How to choose a tonometer
Types of tonometers
Blood pressure measuring devices are divided into three types:
1. Mechanical (manual). The oldest and most common device, consisting of a cuff for putting on the shoulder, a pear for pumping air and, directly, a pressure gauge. For a complete set, a phonendoscope is required, with which the heart rate is listened to.
Advantages — low cost and measurement accuracy. They do not require battery power and they rarely break down.
The disadvantages are in a certain complexity of the process. If you don't have the skills, you can get a large error in the readings. In addition, the mechanical device does not measure the pulse, it has to be done manually by placing your fingers on your wrist and counting the beats. Sometimes manual tonometers themselves can sin with incorrect readings, so it is recommended to periodically give them to a specialist for verification.
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| Mechanical tonometer. |
2. Automatic blood pressure monitor. It consists of a cuff on the shoulder or wrist and a metre with a display and a built-in electronic sensor and a compressor that pumps air into the cuff. Such a model is more expensive than a manual one, but it is easier to handle and does not require special skills. It is enough to apply a cuff, press the button, and the device will do everything by itself. The disadvantage is the need for power (batteries or mains), which will have to be constantly taken care of. Doctors also do not favor automatic machines, considering them a purely home-based diagnostic option. Although expensive models are quite accurate in their readings, but, like any electronics, they can malfunction.
3. Semi-automatic. The device has an electronic sensor and display, as well as an automatic tonometer, but the cuff is inflated not automatically, but manually, with the help of a pear. The device has an average price compared to the two above-mentioned models. Of the advantages, it is worth noting the reduced power consumption, diagnostic functionality similar to an automatic tonometer, and of the minuses — except that manual pumping.
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| Semi-automatic tonometer. |
4. Smart tonometer. The pressure metre can be part of the functionality of a smartwatch or a fitness tracker, but in this version it has not quite caught on, as it is a secondary function in gadgets. Portable smart tonometers are a transitional link from traditional automatic metres to smartwatches with the function of blood pressure monitoring. They also have a cuff and a measuring unit with a display, and the main difference is PC compatibility. This allows using special software to analyze readings, put them into graphs, keep statistics, transmit to a smartphone via Wi-Fi or Bluetooth, and even perform voicing measurements. And a smart tonometer can replace a barometer and thermometer, recording the temperature and pressure of the environment. The disadvantage of a smart device is only its high price.
When choosing a tonometer, preference should be given to a device that you can use without assistance. For example, you should not buy a hand-held device if you do not have enough strength to inflate the cuff, and a smart one if you do not plan or cannot use its full functionality.
Functions and capabilities of tonometers
Each tonometer makes measurements in its own way. Let's consider the possibilities of all kinds in order.
Manual tonometer
A mechanical device requires some effort to obtain blood pressure data. It is necessary to put a cuff on the shoulder and pump air into it with a pear to an indicator on the pressure gauge exceeding the usual upper (systolic) pressure of the patient by 20-30 points. Then gently release the valve. The air will start coming out of the cuff, the pressure on the blood vessel will decrease, which will make it possible to hear the pulsation of the artery using a phonendoscope, and the digital value will be fixed on the dial of the pressure gauge. The beginning of the pulsation will show systolic pressure, and the end — diastolic (lower).
The mechanical tonometer does not perform any other functions other than determining the pressure. When buying, you should pay attention to the quality of the phonendoscope, connecting tubes. The accuracy of the readings directly depends on them.
Automatic and semi-automatic tonometer
Automatic and semi-automatic tonometers have a number of common properties:
- absence of pressure gauge and phonendoscope;
- formation of readings using an electronic sensor with subsequent output to the display;
- operation from batteries and (or) mains.
The measurement of pressure in the circulatory system of electronic devices is carried out by means of a microprocessor that recognizes not the pulsation of blood, but the fluctuations of the air in the cuff, and performs analysis and calculations using special algorithms.
In addition to measuring blood pressure, tonometers of both types perform other functions, for example:
- pulse measurement. Shows the number of heartbeats per minute;
- calculation of the average pressure. Output based on the results of the last three measurements;
- storing measurement results in memory (from 30 to 200 readings indicating the date and time of measurement);
- definition of arrhythmia. If the patient has an erratic pulse, this will be indicated by an indicator on the display in the form of a heart.
Smart Tonometer
A smartwatch or fitness tracker equipped with a pressure measurement function, depending on the model, may have other activity and health monitoring capabilities, including:
- pulse measurement;
- counting steps, calories;
- recording of an electrocardiogram (ECG).
When choosing a smart device for blood pressure monitoring, it is important to determine what the main goal is being pursued. If pressure and pulse monitoring is a secondary task, and the functions of a watch /fitness tracker are more needed, it is worth choosing them. If you need constant monitoring of blood pressure with accurate readings, it is better not to combine several devices in one and purposefully buy a smart tonometer, such as Xiaomi iHealth 2 .
The reliability of the algorithm for measuring blood pressure in smart gadgets has not yet been fully studied. Although many predict a great future for them, and the development of smart technologies does not give reason to doubt this.
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| Fitness tracker with a blood pressure monitor. |
Types and sizes of cuffs
The cuffs are worn on the shoulder or wrist. The first option is divided into three main types, depending on the circumference of the patient's arm:
- children's (from 15 to 22 cm);
- standard (22 – 32 cm);
- universal (22 – 42 cm).
That is, we measure the circumference of the shoulder and look at what numbers we get into. In fact, the universal cuff is the most common and is suitable for almost all adults, regardless of their complexion.
There are cuffs and longer lengths, but not all manufacturers. Wide gradation in size is offered only by leading brands, for example, Omron or Microlife.
With a cuff on the wrist, things are much easier. It is important to focus only on your own comfort and take into account age. A wrist tonometer will be more accurate for people under 50. This is due to the fact that the artery in the wrist is thinner than in the shoulder, and over the years it becomes even weaker, so the data in the elderly with such a device can be read incorrectly.
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| A blood pressure monitor on the wrist. |
Types of tonometer power supply
Mechanical metres do not require power, they work only from the muscular strength of a person. Smart devices are equipped with Li-ion batteries of different capacities, but in general the charge lasts for several days, and in some cases months.
Automatic and semi-automatic tonometers operate from different power sources:
Batteries. The elements can be of type AA or AAA (finger or micro-finger). They serve from 1 month to a year, depending on the quality of the batteries and the device itself. The fact that the charge is coming to an end can be notified by the battery charge indication, as on a mobile phone.
The battery-powered tonometer is advantageous for its battery life, because you can take it with you on the road, take measurements in any convenient place without being tied to an outlet.
Network/batteries. The devices are equipped with an adapter to the mains with a voltage of 230 V, but they also have a slot for batteries. The advantages of a tonometer with two types of power are obvious:
- saving battery power, less need to buy;
- the user has no restrictions in movement;
- the tonometer will still work, even if the batteries are dead, and there are no new ones at hand.
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| A blood pressure monitor with batteries and an adapter for the network. |
Battery. Tonometers with a battery are mobile, convenient, work for a long time, and charging from the network takes only a few hours. The main disadvantage of such devices is their fragility. The average battery life is 2 years, after which most tonometers are subject to disposal, since structurally it does not involve battery replacement.
As you can see, the medical equipment market is replete with offers of tonometers for every taste and purse. It is important not to get lost and buy the device that is most suitable for your body and that you can use without assistance. We hope our article helped you in this.
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