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

Novel Intraoperative Imaging of Gastric Tube Perfusion during Oncologic Esophagectomy—A Pilot Study Comparing Hyperspectral Imaging (HSI) and Fluorescence Imaging (FI) with Indocyanine Green (ICG)

Background: Novel intraoperative imaging techniques, namely, hyperspectral (HSI) and fluorescence imaging (FI), are promising with respect to reducing severe postoperative complications, thus increasing patient safety. Both tools have already been used to evaluate perfusion of the gastric conduit after esophagectomy and before anastomosis. To our knowledge, this is the first study evaluating both modalities simultaneously during esophagectomy. Methods: In our pilot study, 13 patients, who underwent Ivor Lewis esophagectomy and gastric conduit reconstruction, were analyzed prospectively. HSI and FI were recorded before establishing the anastomosis in order to determine its optimum position. Results: No anastomotic leak occurred during this pilot study. In five patients, the imaging methods resulted in a more peripheral adaptation of the anastomosis. There were no significant differences between the two imaging tools, and no adverse events due to the imaging methods or indocyanine green (ICG) injection occurred. Conclusions: Simultaneous intraoperative application of both modalities was feasible and not time consuming. They are complementary with regard to the ideal anastomotic position and may contribute to better surgical outcomes. The impact of their simultaneous application will be proven in consecutive prospective trials with a large patient cohort.

Anastomotic Technique-How to Optimize Success and Minimize Leak Rates

Determining when to perform a bowel anastomosis and whether to divert can be difficult, as an anastomosis made in a high-risk patient or setting has potential for disastrous consequences. While the surgeon has limited control over patient-specific characteristics, the surgeon can control the technique used for creating anastomoses. Protecting and ensuring a vigorous blood supply is fundamental, as is mobilizing bowel completely, and employing adjunctive techniques to attain reach without tension. There are numerous ways to create anastomoses, with variations on the segment and configuration of bowel used, as well as the materials used and surgical approach. Despite numerous studies on the optimal techniques for anastomoses, no one method has prevailed. Without clear evidence on the best anastomotic technique, surgeons should focus on adhering to good technique and being comfortable with several configurations for a variety of conditions.

Single Snapshot Imaging of Optical Properties (SSOP) for Perfusion Assessment during Gastric Conduit Creation for Esophagectomy: An Experimental Study on Pigs

Anastomotic leakage (AL) is a serious complication occurring after esophagectomy. The current knowledge suggests that inadequate intraoperative perfusion in the anastomotic site contributes to an increase in the AL rate. Presently, clinical estimation undertaken by surgeons is not accurate and new technology is necessary to improve the intraoperative assessment of tissue oxygenation. In the present study, we demonstrate the application of a novel optical technology, namely Single Snapshot imaging of Optical Properties (SSOP), used to quantify StO2% in an open surgery experimental gastric conduit (GC) model. After the creation of a gastric conduit, local StO2% was measured with a preclinical SSOP system for 60 min in the antrum (ROI-A), corpus (ROI-C), and fundus (ROI-F). The removed region (ROI-R) acted as ischemic control. ROI-R had statistically significant lower StO2% when compared to all other ROIs at T15, T30, T45, and T60 (p < 0.0001). Local capillary lactates (LCLs) and StO2% correlation was statistically significant (R = -0.8439, 95% CI -0.9367 to -0.6407, p < 0.0001). Finally, SSOP could discriminate resected from perfused regions and ROI-A from ROI-F (the future anastomotic site). In conclusion, SSOP could well be a suitable technology to assess intraoperative perfusion of GC, providing consistent StO2% quantification and ROIs discrimination.

Quantitative serosal and mucosal optical imaging perfusion assessment in gastric conduits for esophageal surgery: an experimental study in enhanced reality

INTRODUCTION/OBJECTIVE

Gastric conduit (GC) is used for reconstruction after esophagectomy. Anastomotic leakage (AL) incidence remains high, given the extensive disruption of the gastric circulation. Currently, there is no reliable method to intraoperatively quantify gastric perfusion. Hyperspectral imaging (HSI) has shown its potential to quantify serosal StO2. Confocal laser endomicroscopy (CLE) allows for automatic mucosal microcirculation quantification as functional capillary density area (FCD-A). The aim of this study was to quantify serosal and mucosal GC's microperfusion using HSI and CLE. Local capillary lactate (LCL) served as biomarker.

METHODS

GC was formed in 5 pigs and serosal StO2% was quantified at 3 regions of interest (ROI) using HSI: fundus (ROI-F), greater curvature (ROI-C), and pylorus (ROI-P). After intravenous injection of sodium-fluorescein (0.5 g), CLE-based mucosal microperfusion was assessed at the corresponding ROIs, and LCLs were quantified via a lactate analyzer.

RESULTS

StO2 and FCD-A at ROI-F (41 ± 10.6%, 3.3 ± 3.8, respectively) were significantly lower than ROI-C (68.2 ± 6.7%, p value: 0.005; 18.4 ± 7, p value: 0.01, respectively) and ROI-P (72 ± 10.4%, p value: 0.005; 15.7 ± 3.2 p value: 0.001). LCL value at ROI-F (9.6 ± 4.7 mmol/L) was significantly higher than at ROI-C (2.6 ± 1.2 mmol/L, p value: 0.04) and ROI-P (2.6 ± 1.3 mmol/L, p value: 0.04). No statistically significant difference was found in all metrics between ROI-C and ROI-P. StO2 correlated with FCD-A (Pearson's r = 0.67). The LCL correlated negatively with both FCD-A (Spearman's r =  - 0.74) and StO2 (Spearman's r =  -  0.54).

CONCLUSIONS

GC formation causes a drop in serosal and mucosal fundic perfusion. HSI and CLE correlate well and might become useful intraoperative tools.

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.

Real-time fluorescence image-guided gastrointestinal oncologic surgery: Towards a new era

Technological improvements are crucial in the evolution of surgery. Real-time fluorescence-guided surgery (FGS) has spread worldwide, mainly because of its usefulness during the intraoperative decision-making processes. The success of any gastrointestinal oncologic resection is based on the anatomical identification of the primary tumor and its regional lymph nodes. FGS allows also to evaluate the blood perfusion at the gastrointestinal stumps after colorectal or esophageal resections. Therefore, a reduction on the anastomotic leak rates has been postulated as one of the foreseeable benefits provided by the use of FGS in these procedures. Although the use of fluorescence in lymph node detection was initially described in breast cancer surgery, the technique is currently applied in gastric or splenic flexure cancers, as they both present complex and variable lymphatic drainages. FGS allows also to perform intraoperative lymphograms or sentinel lymph node biopsies. New applications of FGS are being developed to assist in the detection of peritoneal metastases or in the evaluation of the tumor resection margins. The present review aims to provide a general overview of the current status of real-time FGS in gastrointestinal oncologic surgery. We put a special focus on the different applications of FGS, discussing the main findings and limitations found in the contemporary literature and also the promising near future applications.

