Sphygmomanometer for measuring blood pressure

In 1628, William Harvey (English scientist) noticed that when an artery was cut, blood gushed out as if driven by pressure. By touching the pulse beat, the blood pressure would be felt .

In 1733, a priest named Hayes took the first measurements of blood pressure in animals. He used a glass tube with a small metal tube at the end and a length of 270 centimeters to insert it into the carotid artery of a horse, and the blood immediately flowed into the glass tube as high as 270 centimeters, which means that the blood pressure in the horse's carotid artery can be maintained at 270 centimeters, and that the height will be slightly raised or lowered due to the horse's heartbeat, and that the blood pressure rises during contraction (systolic blood pressure) and falls when the heart relaxes (diastolic blood pressure).

In 1835, Julius Ericsson invented a sphygmomanometer that transmitted a pulse beat to a narrow column of mercury. When the pulse beat , the mercury would bounce up and down accordingly. For the first time, doctors were able to measure pulse and blood pressure without cutting into an artery. But because it was difficult to use, crude, and gave inaccurate readings, other scientists improved it.

The sphygmomanometer measures blood pressure based on the height of a column of mercury, and the barometer measures air pressure in the same way.

In 1860, Etienne-Jules Mare (a French scientist) developed one of the best sphygmomanometers of its time. It magnified the pulse beat and recorded the path of the beat on a roll of paper. The sphygmomanometer was also portable. Marey used the sphygmomanometer to study abnormal heartbeats.

The sphygmomanometer used by doctors today was invented in 1896 by Gipione Riva Rocchi, an Italian scientist. It has an inflatable cuff to stop the flow of blood. Doctors use a stethoscope to listen to the pulse while reading the blood pressure on a scale.

(Note: The first sphygmomanometers were used to measure the blood pressure of horses. Over the years, sphygmomanometers have become more and more advanced, and many people have them in their homes to keep track of their health. The principle of measurement of sphygmomanometer can be divided into direct measurement and indirect measurement.

Direct measurement is also called invasive measurement, that is, through a puncture in the blood vessels after the placement of catheters to measure the blood pressure, such as cardiac intervention in the diagnosis and treatment of invasive blood pressure to monitor the patient. The invasive method is used to measure blood pressure directly. Because of the different parts of the body that are measured, the methods vary and do not fully reflect the body's blood pressure.

Indirect measurement, also known as noninvasive measurement, is the measurement of blood pressure indirectly, not through a puncture after placing a catheter in a blood vessel.

Indirect measurements can be divided into auscultation and oscillometry.

1, auscultation method

Using a stethoscope to listen to the blood pressure Koch's tone for human blood pressure measurement method called auscultation method, with the auscultation method of blood pressure measurement of blood pressure sphygmomanometer is called auscultation method of sphygmomanometer. Such as mercury sphygmomanometer, blood pressure meter. For more than a hundred years, people have been exploring more reliable methods and instruments for blood pressure measurement, but they are unsuccessful, including the oscillometric method electronic sphygmomanometer, therefore, our regular hospitals have to continue to use mercury sphygmomanometers, developed countries in Europe and the United States have banned the use of mercury sphygmomanometers due to environmental reasons, and their health care institutions use blood pressure meters. Faced with the fact of successive failures, there are people in the international arena who call the auscultation method the gold standard of blood pressure measurement. Hundreds of years of history has proved that the auscultation method is irreplaceable, and that the auscultation sphygmomanometer is a scientific, classic blood pressure measurement and measuring instrument.

Classification of auscultation:

The auscultation sphygmomanometer is divided into manual auscultation sphygmomanometer, semi-automatic auscultation sphygmomanometer and automatic auscultation sphygmomanometer. Artificial auscultation method sphygmomanometer common mercury sphygmomanometer and blood pressure meter; semi-automatic auscultation method sphygmomanometer with readable sphygmomanometer; automatic auscultation method sphygmomanometer with auscultation automatic sphygmomanometer.

