To the question of methods of determining the blood pressure

Abstract

On Tuesday, November 8, 1905, the 4th regular scientific meeting of the clinical military Hospital was held in the 20th auditorium under the chairmanship of N.I. Kulbin. A method for measuring blood pressure was proposed. The sounds in the stethoscope are currently known as "Korotkov tones".

Full Text

Based on his observations, the author concluded that a compressed artery in normal conditions does not produce any sounds. Using this circumstance, the author proposes an auscultatory method to measure blood pressure in humans. The Riva-Rocci cuff should be posed in the middle third of the arm; the pressure in the cuff is rapidly increased up to complete obstruction of distal blood circulation. Thereafter, letting the pressure in the cuff decrease, the artery just below the compression should be auscultated with a child stethoscope. At the beginning of the procedure, no sound can be heard. After the mercury column drops to a certain point, first a short sound appears, which indicates the passing of blood under the cuff. Consequently, the level of pressure when the sounds appear can be taken as the maximal blood pressure. A further decrease in cuff pressure is accompanied by compression murmurs on the artery, which later are again transformed into definite sounds (second ones). Finally, all sounds disappear. This indicates the free movement of the pulse wave; in other words, at this point, the minimal blood pressure becomes higher than the cuff pressure. Thus, the mercury readings at this moment can be taken as minimal blood pressure. The animal experiments gave confirmative results. The first sound appears earlier than the distal pulse (10–12 mmHg), for the palpation of the latter on the arteria radialis a stronger pulse wave is required.

A. Ya. Ivanov. How do you explain the origin of the sounds below the sleeve at the beginning and at the end of listening?

The speaker. In this case, the pressure in the sleeve is close to the minimum pressure in the artery, but it is still higher in the sleeve; when the blood wave slips, the vessel breaks apart and gives a short popping sound.

A. Ya. Ivanov. What difference did you observe between the maximum and minimum pressure in the brachial artery?

The speaker. The numbers I’ve got were extremely different, but normally between 25-35 mm. and more.

V. G. Bozhovsky. As far as I understand from your very interesting report, you explain the origin of sound phenomena (sounds, noise) in your very simple experience by purely local causes. The mechanism of noise formation is clear and does not require much explanation, but I cannot agree with you about the development of sounds on the spot. Your explanation of the origin of sounds below the sleeve, because of sudden fluctuations in pressure, for all its allure does not want to be considered the main, and probably the only source of sounds in the circulatory system — the heart. The sounds that can be heard in more or less large vessels, are undoubtedly transmitted through the blood stream, as a medium that conducts them very easily, from the slamming of the semilunar flaps of the aorta. In the vessels closest to the heart, if the latter are intact, we listen to the tone of the systole of the heart, after slamming the shutters, and in case of their violation, insufficiency, this tone is replaced by noise, both at the site of listening to the aorta, and in the vessels, e.g. carotid, etc. Both tone and noise are considered to be conducted into the vessel, not local. Below the sleeve, you don't hear any sound phenomena when it squeezes the shoulder, probably until the lumen of the brachial artery disappears completely. In animal experiments, you did not listen to anything, even when the first drops of blood begin to appear from the severed segment of the artery as the pressure in the sleeve decreases. You start listening to sounds, noises, and sounds again as soon as the blood flow begins to be more or less marked, so to say, i.e. when the blood wave becomes so large that it is able to conduct those sounds that are formed in the heart. Your assumption about the local origin of sounds in the vessel suggests, presumably, some active forces. Apart from smooth muscle, we do not know any other active force in blood vessels. And there is too little of it in a vessel such as the brachial artery, or rather, absolutely none, to attribute the origin of sounds in the vessel to it. Secondly, in terms of time, the development of sounds in your experience falls on the diastole of the vessel, and this state should be considered as passive, not active. In addition, blood pressure, the fluctuations of which you are trying to explain the development of sounds, is a collective concept: in addition to the known vascular tension, blood pressure, its fluctuations in one direction or the other, are created by energy, the force of heart contractions. In view of all that has been said, it seems to me that even if there were a reason to talk about the local formation of sounds in the vessels, there is still no way to reject their development in the heart. So far, I repeat, this is the only source.

The speaker. First of all, I must say that the sound-tone in this case is nothing more than the same compression noise, but the noise is so short-lived that it is perceived by our ear as a sound-tone; indeed, the slip of an insignificant part of the pulse wave occurs in such a small period of time (a fractional fraction of 1") that it would be surprising if such a slip would make noise. But I also have reason to assume that the loosening of the walls of the compressed vessel is also involved in the formation of these sounds-tones. If we assume that tones are formed in the heart and are only conducted, then as more favorable conditions for conducting them, there would be a complete absence of compression of the pulse wave, i.e., listening to the artery without any pressure, we would have to hear tone sounds, which is not observed under normal conditions. Finally, the complete disappearance of sounds with complete compression of the vessel lumen also speaks against the fact that sounds are conducted rather than formed on the spot (Autoreferat).

I. P. Shapovalenko. The formation of noise and sound during the gradual compression of an artery with a stethoscope has been known for a long time. (Compression noise and sound). In your experience, there was a gradual opening of a pre-compressed artery and the sound phenomena were naturally obtained in reverse order, with another faint sound following the appearance of noise. The first sound, before the noise, judging by your experiments on a dog, appears after the first drops of blood pass through a compressed artery much earlier than the pulse appears on the art. radialis, and therefore, by the appearance of this 1st sound, of course, it is more accurate to determine blood pressure using the Rivva-Rocci device than by pulse. It would be interesting now, while listening to the artery, to make observations with Dr. Uskov's device. His device apparently records the same moment when the first sound appears in your experience. The latter, as well as the noise in the comparison, is of local origin, since it was not heard above.

N. I. Kulbin. A complete reconciliation of the theories did not happen here. Some persons explain the origin of sounds differently than the speaker. Of course, this issue cannot be considered settled. How applicable is your method?

The speaker. I was working with normal vessels. Perhaps, in pathological cases, these sounds are formed by the vessels themselves.