WHAT IS HYPERTENSION?

Liz Corrigan Vascular Programme Advisor

Office of Public HealthDudley MBC

What is blood pressure?

• BP is cardiac output/peripheral resistance i.e. how much blood the heart is pumping out over how much resistance the arteries provide to that blood

• A certain level of BP is necessary for vital organs to function – particularly the kidneys

• BP is measured in millimetres of mercury (mmHg)• Both systolic (top number) and diastolic (bottom

number) are important factors in cardiovascular health and risk

How BP is controlled• Kidneys in particular are very sensitive to changes in BP• If the BP drops the Sympathetic nervous system acts on the heart

to increase output and constricts blood vessels to increase resistance

• In the longer-term, the kidneys release hormones that increase cardiac output and peripheral resistance

• The adrenal glands also release a hormone which encourages the kidneys to retain salt and increases thirst, this increases blood volume

• In the very long-term the kidney releases a hormone which promotes red blood cell production and increases blood volume

• All of this acts to increase blood pressure to ideal levels for that individual

What can influence blood pressure

• BP can be affected temporarily by a number of things• BP rises on waking (there is a fall of 10 – 20% during the

night)• BP usually rises on standing but patterns flatten out

during the day• Short-term stressors e.g. anxiety can cause a rise• BP will rise if the arm is lowered or if the arm is held

rigid during measurement during measurement, and will fall if the arm is raised

• Incorrect BP cuff size can affect results

Equipment

• BP is measured using a sphygmomanometer – this can be automatic or manual

• Automatic machines are simple to use with training and relatively inexpensive (upper arm only!!!)

• Manual measurement requires more in-depth training

• All machines should be regularly serviced and calibrated to ensure accuracy

• Using the correct cuff is important for accurate measurement

Pulse

• Before checking BP you need to measure the person’s pulse manually

• If the pulse is irregular the BP reading you get may not be accurate especially with an automatic machine – you may get an error message instead

• The person will need an ECG • If they are unwell re-direct them to A and E

Measuring blood pressure

• Patient should be seated comfortably with feet flat on the floor

• The arm should be supported and the cuff level with the heart

• Either arm can be used unless the person advises you otherwise e.g. breast surgery

• If the BP is elevated it should be checked again with a gap of no less than 2 minutes

• If the reading is still elevated it should be repeated again at the end of the consultation

High Blood Pressure

• BP persistently ≥140/90 (not a one-off reading)• Either systolic (top number) or diastolic (bottom

number) or both raised• This is known as hypertension and requires

diagnosis and management by the GP• Most people have no symptoms and for most

people there is no known cause• Hypertension is not a disease, but a risk factor

associated with heart disease, kidney disease and stroke

Hypertension assessment required

• If the BP is ≥ 140/90 mmHg it should be re-checked at the GP surgery in no more than 2 weeks

• If the BP is ≥ 160/100 mmHg it should be re-checked in no more than 1 week

• Any diagnoses and decision to treat will be made by the GP

Dangerously high BP• If the BP is 180/110 mmHg as this could be accelerated

hypertension• Accelerated hypertension is a rapid rise in blood pressure

to dangerous levels• There is a high risk of renal or heart failure, stroke due to

damage of the vessel walls, swelling of the brain and brain damage

• Without effective treatment the survival rate is less than 20% i.e. 4 out of 5 individuals will die

• Patients with a BP of 180/110 mmHg need to see a doctor on the same day contact the GP by phone/fax

Any Questions