Utility of a Finger-Mounted Tissue Oximeter with Near-Infrared Spectroscopy to Evaluate Limb Ischemia in Patients with Peripheral Arterial Disease

Evaluation of the blood flow in reconstructed gastric tube and its relation to anastomosis leakage

OBJECTIVES

Anastomotic leakage in esophageal cancer surgery may be reduced by evaluating the blood flow to the reconstructed organ, but quantitative evaluation of arterial and venous blood flow is difficult. This study aimed to quantitatively assess blood flow using a new technique, as well as determine the relationship between the blood flow in the gastric tube and anastomotic leakage using near-infrared spectroscopy.

METHODS

This single-center, observational study included 50 patients aged 51-82 years who underwent radical esophagectomy with gastric tube reconstruction for esophageal cancer between June 2022 and January 2023. Regional tissue oxygen saturation was measured at the antrum (point X), the anastomotic point (point Z), and the midpoint between points X and Z (point Y) before and after gastric tube formation. These three points of oxygen saturation were investigated in relation to anastomotic leakage.

RESULTS

When comparing the presence of leakage to its absence, regional tissue oxygen saturation at points X and Z after gastric tube formation was significantly lower (X: p = 0.03, Z: p = 0.02), with the decreasing rate significantly higher at point Z (p = 0.01). There was no significant difference in the decreasing rate of regional tissue oxygen saturation between points X and Y (X: p = 0.052, Y: p = 0.83).

CONCLUSION

Regional tissue oxygen saturation levels may be useful for measuring blood flow and could be a predictor of anastomotic leakage.

Utility of Superb Microvascular Imaging in the Assessment of Foot Perfusion in Patients with Critical Limb Ischemia

(1) Background: Although the ankle-brachial index (ABI) and skin perfusion pressure (SPP) are commonly used to evaluate the peripheral circulation in critical limb ischemia (CLI), they often cannot be performed on sore areas. We investigated the utility of superb microvascular imaging (SMI) for assessing foot perfusion in CLI patients. (2) Methods: We measured the SMI-based vascular index (SMI-VI) at six sites in the foot before and after endovascular treatment (EVT) in 50 patients with CLI who underwent EVT of the superficial femoral artery and compared the results with SPP values and the ABI. (3) Results: SMI visualized foot perfusion in all subjects in accordance with the angiosome, including the toe areas, while the ABI was unmeasurable in three patients on hemodialysis and SPP failed in four patients. SMI-VI values were significantly lower in the CLI group than in controls, and the plantar SMI-VI had the highest diagnostic performance for CLI (sensitivity 88.6%, specificity 95.6%). After EVT, the increase in the SMI-VI was positively correlated with the increase in SPP but not that in the ABI, implying that the SMI-VI reflects foot microcirculation. (4) Conclusions: SMI enables the visualization and quantification of foot microcirculation based on the angiosome. SMI has high utility as a tool for assessing foot perfusion in CLI.

Real-time assessment of tissue oxygen saturation during endovascular therapy for chronic limb threatening ischemia using a novel oximeter

In the present study, we have introduced a novel real-time, near-infrared spectroscopy oximeter, the TOE-20 (Astem, Co, Ltd, Kawasaki, Japan), which can simultaneously measure the regional tissue oxygen saturation (rSO₂) in the skin and subcutaneous tissue at three angiosomes of the foot. Seven patients with chronic limb threatening ischemia who had undergone successful revascularization of the superficial femoral artery were included. The analysis revealed a significant correlation between the rSO₂ and skin perfusion pressure. After revascularization, the rSO₂ and skin perfusion pressure had both increased at the three regions, although the increase at the plantar foot was insignificant. These results indicate that the TOE-20 can be successfully used to monitor the rSO₂ during endovascular treatment.

The Patency of Tibial/Peroneal Arteries Affects the Increment of Regional Tissue Saturation of Oxygen in Each Angiosome after Superficial Femoral Artery Revascularization

Objective: The angiosome model is a controversial concept in the revascularization of patients with chronic limb-threatening ischemia (CLTI). The aim of this study was to demonstrate the importance of patency of the tibial/peroneal arteries for regional tissue oxygenation in each angiosome during endovascular therapy (EVT) of the superficial femoral artery (SFA).

Materials and Methods: We devised a novel near-infrared spectroscopy oximeter, “TOE-20,” for real-time monitoring of regional tissue oxygen saturation (rSO₂). Using TOE-20, we prospectively assessed rSO₂ at each angiosome in 23 CLTI patients who underwent successful revascularization of the SFA. During EVT, three sensor probes were placed at the dorsal foot, plantar foot, and outer ankle for rSO₂ monitoring.

