Blood pressure

Why does the patient’s/client’s blood pressure need to be checked?

Blood pressure is the force the blood exerts on the walls of the blood vessels as it’s pushed through the body by the heart. Its importance to health is now well-recognised, in that high blood pressure can lead to serious illnesses like strokes, heart disease and kidney disease. There is also an extreme form of high blood pressure that can happen to pregnant women and which can be fatal for woman and baby. So the best way we can detect high blood pressure early is to check the patients/clients in our care.

When should I check it?

The blood pressure should be checked as part of routine initial checks of temperature, pulse and respirations. This sets a baseline against which we can compare changes. We should be mindful, though, that people accessing a health service for the first time can feel quite stressed, and stress causes a rise in blood pressure, so our first reading might be misleadingly high. You should always check a high first reading some time later, after the person has relaxed a bit. Note also that other factors, such as recently smoking a cigarette or taking a high quantity of alcohol, can also raise the blood pressure temporarily.

The frequency of checking will vary according to the person’s general health state. People who are obese (a cause of high blood pressure) or who have a history of high blood pressure should be checked frequently. Some people who are undergoing investigations for high blood pressure might be attached to a machine that measures the pressure continuously over a 24-hour period. The times to check the blood pressure will be set out in the patient’s/client’s care plan.

How do I check it?

Have a look at our slide show on how to take a blood pressure reading.


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Measuring blood pressure

Allow the person to rest for at least five minutes while you gather the equipment for taking their blood pressure. They should be relaxed and not moving or speaking. In this example, a manual sphygmomanometer is being demonstrated. Ensure you explain the procedure to the person and gain their consent before taking their blood pressure.

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Measuring blood pressure

Make sure the person's arm is supported at the level of the heart and free of any restrictive clothing. Locate the brachial artery as demonstrated.

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Measuring blood pressure

Apply the pressure cuff so the arrow is over the brachial artery and fits snugly - the bladder of the cuff should cover at least 80 percent of the arm (but not overlap by more than 100 percent).

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Measuring blood pressure

Ensure there is enough space between the cuff and the elbow for the bell of the stethoscope. Estimate the systolic reading by: palpating the brachial artery; inflating the cuff until pulsation disappears and noting this reading; deflating the cuff again.

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Measuring blood pressure

Place the diaphram of the stethoscope over the brachial artery. It should not make contact with the cuff as this will add pressure to the brachial artery and interfere with hearing the blood pressure (Korotkoff's) sounds you are listening for and give an inaccurate reading.

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Measuring blood pressure

Pump the cuff up to a pressure about 30mmHg above the estimated systolic blood pressure level Slowly deflate the cuff at a rate of about 2mmHg/second until regular tapping sounds are heard.

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Measuring blood pressure

The 'systolic' reading is the pressure at which the pulsations are first heard as the cuff deflates. The 'diastolic' reading is the pressure at which the pulsations have completely disappeared after the cuff has deflated. Record the blood pressure reading in the person's record to the nearest 2mmHg. Remove and clean the equipment and perform hand hygiene. Report any abnormal results to a registered nurse immediately.


What do my findings mean?

‘Normal’ blood pressures vary widely, but generally a blood pressure that is persistently raised above 140/90 is considered high blood pressure.

The problem is that high blood pressure – called hypertension – isn’t easily recognised by physical means. There is no rash or swelling, and the person doesn’t complain of pain or discomfort; in fact many people just go about their daily business unaware that they have hypertension. For that reason, it has sometimes been called ‘the silent killer’.

The opposite of hypertension is low blood pressure, or hypotension. This generally isn’t a problem if it is the person’s natural state, but a sudden and unexplained hypotension could be very serious and must be reported immediately. Also, some people with hypotension feel dizzy or may even faint if they get to their feet too quickly, so must be taught to do so gradually.

Where should I record and report my findings?

As you’ll have seen from our slideshow on how to take a blood pressure reading, the blood pressure consists of two separate sounds, and these must both be recorded.

Some people with hypertension will monitor their own blood pressure and may have a recording book. You should make sure the readings are recorded in their book as well as your organisation’s own observation chart. You should make sure you record your findings clearly and accurately so that they can be readily seen and understood. Always follow your organisation’s policies and procedures on recording and reporting.

You can find more information on the British Hypertension Society website.

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