The problem for all concerned is that patients suffer few, if any, symptoms and therefore don’t take responsibility for measuring or monitoring their blood pressure. As they’re unaware of their condition they don’t tend to report symptoms until there is a reason to be concerned. When symptoms do present themselves, it is often at an acute emergency stage.
The majority of deaths associated with the condition can be explained by a lack of accurate treatment – or indeed any treatment. Only around a quarter of cases are treated.
Once diagnosed, it’s essential that sufferers measure their blood pressure on a regular basis, taking notes and monitoring changes. That way they can detect emergencies at an early stage and prevent further damage.
Ambulatory and at-home blood pressure monitors allow patients to get an accurate diagnosis of their hypertension statistics so they know when to seek medical help and when to make necessary lifestyle changes.
How do blood pressure monitors work?
Blood pressure monitors are non-invasive and pain-free. An inflatable cuff is put around the upper arm and that is attached to a pressure monitoring device. There are two ways of measuring blood pressure:
- Oscillometric measurement devices
With these devices the cuff is either fitted on the wrist (with the arm elevated to heart height) or the upper arm. The cuff is inflated and released by an electronically-operated pump and valve. The device uses an electronic pressure sensor to read out a numerical value. Once the blood flow is present, but restricted, the cuff pressure will vary periodically in synchrony with the cyclic expansion and contraction of the brachial artery. The values of systolic and diastolic pressure are computed from the raw data, using an algorithm.
- Auscultatoric measurement devices
These also use an inflatable cuff, placed around the upper arm at roughly the same vertical height as the heart. After the cuff is inflated and pressure is slowly released, and blood starts to flow in to the artery again. The turbulent flow creates a pulse synchronic pounding (first Korotkoff sound). The pressure at which this sound is first detected is the systolic blood pressure. The cuff pressure is further released until no more sound can be detected at the diastolic arterial pressure.
Creating the right environment
Choosing the right monitor
Blood pressure monitors are only medically viable if they are reliable, correct and exact. Equally, they must be used correctly in the right conditions.
Monitors for home use have, at the very least, to bear the CE label although this is not a guarantee that they have been clinically tested.
Home monitors tend to be oscillometric. For patients that need a very precise result, auscultatoric measurement is more accurate but is usually only used by doctors.
For double safety, monitors exist that perform both testing methods (the Korotkoff method used by doctors and the oscillometric method), resulting in reliable results even under special conditions.
Achieving the most accurate readings
The accuracy of measurement depends on a number of factors. For example:
- The body’s posture. For a wrist device the elbow should be bent slightly and the monitor held in chest-height (same level as the heart). For upper arm devices the arm should be relaxed and placed on the table.
- The environment. Stress will make blood pressure rise so the situation must be as relaxed as possible. Ambulatory blood pressure monitoring provides a more reliable measure of a patient’s blood pressure, as patients don’t experience the ‘white-coat effect’, which can overestimate readings, particularly in susceptible patients. However, clinical measurement of blood pressure is useful for screening and in the management of suspected and true hypertension.