Intraoperative assessment of microperfusion with visible light spectroscopy for prediction of anastomotic leakage in colorectal anastomoses

Flap Monitoring Techniques: A Review

Postoperative tissue flap vitality monitoring enables early detection of clinical complications, allowing for intervention. Timely re-operation can prevent the need for extensive correction procedures, thus reducing healthcare costs and hospitalization time. Statistics show that monitoring can increase the success rate of flap survival to 95% or higher. However, despite the significant progress in monitoring techniques, major and minor complications, leading to the loss of the flap, still occur. This clinical application review aims to provide a comprehensive overview of the recent advancements and findings in flap surgery reconstructions, transplants, and systems for their postoperative assessment. The literature from the years 1925 to 2024 has been reviewed to capture previous and current solutions for monitoring flap vitality. Clinically acclaimed methods and experimental techniques were classified and reviewed from a technical and clinical standpoint. Physical examination, metabolism change, ultrasound method, and electromagnetic (EM) radiation-based measurement methods were carefully evaluated from the perspective of their considered applications. Guidelines aiding engineers in the future design and development process of monitoring systems were proposed. This paper provides a comprehensive overview of the monitoring techniques used in postoperative flap vitality monitoring. It also gives an overview of each approach and potential ways for future development.

Clinical Utility of Laser Speckle Contrast Imaging and Real-Time Quantification of Bowel Perfusion in Minimally Invasive Left-Sided Colorectal Resections

BACKGROUND

Left-sided colorectal surgery demonstrates high anastomotic leak rates, with tissue ischemia thought to influence outcomes. Indocyanine green is commonly used for perfusion assessment, but evidence remains mixed for whether it reduces colorectal anastomotic leaks. Laser speckle contrast imaging provides dye-free perfusion assessment in real-time through perfusion heat maps and quantification.

OBJECTIVE

This study investigates the efficacy of advanced visualization (indocyanine green versus laser speckle contrast imaging), perfusion assessment, and utility of laser speckle perfusion quantification in determining ischemic margins.

DESIGN

Prospective intervention group using advanced visualization with case-matched, retrospective control group.

SETTINGS

Single academic medical center.

PATIENTS

Forty adult patients undergoing elective, minimally invasive, left-sided colorectal surgery.

INTERVENTIONS

Intraoperative perfusion assessment using white light imaging and advanced visualization at 3 time points: T1-proximal colon after devascularization, before transection, T2-proximal/distal colon before anastomosis, and T3-completed anastomosis.

MAIN OUTCOME MEASURES

Intraoperative indication of ischemic line of demarcation before resection under each visualization method, surgical decision change using advanced visualization, post hoc laser speckle perfusion quantification of colorectal tissue, and 30-day postoperative outcomes.

RESULTS

Advanced visualization changed surgical decision-making in 17.5% of cases. For cases in which surgeons changed a decision, the average discordance between the line of demarcation in white light imaging and advanced visualization was 3.7 cm, compared to 0.41 cm ( p  = 0.01) for cases without decision changes. There was no statistical difference between the line of ischemic demarcation using laser speckle versus indocyanine green ( p  = 0.16). Laser speckle quantified lower perfusion values for tissues beyond the line of ischemic demarcation while suggesting an additional 1 cm of perfused tissue beyond this line. One (2.5%) anastomotic leak occurred in the intervention group.

LIMITATIONS

This study was not powered to detect differences in anastomotic leak rates.

CONCLUSIONS

Advanced visualization using laser speckle and indocyanine green provides valuable perfusion information that impacts surgical decision-making in minimally invasive left-sided colorectal surgeries. See Video Abstract .

UTILIDAD CLNICA DE LAS IMGENES DE CONTRASTE MOTEADO CON LSER Y LA CUANTIFICACIN EN TIEMPO REAL DE LA PERFUSIN INTESTINAL EN RESECCIONES COLORRECTALES DEL LADO IZQUIERDO MNIMAMENTE INVASIVAS

ANTECEDENTES:La cirugía colorrectal del lado izquierdo demuestra altas tasas de fuga anastomótica, y se cree que la isquemia tisular influye en los resultados. El verde de indocianina se utiliza habitualmente para evaluar la perfusión, pero la evidencia sobre si reduce las fugas anastomóticas colorrectales sigue siendo contradictoria. Las imágenes de contraste moteado con láser proporcionan una evaluación de la perfusión sin colorantes en tiempo real a través de mapas de calor de perfusión y cuantificación.OBJETIVO:Este estudio investiga la eficacia de la evaluación de la perfusión mediante visualización avanzada (verde de indocianina versus imágenes de contraste moteado con láser) y la utilidad de la cuantificación de la perfusión con moteado láser para determinar los márgenes isquémicos.DISEÑO:Grupo de intervención prospectivo que utiliza visualización avanzada con un grupo de control retrospectivo de casos emparejados.LUGARES:Centro médico académico único.PACIENTES:Cuarenta pacientes adultos sometidos a cirugía colorrectal electiva, mínimamente invasiva, del lado izquierdo.INTERVENCIONES:Evaluación de la perfusión intraoperatoria mediante imágenes con luz blanca y visualización avanzada en tres puntos temporales: T1-colon proximal después de la devascularización, antes de la transección; T2-colon proximal/distal antes de la anastomosis; y T3-anastomosis completa.PRINCIPALES MEDIDAS DE VALORACIÓN:Indicación intraoperatoria de la línea de demarcación isquémica antes de la resección bajo cada método de visualización, cambio de decisión quirúrgica mediante visualización avanzada, cuantificación post-hoc de la perfusión con láser moteado del tejido colorrectal y resultados posoperatorios a los 30 días.RESULTADOS:La visualización avanzada cambió la toma de decisiones quirúrgicas en el 17,5% de los casos. Para los casos en los que los cirujanos cambiaron una decisión, la discordancia promedio entre la línea de demarcación en las imágenes con luz blanca y la visualización avanzada fue de 3,7 cm, en comparación con 0,41 cm (p = 0,01) para los casos sin cambios de decisión. No hubo diferencias estadísticas entre la línea de demarcación isquémica utilizando láser moteado versus verde de indocianina (p = 0,16). El moteado con láser cuantificó valores de perfusión más bajos para los tejidos más allá de la línea de demarcación isquémica y al mismo tiempo sugirió 1 cm adicional de tejido perfundido más allá de esta línea. Se produjo una fuga anastomótica (2,5%) en el grupo de intervención.LIMITACIONES:Este estudio no tuvo el poder estadístico suficiente para detectar diferencias en las tasas de fuga anastomótica.CONCLUSIONES:La visualización avanzada utilizando moteado láser y verde de indocianina proporciona información valiosa sobre la perfusión que impacta la toma de decisiones quirúrgicas en cirugías colorrectales mínimamente invasivas del lado izquierdo. (Traducción-Dr. Ingrid Melo).

Validation of an endoscopic anastomotic grading score as an intraoperative method for assessing stapled rectal anastomoses

PURPOSE

Anastomotic leak is a dreaded complication of colorectal surgery. An endoscopic grading score of the perianastomotic mucosa has been previously developed at our institution (UCI) to assess colorectal anastomotic integrity. The objective of this study is to validate the UCI anastomotic score and determine its impact in anastomotic failure.

METHODS

As a follow-up study of the UCI grading score implementation during 2011 to 2014, patients undergoing stapled colorectal anastomoses after sigmoidectomy or proctectomy at a single institution from 2015 to 2018 were retrospectively reviewed. Patients were grouped into three tiers based on endoscopic appearance (grade 1, circumferentially normal mucosa; grade 2, ischemia/congestion < 30% of circumference; grade 3, ischemia/congestion > 30% of circumference).

RESULTS

On the basis of endoscopic mucosal evaluation, grade 1 anastomosis was observed in 299 patients (94%), grade 2 anastomosis in 14 patients (4.4%), and grade 3 anastomosis in 5 patients (1.6%). All grade 3 classifications were immediately and successfully revised intraoperatively with reclassification as a grade 1 anastomosis. The anastomotic leak rate of the follow-up study period from 2015 to 2018 was 6.4% which was lower compared to the anastomotic leak rate of 12.2% in the original study period from 2011 to 2014 (p = 0.07). Anastomotic leak rate for the entire patient series was 8.5%. A grade 2 anastomosis was associated with higher anastomotic leak rate compared to a grade 1 anastomosis (35.7% vs. 7.4%, p < 0.05). None of the five grade 3 anastomoses resulted in an anastomotic leak upon revision.

CONCLUSION

This study further validates the anastomotic grading score and suggests that its systematic implementation can result in a reduction in anastomotic leaks.

Intraoperative Anastomotic Evaluation Methods: Rigid Proctoscopy Versus Flexible Endoscopy

INTRODUCTION

Rigid proctosigmoidoscopy (RP) and flexible sigmoidoscopy (FS) are two modalities commonly used for intraoperative evaluation of colorectal anastomoses. This study seeks to determine whether there is an association between the endoscopic modality used to evaluate colorectal anastomoses and the rate of anastomotic leak (AL), organ space infection, and overall infectious complication.

METHODS

The 2012-2018 American College of Surgeons National Surgical Quality Improvement Program database was queried for patients undergoing colorectal anastomoses. Anastomotic evaluation method (RP versus FS) was identified by Current Procedural Terminologycoding and used for group classification. Outcomes measured included AL, organ space infections, and overall infection. Multivariable logistic regression analysis for predicting AL was performed.