Results: At the end of EVT, rSO₂ at all angiosomes was significantly elevated by SFA revascularization. The change in rSO₂ in each angiosome was larger in patients with patent relevant arteries than in those with occluded relevant arteries (i.e., anterior tibial artery patency, posterior tibial artery patency, and peroneal artery patency).

Conclusion: The patency of the tibial/peroneal arteries is important for regional tissue oxygenation in EVT. Using TOE-20 and rSO₂-based revascularization, it may possible to anticipate whether an ischemic ulcer will heal or not.

Tissue Oxygen Saturation during Gastric Tube Reconstruction with Cervical Anastomosis for Esophagectomy: A Case Series

BACKGROUND

One cause of anastomotic leakage after radical esophagectomy is blood flow insufficiency at the cervical anastomosis site. .

METHODS

Eighteen patients, who underwent radical esophagectomy with gastric tube reconstruction, were studied. The regional tissue oxygen saturation (rSO2) was measured at the tip (point pre 0) and 2, 4, and 6 cm on the distal side of the tip (point pre 1, pre 2, and pre 3, respectively) before the gastric tube was raised to the cervical site through the retrosternal route. After that, rSO2 was measured at the tip, 2 and 4 cm on the distal side of the tip (points post 0, post 1, and post 2), the actual anastomotic site (point AN), and the chest skin as an indicator of whole-body oxygenation. The relationship between rSO2 scores and the rate of anastomotic leakage was determined.

RESULTS

The mean rSO2 at pre 0, pre 1, pre 2, and pre 3 were 48.9%, 52.3%, 54.8%, and 56.9%, respectively (p < 0.05). The mean rSO2 at post 0, post 1, and post 2 were 47.8%, 50.5%, and 52.3%, respectively, and the rSO2 at point AN was 52.1%.Anastomotic leakage was found in 6 patients. The rSO2 at points pre 0, pre 1, and pre 2, post 0 and point AN were significantly lower in patients with anastomosis leakage than those without (p < 0.05).

CONCLUSION

Tissue oxygen saturation monitoring was a useful indicator of blood flow insufficiency in the gastric tube during radical esophagectomy.

Tissue Oximeter with Selectable Measurement Depth Using Spatially Resolved Near-Infrared Spectroscopy

Tissue oxygenation sensing at a few millimeters deep is useful for surgical and postoperative management. However, the measurement sensitivity at each depth and the proper sensor combination have not been clarified. Here, the measurement characteristics of oximetry by spatially resolved near-infrared spectroscopy were analyzed using Monte Carlo simulation and phantom experiment. From summing the sensitivities of each depth, it was quantitatively found that the measurement sensitivity curve had a peak, and the measurement depth can be adjusted by combining the two distances between the light source and the detector. Furthermore, the gastric tissue was 10–20% smaller in terms of measurement depth than the skin-subcutaneous tissue. A miniaturized oximeter was prototyped so that it could be used in combination with an endoscope or laparoscope. The optical probes consisted of light emitting diodes with wavelengths of 770 nm and 830 nm and photodetectors located 3 to 30 mm from the light source. Phantom experiments using the probes demonstrated the tendency of theoretical analysis. These results suggest the possibility of measuring tissue oxygen saturation with a selectable measurement depth. This selectable method will be useful for obtaining oxygenation information at a depth of 2–5 mm, which is difficult to measure using only laparoscopic surface imaging.

The use of near-infrared spectroscopy in the diagnosis of peripheral artery disease: A systematic review

BACKGROUND

Peripheral arterial disease is a stenosis or occlusion of peripheral arteries that results in compromised blood flow and muscle ischemia. The available diagnostic methods are mostly used to measure and visualize blood flow and are not useful in the evaluation of perfusion, especially in diabetic patients, which is now considered to be a research priority by most of the vascular societies around the world as this is still a relatively poorly studied phenomenon.

OBJECTIVE

The aim of this review is to explore the clinical significance of muscle tissue oxygenation monitoring in lower-extremity peripheral artery disease diagnosis using the near-infrared spectroscopy method.

METHODS

A systematic search in PubMed, CINAHL, and Cochrane databases was performed to identify clinical near-infrared spectroscopy (NIRS) studies in English and Russian, published until September 2019, involving muscle tissue oxygenation in peripheral arterial disease (PAD). The manuscripts were reviewed by two researchers independently and scored on the quality of the research using MINORS criteria.

