Mean arterial pressure (MAP) is the pressure in the bloodstream during the entire cardiac cycle, regardless of systole and diastole. This indicator reflects the blood supply to vital organs. In order to find out which AAD you have, you need to arm yourself with a tonometer, paper and a pen. Below we provide the formulas by which this indicator is calculated.
Blood pressure measurement methods
Blood pressure is one of the main parameters of the system. It, unlike atmospheric, is measured in millimeters of a mercury table, and not in pascals.
There are two indicators of blood pressure:
- Systolic blood pressure (SBP) - the level of blood pressure at the time of maximum contraction of the heart. It is created by the left ventricular stroke volume, ejection rate, elasticity and aortic diameter. Normal indicators are 100-139 mm Hg.
- Diastolic BP (DBP) - displays the pressure at the moment of greatest relaxation. DBP depends on the duration of diastole and OPSS - total peripheral vascular resistance. The DBP value is 60-89 mm Hg.
The invasive (direct) method of measuring blood pressure is applicable exclusively in a hospital setting, for example, during operations and in the intensive care unit. For continuous monitoring, a catheter with a sensor is inserted into the radial artery (on the wrist), and the data is displayed on a monitor. Despite the indisputable help in conditions when a person is in serious condition, thrombosis, bleeding and infection of the puncture site may occur.
Among doctors and ordinary users, non-invasive devices and methods are widespread that allow quickly, without causing discomfort and bloodlessly determining the degree of patient's blood pressure.
| Palpation method | It consists in the gradual clamping and relaxation of the limb with the cuff in the area of the artery, and its probing below the place of compression. SBP is determined by the pressure on the manometer at which pulsation begins, diastolic - at the moment when it disappears. |
| Auscultatory method | Invented in 1905 by N.S. Korotkov, and has not changed since then. The measurement requires a sphygmomanometer and a phonendoscope. The principle of the method is identical to palpation, only the appearance or disappearance of the pulse is heard. |
| Oscillometric method | The device of electronic tonometers is based on this technique. It can be used to measure pressure at any point in the artery, including the wrist, and without the participation of a second person, which makes portable mini devices popular. With a gradual decrease in pressure in the cuff, oscillations (oscillations) appear in it, which correspond to the pulsation of the vessel under it. They appear when the air pressure drops to the SBP level, and disappear when it is compared with the DBP. |
In everyday practice, the most accurate and convenient is the auscultatory method according to the Korotkov method. Mechanical phonendoscopes are not expensive and are in almost every family, which allows you to control the pressure for yourself and your loved ones.
The advantages of the technique are resistance to rhythm disturbances and hand movements during the study. However, this technique is sensitive to ambient noise and the need to accurately position the phonendoscope membrane over the artery. Since the method requires human participation, the measurement error can range from 7 to 15 mm Hg.
Modern cuffs are available in different sizes to measure blood pressure for both a newborn and a very fat person.
Calculation formulas
Modern methods for calculating average blood pressure:
- AVG = DBP + (SBP - DBP) / 3
- SAD = 2/3 (DBP) + SAD / 3
- SAD = [(2xDAD) + SAD] / 3
where MAP is mean arterial pressure
DBP - diastolic blood pressure
SBP - systolic blood pressure
There is a fourth formula that uses pulse BP (PAP), which is obtained by subtracting DBP from SBP. It reflects the strength that the heart generates with each contraction.
- Avg = DBP + PAD / 3
You can determine the ideal blood pressure for different age categories using the following technique:
The formula for calculating blood pressure by age:
- SBP = 109 + (0.5 × age) + (0.1 × weight);
- DBP = 63 + (0.1 × age) + (0.15 × weight).
At the moment, these calculations are not relevant because the World Health Organization and the American Heart Association have approved blood pressure guidelines for people aged 12 years and older.
Convenient tables have been developed for babies that take into account age, gender, and SBP and DBP values.
What are the calculations used for and what is their diagnostic value?
Such a number of formulas derived by scientists suggests that mean blood pressure is of great importance in clinical practice. Despite the fact that at the moment many online calculators and mobile applications have been developed that calculate its value, manual calculation is still popular and brings its undeniable benefits. Every doctor knows how to calculate blood pressure.
Normal values of mean arterial pressure are from 70 to 110 mm Hg.
Higher numbers are an indicator that the heart is working harder than it should. A large ARP is observed with heart failure, myocardial infarction.
A low AVR can be fatal if not corrected in any way. With numbers below 60 mm Hg. organs do not receive the required volume of blood, a state of shock develops. MAP falls with sepsis, blood loss, stroke, and polytrauma.
Conclusions
Mean arterial pressure is an important indicator of the state of hemodynamics. Its calculation is most often performed by the attending physician during examination in order to determine how well the internal organs are supplied with blood.
If you, having decided to calculate the pressure according to the indicated formulas, find deviations from the norm, do not hesitate to contact a general practitioner or cardiologist for advice. The same should be done if you have identified hypertension.
