Acute lower limb ischemia requires the following tests: 1. Examination Limb elevation test (Buerger’s test) The patient lies flat, the affected limb is elevated 45°, and after 3 minutes, observe the change of skin color of the foot; then let the patient sit up, the lower limb hangs next to the bed, and observe the change of skin color. If the skin of the toes and sole is pale or waxy yellow after elevation, and the skin of the foot is flushed or patchy cyanosis after dropping, it is called a positive result. 2.Auxiliary examination Generally, thrombo-occlusive vasculitis can be diagnosed based on medical history and physical examination. The following auxiliary examinations can help to further clarify the site, extent, nature and degree of arterial occlusion and the establishment of collateral circulation. (1) Skin temperature measurement under certain room temperature (15-25℃), the limb temperature decreases more than 2℃ compared with the corresponding part of the opposite side, which indicates that the blood supply of that side limb is insufficient. (2) Infrared thermogram Infrared thermography can detect the infrared radiation from the surface of the limb and convert it into a thermogram. At the same time, the temperature of each sampling point can be expressed numerically. The infrared thermogram of the limb in thrombo-occlusive vasculitis can show a darker glow in the ischemic area of the affected limb and an abnormal “cold zone”. (3) Segmental manometry and stress test Segmental manometry provides information about the arterial systolic pressure of each segment of the limb. Thrombo-occlusive vasculitis often manifests as a decrease in blood pressure below the popliteal or brachial artery of the affected limb. If the lesion is limited to the lower extremity, the ankle/brachial index (normal value ≥1) reflects the severity of ischemia in the affected extremity. If segmental manometry is normal, stress tests such as exercise test and reactive congestion test can be used. Ankle pressure decreases significantly after stress test in patients with early thrombo-occlusive vasculitis, and ankle pressure recovery time is prolonged. (4) Pulse wave tracing using Doppler flow velocimetry and various volumetric tracers can trace the arterial waveform of each segment of the limb. The distal arterial waveform of the affected limb in thrombo-occlusive vasculitis is often unidirectional, with low amplitude and low blunt peaks. In severe lesions, the arterial waveform is a straight line. (5) Arteriography arteriography can clarify the site, extent, nature and degree of arterial occlusion, and can understand the establishment of branch circulation in the affected limb. Arteriography in thromboembolic vasculitis typically shows segmental occlusion of small and medium-sized arteries, while normal arteries with smooth walls can be seen between the diseased arteries. In addition, many small collateral vessels are often seen. Because arteriography is an invasive test that can cause arterial spasm and endothelial damage, aggravating limb ischemia, it is generally not used as a routine test for this disease.