Usefulness of blood flow evaluation with indocyanine green fluorescence imaging during laparoscopic surgery for strangulated bowel obstruction: A cohort study

INTRODUCTION

Intestinal blood flow evaluation during strangulated bowel obstruction is often based on the subjective assessment of the operator. Therefore, we aimed to comprehensively determine the presence or absence of intestinal blood flow based on normal light and indocyanine green (ICG) fluorescence imaging. Moreover, we ascertained whether the chosen surgical plan was appropriate, based on the patients' postoperative course and pathological findings.

METHODS

All 14 patients diagnosed with strangulated bowel obstruction at our hospital who underwent laparoscopic surgery between July 2019 and January 2021 were enrolled. Surgical plans were chosen based on normal light imaging combined with near-infrared imaging after intravenous ICG injection. Intestinal resection was performed via a small laparotomy if resection was considered necessary. In the intestinal resection group, the presence of intestinal necrosis was examined based on the pathological findings of the resected specimens. In the intestinal preservation group, postoperative complications, such as delayed intestinal perforation and intestinal stricture, were examined.

RESULTS

Intestinal resection was performed in 4 cases. The pathological findings of the resected specimens showed necrosis of the small intestine in all cases. No intra-abdominal complication occurred any of the cases, and the median postoperative hospital stay was 9.9 days.

CONCLUSIONS

The selection of a surgical plan in conjunction with ICG fluorescence findings was valid in all 14 cases. ICG fluorescence imaging is useful in laparoscopic surgery for strangulated bowel obstruction and may be a novel method for evaluating intestinal blood flow during surgery.

Role of near-infrared fluorescence in colorectal surgery

Near-infrared fluorescence (NIRF) is a technique of augmented reality that, when applied in the operating theatre, allows the colorectal surgeon to visualize and assess bowel vascularization, to identify lymph nodes draining a cancer site and to identify ureters. Herein, we review the literature regarding NIRF in colorectal surgery.

Indocyanine green fluorescence angiography versus standard intraoperative methods for prevention of anastomotic leak in colorectal surgery: meta-analysis

BACKGROUND

Assessment of anastomotic blood perfusion with intraoperative indocyanine green fluorescence angiography (ICG-FA) may be effective in preventing anastomotic leak compared with standard intraoperative methods in colorectal surgery.

METHODS

MEDLINE, PubMed, Cochrane Central Register of Controlled Trials and the Cochrane Library were searched for RCTs and observational studies on intraoperative ICG-FA to May 2020. Odds ratios (ORs), risk differences and mean differences (MDs) were calculated with 95 per cent c.i. based on intention-to-treat analysis. The number needed to treat for an additional beneficial outcome was also estimated.

RESULTS

Twenty-five comparative studies included a total of 7735 patients. The use of intraoperative ICG fluorescence angiography was linked with a significant reduction in all grades anastomotic leak (OR 0.39 (95 per cent c.i. 0.31 to 0.49), P < 0.001; number needed to treat for an additional beneficial outcome (NNTB) 23) and length of hospital stay (MD -0.72 (95 per cent c.i. -1.22 to -0.21) days, P = 0.006). A significantly lower incidence of grade A (OR 0.33 (0.18 to 0.60), P < 0.001), grade B (OR 0.58 (0.35 to 0.97), P = 0.04) and grade C (OR 0.59 (0.38 to 0.92), P = 0.02) anastomotic leak was demonstrated in favour of ICG-FA. For low or ultra-low rectal resection, the odds of developing anastomotic leakage was 0.32 (0.23 to 0.45) (P < 0.001; NNTB 14). There were no differences in duration of surgery, and no adverse events related to ICG fluorescent injection.

CONCLUSION

The use of ICG-FA instead of standard intraoperative methods to assess anastomosis blood perfusion in colorectal surgery leads to a significant reduction in anastomotic leakage and in the need for surgical reintervention for anastomotic leak, especially in patients with low or ultra-low rectal resections.

The use of indocyanine green fluorescence to define bowel microcirculation during laparoscopic surgery for acute small bowel obstruction

AIM

Although there is growing evidence to support the feasibility of a minimally invasive approach for acute small bowel obstruction, the inability to adequately evaluate compromised bowel segments has been cited as a major limitation. The aim of this work is to report a novel application of extemporaneous indocyanine green (ICG) fluorescence to assess bowel viability where there is a concern for ischaemic damage.

METHOD

After the cause of obstruction has been identified and resolved, and where there are dubious signs of bowel ischaemia present, fluorescent selective angiography is undertaken. The segment of bowel in question is observed under both normal and fluorescent light to assess local microcirculation. The adequacy of both the arterial supply and the venous drainage is thus appraised to define bowel viability.

RESULTS

Among 71 patients who have undergone surgery for acute small bowel obstruction with a laparoscopic approach, seven received extemporaneous ICG fluorescence assessment of bowel viability. Different presentations with their relevant management are described.

CONCLUSIONS

Selective use of intraoperative fluorescent angiography may overcome some of the intrinsic limitations of laparoscopy in assessing bowel viability during surgery for acute small bowel obstruction.

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.

Surgical anatomy of the accessory middle colic artery: a meta-analysis with implications for splenic flexure cancer surgery

AIM

Surgical resection of splenic flexure cancers (SFCs) is technically demanding due to the complex regional anatomy, characterized by the presence of embryological adhesions, close proximity to the pancreas and spleen, and a highly heterogeneous arterial supply and lymphatic drainage. The accessory middle colic artery (AMCA) is increasingly being recognized as an important source of blood supply to the splenic flexure. The aim of this study is to determine the prevalence and anatomical features of the AMCA.

METHOD

A systematic search of the scientific literature was conducted on PubMed and Embase from inception to November 2020 to identify potentially eligible studies. Data were extracted and prevalence was pooled into a meta-analysis using MetaXL and Meta-Analyst software.

RESULTS

A total of 16 studies (n = 2203 patients) were included. The pooled prevalence (PP) of the AMCA was 25.4% (95% CI 18.1-33.4). Its prevalence was higher in patients without a left colic artery (LCA) (PP = 83.2%; 95% CI 70.4-93.1). The commonest origin for the AMCA was the superior mesenteric artery (PP = 87.9%; 95% CI 86.4-90.7). The AMCA shared a common trunk/gave rise to pancreatic branches in 23.1% of cases (95% CI 15.3-31.9).

CONCLUSION

The AMCA contributes to the vascularization of the splenic flexure in approximately 25% of individuals, and may be an important feeder artery to SFCs, especially in the absence of a LCA. Preoperative identification of this artery is important to ensure optimal surgery for SFC and minimize complications.

Mucosal blood flow in the remaining rectal stump is more affected by total than partial mesorectal excision in patients undergoing anterior resection: a key to understanding differing rates of anastomotic leakage?

