopic simulators and box-trainer exercises, and therefore, completion time is the predominant performance measure for simulation-based laparoscopic training exercises. The purpose of this study was to evaluate the construct validity of a training and assessment model for precise laparoscopic handling of delicate tissue.

METHODS

Participants (n = 35) completed 2 progressively challenging laparoscopic tissue translocation exercises using delicate foam pieces and templates. Deidentified performances were scored using objective measures for tissue damage, accuracy, percentage complete, and completion time. Evaluation included multiple analysis of variance with repeated measures among the 3 groups as follows: medical students, residents and faculty who perform laparoscopic surgery less than once per week, and faculty members who perform laparoscopic surgery at least once per week.

RESULTS

The model demonstrated significant construct validity by discriminating performances between the types of shapes and templates and across the levels of surgical experience on all dimensions. A significant interaction effect between the level of expertise and the difficulty of the exercise revealed excellent discrimination between experienced laparoscopic surgeons and others.

DISCUSSION

This low-cost model provides an alternative or adjunct platform for laparoscopic training and assessment that requires precise and measurable handling of a delicate tissue.

Conditioning of the abdominal cavity reduces tumor implantation in a laparoscopic mouse model

Purpose

The addition of 4 % O₂ and 10 % N₂O to the CO₂ pneumoperitoneum (PP), together with slight cooling and humidification (conditioning), contributes to reducing adhesions by preventing mesothelial damage. We investigated the effect of peritoneal damage during laparoscopy on tumor implantation.

Methods

In Experiment 1, different tumor cell concentrations were injected into control mice without PP and into mice with 60-min dry CO₂PP (mesothelial damage). In Experiment 2, tumor cells were injected into control mice (group I) and in mice with mesothelial damage (group II). In groups III to VI, mesothelial damage was decreased by adding humidification, humidification + 10 % N₂O, humidification + 10 % N₂O + 4 % O₂, and conditioning, respectively.

Results

In Experiment 1, the tumors increased with the number of cells injected and with mesothelial damage in the abdominal cavity (p = 0.018) and abdominal wall (p < 0.0001). Experiment 2 confirmed that 60 min of dry CO₂PP increased the number of tumors in the abdominal cavity and wall (p = 0.026 and p = 0.003, respectively). The number of tumors was decreased in the abdominal cavity by conditioning (p = 0.030) and in the abdominal wall using humidified CO₂ (p = 0.032) or conditioning (p = 0.026).

Conclusions

Tumor implantation was enhanced by peritoneal damage (60 min of dry CO₂PP and desiccation), but this was prevented by conditioning. If confirmed in humans, conditioning would become important for oncologic surgery.

Peritoneal full-conditioning reduces postoperative adhesions and pain: a randomised controlled trial in deep endometriosis surgery

BACKGROUND

To translate the concept of full-conditioning (FC) from animal experiments to the human, and to evaluate the efficacy for adhesion prevention. FC consisted of decreasing acute inflammation by 86% CO2+ 10% N2O + 4% O2 for the pneumoperitoneum, cooling of the peritoneal cavity, humidification, heparinized rinsing solution and 5 mg of dexamethasone as demonstrated in animal models.

METHODS

A randomized controlled trial (RCT: NCT01344486) comparing standard laparoscopy with full conditioning together with a barrier in a 2/3 ratio in 44 women undergoing deep endometriosis surgery at KULeuven. The primary aim was reduction of adhesions. Secondary aims were CO2 resorption, postoperative pain and recovery. Randomization was performed after signing informed consent. Adhesion scoring during second look laparoscopy and pain scoring were done blindly.

RESULTS

In the FC group (n = 16) adhesions were completely prevented in 12/16 women whereas in the control group (n = 11) all women had severe adhesions (P < 0.0005). Also the area, density and severity of adhesions were less. (P <0.001). In the control group, severity, density and area of adhesions were strongly interrelated (P = 0.0001 for all areas) suggesting a common enhancing factor. In the FC group CO2 resorption (P < 0.001), postoperative pain (P < 0.001), and CRP concentrations (P < 0.01) were lower while clinical recovery was faster (P < 0.0001) and time to first flatus (P < 0.002) shorter.

IN CONCLUSION

This translational research confirms in the human the efficacy of FC in reducing CO2 resorption and adhesions with in addition less postoperative pain, lower postoperative CRP concentrations and an accelerated recovery.

Addition of nitrous oxide to the carbon dioxide pneumoperitoneum strongly decreases adhesion formation and the dose-dependent adhesiogenic effect of blood in a laparoscopic mouse model

OBJECTIVE

To evaluate the effect of addition of nitrous oxide (N2O) to the carbon dioxide (CO2) pneumoperitoneum (PP) and the effect of blood, plasma, or red blood cells (RBCs) on postoperative adhesions in a laparoscopic mouse model.

DESIGN

Prospective randomized controlled trial.

SETTING

University laboratory research center.

