Blood Pressure (second part): Classification

Normal values

While average values for arterial pressure could be computed for any given population, there is often a large variation from person to person; arterial pressure also varies in individuals from moment to moment. Additionally, the average of any given population may have a questionable correlation with its general health, thus the relevance of such average values is equally questionable. However, in a study of 100 subjects with no known history of hypertension, an average blood pressure of 112/64 mmHg was found,[15] which is in the normal range.

In children the normal ranges are lower than for adults.[16] In the elderly, blood pressure tends to be higher than normal adult values, largely because of reduced flexibility of the arteries. Factors such as age, gender and race[citation needed] influence blood pressure values. Pressure also varies with exercise, emotional reactions, sleep, digestion and time of day.

Differences between left and right arm blood pressure measurements tend to be random and average to nearly zero if enough measurements are taken. However, in a small percentage of cases there is a consistently present difference greater than 10 mmHg which may need further investigation, e.g. for obstructive arterial disease.[17] [18]

The risk of cardiovascular disease increases progressively throughout the range of higher arterial pressure that begins at 115/75 mmHg.[19] In the past, hypertension was only diagnosed if secondary signs of high arterial pressure were present, along with a prolonged high systolic pressure reading over several visits. In the US, this reactive stance has been soundly rejected in light of recent evidence. However in the UK, patients’ readings are still considered normal up to 140/90 mmHg.[20]

Clinical trials demonstrate that people who maintain arterial pressures at the low end of these pressure ranges have much better long term cardiovascular health. The principal medical debate concerns the aggressiveness and relative value of methods used to lower pressures into this range for those who do not maintain such pressure on their own. Elevations, more commonly seen in older people, though often considered normal, are associated with increased morbidity and mortality. The clear trend from double blind clinical trials (for the better strategies and agents) demonstrates that lower arterial pressure correlates with lower rates of disease.[citation needed]


from wikipedia.org