Firstly, what is blood pressure?
Blood pressure is the force that our blood exerts on our arteries. This force is constantly fluctuating as the heart beats. When the heart contracts, blood pressure reaches it maximum force. This is called systolic blood pressure. When the heart relaxes between beats the force of the blood is lower. This is called diastolic blood pressure.
Blood pressure varies throughout the day. Many activities (such as exercise, eating, stress) can also effect blood pressure.
As our lives become increasingly automated, there is a shift to use an automated blood pressure device.
The advantages of an automated blood pressure monitor apart from convenience is the removal of human bias and human error. The downside from an increasing use of automated blood pressure devices, is the chance that our skills with using a manual device become a little rusty.
So this is a quick refresher on how to measure blood pressure using a manual (aneroid or mercury column) blood pressure device.
First, choose the right device and equipment. You will need
- A blood pressure measurement device such as an aneroid or mercury column sphygmomanometer.
- Note that measuring blood pressure at the upper arm is preferable to wrist or finger measuring devices
- An upper arm cuff to fit adults or a smaller cuff to fit children
- A stethoscope
Prepare to take blood pressure measurement.
- Ensure the patient is relaxed, sitting comfortable and free of restrictive clothing that may impede measurement
- Ideally patients should have rested for 5 minutes before measurement and avoided caffeine or smoking for 30 minutes prior to measurement.
- Have the patient sit upright with the upper arm approximately level with the heart.
- Choose the appropriate cuff size for the upper arm.
- Talking should be minimised during the measurement.
Place the cuff on the upper arm
- Locate the brachial artery pulse and place the blood pressure cuff so that the artery marker points to the brachial artery.
- Wrap the cuff around the arm so it is snug against the arm.
Position the stethoscope
- On the same arm the cuff is placed, palpate the arm at the antecubical fossa (elbow pit) to find the strongest pulse and place the bell of the stethoscope over the pulse at this location
Inflate the cuff
- Begin inflating the cuff placed around the arm by compressing the rubber bulb. Continue to listen to pulse through the stethoscope.
- When the cuff has inflated enough to stop blood flow you should hear no sound through the stethoscope. This will typically be 30-40 mmHg above the person’s normal blood pressure measurement (if that is known).
Slowly deflate the cuff
- Slowly release pressure in the cuff by releasing the pressure value.
- Ideally pressure should fall 2-3mmHg per second. Any faster may result in an inaccurate measurement
Listen for the systolic reading
- The first occurrence of rhythmic sounds heard as blood begins to flow through the artery is the patient’s systolic blood pressure.
Listen for the Diastolic reading
- Continue to listen as the cuff pressure drops and the sounds fade. Note gauge reading when the rhythmic sounds stop. This will be the diastolic reading.
Double check for accuracy
- If time permits, it is recommended to take a reading from both arms and average the reading.
- Also take into account that blood pressure is typically higher in the morning and lower in the evening
- If there is concern about the possible accuracy of the measurement in the clinic, then a 24 hour measurement period may be required.
MedQuarters has a range of aneroid sphygmomanometers, digital blood pressure monitors and stethoscopes to enable blood pressure measurement. Clink on the link below to see our range