MEDICAL MATTERS/Dr Muiris Houston: Measuring blood pressure must be the most frequent task carried out by family doctors in the course of the working day. Look at any GP's desk and, along with a tendon hammer and a thermometer, a sphygmomanometer will be prominent among the medical equipment.
It takes two measurements: the pressure produced when your heart contracts (systolic pressure) and the pressure produced when the chambers of the heart relax (diastolic pressure). The systolic measurement is recorded above the line, the diastolic below; each is measured in millimetres of mercury (mmHg).
The ideal blood pressure is 120/80. Anything over 140/90 is considered high, although recent guidelines from the World Health Organisation and the International Society for Hypertension have introduced new definitions and classifications for high blood pressure. Normal is now defined as less than 130/85, and high-normal is a systolic of 130-139 and a diastolic of 85-89. Readings above 140/90 are classified as hypertension grade 1, 2 and 3; grade 3 is a blood pressure greater than 180/110.
For years doctors and their patients focused on blood pressure readings in isolation. If the answer to a patient's question, "how's the blood pressure today, doctor?", was "fine" or "normal", it gave the older patient in particular a spring in her step as she left the consulting room. Doctors were trained to make management decisions about blood pressure solely on the basis of two or three readings taken in the surgery.
As the science of hypertension developed, it was realised that acute anxiety temporarily raised blood pressure. So for many people fearful of a visit to the doctor, or those who had raced through traffic to make an outpatient appointment, the concept of "white-coat hypertension" became a reality. Some people have "high" blood pressure in hospital but not in the familiar surroundings of the GP's surgery; others appear hypertensive when checked in the doctor's consulting room but not on a home visit.
The next step forward, which has helped achieve a far more accurate diagnosis of hypertension, was the availability of ambulatory blood pressure monitors (ABPMs). These portable devices allow the recording of blood pressure over 24 hours and so give a more meaningful measurement of the degree and duration of any hypertensive episodes.
With the widespread use of light and reliable portable monitors, it is possible to calculate the degree of blood pressure variation during different activities. A typical working environment adds 13/16 to your blood pressure and attending meetings adds 20/15 mmHg. Talking adds about 7 mmHg to both systolic and diastolic readings while housework adds 11/7 mmHg. Resting is blood pressure neutral; the only activity which lowers readings is sleep - a typical reduction is in the region of 10/8 mmHg.
Average readings calculated from the 24-hour recording are much better indicators of whether to treat or not. Also, it is normal to expect blood pressure levels to drop at night. Research has shown that in those people whose blood pressure does not drop at night - the so-called non-dippers - there is a greater likelihood of the elevated blood pressure causing damage to the kidneys and other organs in the body. This is probably because these patients have higher levels of blood pressure throughout the 24-hour period.
There is also a recognition that hypertension cannot be considered in isolation.
Research has shown that for people with a genetic predisposition to the disease, certain changes take place in the blood vessels early in life. When environmental and cardiovascular risk factors (such as smoking and cholesterol) are added, the disease progresses; the severity of high blood pressure will also drive the rate of damage to blood vessels.
What all this means is that, before launching into the drug treatment of high blood pressure, a doctor must aim to help the patient reduce the risk of complications from hypertension. Stopping smoking, lowering cholesterol and treating diabetes adequately will all contribute to a significant reduction in the risk to the body from hypertension.
Regular walking will directly reduce blood pressure as will losing weight, especially in the tummy. Unlike the effects of acute anxiety, which are temporary, chronic stress raises blood pressure and must be tackled as part of management. Excessive use of salt and alcohol are two other correctable causes of hypertension.
A different approach to hypertension management has been pioneered by the cardiovascular department at Beaumont hospital in Dublin. Prof Eoin O'Brien, consultant cardiologist at the hospital, announced a significant link-up between hospital and primary care last week which signals a new approach to heart disease in the community.
The RHASP Project (Reduction in Heart Attack and Stroke) is based on a computerised model of blood pressure risk management first developed for use in the cardiac clinics at Beaumont.
The days of the desk top sphygmomanometer are not yet numbered; what is different is that it will no longer be the final arbiter in a more holistic and co-ordinated approach to the management of high blood pressure.
Dr Muiris Houston can be contacted at mhouston@irish-times.ie He regrets that he cannot answer individual queries