Effects of CO2 insufflation and laparotomy on wound healing in mice

The degree of local inflammatory response after colonic resection depends on the surgical approach: an observational study in 61 patients

Background

Clinical data indicate that laparoscopic surgery reduces postoperative inflammatory response and benefits patient recovery. Little is known about the mechanisms involved in reduced systemic and local inflammation and the contribution of reduced trauma to the abdominal wall and the parietal peritoneum.

Methods

Included were 61 patients, who underwent elective colorectal resection without intraabdominal complications; 17 received a completely laparoscopic, 13 a laparoscopically- assisted procedure and 31 open surgery. Local inflammatory response was quantified by measurement of intraperitoneal leukocytes and IL-6 levels during the first 4 days after surgery.

Results

There was no statistical difference between the groups in systemic inflammatory parameters and intraperitoneal leukocytes. Intraperitoneal interleukin-6 was significantly lower in the laparoscopic group than in the laparoscopically-assisted and open group on postoperative day 1 (26.16 versus 43.25 versus 40.83 ng/ml; p = 0.001). No difference between the groups was recorded on POD 2–4. Intraperitoneal interleukin-6 showed a correlation with duration of hospital stay on POD 1 (0.233, p = 0.036), but not on POD 2–4.

Patients who developed a surgical wound infection showed higher levels of intraperitoneal interleukin-6 on postoperative day 2–4 (POD 2: 42.56 versus 30.02 ng/ml, p = 0.03), POD 3: 36.52 versus 23.62 ng/ml, p = 0.06 and POD 4: 34.43 versus 19.99 ng/ml, p = 0.046). Extraabdominal infections had no impact.

Conclusion

The analysis shows an attenuated intraperitoneal inflammatory response on POD 1 in completely laparoscopically-operated patients, associated with a quicker recovery. This effect cannot be observed in patients, who underwent a laparoscopically-assisted or open procedure. Factors inflicting additional trauma to the abdominal wall and parietal peritoneum promote the intraperitoneal inflammation process.

Impact of intraoperative temperature and humidity on healing of intestinal anastomoses

PURPOSE

Clinical data indicate that laparoscopic surgery has a beneficial effect on intestinal wound healing and is associated with a lower incidence of anastomotic leakage. This observation is based on weak evidence, and little is known about the impact of intraoperative parameters during laparoscopic surgery, e.g., temperature and humidity.

METHODS

A small-bowel anastomosis was formed in rats inside an incubator, in an environment of stable humidity and temperature. Three groups of ten Wistar rats were operated: a control group (G1) in an open surgical environment and two groups (G2 and G3) in the incubator at a humidity of 60 % and a temperature of 30 and 37 °C (G2 and G3, respectively). After 4 days, bursting pressure and hydroxyproline concentration of the anastomosis were analyzed. The tissue was histologically examined. Serum levels of C-reactive-protein (CRP) were measured.

RESULTS

No significant changes were seen in the evaluation of anastomotic stability. Bursting pressure was very similar among the groups. Hydroxyproline concentration in G3 (36.3 μg/g) was lower by trend (p = 0.072) than in G1 (51.7 μg/g) and G2 (46.4 μg/g). The histological evaluation showed similar results regarding necrosis, inflammatory cells, edema, and epithelization for all groups. G3 (2.56) showed a distinctly worse score for submucosal bridging (p = 0.061) than G1 (1.68). A highly significant increase (p = 0.008) in CRP was detected in G3 (598.96 ng/ml) compared to G1 (439.49 ng/ml) and G2 (460 ng/ml).

CONCLUSION

A combination of high temperature and humidity during surgery induces an increased systemic inflammatory response and seems to be attenuating the early regeneration process in the anastomotic tissue.

Evaluation of the effects of carbon dioxide pneumoperitoneum on abdominal wall wound healing in rats undergoing segmental resection and anastomosis of the left colon

PURPOSE

To evaluate the influence of carbon dioxide pneumoperitoneum on abdominal wall wound healing in rats.

METHODS

Eighty rats underwent laparotomy, segmental left colon resection, and anastomosis. The animals were divided into three experimental groups and one control group: EI = pneumoperitoneum for 30 minutes before laparotomy (n=20); EII = pneumoperitoneum for 30 minutes after abdominal closure (n=20); EIII = pneumoperitoneum for 30 minutes before laparotomy and 30 minutes after abdominal closure (n=20); C = control group, without pneumoperitoneum (n=20). In each group, 10 animals were killed 7 days and 10 animals 14 days postoperatively. A segment of the abdominal wall was resected and subjected to tensile strength testing. Another segment of abdominal muscle was used for histopathological analysis; the specimens were fixed in formalin and stained with hematoxylin and eosin.

