YOUR HEALTH - MEDICINE 101

Blood Pressure

So how is your blood pressure?

We all know that having your blood pressure checked is an important part of any medical examination , but what exactly is blood pressure and how do you measure it?

Your blood pressure is simply a measurement of the force (or pressure) that’s pushing blood through the arteries in your body. Your heart does the pumping. It creates the pressure to make the blood flow out through the arteries by rhythmically contracting. Boom boom. Simply put, the heart is a circular muscular pump and each time the muscles of the heart contract they shoot out a volume of blood into the arteries. This jet of blood, this extra volume of blood shot out into the system produces a wave or peak of pressure that flows down the artery. You can feel that wave or pulse of pressure going down. That’s what you’re feeling when you take your pulse. Now, with blood pressure, we measure both the heart during a contraction and at rest. Boom boom. Boom boom. The Greek for contracting is systolo, that’s where we get the term systolic pressure. That’s the top number. Now, when the heart relaxes and fills with blood in anticipation of the next contraction or the next beat, the pressure within the arteries falls. It relaxes. The Greek word for relaxation is diastolo, and that’s the bottom number, called diastolic pressure. So the normal blood pressure is in the range of 120 to 140 systolic and 70 to 80 diastolic. Or 120 over 70.

Let me take my own blood pressure and show you how we do it.

I put the cuff around the arm above where the brachial artery comes close to the surface. It’s near the inside of the elbow. You pump the balloon and that squeezes air into a bladder thingy inside the cuff. This increases the pressure in the arm and this pressure squeezes shut the elastic walls of the artery flowing into the arm so that no blood flows past the inflated cuff. Then the cuff is slowly deflated while the doctor listens over the artery. As soon as the artery opens and blood from the heart flows through again the doctor hears a soft tapping sound and reads the pressure from a hand held dial. That’s the systolic pressure, the pressure of the wave of blood sent out by the contraction of the heart. As the doctor keeps listening and keeps lowering the pressure in the cuff the tapping sounds disappear - that’s theresting, or diastolic pressure.

Blood pressure is usually recorded in millimeters of mercury and pressures are not always the same in each arm. Too high a pressure (or tension) is called hyper tension and puts you at risk for heart disease and stroke. Too low a blood pressure (hypotension) is seen in conditions of dehydration or shock and may indicate that not enough blood is flowing to vital organs.

Blood pressure is an important vital sign. The next time you are in the office and the cuff is squeezing your arm, ask the doctor if she can hear the little tap, tap tap….