As a cardiologist, the sphygmomanometer is one of the most common aids we use. But how much do we actually know about blood pressure monitors? Before we start reading this article, we would like to ask seven questions, if these questions are also ambiguous in your mind, you are welcome to discuss and share. 1.Which is more accurate, the electronic blood pressure monitor or the mercury column blood pressure monitor? 2.Why is the use of electronic blood pressure monitors recommended in the Chinese guidelines for the prevention and treatment of hypertension? 3.What is the basic principle of blood pressure measurement of commonly used electronic blood pressure monitor? 4.What are the types of commonly used electronic blood pressure monitors? 5.Which is more accurate, the upper arm type or wrist type electronic sphygmomanometer? 6.How to ensure the accuracy of electronic sphygmomanometer measurement? 7.What are the precautions when using the electronic sphygmomanometer? A, electronic sphygmomanometer and mercury column sphygmomanometer, which is more accurate? As we all know, the accurate measurement of blood pressure depends on the arterial catheterization method, but its use is limited, only in the cardiac catheterization procedure, as a means of detection. Other commonly used non-invasive blood pressure measurement methods, including oscillometric (electronic sphygmomanometer) and auscultatory (mercury column sphygmomanometer) methods, are only as close to the true blood pressure as possible. Therefore, in terms of accuracy, many clinicians are wrong to assume that the blood pressure obtained by auscultation is more accurate. Mercury column sphygmomanometer Second, why is the use of electronic sphygmomanometers recommended in the Chinese guidelines for the prevention and treatment of hypertension? Although the auscultatory method of blood pressure measurement has been used in clinical practice for more than 100 years, due to the environmental pollution of mercury will be retired from the stage of history (and with it will disappear the mercury column thermometer); in fact, compared to the mercury column sphygmomanometer, the oscillometric method of electronic sphygmomanometer in addition to the convenience of use, reduce environmental pollution, but also has the following advantages: ① alleviate or eliminate the tail number preference: because the tail number of desktop mercury sphygmomanometer can only record even values, and Tail preference is the preference to habitually record blood pressure readings as the last 0 or 5 mm Hg. In clinical practice, the incidence of this tail preference is not low, and directly leads to misdiagnosis or omission of hypertension. The use of an oscillometric electronic sphygmomanometer with automatic transmission can reduce and eliminate tail number preference. ② Simultaneous measurement at multiple sites: Due to inter-arm blood pressure differences, the ankle-arm blood pressure index has value in diagnosing peripheral vascular disease and predicting prognosis. Clinical evaluation of bilateral arm and extremity blood pressure differences is often required. For this reason blood pressure of different extremities should be measured simultaneously to reduce human error and to exclude differences caused by fluctuations in blood pressure at different moments and in different mental states. (iii) In-office self-service blood pressure measurement: In-office self-service blood pressure measurement is relative to manual in-office blood pressure. It is an improved instrument based on the oscillometric electronic sphygmomanometer, in which the doctor initially places the cuff on the patient, directs the blood pressure measurement and measures the blood pressure once, confirms that all conditions are normal and leaves, and then leaves the patient alone in the office, where the instrument automatically measures the blood pressure three more times without medical personnel present, and finally displays the average of the three times. Self-service blood pressure measurement in the consultation room can reduce the occurrence of white coat hypertension and overtreatment. The oscillometric electronic sphygmomanometer with a nighttime start function: An auxiliary start device is added to the oscillometric electronic sphygmomanometer to give it a memory function to achieve a function similar to that of a dynamic sphygmomanometer. Studies have shown that nighttime blood pressure is a better predictor of target organ damage in hypertension than daytime blood pressure, and oscillometric electronic sphygmomanometers can be used in places where other noninvasive blood pressure measurement methods cannot be used (e.g., deep sea, high altitude, etc.). The oscillometric electronic sphygmomanometer is also very effective for patients who cannot be accurately identified by the Koch sound. At present, home blood pressure measurement is considered beneficial to improve the rate of