2. 血管阻断试验：研究对象左上肢轻度外展，将无创血压计袖带按正确测量

2. 血管阻断试验：研究对象左上肢轻度外展，将无创血压计袖带按正确测量血压方法置于上臂肱动脉处，先测定无创血压，知晓动脉收缩压后充气袖带加压至收缩压上30 mmHg（1 mmHg = 0.133 kPa）阻断前臂血流，3 min后快速释放袖带压力，在缺血再灌注过程中持续监测并记录PPI的变化。左臂如因“对象中排除标准④”而不能用者，则启用右臂。

2. Blood vessel blocking test: the subject's left upper limb was slightly abducted. The non-invasive sphygmomanometer cuff was placed at the brachial artery of the upper arm according to the correct blood pressure measurement method. The non-invasive blood pressure was measured first. After knowing the arterial systolic pressure, the inflatable cuff was pressurized to 30 mmHg above the systolic pressure (1 mmHg = 0.133 kPa) to block the blood flow of the forearm, and the cuff pressure was released quickly after 3 minutes, The changes of PPI were continuously monitored and recorded during ischemia-reperfusion. If the left arm cannot be used due to the "exclusion standard ④ in the object", the right arm will be enabled.

2. Vascular occlusion test: The left upper limb of the research object was slightly abducted. The cuff of the noninvasive sphygmomanometer was placed at the brachial artery of the upper arm according to the correct method of blood pressure measurement. First, the noninvasive blood pressure was measured. After knowing the arterial systolic pressure, the inflatable cuff was pressurized to 30 mmHg(1 mmHg = 0.133 kPa) above the systolic pressure to block the blood flow of the forearm. After 3 min, the cuff pressure was quickly released, and the change of PPI was continuously monitored and recorded during the ischemia-reperfusion process. If the left arm can't be used because of "Exclusion Standard ④ in Objects", the right arm is enabled.