Estimation of microvascular perfusion after esophagectomy: a quantitative model of dynamic fluorescence imaging

Right gastroepiploic artery length determined anastomotic leakage after minimally invasive esophagectomy for esophageal cancer: a prospective cohort study

BACKGROUND

This prospective cohort study, conducted at a high-volume esophageal cancer center from July 2019 to July 2022, aimed to investigate the link between the right gastroepiploic artery (RGEA) length and anastomotic leakage (AL) rates following minimally invasive esophagectomy (MIE). Real-world data on stomach blood supply in the Chinese population were examined.

MATERIALS AND METHODS

A total of 516 cases were enrolled, categorized into two groups based on the Youden index-determined optimal cut-off value for the relative length of RGEA (length of RGEA/length of gastric conduit, 64.69%) through ROC analysis: Group SR (short RGEA) and Group LR (long RGEA). The primary observation parameter was the relationship between AL incidence and the ratio of direct blood supply from RGEA. Secondary parameters included the mean length of the right gastroepiploic artery, greater curvature, and the connection type between right and left gastroepiploic vessels. Patient data were prospectively recorded in electronic case report forms.

RESULTS

The study revealed median lengths of 43.60 cm for greater curvature, 43.16 cm for the gastric conduit, and 26.75 cm for RGEA. AL, the most common postoperative complication, showed a significant difference between groups (16.88 vs. 8.84%, P =0.01). Multivariable binary logistic regression identified Group SR and LR (odds ratio: 2.651, 95% CI: 1.124-6.250, P =0.03) and Neoadjuvant therapy (odds ratio: 2.479, 95% CI: 1.374-4.473, P =0.00) as independent predictors of AL.

CONCLUSIONS

The study emphasizes the crucial role of RGEA length in determining AL incidence in MIE for esophageal cancer. Preserving RGEA and fostering capillary arches between RGEA and LGEA are recommended strategies to mitigate AL risk.

Intraoperative fluorescence imaging in esophagectomy and its application to the robotic platform: a narrative review

Background and Objective

Robotic-assisted esophagectomy is an approach to minimally invasive esophagectomy (MIE) that has demonstrated equivalent or improved outcomes relative to open and other minimally invasive techniques. The robotic approach also allows unique opportunities to improve complications following esophagectomy through use of enhanced visualization tools, including intraoperative fluorescence imaging. In this review, we summarize the specific uses of intraoperative fluorescence imaging as an adjunct tool during esophagectomy and discuss its application to the robotic platform.

Methods

A literature search was conducted via PubMed in February 2022 with the following keywords: esophagectomy, esophageal cancer, infrared, near-infrared (NIR) and fluorescence. Peer-reviewed academic journal articles published in English between 2000 and 2021 were included.

Key Content and Findings

There is a growing body of literature evaluating the use of intraoperative fluorescence imaging in robotic-assisted esophagectomy. This includes assessment of gastric conduit perfusion, including feasibility, creation of the gastroesophageal anastomosis, and qualification of perfusion, along with lymphatic mapping and identification of critical anatomy. These tools are uniquely leveraged using the robotic platform to standardize and quantify key technical aspects of the operation.

Conclusions

Intraoperative fluorescence imaging provides the opportunity to assess perfusion and identify anatomy for more precise and patient-specific dissection and reconstruction. Among all the operative techniques for esophagectomy, robotic-assisted esophagectomy is uniquely suited to utilize these imaging modalities to optimize outcomes and minimize risk associated with esophagectomy.

Application of Indocyanine Green Enhanced Fluorescence in Esophageal Surgery: A Mini Review

Despite recent technological innovations and the development of minimally invasive surgery, esophagectomy remains an operation burdened with severe postoperative complications. Fluorescence imaging, particularly using indocyanine green (ICG), offers the ability to address a number of issues faced during esophagectomy. The three main indications for the intraoperative use of ICG during esophagectomy are visualization of conduit vascular supply, allow identification of sentinel nodes and visualization of the thoracic duct. The purpose of this mini review is to present an overview of current practice in fluorescence imaging utilizing ICG during esophagectomy, as well as to demonstrate how this technology can guide lymphadenectomy and reduce surgical morbidity such as anastomotic leaking and chylothorax.

Bladder augmentation from an insider's perspective: a review of the literature on microcirculatory studies

Augmentation cystoplasty is an exemplary multiorgan intervention in urology which is particularly associated with microvascular damage. Our aim was to review the available intravital imaging techniques and data obtained from clinical and experimental microcirculatory studies involving the most important donor organs applied in bladder augmentation. Although numerous direct or indirect methods are available to assess the condition of microvessels the implementation of microcirculatory diagnostic methods in humans is still challenging and the assessment of organ microcirculation in the operating theatre has limitations. Nevertheless, preclinical studies generally report good internal validity and although prospective human protocols with reduced variability are needed, a possible positive impact of microcirculatory diagnostics on the clinical outcomes of urologic surgery can be anticipated.

Indocyanine green fluorescence imaging for evaluating blood flow in the reconstructed conduit after esophageal cancer surgery

We investigated the effectiveness of indocyanine green (ICG) fluorescence blood flow imaging of the gastric conduit to evaluate anastomotic leakage after esophagectomy. We identified 19 articles using the PRISMA standard for systematic reviews. The more recent studies reported attempts at objective quantification of ICG fluorescence imaging, rather than qualitative assessment. Anastomotic leakage after esophagectomy occurred in 0-33% of the patients who underwent ICG fluorescence imaging. According to the six studies that compared the incidence of anastomotic leakage in the ICG group and the control group, it ranged from 0 to 18.3% in the ICG group and from 0 to 25.2% in the control group, respectively. Overall, the incidence of anastomotic leakage in the ICG group (8.4%) was lower than that in the control group (18.5%). Although the incidence of anastomotic leakage was as high as 43.1% in patients who did not undergo any intraoperative intervention for poor blood flow, it was only 24% in patients who underwent intraoperative intervention. This systematic review revealed that ICG fluorescence imaging may be a crucial adjunctive tool for reducing anastomotic leakage after esophagectomy, suggesting that it should be performed during esophageal reconstruction.

