How to assess intestinal viability during surgery: A review of techniques

Hybrid surgery for imminent rupture of superior mesenteric artery aneurysms

A case of a superior mesenteric artery aneurysm presented with an impending rupture. The aneurysm was located in the right side branch of the superior mesenteric artery. The patient underwent an emergency hybrid procedure, which included aneurysm embolization and exclusion of the aneurysm with an endoluminal stent graft. The blood supply to the right side branch was restored by bypass grafting with an autologous vein graft. The postoperative course was uneventful with no evidence of mesenteric ischemia. Postoperative computed tomography angiography confirmed complete aneurysm exclusion and sac size reduction, as well as patency of the stent graft and bypass.

Local Myoelectric Sensing During Human Colonic Tissue Perfusion

Objectives: Anastomotic leakage (AL) is one of the most devastating complications after colorectal surgery. The verification of the adequate perfusion of the anastomosis is essential to ensuring anastomosis integrity following colonic resections. This study aimed to evaluate the efficacy of measuring the electrical activity of the colonic muscularis externa at an anastomosis site for perfusion analysis following colorectal surgery. Methods: Strips of human isolated colon were maintained in a horizontal tissue bath to record spontaneous contractions and myoelectric activity and spike potentials (using a bipolar electrode array for the wireless transmission of myoelectric data-the xBar system) from the circular muscle. Intraoperative myoelectric signal assessment was performed by placing the electrode array on the colon prior to and following mesenteric artery ligation, just prior to colonic resection. Results: In human isolated colon, the amplitude, duration, and frequency of contractions were inhibited during hypoxia by >80% for each measurement, compared to control values and time-matched oxygenated muscle. Intraoperative (N = 5; mean age, 64.8 years; range, 54-74 years; 60% females) myoelectric signal assessment revealed a decline in spike rate following arterial ligation, with a mean reduction of 112.64 to 51.13 spikes/min (p < 0.0008). No adverse events were observed during the study, and the device did not substantially alter the surgical procedure. Conclusions: The electrical and contraction force of the human colon was reduced by ischemia, both in vitro and in vivo. These preliminary findings also suggest the potential of the xBar system to measure such changes during intraoperative and possibly postoperative periods to predict the risk of anastomotic viability as a surrogate of evolving dehiscence.

Real-time quantification of laser speckle contrast imaging during intestinal laparoscopic surgery: successful demonstration in a porcine intestinal ischemia model

BACKGROUND

Anastomotic leakage (AL) is a dreaded complication following colorectal cancer surgery, impacting patient outcome and leads to increasing healthcare consumption as well as economic burden. Bowel perfusion is a significant modifiable factor for anastomotic healing and thus crucial for reducing AL.

AIMS

The study aimed to calculate a cut-off value for quantified laser speckle perfusion units (LSPUs) in order to differentiate between ischemic and well-perfused tissue and to assess inter-observer reliability.

METHODS

LSCI was performed using a porcine ischemic small bowel loop model with the PerfusiX-Imaging® system. An ischemic area, a well-perfused area, and watershed areas, were selected based on the LSCI colormap. Subsequently, local capillary lactate (LCL) levels were measured. A logarithmic curve estimation tested the correlation between LSPU and LCL levels. A cut-off value for LSPU and lactate was calculated, based on anatomically ischemic and well-perfused tissue. Inter-observer variability analysis was performed with 10 observers.

RESULTS

Directly after ligation of the mesenteric arteries, differences in LSPU values between ischemic and well-perfused tissue were significant (p < 0.001) and increased significantly throughout all following measurements. LCL levels were significantly different (p < 0.001) at both 60 and 120 min. Logarithmic curve estimation showed an R2 value of 0.56 between LSPU and LCL values. A LSPU cut-off value was determined at 69, with a sensitivity of 0.94 and specificity of 0.87. A LCL cut-off value of 3.8 mmol/L was found, with a sensitivity and specificity of 0.97 and 1.0, respectively. There was no difference in assessment between experienced and unexperienced observers. Cohen's Kappa values were moderate to good (0.52-0.66).

CONCLUSION

Real-time quantification of LSPUs may be a feasible intraoperative method to assess tissue perfusion and a cut-off value could be determined with high sensitivity and specificity. Inter-observer variability was moderate to good, irrespective of prior experience with the technique.

Near-infrared indocyanine green angiography in recognizing bowel ischemia in emergency surgery: game changer or overrated?

Assessing bowel perfusion in emergency intestinal surgery can prove challenging even for experienced surgeons. The necessity of a technological tool assisting clinicians is undisputed. Near-infrared indocyanine green (NIR-ICG) angiography has been increasingly used in elective colorectal surgery to evaluate intestinal perfusion with promising results. This review aims to answer whether a similar outcome can be observed in acute cases of bowel ischemia. We conducted online research of the literature using keywords such as "indocyanine green", "bowel", "emergency" and "ischemia", to identify articles concerning the use of ICG-angiography in evaluating bowel perfusion during emergency operations. PubMed was the primary database. 11 articles were included in this systematic review with a total of 358 patients. Most papers showed a positive effect after using NIR-ICG-angiography, whereas one study indicated the limitations of the method by exhibiting increased reoperation and mortality rates. Moreover, a significant variation in indocyanine green (ICG) dose and fluorescence identification systems was observed. NIR-ICG-angiography has the potential to become a fundamental tool in emergency intestinal operations. Nevertheless, additional research, especially high-quality, randomized studies, as well as quantification techniques are still needed to support these preliminary observations.

