“Why do batteries in my blood pressure monitor discharge quickly? What batteries should be used in these devices? When and how often should batteries be replaced?”
Only LR type alkaline energy-intense batteries should be used in electronic blood pressure monitors. Only when using LR type alkaline batteries, the manufacturer guarantees uninterrupted operation of the device for 200-400 cycles of measurement, i. e. when measurement is taken 2-3 times a day, batteries will last for 4-6 months. It is not recommended to use R type batteries since the capacity of such batteries is not designed for long-term use in blood pressure monitors, and therefore, due to rapid discharge of batteries it seems that the device is faulty. LR type batteries of any manufacturer can be used.
Batteries should be changed when the corresponding symbol specifying low capacity is displayed on the blood pressure monitor screen. Do not take this symbol into account as a sign of low battery when it appears on the screen simultaneously with other symbols at the time of switching on the device. At this moment the blood pressure monitor display is being tested, and the presence of this symbol indicates only the operating capacity of the display.
“Do I need a network adapter? What types of network adapters can I use? Do I need to remove batteries when using an adapter?”
The automatic upper arm blood pressure monitors have a socket for connecting a network adapter. An adapter can be useful if the blood pressure monitor is used at home. If you take along the blood pressure monitor (for example, to work, summerhouse, to the country), it is more convenient to use batteries for mobility. When using an adapter, it is not necessary to remove the batteries out of the device since they are automatically switched off when an adapter plug is connected to the blood pressure monitor. Carpal blood pressure monitors are not designed to have an adapter socket. Do not use adapters that are not recommended by the manufacturer since adapters are subject to certain requirements for specifications (in particular, electrical safety), which are not met by a significant part of adapters sold on the market. Using an adapter that is not recommended by the manufacturer of the blood pressure monitor voids the device warranty!
Can I use accumulators of the same size instead of batteries?
Accumulators can be used, though it is not very effective. The case is that voltage specified in the accumulator certificate is 1.2 V. The blood pressure monitor requires 4 accumulators, i. e. the total voltage will make up 4.8 V, but 6.0 V is needed. Therefore, being fully charged, accumulators will not provide a voltage sufficient for a long-term operation of the device, so accumulators will last for not more than two weeks until the next recharge. After that, not fully discharged accumulators will have to be recharged again, which will negatively affect their shelf life (when it comes to nickel-cadmium accumulators). Let’s calculate: four sets of alkaline batteries will be enough for about a year and a half or two years. Accumulators can last for the same period, but they will have to be charged every two weeks. Therefore, alkaline batteries are preferable from the perspective of cost and usability.
Why do the results of arterial pressure measurements with a manual blood pressure monitor differ from the readings obtained with an oscillometric device? Why are the readings obtained during successive arterial pressure measurements by an oscillometric method different each time? And readings obtained during successive measurements with a manual blood pressure monitor are the same? What is then the true value of arterial pressure?
Today, the “gold standard” of arterial pressure measurement is considered to be N. S. Korotkoff sounds method which is recognized by the World Health Organization. However, we should remember that this is an indirect method of arterial pressure measuring. Arterial pressure is certainly measured with some error, which is determined by the elasticity of arterial walls and soft tissues, amplitude and shape of a pulse wave and other factors, which are individual for each person. If to refuse rounding and use the exact scale interval of the manometer, the difference between the neighboring readings will be seen as well when using a manual blood pressure monitor. Numerous experiments comparing measurement by Korotkoff method with the direct (reference) invasive method (with the introduction of the sensor directly into the artery) showed that an error, when using Korotkoff method, is usually within ±5-7 mm Hg. Readings of the manometer taken aurally also contain some error which depends on the individual characteristics of a person (speed of reaction, skills, etc.). As a result, accuracy of manual blood pressure monitors consists of three components: the method itself, accuracy of the manometer and the error of determination of the moment of reading. In fact, the error value can be up to 15 mm Hg! Results of measurements are also influenced by the rate of air injection into the cuff, rate of air drain and the amount of pressure built up in the cuff. If to consider natural fluctuations in arterial pressure, the difference between the two neighboring measurement readings can be even greater.