Quantitative change of perfusion in gastric tube reconstruction by sidestream dark field microscopy (SDF) after esophagectomy, a prospective in-vivo cohort study

BACKGROUND

Anastomotic leakage is one of the most severe complications in patients undergoing esophagectomy with gastric tube reconstruction. Transection of the left gastric and gastro-epiploic artery and vein results in compromised perfusion which is seen as the major contributing factor for anastomotic dehiscence. The main objective of this prospective, observational, in-vivo pilot study is to microscopically evaluate gastric tube perfusion with Sidestream Darkfield Microscopy (SDF).

METHODS

Intra-operative microscopic images of gastric-microcirculation were obtained with SDF directly after reconstruction in 22 patients. Quantitative perfusion related parameters were: velocity, Microvascular Flow Index(MFI), Total Vessel Density(TVD), Perfusion Vessel Density(PVD), Proportion of Perfused Vessels(PPV) and De Backer Score(DBS). Dedicated software was used to assess parameters predictive for compromised perfusion.

RESULTS

SDF was feasible to accurately visualize and evaluate microcirculation in all patients. Velocity(μm/sec) was significantly decreased towards the fundus (p = 0.001). MFI, PVD and PVD were decreased distal of the watershed - between the right and left gastro-epiploic artery and vein - and in the fundus, compared to the base of the gastric tube(p = 0.0002). No differences in TVD and DBS were observed; because of vessel-dilation in the fundus-area. This suggests that venous congestion results in comprised inflow of oxygen rich blood and plays a role in the development of ischaemia.

CONCLUSION

We present quantitative perfusion imaging with SDF of the gastric tube. Velocity, MFI, TVD and PPV are accurate parameters to observe perfusion decrease. Also, venous congestion is visible in the fundus, suggesting an important role in the development of ischaemia. These parameters could allow early risk stratification, and, potentially, can accomplish a reduction in anastomotic leakage.

Perfusion speed of indocyanine green in the stomach before tubulization is an objective and useful parameter to evaluate gastric microcirculation during Ivor-Lewis esophagectomy

BACKGROUND

Anastomotic leakage (AL) during Ivor-Lewis esophagectomy (ILE), owing to gastric conduit (GC) ischemia, is a serious complication. Measurement parameters during intraoperative ICG fluorescence angiography (ICG-FA) are unclear. We aimed to identify objective ICG-FA parameters associated with AL.

STUDY DESIGN

Patients > 18 years with an indication for ILE were enrolled. ICG-FA was performed at the abdominal and thoracic stage, and data, such as time of fluorescence appearance, speed of ICG perfusion, quality of GC perfusion (good, poor, ischemic), blood pressure, baseline patient characteristics, GC dimensions, and other intraoperative parameters were collected. On postoperative day 4 to 6, Gastrografin swallow radiography was performed. AL development was classified based on the Clavien-Dindo and SISG severity classifications. Univariate analysis with a 95% confidence level (p < 0.05) was performed. Factors with p < 0.05 were included in the multivariate analysis.

RESULTS

100 patients were enrolled. During ICG-FA, evaluation of subjective perfusion was a very specific test (94.1%) with good negative predictive value (NPV 71.9%, p 0.034), but not powerful enough to detect patients at risk of leak (sensibility 21.8%, PPV 63.6%). The GC perfusion speed (cm/s) after gastric vascular isolation and before tubulization showed a significant association with AL (p < 0.003). Median arterial blood pressure in the thoracic stage (p < 0.001) or use of inotropic (p < 0.033) was associated with AL development.

CONCLUSION

GC perfusion speed at ICG-FA is an objective parameter that could predict AL risk. Other results emphasize the importance of the microcirculation in the development of AL.

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.

Comparison of Optical Imaging Techniques to Quantitatively Assess the Perfusion of the Gastric Conduit during Oesophagectomy

In this study, four optical techniques—Optical Coherence Tomography, Sidestream Darkfield Microscopy, Laser Speckle Contrast Imaging, and Fluorescence Angiography (FA)—were compared on performing an intraoperative quantitative perfusion assessment of the gastric conduit during oesophagectomy. We hypothesised that the quantitative parameters show decreased perfusion towards the fundus in the gastric conduit and in patients with anastomotic leakage. In a prospective study in patients undergoing oesophagectomy with gastric conduit reconstruction, measurements were taken with all four optical techniques at four locations from the base towards the fundus in the gastric conduit (Loc1, Loc2, Loc3, Loc4). The primary outcome included 14 quantitative parameters and the anastomotic leakage rate. Imaging was performed in 22 patients during oesophagectomy. Ten out of 14 quantitative parameters significantly indicated a reduced perfusion towards the fundus of the gastric conduit. Anastomotic leakage occurred in 4/22 patients (18.4%). At Loc4, the FA quantitative values for “T1/2” and “mean slope” differed between patients with and without anastomotic leakage (p = 0.025 and p = 0.041, respectively). A quantitative perfusion assessment during oesophagectomy is feasible using optical imaging techniques, of which FA is the most promising for future research.