RESULTS

We identified 7100 patients who underwent a colorectal anastomosis with intraoperative endoscopic evaluation. RP was utilized in 3397 (47.8%) and FS in 3703 (52.2%) patients. RP was used more commonly in diverticulitis (44.5% versus 36.2%, P < 0.01), while FS was used more frequently in malignancy (47.5% versus 36.7%, P < 0.01). Anastomotic evaluation with FS was associated with lower rates of organ space infection (3.8% versus 4.8%, P = 0.025) and AL (2.9% versus 3.8%, P = 0.028) compared to RP. On multivariate logistic regression modeling, anastomotic evaluation with RP was associated with a higher risk of AL (odds ratio 1.403, 95% CI 1.028-1.916, P = 0.033) compared to FS.

CONCLUSIONS

Compared to FS, rigid proctosigmoidoscopic evaluation of a colorectal anastomosis was associated with an increased rate of AL and organ space infection.

Time required for indocyanine green fluorescence emission for evaluating bowel perfusion in left-sided colon and rectal cancer surgery

BACKGROUND

Indocyanine green fluorescence imaging (ICG-FI) has been reported to be useful in reducing the incidence of anastomotic leakage (AL) in colectomy. This study aimed to investigate the correlation between the required time for ICG fluorescence emission and AL in left-sided colon and rectal cancer surgery using the double-stapling technique (DST) anastomosis.

METHODS

This retrospective study included 217 patients with colorectal cancer who underwent left-sided colon and rectal surgery using ICG-FI-based perfusion assessment at our department between November 2018 and July 2022. We recorded the time required to achieve maximum fluorescence emission after ICG systemic injection and assessed its correlation with the occurrence of AL.

RESULTS

Among 217 patients, AL occurred in 21 patients (9.7%). The median time from ICG administration to maximum fluorescence emission was 32 s (range 25-58 s) in the AL group and 28 s (range 10-45 s) in the non-AL group (p < 0.001). The cut-off value for the presence of AL obtained from the ROC curve was 31 s. In 58 patients with a required time for ICG fluorescence of 31 s or longer, the following risk factors for AL were identified: low preoperative albumin [3.4 mg/dl (range 2.6-4.4) vs. 3.9 mg/dl (range 2.6-4.9), p = 0.016], absence of preoperative mechanical bowel preparation (53.8% vs. 91.1%, p = 0.005), obstructive tumor (61.5% vs. 17.8%, p = 0.004), and larger tumor diameter [65 mm (range 40-90) vs. 35 mm (range 4.0-100), p < 0.001].

CONCLUSION

The time required for ICG fluorescence emission was associated with AL.

Intraoperative bowel perfusion assessment methods and their effects on anastomotic leak rates: meta-analysis

BACKGROUND

Anastomotic leak is one of the most feared complications of colorectal surgery, and probably linked to poor blood supply to the anastomotic site. Several technologies have been described for intraoperative assessment of bowel perfusion. This systematic review and meta-analysis aimed to evaluate the most frequently used bowel perfusion assessment modalities in elective colorectal procedures, and to assess their associated risk of anastomotic leak. Technologies included indocyanine green fluorescence angiography, diffuse reflectance spectroscopy, laser speckle contrast imaging, and hyperspectral imaging.

METHODS

The review was preregistered with PROSPERO (CRD42021297299). A comprehensive literature search was performed using Embase, MEDLINE, Cochrane Library, Scopus, and Web of Science. The final search was undertaken on 29 July 2022. Data were extracted by two reviewers and the MINORS criteria were applied to assess the risk of bias.

RESULTS

Some 66 eligible studies involving 11 560 participants were included. Indocyanine green fluorescence angiography was most used with 10 789 participants, followed by diffuse reflectance spectroscopy with 321, hyperspectral imaging with 265, and laser speckle contrast imaging with 185. In the meta-analysis, the total pooled effect of an intervention on anastomotic leak was 0.05 (95 per cent c.i. 0.04 to 0.07) in comparison with 0.10 (0.08 to 0.12) without. Use of indocyanine green fluorescence angiography, hyperspectral imaging, or laser speckle contrast imaging was associated with a significant reduction in anastomotic leak.

CONCLUSION

Bowel perfusion assessment reduced the incidence of anastomotic leak, with intraoperative indocyanine green fluorescence angiography, hyperspectral imaging, and laser speckle contrast imaging all demonstrating comparable results.

Association of Preoperative High-Intensity Interval Training With Cardiorespiratory Fitness and Postoperative Outcomes Among Adults Undergoing Major Surgery: A Systematic Review and Meta-Analysis

Importance

Preoperative high-intensity interval training (HIIT) is associated with improved cardiorespiratory fitness (CRF) and may improve surgical outcomes.

Objective

To summarize data from studies comparing the association of preoperative HIIT vs standard hospital care with preoperative CRF and postoperative outcomes.

Data Sources

Data sources included Medline, Embase, Cochrane Central Register of Controlled Trials Library, and Scopus databases with no language constraints, including abstracts and articles published before May 2023.

Study Selection

The databases were searched for randomized clinical trials and prospective cohort studies with HIIT protocols in adult patients undergoing major surgery. Thirty-four of 589 screened studies met initial selection criteria.

Data Extraction and Synthesis

A meta-analysis was performed according to Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Data were extracted by multiple independent observers and pooled in a random-effects model.

Main Outcomes and Measures

The primary outcome was change in CRF, as measured by either peak oxygen consumption (V̇o2 peak) or 6-Minute Walk Test (6MWT) distance. Secondary outcomes included postoperative complications; hospital length of stay (LOS); and changes in quality of life, anaerobic threshold, and peak power output.

Results

Twelve eligible studies including 832 patients were identified. Pooled results indicated several positive associations for HIIT when compared with standard care either on CRF (V̇o2 peak, 6MWT, anaerobic threshold, or peak power output) or postoperative outcomes (complications, LOS, quality of life), although there was significant heterogeneity in study results. In 8 studies including 627 patients, there was moderate-quality evidence of significant improvement in V̇o2 peak (cumulative mean difference, 2.59 mL/kg/min; 95% CI, 1.52-3.65 mL/kg/min; P < .001). In 8 studies including 770 patients, there was moderate-quality evidence of a significant reduction in complications (odds ratio, 0.44; 95% CI, 0.32-0.60; P < .001). There was no evidence that HIIT differed from standard care in hospital LOS (cumulative mean difference, -3.06 days; 95% CI, -6.41 to 0.29 days; P = .07). The analysis showed a high degree of heterogeneity in study outcomes and an overall low risk of bias.

Conclusions and Relevance

The results of this meta-analysis suggest that preoperative HIIT may be beneficial for surgical populations through the improvement of exercise capacity and reduced postoperative complications. These findings support including HIIT in prehabilitation programs before major surgery. The high degree of heterogeneity in both exercise protocols and study results supports the need for further prospective, well-designed studies.

Impairment of Mesenteric Perfusion as a Marker of Major Bleeding in Trauma Patients

The majority of potentially preventable mortality in trauma patients is related to bleeding; therefore, early recognition and effective treatment of hemorrhagic shock impose a cardinal challenge for trauma teams worldwide. The reduction in mesenteric perfusion (MP) is among the first compensatory responses to blood loss; however, there is no adequate tool for splanchnic hemodynamic monitoring in emergency patient care. In this narrative review, (i) methods based on flowmetry, CT imaging, video microscopy (VM), measurement of laboratory markers, spectroscopy, and tissue capnometry were critically analyzed with respect to their accessibility, and applicability, sensitivity, and specificity. (ii) Then, we demonstrated that derangement of MP is a promising diagnostic indicator of blood loss. (iii) Finally, we discussed a new diagnostic method for the evaluation of hemorrhage based on exhaled methane (CH₄) measurement. Conclusions: Monitoring the MP is a feasible option for the evaluation of blood loss. There are a wide range of experimentally used methodologies; however, due to their practical limitations, only a fraction of them could be integrated into routine emergency trauma care. According to our comprehensive review, breath analysis, including exhaled CH₄ measurement, would provide the possibility for continuous, non-invasive monitoring of blood loss.

Real-time Indocyanine Green Fluorescence Technique Reduces Anastomotic Leakage in Bilioenteric Anastomosis: A Case Report and literature review

BACKGROUND

Anastomotic leakage is a serious complication that can occur in bilioenteric anastomosis surgery, leading to significant morbidity and mortality. Currently, practitioners rely on subjective measures to determine anastomotic perfusion and mechanical integrity, which have limitations. The use of indocyanine green fluorescence technology has become increasingly widespread in clinical practice, especially in gastrointestinal-related surgery. This technique has a unique role in evaluating the blood perfusion of anastomoses and reducing the incidence of anastomotic leakage. However, there have been no reports of its use in bilioenteric anastomosis surgery. Further research is needed to investigate the potential benefits of indocyanine green fluorescence technology in improving outcomes and reducing complications in this type of surgery.

CASE SUMMARY

a 50-year-old female patient underwent total laparoscopic radical resection of cholangiocarcinoma. During the surgery, indocyanine green fluorescence technology was used to complete the biliary intestinal anastomosis under full visual and dynamic monitoring. The patient recovered well after the operation without experiencing biliary leakage or other complications.

