Intraoperative quality assessment of tissue perfusion with indocyanine green (ICG) in a porcine model of mesenteric ischemia

Utility of indocyanine green fluorescent dye in emergency general surgery: a review of the contemporary literature

For decades, indocyanine green (ICG) has been available for medical and surgical use. The indications for ICG use in surgery have expanded where guided surgery directed by fluorescence and near-infrared fluorescent imaging offers numerous advantages. Recently, surgeons have reported using ICG operative navigation in the emergency setting, with fluorescent cholangiography being the most common procedure. The utility of ICG also involves real-time perfusion assessment, such as ischemic organs and limbs. The rising use of ICG in surgery can be explained by the ICG's rapid technological evolution, accuracy, ease of use, and great potential to guide precision surgical diagnosis and management. The review aims to summarize the current literature on the uses of ICG in emergency general surgery. It provides a comprehensive and practical summary of the use of ICG, including indication, route of administration, and dosages. To simplify the application of ICG, we subdivided its use into anatomical mapping and perfusion assessment. Anatomical mapping includes the biliary tree, ureters, and bowel. Perfusion assessment includes bowel, pancreas, skin and soft tissue, and gonads. This review provides a reference to emergency general surgeons to aid in implementing ICG in the emergency setting for more enhanced and safer patient care.

Mesenteric Vein Thrombosis following Sleeve Gastrectomy: A Case Report and Review of the Literature

INTRODUCTION

Acute mesenteric ischemia (AMI) is a rare but lethal disease. Mesenteric vein thrombosis (VAMI) is a subtype of AMI. Morbid obesity is usually accompanied by hypertension, hyperlipidemia, or diabetes mellitus, which are risk factors associated with AMI.

CASE PRESENTATION

We present a 28-year-old man with VAMI post-laparoscopic sleeve gastrectomy. He was first misdiagnosed with intestinal obstruction. Superior VAMI was confirmed after computed tomography angiography. Laparotomy, resection of the necrotic small bowel, and ostomy were performed immediately.

CONCLUSION

Patients with morbid obesity accompanied by hypertension, hyperlipidemia, or diabetes mellitus have a high risk of AMI. Abdominal pain with sudden onset should be considered AMI. Anticoagulation therapy post-sleeve gastrectomy might help reduce the incidence of AMI.

ICG-augmented hyperspectral imaging for visualization of intestinal perfusion compared to conventional ICG fluorescence imaging: an experimental study

BACKGROUND

Small bowel malperfusion (SBM) can cause high morbidity and severe surgical consequences. However, there is no standardized objective measuring tool for the quantification of SBM. Indocyanine green (ICG) imaging can be used for visualization, but lacks standardization and objectivity. Hyperspectral imaging (HSI) as a newly emerging technology in medicine might present advantages over conventional ICG fluorescence or in combination with it.

METHODS

HSI baseline data from physiological small bowel, avascular small bowel and small bowel after intravenous application of ICG was recorded in a total number of 54 in-vivo pig models. Visualizations of avascular small bowel after mesotomy were compared between HSI only (1), ICG-augmented HSI (IA-HSI) (2), clinical evaluation through the eyes of the surgeon (3) and conventional ICG imaging (4). The primary research focus was the localization of resection borders as suggested by each of the four methods. Distances between these borders were measured and histological samples were obtained from the regions in between in order to quantify necrotic changes 6 h after mesotomy for every region.

RESULTS

StO2 images (1) were capable of visualizing areas of physiological perfusion and areas of clearly impaired perfusion. However, exact borders where physiological perfusion started to decrease could not be clearly identified. Instead, IA-HSI (2) suggested a sharp-resection line where StO2 values started to decrease. Clinical evaluation (3) suggested a resection line 23 mm (±7 mm) and conventional ICG imaging (4) even suggested a resection line 53 mm (±13 mm) closer towards the malperfused region. Histopathological evaluation of the region that was sufficiently perfused only according to conventional ICG (R3) already revealed a significant increase in pre-necrotic changes in 27% (±9%) of surface area. Therefore, conventional ICG seems less sensitive than IA-HSI with regards to detection of insufficient tissue perfusion.

CONCLUSIONS

In this experimental animal study, IA-HSI (2) was superior for the visualization of segmental SBM compared to conventional HSI imaging (1), clinical evaluation (3) or conventional ICG imaging (4) regarding histopathological safety. ICG application caused visual artifacts in the StO2 values of the HSI camera as values significantly increase. This is caused by optical properties of systemic ICG and does not resemble a true increase in oxygenation levels. However, this empirical finding can be used to visualize segmental SBM utilizing ICG as contrast agent in an approach for IA-HSI. Clinical applicability and relevance will have to be explored in clinical trials.

LEVEL OF EVIDENCE

Not applicable. Translational animal science. Original article.

Fluorescent Imaging in Visceral Surgery: Current Opportunities and Future Perspectives

Background

Fluorescent imaging using indocyanine green (FI-ICG) has become quite popular in the past century, giving the surgeon various pre- and intraoperative approaches in visceral surgery. Nevertheless, several aspects and pitfalls of using the technology need to be addressed.

Summary

This article focused on the applications of FI-ICG in esophageal and colorectal surgery as this is where the clinical relevance is most important. Important benchmark studies were summarized to explain the background. In addition, dosage, the timing of application, and future perspectives - especially quantification methods - were the article's content.

Key Message

There are currently encouraging data on the use of FI-ICG, particularly concerning perfusion assessment to reduce anastomotic leakage, although its use is mainly subjective. The optimal dosage remains unclear; for perfusion evaluation, it should be around 0.1 mg/kg body weight. Moreover, the quantification of FI-ICG opens new possibilities, so that reference values may be available in the future. However, in addition to perfusion measurement, the detection of additional hepatic lesions such as liver metastases or lesions of peritoneal carcinomatosis is also possible. A standardization of FI-ICG and further studies are needed to fully utilize FI-ICG.