Possibilities to increase reliability and accuracy of blood pressure measurement taking into account blood hydrodynamics and biomechanics of processes during compression of shoulder tissues with a pneumatic cuff

Systolic and diastolic BP values are determined guided by measurement signals (Korotkoff tones, oscillations). The source of these signals are hydrodynamic processes occurring in the artery under the influence of cuff pressure on the upper arm. The article is devoted to the study of these processes. The value of body tissues pressure on the artery walls is equal to the value of air pressure in the cuff only at the middle of the cuff and smoothly decreases to zero to its edges. Such non-uniformity of distribution of body tissues pressure on the artery walls is caused by the physical property of elasticity of their shape, which was not taken into account earlier. Therefore, the equality of the value of blood pressure on the artery walls from its inner side and the value of body tissues pressure on the artery walls from its outer side is possible only at one point. At this point, the open part of the artery passes into its constricted part, and the point itself is called the boundary of arterial constriction. The pulsations of blood pressure in the artery caused by the heart cause rhythmic movements of this boundary along the artery. Therefore, the arterial walls open up when the constriction boundary is moved in the distal direction. When the convergence boundary is moved in the proximal direction, the walls of the artery connect. During systole, when the blood pressure exceeds the air pressure in the cuff, the boundary of compression moves distally across the middle of the cuff. At the same time, a blood flow front is formed beyond the middle of the cuff, moving towards the distal edge of the cuff. When this edge is reached, the artery opens across the entire width of the cuff. In the diastole periods following systole, the blood pressure decreases. As a result, the blood pressure drops below the air pressure in the cuff, and the arterial wall at the midpoint of the cuff interconnect again. In this case, there is a re-boundary of constriction moving in the proximal direction. Thus, the hydrodynamics of blood in the artery is completely determined by the movements of the boundary of its compression. This hydrodynamics is substantiated theoretically and confirmed experimentally. It is shown that oscillations of air pressure in the cuff, Korotkoff tones and surface pulse waves are different consequences of a single biomechanical process, which allows us to consider in detail the formation of oscillations, surface pulse waves, as well as to put forward a physically justified version of the Korotkoff tones. 

1. Chazov I.E., Oshchepkova E.V., Zhernakova Y.V. DIAGNOSTICS AND TREATMENT OF ARTERIAL HYPERTONIA (Clinical Recommendations).2015. Cardiologicheskiy vestnik, No.1.

2. Kaarls R., Accred. Qual. Assur., 2007, vol. 12, рр. 435-437. DOI: 10.1007/ s00769-007-0301-6.

3. Savitsky N.N. Some methods of research and functional evaluation of the circulatory system. Medgiz.1956.

4. Romanovsky V.F. RomanovskayaA.M. To the question of non-invasive oscillometric method of arterial pressure measurement. Functional diagnostics.2009; No.1: 94-96.

5. Romanovskaya A.M., Romanovsky V.F. Physical and metrological aspects of methods of arterial pressure measurement with application of compression cuff. World of Measurements. 2018; №2: 32-44.

6. Romanovsky V.F., Romanovskaya A.M., Nenasheva E.A. Problems of ensuring the uniformity of blood pressure measurements. Metrologia. 2020; № 2: 46-71.

7. Romanovskiy V. F., Romanovskaya A. M., and E. A. Nenasheva E. A. MEDICAL AND BIOLOGICAL MEASUREMENTS PROBLEMS OF ENSURING THE UNIFORMITY OF BLOOD PRESSURE MEASUREMENTS. Measurement Techniques.2020; Vol.63, No.6: 493-502.

8. Eman A.A.BIO-physical bases of blood pressure measurement. 1983. Medicine.

9. Kositsky G.I.Sound method of arterial pressure research.1959. Medgiz. Moscow.

10. Hargens, A.R., McClure, A.G., Skyhar, M.J., et al.: Local compression patterns beneath pneumatic tourniquets applied to arms and thighs of human cadavera. J. Orthop. Res. 5, 247-252 (1987).

11. Pshenitsin A.I., Mazur N.A. Daily monitoring of arterial pressure.2007, Medpraktika-M, Moscow.

12. Romanovskaya A.M., Bezzubchikov V. A., Kotova N. A., Mikhailov V. A., MishutinA.V. Medical Progress through Technology1992, № 18:125-130.

13. Romanovskaya A.M. Method and device for indirect determination of arterial pressure.1981, Patent SU 895405.

14. Romanovskaya A. M. Method of indirect measurement of arterial tension and a device for wave registration.1987.US Patent 4,653,506.

15. Romanovsky V.F., Romanovskaya A.M. Oscillometric method of indirect measurement of arterial pressure and a device for wave registration.1987.US Patent, 65,506. of arterial pressure measurement and a device for its realization.2021. Patent RU 2763653.