CONCLUSION

The present case study underscores the potential advantages associated with the incorporation of intraoperative real-time indocyanine green (ICG) technology in bilioenteric anastomosis surgery. By facilitating enhanced visualization and assessment of anastomotic perfusion and mechanical stability, this state-of-the-art technique may help mitigate the occurrence of anastomotic leaks while simultaneously improving patient outcomes. Notably, intravenous administration of ICG at a dose of 2.5 mg/kg, administered 24 hours prior to surgery, has been found to yield optimal visualization outcomes.

The role of intraoperative hyperspectral imaging (HSI) in colon interposition after esophagectomy

BACKGROUND

Colon conduit is an alternative approach to reconstructing the alimentary tract after esophagectomy. Hyperspectral imaging (HSI) has been demonstrated to be effective for evaluating the perfusion of gastric conduits, but not colon conduits. This is the first study to describe this new tool addressing image-guided surgery and supporting esophageal surgeons to select the optimal colon segment for the conduit and anastomotic site intraoperatively.

PATIENTS AND METHODS

Of 10 patients, eight who underwent reconstruction with a long-segment colon conduit after esophagectomy between 01/05/2018 and 01/04/2022 were included in this study. HSI was recorded at the root and tip of the colon conduit after clamping the middle colic vessels, allowing us to evaluate the perfusion and appropriate part of the colon segment.

RESULTS

Anastomotic leak (AL) was detected in only one (12.5%) of all the enrolled patients (n = 8). None of the patients developed conduit necrosis. Only one patient required re-anastomosis on postoperative day 4. No patient needed conduit removal, esophageal diversion, or stent placement. There was a change in the anastomosis site to proximal in two patients intraoperatively. There was no need to change the side of colon conduit intraoperatively in any patient.

CONCLUSION

HSI is a promising and novel intraoperative imaging tool to objectively assess the perfusion of the colon conduit. It helps the surgeon to define the best perfused anastomosis site and the side of colon conduit in this type of operation.

Feasibility and comparison of laparoscopic laser speckle contrast imaging to near-infrared display of indocyanine green in intraoperative tissue blood flow/tissue perfusion in preclinical porcine models

OBJECTIVE

To determine if laser speckle contrast imaging (LSCI) mitigates variations and subjectivity in the use and interpretation of indocyanine green (ICG) fluorescence in the current visualization paradigm of real-time intraoperative tissue blood flow/perfusion in clinically relevant scenarios.

METHODS

De novo laparoscopic imaging form-factor detecting real-time blood flow using LSCI and blood volume by near-infrared fluorescence (NIRF) of ICG was compared to ICG NIRF alone, for dye-less real-time visualization of tissue blood flow/perfusion. Experienced surgeons examined LSCI and ICG in segmentally devascularized intestine, partial gastrectomy, and the renal hilum across six porcine models. Precision and accuracy of identifying demarcating lines of ischemia/perfusion in tissues were determined in blinded subjects with varying levels of surgical experience.

RESULTS

Unlike ICG, LSCI perfusion detection was real time (latency < 150 ms: p < 0.01), repeatable and on-demand without fluorophore injection. Operating surgeons (n = 6) precisely and accurately identified concordant demarcating lines in white light, LSCI, and ICG modes immediately. Blinded subjects (n = 21) demonstrated similar spatial-temporal precision and accuracy with all three modes ≤ 2 min after ICG injection, and discordance in ICG mode at ≥ 5 min in devascularized small intestine (p < 0.0001) and in partial gastrectomy (p < 0.0001).

CONCLUSIONS

Combining LSCI for near real-time blood flow detection with ICG fluorescence for blood volume detection significantly improves precision and accuracy of perfusion detection in tissue locations over time, in real time, and repeatably on-demand than ICG alone.

Anastomotic perfusion assessment with indocyanine green in robot-assisted low-anterior resection, a multicenter study of interobserver variation

BACKGROUND

Securing sufficient blood perfusion to the anastomotic area after low-anterior resection is a crucial factor in preventing anastomotic leakage (AL). Intra-operative indocyanine green fluorescent imaging (ICG-FI) has been suggested as a tool to assess perfusion. However, knowledge of inter-observer variation among surgeons in the interpretation of ICG-FI is sparse. Our primary objective was to evaluate inter-observer variation among surgeons in the interpretation of bowel blood-perfusion assessed visually by ICG-FI. Our secondary objective was to compare the results both from the visual assessment of ICG and from computer-based quantitative analyses of ICG-FI between patients with and without the development of AL.

METHOD

A multicenter study, including patients undergoing robot-assisted low anterior resection with stapled anastomosis. ICG-FI was evaluated visually by the surgeon intra-operatively. Postoperatively, recorded videos were anonymized and exchanged between centers for inter-observer evaluation. Time to visibility (TTV), time to maximum visibility (TMV), and time to wash-out (TWO) were visually assessed. In addition, the ICG-FI video-recordings were analyzed using validated pixel analysis software to quantify blood perfusion.

RESULTS

Fifty-five patients were included, and five developed clinical AL. Bland-Altman plots (BA plots) demonstrated wide inter-observer variation for visually assessed fluorescence on all parameters (TTV, TMV, and TWO). Comparing leak-group with no-leak group, we found no significant differences for TTV: Hazard Ratio; HR = 0.82 (CI 0.32; 2.08), TMV: HR = 0.62 (CI 0.24; 1.59), or TWO: HR = 1.11 (CI 0.40; 3.11). In the quantitative pixel analysis, a lower slope of the fluorescence time-curve was found in patients with a subsequent leak: median 0.08 (0.07;0.10) compared with non-leak patients: median 0.13 (0.10;0.17) (p = 0.04).

CONCLUSION

The surgeon's visual assessment of the ICG-FI demonstrated wide inter-observer variation, there were no differences between patients with and without AL. However, quantitative pixel analysis showed a significant difference between groups.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04766060.

[ICG angiography in prevention of colorectal anastomotic leakage]

OBJECTIVE

To evaluate the effectiveness of indocyanine green fluorescence angiography in assessment of colorectal anastomosis perfusion.

MATERIAL AND METHODS

A prospective single-center non-randomized comparative study included 85 patients with rectum and sigmoid colon cancer between September 2019 and March 2023. In the main group (n=41), we intraoperatively injected indocyanine green (ICG) IV to assess perfusion in the near infrared spectrum. In the control group (n=44), the same interventions were performed without ICG.

RESULTS

In the main group, anterior resection of the rectum was performed in 23 (56.1%) patients with neoplasms of distal sigmoid colon and rectosigmoid tumors. Low anterior resection was performed in 18 (43.9%) cases. In the control group, the same procedures were carried out in 24 (54.5%) and 20 (45.5%) patients, respectively. After mobilization of the colon and ICG injection, we corrected resection line in 4 cases. As soon as anastomosis was formed and blood supply was controlled by ICG fluorescence angiography, we performed a water-bubble test to detect anastomotic leakage. Positive tests were detected in 4 (9.8%) and 5 (11.4%) patients of both groups, respectively. Postoperative complications occurred in 10 (24.4%) and 11 (27.3%) patients, respectively (p=0.94). Anastomosis failure was found in 1 and 7 patients, respectively. Anastomotic leakage grade «B» was significantly more common in the control group (2.4 and 13.6%, respectively, p=0.06). Anastomotic leaks were absent in all 4 patients who underwent resection level adjustment after intraoperative ICG angiography.

CONCLUSION

Fluorescent luminescence will qualitatively improve intraoperative diagnosis of hypoperfusion of resection edges. Undoubtedly, this will reduce the incidence of colorectal anastomotic leaks caused by ischemia of large bowel wall.

The Colorectal Anastomosis: A Timeless Challenge

Colorectal anastomosis is a sophisticated problem that demands an elaborate discussion and an elegant solution. "Those who forget the past are condemned to repeat it." George Santayana, Life of Reason , 1905.

Unsupervised and quantitative intestinal ischemia detection using conditional adversarial network in multimodal optical imaging

Purpose

Intraoperative evaluation of bowel perfusion is currently dependent upon subjective assessment. Thus, quantitative and objective methods of bowel viability in intestinal anastomosis are scarce. To address this clinical need, a conditional adversarial network is used to analyze the data from laser speckle contrast imaging (LSCI) paired with a visible-light camera to identify abnormal tissue perfusion regions.

Approach

Our vision platform was based on a dual-modality bench-top imaging system with red-green-blue (RGB) and dye-free LSCI channels. Swine model studies were conducted to collect data on bowel mesenteric vascular structures with normal/abnormal microvascular perfusion to construct the control or experimental group. Subsequently, a deep-learning model based on a conditional generative adversarial network (cGAN) was utilized to perform dual-modality image alignment and learn the distribution of normal datasets for training. Thereafter, abnormal datasets were fed into the predictive model for testing. Ischemic bowel regions could be detected by monitoring the erroneous reconstruction from the latent space. The main advantage is that it is unsupervised and does not require subjective manual annotations. Compared with the conventional qualitative LSCI technique, it provides well-defined segmentation results for different levels of ischemia.

Results

We demonstrated that our model could accurately segment the ischemic intestine images, with a Dice coefficient and accuracy of 90.77% and 93.06%, respectively, in 2560 RGB/LSCI image pairs. The ground truth was labeled by multiple and independent estimations, combining the surgeons' annotations with fastest gradient descent in suspicious areas of vascular images. The total processing time was 0.05 s for an image size of 256 × 256 .

