Identification > Measurements > Methods of measurement > Measurement of blood pressure

In practice of clinical and physiological researches have developed and methods of measurement of arterial, venous and capillary pressure in a system circle, in vessels of a pulmonary circle, in vessels of separate organs and skew field parts are widely used. Are exists direct and indirect methods of this measurement.

Direct measurement of blood pressure. The measurement is carried out directly in the vessel or cavity of the heart, which enters the catheter, transmitting to an external pressure measurement device or sensor to sensor inputs at the end. Ultimately, the measured signal is fed to the ADC channel and further into the computer. The basic measured quantity is the instantaneous pressure in the vessel or cavity of the heart. Secondary measured value is the average, minimum and maximum pressure and other indicators, which are determined by recording devices. Direct measurement of blood pressure can be achieved in almost any areas of cardio-vascular system. Measurement of pressure in the cavities of the heart and central vessels could only direct method.

The main advantages of this method is its accuracy and informativeness. Curves of pressure over time. Obtained by this method are a valuable source of physiological information, and is best suited for use in the identification of parameters of the circulatory system.

Arterial pressure curve. One cardiac cycle.

The main disadvantage of direct measurement is the need to introduce in the bloodstream of a measuring device. Direct measurements of blood pressure are actually surgery and is performed only in a hospital environment.

Indirect measurement of blood pressure. Indirect measurement of blood pressure is carried out without violating the integrity of blood vessels and tissues. Methods based on the principle of balancing the pressure inside the receptacle is a well-known external pressure, is called Compression. Most prevalent method of compression using an inflatable cuff placed on the limb or vessel and providing a uniform circular compression of tissue and blood vessels. The first compression sleeve for measuringarterial pressure has been proposed in 1896, Riva-Rochchi (S. Riva-Rocci). Most common in medical practice, a sound, or auskultativny, the method of indirect measurement of blood pressure by Korotkov using sphygmomanometer and phonendoscope.

Compression methods for measuring blood pressure recorded by the extreme values of the measured value at time interval of observation. Information on variations in pressure by this method are not recorded. Roughly the curve of blood pressure can be obtained from rheogram or sfigmograma respective blood channel. Measured by indirect method of maximum and minimum blood pressure shall be plotted curve.

Rheogram of the pulmonary artery. Two cardiac cycles.

Measurement of venous pressure may also be indirect methods. For this proposed two methods: compression and hydrostatic. Compression techniques have proved unreliable and were not applied. From the hydrostatic method is the simplest method Gertnera. Watching the back surface of the hand when lifting it slowly, say at what altitude decreases vein. Distance from the atrium to the level of this point is a measure of venous pressure. The reliability of this method is also low because of the lack of clear criteria for the full balance of external and intravascular pressure. Nevertheless, the simplicity and accessibility make it useful for the tentative evaluation of venous pressure.