RESULTS

After screening 443 manuscripts, 23 studies (n = 1580) were included. NIRS-evaluated recovery time seems to be more accurate than ankle-brachial index in diabetic patients to differentiate between moderate and severe claudication. Consistent findings across all the included studies showed that both the oxygenation and deoxygenation rates as well as the recovery times varied from patient to patient and therefore were not suitable for standardization.

CONCLUSIONS

The clinical relevance of routine use of NIRS to diagnose PAD is unproven; therefore, its use is not currently part of standard-of-care for patients with PAD since the absolute values seem to vary significantly, depending on the outside conditions. More data need to be provided on the possible use of NIRS monitoring intraoperatively where the conditions can be more controlled.

Usefulness of a finger-mounted tissue oximeter with near-infrared spectroscopy for evaluating the intestinal oxygenation and viability in rats

PURPOSE

To investigate the utility of the device for evaluating intestinal oxygenation and viability using an animal model.

METHODS

Sprague-Dawley rats underwent laparotomy under general anesthesia, and the blood vessels in the terminal ileum were clamped to create ischemia. We measured the regional tissue oxygenation saturation (rSO2) using an oximeter after 1, 3, and 6 h of vessel clamping. Ischemic tissue damage was assessed using a histological score. The intestine was reperfused after each clamping period, and intestinal rSO2 and survival rate were evaluated.

RESULTS

When reperfusion was performed at 1 and 3 h after ischemia, rSO2 increased after 10 min, and it improved to the same level as for normal intestine after 1 h; all rats survived for 1 week. In contrast, after 6 h of ischemia, rSO2 did not increase after reperfusion, and all animals died within 2 days. The histological scores increased after 1 h of reperfusion, with longer clamping periods.

CONCLUSION

A finger-mounted tissue oximeter could evaluate intestinal ischemia and the viability, which is thus considered to be a promising result for future clinical application.

A Pilot Study Investigating the Use of Regional Oxygen Saturation as a Predictor of Ischemic Wound Healing Outcome after Endovascular Treatment in Patients with Chronic Limb-Threatening Ischemia

Objective: To determine the prognostic value of regional tissue oxygenation saturation (rSO₂) for ulcer healing after endovascular treatment (EVT) of peripheral arterial disease (PAD).

Materials and Methods: Among PAD patients, 34 patients with chronic limb-threatening ischemia underwent EVT for limb salvage. We retrospectively analyzed the cutoff rSO₂ values on postoperative day 1 to predict ulcer healing and patient prognosis. Skin perfusion pressure (SPP) and transcutaneous oxygen pressure (TcPO₂) were also used to assess wound healing.

Results: A finger-mounted tissue oximeter can easily measure rSO₂ on the dorsal foot. Among the 34 patients, the ulcer healed in 25, and no changes were observed in 2 patients at 1 month after EVT. However, 7 patients needed major amputation at the same time. Wound healing was achieved in all patients with rSO₂≥50%. With this cutoff, the sensitivity and specificity of the new device for wound healing were 100% and 64%, respectively. In all the wound healing cases, SPP was ≥45 mmHg, and TcPO₂ was ≥40 mmHg.

Conclusion: To assess limb ischemia, rSO₂ can be measured quickly and easily using this device. We suggest that an rSO₂>50% shows good prognosis for ulcer healing.

Term Newborns with relatively low Tissue Oxygen Saturation Levels soon after Birth are predisposed to Neonatal Respiratory Disorders in Low-risk, Elective Cesarean Sections