RESULTS

There were no differences in histopathology and tensile strength values among animals in the experimental and control groups 7 or 14 days after surgery.

CONCLUSION

Under the present experimental conditions, carbon dioxide pneumoperitoneum did not interfere with abdominal wall wound healing.

Study on adhesion formation and the healing of colon anastomosis in rats with induced peritoneal sepsis

PURPOSE

To evaluate the effects of abdominal sepsis on adhesion formation and colon anastomosis healing in rats.

METHODS

Forty rats were distributed in two groups containing 20 rats each for left colon anastomosis in the presence (Group S) or absence (Group N) of induced sepsis by cecal ligation and puncture. Each group was divided into subgroups for euthanasia on the third (N3 and S3) or seventh (N7 or S7) post-operative day. The amount of adhesions was evaluated and a segment of the colon was removed for histopathologic analysis, bursting strength assessment, hydroxyproline and the determination of tissue collagen.

RESULTS

The subjects which underwent cecal ligation and puncture presented a higher amount of intra-abdominal adherences in both third (p=0,00) and seventh (p=0,00) post-operatory days. Smaller bursting strengths were found in the S3 subgroup, and greater bursting strengths were found in the S7 subgroup. There was no difference in the variations on the concentrations of hydroxyproline, tissue collagen and histopathology.

CONCLUSIONS

The peritoneal infection which was developed by cecal ligation and puncture raised the amount of intra-cavitary adhesions. There was a decrease in the amount of colonic anastomosis on the third post-operatory day with a following raise on the seventh without any effects on other healing parameters.

Does metoclopramide impair anastomotic healing of the left colon of rats?

PURPOSE: To evaluate the effects of metoclopramide on the formation of adhesion and the healing of left colonic anastomoses in rats. METHODS: Forty rats underwent sectioning of the left colon and end-to-end anastomosis and were divided into two groups of 20 animals for the administration of metoclopramide (experimental group - E) or saline solution (control group - C). Each group was divided into subgroups of 10 animals each to be killed on the third (E3 and C3) or seventh postoperative day (E7 and C7). Adhesion was assessed, and a colonic segment containing the anastomosis was removed for analysis of breaking strength and hydroxyproline concentration. RESULTS: There were no deaths or dehiscence on the 3rd postoperative day. There was one death and one blocked anastomotic dehiscence in the E7 group. No significant differences between groups were found in the analysis of clinical outcome, intra-cavity adhesion, adhesion to the anastomosis or breaking strength on the 3rd and 7th postoperative day. Hydroxyproline concentration was higher in the control group on the 3rd (p=0.006) but not on the 7th postoperative day (p=0.241). CONCLUSION: Metoclopramide did not have harmful effects on the healing of intestinal anastomoses in rats.

Impact of pressure and gas type on adhesion formation and biomaterial integration in laparoscopy

BACKGROUND

Laparoscopic mesh repair of inguinal and incisional hernias has been widely adopted. Nevertheless, knowledge about the impact of pneumoperitoneum on mesh integration is rare. The present study investigates pressure and gas-dependent effects of pneumoperitoneum on adhesion formation and biomaterial integration in a standardized animal model.

METHODS

Laparoscopic intraperitoneal onlay mesh implantation (IPOM) was performed in 32 female chinchilla rabbits using CO(2) or helium for pneumoperitoneum. Intra-abdominal pressures were 3 or 6 mmHg. Animals were killed after 21 days, and the abdominal wall was explanted for subsequent histopathological examinations. Adhesions were assessed qualitatively with a scoring system, and the adhesion surface was analyzed semiquantitatively by planimetry. Infiltration of macrophages (CD68), expression of matrix metalloproteinase 13 (MMP-13), and cell proliferation (Ki67) were analyzed at the mesh to host interface by immunohistochemistry. The collagen type I/III ratio was analyzed by cross-polarization microscopy to determine the quality of mesh integration.

RESULTS

After 21 days, perifilamental infiltration with macrophages (CD68) and percentage of proliferating cells (Ki67) were highest after 6 mmHg of CO(2) pneumoperitoneum. The extent of adhesions, as well as the expression of MMP-13 and the collagen type I/III ratio, were similar between groups.

CONCLUSIONS

Our experiments showed no pressure or gas-dependent alterations of adhesion formation and only minor effects on biomaterial integration. Altogether, there is no evidence for a clinically negative effect of CO(2) pneumoperitoneum.