Purpose

Anterior resection is the procedure of choice for tumours in the mid and upper rectum. Depending on tumour height, a total mesorectal excision (TME) or partial mesorectal excision (PME) can be performed. Low anastomoses in particular have a high risk of developing anastomotic leakage, which might be explained by blood perfusion compromise. A pilot study indicated a worse blood flow in TME patients in an open setting. The aim of this study was to further evaluate perianastomotic blood perfusion changes in relation to TME and PME in a predominantly laparoscopic context.

Method

In this prospective cohort study, laser Doppler flowmetry was used to evaluate the perianastomotic colonic and rectal perfusion before and after surgery. The two surgical techniques were compared in terms of mean differences of perfusion units using a repeated measures ANOVA design, which also enabled interaction analyses between type of mesorectal excision and location of measurement. Anastomotic leakage until 90 days after surgery was reported for descriptive purposes.

Results

Some 28 patients were available for analysis: 17 TME and 11 PME patients. TME patients had a reduced blood perfusion postoperatively compared to PME patients in the aboral posterior area (mean difference: −57 vs 18 perfusion units; p = 0.010). An interaction between mesorectal excision type and anterior/posterior location was detected at the aboral level (p = 0.007). Two patients developed a minor leakage, diagnosed after discharge.

Conclusion

Patients operated on using TME have a decreased blood flow in the aboral posterior quadrant of the rectum postoperatively compared to patients operated on using PME. This might explain differing rates of anastomotic leakage.

Trial registration

ClinicalTrials.gov Identifier: NCT02401100

Quantitative fluorescence angiography aids novice and experienced surgeons in performing intestinal resection in well-perfused tissue

Background

Anastomotic leakage (AL) after gastrointestinal resection is a devastating complication with huge consequences for the patient. As AL is associated with poor blood supply, tools for objective assessment of perfusion are in high demand. Indocyanine green angiography (ICG-FA) and quantitative analysis of ICG-FA (q-ICG) seem promising. This study aimed to investigate whether ICG-FA and q-ICG could improve perfusion assessment performed by surgeons of different experience levels.

Methods

Thirteen small bowel segments with a varying degree of devascularization, including two healthy sham segments, were constructed in a porcine model. We recruited students, residents, and surgeons to perform perfusion assessment of the segments in white light (WL), with ICG-FA, and after q-ICG, all blinded to the degree of devascularization.

Results

Forty-five participants fulfilled the study (18 novices, 12 intermediates, and 15 experienced). ICG and q-ICG helped the novices correctly detect the healthy bowel segments to experienced surgeons’ level. ICG and q-ICG also helped novice surgeons to perform safer resections in healthy tissue compared with normal WL. The relative risk (RR) of leaving ischemic tissue in WL and ICG compared with q-ICG, even for experienced surgeons was substantial, intermediates (RR = 8.9, CI95% [4.0;20] and RR = 6.2, CI95% [2.7;14.1]), and experienced (RR = 4.7, CI95% [2.6;8.7] and RR = 4.0, CI95% [2.1;7.5]).

Conclusion

Q-ICG seems to guide surgeons, regardless of experience level, to safely perform resection in healthy tissue, compared with standard WL. Future research should focus on this novel tool’s clinical impact.

Risk Factors for Anastomotic Leakage after Colorectal Surgery with Double-staple Technique Anastomosis: Impact of the Agatston Score

Objectives

Anastomotic leakage is associated with severe morbidity, mortality, and functional defects. Its risk factors remain unclear. However, blood perfusion may be a potential major risk factor. It has been reported that the Agatston score is an index for blood flow perfusion evaluation. Therefore, we evaluated the clinical indicators associated with anastomotic leakage, including the Agatston score, in patients who underwent colorectal surgery.

Methods

We retrospectively analyzed 147 patients who underwent elective colorectal surgery with the double-staple technique anastomosis for colorectal cancer between April 2015 and March 2020. The primary outcome was the presence or absence of anastomotic leakage. Univariate and multivariate analyses were employed to identify pre- and intraoperative risk factors.

Results

Of the 147 patients analyzed, anastomotic leakage occurred in 12 (8.16%). Male gender, history of angina and myocardial infarction, preoperative white blood cell count, the Agatston score, extent of bleeding, operation time, and intraoperative fluid volume were significantly related to a higher incidence of anastomotic leakage in univariate analysis. Multivariate analysis demonstrated that the incidence of anastomotic leakage was high in patients with a high Agatston score.

Conclusions

The Agatston score can predict the incidence of anastomotic leakage in patients following colorectal surgery. Thus, perioperative measures to prevent anastomotic leakage are recommended when a high Agatston score is observed. A prospective trial is required to demonstrate, with a high level of evidence, that the Agatston score can be useful as a risk score for anastomotic leakage following colorectal surgery.

Right paraduodenal hernia with extensive bowel gangrene treated with staged surgery: a Bogota bag followed by resection in a low-resource setting

We report a case of right paraduodenal hernia with strangulation of almost the entire small bowel at presentation. Since resection of all bowel of doubtful viability would have resulted in too little residual length to sustain life, a Bogota bag was fashioned using transparent plastic material from an urine drainage bag and the patient monitored intensively for 18 hours. At re-laparotomy, clear demarcation lines had formed with adequate length of viable bowel (100 cm) and resection with anastomosis was done with a good outcome on follow-up, 9 months after surgery. Our description of a rare cause of strangulated intestinal obstruction and a novel method of maximising length of viable bowel is reported for its successful outcome in a low-resource setting.

Damage control surgical management of combined small and large bowel injuries in penetrating trauma: Are ostomies still pertinent?

Hollow viscus injuries represent a significant portion of overall lesions sustained during penetrating trauma. Currently, isolated small or large bowel injuries are commonly managed via primary anastomosis in patients undergoing definitive laparotomy or deferred anastomosis in patients requiring damage control surgery. The traditional surgical dogma of ostomy has proven to be unnecessary and, in many instances, actually increases morbidity. The aim of this article is to delineate the experience obtained in the management of combined hollow viscus injuries of patients suffering from penetrating trauma. We sought out to determine if primary and/or deferred bowel injury repair via anastomosis is the preferred surgical course in patients suffering from combined small and large bowel penetrating injuries. Our experience shows that more than 90% of all combined penetrating bowel injuries can be managed via primary or deferred anastomosis, even in the most severe cases requiring the application of damage control principles. Applying this strategy, the overall need for an ostomy (primary or deferred) could be reduced to less than 10%.

Prospects of Intraoperative Multimodal OCT Application in Patients with Acute Mesenteric Ischemia

INTRODUCTION

Despite the introduction of increasingly multifaceted diagnostic techniques and the general advances in emergency abdominal and vascular surgery, the outcome of treatment of patients with acute impaired intestinal circulation remains unsatisfactory. The non-invasive and high-resolution technique of optical coherence tomography (OCT) can be used intraoperatively to assess intestine viability and associated conditions that frequently emerge under conditions of impaired blood circulation. This study aims to demonstrate the effectiveness of multimodal (MM) OCT for intraoperative diagnostics of both the microstructure (cross-polarization OCT mode) and microcirculation (OCT angiography mode) of the small intestine wall in patients with acute mesenteric ischemia (AMI).

