These factors can affect blood pressure! When is the most accurate time to measure blood pressure?

Author: Zhong Jingbai, Chief Physician, Xiyuan Hospital, China Academy of Chinese Medical Sciences

Reviewer: Yang Weibin, Chief Physician, Xiyuan Hospital, China Academy of Chinese Medical Sciences

Vice President of Graduate School of China Academy of Chinese Medical Sciences

The blood pressure of a normal person is not constant, and blood pressure fluctuations are a manifestation of life and health. There are many factors that affect blood pressure, and one of the most important factors is life activities, such as physical activities, psychological activities, etc., which can cause blood pressure fluctuations.

Blood pressure is also affected by external factors, such as changes in climate and humidity in four seasons; some special situations can also affect blood pressure. For example, some people's blood pressure will be higher when they see a doctor in the hospital, while some people's blood pressure will drop a little when they see a doctor.

Normal people's blood pressure fluctuations are generally within a certain range and will not exceed the critical value of hypertension. If you already have high blood pressure, excessive blood pressure fluctuations will have a certain impact on your body.

1. What factors affect the blood pressure of patients with hypertension?

The blood pressure fluctuation pattern of patients with hypertension is actually the same as that of normal people. There are two rhythms, one is called the annual rhythm and the other is called the daily rhythm.

There are 24 solar terms in a year, and eight of them are more important. The "Four Beginnings" are the Beginning of Spring, Beginning of Summer, Beginning of Autumn, and Beginning of Winter. "Beginning" means gradually transitioning to the next season. There are also "Two Equinoxes" and "Two Solstice". "Two Equinoxes" are the Spring Equinox and the Autumn Equinox, and "Two Solstice" are the Summer Solstice and the Winter Solstice. During these eight solar terms, blood pressure is more likely to fluctuate and become unstable due to the influence of the annual rhythm, which is manifested as low blood pressure in summer and high blood pressure in winter.

In terms of daily rhythm, blood pressure is usually higher in the morning and lower in the afternoon and evening, which is called dipper blood pressure. Some people show an abnormal phenomenon, where blood pressure is not high in the morning but higher in the afternoon and evening. This abnormal rhythm is called reverse dipper blood pressure. There is also a type of blood pressure change that does not conform to the above rules, called non-dipper blood pressure.

In addition, the blood pressure of patients with hypertension is also affected by many other factors, the biggest factor being emotions. Many patients have high blood pressure every night, and they do not do much activity at night, but their blood pressure rises at night. In fact, it is a high blood pressure caused by anxiety, which shows that emotions or psychological states have a great impact on blood pressure.

Figure 1 Original copyright image, no permission to reprint

Second, blood pressure fluctuations are related to the time of taking the medicine. If you take antihypertensive medicine at 10 pm, your blood pressure after 10 pm will definitely be better than before 10 pm. If you take antihypertensive medicine at 6 pm, your blood pressure at 7 or 8 pm will definitely be better than that in the afternoon.

Third, blood pressure will also be affected by eating and activities. Blood pressure will rise just after eating or drinking hot tea. If there is activity within half an hour before measuring blood pressure, blood pressure will also be high. Holding urine may also cause higher blood pressure.

These are all factors that affect blood pressure. When measuring blood pressure, these factors should be avoided as much as possible, which can relatively reflect the actual blood pressure level.

2. When is the most accurate time of the day for patients with hypertension to measure their blood pressure?

For patients with hypertension, it is best to keep blood pressure within the normal range, neither too high nor too low. Finding the time periods of high and low blood pressure and taking measures to stabilize blood pressure is beneficial to health.

If your blood pressure is high just after being measured, measure it more times a day. When you measure it three or four times, you will find out which time period your blood pressure is high. Focus on measuring your blood pressure at the time when your blood pressure is high.

If symptoms appear after blood pressure is controlled, measure blood pressure when symptoms appear. If symptoms are obvious when blood pressure is relatively low, blood pressure may have been lowered too much, so you should focus on low blood pressure. If you feel dizzy before going to bed or just lying down, or feel dizzy after get off work at night, etc., you should observe whether it is caused by high blood pressure or low blood pressure.

So measuring blood pressure does not mean that measuring at a fixed time is the most accurate. Measuring at all times is accurate. The purpose is to detect abnormal blood pressure, including high or low blood pressure, so don't stick to measuring blood pressure at one time point.

3. What is the acceptable blood pressure control level for patients with hypertension?

The most ideal blood pressure control state is that the high pressure is below 120mmHg and the low pressure is below 80mmHg. Qualified and ideal are different. Qualified blood pressure is controlled below 140mmHg and below 90mmHg, which refers to the blood pressure measured in the hospital.

Figure 2 Original copyright image, no permission to reprint

When measured at home, the high blood pressure is below 135mmHg and the low blood pressure is below 85mmHg, which is considered qualified. Because through relatively large epidemiological surveys, it is found that the overall trend is that the blood pressure measured at home is slightly lower than that measured in the hospital, about 5mmHg lower. Because when you go to the hospital for medical treatment, there are more psychological activities, and there will be more or less tension and anxiety. The hospital scene is different from the home scene, and the environmental impact when measuring at home is smaller than in the hospital. But there are also individual patients whose blood pressure measured at home is higher than that measured in the hospital, and this situation accounts for a small proportion.

In addition, some elderly people, especially those of advanced age, cannot completely follow this standard. They may not be able to tolerate blood pressure that reaches this standard, which may lead to cerebral ischemia. Doctors need to set a more appropriate blood pressure control level based on the specific situation.

There are two types of blood pressure monitors now, one is a mercury blood pressure monitor and the other is an electronic sensor blood pressure monitor. It is recommended not to buy a mercury blood pressure monitor when measuring blood pressure at home, because without professional training, psychological and physical activities during blood pressure measurement will affect blood pressure; if you are older and have a little hearing impairment, you may mishear blood pressure.

Therefore, it is recommended that ordinary people use electronic blood pressure monitors to monitor their blood pressure at home. The electronic blood pressure monitor must be a qualified one certified by the state or the World Health Organization.