Assessment of the Severity of Ischaemia and the Outcomes of Revascularisation in Peripheral Arterial Disease Patients Based on the Skin Microcirculatory Response to a Thermal Load Test.

OBJECTIVE: This study investigated the skin microcirculatory response to a thermal load test using a laser Doppler flowmetry device to evaluate the severity of limb ischaemia and the outcomes of revascularisation in patients with peripheral arterial disease (PAD). METHODS: A total of 34 PAD patients (39 limbs) including 17 critical limb ischaemia (CLI) patients (21 limbs) who underwent revascularisation were enrolled. The skin microcirculation of the dorsal side of the affected foot was investigated for 15 minutes after local heating. The tests were performed both before and after revascularisation, and several parameters gleaned from the microcirculatory fluctuations were analysed and compared with the ankle brachial pressure index and the transcutaneous oxygen tension (tcPO2) values. RESULTS: Among the parameters, significant differences were observed between the CLI patients and patients with claudication with regard to the increasing phase time (Tinc), the difference in the perfusion values at the onset and the peak of the transient increase in blood perfusion (PΔ), the slope of the transient increase in blood perfusion (Sin), and the slope of the decrease in blood perfusion after the peak (Sde). In CLI patients, the PΔ, Sin, and Sde values increased significantly after revascularisation. In the patients with claudication, the changes in the parameters after revascularisation were not statistically significant. The Sde showed the most statistically significant correlation with the tcPO2 value (ρ .759, p < .001). CONCLUSIONS: Thermal load testing can be used to evaluate the severity of limb ischaemia in patients with PAD.

Simultaneous assessment of blood coagulation and hematocrit levels in dielectric blood coagulometry.

BACKGROUND: In a whole blood coagulation test, the concentration of any in vitro diagnostic agent in plasma is dependent on the hematocrit level but its impact on the test result is unknown. OBJECTIVE: The aim of this work was to clarify the effects of reagent concentration, particularly Ca2+, and to find a method for hematocrit estimation compatible with the coagulation test. METHODS: Whole blood coagulation tests by dielectric blood coagulometry (DBCM) and rotational thromboelastometry were performed with various concentrations of Ca2+ or on samples with different hematocrit levels. DBCM data from a previous clinical study of patients who underwent total knee arthroplasty were re-analyzed. RESULTS: Clear Ca2+ concentration and hematocrit level dependences of the characteristic times of blood coagulation were observed. Rouleau formation made hematocrit estimation difficult in DBCM, but use of permittivity at around 3 MHz made it possible. The re-analyzed clinical data showed a good correlation between permittivity at 3 MHz and hematocrit level (R2=0.83). CONCLUSIONS: Changes in the hematocrit level may affect whole blood coagulation tests. DBCM has the potential to overcome this effect with some automated correction using results from simultaneous evaluations of the hematocrit level and blood coagulability.

Significance of the Lateral Thoracic Artery in Pectoralis Major Musculocutaneous Flap Reconstruction: Quantitative Assessment of Blood Circulation Using Indocyanine Green Angiography.

Free tissue transfer is the preferred reconstruction option in most major head and neck reconstructions. The pectoralis major muscle musculocutaneous (PMMC) flap is commonly used in salvage of necrotic free flaps and is the first choice for patients who are not candidates for free flaps. The lateral thoracic artery (LTA), which is thought to contribute to blood perfusion of the inferior and lateral mammary area, is not preserved in a conventionally harvested PMMC flap. With regard to blood supply, it has been suggested that the LTA should be preserved, in addition to the pectoral branch of the thoracoacromial artery, when a skin island is designed in the lower chest to attain a pedicle length sufficient for head and neck reconstruction. However, an effect on hemodynamic improvement using the LTA has not been shown quantitatively. In this study, we examined 8 patients with oral cancer who underwent reconstruction procedures with a bipedicle PMMC flap that included the LTA, in addition to the thoracoacromial artery. Intraoperative indocyanine green angiography was performed to examine circulation to the PMMC flap with or without LTA clamping after harvesting. After image processing, data were analyzed using a new quantitative perfusion assessment system with parameters that we recently established for assessment of peripheral arterial disease of the lower limbs. All patients had good clinical courses with whole-flap survival, no vascular insufficiency of the skin island, and no fistula formation. Intraoperative indocyanine green angiography showed an increased inflow rate into the skin island in an LTA-declamped condition in all cases, implying that the preserved LTA increased the blood supply to skin islands in the pectoralis major muscle. We conclude that preserving the LTA in a PMMC flap can increase blood perfusion and stabilize the vascularity of the flap, making the reconstruction more effective and reliable than with use of a conventionally harvested flap. Therefore, it is worthwhile to preserve the LTA as a major contributor to a lateral and distal PMMC flap.

Novel assessment tool based on laser speckle contrast imaging to diagnose severe ischemia in the lower limb for patients with peripheral arterial disease.

OBJECTIVE: We propose a new assessment tool to diagnose severe ischemia of the lower limb in peripheral arterial disease, using laser speckle contrast imaging to evaluate heating-induced microcirculatory fluctuations in the proximal and distal sites of the dorsal foot. STUDY DESIGN: A cross-sectional study. METHODS: We recorded the slope describing the behavior of perfusion values (decrease or plateau) following the initial, heating-induced increase in perfusion in 63 feet of patients with clinical signs of peripheral arterial disease. RESULTS: The plateau and decrease groups were defined as having perfusion slopes of <0.20 and ≥0.20 PU/min, respectively. Transcutaneous oxygen tension was significantly lower (P < 0.001) in the plateau than in the decrease group (8 vs. 45 mmHg), indicating more severe ischemia. The laser speckle contrast imaging thermal load test discriminated transcutaneous oxygen tension <30 mmHg with good sensitivity (78.7%) and specificity (96.2%), and an area under the curve of 0.908. CONCLUSIONS: Both transcutaneous oxygen tension and the laser speckle contrast imaging thermal load test are useful in diagnosing severe ischemia in the foot. Lasers Surg. Med. 49:645-651, 2017. © 2017. The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Assessment of vascular autonomic function using peripheral arterial tonometry.

Peripheral autonomic function is impaired in diabetic polyneuropathy. However, it is difficult to evaluate it due to the lack of non-invasive quantitative assessment. We aimed to establish a novel index to evaluate vascular autonomic function using reactive hyperemia peripheral arterial tonometry (RH-PAT), a widely performed endothelial function test. Sixty-five subjects were enrolled, including healthy subjects, cases with sympathetic nerve blockers, and diabetic patients. RH-PAT was performed with 5-min blood flow occlusion in unilateral arm. We calculated the reduction ratio of the post-occlusion pulse amplitude to the baseline in the non-occluded arm (RPN), with 1-min sliding window. In healthy subjects, RPN gradually increased with time-dependent manner. However, this phenomenon was eliminated in cases with sympathetic nerve blockers. Plasma concentration of norepinephrine was measured before and after the blood flow occlusion, which showed a significant increase. We then compared RPNs with the change in heart rate variability (HRV) parameters. RPN calculated at 5 min after the reperfusion had the highest correlation with the change in sympathetic HRV parameter, and thus, we named sympathetic hypoemia index (SHI). Finally, we studied the relationship between SHI and diabetes. SHI was significantly lower in diabetic patients than matched controls. SHI, a novel index derived from RH-PAT, represented the peripheral sympathetic activity. SHI may be useful for assessing the vascular autonomic activity in diabetic patients.