Takashi Komiyama

An objective assessment of intermittent claudication by near-infrared spectroscopy

Changes in tissue oxygenation in the calf muscle were measured by near-infrared spectroscopy (NIRS) in 62 patients who complained of intermittent claudication in the calf during a treadmill test. Three distinctive patterns of oxygenated and deoxygenated haemoglobin were observed. None of the type 0 cases were severe (i.e., unable to walk for more than 5 minutes), while 37 and 82% of the type 1 and type 2 cases were severe, respectively. The mean maximum walking distance of type 1 was significantly longer than that of type 2 (179 +/- 70 m and 109 +/- 46 m, respectively; p < 0.005), while the mean ankle-brachial pressure index at rest of type 1 was not significantly different from that of type 2 (0.68 +/- 0.19 and 0.61 +/- 0.23, respectively). Our results indicate that NIRS can be used to accurately assess the severity of intermittent claudication.

Influence of popliteal vein thrombosis on subsequent ambulatory venous function measured by near-infrared spectroscopy☆

BACKGROUND To determine the influence of the site affected by thrombi on the subsequent venous physiology, we examined patients with postthrombotic syndrome (PTS) with respect to ambulatory venous function using near-infrared spectroscopy (NIRS). METHODS Fifty-one limbs of 45 patients, for whom more than 1 year had passed since an acute episode of deep vein thrombosis, were studied. Seventeen limbs were asymptomatic, 27 had mild symptoms (edema only), and 7 showed severe symptoms (skin changes). The mean duration of PTS was 8.2 years. All of the patients underwent a treadmill walking test with simultaneous NIRS. Deoxygenated hemoglobin was continuously measured during exercise. The ambulatory venous retention index (AVRI) obtained from the serial deoxygenated hemoglobin changes was calculated in each patient. The location of thrombi at the onset of deep vein thrombosis was identified by venography. RESULTS The calculated AVRI was apparently related to the clinical symptoms of PTS. The limbs initially involved with popliteal vein thrombosis showed significantly higher AVRI values than those without popliteal vein thrombosis. CONCLUSIONS The clinical severity of PTS is correlated well with the degree of venous retention during exercise. Initial involvement of the popliteal vein is an important factor determining subsequent venous hemodynamics in patients with PTS.

Differences in oxygen re-saturation of thigh and calf muscles after two treadmill stress tests.

Spatially resolved near-infrared oximeters quantify non-invasively muscle haemoglobin oxygen saturation (TOI) and, indirectly, local venous oxygen saturation (SvO(2)) and blood flow (MBF). TOI, SvO(2) and MBF of vastus lateralis and medial gastrocnemius were investigated after 5-min walking (3.2 km/h) and running (9.6 km/h) (n=7). The values of TOI were unchanged in the vastus lateralis during walking, whilst decreased during running in both muscles. For both muscles, TOI and SvO(2) values after walking were significantly greater than those found after running (P=0.043). The TOI went back (in 2 min) to its baseline value after walking in both muscles, whilst more slowly (in 4 min) after running in vastus lateralis. After running TOI of medial gastrocnemius had a tendency to be higher than the baseline value (reactive hyperaemia), concomitantly to the high MBF (twice the control value). The diverse oxygen demand in the stress tests and the consequent different pattern of TOI recovery reflect the different engagement of the two muscles. In conclusion, these results demonstrated the utility of TOI, independent of MBF and SvO(2), to be measured upon specific stress testing for differentiating the severity of peripheral vascular diseases and for assessing the collateral blood flow.

A new method for the assessment of venous insufficiency in primary varicose veins using near-infrared spectroscopy

PURPOSE Patients with chronic venous insufficiency (CVI) were evaluated from the aspect of ambulatory venous function using near-infrared spectroscopy (NIRS). METHODS Seventy-two primary varicose veins of 59 patients (varicose group) and 20 normal limbs of 13 volunteers (normal group) were studied. The affected limbs of the patients were divided into three groups according to the classification advocated by an International Consensus Committee in 1995: mild CVI with class 2 or 3 (50 limbs); moderate CVI with class 4 (11 limbs); and severe CVI with class 5 or 6 (11 limbs). All of the patients underwent a treadmill walking test, during which NIRS was applied. Oxygenated hemoglobin (OxyHb) and deoxygenated hemoglobin (DeoHb) were continuously measured by NIRS during exercise. The ambulatory venous retention index (AVRI) obtained from serial changes in DeoHb was assessed comparatively in the four groups (normal and mild to severe CVI). In addition, 19 limbs in 13 patients were evaluated with air plethysmography for comparison with the data obtained by NIRS. RESULTS Two distinct patterns of DeoHb change were observed. During exercise, the DeoHb level decreased in the normal group as a result of calf muscle contraction, whereas in the varicose group the DeoHb level rose because of an apparent venous reflux into the calf muscles. AVRI studies demonstrated a significant difference (p < 0.0001) among groups. Although there was no apparent relationship between AVRI and ejection fraction, AVRI showed a significant correlation with the venous filling index (r = 0.61) and a weak correlation with the residual volume fraction (r = 0.41). CONCLUSION NIRS is useful for accurately assessing ambulatory venous dysfunction in patients with primary varicose veins.