What is sphygmomanometer?
A sphygmomanometer is an instrument which is used to measure blood pressure. It is also known as blood pressure meter and blood pressure gauge sphygmomanometer.
What does a sphygmomanometer consist of?
Sphygmomanometer consists of an inflatable cuff, a measuring unit and a mechanism for inflation that may be a bulb or valve which is operated manually or a pump which is electrically operated.
Types of sphygmomanometer
There are two types of sphygmomanometer:
- Manual sphygmomanometer
- Digital sphygmomanometer
Manual sphygmomanometer is of two types which are mercury sphygmomanometer and aneroid sphygmomanometer. Mercury sphygmomanometers are considered to be the gold standard as they observe the blood pressure by observing the height of a column of mercury while aneroid sphygmomanometers are of mechanical type which comes with a dial.
How to measure blood pressure using a sphygmomanometer?
Here are a few steps which would help you learning how to use a manual sphygmomanometer to check blood pressure level in human body:
Arrange the apparatus
You will need a stethoscope for accurate and complete blood pressure reading. Before starting using the device you need to make sure that all the parts of the apparatus are fastened and connected in a secure and proper way.
Place the cuff
Now bring your arm on the level of your heart and place the cuff of the sphygmomanometer midway between the shoulder and the elbow with a gap of 2-3cm above your elbow. Locate the brachial artery pulse with first two fingers and place cuff so the arrow of the arterial indicator is directly over the brachial artery. You arm should remain at the same height as your heart.
Cuff should neither too loose nor too tight
Place the cuff by keeping this thing in mind that it should neither be loose nor tight because if it will be loose it will not be able to compress the artery in right manner and won’t give you an accurate reading of your blood pressure. If it will be too tight it will give you an inaccurately high reading which is called as cuff hypertension.
Place the stethoscope
Now place the eartips of the stethoscope in your ears and the chestpiece of it over the brachial artery which is underneath the cuff.
Inflate the cuff
Now is the time to inflate the cuff. Screw the valve clockwise to shut the air release valve and inflate the cuff around 20-30 mm above the systolic pressure. Pump until the needle (in case of aneroid sphygmomanometer) or the mercury (in case of mercury sphygmomanometer) reaches 180mmHg or little above. The pressure from the cuff will occlude a large artery in the bicep, temporarily cutting off blood flow. This is why the pressure from the cuff can feel a little uncomfortable or strange.
Release the valve
Now gently turn the valve on the bulb counter-clockwise, so that the air in the cuff is released steadily, but at a slow pace. Keep an eye on the gauge; for best accuracy, the needle should be moving downwards at a rate of 3mm per second
It may be little tricky to hold the stethoscope while releasing the valve. Release the valve with the hand on your cuff arm by holding the stethoscope with your free hand. If there is someone near you, you may ask for their assistance.
Read systolic pressure
When you open the valve, the pressure starts dropping and a thumping or knocking sound starts coming from the eartips of the stethoscope. When you listen the first sound, note the reading on the dial or the mercury column. This is your systolic pressure.
Read diastolic blood pressure
Keep your eyes on the gauge and keep listening the thumping sound. Thumping noise turns into a different sound which helps in noticing the change which shows that you are close to the diastolic blood pressure. And then you listen no sound. Not the reading where the sound stops. This is the diastolic blood pressure.
It is totally acceptable you miss the measure of either number. You can start again from step number 5 and take the readings again. Normal blood pressure is when tour systolic blood pressure is 120mmHg and diastolic pressure is 80mmHg.