Technique Advances in Enteroatmospheric Fistula Isolation After Open Abdomen: A Review and Outlook

An alternative negative pressure treatment for enteroatmospheric fistula resulting from small intestinal leakage caused by incision dehiscence

Background

To investigate the efficacy of an alternative negative pressure treatment for the treatment of enteroatmospheric fistula transformed from small intestinal leakage due to incision dehiscence after abdominal surgery.

Methods

Patients with an enteroatmospheric fistula from small intestinal leakage owing to incision dehiscence following abdominal surgery between January 2010 and December 2019 were retrospectively reviewed.

Results

A total of 83 patients (mean age: 38.3 ± 11.6 years; Body mass index: 19.9 ± 2.2 kg/m2) were enrolled. Of the 83 patients, 59 (71.1 %) achieved fistula closure. High-output fistula (Hazard ratio = 0.48; 95 % Confidence interval: 0.29-0.81; P = 0.006) and abdominal wall thickness >2 cm (Hazard ratio = 2.76; 95 % Confidence interval: 1.35-5.67; P = 0.006) were identified as factors affecting fistula closure. Lastly, 11/83 (13.3 %) patients exhibited re-dehiscence.

Conclusion

Appropriately applying the alternative negative pressure treatment may enable fistula closure in patients with enteroatmospheric fistula resulting from small intestinal leakage caused by incision dehiscence.

Whole Model Path Planning-Guided Multi-Axis and Multi-Material Printing of High-Performance Intestinal Implantable Stent

The problems of step effects, supporting material waste, and conflict between flexibility and toughness for 3D printed intestinal fistula stents are not yet resolved. Herein, the fabrication of a support-free segmental stent with two types of thermoplastic polyurethane (TPU) using a homemade multi-axis and multi-material conformal printer guided with advanced whole model path planning is demonstrated. One type of TPU segment is soft to increase elasticity, and the other is used to achieve toughness. Owing to advancements in stent design and printing, the obtained stents present three unprecedented properties compared to previous three-axis printed stents: i) Overcoming step effects; ii) Presenting comparable axial flexibility to a stent made of a single soft TPU 87A material, thus increasing the feasibility of implantation; and iii) Showing equivalent radial toughness to a stent made of a single hard TPU 95A material. Hence, the stent can resist the intestinal contractive force and maintain intestinal continuity and patency. Through implanting such stents to the rabbit intestinal fistula models, therapeutic mechanisms of reducing fistula output and improving nutritional states and intestinal flora abundance are revealed. Overall, this study develops a creative and versatile method to improve the poor quality and mechanical properties of medical stents.

Mesenchymal stem cell secretome-loaded fibrin glue improves the healing of intestinal anastomosis

Anastomotic leakage is a serious complication following gastrointestinal surgery and one of the leading causes of patient mortality. Despite the significant clinical and economic burden, there are currently no reliable treatment options to improve the healing of intestinal anastomosis and subsequently prevent anastomotic leakage. Recently, the development of regenerative medicine has shown promise for improving anastomotic healing. Recent studies have illustrated that stem cell-derived secretome can enhance tissue regeneration without the safety and ethical limitations of stem cell transplantation. Herein, we developed a fibrin glue topical delivery system loaded with mesenchymal stem cells (MSCs)-derived secretome for controlled delivery of bioactive factors, and evaluated its application potential in improving the healing of intestinal anastomosis. Under in vitro conditions, the MSCs secretome significantly promoted cell proliferation viability in a dose-dependent manner and resulted in the controlled release of growth factors via fibrin glue delivery. We established a rat surgical anastomotic model and experimentally found that MSCs secretome-loaded fibrin glue enhanced anastomotic bursting pressure, increased granulation tissue formation and collagen deposition, and significantly promoted anastomotic healing. Mechanistically, fibrin glue accelerated cell proliferation, angiogenesis, and macrophage M2 polarization at the surgical anastomotic site by releasing bioactive factors in the secretome, and it also alleviated the inflammatory response and cell apoptosis at the anastomotic site. Our results demonstrated for the first time that MSCs-derived secretome could promote the healing of intestinal anastomosis. Considering the accessibility and safety of the cell-free secretome, we believed that secretome-loaded fibrin glue would be a cell-free therapy to accelerate the healing of intestinal anastomosis with great potential for clinical translation.