Effect of carnitine on cutaneous wound healing in immunosuppressed rats

BACKGROUND

The wound is ischemic in nature. Chronic steroid administration impairs wound healing by changing enzymes in the glycolytic pathway. Carnitine supplementation may help to restore the energy deficiency caused by chronic steroid administration in the wound. The aim of this study was to evaluate the effect of carnitine on impaired wound healing.

METHODS

The study was conducted in three groups. Surgical intervention was a 4 cm long midline skin incision at the back. In Group A, eight rats received methylprednisolone for 7 d prior to surgical intervention, and it was continued until the end of the experiment. In Group B, 12 rats received methylprednisolone for 7 d prior to surgical intervention. After surgery, methylprednisolone injection was continued and carnitine was supplemented until the end of the experiment. In Group C, eight rats received no medication. The wound of half of the animals in each group was harvested on the seventh day after surgical intervention and the remaining on the 14th d. Tensile strength and hydroxyproline content were measured in all groups.

RESULTS

There was no significant difference in parameters in any of the groups on day seven. On day 14, all parameters were statistically different between methylprednisolone and control groups (P < 0.05). Values for tensile strength were higher in the methylprednisolone/carnitine group compared with methylprednisolone group (P < 0.05). Carnitine administration had also increased hydroxyproline levels in the methylprednisolone/carnitine group compared with the control group (P < 0.05).

CONCLUSIONS

Carnitine is shown to increase tensile strength of the wound when supplemented to immunosuppressed rats in which wound healing is impaired by methylprednisolone.

Improved abdominal wall wound healing by helium pneumoperitoneum

BACKGROUND

Despite widespread use of the endoscopic technique in the treatment of inguinal and incisional hernias, knowledge about its impact on abdominal wall wound healing is rare. Questions remain regarding the risk of port-site hernias and hernia recurrence. The current study investigated the gas-dependent effects of pneumoperitoneum on laparotomy wound healing.

METHODS

Laparotomy was performed in 54 male Sprague-Dawley rats. A carbon dioxide (n = 18) or helium (n = 18) pneumoperitoneum of 3 mmHg was maintained before and after laparotomy, with an overall duration of 30 min. The rats in the control group (n = 18) received no pneumoperitoneum. The animals were killed after 5 and 10 days, and the abdominal wall was explanted for subsequent histopathologic examinations of the laparotomy wound. The granuloma formation in hematoxylin and eosin-stained sections was analyzed. Infiltration of macrophages (CD68) and expression of matrix metalloproteinases (MMP-8 and MMP-13) were examined by immunohistochemistry. The collagen type 1 to type 3 ratio was investigated by cross-polarization microscopy after Sirius Red staining.

RESULTS

After 5 and 10 days, the percentages of CD68-positive cells, granuloma formation, and expression of MMP-8 did not differ between the groups. In contrast, after both 5 and 10 days, the expression of MMP-13 and the collagen 1 to 3 ratio were significantly higher after helium pneumoperitoneum than in the control animals.

CONCLUSION

The results suggest that helium pneumoperitoneum may ameliorate wound healing within the abdominal wall and could therefore represent a beneficial gas for endoscopic hernia repair.

Gas-related impact of pneumoperitoneum on systemic wound healing

INTRODUCTION

The aim of the present study was to investigate the gas-dependent effects of pneumoperitoneum on wound healing distant from the abdomen.

MATERIALS AND METHODS

Dorsal skin incisions were performed in 54 male Sprague-Dawley rats. A CO(2) or a helium pneumoperitoneum of 3 mmHg was maintained before, with an overall duration of 30 min (each n = 18). Rats in the control group received laparotomy only (n = 18). Animals were killed after 5 and 10 days. The infiltration of macrophages (CD 68), expression of matrix metalloproteinase 13 (MMP-13) and collagen I/III ratios were analysed in the dorsal skin wounds.

RESULTS

Both after 5 and 10 days, infiltration of macrophages and expression of MMP-13 were greatest after helium pneumoperitoneum. After 5 days, collagen I/III ratio was significantly increased in the helium group. After 10 days, collagen I/III ratio was lowest in the CO(2) group.

CONCLUSION

Our results suggest beneficial effects on systemic wound healing for helium pneumoperitoneum as compared to CO(2).

Laparoscopy and collagen metabolism

The collagens represent a vital component within the wound healing process and physiological scar formation. Therefore, analysing the influence of new operative procedures on collagen metabolism is of great surgical interest. As the endoscopic technique has, nowadays, become routinely applied for diverse abdominal diseases worldwide, we present a review of literature facing its impact on collagen biology.