All About Blood Pressure: Methods and Readings
Walk into your family doctor’s office for a physical examination. Of the many tests that may be performed, your blood pressure will almost certainly be checked. This is because blood pressure is a well-known measurement of cardiovascular health that gives insight into the inner workings of your heart, and your overall state of health.
When your heart beats, pressure is exerted both in the vessels in the heart and in the arteries, delivering blood, oxygen, and nutrients to the body. Between heartbeats, the heart rests and importantly, this pressure level drops. Blood pressure measurement, which is measured in “millimeters of mercury” or mmHG, shows you if these pressure levels are acceptable or if there may be cause for concern.
In this article, we will discuss more about blood pressure readings, including risks associated with prolonged elevated blood pressure. We will also talk about the different methods of measuring blood pressure, and whether any particular method has proven superior. We will delve further by exploring other related markers of cardiovascular health. Let’s begin.
Blood Pressure: Systolic and Diastolic
Take a seat in your doctor’s office. A cuff is placed around your arm and a blood pressure reading is taken, consisting of two numbers, one normally larger than the other. A typical blood pressure reading is recorded as a systolic pressure first (shown on top) and diastolic pressure second (shown on bottom), with your total blood pressure reading given as a result. These two numbers paint of picture of the forces being placed upon your heart and the blood vessels within your body.
Systolic pressure, the typically higher number in the reading, measures the force (or pressure) that your heart exerts with each heartbeat. Diastolic blood pressure, or the typically lower number in the reading, measures the force that is placed upon your heart while it is at rest (or between beats). Both of these numbers are important and give you and your health practitioner valuable insight into your heart health. These numbers are used to classify your blood pressure range as anywhere from “Normal” to “Stage 2 Hypertension”. We will discuss more about blood pressure ranges later on.
Why Monitor Blood Pressure?
As we have discussed, blood pressure is an important marker of cardiovascular health, but just what does that mean exactly? Commonly referred to as the “Silent Killer” , high blood pressure is often asymptomatic. Occasionally, a person may suffer from headaches or vomiting as a result of high blood pressure, however for most people, symptoms of high blood pressure are rare and thus high blood pressure may go undetected. Prolonged high blood pressure increases your risk for developing a number of other health conditions including:
Heart attack: High blood pressure can damage arteries and prevent blood flow to the heart muscle.
Stroke: Elevated blood pressure promotes your risk of stroke due to clotting in the arteries or potential bursting of the blood vessels.
Kidney disease: High blood pressure can stress kidneys and negatively affect their ability to filter.
Sexual Dysfunction: Erectile dysfunction and libido problems have been linked to high blood pressure.
Angina: High blood pressure can lead to heart disease and chest pain, otherwise known as angina.
Peripheral Artery Disease: Narrowing of the arteries, often caused by atherosclerosis, can cause pain in arms, legs, stomach and head, and may increase your risk for other cardiovascular diseases.
High blood pressure when high for too long, creates stress on your blood vessels. Bad cholesterol, or “LDL cholesterol”, may accumulate in weaknesses or tears in the artery walls, promoting atherosclerosis and potential clot formation. The heart then, in essence, must work harder to pump blood throughout the body, therefore increasing your risk for a variety of cardiovascular and cerebrovascular events. Regularly monitoring your blood pressure and following up with your healthcare practitioner with any concerns are important steps in protecting that very valuable heart muscle and other essential organs.
Blood Pressure Measurement: The Basics of Measurement
Blood pressure is typically taken in the upper arm, over the brachial artery. Although this may seem straightforward and simple, a variety of methods of blood pressure measurement exist.
This method uses a mercury sphygmomanometer (or blood pressure cuff) and is typically regarded as ‘gold standard’ for in office blood pressure measurement. Typically used in the clinical setting, a cuff is placed around the upper arm, is inflated, and then the practitioner uses a stethoscope and listens for what is known as ‘Korotkoff’ sounds, or the sounds of pulsatile blood flow as the cuff is deflated.
This method of blood pressure measurement is less common than it once was due to a wide-spread ban on mercury sphygmomanometers, due to the risks associated with the usage of mercury. Hybrid devices have been developed which combine both electronic and auscultatory methods, replacing mercury usage with an electronic pressure gauge. These devices require proper training of the health practitioner and frequent calibration to ensure the accuracy of blood pressure measurements.
The Oscillometric Technique forms the basis for home blood pressure monitors and other electronic monitors used in various settings. As the blood pressure cuff is gradually deflated during usage, the oscillations recorded by the device begin at approximately systolic pressure and continue below diastolic pressure. Blood pressure is then estimated empirically, using a specific formula. This method has been found to be comparable to the auscultatory method, and may present a number of advantages as well.
