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Near-infrared spectroscopy (study of the spectra of wavelengths between 700 and 1,300 nanometers) can be used to calculate changes in the concentrations of oxygenated and deoxygenated blood. This is a noninvasive technique that may be used to evaluate metabolic improvement in tissue oxygenation. This technique has been used mainly in the study of the circulation of the brain. Research on animals has indicated that the oxygen consumption of muscles is in proportion to blood flow. A study was undertaken to determine if muscle oxygen consumption is reduced in patients with ischemic symptoms (due to reduced blood flow) of peripheral vascular disease, disease of the blood vessels in the limbs. Near-infrared spectroscopy was performed on calf muscles of 17 patients with peripheral vascular disease and 21 normal control subjects. Average oxygen consumption was significantly lower in the patient group than in the normal subjects. After ischemia was created by the use of a tourniquet, the return to maximum oxygenated hemoglobin level required an average of 40 seconds in patients, compared with an average of 20 seconds for controls. These results indicate that patients with peripheral vascular disease have reduced oxygen consumption by the calf muscles. (Consumer Summary produced by Reliance Medical Information, Inc.)

In some diseases and conditions, the blood circulation through the legs is diminished by blocked arteries, a condition known as arterial occlusive disease. A decreased blood supply to the legs can cause pain while walking or at rest. Blood circulation in the legs can be assessed by using the noninvasive technique of measuring the transcutaneous oxygen tension (TcPO2). TcPO2 is useful in determining a prognosis after diseased blood vessels in the legs have been surgically replaced or reopened. The influence of age, sex, smoking and diabetes on the TcPO2 was assessed in the legs in 129 patients. Blood pressure in the legs and clinical signs and symptoms of occlusive disease such as painful walking were also used to assess blood flow in the legs. Age, sex and smoking did not effect TcPO2 or the severity of the disease. Patients with diabetes had lower TcPO2, even when patients with similarly severe occlusive disease were compared. TcPO2 is a useful tool for assessing blood vessel blockage in diabetics. (Consumer Summary produced by Reliance Medical Information, Inc.)

The femoral artery and vein are the main vessels of the thigh and leg. These structures run through the thigh in a muscular compartment which is known as the adductor canal or the Hunter canal. The vessels leave the front of the thigh to enter the small popliteal cavity (the concavity at the back of the knee joint) by passing through a muscular hole called the adductor canal hiatus. This is a site where many problems of the vascular system occur. Seventy percent of all patients who have inadequate blood supply to their legs (suffering from intermittent claudication) have a reduction of the bore of vessels in this area. While 'local factors' have been hypothesized, an exact pathophysiologic mechanism has never been shown. A study was conducted with cadavers and volunteers. While the examination of cadavers by ultrasound has been largely unsuccessful, ultrasound studies on the normal volunteers in this study have shown that the method makes it possible to visualize the area of the adductor canal hiatus. Now that the ability of ultrasound to view the area has been proven, further studies now in progress will concentrate on the correlation between constriction of the vessels (e.g., as a result of atherosclerosis) and late vessel disease.