Conclusions

The proposed cGAN can provide pixel-wise and dye-free quantitative analysis of intestinal perfusion, which is an ideal supplement to the traditional LSCI technique. It has potential to help surgeons increase the accuracy of intraoperative diagnosis and improve clinical outcomes of mesenteric ischemia and other gastrointestinal surgeries.

Intraoperative Patterns of Gastric Microperfusion During Laparoscopic Roux-en-Y Gastric Bypass

INTRODUCTION

Visible light spectroscopy (VLS) represents a sensitive, non-invasive method to quantify tissue oxygen levels and detect hypoxemia. The aim of this study was to assess the microperfusion patterns of the gastric pouch during laparoscopic Roux-en-Y gastric bypass (LRYGB) using the VLS technique.

METHODS

Twenty patients were enrolled. Tissue oxygenation (StO2%) measurements were performed at three different localizations of the gastric wall, prior and after the creation of the gastric pouch, and after the creation of the gastro-jejunostomy.

RESULTS

Prior to the creation of the gastric pouch, the lowest StO2% levels were observed at the level of the distal esophagus with a median StO2% of 43 (IQR 40.8-49.5). After the creation of the gastric pouch and after the creation of the gastro-jejunostomy, the lowest StO2% levels were recorded at the level of the His angle with median values of 29% (IQR 20-38.5) and 34.5% (IQR 19-39), respectively. The highest mean StO2 reduction was recorded at the level of the His angle after the creation of the gastric pouch, and it was 18.3% (SD ± 18.1%, p < 0.001). A reduction of StO2% was recorded at all localizations after the formation of the gastro-jejunostomy compared to the beginning of the operation, but the mean differences of the StO2% levels were statistically significant only at the resection line of the pouch and at the His angle (p = 0.044 and p < 0.001, respectively).

CONCLUSION

Gastric pouch demonstrates reduction of StO2% during LRYGB. VLS is a useful technique to assess microperfusion patterns of the stomach during LRYGB.

Endoscopic vacuum therapy and early surgical closure after pelvic anastomotic leak: meta-analysis of bowel continuity rates

BACKGROUND

Endoscopic vacuum therapy (EVT) with or without early surgical closure (ESC) is considered an effective option in the management of pelvic anastomotic leakage. This meta-analysis evaluated the effectiveness of EVT in terms of stoma reversal rate and the added value of ESC.

METHODS

A systematic search of PubMed, MEDLINE, and the Cochrane Library was conducted in November 2021 to identify articles on EVT in adult patients with pelvic anastomotic leakage. The primary outcome was restored continuity rate. Following PRISMA guidelines, a meta-analysis was undertaken using a random-effects model.

RESULTS

Twenty-nine studies were included, accounting for 827 patients with leakage who underwent EVT. There was large heterogeneity between studies in design and reported outcomes, and a high risk of bias. The overall weighted mean restored continuity rate was 66.8 (95 per cent c.i. 58.8 to 73.9) per cent. In patients undergoing EVT with ESC, the calculated restored continuity rate was 82 per cent (95 per cent c.i. 50.1 to 95.4) as compared to 64.7 per cent (95 per cent c.i. 55.7 to 72.7) after EVT without ESC. The mean number of sponge exchanges was 4 (95 per cent c.i. 2.7 to 4.6) and 9.8 (95 per cent c.i. 7.3 to 12.3), respectively. Sensitivity analysis showed a restored continuity rate of 81 per cent (95 per cent c.i. 55.8 to 99.5) for benign disease, 69.0 per cent (95 per cent c.i. 57.3 to 78.7) for colorectal cancer, and 65 per cent (95 per cent c.i. 48.8 to 79.1) if neoadjuvant radiotherapy was given.

CONCLUSION

EVT is associated with satisfactory stoma reversal rates that may be improved if it is combined with ESC.

Risk factors for short-term complications graded by Clavien-Dindo after transanal endorectal pull-through in patients with Hirschsprung disease

BACKGROUND

Transanal endorectal pull-through (TERPT) is a common surgical procedure in Hirschsprung disease (HD). Aim of this study was to gain insight in the prevalence and severity of postoperative complications within 30-days after TERPT and to identify patient and perioperative characteristics, associated with the development of short-term postoperative complications.

METHODS

This study retrospectively analyzed data of children with HD and treated with TERPT in our center between 2005 and 2020. Complications emerging within 30-days after surgery were assessed using Clavien-Dindo (CD). Patient and perioperative characteristic as predictor of a complication were tested using (multivariable) logistic regression analysis.

RESULTS

Twenty-two of 106 (21%) included patients (17 transanal only; 77 laparoscopic-assisted; 12 laparotomy-assisted) developed 35 complications, including two patients (1.8%) that deceased. We suspect postoperative rectal irrigation leading to perforation as cause of death in both patients. Six patients (6%) had a minor (CD<3) and 16 patients (15%) a major (CD≥3) complication. Anastomotic leakage (n = 4, 11%), abdominal abscess (n = 3, 9%) and anastomotic stricture (n = 3,9%) occurred most frequently. Predictive factors for developing a complication were older age at time of surgery (OR 1.03 1.00-1.01, p = 0.041), laparotomy-assisted surgery (OR 12.65, CI 1.712-93.07, p = 0.013) and long-segment HD (OR 4.09 CI 1.09-15.39, p = 0.037).

CONCLUSIONS

We found a CD-graded short-term postoperative complication rate of 21% following TERPT, reporting anastomotic complications most frequently. In patients at risk a diverting stoma should be considered. We suspect postoperative rectal irrigation being the cause of two lethal perforations. Therefore, we recommend to place a rectal transanastomotic tube in all patients receiving TERPT.

LEVEL OF EVIDENCE

Level III.

Intraoperative Colonoscopy in Laparoscopic Rectal Cancer Surgery Reduces Anastomotic Leakage

Objectives:

Anastomotic leakage (AL) is the most severe complication of colorectal surgery and is a frequent cause of postoperative mortality. This study aimed to identify the risk factors for AL, including the type of air leak test (ALT) performed, in patients undergoing laparoscopic colorectal cancer surgery.

Methods:

This study involved a retrospective review of 201 patients who underwent elective laparoscopic procedures using circular stapled anastomosis for colorectal cancer between January 2015 and December 2020 at Kyorin University Hospital, Tokyo, Japan. In all cases, the distance from the anal verge to the anastomotic site was within 15 cm.

Results:

Overall, AL was observed in 16 patients (8.0%). Univariate analysis revealed that the risk factors for AL included diabetes (P = 0.068), tumor location (P = 0.049), level of anastomosis (P = 0.002), number of linear stapler firings (P = 0.007), and intraoperative colonoscopy (IOCS; P = 0.069). Multivariate analysis revealed that the level of anastomosis (P = 0.029) and IOCS (P = 0.039) were significant and independent risk factors for AL. One of the 107 patients undergoing ALT without IOCS and 3 of the 94 patients undergoing ALT with IOCS were proven to be positive for air leak. However, these four patients underwent additional suturing intraoperatively and developed no AL following surgery.

Conclusions:

This study identified the level of anastomosis and ALT with IOCS as predictors for AL. The results of our study indicate that ALT with IOCS may be more effective than ALT without IOCS in the diagnosis and prevention of AL.

Deep Learning to Measure the Intensity of Indocyanine Green in Endometriosis Surgeries with Intestinal Resection

Endometriosis is a gynecological pathology that affects between 6 and 15% of women of childbearing age. One of the manifestations is intestinal deep infiltrating endometriosis. This condition may force patients to resort to surgical treatment, often ending in resection. The level of blood perfusion at the anastomosis is crucial for its outcome, for this reason, indocyanine green (ICG), a fluorochrome that green stains the structures where it is present, is injected during surgery. This study proposes a novel method based on deep learning algorithms for quantifying the level of blood perfusion in anastomosis. Firstly, with a deep learning algorithm based on the U-Net, models capable of automatically segmenting the intestine from the surgical videos were generated. Secondly, blood perfusion level, from the already segmented video frames, was quantified. The frames were characterized using textures, precisely nine first- and second-order statistics, and then two experiments were carried out. In the first experiment, the differences in the perfusion between the two-anastomosis parts were determined, and in the second, it was verified that the ICG variation could be captured through the textures. The best model when segmenting has an accuracy of 0.92 and a dice coefficient of 0.96. It is concluded that segmentation of the bowel using the U-Net was successful, and the textures are appropriate descriptors for characterization of the blood perfusion in the images where ICG is present. This might help to predict whether postoperative complications will occur during surgery, enabling clinicians to act on this information.

Prediction of anastomotic leakage after left-sided colorectal cancer surgery: a pilot study utilizing quantitative near-infrared spectroscopy

BACKGROUND

Anastomotic leakage (AL) occurs with some frequency in all types of colorectal cancer surgery and is associated with increased morbidity, mortality and recurrence rates. Complications might be prevented by monitoring intra-operative bowel perfusion at the anastomotic site. A pilot study concerning the objective and quantitative measurement of tissue perfusion by monitoring regional tissue saturation of oxygen (rSO₂) was conducted, using the In Vivo Optical Spectroscopy (INVOS™) system (Medtronic, Minneapolis, MN, USA).

