What is Blood Pressure?

The whole world knows and talks about high and low blood pressure. More than 10 million cases of high blood pressure get reported in the country every year and this figure only adds up to the ever increasing estimate of hypertension patients. Though, blood pressure stays to be an important concern for the society, it's not very surprising that a large section of the population is not even good at reading and interpreting their blood pressure test reports.

What is Blood Pressure?

Generally talking, What is Pressure? Pressure is defined as Force per unit Area i.e given a force F and a surface area A over which the force F is applied, pressure P would be equal to F/A. Clearly, Blood pressure is the force exerted by the blood on the walls of the blood vessels(which have some surface area). This pressure if measured too high is called Hyper-tension and if too low it is termed Hypo-tension.

Blood Pressure Reading Interpretation

Blood pressure is measured in mm Hg(millimeters of mercury) where 1 mm Hg is the amount of pressure required to raise a column of mercury liquid 1 mm higher. The instrument used to measure blood pressure is called Sphygmomanometer. We shall talk about it later in this post.

Say, a Sphygmomanometer measures your blood pressure to a reading of 120/80 mm Hg. Now what does that mean? For understanding this, you must be familiar with the following two terms:

• Systolic Pressure : The peak blood pressure recorded when the heart squeezes to pump blood. Here 120 is the systolic pressure.
• Diastolic Pressure : The lowest blood pressure recorded when the heart relaxes after a pump. Here 80 is the diastolic pressure.

Clearly, blood pressure is read as Systolic Pressure/ Diastolic Pressure.

How Does A Sphygmomanometer Work?

You must be knowing that a doctor's Sphygmomanometer has a rubber strap which he ties around the patient's arm. After wrapping the strap, he would use a stethoscope and then following some rise and fall in the mercury column, he would calculate your BP figure. 

Let us see what exactly is the process

The rubber strap is wrapped around the arm and is inflated using the pump till the blood circulation to the arm is cut off. Stethoscope is used to hear the sound of the circulating blood. When the stethoscope becomes silent and hears no pulse sound, it indicates disconnection of blood supply to the arm. The strap should be inflated till the silence in the stethoscope is reached. The actual measurement of BP starts after this point. Now, the strap should be very slowly deflated using the knob fitted in it.

When the very first pulse sound is heard in the stethoscope, the systolic or peak pressure is noted down from the mercury column. This means that the blood supply just got restored. Next, the diastolic pressure is measured when the pulse can no longer be heard. This usually happens at the point of maximum deflation in the strap.

Finally, the ratio of the systolic and diastolic pressure readings give you your blood pressure measurement.

The Salt & BP Relation

It is no hidden fact that a high salt intake is prohibited for Hypertension (High BP) patients. Ever wondered why? 

Only if you knew the function of the kidneys, you would know that they filter the blood for impurities and get them removed. Kidneys also remove extra water and maintain a balance of water to electrolytes(Sodium,Potassium) in the blood. More salt disrupts the natural electrolyte balance of your blood. If you put in more sodium, kidneys will hold in more water. More than an optimal fluid retention exerts more pressure on the delicate blood vessels. In such a case if you reduce your water intake, water from your cells and tissues shall be pulled out and you shall be left dehydrated.

Points to remember :

• Normal Blood pressure 
• Adults
• Systolic (90-120)
•  Diastolic (60-80)
• Infants
• Systolic (95-100)
•  Diastolic (65)
• General Risk factor
• Adults
• Hypertension
• Infants
• Hypotension
• Hypertension is also called 'Silent Killer' due to the fact that it rarely shows up symptoms to be detected and is one of the most important causes of premature death worldwide.

Be regular in your BP checkups