Tissue-type plasminogen activator prevents abscess formation but does not affect healing of bowel anastomoses and laparotomy wounds in rats with secondary peritonitis

Experimental models of high-risk bowel anastomosis in rats: A systematic review

BACKGROUND

Anastomotic leaks remain one of the most dreaded complications in gastrointestinal surgery causing significant morbidity, that negatively affect the patients' quality of life. Experimental studies play an important role in understanding the pathophysiological background of anastomotic healing and there are still many fields that require further investigation. Knowledge drawn from these studies can lead to interventions or techniques that can reduce the risk of anastomotic leak in patients with high-risk features. Despite the advances in experimental protocols and techniques, designing a high-quality study is still challenging for the investigators as there is a plethora of different models used.

AIM

To review current state of the art for experimental protocols in high-risk anastomosis in rats.

METHODS

This systematic review was performed according to The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. To identify eligible studies, a comprehensive literature search was performed in the electronic databases PubMed (MEDLINE) and Scopus, covering the period from conception until 18 October 2023.

RESULTS

From our search strategy 102 studies were included and were categorized based on the mechanism used to create a high-risk anastomosis. Methods of assessing anastomotic healing were extracted and were individually appraised.

CONCLUSION

Anastomotic healing studies have evolved over the last decades, but the findings are yet to be translated into human studies. There is a need for high-quality, well-designed studies that will help to the better understanding of the pathophysiology of anastomotic healing and the effects of various interventions.

Use of Tissue Plasminogen Activator in Abdominal Abscesses in Children-A Single-Center Randomized Control Trial

PURPOSE

To establish the efficacy of once-per-day intracavitary tissue plasminogen activator (tPA) in the treatment of pediatric intra-abdominal abscesses.

METHODS

A single-center prospective, double-blinded, randomized controlled trial of the use of intracavitary tPA in abdominal abscesses in children. Patients were randomized to either tPA-treatment or saline-treatment groups. Primary outcome was drainage catheter dwell (hours). Secondary outcomes were length of hospital stay, times to discharge, clinical and sonographic resolution, and adverse events (AEs).

RESULTS

Twenty-eight children were randomized to either group (n = 14 each). Demographics between groups were not significantly different (age P = .28; weight P = .40; gender P = .44). There were significantly more abscesses in the tPA-treated group (P = .03). Abscesses were secondary to perforated appendicitis (n = 25) or postappendectomy (n = 3). Thirty-four abscesses were drained, 4 aspirated, 3 neither drained/aspirated. There was no significant difference in number of drains (P = .14), drain size (P = .19), primary outcome (P = .077), or secondary outcomes found. No procedural or intervention drug-related AEs occurred. No patient in the saline-treated group required to be switched/treated with tPA.

CONCLUSION

No significant difference in the length of catheter dwell time, procedure time to discharge, or time to resolution was found. Intracavitary tPA was not associated with morbidity or mortality. The results neither support nor negate routine use of tPA in the drainage of intra-abdominal abscess in children. It is possible that a multicentre study with a larger number of patients may answer this question more definitively.

Efficacy and Safety of Ultrapure Alginate-Based Anti-Adhesion Gel in Experimental Peritonitis

BACKGROUND

Intra-abdominal infection may lead to adhesion and abscess formation. An adhesion barrier can reduce these complications but also aggravate intra-peritoneal infection, causing the opposite effects. The fear of infection propagation has limited clinical adhesion barrier use in a contaminated or infected abdomen. This study evaluated both adhesion and abscess reduction and infection propagation of a new ultrapure alginate-based anti-adhesive barrier gel in a rat peritonitis model.

METHODS

In 64 male Wistar rats, bacterial peritonitis was induced via intra-abdominal injection of a mixture of sterile feces, 10(5) colony-forming units (CFU) of Escherichia coli, and 10(4) CFU of Bacteroides fragilis. Surgical debridement and peritoneal lavage were performed 1 h after inoculation. Animals were randomly allocated in equal numbers to a control group or an alginate gel group. Animals were sacrificed on day five post-operatively. Death and the presence and size of intra-abdominal abscesses were noted, and adhesions were scored. All outcomes were compared in the two groups.

RESULTS

Seventeen rats (27%) died prematurely without any difference between the groups. Of the surviving rats in the alginate gel group, 88% developed abscesses vs. 100% of the control group. There was no significant difference in the abscess scores or incidence rates of adhesion formation between the groups. The adhesion scores were lower for the alginate gel group compared with control animals (p=0.04).

CONCLUSION

Ultrapure alginate gel reduces adhesion severity but not abscesses. The gel seemed to be safe, not aggravating intra-peritoneal infection in this abdominal infection model.

Everolimus-induced loss of wound strength can be prevented by a short postoperative delay in its administration

The use of mammalian target of rapamycin inhibitors coincides with an increased incidence of surgical complications. In previous experiments, serious negative effects of postoperative everolimus on anastomotic strength were found. This study aims to investigate if delayed drug administration can prevent loss of wound strength. Ten groups of Wistar rats each received daily oral doses of 1.0 or 2.0 mg/kg everolimus, starting the day of anastomotic construction in both ileum and colon, or 1, 2, 3, or 4 days later. The 11th group received saline. Seven days later, wound strength in anastomoses and in the abdominal wall and wound hydroxyproline levels were measured. Mean wound strength was significantly and dose-dependently reduced if everolimus was started on the day of operation. In ileum and colon, strength was not affected if drug administration was delayed until the third or second day, respectively. In abdominal fascia, this was the case only if everolimus was withheld until day 4. In general, changes in wound hydroxyproline content showed similarities to changes in wound strength. Thus, delaying administration of everolimus for 2-4 days after operation can prevent a serious loss of wound strength, both in the intestine and in the abdominal fascia.

Timing and Dose of Tissue Plasminogen Activator to Prevent Abscess Formation After Surgical Treatment of Secondary Peritonitis in the Rat

Early administration of fibrinolytics after surgical treatment of peritonitis in the rat reduces abscess formation. The current study investigates the effect of various treatment protocols using intraperitoneal recombinant tissue plasminogen activator (rtPA). Peritonitis was induced in rats and surgical debridement was performed after 1 hour. Animals were treated with rtPA at different time points. Abdominal fluid samples were taken at 24, 72, and 120 hours for cytokine measurements and cell counts. After 5 days the abdomen was inspected for abscesses. Early administration of rtPA significantly reduced the number of rats with abscesses and the abscess load per rat. Delayed treatment significantly reduced abscess load but not the incidence of abscesses. No meaningful differences in the local inflammatory response were found. rtPA was most effective when applied early and continued for 72 hours, although mortality increased after prolonged treatment. rtPA consistently reduces intra-abdominal abscess formation, and a clinical study seems warranted.