METHODS

This study evaluated the ability of the INVOS™ system to predict AL after left-sided colorectal cancer surgery. rSO₂ measurements of the oral side of the site of bowel anastomosis were taken before anastomosis in 73 patients. Clinical factors, including rSO₂, were analyzed to identify risk factors for AL.

RESULTS

Among 73 patients, 6 (8.2%) experienced AL. The rSO₂ values of the oral anastomotic site were significantly lower in AL patients than in non-AL patients. In the multivariate analysis, the rSO₂ value of the oral anastomotic site was an independent risk factor for AL.

CONCLUSION

Monitoring the rSO₂ at the anastomotic site enabled the prediction of AL. A prospective study to evaluate the efficacy of the INVOS™ system for monitoring intestinal rSO₂ is in progress.

Prehabilitation, enhanced recovery after surgery, or both? A narrative review

This narrative review presents a biological rationale and evidence to describe how the preoperative condition of the patient contributes to postoperative morbidity. Any preoperative condition that prevents a patient from tolerating the physiological stress of surgery (e.g. poor cardiopulmonary reserve, sarcopaenia), impairs the stress response (e.g. malnutrition, frailty), and/or augments the catabolic response to stress (e.g. insulin resistance) is a risk factor for poor surgical outcomes. Prehabilitation interventions that include exercise, nutrition, and psychosocial components can be applied before surgery to strengthen physiological reserve and enhance functional capacity, which, in turn, supports recovery through attaining surgical resilience. Prehabilitation complements Enhanced Recovery After Surgery (ERAS) care to achieve optimal patient outcomes because recovery is not a passive process and it begins preoperatively.

High Ligation of the Inferior Mesenteric Artery Induces Hypoperfusion of the Sigmoid Colon Stump During Anterior Resection

Background: Anastomotic leakage (AL) after colorectal surgery is associated with insufficient vascular perfusion of the anastomotic ends. This study aimed to evaluate the effect of high vs. low ligation of the ileocolic artery and inferior mesenteric artery, respectively, on the vascular perfusion of the bowel stumps during ileocecal resection (ICR) and anterior rectal resection (AR). Methods: We retrospectively evaluated patients who underwent ICR or AR between 2016 and 2020. Real-time indocyanine green fluorescence angiography was performed to measure the fluorescence time (FT) as a marker of the blood flow in the proximal and distal stumps before anastomosis. Results: Thirty-four patients with lower right-sided colon cancer underwent laparoscopic ICR. Forty-one patients with rectosigmoid colon or rectal cancer underwent robotic high AR (HAR) (n = 8), robotic low AR (LAR) (n = 6), laparoscopic HAR (n = 8), or laparoscopic LAR (n = 19). The FT was similar in the ileal and ascending colon stumps (p = 1.000) and did not differ significantly between high vs. low ligation of the ileocolic artery (p = 0.934). The FT was similar in the sigmoid colon and rectal stumps (p = 0.642), but high inferior mesenteric artery ligation significantly prolonged FT in the sigmoid colon during AR compared with low ligation (p = 0.004), indicating that the high ligation approach caused significant hypoperfusion compared with low ligation. The AL rate was similar after low vs. high ligation. Conclusions: Low vascular perfusion of the bowel stumps may not be an absolute risk factor for AL. High inferior mesenteric artery ligation could induce sigmoid colon stump hypoperfusion during anterior rectal resection.

Intraoperative colon perfusion assessment using multispectral imaging

In colorectal surgery an anastomosis performed using poorly-perfused, ischaemic bowel segments may result in a leak and consequent morbidity. Traditional measures of perfusion assessment rely on clinical judgement and are mainly subjective, based on tissue appearance, leading to variability between clinicians. This paper describes a multispectral imaging (MSI) laparoscope that can derive quantitative measures of tissue oxygen saturation (SO₂ ). The system uses a xenon surgical light source and fast filter wheel camera to capture eight narrow waveband images across the visible range in approximately 0.3 s. Spectral validation measurements were performed by imaging standardised colour tiles and comparing reflectance with ground truth spectrometer data. Tissue spectra were decomposed into individual contributions from haemoglobin, adipose tissue and scattering, using a previously-developed regression approach. Initial clinical results from seven patients undergoing colorectal surgery are presented and used to characterise measurement stability and reproducibility in vivo. Strategies to improve signal-to-noise ratio and correct for motion are described. Images of healthy bowel tissue (in vivo) indicate that baseline SO₂ is approximately 75 ± 6%. The SO₂ profile along a bowel segment following ligation of the inferior mesenteric artery (IMA) shows a decrease from the proximal to distal end. In the clinical cases shown, imaging results concurred with clinical judgements of the location of well-perfused tissue. Adipose tissue, visibly yellow in the RGB images, is shown to surround the mesentery and cover some of the serosa. SO₂ in this tissue is consistently high, with mean value of 90%. These results show that MSI is a potential intraoperative guidance tool for assessment of perfusion. Mapping of SO₂ in the colon could be used by surgeons to guide choice of transection points and ensure that well-perfused tissue is used to form an anastomosis. The observation of high mesenteric SO₂ agrees with work in the literature and warrants further exploration. Larger studies incorporating with a wider cohort of clinicians will help to provide retrospective evidence of how this imaging technique may be able to reduce inter-operator variability.

Strategy to Avoid Anastomotic Leakage in Laparoscopic Colorectal Resection Using the Indocyanine Green Fluorescence System

Purpose

Anastomotic leakage (AL) in colorectal resections is often caused by insufficient blood flow to the stump. Injecting indocyanine green can help detect blood flow intraoperatively. In this study, we evaluated our original strategy using an indocyanine green fluorescence system to avoid AL.

Methods

We retrospectively evaluated 79 patients who underwent laparoscopic colorectal resection for colon cancer using a double-stapling technique. Blood flow in oral stumps was evaluated by measuring indocyanine green fluorescence time (FT). We investigated AL cases in detail and analyzed correlations between FT and risk factors for AL.

Results

Of the 79 patients, 7 (8.9%) developed AL. We divided patients by FTs: &gt;60 seconds, 50 to 60 seconds, and &lt;50 seconds. The AL rates were FT &gt;60 seconds, 60%; FT 50 to 60 seconds, 10.3%; and FT &lt;50 seconds, 2.2%. The AL rate of high-risk cases (with more than 2 risk factors) were calculated and we made our original strategy to avoid AL as the following. Further resection or diverting stomas were needed by the FT &gt;60 seconds group, and by members of the FT 50 to 60 seconds group with ≥3 risk factors. The FT &lt;60 seconds group needed no additional management.

Conclusions

Patients with delayed FT (&gt;60 seconds, or 50–60 seconds with ≥3 risk factors) may need revision of the anastomosis (diverting stoma or additional resection) to avoid AL. Our original strategy may contribute to reduce AL in colorectal operations.

Intraoperative Control of Hemoglobin Oxygen Saturation in the Intestinal Wall during Anastomosis Surgery

During surgery for colon cancer, monitoring of the oxygen saturation of hemoglobin in the tissues under study makes it possible to assess the degree of blood supply to the anastomosis areas of the colon. Adequate blood supply in this area is decisive in terms of the consistency of the anastomosis and can significantly reduce the risk leakage of anastomosis. In this work, we propose a new approach to assessing the hemoglobin oxygen saturation based on measuring both the diffuse reflectance and transmittance spectra of the colon wall tissues. The proposed method is based on the use of two fiber-optic tools for irradiation from both sides—the intestinal lumen and the outside of the intestinal wall. The spectra are recorded from the external side. To determine the degree of hemoglobin saturation, two algorithms, both based on the Taylor series expansion of the coefficient of light attenuation by tissues, are proposed. The results of a clinical study of the proposed approach on volunteers were obtained, allowing to draw a conclusion about the applicability of the approach in a clinical setting.

Predicting intestinal viability by consecutive photoacoustic monitoring of oxygenation recovery after reperfusion in acute mesenteric ischemia in rats

The purpose was to assess whether consecutive monitoring of oxygenation by photoacoustic imaging (PAI) can objectively predict intestinal viability during surgery for acute mesenteric ischemia (AMI). PAI uses laser light to detect relative amounts of oxygenated and deoxygenated hemoglobin in intestinal tissue. In 30 rats, AMI was induced by clamping the mesenteric and marginal vessels of the ileum for 0 min in the control group, 30 min in the mild group, and 180 min in the severe group (10 rats per group). After 60 min of reperfusion, intestinal damage was evaluated pathologically. Oxygenation of the intestine was monitored throughout the procedure in real time by a commercially available PAI system and compared among the groups. All rats showed irreversible (i.e. transmucosal or transmural infarction) damage in the severe group. After reperfusion, the oxygenation in the mild group recovered immediately and was significantly higher than in the severe group at 1, 5, 10, 30, and 60 min (P = .011, 002, < .001, 001, and 001, respectively). Oxygenation showed a significant strong negative correlation with pathological severity (r_s =  − 0.7783, − 0.7806, − 0.7422, − 0.7728, and − 0.7704, respectively). In conclusion, PAI could objectively predict irreversible ischemic damage immediately after reperfusion, which potentially prevents inadequate surgery.