4D-printed bilayer hydrogel with adjustable bending degree for enteroatmospheric fistula closure

Recently, four-dimensional (4D) shape-morphing structures, which can dynamically change shape over time, have attracted much attention in biomedical manufacturing. The 4D printing has the capacity to fabricate dynamic construction conforming to the natural bending of biological tissues, superior to other manufacturing techniques. In this study, we presented a multi-responsive, flexible, and biocompatible 4D-printed bilayer hydrogel based on acrylamide-acrylic acid/cellulose nanocrystal (AAm-AAc/CNC) network. The first layer was first stretched and then formed reversible coordination with Fe³⁺ to maintain this pre-stretched length; it was later combined with a second layer. The deformation process was actuated by the reduction of Fe³⁺ to Fe²⁺ in the first layer which restored it to its initial length. The deformation condition was to immerse the 4D construct in sodium lactate (LA-Na) and then expose it to ultraviolet (UV) light until maximal deformation was realized. The bending degree of this 4D construct can be programmed by modifying the pre-stretched lengths of the first layer. We explored various deformation steps in simple and complex constructs to verify that the 4D bilayer hydrogel can mimic the curved morphology of the intestines. The bilayer hydrogel can also curve in deionized water due to anisotropic volume change yet the response time and maximum bending degree was inferior to deformation in LA-Na and UV light. Finally, we made a 4D-printed bilayer hydrogel stent to test its closure effect for enteroatmospheric fistulas (EAFs) in vitro and in vivo. The results illustrate that the hydrogel plays a role in the temporary closure of EAFs. This study offers an effective method to produce curved structures and expands the potential applications of 4D printing in biomedical fields.

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A novel strategy to fabricate 4D-printed multi-responsive bilayer hydrogels is proposed.

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The deformation mechanism relies on shrinkage anisotropy between two layers in lactate sodium solution and ultraviolet.

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The 4D shape-morphing hydrogel can adapt to intestinal curvature for enteroatmospheric fistula closure.

Update on surgical management of enteroatmospheric fistulae in intestinal failure patients

PURPOSE OF REVIEW

The surgical management of enteroatmospheric fistula (EAF) in patients with intestinal failure represents a major challenge for a surgical team and requires proficiency in sepsis management, nutritional support and prehabilitation, beside expertise in visceral and abdominal wall surgery. This review provides an update on the current recommendations and evidence.

RECENT FINDINGS

Reconstructive surgery should be performed at a minimum of 6-12 months after last laparotomy. Isolation techniques and new occlusion devices may accelerate spontaneous EAF closure in selected cases. Chyme reinfusion supports enteral and parenteral nutrition. Stapler anastomosis and failure to close the fascia increase the risk of EAF recurrence. Posterior component separation, intraoperative fascial tension and biological meshes may be used to accommodate fascial closure.

SUMMARY

Timing of reconstructive surgery and previous optimal conservative treatment is vital for favorable outcomes. Wound conditions, nutritional support and general patient status should be optimal before attempting a definitive fistula takedown. Single stage procedures with autologous gut reconstruction and abdominal wall reconstruction can be complex but well tolerated.

Failure to Rescue (FTR) and Pitfalls in the Management of Complex Enteric Fistulas (CEF): From Rescue Surgery to Rescue Strategy

Purpose: Complex enteric fistulas (CEF) represent general surgeons’ nightmare. This paper aims to explore the impact on failure-to-rescue (FTR) rate of a standardised and integrated surgical and critical care step-up approach. Methods: This was a retrospective observational cohort study. Patients treated for CEF from 2009 to 2019 at Niguarda Hospital were included. Each patient was approached following a three-step approach: study phase, sepsis control and strategy definition phase, and surgical rescue phase. Results: Sixteen patients were treated for CEF. Seven fistulas were classified as complex entero-cutaneous (ECF) and nine as entero-atmospheric fistula (EAF). Median number of surgical procedures for fistula control before definitive surgical attempt was 11 (IQR 2–33.5). The median time from culprit surgery and the first access at Niguarda Hospital to definitive surgical attempt were 279 days (IQR 231–409) and 120 days (IQR 34–231), respectively. Median ICU LOS was 71 days (IQR 28–101), and effective hospital LOS was 117 days, (IQR 69.5–188.8). Three patients (18.75%) experienced spontaneous fistula closure after conversion to simple ECF, whereas 13 (81.25%) underwent definitive surgery for fistula takedown. Surgical rescue was possible in nine patients. Nine patients underwent multiple postoperative revision for surgical complications. Four patients failed to be rescued. Conclusion: An integrated step-up rescue strategy is crucial to standardise the approach to CEF and go beyond the basic surgical rescue procedure. The definition of FTR is dependent from the examined population. CEF patients are a unique cluster of emergency general surgery patients who may need a tailored definition of FTR considering the burden of postoperative events influencing their outcome.