METHODS AND PARTICIPANTS

A total of 18 patients were enrolled in the study. Nine of them suffered from AMI in segments II-III of the superior mesenteric artery (AMI group), whereby the ischemic segments of the intestine were examined. Nine others were operated on for adenocarcinoma of the colon (control group), thus allowing areas of their normal small intestine to be examined for comparison. Data on the microstructure and microcirculation in the walls of the small intestine were obtained intraoperatively from the side of the serous membrane using the MM OCT system (IAP RAS, Russia) before bowel resection. The MM OCT data were compared with the results of histological examination.

RESULTS

The study finds that MM OCT visualized the damage to serosa, muscularis externa, and blood vessels localized in these layers in 100% of AMI cases. It also visualized the submucosa in 33.3% of AMI cases. The MM OCT images of non-ischemic (control group), viable ischemic, and necrotic small intestines (AMI group) differed significantly across stratification of the distinguishable layers, the severity of intermuscular fluid accumulations, and the type and density of the vasculature.

CONCLUSION

The MM OCT diagnostic procedure optimally meets the requirements of emergency surgery. Data on the microstructure and microcirculation of the intestinal wall can be obtained simultaneously in real time without requiring contrast agent injections. The depth of visualization of the intestinal wall from the side of the serous membrane is sufficient to assess the volume of the affected tissues. However, the methodology for obtaining MM OCT data needs to be improved to minimize the motion artefacts generated in actual clinical conditions.

Fluorescence-guided cancer surgery-A new paradigm

Fluorescence-guided surgery is an emerging and promising operative adjunct to assist the surgeon in various aspects of oncosurgery, ranging from assessing perfusion, identification, and characterization of tumors and peritoneal metastases, mapping of lymph nodes/leaks, and assistance for fluorescence-guided surgery (FGS). This study aims to provide an overview of principles, currently available dyes, platforms, and surgical applications and summarizes the available literature on the utility of FGS with a focus on abdomino-thoracic malignancies.

Fluorescence-Based Quantification of Gastrointestinal Perfusion: A Step Towards an Automated Approach

Background: Qualitative fluorescence angiography (FA) provides insights into intestinal tissue perfusion, but today it is not yet accurate in predicting anastomotic leakage. To improve peroperative detection of impaired perfusion, quantified parameters should be investigated using a standardized method. The aim of this study was to develop a (semi)automated algorithm for comprehensive and convenient analysis of FA parameters. Materials and Methods: An analysis tool was developed for the extraction of quantified FA parameters. The start- and endpoint of intensity increase (T₀ and Tmax) were automatically detected in the intensity-time curves. Algorithm performance was measured against manual assignment of T₀ and Tmax by 9 independent observers in 18 in vivo generated test signals, using the intraclass correlation coefficient (ICC). Characteristics of parameter T1∕2 (time to 50% of maximal intensity) were analyzed in normally perfused small intestine of 32 subjects who underwent robotic laparoscopic surgery. Since ethical approval was not required under the Dutch law, the need for informed consent was waived. Results: Automated detection of T₀ and Tmax was successful in all subjects. Output of the algorithm had an excellent agreement with the median of the human observations: ICC = 0.95 (95% confidence interval: 0.86-0.96). Overall, T1∕2 had a median value of 5.1 (interquartile range = 2.4) seconds and a minimal and maximal value of 1.3 and 9.9 seconds, respectively. Conclusions: The presented method provided convenient data analysis in the search for effective FA quantification. Future research should expand the data to find adequate threshold values for peroperatively identifying insufficient perfusion and investigate the influence of physiological conditions.

Intraoperative perfusion assessment of the proximal colon by a visual grading system for safe anastomosis after resection in left-sided colorectal cancer patients

We aimed to evaluate the clinical feasibility of a new visual grading system. We included 50 patients who underwent resection of primary colorectal cancer. Before anastomosis, the marginal vessel was cut and the perfusion status was assessed by a visual grading system. The visual grading system is comprised of five grades according to the bleeding from the marginal vessel and is categorized into 4 groups: good (grade A and B), moderate (grade C), poor (grade D) and none (grade E). Colorectal anastomosis was performed only in the good and moderate groups. We compared postoperative outcomes between the good and moderate groups and analysed the factors affecting the perfusion grade. Among the patients, 48% were grade A, 12% were grade B, and 40% were grade C. There was no anastomotic leakage. Only one patient with grade C showed ischemic colitis and needed reoperation. Age was the only factor correlated with perfusion grade in multivariate analysis (OR 1.080, 95% CI 1.006-1.159, p = 0.034). The perfusion grades were significantly different between > 65 and < 65 year-old patients (> 65, A 29.2% B 12.5% C 58.3% vs. < 65, A 65.4% B 11.5% C 23.1%, p = 0.006). Our intraoperative perfusion assessment that uses a cutting method and a visual grading system is simple and useful for performing a safe anastomosis after colorectal resection. If the perfusion grade is better than grade C, an anastomosis can be performed safely. Age was found to be an important factor affecting the perfusion grade.

Assessing Ischemic Injury in Human Intestine Ex Vivo with Electrical Impedance Spectroscopy

Electrical impedance spectroscopy is a well-established tool for monitoring changes in the electrical properties of tissue. Most tissue and organ types have been investigated in various studies. As for the small intestine, there are several published studies conducted on pig and rat models. This study investigates the changes in passive electrical properties of the complete wall of the human intestine non-invasively during ischemia. We aim to use the passive electrical properties to assess intestinal viability. The bioimpedance measurements were performed using a two-electrode set-up with a Solartron 1260 Impedance/gain-phase analyser. The small intestinal samples were resected from patients who underwent pancreaticoduodenectomy. Impedance measurements were conducted following resection by placing the electrodes on the surface of the intestine. A voltage was applied across the intestinal sample and the measured electrical impedance was obtained in the ZPlot software. Impedance data were further fitted into a Cole model to obtain the Cole parameters. The P_y value was calculated from the extracted Cole parameters and used to assess the cell membrane integrity, thus evaluate the intestinal viability. Eight small intestinal segments from different patients were used in this study and impedance measurements were performed once an hour for a ten-hour period. One hour after resection, the impedance decreased, then increased the next two hours, before decreasing until the end of the experiment. For all the intestinal segments, the P_y values first increased and reached a plateau which lasted for 1 - 2 hours, before it decreased irreversibly. The time interval where P_y value reached the maximum is consistent with reported viable/non-viable limits from histological analysis.

