How to measure blood pressure correctly (using mercury sphygmomanometer), especially how to measure low pressure accurately?

Open the box first and turn on the switch of the silver mercury tank at the bottom of the mercury column.

1. Subjects straighten their elbows and palms at the same level as their hearts.

2. Place the stethoscope on the brachial artery to make the fourth costal cartilage level. Wrap the cuff around the middle of the upper arm (elastic enough for one finger), and the lower edge of the cuff is 2-3cm away from the elbow socket.

Squeeze the balloon to pump air until the beating sound of brachial artery disappears, and the mercury column rises again for 20-30mmHg, and then slowly deflate to make the mercury column drop, and the line of sight is parallel to the mercury column scale.

3. The first sound heard in the stethoscope, the scale indicated by the mercury column is systolic blood pressure; When the pulsatile sound disappears or weakens, the scale is diastolic pressure.

4. After measurement, release the air in the cuff and untie the cuff. Blood pressure measurement is complete.

After the test, turn the sphygmomanometer 45 to the right, close the valve and put the balloon in a fixed position to avoid crushing the glass tube.

Systolic blood pressure/diastolic blood pressure is 120/80mmhg.