Importance of Monitoring Blood Pressure

Why should we monitor high blood pressure?

In this essay the reasons why we monitor high blood pressure will be discussed. In order to do this it will first be necessary to explain what blood pressure is and what we mean by high blood pressure. The implications of having high blood pressure will be considered followed by how and why it should be monitored. Both the social and economic implications of high blood pressure and it’s monitoring will be assessed.

Blood pressure is the measure of the force the heart uses to pump blood through the arteries. NHS Choices. (21/07/2014). These arteries manage the flow of the blood by controlling its speed and direction. Blood pressure depends two things; how forcefully the heart pumps the blood and how narrow or relaxed the arteries are. Gill. S, Kristensen. SD. (08/02/2011).

High blood pressure is caused when blood is forced through the arteries at an increased pressure. Artery walls have tiny muscles which allow them to become narrower or wider. The narrower the arteries the less space there is for the blood to flow and the harder the heart will have to work. The muscles in the artery wall react to the flow of blood by working harder, which makes them grow bigger. The wall then becomes thicker reducing the space for the blood to flow through. When the heart has to pump harder to push the blood through narrowed arteries the blood pressure rises. If an artery becomes blocked or bursts, the part of the body that the blood was going to will be deprived of energy and oxygen and will be damaged or die. In this instance the pressure of the blood causes the damage. Fullick. A (2008).

Arteries can become damaged in other ways. They can become hardened (atherosclerosis) as a result of fat, cholesterol and other substances building up in the walls of the arteries. Hence life style can be a major contributor in high blood pressure. If an individual is overweight, smokes, eats too much salt, doesn’t exercise enough and, or consumes too much alcohol they will be susceptible to high blood pressure. In addition, if a person has relatives with high blood pressure, has a history of cardiovascular disease, or is of African or Caribbean descent they are more prone to it. Finally, as a person gets older so does their chance of getting high blood pressure, as the blood vessels become stiffer and less flexible. NHS Choices. (04/07/2014).

Having continued high blood pressure (also known as hypertension) increases a persons risk of many serious illnesses, for example; cardiovascular disease, stroke, embolism, aneurysm and kidney disease, to name a few. Approximately one in five people in the UK suffer from hypertension. Gill. S, Kristensen. SD. (08/02/2011). However many of these aren’t aware, as there are not always obvious symptoms. For this reason it is sometimes known as the silent killer. NHS Choices. (04/07/2014). In some instances, with continued levels of very high blood pressure, individuals may display persistent headaches, blurred or double vision, nosebleeds and shortness of breath. The only way to know if a person has a problem with their blood pressure is to get it measured. The NHS recommend that every adult should have their blood pressure checked every 5 years. NHS Choices. (04/07/2014).

The chart opposite shows the different levels of blood pressure and at what point they are considered low, normal and high. This chart is suitable for adults of any age as, although a persons blood pressure might change with age, the levels at which the pressure is considered high, normal or low do not. Blood Pressure Association . (2008).

When taking a person’s blood pressure there are two readings. The top number is the systolic blood pressure. This is the highest pressure when the heart beats and pushes blood around the body. The bottom number is the diastolic blood pressure. This is the lowest pressure when the heart is relaxed between beats. Low blood pressure is anything less than 90/60. Ideal blood pressure is between 90/60 and 120/80. Readings up to 140/90 mean that the blood pressure is a little high and should be reduced slightly but anything over 140/90 is an indication of high blood pressure. Only one of either the systolic or diastolic numbers has to be higher than it should be to indicate that a person has high blood pressure . Blood Pressure Association . (2008). If blood pressure is 120 diastolic or below the risk of cardiovascular disease as a result of blood pressure is minimal but as it rises up to 140 diastolic the risk doubles and then by 160 over it doubles again. For every 20mm diastolic increase the risk of death from cardiovascular disease doubles. Blood Pressure Association. (2008).

Figures published by Public Health England in November 2014 showed that diseases caused by continued high blood pressure cost the NHS over £2bn every year and monitoring accounts for 12% of all GP visits. £850 million could be saved over a period of 10 years if overall blood pressure was reduced. In addition, over the same period of time, if 15% more people were diagnosed, a further £120 million could be saved. Finally, if another 15% currently being treated controlled their blood pressure more effectively, another £120 million could be saved. Public Health England. (2014).

However, the act of measuring blood pressure is problematic. The whole process of going to visit a G.P to have your blood pressure monitored can in itself increase blood pressure. This is commonly known as the white coat effect; where a blood pressure reading is higher when taken in a medical setting than when it’s taken at home. This may be because patients are more nervous in such settings. It is reported that such an increase may occur in as many as 25% of those diagnosed with high blood pressure. This can lead to improper diagnosis of high blood pressure. NHS Choices. (24/08/2011). NICE (National Institute for Health and Care Excellence) reports that this effect is more common in pregnancy and with increasing age. McManus. R et al (2011). Thus other methods of monitoring are being considered more widely. One of these methods is ambulatory blood pressure monitor (ABPM). This is where blood pressure is measured for up to 24 hours. A small digital blood pressure monitor is secured around a patients waist and connected to a cuff at the top of their arm. It is small enough not to affect daily life and can even be used when asleep. It measures the blood pressure at regular intervals over 24 hours, so a doctor is able to get a clear idea of how a patient’s blood pressure changes throughout the day. It avoids the problem of misleading spikes in blood pressure because a patient is feeling anxious about being tested.

