Anastomotic leakage is one of the most severe complications after esophageal resection with gastric tube reconstruction. Impaired perfusion of the gastric fundus is seen as the main contributing factor for this complication. Optical modalities show potential in recognizing compromised perfusion in real time, when ischemia is still reversible. This review provides an overview of optical techniques with the aim to evaluate the (1) quantitative measurement of change in perfusion in gastric tube reconstruction and (2) to test which parameters are the most predictive for anastomotic leakage. A Pubmed, MEDLINE, and Embase search was performed and articles on laser Doppler flowmetry (LDF), near-infrared spectroscopy (NIRS), laser speckle contrast imaging (LSCI), fluorescence imaging (FI), sidestream darkfield microscopy (SDF), and optical coherence tomography (OCT) regarding blood flow in gastric tube surgery were reviewed. Two independent reviewers critically appraised articles and extracted the data: Primary outcome was quantitative measure of perfusion change; secondary outcome was successful prediction of necrosis or anastomotic leakage by measured perfusion parameters. Thirty-three articles (including 973 patients and 73 animals) were selected for data extraction, quality assessment, and risk of bias (QUADAS-2). LDF, NIRS, LSCI, and FI were investigated in gastric tube surgery; all had a medium level of evidence. IDEAL stage ranges from 1 to 3. Most articles were found on LDF (n = 12), which is able to measure perfusion in arbitrary perfusion units with a significant lower amount in tissue with necrosis development and on FI (n = 12). With FI blood flow routes could be observed and flow was qualitative evaluated in rapid, slow, or low flow. NIRS uses mucosal oxygen saturation and hemoglobin concentration as perfusion parameters. With LSCI, a decrease of perfusion units is observed toward the gastric fundus intraoperatively. The perfusion units (LDF, LSCI), although arbitrary and not absolute values, and low flow or length of demarcation to the anastomosis (FI) both seem predictive values for necrosis intraoperatively. SDF and OCT are able to measure microvascular flow, intraoperative prediction of necrosis is not yet described. Optical techniques aim to improve perfusion monitoring by real-time, high-resolution, and high-contrast measurements and could therefore be valuable in intraoperative perfusion mapping. LDF and LSCI use perfusion units, and are therefore subjective in interpretation. FI visualizes influx directly, but needs a quantitative parameter for interpretation during surgery.

In this study; an OCT-based intra-operative imaging method for blood flow detection during esophagectomy with gastric tube reconstruction is investigated. Change in perfusion of the gastric tube tissue can lead to ischemia; with a high morbidity and mortality as a result. Anastomotic leakage (incidence 5–20%) is one of the most severe complications after esophagectomy with gastric tube reconstruction. Optical imaging techniques provide for minimal-invasive and real-time visualization tools that can be used in intraoperative settings. By implementing an optical technique for blood flow detection during surgery; perfusion can be imaged and quantified and; if needed; perfusion can be improved by either a surgical intervention or the administration of medication. The feasibility of imaging gastric microcirculation in vivo using optical coherence tomography (OCT) during surgery of patients with esophageal cancer by visualizing blood flow based on the speckle contrast from M-mode OCT images is studied. The percentage of pixels exhibiting a speckle contrast value indicative of flow was quantified to serve as an objective parameter to assess blood flow at 4 locations on the reconstructed gastric tube. Here; it was shown that OCT can be used for direct blood flow imaging during surgery and may therefore aid in improving surgical outcomes for patients.

Compromised perfusion as a result of surgical intervention causes a reduction of oxygen and nutrients in tissue and therefore decreased tissue vitality. Quantitative imaging of tissue perfusion during reconstructive surgery, therefore, may reduce the incidence of complications. Non-invasive optical techniques allow real-time tissue imaging, with high resolution and high contrast. The objectives of this study are, first, to assess the feasibility and accuracy of optical coherence tomography (OCT), sidestream darkfield microscopy (SDF), laser speckle contrast imaging (LSCI), and fluorescence imaging (FI) for quantitative perfusion imaging and, second, to identify/search for criteria that enable risk prediction of necrosis during gastric tube and free flap reconstruction. This prospective, multicenter, observational in vivo pilot study will assess tissue perfusion using four optical technologies: OCT, SDF, LSCI, and FI in 40 patients: 20 patients who will undergo gastric tube reconstruction after esophagectomy and 20 patients who will undergo free flap surgery. Intra-operative images of gastric perfusion will be obtained directly after reconstruction at four perfusion areas. Feasibility of perfusion imaging will be analyzed per technique. Quantitative parameters directly related to perfusion will be scored per perfusion area, and differences between biologically good versus reduced perfusion will be tested statistically. Patient outcome will be correlated to images and perfusion parameters. Differences in perfusion parameters before and after a bolus of ephedrine will be tested for significance. This study will identify quantitative perfusion-related parameters for an objective assessment of tissue perfusion during surgery. This will likely allow early risk stratification of necrosis development, which will aid in achieving a reduction of complications in gastric tube reconstruction and free flap transplantation. Clinicaltrials.gov registration number NCT02902549 . Dutch Central Committee on Research Involving Human Subjects registration number NL52377.018.15.

Compromised perfusion due to ligation of arteries and veins in esophagectomy with gastric tube reconstruction often (5–20%) results in necrosis and anastomotic leakage, which relate to high morbidity and mortality (3–4%). Ephedrine is used widely in anesthesia to treat intraoperative hypotension and may improve perfusion by the increase of cardiac output and mean arterial pressure (MAP). This study tests the effect of ephedrine on perfusion of the future anastomotic site of the gastric conduit, measured by laser speckle contrast imaging (LSCI). This prospective, observational, in vivo pilot study includes 26 patients undergoing esophagectomy with gastric tube reconstruction from October 2015 to June 2016 in the Academic Medical Center (Amsterdam). Perfusion of the gastric conduit was measured with LSCI directly after reconstruction and after an increase of MAP by ephedrine 5 mg. Perfusion was quantified in flux (laser speckle perfusion units, LSPU) in four perfusion locations, from good perfusion (base of the gastric tube) toward decreased perfusion (fundus). Intrapatient differences before and after ephedrine in terms flux were statistically tested for significance with a paired t-test. LSCI was feasible to image gastric microcirculation in all patients. Flux (LSPU) was significantly higher in the base of the gastric tube (791 ± 442) compared to the fundus (328 ± 187) (P < 0.001). After administration of ephedrine, flux increased significantly in the fundus (P < 0.05) measured intrapatients. Three patients developed anastomotic leakage. In these patients, the difference between measured flux in the fundus compared to the base of the gastric tube was high. This study presents the effect of ephedrine on perfusion of the gastric tissue measured with LSCI in terms of flux (LSPU) after esophagectomy with gastric tube reconstruction. We show a small but significant difference between flux measured before and after administration of ephedrine in the future anastomotic tissue (313 ± 178 vs. 397 ± 290). We also show a significant decrease of flux toward the fundus.