From clinical guidelines to practice: The nutrition elements for enhancing recovery after colorectal surgery

The Enhanced Recovery After Surgery (ERAS) Care System improves patient outcomes. The ERAS Protocol describes multimodal, evidence-based processes that are bundled into >20 care elements, and the ERAS Implementation Program provides strategies to guide the successful adoption of the care elements. Although formal training is essential to implement ERAS correctly, with this article we aim to bridge the gap between the nutritionally relevant care elements of the protocol and their implementation for colorectal surgery. This article also describes how dietitians can support optimal patient outcomes by playing an active role in implementing, monitoring, and evaluating ERAS practices.

Post-Operative Monitoring of Intestinal Tissue Oxygenation Using an Implantable Microfabricated Oxygen Sensor

Anastomotic leakage (AL) is a common and dangerous post-operative complication following intestinal resection, causing substantial morbidity and mortality. Ischaemia in the tissue surrounding the anastomosis is a major risk-factor for AL development. Continuous tissue oxygenation monitoring during the post-operative recovery period would provide early and accurate early identification of AL risk. We describe the construction and testing of a miniature implantable electrochemical oxygen sensor that addresses this need. It consisted of an array of platinum microelectrodes, microfabricated on a silicon substrate, with a poly(2-hydroxyethyl methacrylate) hydrogel membrane to protect the sensor surface. The sensor was encapsulated in a biocompatible package with a wired connection to external instrumentation. It gave a sensitive and highly linear response to variations in oxygen partial pressure in vitro, although over time its sensitivity was partially decreased by protein biofouling. Using a pre-clinical in vivo pig model, acute intestinal ischaemia was robustly and accurately detected by the sensor. Graded changes in tissue oxygenation were also measurable, with relative differences detected more accurately than absolute differences. Finally, we demonstrated its suitability for continuous monitoring of tissue oxygenation at a colorectal anastomosis over a period of at least 45 h. This study provides evidence to support the development and use of implantable electrochemical oxygen sensors for post-operative monitoring of anastomosis oxygenation.

Predictive and Diagnostic Biomarkers of Anastomotic Leakage: A Precision Medicine Approach for Colorectal Cancer Patients

Development of an anastomotic leak (AL) following intestinal surgery for the treatment of colorectal cancers is a life-threatening complication. Failure of the anastomosis to heal correctly can lead to contamination of the abdomen with intestinal contents and the development of peritonitis. The additional care that these patients require is associated with longer hospitalisation stays and increased economic costs. Patients also have higher morbidity and mortality rates and poorer oncological prognosis. Unfortunately, current practices for AL diagnosis are non-specific, which may delay diagnosis and have a negative impact on patient outcome. To overcome these issues, research is continuing to identify AL diagnostic or predictive biomarkers. In this review, we highlight promising candidate biomarkers including ischaemic metabolites, inflammatory markers and bacteria. Although research has focused on the use of blood or peritoneal fluid samples, we describe the use of implantable medical devices that have been designed to measure biomarkers in peri-anastomotic tissue. Biomarkers that can be used in conjunction with clinical status, routine haematological and biochemical analysis and imaging have the potential to help to deliver a precision medicine package that could significantly enhance a patient's post-operative care and improve outcomes. Although no AL biomarker has yet been validated in large-scale clinical trials, there is confidence that personalised medicine, through biomarker analysis, could be realised for colorectal cancer intestinal resection and anastomosis patients in the years to come.

Intestinal hypoperfusion in patients with Crohn's disease revealed by intraoperative indocyanine green fluorescence imaging

Background

Anastomotic leakage has been reported as an independent risk factor for surgical recurrence at the anastomotic site in patients with Crohn's disease. An inadequate blood supply may contribute to this leakage. Real-time indocyanine green angiography has been useful for confirming vascular perfusion of the intestines. The aim of this study was to evaluate the use of intraoperative indocyanine green angiography to detect vascular perfusion of the intestines during ileocaecal resection in patients with Crohn's disease and colon cancer.

Materials and methods

We retrospectively evaluated the medical records of 26 consecutive patients with colon cancer arising in the caecum or ascending colon and 3 consecutive patients with Crohn's disease without a history of disease-related surgery. The patients in the 2 cohorts had undergone ileocaecal resection at Tokushima University Hospital between January 2018 and January 2021. After ileocaecal resection, blood flow was evaluated in ileal (oral) and colon (anal) stapled stumps by indocyanine green fluorescence angiography. The fluorescence time was defined as the time from indocyanine green injection and flush of the injection route to the point when the stump showed the strongest fluorescent signal in the monitor.

Results

The fluorescence time for the ileal and colon stumps in patients with Crohn's disease was 43.3 ± 8.8 s each and was significantly longer than the fluorescence time in the patients with colon cancer (29.4 ± 6.5 s and 29.6 ± 6.8 s, respectively) (P < 0.05).

Conclusion

Intraoperative indocyanine green fluorescence imaging is safe and reproducible for assessing intestinal perfusion prior to anastomosis in patients with colon cancer and Crohn's disease.

•

Low blood supply increases leakage and surgical recurrence in Crohn's disease.

•

Indocyanine green angiography is useful for evaluating the intestinal blood supply.

•

Blood supply at anastomotic sites was lower in Crohn's disease than colon cancer.

Dynamic Serosal Perfusion Assessment during Colorectal Resection Using Visible Light Spectroscopy

INTRODUCTION

Anastomotic leakage (AL) in colorectal surgery occurs with an incidence of up to 20%. Bowel perfusion is deemed to be one of the most important factors for anastomotic healing. However, not much is known about its variability during colorectal surgery and its impact on the outcome. Therefore, this study aims to evaluate serosal oxygen saturation patterns during colorectal resections with visible light spectroscopy (VLS).

MATERIALS AND METHODS

Bowel perfusion in patients undergoing left-sided colorectal resections was assessed at different timepoints during surgery using VLS on the colonic serosa. The primary outcome parameter was serosal oxygen saturation (StO2) at the anastomosis during different timepoints of surgery.

RESULTS

We included 50 patients who underwent colorectal resection for bowel cancer (58%) and diverticular disease (34%). StO2 at the proximal site of the anastomosis increased significantly throughout the surgery (mean difference 3.61%; 95% CI -6.22 to -1.00; p = 0.008). However, aberrancy from this identified perfusion pattern had no impact on the postoperative outcome.

CONCLUSION

During colorectal resections, we could demonstrate an increase of the colonic StO2 throughout surgery. Appearance of AL was not associated with lower StO2, underlining the multifactorial genesis of developing AL.

Analysis of Cumulative Fluid Balance Impact on the Stability of Gastrointestinal Tract Anastomosis

Anastomotic leakage is a serious postoperative complication following a low anterior resection of rectum. Current research in colorectal surgery focuses on searching for techniques which could minimize the risk of leakage. The main objective of this study was to evaluate the impact of cumulative fluid balance on microcirculatory changes at the anastomotic site.This experimental study used 15 domestic pigs; all of the animals underwent rectal resection. Then the animals were divided into three groups and received IV crystalloids at various rates, i.e. 5 ml/kg/h; 10 ml/kg/h; and 20 ml/kg/h. Large bowel micro-perfusion was measured using laser Doppler flowmetry during and following the surgical procedure.The experiments were successfully performed in all 15 cases. No animal died during the procedure or during the follow-up. We found no differences in micro-perfusion of the bowel between the experimental groups during the surgical procedure and during the follow-up period after the surgery. A significant decrease in micro-perfusion was observed after the transection of the inferior mesenteric artery in all the groups; again, no differences between the groups were observed.We did not confirm the original hypothesis that excessive load of IV crystalloids during the surgery would have a negative effect on bowel micro-perfusion and thus a negative effect on the healing of the anastomosis. However, laser Doppler flowmetry was found to have high accuracy in measuring tissue microcirculation and has the potential to be used in clinical practice.

Intraoperative Thermal Imaging for Evaluating Blood Perfusion During Laparoscopic Colorectal Surgery

BACKGROUND

Anastomotic leakage is a feared complication of anterior resection for rectal cancer. Among the various factors reported to be involved in the occurrence of anastomotic leakage, blood perfusion of the remnant intestine is one of the most important. Recently, the usefulness of evaluating blood perfusion using indocyanine green (ICG) has been reported. We therefore aimed to show that measuring intestinal temperature using thermography is useful for evaluating blood perfusion. The authors also investigated the relation between intestinal temperatures and the ICG fluorescence time (FT).

MATERIALS AND METHODS

Altogether, 45 patients who underwent laparoscopic anterior resection for rectal cancer between July 2017 and September 2018 were enrolled in this study. ICG FT and intestinal temperature were measured after the mesenteric dissection.

RESULT

The temperature boundary could be easily identified using thermographic images. The temperature of the residual intestinal tract was significantly higher than that of the resected intestinal tract at the planned separation line (29.9 vs. 27.3°C). In addition, there was an inverse correlation between the ICG FT and the temperature of the residual intestine.

CONCLUSION

Intestinal temperature measurement through thermography is a useful new tool for evaluating intestinal blood perfusion.

The sigmoidea ima artery: A player in colonic ischemia?

INTRODUCTION

The sigmoidea ima artery is defined as the lowest sigmoid artery, which forms the distal end of the marginal artery by linking with the superior rectal artery. It supplies the rectosigmoid junction, which is a critical area for ischemia. The aim of the present study was to delineate the area supplied by the inferior mesenteric artery with special consideration of the sigmoidea ima artery.