Pickering found that 21% of 292 patients with borderline high blood pressure actually had normal daytime readings. These patients were defined as having “white coat” hypertension, and they were more likely to be female, younger and to weigh less. Pickering. TG et al (1988). Staessen undertook a similar study and found that more patients measured by ABPM stopped treatment than those measured in a medical setting. Staessen. JA et al (1997). Therefore the benefits to large portions of society who might be able to stop taking drugs as a result of mis-diagnosis could be quite substantial.

ABPM is, however, expensive. In 2011 NICE released the findings of a study that found that although it was the most accurate method of diagnosing hypertension, it was also the most expensive. However, the savings made as a result of reduced cost of drugs and GP visits meant that it was still the most cost effective means of measuring and confirming diagnosis. McManus. R et al (2011). Staessen also found that drug intervention could be reduced and that blood pressure and overall general health was improved as a result of treatment based on ABPM reading. Staessen. JA et al (1997). Therefore the social and economic benefits of ABPM would appear to be wholly worth the cost.

However, Law, Wald and Morris Law. M, Wald. N, Morris. J. (2003). suggest there are problems with restricting the measurement of blood pressure purely to those with high blood pressure. They argue that although blood pressure is an important cause of stroke and heart disease it is not a good screening test to distinguish who will or will not develop them. They claim that most strokes and coronary heart disease occurs in people who do not have high blood pressure (only 10% of people with the highest blood pressure experience less than one third of all strokes and one fifth of all coronary heart disease events) and that older people with average blood pressure have a substantially greater risk than younger people with high blood pressure.They suggest that the term hypertension intimates that blood pressure is a disease in itself, rather than an indication of more serious problems and that monitoring with a view to reducing high blood pressure ignores those whose blood pressure might be relatively normal or borderline but whom for other reasons may develop stroke or heart disease. They found that lowering blood pressure reduces the risk of heart disease and stroke whatever the starting blood pressure. They suggest that the main method of screening should be to identify all those with a history of stroke or heart attack. They further suggest that there is little point in measuring blood pressure after a first event as subsequent deaths account for about half of all deaths from stroke and heart disease.

Surprisingly, Law, Wald and Morris suggest that changes in diet and lifestyle have only a limited effect in reducing average blood pressure, although they do acknowledge that a major reduction in the salt content of manufactured foods by the food industry would have an impact. They argue that blood pressure lowering drugs are the only way to ensure substantial reductions in blood pressure. As such they suggest that blood pressure reducing drugs should be given to all those identified as susceptible to heart disease or stroke, including those over a certain age, regardless of the level of their blood pressure.

The impartiality of Law, Wald and Morris findings are questionable as they see medication as the only way forward. It is not clear if their research is funded by a pharmaceutical company and care would need to be taken when relying upon their findings. They give no credence to the social benefits of life style changes, for example general well being from a reduced diet or alcohol intake, as well as the benefits brought about from the socialising aspect of exercise. Their recommendations also take no account of the reluctance of otherwise healthy individuals to a lifetime of drug taking. As highlighted by Honigsbaum, Honigsbaum. M.. (2012). who, at the age of 47, living a healthy life style, rejected the notion of having to take pills for the rest of his life. Honigsbaum is an example of those in Law’s study, whose life style did not suggest a problem with high blood pressure but whom had a genetic pre disposition to the condition.

In conclusion, it would appear that there is consensus of agreement that high blood pressure is a major world health problem and that monitoring is essential. However, there is still a lot to be done in terms of education about lifestyle and adoption of values that underpin this, for example encouragement of healthier lifestyles and for the food industry to take take responsibility for a reduction in salt in manufactured foods. There is further a growing body of agreement that ambulatory blood pressure monitoring is the most effective in terms of diagnosis and as such the higher costs are justified. In addition, questions remain regarding how to identify those with pre existing or inherent predisposition to cardiovascular disease who may not have high blood pressure.

References

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Pickering. TG, James. GD, Boddies. C, Harshfield. GA, Blank. S, Laragh. JH.. (1988). How common is white coat hypertension?. National Institute of Health. 259 (2), 225-8.

McManus. R, Jowett. S, Barton. P, Hodgkinson. J, Mant. J, Martin. U, Heneghan. C, Hobbs. R.. (2011). Cost-effectiveness analysis – blood pressure monitoring for confirming a diagnosis of hypertension. Hypertension. 1 (1), 446.

Staessen. JA, Byttebier. G, Buntinx. F, Celis. H, O’Brien. ET, Fagard. R.. (1997). Antihypertensive treatment based on conventional or ambulatory blood pressure measurement. A randomized controlled trial. Ambulatory Blood Pressure Monitoring and Treatment of Hypertension Investigato. National Institute of Health. 278 (13), 1065-72.

Law. M, Wald. N, Morris. J.. (2003). Lowering blood pressure to prevent myocardial infarction and stroke: a new preventive strategy. Health Technology Assessment NHS R&D HTA Programme. 7 (31), 3.

Honigsbaum. M.. (2012). Home truths about high blood pressure. Available: http://www.theguardian.com/society/2012/jan/08/high-blood-pressure-mark-honigsbaum. Last accessed 30/01/15.

Fullick. A (2008). Edexcel AS Biology. Essex: Pearson Eduction limited. 18-33.

Public Health England. (2014). Tackling high blood pressure from evidence into action. Available: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/375985/20141018_Tackling_high_blood_pressure_-_FINAL_INCL_LINK_CHANGES.pdf. Last accessed 30/01/15.

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