Blood Pressure – the ‘real’ story


One of the mandatory tests at my hospital when you see a doctor is a blood pressure reading, usually denoted as “BP”.  Now I take blood pressure tablets to keep my BP within the normal range, which they do (provided I take them)!

For many reasons, including forgetfulness, I had not taken any for over a week.  When I remembered I had forgotten, I popped into one of the Out Patients Clinics and got the nurse to take my BP.  It was 158/87.  Too high.  I need to remember to take my tablets!  However, about 30 minutes later I had my BP checked again.  This time 147/76.  Much better, but still marginally up.  How could this be?  Was the machine wrong?

No, the machine was not wrong, but what you have to understand is that BP is not a constant, but fluctuates for many reasons – rushing, coffee, anxiety, cigarettes and a whole host of others.  This is why, if your doctor tells you that you have “hypertension” (high BP) on just one reading – don’t believe him (or her).

So how do you find out if your BP is too high?  Quite simply by repeated measurements.  Just as one swallow doesn’t make a summer, one elevated reading does not necessarily mean hypertension.

As part of the routine in most good hospitals and clinics is the measurement of your blood pressure.  You should get this done at least twice a year.  Rising or elevated readings do mean you should get medical advice.

So why is BP important?  Because if you don’t you don’t have BP you are definitely dead!  However, if your BP is too high, it can mean you could be claiming early on your life insurance policy – or your relatives will, on your behalf.

High BP is otherwise known as the “silent killer” as there are very few symptoms of the increase in blood pressure, until a vessel bursts somewhere, generally catastrophically!  The good thing is you are dead within minutes, so you won’t linger.

Blood Pressure is needed to keep all the organs of the body supplied with oxygen.  This is done by the red blood cells which carry the oxygen, with the pump to drive the system being the heart.  The tubes from the heart heading outbound are the arteries, and those returning the blood to the heart are the veins.

This heart-arteries-veins-heart system is a “closed” circuit.  In other words, no leaks, otherwise you would be continually losing the life-preserving blood, but to make it go around, there has to be a pumping pressure (just like the oil pump in your car).

The heart squeezes the blood inside itself and pumps it out into the arteries.  This squeezing pressure is called the Systolic, and is the upper number quoted when we measure your blood pressure.

After the squeeze, the heart relaxes to allow the blood to fill the chamber, ready for the next squeeze.  The pressure does not return to zero, because there has to be some pressure to refill the chamber.  This resting or ambient pressure is the lower number quoted and is called the Diastolic.  BP is then typically quoted as 120/70, being 120 (systolic) / 70 (diastolic).  The actual pressure number is measured in a millimeters of mercury scale.

So what is the correct BP?  The following table shows the categories of BP measurements.

Optimal: less than 120/80

Normal: less than 130/80

High-normal: 130–139/85–89

High blood pressure (hypertension):

Stage 1: 140–159/90–99

Stage 2: 160–179/100–109

Stage 3: 180 or higher/110 or higher

The problem with running at high pressure is that the heart is having to work harder, and therefore may be subject to heart failure.  The arteries are also subjected to higher pressures than they were designed to cope with and can burst, making the risk of stroke so much higher.  Other organs don’t like working at the high pressures either, and kidneys, in particular, can go into failure mode.

No, if you really have hypertension, get it treated – but remember to have repeated measurements done, and don’t let the doctor classify you as being “hypertensive” until repeated measurements confirm that your BP is too high.