Does Indocyanine Green Utilization during Esophagectomy Prevent Anastomotic Leaks? Systematic Review and Meta-Analysis

Background: Indocyanine Green (ICG) is a promising technique for the assessment of gastric conduit and anastomosis perfusion during esophagectomy. ICG integration may be helpful in minimizing the risk of anastomotic leak (AL). Literature evidence is sparse, while the real effect of ICG assessment on AL minimization remains unsolved. The aim of this systematic review and meta-analysis was to compare short-term outcomes between ICG-guided and non-ICG-guided (nICG) esophagogastric anastomosis during esophagectomy for cancer. Materials and Methods: PubMed, MEDLINE, Scopus, Web of Science, Cochrane Central Library, and ClinicalTrials.gov were queried up to 25 April 2024. Studies that reported short-term outcomes for ICG versus non-ICG-guided (nICG) anastomosis in patients undergoing esophagectomy were considered. Primary outcome was AL. Risk ratio (RR) and standardized mean difference (SMD) were utilized as effect size measures, whereas to assess relative inference we used 95% confidence intervals (95% CI). Results: Overall, 1399 patients (11 observational studies) were included. Overall, 576 (41.2%) underwent ICG gastric conduit assessment. The patients' ages ranged from 22 to 91 years, with 73% being male. The cumulative incidence of AL was 10.4% for ICG and 15.4% for nICG. Compared to nICG, ICG utilization was related to a reduced risk for postoperative AL (RR 0.48; 95% CI 0.23-0.99; p = 0.05). No differences were found in terms of pulmonary complications (RR 0.83), operative time (SMD -0.47), hospital length of stay (SMD -0.16), or 90-day mortality (RR 1.70). Conclusions: Our study seems to indicate a potential impact of ICG in reducing post-esophagectomy AL. However, because of limitations in the design of the included studies, allocation/reporting bias, variable definitions of AL, and heterogeneity in ICG use, caution is required to avoid potential overestimation of the ICG effect.

Usefulness of fluorescence imaging with indocyanine green for evaluation of bowel perfusion in the urgency setting: a systematic review and meta-analysis

INTRODUCTION

Fluorescence imaging with indocyanine green (ICG) has been extensively utilized to assess bowel perfusion in oncologic surgery. In the emergency setting, there are many situations in which bowel perfusion assessment is required. Large prospective studies or RCTs evaluating feasibility, safety and utility of ICG in the emergency setting are lacking. The primary aim is to assess the usefulness of ICG for evaluation of bowel perfusion in the emergency setting.

MATERIALS AND METHODS

The manuscript was drafted following the recommendations of Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA). A systematic literature search was carried out through Pubmed, Scopus, and the ISI Web of Science. Assessment of included study using the methodological index for nonrandomized studies (MINORS) was calculated. The meta-analysis was carried out in line with recommendations from the Cochrane Collaboration and Meta-analysis of Observational Studies in Epidemiology guidelines, and the Mantel-Haenszel random effects model was used to calculate effect sizes.

RESULTS

10 093 papers were identified. Eighty-four were reviewed in full-text, and 78 were excluded: 64 were case reports; 10 were reviews without original data; 2 were letters to the editor; and 2 contained unextractable data. Finally, six studies 22-27 were available for quality assessment and quantitative synthesis. The probability of reoperation using ICG fluorescence angiography resulted similar to the traditional assessment of bowel perfusion with a RD was -0.04 (95% CI: -0.147 to 0.060). The results were statistically significant P =0.029, although the heterogeneity was not negligible with a 59.9% of the I2 index. No small study effect or publication bias were found.

CONCLUSIONS

This first metanalysis on the use of IGC fluorescence for ischemic bowel disease showed that this methodology is a safe and feasible tool in the assessment of bowel perfusion in the emergency setting. This topic should be further investigated in high-quality studies.

Acute Small-bowel Obstruction: An Appraisal of Common Etiology and Management at the Federal Medical Centre, Keffi, North-central Nigeria

BACKGROUND

Acute small intestinal obstruction is a common surgical emergency in the sub-Saharan region. Over the decades, complicated inguinal hernias have been identified as a leading cause. However, we observed from our clinical practice that complicated inguinal hernias were not the most common etiology.

AIMS AND OBJECTIVES

This study aimed to evaluate the common etiology of acute small bowel obstruction in the study center and compare our findings with that from other centers and existing literature.

MATERIALS AND METHODS

This was a retrospective, cross sectional study carried out over a period of five years (January 2017 to December 2021). This study looked at the patients presenting with acute, mechanical, small bowel obstruction that did not respond to conservative treatment in our hospital facility. Relevant information were extracted from patients' clinical details and entered into the proforma prepared for this study.