1, artificial auscultation method sphygmomanometer is to use mercury and so on as a manometer, the measurement of the human ear through the stethoscope to listen to the original blood pressure Koch sound (from heavy to light, and then disappeared or tone), and according to hear the Koch sound with the manometer to read out the systolic and diastolic blood pressure; auscultation method method, although it is currently the most accurate method of measuring blood pressure, but the artificial auscultation method is affected by the following factors: (1) (1) the level of training received; (2) hearing; (3) attention; and (4) poor visualization at the time of judgment. Blood pressure measurement is reliable or not is completely determined by the professional level of the measurer, hearing, fatigue and work attitude, but also because the blood pressure is an instantaneous value, unrepeatable, no composite, the measurer said how much is how much. 2, semi-automatic auscultation method sphygmomanometer is similar to the stethoscope like an electronic probe, listen to the blood pressure Koch sound, and through the electronic technology of the volume amplification, in the sphygmomanometer next to the people can hear rhythmic chirping blood pressure Koch sounds (all equally heavy sounds), and reading systolic and diastolic blood pressures based on the heard Koch sounds in conjunction with the manometer. This method excludes (1) the level of training received; (2) hearing; (3) attention and other influences, but still subject to the judgment of the witnessing of the difference in the impact, it although it can make more people use it to measure blood pressure, but there are still a part of the people feel that the use of the very troublesome. 3, fully automated stethoscopic method of sphygmomanometer is to be similar to the same as the stethoscope electronic probe, listen to the blood pressure Koch sound, and through modern digital technology to the blood pressure Koch sound into a digital signal, and finally displayed on the display of the sphygmomanometer, that is, to realize the automation of blood pressure measurement. This sphygmomanometer also has semi-automatic and fully automatic points: manual pumping, automatic deflation called semi-automatic; automatic pumping, automatic deflation called fully automatic. This sphygmomanometer does not receive training in the level, hearing, attention and judgment of the witnessing difference in impact, everyone can use it to accurately measure blood pressure.

2, oscillometric method

Oscillometric method, also known as the oscillometric method, is a more advanced electronic measurement method developed in the 1990s.

The principle is briefly described as follows:

First of all, the cuff is tied to the arm, the cuff is automatically inflated to a certain pressure (generally higher than the systolic blood pressure of 30~50 mmHg) and then stops pressurizing and starts to deflate, when the gas pressure is up to a certain level, the blood flow will be able to pass through the blood vessels and there is a certain amount of oscillating wave, the oscillating wave spreads through the trachea to the pressure sensor, and the pressure sensor detects the pressure and fluctuation inside the measured cuff in real time. The pressure sensor can detect the pressure and fluctuation inside the cuff in real time. The pressure sensor detects the pressure and fluctuations in the cuff in real time. Gradually deflate the cuff and the oscillating wave becomes larger. With further deflation, the pressure and fluctuations detected by the pressure sensor become smaller and smaller as the contact between the cuff and the arm loosens. The point of maximum fluctuation was chosen as the reference point, and based on this point, the point of peak fluctuation of 0.45 was searched forward, which is the systolic pressure, the point of peak fluctuation of 0.75 was searched backward, which corresponds to the diastolic pressure, and the point of highest fluctuation corresponds to the mean pressure. It is worth mentioning the constants 0.45 and 0.75. This varies from manufacturer to manufacturer and should be based on the results of clinical tests. Also, large manufacturers may segment different blood pressures and set different constants.

Internationally, several technologically advanced companies have developed pressurization synchronous measurement technology (MWI technology), which is the technology to measure blood pressure during pressurization, greatly shortening the measurement time; at the same time, through the linear pressurization technology, it also greatly improves the measurement accuracy. Electronic sphygmomanometers are divided into two categories according to the place of use: medical electronic sphygmomanometers and household electronic sphygmomanometers.

Medical electronic sphygmomanometer, mainly used in hospitals, outpatient clinics, blood stations, blood collection trucks, medical examination vehicles, health management physical examination centers, rehabilitation centers, nursing homes, communities, schools, banks, factories, sports stadiums and other public **** health.