ANIMAL(S)

BALB/c female mice.

INTERVENTION(S)

The effect of adding to the 60-minute CO2 PP 5%, 10%, 25%, 50%, or 100% N2O on adhesion formation was evaluated. Subsequently the effect of adding 1 mL blood, or RBCs, or plasma and the effect of adding different concentrations of blood were studied. Finally, the effect of adding 10% N2O, 4% O2, or both to the CO2 was evaluated in a control group and after addition of blood.

MAIN OUTCOME MEASURE(S)

Postoperative adhesions after 7 days.

RESULT(S)

N2O strongly reduces adhesion formation with a full effect at a concentration of 5% or 10%. Adhesions increase linearly with 0.125 mL to 1 mL blood. In both the control group and after adding blood, 10% N2O is the most effective factor in prevention of adhesions.

CONCLUSION(S)

N2O, from concentrations of 5% upward, strongly prevents adhesion formation. Blood, mainly the plasma, increases adhesion formation. These data extend the concept of the role of acute inflammation and support the importance of good surgical practice with little bleeding and peritoneal cavity conditioning in adhesion prevention.

[Postoperative abdominal adhesions and their prevention in gynaecological surgery: II. How can they be prevented?]

This paper is the second of a two-part publication. The initial paper provided a comprehensive overview of the evidence on adhesions to allow gynaecological surgeons to be best informed on adhesions, their development, impact on patients, health systems and surgical outcomes. There is rising evidence that surgeons can take important steps to reduce the burden of adhesions. In this second paper, we review the various strategies to reduce the impact of adhesions, improve surgical outcomes and provide some practical proposals for action on adhesions. As well as improvements in surgical technique, developments in adhesion-reduction strategies and new agents offer a realistic possibility of reducing adhesion formation and improving outcomes for patients. They should be considered for use particularly in high-risk surgery and in patients with adhesiogenic conditions. Further research into new strategies to prevent adhesions more effectively through an improved surgical environment, new and combination devices and pharmacological agents should be encouraged. Formal recommendations would ensure better prioritisation of adhesion-reduction within the French health system. Patients should also be better informed of the risks of adhesions.

The impact of the learning curve on adhesion formation in a laparoscopic mouse model

OBJECTIVE

To evaluate the impact of surgeon training on adhesion formation in a laparoscopic mouse model. Laparoscopic surgery and bowel manipulation was demonstrated to enhance postoperative adhesion formation.

DESIGN

Prospective randomized, controlled trial.

SETTING

University laboratory research center.

ANIMAL(S)

200 BALB/c and 200 Swiss female mice.

INTERVENTION(S)

Adhesions were induced by opposing bipolar lesions and 60 minutes of pneumoperitoneum. Each surgeon operated on 80 mice (40 Swiss and 40 BALB/c), the only variable thus being his/her increasing experience. Some surgeons were already experienced gynecologists, others were starting their training.

MAIN OUTCOME MEASURE(S)

End points were the duration of surgery while performing the lesions. The adhesion formation was scored quantitatively (proportion and total) and qualitatively (extent, type, and tenacity) after 7 days.

RESULT(S)

With training, duration of surgery and adhesion formation decreased exponentially for all surgeons, whether experienced or not. Experienced surgeons had initially a shorter duration of surgery, less adhesion formation, and less de novo adhesions than inexperienced surgeons.

CONCLUSION(S)

These data suggest that laparoscopic skills improve with training, leading to a decrease in the duration of surgery and formation of adhesions. Therefore completion of a standardized learning curve should be mandatory when initiating adhesion formation studies both in laboratory or clinical setting.

Postoperative inflammation in the abdominal cavity increases adhesion formation in a laparoscopic mouse model

OBJECTIVE

To investigate acute inflammation in the peritoneal cavity in adhesion formation.

DESIGN

Prospective randomized, controlled trial.

SETTING

University laboratory research center.

ANIMAL(S)

9- to 10-week-old BALB/c female mice.

INTERVENTION(S)

In a laparoscopic mouse model, acute inflammation in the peritoneal cavity evaluated in CO(2) pneumoperitoneum enhanced adhesions, by CO(2) pneumoperitoneum plus manipulation, and in the latter group plus dexamethasone.

MAIN OUTCOME MEASURE(S)

Qualitative and quantitative adhesion scores and an acute inflammation score (neoangiogenesis, diapedesis, and leukocyte accumulation).

RESULT(S)

Adhesions at the lesion site were enhanced by the CO(2) pneumoperitoneum, further enhanced by manipulation, and decreased by the administration of dexamethasone. The acute inflammation scores (total, neoangiogenesis, diapedesis, and leukocyte accumulation) strongly correlated with the total adhesion score. Inflammation scores were similar at both the surgical lesion and the parietal peritoneum.

CONCLUSION(S)

Acute inflammation of the entire peritoneum cavity is an important mechanism involved in adhesion formation and enhances adhesion formation at the lesion site.