MATERIALS AND METHODS

The inferior mesenteric artery was dissected from its origin to the bifurcation of the superior rectal artery in 30 cadavers (15 male, 15 female). Vessel length and distance to the promontory were measured for each branch.

RESULTS

There were two manifestations of the sigmoidea ima artery, irrespective of the branching pattern of the inferior mesenteric artery. It originated below the promontory in 25 cases (83.3%) and above it in three (10%). It did not derive from the superior rectal artery in two cases (6.7%). In these 16.7%, the marginal artery was absent near the rectosigmoid junction.

CONCLUSIONS

We suggest the terms "arteria sigmoidea ima pelvina" and "arteria sigmoidea ima abdominalis" for the two variants. The terms "arteria marginalis pelvina" and "arteria marginalis abdominalis" could be applied in clinical practice. An abdominal marginal artery could be considered a risk factor for colonic ischemia in colorectal resections and abdominal aortic aneurysm repair. Both variants should be considered when pre- and intra-operative perfusion measurements are interpreted.

Fluorescence Image-Based Evaluation of Gastric Tube Perfusion during Esophagogastrostomy

During esophagectomy and esophagogastrostomy, the prediction of anastomotic leakage relies on the operating surgeon's tactile or visual diagnosis. Therefore, anastomotic leaks are relatively unpredictable, and new intraoperative evaluation methods or tools are essential. A fluorescence imaging system enables visualization over a wide region of interest, and provides intuitive information on perfusion intraoperatively. Surgeons can choose the best anastomotic site of the gastric tube based on fluorescence images in real time during surgery. This technology provides better surgical outcomes when used with an optimal injection dose and timing of indocyanine green.

Noninvasive assessment of bowel blood perfusion using intraoperative laser speckle flowgraphy

PURPOSE

Laser speckle flowgraphy (LSFG) is a noninvasive method for quantitative evaluation of blood flow using the mean blur rate (MBR) as the blood flow index. We investigated whether LSFG can intraoperatively detect the demarcation line after vessel dissection and reduce the incidence of anastomotic leakage (AL).

METHODS

This study included 36 patients who underwent left-sided colorectal surgery. First, we compared the demarcation line (determined by LSFG) with the transection line (TL) at which the marginal vessels were divided. We then measured the MBR on both sides of the TL to determine where the MBR changed significantly. We investigated the presence or absence of significant differences between the MBR on the proximal side and that on the distal side of the TL. Finally, we retrospectively compared the patient characteristics and AL rates in the LSFG group (n = 36) and control group (n = 87).

RESULTS

In total, 58.3% (21/36) of the demarcation lines determined by LSFG matched the TL. The median distance between the demarcation line determined by LSFG and the TL was 0.0 mm (0.0-12.1 mm). The MBR sharply decreased at the TL in 80.6% (29/36) of cases. The median MBR was significantly lower on the distal than proximal side. The AL rate was not significantly lower in the LSFG group than in the control group.

CONCLUSION

LSFG accurately detected the demarcation line during surgery. However, LSFG did not reduce the incidence of AL.

Indocyanine green fluorescence angiography to evaluate anastomotic perfusion in colorectal surgery

BACKGROUND

The aim of this study was to evaluate the efficacy of indocyanine green (ICG) fluorescence angiography with respect to the anastomotic leakage rate for patients undergoing colorectal operations.

METHODS

This prospective cohort involved patients who underwent colorectal surgery between August 2018 and September 2019. ICG was injected after colonic transection. Vascular perfusion was observed by ICG fluorescence system before completing anastomosis. Data was compared with those by subjective visual evaluation. The primary outcome was anastomotic leakage rate within 30 days from surgery.

RESULTS

A total of 131 patients were enrolled, of which ICG was injected in 63 of them. Demographic data were similar between the two groups. There were two (3.23%) and three (4.35%) anastomotic leaks in the ICG and non-ICG group respectively (p = 1.000). Change of resection plane occurred in one patient in the ICG group. There was no ICG related toxicity or adverse events.

CONCLUSION

ICG fluorescent imaging is a feasible and safe tool to assess colonic vascularisation for patients undergoing colorectal surgery. However, it did not significantly lower the anastomotic leakage rate. ICG should not be routinely used in colorectal surgery before an available large scale randomised controlled trial to prove any clinical benefits.

A prospective trial of intraoperative tissue oxygenation measurement and its association with anastomotic leak rate after Ivor Lewis esophagectomy

Background

Anastomotic leak following Ivor Lewis esophagectomy is associated with increased morbidity/mortality and decreased survival. Tissue oxygenation at the anastomotic site may influence anastomotic leak. Methods for establishing tissue oxygenation at the anastomotic site are lacking.

Methods

Over a 2-year study period, 185 Ivor Lewis esophagectomies were performed. Study participants underwent measurement of gastric conduit tissue oxygenation at the planned anastomotic site using the wireless pulse oximetry device. Associations between anastomotic leaks or strictures and tissue oxygenation levels were analyzed using Wilcoxon rank sum test or Fisher’s exact test.

Results

Among study participants (n=114), median gastric conduit tissue oxygenation level was 92% (range, 62–100%). There were 8 (7.0%) anastomotic leaks and 3 (2.6%) strictures. Analysis of tissue oxygenation as a continuous variable showed no difference in median tissue oxygenation in patients with and without leaks (98% and 92%; P=0.2) and stricture formation (89% and 92%; P=0.6). Analysis of tissue oxygenation as a dichotomous variable found no difference in anastomotic leak rates [7.5% (n=93) in >80% vs. 0% (n=20) in ≤80%; P=0.3]. There were no significant differences in leak rates in concurrent study nonparticipants.

Conclusions

No significant association was observed between intraoperative tissue oxygenation at the anastomotic site and subsequent anastomotic leak or stricture formation among patients undergoing Ivor Lewis esophagectomy.

Quantitative fluorescence angiography versus hyperspectral imaging to assess bowel ischemia: A comparative study in enhanced reality

BACKGROUND

Fluorescence-based enhanced reality is a software that provides quantitative fluorescence angiography by computing the fluorescence intensity time-to-peak after intravenous indocyanine green. Hyperspectral imaging is a contrast-free, optical imaging modality which measures tissue oxygenation.

METHODS

In 8 pigs, an ischemic bowel segment created by dividing the arcade branches was imaged using hyperspectral imaging and fluorescence-based enhanced reality. Tissue oxygenation values were acquired through a hyperspectral imaging system. Subsequently, fluorescence angiography was performed using a near-infrared laparoscopic camera after intravenous injection of 0.2 mg/kg of indocyanine green. The time-to-peak fluorescence signal was analyzed through a proprietary software to realize a perfusion map. This was overlaid onto real-time images to obtain fluorescence-based enhanced reality. Simultaneously, 9 adjacent regions of interest were selected and superimposed onto the real-time video, thereby obtaining hyperspectral-based enhanced reality. Fluorescence-based enhanced reality and hyperspectral-based enhanced reality were superimposed allowing a comparison of both imaging modalities. Local capillary lactate levels were sampled at the regions of interest. Two prediction models using the local capillary lactate levels were extrapolated based on both imaging systems.

RESULTS

For all regions of interest, the mean local capillary lactate levels were 4.67 ± 4.34 mmol/L, the mean tissue oxygenation was 45.9 ± 18.9%, and the mean time-to-peak was 10 ± 9.4 seconds. Pearson's test between fluorescence-based enhanced reality-time-to-peak and hyperspectral imaging-tissue oxygenation at the corresponding regions of interest gave an R = -0.66 (P < .0001). The hyperspectral imaging lactate prediction model proved more accurate than the fluorescence-based enhanced reality-based model (P < .0001).

CONCLUSION

Bowel perfusion was quantified using hyperspectral imaging and fluorescence angiography. Hyperspectral imaging yielded more accurate results than fluorescence angiography. Hyperspectral-based enhanced reality may prove to be a useful, contrast-free intraoperative tool to quantify bowel ischemia.

Systematic Review on the Influence of Tissue Oxygenation on Gut Microbiota and Anastomotic Healing

BACKGROUND

Anastomotic leak rates have not improved over several decades despite improvements in surgical techniques and patient care. The gut microbiome has been implicated in the development of leaks. The exact mechanisms by which tissue oxygenation affects gut microbial composition and anastomotic healing physiology are unclear. Also, commonly used carbon dioxide (CO₂) is a known vasodilator that improves tissue oxygen tension. We performed a systematic review to determine the influence of hyperoxia, hypoxia, and hypercapnia on the gut microbiome and anastomotic healing.

METHODS

A literature search was performed in MEDLINE, EMBASE, and COCHRANE to identify studies investigating the effects of hyperoxia, hypoxia, and hypercapnia on anastomotic healing and gut microbiota published between 1998 and 2018. Two reviewers screened the articles for eligibility and quality. Fifty-three articles underwent full text review, and a narrative synthesis was undertaken.

RESULTS

Hyperoxia is associated with better anastomotic healing, increased gastrointestinal oxygen tension, and may reduce gut anaerobes. Hypoxia is associated with poor healing and increased gut anaerobes. However, it is unclear if hypoxia is the most important predictor of anastomotic leaks. Low pressure CO₂ pneumoperitoneum and mild systemic hypercapnia are both associated with increased gastrointestinal oxygen tension and may improve anastomotic healing. We found no studies which investigated the effect of hypercapnia on gut microbiota in the context of anastomotic healing.

