Hypertension- Know how to measure your Blood Pressure
In my last blog, I had discussed the various causes of hypertension. Today we learn how to measure B.P. and the different types of instruments used to measure it. The first one [Fig.1] is Mercury sphygmomanometer which is the gold standard of B.P.measurement and a widely used one by doctors all over the world.
The second one [Fig.2] is the called Aneroid barometer and is a good portable one. The third one [Fig.3] is an electronic one-Digital BP apparatus– which needs to be calibrated and is also highly accurate and used mostly as a home measurement unit. The fourth one [Fig.4] is the Wrist B.P. measuring unit which is mostly used in obese people.
How do you Measure Blood Pressure to know if you have Hypertension-
On purchasing one of the BP apparatus, you have to attach the cuff of the instrument to your upper arm and inflate it either manually[in case of Mercury or Aneroid BP apparatus] or by pressing the start button on a digital/wrist instrument, as shown in Fig.2, then release the air. Then put a stethoscope in the crotch of your elbow in case of the first 2 instruments [as shown below]. This is done by another person, either your family physician or your relative. After releasing the air slowly from the cuff, you can observe manually on Mercury Sphygmometer by hearing the sounds with a stethoscope applied at the crotch of your elbow. The reading at which you start hearing the sound is called Systolic BP and the reading at which the sound disappears is called the diastolic BP. For eg. if you hear the sound at 120, this is the systolic BP and if the sound disappears at 80, this the diastolic BP. In short, this will be recorded as 120/80 mm of Hg[Hg stands for mercury].
Similarly, in the case of a digital BP apparatus, you do not need a stethoscope to hear the sounds. Simply press the start button after connecting the cuff to the arm and instrument as in Fig.3 and the instrument will record the BP and your pulse rate also and report it after the cuff deflates fully.
To get one of these instruments, just click here
Measurement of Blood Pressure-
In hypertension, the most important part is its measurement. As shown in the picture above, you have to
- Bind the cuff above your elbow joint with the tubings either in the middle of the elbow or on the inner side of the elbow.
- Next, inflate the cuff using the pumping bulb attached to the tubing. This will inflate the bladder inside the cuff, compressing the artery, called the brachial artery, above the elbow.
- The other tubing which is attached to the BP machine will cause either the mercury to rise in the mercury sphygmomanometer or the pointer to move upward in the aneroid BP Apparatus. In the case of a digital apparatus, the recording will be shown directly.
- Next, you have to deflate the bladder by releasing the pumped up pressure.
- As you release the pressure, a sound will be heard of heart-pumping- this is called Kortakoff sounds and indicates the Systolic pressure. This the sound of the heart pumping blood.
- After releasing the pressure further, the sounds will disappear. This is called the Diastolic pressure- the pressure of the heart relaxing.
Why does BP rise in Hypertension?
Both the Systolic and Diastolic pressures rise due to-
- Aging- as the arteries lose their elasticity
- High cholesterol levels- causing deposits of cholesterol in the walls of the artery thereby narrowing the internal size of the artery. This makes it more difficult for the heart to pump blood thereby causing a rise in BP.
- Chronic kidney disease(CKD)- Kidneys release some hormones that control our BP. These become less as the kidney disease progresses. Vice- versa, hypertension can also damage the kidney causing CKD.
You can also listen to this podcast for getting a better insight at measuring BP at home and controlling it-