hypertension control, and domestic and international guidelines recommend the use of oscillometric electronic sphygmomanometer to measure home blood pressure. Third, the commonly used electronic sphygmomanometer to measure blood pressure is the basic principle of what? As early as 1876 Marey began to study oscillometric blood pressure measurement method blood pressure, but it was not until 1976 Ramsey invented the use of the oscillometric method to determine the mean arterial pressure instrument. Subsequently, methods for estimating systolic and diastolic blood pressure were found on this basis. With further refinement of the estimation method, the more established oscillometric sphygmomanometer became available in 1991. Unlike the bench-top mercury sphygmomanometer, which determines systolic and diastolic blood pressure by identifying the appearance and disappearance of the Koch’s sound, the oscillometric method of electronic sphygmomanometry is based on the release of the sound. The oscillometric electronic sphygmomanometer senses pulse wave information during deflation or inflation, and obtains systolic and diastolic pressure data through a complex series of conversions and calculations. During deflation, the blood flow in the arm artery goes from completely blocked to gradually returning to normal, and the pulse signal in the brachial artery goes from absent to present, and tends to increase and then decrease. The amplitude of this pulse signal is very weak, but can be sensed and amplified by the pressure transducer of the sphygmomanometer, and an envelope is derived based on the change in cuff pressure and the change in pulse amplitude. Different manufacturers have their own unique systolic and diastolic pressure calculation procedures, with the systolic pressure to peak ratio ranging from 45%-57%, and the diastolic pressure to peak ratio ranging from 74%-82%. Electronic blood pressure monitor Fourth, what are the common types of electronic blood pressure monitor? At present, there are two kinds of blood pressure monitors: “deflating” and “inflating”. The deflating type is to complete blood pressure measurement in the process of cuff deflation; while the inflating type is to complete blood pressure measurement in the process of cuff inflation. The deflating oscillometric sphygmomanometer is the method used by most oscillometric sphygmomanometers today. Its blood pressure measurement process is similar to the mercury column auscultation method, the instrument automatically pre-set the inflation pressure: 160-180mmHg for adults; 120-160mmHg for children; 70-120mmHg for newborns; when the initial pressure is not enough to measure blood pressure, the system will automatically identify and inflate to a higher pressure again. The intelligent oscillometric electronic sphygmomanometer can achieve automatic adjustment of the initial inflation pressure. Once the cuff reaches a satisfactory pressure, the exhaust valve opens and the cuff pressure drops. The venting valve opens in stages and continuously. The inflatable oscillometric electronic sphygmomanometer completes the determination of blood pressure during the process of cuff inflation, and the pressure sensor senses an increasing pressure during the process of inflating the cuff. At this time, the pulse impulse can be detected from the data collected by the pressure sensor. This sphygmomanometer to measure blood pressure in a shorter time, power consumption is small, blood vessels are not compressed, no need to set the pre-inflation pressure. Five, the upper arm and wrist type electronic blood pressure monitor which is more accurate? At present, the upper arm type and wrist type electronic blood pressure monitor mostly use the principle of oscillometric method. However, the Chinese Blood Pressure Measurement Guidelines do not recommend the clinical use of wrist-type electronic sphygmomanometers because their accuracy is not as good as that of the upper-arm type electronic sphygmomanometer. Although the finger artery sphygmomanometer can continuously detect blood pressure per beat, its principle is the arterial volume clamp method, not the oscillometric principle. In general, the finger artery sphygmomanometer can not be used for the diagnosis and detection of hypertension, and is mostly used in scientific research. Upper arm electronic sphygmomanometer Six, how to ensure the accuracy of electronic sphygmomanometer measurement? As the quality of components and system procedures of different oscillometric electronic sphygmomanometers are different, there are some differences in the quality of their products. Only those oscillometric electronic sphygmomanometers that have been verified by international standards can be used in clinical and home use. At present, there are three internationally recognized medical clinical measurement verification programs for electronic sphygmomanometers: (1) the American Medical Devices Federation