RESULTS

A total of 147 patients were recruited into this study out of which 85(57.8%) were males and 62 (42.2%) were females (M:F=1.44:1). Majority (80.3%) of the patients that presented with post-operative bowel adhesion had previous appendectomy. Simple bowel obstruction was seen in 93 (63.3%) patients while strangulated obstruction and gangrenous bowel were seen in 26 (17.7%) patients and 22 (15.0%) patients respectively. Majority (47.6%) of the patients had adhesiolysis done while others had bowel resection.

CONCLUSION

The common cause of acute small bowel obstruction as observed in this study is post-operative adhesions arising from previous appendectomy and laparotomies.

Role of artificial intelligence in colorectal cancer

The sphere of artificial intelligence (AI) is ever expanding. Applications for clinical practice have been emerging over recent years. Although its uptake has been most prominent in endoscopy, this represents only one aspect of holistic patient care. There are a multitude of other potential avenues in which gastrointestinal care may be involved. We aim to review the role of AI in colorectal cancer as a whole. We performed broad scoping and focused searches of the applications of AI in the field of colorectal cancer. All trials including qualitative research were included from the year 2000 onwards. Studies were grouped into pre-operative, intra-operative and post-operative aspects. Pre-operatively, the major use is with endoscopic recognition. Colonoscopy has embraced the use for human derived classifications such as Narrow-band Imaging International Colorectal Endoscopic, Japan Narrow-band Imaging Expert Team, Paris and Kudo. However, novel detection and diagnostic methods have arisen from advances in AI classification. Intra-operatively, adjuncts such as image enhanced identification of structures and assessment of perfusion have led to improvements in clinical outcomes. Post-operatively, monitoring and surveillance have taken strides with potential socioeconomic and environmental savings. The uses of AI within the umbrella of colorectal surgery are multiple. We have identified existing technologies which are already augmenting cancer care. The future applications are exciting and could at least match, if not surpass human standards.

Impact of indocyanine green angiography on anastomotic dehiscence rate in colorectal surgery: a systematic review and meta-analysis of randomized studies

Anastomotic dehiscence, a feared complication in colorectal surgery, motivates the search for effective strategies to mitigate its risk. This meta-analysis encompasses all published randomized trials investigating and comparing the impact of indocyanine green (ICG) angiography on this complication. With four studies and 1,109 patients, the intraoperative ICG angiography group demonstrated a significant reduction in the overall rate of anastomotic dehiscence compared to the non-angiography group (7.3% vs. 11.5%; OR: 0.6; 95% CI: 0.4-0.9; p = 0.03). These differences were maintained in rectal surgery subgroup, with no prolongation of surgical time or increase in morbidity and mortality. There were no differences in the left colon surgery group. The evidence provided by this meta-analysis would support the effectiveness of ICG angiography in reducing the incidence of anastomotic leakage in colorectal surgery, advocating for its integration into routine surgical practice.

Identification of near-infrared characteristic bands of small bowel necrosis based on cellwise detection algorithm

The near-infrared spectroscopy is often used to distinguish small bowel necrosis due to necrotizing enterocolitis (NEC). The characteristic bands of small bowel necrosis, as an important basis for evaluating the confidence of the differentiation results, are challenging to identify quickly. In this study, we proposed to identify characteristic bands of lesion samples based on hyperspectral imaging (HSI) and cellwise outlier detection. Rabbits were used as an animal model to simulate the clinical symptoms of NEC. The rabbits were detected at intervals of 10, 30, 60, and 90 min. The characteristic bands were identified within the same rabbit, between different rabbits and at different times. The result showed the bands near 763 nm, corresponding to the absorption peak of deoxyhemoglobin, were the characteristic bands separating samples with NEC. The identification result was plausible because hypoxia was the main cause of NEC. The method was easy to perform.

Utilization of Indocyanine Green (ICG) Fluorescence in Patients with Pediatric Colorectal Diseases: The Current Applications and Reported Outcomes

In pediatric colorectal surgery, achieving and visualizing adequate perfusion during complex reconstructive procedures are paramount to ensure postoperative success. However, intraoperative identification of proper perfusion remains a challeng. This review synthesizes findings from the literature spanning from January 2010 to March 2024, sourced from Medline/PubMed, EMBASE, and other databases, to evaluate the role of indocyanine green (ICG) fluorescence imaging in enhancing surgical outcomes. Specifically, it explores the use of ICG in surgeries related to Hirschsprung disease, anorectal malformations, cloacal reconstructions, vaginal agenesis, bladder augmentation, and the construction of antegrade continence channels. Preliminary evidence suggests that ICG fluorescence significantly aids in intraoperative decision-making by improving the visualization of vascular networks and assessing tissue perfusion. Despite the limited number of studies, initial findings indicate that ICG may offer advantages over traditional clinical assessments for intestinal perfusion. Its application has demonstrated a promising safety profile in pediatric patients, underscoring the need for larger, prospective studies to validate these observations, quantify benefits, and further assess its impact on clinical outcomes. The potential of ICG to enhance pediatric colorectal surgery by providing real-time, accurate perfusion data could significantly improve surgical precision and patient recovery.