If a person measures his arterial pressure by himself with a manual blood pressure monitor, as a rule, he “adjusts” the results of repeated measurement to the first one due to a large error. There is a widespread misconception that human arterial pressure cannot change much between two consecutive measurements. It should be known that arterial pressure is not constant. It rhythmically pulsates in tune with a heartbeat, and varies significantly even in healthy people over short periods of time. When change in “upper” (systolic) and in “lower” (diastolic) arterial pressure, fluctuations in arterial pressure in healthy people make up to 30 mm Hg and up to 10 mm Hg, correspondingly!
When self-measurement of arterial pressure with a manual blood pressure monitor, readings turn out to be often overestimated due to the difficulties associated with a measurement process itself (manual pumping, adjustment of the air relief valve, intense attention when listening to Korotkoff sounds and looking at the manometer readings). In some people, blood pressure may change because of the excitement associated with the procedure of its measurement. Arterial pressure readings are greatly influenced by human emotions. When arterial pressure measurement is taken by the doctor, readings are usually higher than in a calm home environment. So, it is impossible to conclude about the accuracy of the blood pressure monitor relying on the obtained difference in readings. This is explained by emotional tension of a person, i. e. in such cases the so-called white coat effect is manifested. Practice shows that about 20% of people are being treated for hypertension, not having it at all due to this! That is why it is important to take arterial pressure measurement in a more relaxing atmosphere at home, and not on a case-by-case basis only when you are at the doctor’s office, although it is very important to know your arterial pressure also in “critical” situations.
Oscillometric semi-automatic and automatic devices for measuring arterial pressure are designed to exclude the human factor from measurement readings, thereby increasing their reliability.
To obtain reliable and comparable readings, blood pressure should be measured at about the same time of a day as far as possible, and preferably in a calm optimistic mood. In this case, all the readings are true (for a given period of time).
Why is a 3-5 minute interval between measurements needed?
This interval is individual for each person and, as a rule, the older the person, the more necessary an interval between measurements. This is due to the reaction of arterial walls when they are compressed by the cuff of a blood pressure monitor. If you take a second measurement immediately, arterial pressure readings may be distorted: they are usually lower due to the fact that blood circulation has not recovered yet. Blood pressure should not be unnecessary measured without a special need several times a day since artery compression is still an additional tension on vessels.
“The cuff is swollen too much, at the same time my arm becomes numb” ... “How to put the cuff on to get the correct measurement readings?
In order to measure arterial pressure accurately, the cuff should be put on correctly: wrap the cuff around the arm so that the edge of the cuff is 2-3 cm above the elbow bend. Make sure that there is no space between the cuff and the arm. To eliminate this space, put on the cuff with a little cone. Make sure the cuff fits closely to your arm and has a good contact with your skin.
If you put the cuff loosely, then when pressure is inflated, the cuff inflates, filling the left gap between the arm and the cuff, and only afterwards begins to build up the required pressure on the arm. At that, power consumption is increased (in case of an automatic blood pressure monitor) since the compressor operating time is increased. In case of a semi-automatic blood pressure monitor, one will have to pump the bulb more, which will also take more time. In this case, the arm is under high pressure for a longer time, it becomes numb, and measurement readings are distorted. Due to excessive swelling, the cuff may lose its tightness.
How can one check the oscillometric device that measures arterial pressure on the upper arm for the accuracy of readings at home?
If you have two oscillometric blood pressure monitors, you can connect them together to one cuff so that they measure your arterial pressure at the same time. This is applicable for two semi-automatic models with one charger and air relief valve or for automatic and semi-automatic blood pressure monitors. It is not allowed to check two automatic blood pressure monitors by such a method!
