Tonometers. Types and characteristics
Earlier, when we touched on the topic of blood pressure, we learned the basic rules, techniques and ways of measuring it. Let’s briefly touch on the topic related to the basic oscillometric method blood pressure measuring with a tonometer, which in turn is mechanical, automatic or semi-automatic.
Mechanical tonometer
The mechanical tonometer consists of a cuff, an air-pumping pear, a stethoscope to listen to the tones and pressure of the blood stream, and a manometer that displays blood pressure data on the display.
The tonometer cuff is fixed in the arm, then an air injection with a pear is performed to completely squeeze the artery. After increasing the pressure by 30–40 millimeters of mercury, air is released, causing the artery to open and the blood stream to resume. Due to the appearance of the first noises in the phonendoscope, we estimate systolic (upper) pressure. Completion of noises shows diastolic (lower) pressure.
Advantages
· Precision. Mechanical tonometers are often used in medical institutions.
· Simplicity. Do not require special care and do not need to recharge or replace batteries.
· Availability. Mechanical tonometers are quite cheap and sold in any pharmacy.
Disadvantages
The main drawback is the complexity of measurement. Often, at home, it is difficult to understand the principle of the device. It is necessary to hear clearly the disappearance and the appearance of blood-stream tones with a stethoscope to determine the upper and lower pressure. Yes! measuring pressure this way will not always work. For people with hearing or vision problems, this method will not be available. And to pump air with the help of a pear, you need to compress it enough, which requires some physical effort.
Automatic tonometer
When an automatic (electronic) tonometer is used, air fluctuations within the cuff are recorded due to the influence of blood flow on the painted area of the artery, so the tonometer converts air fluctuations into electrical signals, which are analyzed and translated into numbers. The advantage of this tonometer is the determination of heart rate and arrhythmia, and the tonometer itself consists only of a cuff and an electronic block.
Separately, it is worth highlighting wrist tonometers, which are comfortable to wear and carry, allowing you to constantly monitor your blood pressure.
Advantages
· Ease of use. To perform the measurement, you must put on the bracelet and press the instrument button.
· Diversity. A large selection of models on the market for different budgets.
· Display. Clear and large display of indicators, which is suitable for people with poor vision.
· Portability. There are compact models, for example, a wrist tonometer. These models are comfortable to wear; they are suitable for people who lead an active lifestyle or with large hands.
· It has measured blood pressure and heart rate memory function, which is suitable for BP monitoring.
Disadvantages
The main problem: The high cost and the need for frequent recharge or batteries, possible errors in the measurement, but within the allowed values when used correctly.
Semi-automatic tonometer
There are also semi-automatic tonometers, air in the cuff in which the pear is pumped, and reception of pulse and blood pressure indicators is displayed on the screen and performed without the use of a stethoscope.
Precision of measurement of tonometers
The most important criterion for the correct functioning of the tonometer is precision. Whether the instrument is automatic or mechanical, all instruments can give an error within ±10 mmHg. in blood pressure level and ±5 in pulse data. Only when an inexperienced user uses the device, the error may be greater.
The automatic tonometer has an error of ±10 mmHg., but if you follow the blood pressure measurement rules, the BP numbers will be as correct as possible. At home, these devices are quite convenient, it is only necessary to operate them correctly.
Blood pressure measurements may also change due to different interferences created by movements of the hands, whole body, or conversations during the measurement.
It is important to understand that the dispersion in the readings will be presented in any case if two or more measurements are made in a row. Therefore, between measurements it is necessary to take a break of 2–3 minutes, measure 2–3 times and calculate the average of these three indicators.
It is necessary to measure the pressure on both the left and right hand. Between measurements, the cuff should be loosened so that it does not press the hand. This gives the blood vessels restored elasticity. It is also necessary to correctly apply the cuff: compressed, but not tight and not loose, so that 2 fingers pass between the surface of the hand and the cuff. The cuff position should be the same in all dimensions.
How to choose a tonometer?
The choice of the tonometer for each person is absolutely individual and depends on the financial possibilities, the preferences of the measuring method and the frequency of use of the instrument. It also takes into account the age and presence of cardiovascular diseases in a person. Consider the basic criteria to consider when choosing a tonometer.
· If used frequently, choose an automatic or semi-automatic device. The most convenient in this case will be the memory function.
· For the use of young people absolutely serves any mechanical or automatic tonometer, and in the case of middle-aged people you can use tonometers on the shoulder and on the wrist. But for the older patient, it is better to choose an automatic brachial tonometer, to minimize the measurement error due to age-related change in the vessel walls and reduce their elasticity.
· Depending on the elbow size, you can also vary the cuff size, make sure you use the right cuff for you. There are three main sizes: small (18–22 cm), medium (22–32 cm), large (32–45 cm).
· In the presence of arrhythmia, you should prefer a tonometer with the function of determining the pulse and the presence of arrhythmia at the time of measurement.
· Measuring blood pressure with a mechanical device has certain difficulties and is more suitable for use by doctors, nurses or people who know how to use it correctly.
Take care of your health and monitor your blood pressure indicators. This will help you respond to any malfunctions in your body in time and help you.
It should be remembered that if the blood pressure is above 140/90 mmHg. requires consulting a doctor for an examination and, if necessary, prescribing treatment.