The Use of Indocyanine Green Fluorescence Angiography in Pediatric Surgery: A Systematic Review and Narrative Analysis

Purpose: Indocyanine green fluorescence angiography (ICG-FA) is a validated non-invasive imaging technique used to assess tissue vascularization and guide intraoperative decisions in many surgical fields including plastic surgery, neurosurgery, and general surgery. While this technology is well-established in adult surgery, it remains sparsely used in pediatric surgery. Our aim was to systematically review and provide an overview of all available evidence on the perioperative use of indocyanine green fluorescence angiography in pediatric surgical patients. Methods: We conducted a systematic review with narrative synthesis in conformity with the PRISMA guidelines using PubMed, Medline, All EBM Reviews, EMBASE, PsycINFO, and CINAHL COMPLETE databases to identify articles describing the perioperative use of ICG-FA in pediatric patients. Two independent authors screened all included articles for eligibility and inclusion criteria. We extracted data on study design, demographics, surgical indications, indocyanine green dose, and perioperative outcomes. We developed a risk of bias assessment tool to evaluate the methodological quality of included studies. Results: Of 1,031 articles retrieved, a total of 64 articles published between 2003 and 2020 were included reporting on 664 pediatric patients. Most articles were case reports and case series (n = 36; 56%). No adverse events related to ICG-FA were reported in the included articles. Risk of bias was high. We did not conduct a meta-analysis given the heterogeneous nature of the populations, interventions, and outcome measures. A narrative synthesis is presented. Conclusion: Indocyanine green fluorescence angiography is a safe imaging technology and its use is increasing rapidly in pediatric surgical specialties. However, the quality of evidence supporting this trend currently appears low. Case-control and randomized trials are needed to determine the adequate pediatric dose and to confirm the potential benefits of ICG-FA in pediatric surgical patients. Systematic Review Registration: This study was registered on Prospero a priori, identifier: CRD42020151981.

Comparison of hyperspectral imaging and fluorescence angiography for the determination of the transection margin in colorectal resections-a comparative study

PURPOSE

One relevant aspect for anastomotic leakage in colorectal surgery is blood perfusion of both ends of the anastomosis. The clinical evaluation of this issue is limited, but new methods like fluorescence angiography with indocyanine green or non-invasive and contactless hyperspectral imaging have evolved as objective parameters for perfusion evaluation.

METHODS

In this prospective, non-randomized, open-label and two-arm study, fluorescence angiography and hyperspectral imaging were compared in 32 consecutive patients with each other and with the clinical assessment by the surgeon. After preparation of the bowel and determination of the surgical resection line, the tissue was evaluated with hyperspectral imaging for 5 min before and after cutting the marginal artery and assessed by 6 hyperspectral pictures followed by fluorescence angiography with indocyanine green.

RESULTS

In 30 of 32 patients, the image data could be evaluated and compared. Both methods provided a comparable borderline between well-perfused and poorly perfused tissue (p = 0.704). In 15 cases, the surgical resection line was shifted to the central position due to the imaging. The border zone was sharper in fluorescence angiography and best assessed 31 s after injection. With hyperspectral imaging, the border zone was visualized wider and with more differences between proximal and distal border.

CONCLUSION

Hyperspectral imaging and fluorescence angiography provide similar results in determining the perfusion border. Both methods allow a good and safe visualization of the blood perfusion at the central resection margin to create a well-perfused anastomosis.

TRIAL REGISTRATION

This study was registered at Clinicaltrials.gov ( NCT04226781 ) on January 13, 2020.

Laser Doppler Flowmetry and Visible Light Spectroscopy of the Gastric Tube During Minimally Invasive Esophagectomy

Introduction

Ischemia is considered as the main reason for thoracic gastroesophageal anastomotic leaks after esophagectomy. Microcirculatory monitoring with laser Doppler flowmetry and visible light spectroscopy may provide valuable intraoperative real-time information about the gastric tube’s tissue perfusion and circulation.

Patients and Methods

Ten patients with esophageal cancer operated with minimally invasive esophagectomy participated in this single-center, prospective, observational pilot study. A single probe with laser Doppler flowmetry and visible light spectroscopy was used to perform transserosal microcirculation assessment of the gastric tube at predefined anatomical sites during different operation phases. Group comparison and changes were evaluated using the paired sample t-test.

Results

A reduction in StO2 was found at all measuring sites after the gastric tube formation compared with the baseline measurements. The mean StO2 reduction from baseline to gastric tube formation and after anastomosis was 16% (range 4%–28%) and 42% (range, 35%–52%), respectively. A statistically significant increase in the rHb concentration, representing venous congestion, was detected at the most cranial part of the gastric tube (P = 0.04). Three patients developed anastomotic leaks.

Conclusion

Intraoperative real-time laser Doppler flowmetry and visible light spectroscopy are feasible and may provide insight to microcirculatory changes in the gastric tube and at the anastomotic site. Patients with anastomotic leaks seem to have critical local tissue StO2 reduction and venous congestion that should be further evaluated in studies with larger sample sizes.

Validation of quantitative assessment of indocyanine green fluorescent imaging in a one-vessel model

Objectives

Evaluation of intestinal perfusion remains subjective and depends on the surgeon´s individual experience. Intraoperative quality assessment of tissue perfusion with indocyanine green (ICG) fluorescence using a near-infrared camera system has been described in different ways and for different indications. The aim of the present study was to evaluate fluorescent imaging (FI) in the quantitative assessment of intestinal perfusion in a gastric tube model in pigs and to compare the results to results obtained with florescent microspheres (FM), the gold standard for tissue perfusion.

Methods

Seven pigs (56.0±3.0 kg), both males and females, underwent gastric tube formation after transection and ligation of the gastric arteries, except the right gastroepiploic artery, to avoid collateral blood flow.

After baseline assessment (T0), hypotension (T1) was induced by propofol (Karampinis et al 2017) (< 60 mmHg). Then, propofol was paused to obtain normotension (T2, Mean arterial pressure (MAP) 60–90 mmHg). Finally, hypertension (T3, MAP>90 mmHg) was induced by norepinephrine.

Measurements were performed in three regions of interest (ROIs) under standardized conditions: the fundus (D1), corpus (D2), and prepyloric area (D3). Hemodynamic parameters and transit-time flow measurement (TTFM) in the right gastroepiploic artery were continuously assessed. FI, FM and the partial pressure of tissue oxygen (TpO₂) were quantified in each ROI.

Results

The study protocol could successfully be performed during stable hemodynamics. Flow in the gastroepiploic artery measured by transit time flow measurement (TTFM) was related to hemodynamic changes between the measurements, indicating improved blood flow with increasing MAP. The distal part of the gastric tube (D1) showed significantly (p<0.05) impaired perfusion compared to the proximal parts D3 and D2 using FM. ICG-FI also showed the highest values in D3 and the lowest values in D1 at all hemodynamic levels (T1-T3; p<0,05).

Conclusion

Visual and quantitative assessment of gastric tube perfusion is feasible in an experimental setting using ICG-FI. This might be a promising tool for intraoperative assessment during visceral surgery in the future.

Simultaneous computer-assisted assessment of mucosal and serosal perfusion in a model of segmental colonic ischemia

BACKGROUND

Fluorescence-based enhanced reality (FLER) enables the quantification of fluorescence signal dynamics, which can be superimposed onto real-time laparoscopic images by using a virtual perfusion cartogram. The current practice of perfusion assessment relies on visualizing the bowel serosa. The aim of this experimental study was to quantify potential differences in mucosal and serosal perfusion levels in an ischemic colon segment.