[Indications and surgical strategy for bowel resection in mesenteric ischemia : Resection margins considering current guidelines and literature as well as the influence of new technical possibilities]

Acute mesenteric ischemia (AMI) is still a time-critical and life-threatening clinical picture. If exploration of the abdominal cavity is necessary during treatment, an intraoperative assessment of which segments of the intestines have a sufficient potential for recovery must be made. These decisions are mostly based on purely clinical parameters, which are subject to high level of uncertainty. This review article provides an overview of how this decision-making process and the determination of resection margins can be improved using technical aids, such as laser Doppler flowmetry (LDF), indocyanine green (ICG) fluorescence angiography or hyperspectral imaging (HSI). Furthermore, this article compiles guideline recommendations on the role of laparoscopy and the value of a planned second-look laparotomy. In addition, an overview of strategies for preventing short bowel syndrome is given and other aspects, such as the timing and technical aspects of placement of a preternatural anus and an anastomosis are highlighted.

Navigating Abdominal Volvulus: A Comprehensive Review of Management Strategies

Abdominal volvulus represents a critical condition characterized by the abnormal twisting of the GI tract, potentially leading to obstruction and vascular compromise. Prompt recognition and appropriate management are essential to prevent complications and improve patient outcomes. This comprehensive review examines the anatomy, pathophysiology, clinical presentation, and diagnostic evaluation of, and management strategies for abdominal volvulus. Non-operative techniques, including detorsion and decompression, as well as surgical interventions, such as laparoscopic and open approaches, are discussed. Additionally, the importance of multidisciplinary collaboration and postoperative care is emphasized. Despite significant advancements, unresolved issues remain, necessitating further research to refine diagnostic and therapeutic approaches. Future directions, including exploring emerging technologies, offer promise for enhancing the management of this challenging condition. Overall, this review provides clinicians with valuable insights into the optimal management of abdominal volvulus, aiming to improve patient outcomes and enhance clinical practice.

Indocyanine green: The guide to safer and more effective surgery

In this editorial we comment on the article by Kalayarasan and co-workers published in the recent issue of the World Journal of Gastrointestinal Surgery. The authors present an interesting review on the use of indocyanine green fluorescence in different aspects of abdominal surgery. They also highlight future perspectives of the use of indocyanine green in mini-invasive surgery. Indocyanine green, used for fluorescence imaging, has been approved by the Food and Drug Administration and is safe for use in humans. It can be administered intravenously or intra-arterially. Since its advent, there have been several advancements in the applications of indocyanine green, especially in the surgical field, such as intraoperative mapping and biopsy of sentinel lymph node, measurement of hepatic function prior to resection, in neurosurgical cases to detect vascular anomalies, in cardiovascular cases for patency and assessment of vascular abnormalities, in predicting healing following amputations, in helping visualization of hepatobiliary anatomy and blood vessels, in reconstructive surgery, to assess flap viability and for the evaluation of tissue perfusion following major trauma and burns. For these reasons, the intraoperative use of indocyanine green has become common in a variety of surgical specialties and transplant surgery. Colorectal surgery has just lately begun to adopt this technique, particularly for perfusion visualization to prevent anastomotic leakage. The regular use of indocyanine green coupled with fluorescence angiography has recently been proposed as a feasible tool to help improve patient outcomes. Using the best available data, it has been shown that routine use of indocyanine green in colorectal surgery reduces the rates of anastomotic leak. The use of indocyanine green is proven to be safe, feasible, and effective in both elective and emergency scenarios. However, additional robust evidence from larger-scale, high-quality studies is essential before incorporating indocyanine green guided surgery into standard practice.

The Role of Indocyanine Green in Pediatric Gastrointestinal Surgery: Systematic Review

The use of near-infrared fluorescence imaging with indocyanine green (ICG) is actually considered as a very useful tool in decision-making strategy during challenging surgical procedures with a growing evidence in the literature. Our aim is to perform a systematic review focusing on ICG applications in gastrointestinal surgery. We conducted a systematic review with narrative synthesis in conformity with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using PubMed, Medline, and EMBASE databases to identify articles describing the gastrointestinal perioperative use of ICG in children. We extracted data on study design, demographics, surgical indications, ICG dose, and perioperative outcomes. Eleven articles, including 94 pediatric patients, from 2013 to 2022 met the inclusion criteria for narrative synthesis in our systematic review, of which 6/11 (54.5%) were case reports, 4/11 (36.4%) were retrospective studies, and 1/11 (0.1%) were case series. Current clinical applications of ICG in gastrointestinal pediatric surgery included: esophagogastric surgery in 4/11 articles (36.4%), intestinal and pancreatic surgery in 3/11 articles (27.2%), and colorectal surgery in 4/11 articles (36.4%). ICG fluorescence in gastrointestinal pediatric surgery is a promising and safe technology that facilitates intraoperative localization of anatomical structures to achieve a more precise dissection and avoid injury to other adjacent tissues. It can be considered as a meaningful tool for assessing intestinal viability, as it provides objective data on tissue perfusion, and can impact the intraoperative decision in reconstructive surgeries requiring anastomosis. Future studies are needed to confirm these initial promising results. The lack of comparative and prospective studies is still the main limitation.