Home electronic sphygmomanometer, mainly used in the family. Family health care has become a modern health care fashion. In the past, people must go to the hospital to measure blood pressure, but now as long as they have a home electronic sphygmomanometer, sitting at home at any time to monitor changes in blood pressure, such as blood pressure abnormalities can be found in time to go to the hospital for treatment, and play a role in the prevention of cerebral hemorrhage, cardiac failure and other sudden onset of disease. According to the international legal measurement organization put forward international recommendations "sphygmomanometer revised draft regulations", sphygmomanometer scale change millimeters of mercury (mmHg) for the dry Pa (kPa). 1kPa = 7.5mmHg, the scale on the graduation value is 0.5kPa. blood pressure meter on two scales, please pay attention to the application. There are 3 forms of electronic sphygmomanometers, one is the arm type, the second is the wrist type, and the third is the finger type. Of these three types of electronic blood pressure monitors, the finger-type electronic blood pressure monitors have been proven to be unusable even for healthy people. It is necessary to make it clear that wrist-type electronic blood pressure monitors are not suitable for patients suffering from blood circulation disorders, such as diabetes mellitus, hyperlipidemia, hypertension and other diseases that will accelerate arteriosclerosis, thus causing peripheral circulation disorders. The difference in blood pressure measurement between the wrist and the upper arm of these patients is very large. It is recommended that these patients and the elderly should choose an arm-type electronic sphygmomanometer for use. In addition, you should take measurements on the spot before purchasing, so that you can choose an electronic sphygmomanometer that suits your needs.

First of all, the technology of electronic sphygmomanometers has gone through two stages of development in terms of the principle of using the auscultation method (also known as the Koch sound method) and the oscillometric method (also known as the oscillometric method), with only a very small number of companies using the auscultation principle for electronic sphygmomanometers, and the vast majority of the mainstream electronic sphygmomanometer manufacturers using the oscillometric principle.　Given the current mainstream use of the Oscillometric principle, the technological generation that will be discussed here is that of the Oscillometric (also known as Oscillometric) electronic sphygmomanometer.

The first generation of electronic sphygmomanometers (G1-NIBPM)

Technology used: MWD technology (measurement during depressurization)

Main components used: fast-pressurizing air pumps, electronic fast-expiratory valves, mechanical fixed-speed exhaust valves, and barometric pressure sensors

Measurement characteristics: fast pressurization to a certain pressure value, and a mechanical fixed-speed exhaust valve to press 2 to 7 mm to release the pressure. A mechanical exhaust valve is used to release air at a rate of 2-7 mmHg/s, and blood pressure is measured during this release.

Feature 1: Two exhaust valves are used: an electronic quick exhaust valve (------) and a mechanical fixed-speed exhaust valve;

Feature 2: Initial pressurization pressure is mostly set at about 200 mmHg, with the emphasis on fast pressurization, which is usually achieved in less than 10 seconds;

Feature 3: The deflation rate is more than 7 mmHg/s when pressurization stops and can only be approximated after a few seconds.

Feature 3: When the pressurization just stops, the deflation speed is more than 7mmHg/s, and can be stabilized at 2~7mmHg/s after a few seconds. Due to the instability of the mechanical fixed-speed venting valve of the current generation of products (the principle of defects), the initial pressurization pressure will be increased, such as the majority of domestic sphygmomanometers, and the initial pressurization pressure is mostly set at 190~200mm Hg, which to a certain extent can overcome the unstable measurement caused by the deflation speed when the pressurization is just stopped.

This is to some extent to overcome the unstable measurement caused by the deflation rate when the pressure is just stopped.

The disadvantage is that the user's arm (or wrist) feels a distinct sense of pressure, and the measurement results are sometimes unstable due to the instability of the mechanical fixed-velocity exhaust valve.

The second disadvantage of the mechanical fixed-speed exhaust valve is that its exhaust speed is usually set according to the medium-sized arm, while the actual user's arm is either thick or thin, thus affecting the accuracy of the measurement.

The third disadvantage of mechanical speed vents is that the rubber starts to deteriorate in about six months to a year, which affects the manufacturer's setting of the exhaust speed, and ultimately the accuracy of the measurement.

The fourth disadvantage of mechanical fixed-speed exhaust valves is that, even for the same measurement on the same subject, the exhaust speed is faster when the pressure is high and slower when the pressure is low. This directly affects the accuracy of blood pressure measurements.

This generation of sphygmomanometer technology was discontinued by most Japanese manufacturers more than a decade ago. However, some domestic manufacturers that have purchased electronic sphygmomanometer solutions are at the first generation of technology. And all the solution providers have only this generation of technology in hand.