METHODS

An ischemic colon segment was created in 12 pigs. Simultaneous quantitative mucosal and serosal fluorescence imaging was obtained via intravenous indocyanine green injection (0.2 mg/kg), using two near-infrared camera systems, and computer-assisted FLER analysis. Lactate levels were measured in capillary blood of the colonic wall at seven regions of interest (ROIs) as determined with FLER perfusion cartography: the ischemic zone (I), the proximal and distal vascularized areas (PV, DV), and the 50% perfusion threshold proximally and distally at the mucosal and serosal side (P50M, P50S, D50M, D50S).

RESULTS

The mean ischemic zone as measured (mm) for the mucosal side was significantly larger than the serosal one (56.3 ± 21.3 vs. 40.8 ± 14.9, p = 0.001) with significantly lower lactate values at the mucosal ROIs. There was a significant weak inverse correlation between lactate and slope values for the defined ROIs (r = - 0.2452, p = 0.0246).

CONCLUSIONS

Mucosal ischemic zones were larger than serosal zones. These results suggest that an assessment of bowel perfusion from the serosal side only can underestimate the extent of ischemia. Further studies are required to predict the optimal resection margin and anastomotic site.

Does preoperative enhanced CT predict requirement of intestinal resection in the patients with incarcerated myopectineal hernias containing small bowel?

PURPOSE

Bowel wall enhancement on CT imaging is considered one of the useful features for the prediction of the presence of irreversible ischemic change in patients with small bowel obstruction. However, the applicability of CT imaging in patients with incarcerated hernias has not been investigated in detail. The aim of this retrospective study was to evaluate the feasibility of preoperative CT findings for the prediction of the presence of irreversible ischemic change in patients with incarcerated hernias containing small bowel.

METHODS

Included in this study were 76 patients who underwent surgery for preoperatively diagnosed incarcerated hernias containing small bowel (27 inguinal hernias, 37 femoral hernias and 12 obturator hernias) at our hospital between January 2011 and June 2020. The preoperative clinicoradiological features were compared between the groups, and predictors for intestinal resection were evaluated.

RESULTS

Nineteen patients required intestinal resection (Resection group), and the other 57 patients did not require intestinal resection (Nonresection group). Multivariate analyses revealed that age ≥ 80 years (p = 0.018, odds ratio = 6.604) and the absence of bowel wall enhancement (p = 0.032, odds ratio = 51.200) were independent predictors for intestinal resection. In resected specimens, all patients with an absence of bowel wall enhancement on preoperative enhanced CT had ischemic changes extending beyond the muscularis propria.

CONCLUSIONS

Preoperative enhancement CT yields useful information for the prediction of the presence of irreversible ischemic change in patients with incarcerated hernias containing small bowel.

Evaluation of jejunal microvasculature of healthy anesthetized dogs with sidestream dark field video microscopy

OBJECTIVE

To determine the feasibility of sidestream dark field (SDF) video microscopy for the evaluation of the jejunal microvasculature of healthy dogs.

ANIMALS

30 healthy sexually intact female shelter dogs anesthetized for ovariohysterectomy.

PROCEDURES

Preoperative physical and clinicopathologic assessments were performed to confirm health status. Then healthy dogs were anesthetized, and the abdomen was incised at the ventral midline for ovariohysterectomy and jejunal microvasculature evaluation. An SDF video microscope imaged the microvasculature of 2 sites of a portion of the jejunum, and recorded videos were analyzed with software capable of quantitating parameters of microvascular health. Macrovascular parameters (heart rate, respiratory rate, and hemoglobin oxygen saturation) were also recorded during anesthesia.

RESULTS

Quantified jejunal microvascular parameters included valid microvascular density (mean ± SD, 251.72 ± 97.10 μm/mm), RBC-filling percentage (66.96 ± 8.00%), RBC column width (7.11 ± 0.72 μm), and perfused boundary region (2.17 ± 0.42 μm). The perfused boundary region and RBC-filling percentage had a significant negative correlation. Strong to weak positive correlations were noted among the perfused boundary regions of small-, medium-, and large-sized microvessels. No significant correlations were identified between microvascular parameters and age, body weight, preoperative clinicopathologic results, or macrovascular parameters.

CONCLUSIONS AND CLINICAL RELEVANCE

Interrogation of the jejunal microvasculature of healthy dogs with SDF video microscopy was feasible. Results of this study indicated that SDF video microscopy is worth additional investigation, including interrogation of diseased small intestine in dogs.

Complicated Diverticular Disease

The modern management of colonic diverticular disease involves grouping patients into uncomplicated or complicated diverticulitis, after which the correct treatment paradigm is instituted. Recent controversies suggest overlap in management strategies between these two groups. While most reports still support surgical intervention for the treatment of complicated diverticular disease, more data are forthcoming suggesting complicated diverticulitis does not merit surgical resection in all scenarios. Given the significant risk for complication in surgery for diverticulitis, careful attention should be paid to patient and procedure selection. Here, we define complicated diverticulitis, discuss options for surgical intervention, and explain strategies for avoiding operative pitfalls that result in early and late postoperative complications.

In Vivo Bioluminescence Imaging for Targeting Acute Hypoxic/Ischemic Small Intestine with Engineered Salmonella typhimurium

This study aimed at investigating the feasibility of bioluminescence imaging (BLI) with engineered Salmonella typhimurium (ΔppGpp S. typhimurium) for visualizing acute hypoxic/ischemic bowels. At the start of 12- or 24-h reperfusion, ΔppGpp S. typhimurium was injected into the lateral tail veins of rats in which three segments of the small intestine were respectively subjected to 2, 3, and 4 h of ischemia. BLI and magnetic resonance imaging were performed at each reperfusion time point. Bioluminescence was exclusively detected in the hypoxic/ischemic segment of the intestine, showing the ability of ΔppGpp S. typhimurium to specifically target and proliferate in a hypoxic/ischemic area. Serial monitoring of these rat models revealed a progressive increase in bacterial bioluminescence in the ischemic intestines in conjunction with viable bacterial counts. The viable bacterial counts were positively correlated with lactate dehydrogenase levels after 24 h of reperfusion following 3 or 4 h of ischemia as well as interleukin-6 levels after 24 h of reperfusion following 4 h of ischemia. Our findings demonstrated that BLI was able to detect the acute hypoxic/ischemic bowel via monitoring of the distribution, internalization, and activity of administered ΔppGpp S. typhimurium. These findings may be useful for the early diagnosis of ischemic bowel disease.

Assessment of intraoperative use of indocyanine green fluorescence imaging on the incidence of anastomotic leakage after rectal cancer surgery: a PRISMA-compliant systematic review and meta-analysis

BACKGROUND

The current data on the intraoperative use of indocyanine green (ICG) fluorescence imaging to reduce the anastomotic leak (AL) rate in rectal cancer surgery remain controversial. The aim of this systematic review and meta-analysis was to evaluate the efficacy of ICG fluorescence imaging in decreasing the AL rate after rectal cancer surgery.

