Patients with postoperative breast cancer often encounter the problem of how to measure blood pressure after surgery on one arm and PICC placement on the other arm. In this case, we usually use the method of measuring the blood pressure of the lower extremities as follows: After 5 minutes of rest, the patient lies on his back with the muscles of the lower extremities relaxed and the pants loosely opened. The cuff is tied flat to the lower thigh, and the middle line of the longitudinal axis of the balloon is pressed on the N artery, with the lower edge 4 cm from the N fossa, and the elasticity is to reach into one finger. The stethoscope chest piece is placed at the midpoint of the N fossa where the N artery contains the strongest pulsation and is in contact with the skin, fixed with the left hand and not tucked under the cuff. Squeeze the balloon with the right hand and gently pressurize it, so that the mercury rises gradually and deflates when the mercury column reaches 200 mmHg, the deflation rate is 2 mmHg per second, so that the mercury column decreases slowly and cannot be re-inflated in the middle, whichever is the case once. The scale indicated by the mercury column when the first beating sound is heard is the systolic pressure, and the sudden disappearance of the beating sound is the diastolic pressure, and the measurement result is the lower limb blood pressure. The diastolic blood pressure of the lower extremity is generally similar to that of the upper arm, but the systolic blood pressure may be 2.7-4.0 kp (20-30 mmHg) higher than that of the upper arm. Here are some more tips on how to measure blood pressure: The internationally accepted standard for measuring blood pressure is to measure blood pressure in the right upper arm for normal people. For the first-time patient, the blood pressure of the left and right upper extremities should be measured separately to make a comparison. If the difference in blood pressure between the two sides is not large (less than 10 mmHg), only the right upper arm blood pressure can be measured later. If the difference in blood pressure between the upper extremities of the patient is more than 10 mmHg, it should be noted that some vascular diseases may exist, such as arterial stenosis or aortitis on the side with low blood pressure. It is also important to measure the blood pressure of the lower extremities. Under normal circumstances, the blood pressure of the ipsilateral lower extremity is generally 20 to 40 mmHg higher than that of the upper extremity, but when the blood pressure of the lower extremity is lower than or equal to that of the upper extremity, it often indicates atherosclerosis, arterial stenosis and other pathologies in the aorta or femoral artery. In addition, once a patient with hypertension feels pain, cramping or coldness in the lower extremities, the blood pressure of the lower extremities should also be measured at the same time as the blood pressure of the upper extremities. If the measurement results show significantly high blood pressure in the upper extremities and low or even no blood pressure in the lower extremities, there may be lesions such as peripheral arterial disease or arterial stenosis. Patients need to go to the hospital for ultrasound scans and other tests to further clarify the condition.