The second generation of electronic sphygmomanometers (G2-NIBPM)

Technology used: MWD technology (Measurement during depressurization)

Main components used: pressurized air pumps, electronically controlled venting valves, and barometric pressure sensors

Measurement features: Due to the use of electronically controlled venting valves with ECV SERVO TECHN OL OGY, the fixed pressure is measured at a constant rate. OL OGY), the speed of the fixed-speed exhaust is truly fixed, and intelligent pressurization can be carried out according to the blood pressure of the person being measured, which makes the measurement results more stable (in addition to other influencing factors).

Feature 1: Only one exhaust valve is used: ------- electronically controlled exhaust valve, which is used for both fixed-speed exhaust and rapid exhaust at the end of the measurement;

Feature 2: Intelligent pressurization. That is, the sphygmomanometer will be in the process of pressurization Prior to the measurement of the blood pressure of the patient to make a rough judgment, so as to determine the final need to add to the pressure value, usually the pressure value to the measurement of the patient's systolic blood pressure +30mmHg or so; Characteristics of the 3: the deflation rate can be stabilized in the beginning on the 3~4mmHg/s. The blood pressure monitor can be used to measure the blood pressure of the patient.

The technical difficulty of this generation of electronic sphygmomanometers is the servo technology of the electronically controlled venting valve, and the measurement technology of the first and second generations is collectively called MWD technology (measurement during decompression), which corresponds to the third generation of MWI technology (measurement during pressurization) as described below.

Third Generation Electronic Blood Pressure Monitor (G3-NIBPM)

Technology Used: MWI Technology (Measurement During Pressurization)

Main Components Used: Servo Pressurization Pump, Electronically Controlled Air Venting Valve, Air Pressure Sensor

Measurement Characteristics: Uniformly Rapid Pressurization, and Measurement of Blood Pressure during the Pressurization Process.

Feature 1: A servo-pressurized air pump ------ is used to control the pressurization rate and to measure blood pressure during pressurization;

Feature 2: Only a single air venting valve ------ is used, an electronic quick exhaust valve, which is used to quickly vent the air at the end of the measurement.　The technical challenge of this generation of electronic sphygmomanometers is the MWI technology (simultaneous measurement during pressurization), which is mastered by the following international companies: Gemini, Omron, Panasonic.

The third generation of electronic sphygmomanometer technology

MWI technology (pressure measurement) has become the mainstream of wrist electronic sphygmomanometer technology, gold Yidi, Omron, Panasonic, etc. has eliminated the previous measurement technology.

On the use of three generations of electronic sphygmomanometer technology

Judging from the products of the world's leading electronic sphygmomanometer manufacturers, the first generation of electronic sphygmomanometer technology is basically on the brink of obsolescence; the second generation of electronic sphygmomanometer technology is used in upper-arm electronic sphygmomanometers; and the third generation of electronic sphygmomanometer technology is mainly used in wrist-type electronic sphygmomanometers.

Difference between third-generation and first- and second-generation sphygmomanometers

The third-generation sphygmomanometers are very different from first- and second-generation sphygmomanometers. The third-generation electronic sphygmomanometer measures blood pressure during pressurization, without the process of slow exhaust, and exhausts quickly immediately after the blood pressure is displayed. The first and second generation electronic sphygmomanometers are pressurized quickly to a certain pressure and then begin to deflate slowly, measuring blood pressure during the slow deflation process.

Differences between first- and second-generation sphygmomanometers

The difference between first- and second-generation sphygmomanometers is that the first-generation sphygmomanometers use two exhaust valves, the ------ electronic rapid exhaust valve and the mechanical fixed-speed exhaust valve, whereas the second-generation sphygmomanometers use a single exhaust valve, the ------- electronically-controlled exhaust valve, which is used for both fixed-speed and rapid exhaust at the end of the measurement. This valve is used for both fixed-speed exhaust and rapid exhaust at the end of the measurement.

See the figure below:

According to the pressurization method of the electronic sphygmomanometer, the electronic sphygmomanometer can be divided into fully automatic electronic sphygmomanometer and semi-automatic electronic sphygmomanometer.