Background: Neonatal respiratory disorders, such as transient tachypnea of the newborn and respiratory distress syndrome, occur frequently after an elective cesarean delivery. Although conventional pulse oximetry is recommended for neonatal resuscitation, it often requires several minutes after birth to obtain a reliable signal. In a previous study, we used novel tissue oximetry equipment to detect fetal and neonatal early tissue oxygen saturation (StO₂) before and immediately after vaginal delivery. Therefore, we hypothesized that low neonatal StO₂ levels measured by tissue oximetry may lead to neonatal respiratory disorder after a scheduled cesarean delivery. Hence, this study aimed to evaluate the StO₂ levels measured by tissue oximetry in neonates with or without a respiratory disorder subsequently diagnosed after an elective cesarean delivery. Materials and methods: We enrolled 78 pregnant Japanese women who underwent an elective cesarean section at ≥36 weeks' gestation. After combined spinal and epidural anesthesia were administered to the mother, fetal StO₂ levels were measured by tissue oximetry using an examiner's finger-mounted sensor during a pelvic examination immediately before the cesarean section. We measured the neonatal StO₂ levels at 1, 3, and 5 minutes after birth and retrospectively compared the fetal and neonatal StO₂ levels with the incidence of subsequent diagnoses of neonatal respiratory disorders. Results: The data of StO₂ levels in 35 neonates were collected. Seven neonates (respiratory disorder (RD) group) were subsequently diagnosed with respiratory disorders by neonatal medicine specialists, whereas the 28 remaining neonates (NR group) were not. The median fetal StO₂ (interquartile range) of the RD and NR groups was 52.0% (41.8%-60.8%) and 42.5% (39.0%-52.5%), respectively (P = 0.12). The median neonatal StO₂ (interquartile range) of the RD and NR groups at 1 minute after birth was 42.0% (39.0%-44.0%) and 46.0% (42.0%-49.0%), respectively (P = 0.091). At 3 minutes after birth, the median neonatal StO₂ (interquartile range) of the RD and NR groups was 41.0% (39.0%-46.0%) and 47.0% (44.3%-53.5%), respectively (P = 0.004). Finally, at 5 minutes after birth, the median neonatal StO₂ (interquartile range) of the RD and NR groups was 45.0% (44.0%-52.0%) and 54.0% (49.3%-57.0%), respectively (P = 0.007). Conclusions: The StO₂ values in the RD group were lower than those in the NR group at 3 and 5 minutes after birth, suggesting that neonates with low StO₂ levels soon after birth may be predisposed to clinically diagnosed neonatal respiratory disorders.

Perioperative patient-controlled regional analgesia versus patient-controlled intravenous analgesia for patients with critical limb ischaemia: a study protocol for a randomised controlled trial

INTRODUCTION

Both regional analgesia and intravenous analgesia are frequently used perioperatively for patients with critical limb ischaemia (CLI). Nevertheless, the comparison of perioperative effect of regional and intravenous analgesia has not yet been thoroughly illustrated. This study will comprehensively compare patient-controlled regional analgesia (PCRA) and patient-controlled intravenous analgesia (PCIA) as two different perioperative analgesia approaches for patients with CLI. It investigates their effects on analgesia, reperfusion and the quality of recovery perioperatively, also aims to provide clinical evidence to those non-surgical patients with non-reconstructable arteries.

METHODS AND ANALYSIS

This trial is a randomised, single-centre, open-label, parallel trial with target sample size of 52 in total. Eligible participants will be randomly allocated to the PCRA group (group R) or the PCIA group (group I) after admission. Participants in group R will receive ultrasound-guided subgluteal sciatic catheterisation, followed by continuous PCRA infusion (0.2% ropivacaine 15 mL as loading dose, 8 mL/hour as background with a patient-controlled bolus of 6 mL). Participants in group I will receive PCIA (morphine is given in boluses of 1 mg as needed, background infusion at 1 mg/hour). Data will be collected at baseline (T0), 2 hours before revascularisation treatment (T1) and 2 hours before discharge (T2). The primary outcomes include the Numerical Rating Scale pain score at T1 and T2. The secondary outcomes include the perioperative transcutaneous oxygen pressure, the Tissue Haemoglobin Index, Hospital Anxiety and Depression Scale at T1 and T2; the Patient Global Impression of Change and patient satisfaction at T1 and T2; the perioperative cumulative morphine consumption, the length of postoperative hospital stay and adverse events.

ETHICS AND DISSEMINATION

This study received authorisation from the Institutional Review Board of Peking Union Medical College Hospital on 21 March 2017 (approval no. ZS-1289X). Study findings will be disseminated through presentations at scientific conferences or publications in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Registry (ChiCTR2000029298).

PROTOCOL VERSION

V.4CP.B2 (15 June 2020).

Target region oxygenation-based endovascular treatment in a chronic limb-threatening ischemia patient with multifocal arterial diseases

Patients with chronic limb-threatening ischemia often have multiple segmental diseases requiring revascularization. However, there is no defined milestone to indicate sufficient endovascular treatment (EVT). Using multiple near-infrared spectroscopic oximeters, we intraoperatively monitored regional tissue oxygen saturation (rSO2) to perform target region oxygenation-based EVT for a patient with chronic limb-threatening ischemia. Stent placement at the superficial femoral artery and angioplasty of the tibioperoneal trunk enabled rSO2 in the target ischemic regions (dorsal foot and heel) to be >50% for ulcer healing. We herein describe target region oxygenation-based EVT with rSO2 monitoring as an effective strategy for performing the minimum requisite procedures.