During such a check the numeric difference in readings between two devices shall not exceed the total instrumental error of the devices (not more than 6 scale units). A good experiment can be carried out if to combine two methods of arterial pressure measurement – oscillometric and auscultatory (at that, one can use only devices for arterial pressure measurement on the upper arm). When using two methods of arterial pressure measurement (oscillometric and auscultatory) at the same time, a person measures arterial pressure by Korotkoff sounds method by hearing, and the oscillometric device displays the readings of arterial pressure measurement on the display. No matter how many times this experiment is repeated, in the vast majority of cases measurement readings obtained within one period of time fit within the error limits of both methods with a small difference. Moreover, the results obtained on both devices will fluctuate equally through time. It should be borne in mind that sometimes (very rarely) there may be situations when two different (auscultatory and oscillometric) methods give different results even when used simultaneously. This is possible due to advanced atherosclerosis and reduced arterial elasticity, severe arrhythmia, weak pulse wave and other serious diseases. In this case, it may turn out that none of the above methods provides the correct readings of arterial pressure measurement. In such cases, it is necessary to seek qualified help from a cardiologist.
Why are blood pressure monitors measuring arterial pressure at the wrist not suitable for some people?
It should be borne in mind that readings of arterial pressure measured on the wrist in some people may differ from readings of arterial pressure measured on the brachial artery. This is due to a large distance of the arteries of the wrist from the heart. In addition, with age, such a disease as atherosclerosis develops, which also affects arterial pressure readings measured on the wrist. The undeniable advantage of wrist blood pressure monitors is that they are portable, compact and easy to use. Knowing individual characteristics of your organism, in some cases you can take into account the difference in arterial pressure measured on the wrist and on the brachial artery. The device designed for the wrist measures arterial pressure accurately only on the wrist. Therefore, prior to buying a device for measuring blood pressure on the wrist, it is better to consult your doctor. The undeniable advantage of wrist blood pressure monitors is that they are compact and easy to use (especially during trips, in the country, in the office).
Why is it necessary to keep devices for the wrist strictly at the level of the heart when measuring?
When measuring arterial pressure with any blood pressure monitor, it is necessary to hold the cuff at the same level with your heart! In addition, the necessary condition for correct arterial pressure measurement on the wrist is that the blood pressure monitor should be at the same level with your heart. What is the reason? When raising the arm, blood pressure decreases in it, and when lowering it, blood pressure increases. If you hold your arm at different levels relative to the heart, you will receive different arterial pressure readings. As a rule, the condition of the correct position of the arm relative to the level of the heart is not fulfilled by people, which leads to incorrect measurement readings. To ensure your arm to be at the same level all the time, it is advisable to lean it against the chest, touching one and the same point on the shoulder with your index finger. In this case, the device will be at the same level with your heart.
Why does the arrow in the manometer of a manual blood pressure monitor not stand still when the “tap” on the bulb is fully closed?
During pumping the cuff, air enters through the hole in the bulb, sucking in small particles of dust that are in the air. Over time, the rubber check valve, which is located in the bulb, becomes clogged and pressure in the cuff begins to drain through it, which leads to the above problem. In this case, it becomes more difficult to perform pumping movement. The pressure built up in the bulb due to the clogged rubber valve becomes excessive, which can cause the bulb to “slip off” the “tap”. It is necessary to clean the rubber valve in the bulb as needed. To do this, it is necessary to separate the rubber part of the bulb from the valve. To protect the bulb against the trouble of the valve clogging, you can keep it suspended when pumping, without laying it on the table or your knees. This will prevent small dust particles from entering the valve. Pumping should be performed with smooth movements of the hand, by squeezing the bulb completely flat, then relaxing the hand ensuring bulb fully inflates before repeating procedure.
Why is the arrow in the manometer at zero pressure in the cuff not strictly in the center? Is it defect?
The manometer arrow shall be within the zero area and shall be set by the manufacturer when the blood pressure monitor is adjusted to the required position to ensure the required accuracy. If at zero pressure the arrow is out of the specified area, contact the service center for checking.