Semi-automatic

In the early days of sphygmomanometers, there were semi-automatic sphygmomanometers ------ that were manually pressurized. Although most manufacturers have discontinued the production of semi-automatic sphygmomanometers, it is important to analyze their shortcomings. When using a semi-automatic sphygmomanometer for self-measurement of blood pressure, manual pressurization will affect the blood pressure of the subject and hence the accuracy of blood pressure measurement! Of course, if a third party helps with the pressurization, there is no problem with the accuracy of the blood pressure measurement.

FULLY AUTOMATIC

In contrast to semi-automatic sphygmomanometers, fully automatic sphygmomanometers were developed ----- - that is, sphygmomanometers that do not require manual pressurization by the patient, but rather are pressurized by an electronic pressurizing pump inside the sphygmomanometer. Fully automatic sphygmomanometers have overcome the disadvantages of semi-automatic sphygmomanometers. In addition, we have developed the "Intelligent Pressurization Technology for Electronic Sphygmomanometers" on this basis.

Intelligent pressurization

Intelligent pressurization means that the electronic sphygmomanometer, during the pressurization process, will make a rough judgment on the systolic blood pressure of the measurer in advance, so as to decide the pressure value that needs to be added to in the end, which is usually added to the systolic blood pressure of the measurer of about +30mmHg. Intelligent pressurization technology is mainly used in the second generation of electronic sphygmomanometers. The opposite of smart pressurization is fixed pressurization.　Fixed pressurization means that the initial pressurization value of the sphygmomanometer is set at a fixed position, usually around 190 mmHg. Fixed pressurization technology is mostly used in the first generation of electronic sphygmomanometers.

What are the benefits of smart pressurization

First of all, it's comfortable because there's no excessive pressure applied to the arm. For example, a person with a systolic blood pressure of 120 mmHg can be pressurized to about 150 mmHg. Secondly, it is accurate. Intelligent pressurization avoids the discomfort associated with high pressurization, which can cause instability in blood pressure measurements, and thus avoids affecting the accuracy of the measurement. Lastly, it is quiet, because smart pressurization technology requires the use of a quiet air pump, and noisy air pumps cannot be used with smart pressurization sphygmomanometers. Therefore, using an electronic sphygmomanometer with smart pressurization technology will be more comfortable for the user and the measurement results will be more accurate.

What's difficult about smart pressurization technology

The difficulty lies in the fact that it is necessary to predict the systolic blood pressure of the person taking the measurement while pressurizing, and that the air pump interferes a lot during pressurization, which makes it difficult to detect the signal of the blood pressure, and therefore smart pressurization technology is only available from a few manufacturers that have the third-generation technology of electronic sphygmomanometers, ------ pressurization synchronization measurement (MWI) technology.

Reader-assisted

In the early 21st century, scientists further improved the traditional mercury sphygmomanometer, the modern electronic sphygmomanometer, and developed the more practical and simpler reader-assisted sphygmomanometer, which took sphygmomanometers to a new level of development. Compared with other sphygmomanometers, the read-assist sphygmomanometer has the following significant features:

1. Accurate measurement. The Sphygmomanometer adopts the only method of measurement recognized by the International Health Organization (WHO), which is known as the Kirchhoff's method of measurement, for accurate measurement.

2. Simple to use, no need to take off clothes and roll up sleeves. The reading-assisted sphygmomanometer can be used to measure directly through clothing up to 2cm in thickness, eliminating the need for the user to undress and roll up the sleeves.

3. The electronic tone indicates the blood pressure value. During measurement, there is an electronic tone between high and low pressure, the first tone corresponds to high pressure, and the last tone corresponds to low pressure.

4. Indicates other health conditions. The electronic beeps emitted by the sphygmomanometer during measurement accurately reflect the heart's beat. If the tone is rapid, it means that the heart is beating too fast; if the tone is delayed, it means that the heart is beating too slowly, and through the analysis of the tone, we can judge the early stage of the disease such as arrhythmia; if the value of high pressure is too close to the value of low pressure, it means that the blood viscosity is too high; if the tone is appeared every few seconds, the person who takes the measurement may be suffering from an intermittent heart disease.

5. Compared with the traditional electronic sphygmomanometers, the reading-assisted sphygmomanometers are cheaper and have a longer service life.