METHODS

Studies comparing ICG fluorescence imaging with standard care in patients with rectal cancer were systematically searched from PubMed, Embase, Web of Science and Cochrane Library through January 2020. The current meta-analysis was performed according to the preferred reporting items for systematic review and meta-analysis guidelines. A pooled analysis was performed for the available data regarding the baseline features, AL rate and other surgical outcomes. RevMan version 5.3 software was used for the present meta-analysis.

RESULTS

Nine studies with a total of 2088 patients with rectal cancer (926 in the ICG group and 1162 in the control group) were included in the present study. In the pooled analysis, the available patient and tumour-related baseline data were all comparable and without significant heterogeneity. In the present pooled analysis, the AL rate in the ICG group was significantly lower (OR 0.34; 95% CI 0.22-0.52; p < 0.0001) than that in the control group. Additionally, intraoperative use of ICG was associated with a decreased overall complication rate (OR 0.57; 95% CI 0.42-0.78; p = 0.0003) and reduced reoperation rate (OR 0.26; 95% CI 0.08-0.86; p = 0.03) in patients who had rectal cancer surgery.

CONCLUSIONS

The present study demonstrated the superiority of the intraoperative use of ICG in reducing the AL rate. However, considering the limitations of the included studies, more high-quality prospective studies and randomized controlled trials are needed.

A study investigating the perfusion of colorectal anastomoses using fluorescence angiography: results of the FLAG randomized trial

AIM

Our aim was to evaluate the efficacy of indocyanine green (ICG) fluorescence angiography (FA) in reducing the incidence of anastomotic leakage (AL) following colorectal anastomosis.

METHOD

A single-centre randomized trial was undertaken between 2018 and 2019. Those patients who underwent a stapled colorectal anastomosis were randomized 1:1 for ICG FA versus visual clinical assessment of blood perfusion of the anastomosed colon and rectal stump (non-ICG FA group). The primary end-point was to assess whether ICG FA was associated with a reduction in the incidence of AL. Secondary outcomes were the rate of postoperative complications and change in the level of bowel resection.

RESULTS

A total of 380 patients undergoing sigmoid and rectal resection were enrolled. After randomization, three patients were excluded. The results of 377 cases were available for analysis; 187 had ICG FA and 190 were in the non-ICG FA group. ICG FA identified impaired blood perfusion of the colon in 36 (19%) cases. An AL (grade A, B or C) developed in 48 patients: 17 (9.1%) in the ICG FA group and 31 (16.3%) in the non-ICG FA group (P = 0.04). ICG FA did not decrease the rate of AL of high anastomoses (9-15 cm from the anal verge), at 1.3% vs 4.6% in the non-ICG FA group (P = 0.37). In contrast, a decrease in AL rate was found for low (4-8 cm) colorectal anastomoses (14.4% in ICG FA vs 25.7% in the non-ICG FA group; P = 0.04).

CONCLUSION

ICG FA is associated with a reduction in AL following low anterior resection.

Quantification of fluorescence angiography: Toward a reliable intraoperative assessment of tissue perfusion - A narrative review

BACKGROUND

Accurate intraoperative assessments of tissue perfusion are essential in all forms of surgery. As traditional methods of perfusion assessments are not available during minimally invasive surgery, novel methods are required. Here, fluorescence angiography with indocyanine green has shown promising results. However, to secure objective and reproducible assessments, quantification of the fluorescent signal is essential (Q-ICG). This narrative review aims to provide an overview of the current status and applicability of Q-ICG for intraoperative perfusion assessment.

RESULTS

Both commercial and custom Q-ICG software solutions are available for intraoperative use; however, most studies on Q-ICG have performed post-operative analyses. Q-ICG can be divided into inflow parameters (ttp, t0, slope, and T_1/2max) and intensity parameters (Fmax, PI, and DR). The intensity parameters appear unreliable in clinical settings. In comparison, inflow parameters, mainly slope, and T_1/2max have had superior clinical performance.

CONCLUSION

Intraoperative Q-ICG is clinically available; however, only feasibility studies have been performed, rendering an excellent usability score. Q-ICG in a post-operative setting could detect changes in perfusion following a range of interventions and reflect clinical endpoints, but only if based on inflow parameters. Thus, future studies should include the methodology outlined in this review, emphasizing the use of inflow parameters (slope or T_1/2max), a mass-adjusted ICG dosing, and a fixed camera position.

Perioperative Microcirculatory Changes Detected with Gastroscopy Assisted Laser Doppler Flowmetry and Visible Light Spectroscopy in Patients with Median Arcuate Ligament Syndrome

Purpose

Physiological tests may aid in diagnosing median arcuate ligament syndrome (MALS). MALS is a symptomatic compression of the celiac artery causing symptoms similar to chronic mesenteric ischemia (CMI) of atherosclerotic etiology. Simultaneous use of visible light spectroscopy (VLS) and laser doppler flowmetry (LDF) during upper endoscopy may detect microcirculatory changes in these patients.

Patients and Methods

In a single-center, prospective comparative cohort, 25 patients were evaluated for MALS. Patients with a consensus diagnosis of MALS (n=15) underwent a gastroscopy assisted, transmucosal microcirculatory assessment with LDF and VLS. Results were compared to individuals with normal intestinal circulation (n=38) evaluated with duplex ultrasonography, and to patients with chronic mesenteric ischemia (n=32). Treatment response was evaluated clinically at 1, 3, 6, and 12 months, and with ultrasound, VLS and LDF at three months. Health-related quality of life (QoL) was assessed with Euroqol (EQ-5D-5L), preoperatively, and 12 months postoperatively.

Results

Preoperative mean transmucosal oxygen saturation was significantly lower in patients with MALS (SO₂ 76±6), as compared to healthy individuals (SO₂ 81±4), p=0.02. An overall significant improvement in SO₂ after surgical decompression of the celiac artery was found (SO₂ 81±3.7, p=0.05). Eleven (92%) patients with clinical improvement after laparoscopic decompression had a definitive diagnosis of MALS. Median follow-up was 18 months (4–24 months). Four of the five dimensions investigated with EQ-5D-5L improved.

Conclusion

VLS detected a significantly lower baseline transmucosal SO₂ in patients with MALS as compared to control subjects with normal intestinal circulation. An improvement in SO₂ after laparoscopic decompression was found, supporting a possible ischemic etiology in our patient population.

A Novel Parameter Identified Using Indocyanine Green Fluorescence Angiography may Contribute to Predicting Anastomotic Leakage in Gastric Cancer Surgery

BACKGROUND

Anastomotic leak is one of the most serious postoperative complications, and intraoperative adequate perfusion plays a key role in preventing its development in gastric cancer surgery. This study aimed to investigate the relationships between anastomotic leak and the parameters defined by an assessment of intraoperative anastomotic perfusion using a near-infrared indocyanine green (ICG) fluorescence system and to evaluate the usefulness of this ICG fluorescence assessment in gastric cancer surgery.