Current status of indocyanine green fluorescent angiography in assessing perfusion of gastric conduit and oesophago-gastric anastomosis

Anastomotic leak (AL) remains a significant complication after esophagectomy. Indocyanine green fluorescent angiography (ICG-FA) is a promising and safe technique for assessing gastric conduit (GC) perfusion intraoperatively. It provides detailed visualization of tissue perfusion and has demonstrated usefulness in oesophageal surgery. GC perfusion analysis by ICG-FA is crucial in constructing the conduit and selecting the anastomotic site and enables surgeons to make necessary adjustments during surgery to potentially reduce ALs. However, anastomotic integrity involves multiple factors, and ICG-FA must be combined with optimization of patient and procedural factors to decrease AL rates. This review summarizes ICG-FA's current applications in assessing esophago-gastric anastomosis perfusion, including qualitative and quantitative analysis and different imaging systems. It also explores how fluorescent imaging could decrease ALs and aid clinicians in utilizing ICG-FA to improve esophagectomy outcomes.

Dye-free visualisation of intestinal perfusion using laser speckle contrast imaging in laparoscopic surgery: a prospective, observational multi-centre study

INTRODUCTION

Intraoperative perfusion imaging may help the surgeon in creating the intestinal anastomoses in optimally perfused tissue. Laser speckle contrast imaging (LSCI) is such a perfusion visualisation technique that is characterized by dye-free, real-time and continuous imaging. Our aim is to validate the use of a novel, dye-free visualization tool to detect perfusion deficits using laparoscopic LSCI.

METHODS

In this multi-centre study, a total of 64 patients were imaged using the laparoscopic laser speckle contrast imager. Post-operatively, surgeons were questioned if the additional visual feedback would have led to a change in clinical decision-making.

RESULTS

This study suggests that the laparoscopic laser speckle contrast imager PerfusiX-Imaging is able to image colonic perfusion. All images were clear and easy to interpret for the surgeon. The device is non-disruptive of the surgical procedure with an average added surgical time of 2.5 min and no change in surgical equipment. The potential added clinical value is accentuated by the 17% of operating surgeons indicating a change in anastomosis location. Further assessment and analysis of both white light and PerfusiX perfusion images by non-involved, non-operating surgeons showed an overall agreement of 80%.

CONCLUSION

PerfusiX-Imaging is a suitable laparoscopic perfusion imaging system for colon surgery that can visualize perfusion in real-time with no change in surgical equipment. The additional visual feedback could help guide the surgeons in placing the anastomosis at the most optimal site.

Intra-abdominal laparoscopic assessment of organs perfusion using imaging photoplethysmography

BACKGROUND

An objective evaluation of the functional state and viability of biological tissues during minimally invasive surgery remains unsolved task. Various non-contact methods for evaluating perfusion during laparoscopic surgery are discussed in the literature, but so far there have been no reports of their use in clinical settings.

METHODS AND PATIENTS

Imaging photoplethysmography (iPPG) is a new method for quantitative assessment of perfusion distribution along the tissue. This is the first study in which we demonstrate successful use of iPPG to assess perfusion of organs during laparoscopic surgery in an operation theater. We used a standard rigid laparoscope connected to a standard digital monochrome camera, and abdominal organs were illuminated by green light. A distinctive feature is the synchronous recording of video frames and electrocardiogram with subsequent correlation data processing. During the laparoscopically assisted surgeries in nine cancer patients, the gradient of perfusion of the affected organs was evaluated. In particular, measurements were carried out before preparing a part of the intestine or stomach for resection, after anastomosis, or during physiological tests.

RESULTS

The spatial distribution of perfusion and its changes over time were successfully measured in all surgical cases. In particular, perfusion gradient of an intestine before resection was visualized and quantified by our iPPG laparoscope in all respective cases. It was also demonstrated that systemic administration of norepinephrine leads to a sharper gradient between well and poorly perfused areas of the colon. In four surgical cases, we have shown capability of the laparoscopic iPPG system for intra-abdominal assessment of perfusion in the anastomosed organs. Moreover, good repeatability of continuous long-term measurements of tissue perfusion inside the abdominal cavity was experimentally demonstrated.

CONCLUSION

Our study carried out in real clinical settings has shown that iPPG laparoscope is feasible for intra-abdominal visualization and quantitative assessment of perfusion distribution.

Assessment and comparison of microcirculation and macrocirculation in horses undergoing emergency exploratory celiotomy versus elective surgical procedures

OBJECTIVE

To assess oral buccal microcirculation by hand-held videomicroscopy in horses during colic surgery, comparing microcirculation values with macrocirculatory parameters and with those of healthy elective surgical horses.

STUDY DESIGN

Clinical prospective study.

ANIMALS

Client-owned horses (nine in the colic group; 11 in the elective group).

