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Measurement Results & Accuracy




My doctor says that digital machines are not accurate and that only a doctor or an experienced nurse can take a blood pressure seriously. How accurate is the result of a Microlife digital blood pressure monitor?

  • Microlife's digital blood pressure monitors perform the measurements by applying the so called 'oscillometric method'. This method has been well accepted worldwide for more than 30 years and is applied in hospitals every day, whenever the patient's blood pressure needs intensive and highly accurate control. Thereby, the blood pressure is accurately detected by analysing the pressure oscillations that can be measured during the deflation period of the cuff pressure.
  • Microlife has many years of experience in analysing these body signals and detecting the blood pressure very accurately. The high accuracy of Microlife`s detection principle is confirmed by comprehensive clinical studies which are performed by independent medical centres on highest international standards.
  • Please note that high «accuracy» is specifically given by the fact that the electronic device enables you to perform measurements at home under relaxed conditions. In combination with Microlife's accurate blood pressure monitor, this possibility is by far the best condition for an accurate determination of the human blood pressure!
  • Most doctors and nurses of course prefer the stethoscope method because they can listen to the signals and get a deeper impression of the patient's condition. In comparison, the electronic devices cover a lot of uncertainties for doctors where they cannot follow how the result is detected.
  • The doctor's method of obtaining the pressure covers many personal influences and also may not give the person's "real" pressure as the patient is not as relaxed as at home.
  • It is a proven medical fact that a slow deflation rate of 2-3 mmHg per second is essential to obtain accurate results with the doctor's measurement. But often, doctors or nurses use a much higher deflation rate and obtain wrong results.
  • The most convincing fact is that the world's leading experts on blood pressure monitoring prefer frequent home measurements by electronic devices against periodic measurements taken in their office!
  • With electronic monitors people perform many measurements because it is a very easy and attractive to measure ones blood pressure. It is quite normal for the measurement results not to be identical to each other. If a doctor were to measure the pressure three or four times (which is never done!) he would also get different values.




I expect to get the same results every time with the Microlife monitor, but I always get different results. Is the device defective?

  • The human blood pressure is not a constant body parameter. For normal physiological reasons, your blood pressure may fluctuate by up to 30 mmHg within a short time-period. So the blood pressure may change between the measurements. It is actually not easy to have same conditions during sequentially performed measurements. It is not unusual that sequential measurements give different readings based on the unstable physiological conditions and influencing side factors (talking, noise, movements, etc.).
  • Therefore the average of several results, obtained on several days, under comparable living situations, during the same time-frame of the day represents your individual blood pressure. Measure, for example, an hour after you had dinner on three sequential days and you will not find significant differences. The average of these results best represents your blood pressure.




My doctor says that my blood pressure is 150 to 100, but why does the Microlife device give results around 135 to 95?

  • You might be not as relaxed at the doctor's as you are at home. When you are nervous at the doctor's, the blood pressure is higher. A lower systolic pressure by 15 mmHg is normal in a relaxed surrounding.
  • Human blood pressure varies over the day. Changes up to 30 mmHg within a short time period may appear in relation to physical activity (sport, brain, stress, stomach, etc.).
  • We recommend that you measure your blood pressure at the same time frame of day and under comparable conditions, eg. every evening about an hour after you had dinner.
  • Each manufacturer applies his own principles in detecting blood pressure. A difference between device and doctor measurement can be based on different 'skills' and can be compared with, when two doctors measure the same patient with their stethoscopes, but obtain different values.




I understand that blood pressure varies over the day and I get different results accordingly. But how high is my blood pressure really, then?

  • The average of several results, obtained on several days, under comparable living situations and during the same time frame of the day represents your individual blood pressure.
  • Measure, for example, an hour after you had dinner on three sequential days and you will not find significant differences. The average of these results represents your blood pressure.




Before I bought a Microlife blood pressure monitor, I used a device from another company. Why do I get different results with the Microlife device?

  • Most digital monitors work on the so called 'oscillometric method'. Each manufacturer applies his own principles in analysing the measured signals and finding the related systolic and diastolic values. Significant accuracy differences between the monitors are shown by several clinical studies.
  • Microlife has many years of experience in analysing body signals and detecting the blood pressure very accurately. The high accuracy of Microlife`s detection principle is confirmed by comprehensive clinical studies which are performed by independent medical centres of the highest international standards.
  • Each manufacturer applies his own principles that are also optimised for the 'standard' population. There might be individuals for whom one device is more suitable than another. In the same way, two doctors who have different skills in measuring blood pressure with their stethoscopes can get different results.
  • A reason for different data might be that the blood pressure may change between the measurements. It is actually not easy to have same conditions at sequentially performed measurements. It is not unusual that sequential measurements taken with the same device give different readings based on the unstable physiological conditions and influencing side factors (talking, noise, movements, etc.)!
  • If you want to compare two systems, you have to eliminate as many influencing factors as possible. The measurements have to be performed without any outside disturbance and by following the instructions as given in the manual. Each measurement should be performed under comparable living conditions at the same time frame of the day. Take care to relax between the measurements and wait for at least three minutes. Perform several measurements with each device and compare the average values. Only after following the above instructions accurately will you know how big the differences really are.