METHODS

We retrospectively reviewed data of 100 patients who underwent gastric cancer surgery. In a visual assessment based on fluorescence intensity, we classified ICG fluorescence image patterns as homogeneous, heterogeneous, or faint. In a chronological assessment, the first or second time point of ICG fluorescence appearance on one or the other side of the anastomosis was defined as FT or ST, respectively. The time difference in ICG fluorescence appearance between FT and ST was defined as TD. The relationships between anastomotic leak and the evaluated clinical factors, including the parameters identified by the ICG fluorescence assessment, were evaluated using univariate or multivariate analysis.

RESULTS

Although no signs of leak were found by surgeons' subjective judgments, four patients developed postoperative anastomotic leak of Clavien-Dindo grade III or IV. Multivariate analysis revealed that TD was an independent predictor of anastomotic leak (odds ratio 35.361, 95% confidence interval 1.489-839.923, p = 0.027).

CONCLUSIONS

A novel parameter identified using near-infrared ICG fluorescence assessment may be useful to predict anastomotic leak in gastric cancer surgery.

TRIAL REGISTRATION

UMIN Clinical Trials Registry: #UMIN000030747 ( https://www.umin.ac.jp/ctr/index.htm ).

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.

The impact of near-infrared angiography and proctoscopy after rectosigmoid resection and anastomosis performed during surgeries for gynecologic malignancies

OBJECTIVES

Reducing anastomotic leak rates after rectosigmoid resection and anastomosis is a priority in patients undergoing gynecologic oncology surgery. Therefore, we investigated the implications of performing near-infrared angiography (NIR) via proctoscopy to assess anastomotic perfusion at the time of rectosigmoid resection and anastomosis.

METHODS

We identified all patients who underwent rectosigmoid resection and anastomosis for a gynecologic malignancy between January 1, 2013 and December 31, 2018. NIR proctoscopy was assessed via the PINPOINT Endoscopic Imaging System (Stryker).

RESULTS

A total of 410 patients were identified, among whom NIR was utilized in 133 (32.4%). There were no statistically significant differences in age, race, BMI, type of malignancy, surgery, histology, FIGO stage, hypertension, diabetes, or preoperative chemotherapy between NIR and non-NIR groups. All cases of rectosigmoid resection underwent stapled anastomosis. The anastomotic leak rate was 2/133 (1.5%) in the NIR cohort compared with 13/277 (4.7%) in the non-NIR cohort (p = 0.16). Diverting ostomy was performed in 9/133 (6.8%) NIR and 53/277 (19.9%) non-NIR patients (p < 0.001). Postoperative abscesses occurred in 8/133 (6.0%) NIR and 44/277 (15.9%) non-NIR patients (p = 0.004). The NIR cohort had significantly fewer post-operative interventional procedures (12/133, 9.0% NIR vs. 55/277, 19.9% non-NIR, p = 0.006) and significantly fewer 30-day readmissions (14/133, 10.5% NIR vs. 61/277, 22% non-NIR, p = 0.004).

CONCLUSIONS

NIR proctoscopy is a safe tool for assessing anastomotic rectal perfusion after rectosigmoid resection and anastomosis, with a low anastomotic leak rate of 1.5%. Its potential usefulness should be evaluated in randomized trials in patients undergoing gynecologic cancer surgery.

The Pathophysiology of Small Intestinal Foreign Body Obstruction and Intraoperative Assessment of Tissue Viability in Dogs: A Review

Small intestinal foreign body obstructions occur commonly in dogs, accounting for 80% of all canine intestinal obstructions. Such obstructions induce local aberrations in secretion, absorption, and intestinal motility that can precipitate devastating systemic consequences, including a systemic inflammatory response, sepsis, and multiorgan dysfunction. Radiographic diagnosis is poorly sensitive relative to ultrasonography for diagnosing the presence of obstructive foreign material. Emergent surgical intervention is indicated for dogs with obstructive foreign material due to an inability to assess the degree of compromise of the intestinal wall that may precipitate intestinal perforation and to mitigate progression of life-threatening electrolyte and acid-base imbalances secondary to sequestration and emesis. Intraoperatively, an enterotomy or resection and anastomosis may be required to remove the obstructive material. A number of subjective and objective techniques for assessing the viability of intestinal tissue have been described due to the poor accuracy associated with surgeon assessment of color, peristalsis, pulsation, bleeding, and mural thickness alone. Such techniques have the potential to alter the surgeon's decision-making regarding performance of an enterotomy or resection and anastomosis, potentially reducing morbidity associated with 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.

Laparoscopic surgery for two patients with strangulated transomental hernias

Background

Transomental hernias are a rare type of internal hernia. We report two cases of successful cases of laparoscopic repair. One required laparotomy due to concern for intestinal viability.

Case presentation

The first patient was a 67-year-old man who presented with abdominal pain and vomiting. He had no history of laparotomy or abdominal injury. Computed tomography suggested small bowel obstruction and possible intestinal strangulation. Emergent laparoscopy found approximately 200 cm of small bowel was strangulated around the greater omentum. The strangulation was released laparoscopically, but because of the color of the strangulated bowel, laparotomy was performed to evaluate viability. The involved portion of intestine was not resected. The patient experienced transient postoperative paralytic ileus and was discharged on postoperative day 14. The second patient was a 56-year-old man who presented with abdominal pain. Abdominal computed tomography revealed dilatation of the small intestine and a closed loop suggesting ileus due to intestinal strangulation. An emergency laparoscopy found a transomental hernia, and the strangulation was released laparoscopically. Recovery was uneventful, and the patient was discharged on postoperative day 6.

Conclusion

Transomental hernia can be successfully treated laparoscopically. In cases where bowel viability is a concern, laparotomy should not be hesitated.

The problem of colorectal anastomosis safety

INTRODUCTION

Anastomotic leakage (AL) remains one of the most threatening complications in colorectal surgery with the incidence of up to 20%. The aim of the study is to evaluate the safety and feasibility of novel - trimodal intraoperative colorectal anastomosis testing technique.

METHODS AND ANALYSIS

This multi-center prospective cohort pilot study will include patients undergoing colorectal anastomosis formation below 15 cm from the anal verge. Trimodal anastomosis testing will include testing for blood supply by ICG fluorescence trans-abdominally and trans-anally, testing of mechanical integrity of anastomosis by air-leak and methylene blue leak tests and testing for tension. The primary outcome of the study will be AL rate at day 60. The secondary outcomes will include: the frequency of changed location of bowel resection; ileostomy rate; the rate of intraoperative AL; time, taken to perform trimodal anastomosis testing; postoperative morbidity and mortality; quality of life.

DISCUSSION

Trimodal testing of colorectal anastomosis may be a novel and comprehensive way to investigate colorectal anastomosis and to reveal insufficient blood supply and integrity defects intraoperatively. Thus, prevention of these two most common causes of AL may lead to decreased rate of leakage.

STUDY REGISTRATION

Clinicaltrials.gov (https://clinicaltrials.gov/): NCT03958500, May, 2019.