METHODS

In the colic group, buccal mucosal side stream dark-field microscopy (DFM) videos, cardiac output (CO), mean arterial pressure (MAP), and lactate were obtained at three timepoints under general anesthesia (30, 90, and 150 min after induction). Video analysis was used to determine total vessel density, proportion of perfused vessels, perfused vessel density, and heterogeneity index. Dark-field microscopy videos, MAP, and lactate were obtained at a single timepoint under general anesthesia (45 min after induction) in the elective group.

RESULTS

There were no differences in microcirculatory parameters between colic and elective horses, nor was there a difference across timepoints in the colic group. There was a weak negative correlation between microvascular parameters and CO (rho = -0.23).

CONCLUSION

The colic group did not have decreased microcirculation in comparison with the healthy elective group. Dark-field microscopy did not correlate well with macrocirculatory parameters in the colic group.

IMPACT

Dark-field microscopy may not be a sensitive enough indicator to detect differences in microcirculation between colic and elective groups. The lack of difference in microcirculation may be due to sample size, probe location, or variation in disease severity.

Real-time quantification of bowel perfusion using Laparoscopic Laser Speckle Contrast Imaging (LSCI) in a porcine model

BACKGROUND/PURPOSE

Real-time quantification of tissue perfusion can improve intraoperative surgical decision making. Here we demonstrate the utility of Laser Speckle Contrast Imaging as an intra-operative tool that quantifies real-time regional differences in intestinal perfusion and distinguishes ischemic changes resulting from arterial/venous obstruction.

METHODS

Porcine models (n = 3) consisted of selectively devascularized small bowel loops that were used to measure the perfusion responses under conditions of control/no vascular occlusion, arterial inflow occlusion, and venous outflow occlusion using laser speckle imaging and indocyanine green fluoroscopy. Laser Speckle was also used to assess perfusion differences between small bowel antimesenteric-antimesenteric and mesenteric-mesenteric anastomoses. Perfusion quantification was measured in relative perfusion units calculated from the laser speckle perfusion heatmap.

RESULTS

Laser Speckle distinguished between visually identified perfused, watershed, and ischemic intestinal segments with both color heatmap and quantification (p < .00001). It detected a continuous gradient of relative intestinal perfusion as a function of distance from the stapled ischemic bowel edge. Strong positive linear correlation between relative perfusion units and changes in mean arterial pressure resulting from both arterial (R2 = .96/.79) and venous pressure changes (R2 = .86/.96) was observed. Furthermore, Laser Speckle showed that the antimesenteric anastomosis had a higher perfusion than mesenteric anastomosis (p < 0.01).

CONCLUSIONS

Laser Speckle Contrast Imaging provides objective, quantifiable tissue perfusion information in both color heatmap and relative numerical units. Laser Speckle can detect spatial/temporal differences in perfusion between antimesenteric and mesenteric borders of a bowel segment and precisely detect perfusion changes induced by progressive arterial/venous occlusions in real-time.

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.

Discrimination between normal and necrotic small intestinal tissue using hyperspectral imaging and unsupervised classification

Objective and automatic clinical discrimination of normal and necrotic sites of small intestinal tissue remains challenging. In this study, hyperspectral imaging (HSI) and unsupervised classification techniques were used to distinguish normal and necrotic sites of small intestinal tissues. Small intestinal tissue hyperspectral images of eight Japanese large-eared white rabbits were acquired using a visible near-infrared hyperspectral camera, and K-means and density peaks (DP) clustering algorithms were used to differentiate between normal and necrotic tissue. The three cases in this study showed that the average clustering purity of the DP clustering algorithm reached 92.07% when the two band combinations of 500-622 and 700-858 nm were selected. The results of this study suggest that HSI and DP clustering can assist physicians in distinguishing between normal and necrotic sites in the small intestine in vivo.

Is ICG essential in all colorectal surgery? A 3-year experience in a single center: a cohort study

INTRODUCTION AND OBJECTIVES

Indocyanine green (ICG) was introduced as a promising diagnostic tool to provide real-time assessment of intestinal vascularization. Nevertheless, it remains unclear whether ICG could reduce the rate of postoperative AL. The objective of this study is to assess its usefulness and to determine in which patients is most useful and would benefit the most from the use of ICG for intraoperative assessment of colon perfusion.

METHODS

A retrospective cohort study was conducted in a single center, including all patients who underwent colorectal surgery with intestinal anastomosis between January 2017 and December 2020. The results of patients in whom ICG was used prior to bowel transection were compared with the results of the patients in whom this technique was not used. Propensity score matching (PSM) was employed to compare groups with and without ICG.

RESULTS

A total of 785 patients who underwent colorectal surgery were included. The operations performed were right colectomies (35.0%), left colectomies (48.3%), and rectal resections (16.7%). ICG was used in 280 patients. The mean time since the infusion of ICG until detection of fluorescence in the colon wall was 26.9 ± 1.2 s. The section line was modified in 4 cases (1.4%) after ICG due to a lack of perfusion in the chosen section line. Globally, a non-statistically significant increase in anastomotic leak rate was observed in the group without ICG (9.3% vs. 7.5%; p = 0.38). The result of the PSM was a coefficient of 0.026 (CI - 0.014 to 0.065, p = 0.207).