program; (2) the British Hypertension Society program; and (3) the European Society of Hypertension program. The oscillometric electronic sphygmomanometers certified by international standards can be used in clinical diagnosis and related research. The International Pediatric Association is also interested in oscillometric electronic sphygmomanometers. The quality of commercially available upper-arm sphygmomanometers varies, and whether the products have been verified by the relevant agencies can be inquired online. Seven, what are the precautions when using the electronic blood pressure monitor? The preparation before measurement, body position, sitting posture, cuff specifications and other requirements are the same as the benchtop mercury sphygmomanometer, but the oscillometric electronic sphygmomanometer blood pressure measurement has some special places. Attention should be drawn to. ① Placement of the cuff: The cuff of the oscillometric electronic sphygmomanometer takes into account both the blocking of blood vessels and the signal sensing function. Therefore. Therefore, the appropriate cuff and the proper placement of the cuff is more important. The cuff should not be placed at the elbow joint. Here the cuff does not fit completely in the upper arm and there is a large gap, while the movement of the elbow may lead to errors in blood pressure measurement. In addition, the cuff tube should not be suspended and should be placed securely. ②Limb activity: Body movement and limb activity during measurement can seriously affect the accuracy and repeatability of blood pressure readings because the oscillometric electronic sphygmomanometer relies on very weak cuff pressure changes. Any disturbance can affect the collection of the signal. In addition to active hand movements, passive movements such as vibrations in the ambulance and movement of the hospital bed may also affect the accuracy of the blood pressure readings. (iii) Signal strength: The accuracy of the oscillometric electronic sphygmomanometer in measuring blood pressure is questionable when the pulse is weak, such as in patients in shock, hypovolemia and peripheral vascular disease. In addition, the oscillometric electronic sphygmomanometer encounters challenges in the measurement of blood pressure in newborns, which requires a special design to solve such problems. ④ Environmental noise: Environmental noise such as ambulance movement signals can sometimes be greater than the physiological pulse signal to be detected, resulting in measurement errors. Fortunately, current oscillometric electronic blood pressure monitors have sound insulation settings that can reduce the interference of environmental noise to some extent. ⑤ Heart rate variability: Although the existing oscillometric electronic sphygmomanometers are designed to take into account a certain degree of heart rate variability! However, the more serious heart rate variability can significantly affect the accuracy of the oscillometric electronic sphygmomanometer blood pressure measurements. One of the most obvious examples is atrial fibrillation. Previously, some scholars believe that the oscillometric method of electronic sphygmomanometer does not apply to patients with atrial fibrillation, because the pulse wave of patients with atrial fibrillation is irregular, based on sinus rhythm and determine the systolic and diastolic blood pressure calculation method can not be applied to atrial fibrillation. In fact, the bench-top mercury sphygmomanometer also cannot accurately determine blood pressure in patients with atrial fibrillation. In the author’s opinion, the mean value of the blood pressure readings measured by 3 oscillometric electronic sphygmomanometers in patients with atrial fibrillation can be used as a clinical reference. (6) For patients with diabetes mellitus, renal failure, pre-eclampsia, and peripheral vascular disease, the accuracy of the oscillometric electronic sphygmomanometer may also be affected to some extent due to changes in vascular performance. To further solve such problems, it is necessary to optimize the system program based on the measurement data of a large number of patients to obtain a more reliable calculation method. (7) Some poor quality oscillometric electronic sphygmomanometers have relatively poor accuracy and stability due to the quality of their components and the lack of certification of the system program for bulk data. Blood pressure measurements may be inaccurate when the battery is close to depletion and the voltage is low. For evaluation and calibration of the pressure accuracy of electronic sphygmomanometers, they can be compared to benchtop mercury sphygmomanometers. The pressure detection of the instrument can be considered accurate if the range of pressure difference is <5 mmHg. If the difference is greater than this range, it indicates that the instrument's pressure sensor is functioning abnormally and should be serviced.