CONCLUSIONS

Tissue oxygenation influences gut anastomotic healing, but little evidence exists to demonstrate the influence on the gut microbiome in the context of healing. Further studies are needed to determine if anastomotic microbiome changes with altered tissue oxygenation and if this affects healing and leak rates. If confirmed, altering tissue oxygenation through hyperoxia or hypercapnia could be feasible means of altering the microbiome such that anastomotic leak rates reduce.

Reducing anastomotic leak in colorectal surgery: The old dogmas and the new challenges

Anastomotic leak (AL) constitutes a significant issue in colorectal surgery, and its incidence has remained stable over the last years. The use of intra-abdominal drain or the use of mechanical bowel preparation alone have been proven to be useless in preventing AL and should be abandoned. The role or oral antibiotics preparation regimens should be clarified and compared to other routes of administration, such as the intravenous route or enema. In parallel, preoperative antibiotherapy should aim at targeting collagenase-inducing pathogens, as identified by the microbiome analysis. AL can be further reduced by fluorescence angiography, which leads to significant intraoperative changes in surgical strategies. Implementation of fluorescence angiography should be encouraged. Progress made in AL comprehension and prevention might probably allow reducing the rate of diverting stoma and conduct to a revision of its indications.

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) might increase the risk of anastomotic leakage compared to HIPEC: an experimental study

BACKGROUND

Pressurized intraperitoneal aerosol chemotherapy (PIPAC) and hyperthermic intraperitoneal chemotherapy (HIPEC) are technics proposed to treat patients with peritoneal carcinomatosis, in different settings. There is some concern about an over-risk of anastomotic leakage (AL) with PIPAC jeopardizing a combination with cytoreductive surgery. This study used a healthy swine model to compare the postoperative AL rate between PIPAC and HIPEC with digestive resection and to analyze macrocirculation and microcirculation parameters.

METHODS

Segmental colonic resection with a handsewn anastomosis was performed on 16 healthy pigs; 8 pigs had a PIPAC procedure with 7.5 mg/m² cisplatin (PIPAC group), and 8 pigs had a closed HIPEC procedure with 70 mg/m² cisplatin and 42 °C as the target intraperitoneal temperature (HIPEC group). Pigs were kept alive for 8 days, then sacrificed and autopsied to look for AL, which was defined as local abscess or digestive fluid leakage when pressure was applied to the anastomosis. Food intake, weight, and core temperature were monitored postoperatively. Macrocirculation (heart rate, systolic blood pressure) and microcirculation parameters (percentage of perfused vessels, perfused vessels density, DeBacker score) were evaluated intraoperatively at five timepoints. Results were compared between pigs with AL and those without.

RESULTS

The HIPEC group had no AL, but 3 of 8 pigs (37.5%) had AL in the PIPAC group (p = 0.20). Heart rate and core temperature showed perioperative increases in the HIPEC group. Intraoperatively, heart rate was higher in the HIPEC group at the two last timepoints (123 vs. 93 bpm, p = 0.031, and 110 vs. 85 bpm, p = 0.010, at timepoints 3 and 4, respectively). Other macrocirculatory and microcirculatory parameters showed no significant differences.

CONCLUSION

In this healthy swine model, PIPAC might have increased AL incidence compared to HIPEC. This potential over-risk did not seem to be related to changes in the microcirculation. PIPAC should probably not be used with digestive resection and should be avoided in cases of perioperative serosal injury.

Bioresorbable photonic devices for the spectroscopic characterization of physiological status and neural activity

Capabilities in real-time monitoring of internal physiological processes could inform pharmacological drug-delivery schedules, surgical intervention procedures and the management of recovery and rehabilitation. Current methods rely on external imaging techniques or implantable sensors, without the ability to provide continuous information over clinically relevant timescales, and/or with requirements in surgical procedures with associated costs and risks. Here, we describe injectable classes of photonic devices, made entirely of materials that naturally resorb and undergo clearance from the body after a controlled operational lifetime, for the spectroscopic characterization of targeted tissues and biofluids. As an example application, we show that the devices can be used for the continuous monitoring of cerebral temperature, oxygenation and neural activity in freely moving mice. These types of devices should prove useful in fundamental studies of disease pathology, in neuroscience research, in surgical procedures and in monitoring of recovery from injury or illness.

In vivo validation of a miniaturized electrochemical oxygen sensor for measuring intestinal oxygen tension

Recent advances in the fields of electronics and microfabrication techniques have led to the development of implantable medical devices for use within the field of precision medicine. Monitoring visceral surface tissue O₂ tension (PTo2) by means of an implantable sensor is potentially useful in many clinical situations, including the perioperative management of patients undergoing intestinal resection and anastomosis. This concept could provide a means by which treatment could be tailored to individual patients. This study describes the in vivo validation of a novel, miniaturized electrochemical O₂ sensor to provide real-time data on intestinal PTo2. A single O₂ sensor was placed onto the serosal surface of the small intestine of anesthetized rats that were exposed to ischemic (superior mesenteric artery occlusion) and hypoxemic (alterations in inspired fractional O₂ concentrations) insults. Control experiments demonstrated that the sensors can function and remain stable in an in vivo environment. Intestinal PTo2 decreased following superior mesenteric artery occlusion and with reductions in inspired O₂ concentrations. These results were reversible after reinstating blood flow or by increasing inspired O₂ concentrations. We have successfully developed an anesthetized rat intestinal ischemic and hypoxic model for validation of a miniaturized O₂ sensor to provide real-time measurement of intestinal PTo2. Our results support further validation of the sensors in physiological conditions using a large animal model to provide evidence of their use in clinical applications where monitoring visceral surface tissue O₂ tension is important.NEW & NOTEWORTHY This is the first report of real-time continuous measurements of intestinal oxygen tension made using a microfabricated O₂ sensor. Using a developed rodent model, we have validated this sensor's ability to accurately measure dynamic and reversible changes in intestinal oxygenation that occur through ischemic and hypoxemic insults. Continuous monitoring of local intestinal oxygenation could have value in the postoperative monitoring of patients having undergone intestinal surgery.

Remote computer-assisted analysis of ICG fluorescence signal for evaluation of small intestinal anastomotic perfusion: a blinded, randomized, experimental trial

BACKGROUND

Indocyanine green fluorescence imaging (ICG-FI) may be used to visualize intestinal perfusion prior to anastomosis. Methods for quantification of the fluorescence signal are required to ensure an objective evaluation. The aim of this study was to evaluate a method for quantification of relative perfusion and to investigate the correlation between the perfusion level and the anastomotic strength.

METHOD

This blinded, randomized, experimental trial included twenty pigs. Each pig received three small intestinal anastomoses with 30%, 60%, or 100% perfusion, respectively. The perfusion levels were determined relative to healthy intestine using ICG-FI. Ischemia was induced by mesenteric ligation and the perfusion level of each anastomosis was determined using a software-based analysis of the fluorescence signal. On postoperative day 5, the anastomoses were subjected to tensile strength test and histopathological assessment.

RESULTS

No anastomotic leakage occurred. The tensile strength of the 30% perfusion group was 9.09 N, which was significantly lower than the 60% perfusion group (11.5 N) and the 100% perfusion group (12.9 N). The difference between the 60% perfusion group and the 100% perfusion group was not significant. The histopathological assessment showed no significant differences between perfusion groups.

CONCLUSIONS

A reduction in blood supply to 30%, as determined by ICG-FI, in small intestinal anastomoses was necessary to demonstrate a decrease in tensile strength.

HYPerspectral Enhanced Reality (HYPER): a physiology-based surgical guidance tool

BACKGROUND

HSI is an optical technology allowing for a real-time, contrast-free snapshot of physiological tissue properties, including oxygenation. Hyperspectral imaging (HSI) has the potential to quantify the gastrointestinal perfusion intraoperatively. This experimental study evaluates the accuracy of HSI, in order to quantify bowel perfusion, and to obtain a superposition of the hyperspectral information onto real-time images.

METHODS

In 6 pigs, 4 ischemic bowel loops were created (A, B, C, D) and imaged at set time points (from 5 to 360 min). A commercially available HSI system provided pseudo-color maps of the perfusion status (StO2, Near-InfraRed perfusion) and the tissue water index. An ad hoc software was developed to superimpose HSI information onto the live video, creating the HYPerspectral-based Enhanced Reality (HYPER). Seven regions of interest (ROIs) were identified in each bowel loop according to StO2 ranges, i.e., vascular (VASC proximal and distal), marginal vascular (MV proximal and distal), marginal ischemic (MI proximal and distal), and ischemic (ISCH). Local capillary lactates (LCL), reactive oxygen species (ROS), and histopathology were measured at the ROIs. A machine-learning-based prediction algorithm of LCL, based on the HSI-StO2%, was trained in the 6 pigs and tested on 5 additional animals.

RESULTS

HSI parameters (StO2 and NIR) were congruent with LCL levels, ROS production, and histopathology damage scores at the ROIs discriminated by HYPER. The global mean error of LCL prediction was 1.18 ± 1.35 mmol/L. For StO2 values > 30%, the mean error was 0.3 ± 0.33.

CONCLUSIONS

HYPER imaging could precisely quantify the overtime perfusion changes in this bowel ischemia model.