CONCLUSIONS

ICG is a safe and useful tool to assess the perfusion of the colon prior to performing the anastomosis in colorectal surgery. However, in our experience, it did not significantly lower the anastomotic leakage rate.

A quantitative evaluation of the effect of foreign body obstruction and enterectomy technique on canine small intestinal microvascular health

OBJECTIVE

To investigate sidestream dark field (SDF) videomicroscopy as an objective measure of intestinal viability and determine the effects of enterectomy techniques on intestinal microvasculature in dogs with foreign body obstructions.

STUDY DESIGN

Prospective, randomized, clinical trial.

ANIMALS

A total of 24 dogs with an intestinal foreign body obstruction and 30 systemically healthy dogs.

METHODS

An SDF videomicroscope imaged the microvasculature at the site of the foreign body. Subjectively viable intestine received an enterotomy whereas nonviable intestine received an enterectomy using a handsewn (4-0 polydioxanone, simple continuous) or a functional end-to-end stapled technique (GIA 60 blue, TA 60 green) was used on an alternating basis. The microvasculature adjacent to the enterectomy was interrogated. Quantitative measures of microvascular health were calculated for each site and compared with healthy dogs.

RESULTS

Microvascular density (mean ± SD) at the site of obstruction (140.84 ± 77.40) was lower than healthy controls (251.72 ± 97.10, p < .01). There was no difference in microvascular parameters (density or perfused boundary region, PBR) between obstructed dogs with subjectively viable and nonviable intestine (p > .14). The density (p = .66) and PBR of microvessels (p = .76) adjacent to the sutured enterectomy or TA green staple line did not differ.

CONCLUSION

Sidestream dark field videomicroscopy can identify obstructed intestine and quantitate the severity of microvascular compromise. Handsewn and stapled enterectomies equally preserve perfusion.

CLINICAL SIGNIFICANCE

Stapled enterectomies do not lead to greater vascular compromise than handsewn enterectomies.

Quantitative perfusion assessment using indocyanine green during surgery - current applications and recommendations for future use

PURPOSE

Incorrect assessment of tissue perfusion carries a significant risk of complications in surgery. The use of near-infrared (NIR) fluorescence imaging with Indocyanine Green (ICG) presents a possible solution. However, only through quantification of the fluorescence signal can an objective and reproducible evaluation of tissue perfusion be obtained. This narrative review aims to provide an overview of the available quantification methods for perfusion assessment using ICG NIR fluorescence imaging and to present an overview of current clinically utilized software implementations.

METHODS

PubMed was searched for clinical studies on the quantification of ICG NIR fluorescence imaging to assess tissue perfusion. Data on the utilized camera systems and performed methods of quantification were collected.

RESULTS

Eleven software programs for quantifying tissue perfusion using ICG NIR fluorescence imaging were identified. Five of the 11 programs have been described in three or more clinical studies, including Flow® 800, ROIs Software, IC Calc, SPY-Q™, and the Quest Research Framework®. In addition, applying normalization to fluorescence intensity analysis was described for two software programs.

CONCLUSION

Several systems or software solutions provide a quantification of ICG fluorescence; however, intraoperative applications are scarce and quantification methods vary abundantly. In the widespread search for reliable quantification of perfusion with ICG NIR fluorescence imaging, standardization of quantification methods and data acquisition is essential.

Hyperspectral Imaging-A Novel Tool to Assess Tissue Perfusion and Oxygenation in Esophageal Anastomoses

Anastomotic stricture and leakage are common complications after repair of esophageal atresia (EA). A compromised perfusion of the anastomosis is a contributing factor. Hyperspectral imaging (HSI) is an ultrashort noninvasive method to measure tissue perfusion. We present two cases of with tracheoesophageal fistula (TEF)/EA repair, in whom we applied HSI: the first patient was a newborn with EA type C who underwent open TEF repair. The second one had an EA type A and cervical esophagostomy, in whom we performed gastric transposition. In both patients, HSI confirmed a good tissue perfusion of the later anastomosis. The postoperative course was uneventful and both patients are on full enteral feeds. We conclude that HSI is a safe and noninvasive tool that allows near real-time assessment of tissue perfusion and can contribute to the identification of the optimal anastomotic region during pediatric esophageal surgery.

Experimental evaluation of laparoscopic laser speckle contrast imaging to visualize perfusion deficits during intestinal surgery

BACKGROUND

Ischemia at the site of an intestinal anastomosis is one of the most important risk factors for anastomotic leakage (AL). Consequently, adequate intestinal microperfusion is essential for optimal tissue oxygenation and anastomotic healing. As visual inspection of tissue viability does not guarantee an adequate objective evaluation of intestinal microperfusion, surgeons are in dire need of supportive tools to decrease anastomotic leakage after colorectal surgery.

METHODS

In this feasibility study, laparoscopic laser speckle contrast imaging (LSCI) was used to evaluate intestinal microperfusion in an experimental ischemic bowel loop model. Both large and small ischemic loops were created from the small intestine of a pig; each loop was divided into 5 regions of interest (ROI) with varying levels of ischemia. Speckle contrast and local capillary lactate (LCL) was measured in all ROIs.

