Measurement
Baseline BP is established by taking two to three BP readings per visit (while the patient is sitting) on up to four occasions.
Aims of Treatment
To reduce diastolic BP to less than 85 mmHg and to reduce systolic BP to less than 140 mmHg, but the optimal target in people with diabetes or kidney disease is lower. In the elderly, the threshold for treatment is usually higher, as research only shows consistent benefits in treating a BP that is persistently raised to 160/90 or greater.
Target Organ Damage
This is defined as left ventricle of heart enlarged; angina; transient ischaemia attacks (TIAs); stroke; peripheral vascular disease; heart attack; kidney function impaired.
DRUGS USED TO TREAT HYPERTENSION
At present, six classes of drug are available to lower high blood pressure:
If a single drug is not effective, other anti-hypertensive drugs may be added, usually at intervals of at least four weeks, until good control of BP is achieved. Where hypertension is relatively mild (systolic BP less than 160mmHg, and diastolic less than 100mmHg), drugs may be substituted rather than used together.
Thiazide Diuretics
Thiazide diuretics (e.g. bendrofluazide, hydrochlorothiazide) are generally used as a first-line treatment in the elderly, or are combined with other anti-hypertensive drugs (e.g. a beta-blocker or ACE inhibitor) to boost their action in younger patients.
They lower blood pressure by increasing loss of salts through the kidneys into the urine. This tends to draw fluid out of the circulation, causes mild dilation of small arteries and lowers arteriolar resistance. The diuretics act within an hour or two of being given and are usually taken in the morning so you do not have to get up at night to pass water. When you first start taking the tablets, you may notice that you have to pass water more frequently than usual for the first few days;, then this effect tends to disappear as dilation of the arterioles occurs. Only low doses of hiazide diuretic are needed to bring your diastolic BP down by around 5 mmHg – higher doses have no further effect on BP and are more likely to cause side effects such as salt imbalances.
They should not be used by people with diabetes or with sodium, potassium or calcium imbalances, severe kidney or liver problems, active gout or Addison’s disease.
Beta-blockers
The way beta-blockers lower blood pressure is not fully understood but is thought to result from a combination of actions in which they:
In general, beta-blockers are used as a first-line treatment in young people with hypertension and in people who have coronary heart disease. Because they also affect receptors in the lungs, they should not be used in people with asthma as they may trigger an asthma attack. Beta-blockers have been shown to significantly reduce the risk of having a second heart attack and may prolong life in high-risk individuals.
Beta-blockers should not be withdrawn suddenly, but must be tailed off slowly so that rebound high blood pressure (or angina) does not occur.
Alpha-blockers
Alpha-blockers (e.g. doxazosin, indoramin, prazosin, terazosin) lower blood pressure by dilating both arteries and veins. They are particularly helpful for older males who have both high blood pressure and problems associated with benign enlargement of the prostate gland. They sometimes