Convenience: This technique makes home-usage and out of clinic usage possible, reducing the need for regular measurement by a healthcare practitioner.
Elimination of practitioner error: A major advantage as there is no reliance on proper training of blood pressure measuring techniques, including factors such as selecting the right cuff size and position, recognizing subject factors such as anxiety, proper use of the auscultatory method using a stethoscope and correct recording.
Elimination of white coat syndrome: The presence of a medical doctor taking blood pressure has been identified as a factor influencing higher blood pressure readings.
Multiple Readings: Allows for a higher number of readings daily, which is ideal for regular monitoring of blood pressure.
For those with high blood pressure, the American Heart Association recommends “home monitoring for all people with high blood pressure”. This allows for regular monitoring and reporting to your healthcare practitioner. A single elevated reading is not typically cause for concern, but home monitoring allows you to easily and regularly check your readings yourself, promoting better heart health.
How to Measure Blood Pressure Correctly
A number of factors can affect your blood pressure reading. According to the American Heart Association, you should not smoke, drink caffeinated beverages or exercise for 30 minutes prior to taking a blood pressure reading. Five minutes of rest and an empty bladder are recommended before commencing a blood pressure check. You should be seated in a supported chair, with your feet flat on the floor and your arm should be supported on a surface at heart level. Blood pressure should typically be taken at the same time every day, such as morning and evening, and you should take two to three readings at a time, spaced by a minute apart.
Blood Pressure Readings
There are five blood pressure ranges recognized by the American Heart Association. These ranges should best be utilized in terms of consistent readings at these levels, as opposed to one isolated reading. It is important to distinguish that these ranges use the words “and” and “or” specifically:
Normal Blood Pressure: Less than 120 mmHg systolic and less than 80 mmHg diastolic.
Elevated Blood Pressure: 120-129 mmHg systolic and less than 80 mmHg diastolic.
Hypertension Stage 1: 130-139 mmHg systolic or 80-89 mmHg diastolic.
Hypertension Stage 2: 140 mmHg or higher systolic or 90 mmHg or higher diastolic.
Hypertension Crisis: If your blood pressure suddenly exceeds 180/120 mmHg, wait five minutes and then test your blood pressure again. Contact your doctor immediately your blood pressure remains in this range.
Both systolic and diastolic blood pressure matter. For those over the age of 50, typically systolic blood pressure is given more weight as a major cardiovascular risk factor. This is because the systolic blood pressure will generally rise with age as arteries naturally stiffen and as a result of long-term plaque build up. Research however describes that the risk of death from ischemic heart disease and stroke doubles for every pressure increase of 20 mmHg systolic or 10 mmHg diastolic in those aged 40-89.
Further interpretation of your readings
As we have discussed, to lower your risk of various health conditions, it is important to know your blood pressure scores and to monitor and contact your health professional if readings are consistently abnormal.
The BPBIO 320S, by InBody USA, is a fully automated and easy to use oscillometric blood pressure monitor that is voice guided, has a single-step measurement process, and has an elbow sensor for more accurate results with high reproducibility. This device has met the requirements of the European Society of Hypertension International Protocol validation protocol, showing that it can be recommended for clinical use in adults. The BPBIO 320S measures Systolic Blood Pressure, Diastolic Blood Pressure, Pulse Pressure, Mean Arterial Pressure, Pulse Rate and Rate Pressure Product.
We have already discussed systolic and diastolic blood pressure in detail. Pulse Pressure (PP), which is the difference between systolic and diastolic blood pressure, and Mean Arterial Pressure (MAP), which is the average pressure in the arteries during a cardiac cycle, are well established markers of cardiovascular health.
In a large study of 2311 subjects with essential hypertension, 24 hour blood pressure monitoring showed that PP is a major predictor in cardiac events and that MAP is a major predictor in cerebrovascular events. In addition, both PP and MAP have been found to be associated with ischemic stroke in hypertensive individuals.
Rate Pressure Product, which is an indicator of oxygen requirements of the heart, has been used to assess cardiovascular fitness and the risk of coronary artery disease.
Know Your Numbers!
It is important to be aware of your blood pressure score, as blood pressure is a reliable indicator of cardiovascular health. High blood pressure is associated with a number of health risks and making a habit to regularly monitor your blood pressure is a healthy one!
Oscillometric blood pressure devices have made it easier than ever to check your blood pressure regularly, lessening the reliance on that once a year physical examination and putting you more in control of your health.
Normal blood pressure, defined as less than 120/80 mmHg, combined with other markers of cardiovascular health such as Pulse Pressure, Mean Arterial Pressure and Rate Pressure Product, give valuable insight into your current health and potential risk level. Should you have blood pressure readings that are consistently abnormal, be sure to monitor and discuss these results with your health professional.
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