RESULTS

Both real-time visualization of intestinal microperfusion and induced perfusion deficits was achieved in all bowel loops. As a result, the emergence of regions of intestinal ischemia could be predicted directly after iatrogenic perfusion limitation, whereas without LSCI signs of decreased intestinal viability could only be seen after 30 minutes. Additionally, a significant relation was found between LCL and LSCI.

CONCLUSION

In conclusion, LSCI can achieve real-time intraoperative visualization of intestinal microperfusion deficits, allowing for accurate prediction of long-term postoperative ischemic complications. With this revealing capacity, LSCI could potentially facilitate surgical decision-making when constructing intestinal anastomoses in order to mitigate ischemia-related complications such as AL.

The impact of nitroglycerine and volume on gastric tube microperfusion assessed by indocyanine green fluorescence imaging

The influence of hypervolemia and intraoperative administration of nitroglycerine on gastric tube microperfusion remains unclear The present study aimed to investigate the impact of different hemodynamic settings on gastric tube microperfusion quantified by fluorescence imaging with Indocyanine green (ICG-FI) as a promising tool for perfusion evaluation. Three groups with seven pigs each were formed using noradrenaline, nitroglycerin, and hypervolemia for hemodynamic management, respectively. ICG-FI, hemodynamic parameters, and transit-time flow measurement (TTFM) in the right gastroepiploic artery were continuously assessed. Fluorescent microspheres (FM) were administered, and the partial pressure of tissue oxygen was quantified. The administration of nitroglycerine and hypervolemia were both associated with significantly impaired microperfusion compared to the noradrenaline group quantified by ICG-FI. Even the most minor differences in microperfusion could be sufficiently predicted which, however, could not be represented by the mean arterial pressure measurement. Histopathological findings supported these results with a higher degree of epithelial damage in areas with impaired perfusion. The values measured by ICG-FI significantly correlated with the FM measurement. Using tissue oxygenation and TTFM for perfusion measurement, changes in microperfusion could not be comprehended. Our results support current clinical practice with restrictive volume and catecholamine administration in major surgery. Hypervolemia and continuous administration of nitroglycerine should be avoided.

When should indocyanine green be assessed in colorectal surgery, and at what distance from the tissue? Quantitative measurement using the SERGREEN program

BACKGROUND

Suture dehiscence is one of the most feared postoperative complications. Correct intestinal vascularization is essential for its prevention. Indocyanine green (ICG) is one of the methods used to assess vascularization, but this assessment is usually subjective. Our group designed the SERGREEN program to obtain an objective measurement of the degree of vascularization. We do not know how long after ICG administration the fluorescence of the tissues should be evaluated, or how far away the measurement should be performed. The aim of this study is to establish the optimal moment and distance for analyzing the fluorescence saturation of ICG.

METHODS

Prospective observational study in patients undergoing elective laparoscopic colorectal surgery. The optimal time for ICG analysis was tested in a sample of 20 patients (10 right colon and 10 left colon), and the optimal distance in a sample of ten patients. ICG was administered intravenously, and colon vascularization was quantified using SERGREEN; RGB (Red, Green, Blue) encoding was used. The intensity curve of the ICG was analyzed for ten minutes after its administration. Distances of 1, 3, and 5 cm were tested.

RESULTS

The intensity of fluorescence increased until 1.5 min after ICG administration (reaching figures of 112.49 in the right colon and 93.95 in the left). It then remained fairly stable until 3.5 min (98.49 in the right and 83.35 in the left), at which point it began to decrease gradually. ICG saturation was inversely proportional to the distance between the camera and the tissue. The best distance was 5 cm, where the confidence interval was narrower [CI 86.66-87.53].

CONCLUSION

The optimal time for determining ICG in the colon is between 1.5 and 3.5 min, in both right and left colon. The optimal distance is 5 cm. This information will help to establish parameters of comparison in normal and pathological situations.

Assessment of Intestinal Ischemia-Reperfusion Injury Using Diffuse Reflectance VIS-NIR Spectroscopy and Histology

A porcine model was used to investigate the feasibility of using VIS-NIR spectroscopy to differentiate between degrees of ischemia-reperfusion injury in the small intestine. Ten pigs were used in this study and four segments were created in the small intestine of each pig: (1) control, (2) full arterial and venous mesenteric occlusion for 8 h, (3) arterial and venous mesenteric occlusion for 2 h followed by reperfusion for 6 h, and (4) arterial and venous mesenteric occlusion for 4 h followed by reperfusion for 4 h. Two models were built using partial least square discriminant analysis. The first model was able to differentiate between the control, ischemic, and reperfused intestinal segments with an average accuracy of 99.2% with 10-fold cross-validation, and the second model was able to discriminate between the viable versus non-viable intestinal segments with an average accuracy of 96.0% using 10-fold cross-validation. Moreover, histopathology was used to investigate the borderline between viable and non-viable intestinal segments. The VIS-NIR spectroscopy method together with a PLS-DA model showed promising results and appears to be well-suited as a potentially real-time intraoperative method for assessing intestinal ischemia-reperfusion injury, due to its easy-to-use and non-invasive nature.