How do I know if the device is still accurate after long usage or after being dropped?

  • Monitors still give accurate results, if the device has been dropped, but you cannot detect any malfunction when operating it. The main component that mainly influences the accuracy is stored in the computer program. This software either works or doesn't. Other parts do also affect the accuracy, eg. deflation valve or the pressure sensor are very well protected against modifications by accidents or ageing.
  • In any case and in accordance with international standards we recommend that you ask your authorized Microlife dealer to perform an accuracy check every two years.




Why and when should I send the device in for an accuracy check?

  • Microlife's blood pressure monitors are developed to remain accurate for a long product life. To guarantee this accuracy we recommend - in accordance with international standards - that you ask your authorized Microlife dealer to perform an accuracy check every two years.




Which monitor is most accurate, a wrist or an upper arm model?

  • Both devices have a comparable accuracy. However, as each human has individual blood vessel and tissue constitution, one of the two different positions may have advantages for some individuals.
  • It is possible that the signals of some individuals are very weak at the wrist due to their artery wall constitution. These people may get frequent error messages.
  • Measurements at wrist are more sensitive against movements during measurement, which may result in a higher number of 'error' messages. So please do not move the wrist or hand during measurement!
  • It is very important that the cuff is positioned at heart level during measurement. This is more difficult at the wrist and may lead to wrong results. 10 cm higher than heart means an under estimation by 8 mmHg while 10 cm below heard level means that the results will be 8 mmHg to high!
  • Wrist devices are very simple and faster to use than upper arm, so normally wrist devices lead to more measurements. As the blood pressure has high variations over the day, it is important to obtain as much data as possible. Therefore, wrist devices enable a good control of the blood pressure profile.
  • Arteries at the wrist are positioned very near to the surface, so the body signals are less covered by tissue than at the upper arm, this may lead to better readings at wrist than upper arm.
  • People with obese arms may face problems with upper arm cuffs, but get better results at the wrist.




I have a Microlife upper arm and a Microlife wrist monitor. Why do I get different results?

  • Both devices have a comparable accuracy and follow the same principle. However, as each human has individual blood vessel and tissue constitution, one of the two different positions may have advantages for some individuals.
  • It is very important that the cuff be positioned at heart level during measurement. This is more difficult at the wrist and may lead to wrong results. 10 cm higher than heart means an under estimation by 8 mmHg while 10 cm below heard level means that the reading will be 8 mmHg too high!
  • It is possible that the signals of some individuals are very weak at the wrist due to their artery wall constitution. These people may get frequent error messages.
  • Arteries at the wrist are positioned very near to the surface, so the body signals are less covered by tissue than at the upper arm, this may lead to better readings at wrist than upper arm.
  • People with obese arms may face problems with upper arm cuffs, but get better results at the wrist.
  • Measurements at wrist are more sensitive against movements during measurement, which may result in higher number of 'error' messages. So please do not move the wrist or hand during measurement!
  • As individual factors affect the reading, we recommend that you compare both devices and choose the one that gives the most constant results. If you get significantly different values, we recommend that you use the upper arm model (upper arm blood pressure measurement is more established at this state).




Is a manual monitor as accurate as an automatic device?

  • Both systems supply the same accuracy. Automatic models have an installed electric pump instead of the hand-pumping ball but this has no influence on the accuracy.




The systolic pressure measured by the Microlife blood pressure monitor is similar to what my doctor measures, but why is the diastolic pressure about 10 mmHg higher with the digital monitor?

  • The diastolic pressure is very difficult to detect with the stethoscope and depends very much on the observer's capabilities. The correlation of the diastolic pressure is more difficult than the systolic.




I measure at home several times sequentially with a Microlife blood pressure monitor. The first results are fine, but why are they becoming very low with approx. the 5th measurement?

  • The reason might be blood congestion, because you are not waiting long enough between measurements or are not releasing the cuff between measurements.




Do Microlife blood pressure monitors also perform reliable measurements during pregnancy?

  • Yes, Microlife monitors are specifically validated for pregnancy and pre-eclampsia. During pregnancy the pressure should very frequently be controlled to prevent a critical phenomenon, which is called preeclampcia. About 20% of women develop high blood pressure during pregnancy. Please contact your doctor immediately, if you recognize a significant increase of your blood pressure readings during pregnancy!