RU2087126C1 - Method for measuring relative lumen of main arterial blood vessels - Google Patents

Abstract

FIELD: medicine. SUBSTANCE: method involves recording main blood vessels oscillogram in course of pressure growing in pressure measurement cuff in the frequency band of 0.05-40 Hz. The written curve is traced with straight lines passing through vertices. Pulse wave amplitude A is measured at the first point of intersection of straight lines in diastolic area. The value determines blood vessel lumen increment at the moment of systole. The diastolic blood vessel lumen is determined as difference of the pulse wave amplitude at the second point of intersection of straight lines in diastolic area and the value of A. EFFECT: wide set of data required for describing cardiovascular system state.

Description

 The invention relates to medicine, in particular to physiology and cardiology, can be used in both clinical and experimental studies.

 In oscillographic studies, when measuring blood pressure indicators (see Savitsky N.N.), they often use such a “tool” as the “oscillographic indicator” (OP), the maximum amplitude oscillation in the oscillogram, which reflects the amount of clearance of arterial vessels and is used to assess vessel tone in dynamics. If we conduct a physical analysis of the genesis of OP, we can see that its value depends on cardiac output, peripheral resistance, tonic state, and on the lumen of the vessel in diastole and its increment in systole.

 The essence of the invention is to determine the cross-sectional area S (lumen) of the main arterial vessel in diastole and its increment dS during systole during registration of oscillograms of arterial vessels. In combination with blood pressure indicators obtained on the same waveform, a number of additional hemodynamic indicators characterizing the state of the human cardiovascular system (CVS) can be calculated. (See K. Karo. Blood circulation mechanics, M. Mir, 1981).

 To solve this problem, a volumetric arterial waveform is recorded, the true volumetric signals of which fully reflect the regularity of the processes occurring in the arterial vessel and their amplitude-time relationships are preserved under the influence of increasing pressure in the cuff.

The main requirements for the registration system of volumetric arterial waveforms are:
rectilinear amplitude-frequency characteristic (AFC) of the channel of oscillographic signals throughout the through path of conversion and amplification to the visible registration of an analog signal in the frequency range; - lower cutoff frequency F _ng 0.05 Hz (time constant t _ng 3.0 s) with a cutoff at the level of 0.7 from 30 to 40 dB / dec; upper cutoff frequency F 40 Hz;
linear characteristic of the transformation along the entire path of the oscillographic channel;
ensuring registration and calibration of a linear set of pressure in the pinch measuring cuff from 0 to 200 300 mm Hg with an error of not more than ± 2 mm Hg

time linear pressure gain in pinch measuring cuff from 0 to 300 mm RT.article determined by the rate of pressure gain 4-5 mm Hg / s;
Oscillographic channels and cuff pressure marks should be synchronized in time.

 The above characteristics of the measuring system, in addition to the first, are also used in the prototype method.

 When using modern technical means, the implementation of these requirements, including the boundaries of the frequency range, is not difficult.

 Electrical waveform signals and pressure marks in the measuring cuff are simultaneously recorded on two tracks of the recorder tape and analyzed.

 A block diagram of one embodiment of the measurement system is shown in FIG. one.

 The system for registering volumetric arterial waveforms consists of pneumatic and electronic components: a compression device (1) with a control system for dialing and depressurizing (2) from a pinch cuff (3), a converter of pneumatic signals into electric signals (4), channels for amplifying oscillographic signals (5) and signals of the pressure value in the pinch cuff (6), the recorder (7).

 To explain the principle of measuring the lumen of the arterial great vessel in FIG. 2 shows a diagram of the formation of a volumetric arterial waveform.

The very meaning of a volumetric arterial waveform lies in the nature of the recorded signals, since the pulse curve is nothing more than the value of the increment of the lumen, multiplied by the length of the vessel under the cuff, that is, the volume. At the end of the diastolic period, the volume U of the section of the main vessel under the cuff is:
U = S • L,
where S is the lumen (cross-sectional area) of the vessel in diastole;
L is the length of the section of arterial vessel under the cuff.

The following systolic blood flow changes the measured volume by:
dU = dS • L,
where dS is an increment of the lumen of the vessel under the action of systolic ejection of blood.

 Since the value of L remains almost constant throughout the entire measurement cycle, the amplitude of the oscillations on the oscillogram is proportional to the lumen of the vessel changing under the cuff.

With the beginning of the increase in pressure in the cuff, compression of the investigated section of the vessel occurs, as a result of which the oscillations in the oscillogram slightly increase. When the pressure in the cuff (P _m reaches or slightly exceeds the diastolic pressure in the vessel (P _m > P _min ), the lumen of the vessel in the diastole begins to decrease relative to its previous level, since P _m prevents its full opening in the diastole.

At the point of equal pressure of the diastolic pressure in the vessel and the current pressure in the cuff, the oscillation amplitude "a" is proportional to the increment of the vessel lumen (dS) at the time of systolic ejection. When the pressure in the cuff reaches the average dynamic pressure (P _m > P _cf ), the lumen of the vessel at the end of the diastolic period is zero, the vessel under the cuff at this moment is closed by the pressure of the cuff. However, the next systolic blood flow, creating pressure on the walls of the vessel, equal to the lateral systolic pressure (P _bs ), which is higher than P _cf , opens the vessel to the previous value. This moment corresponds to the first maximum oscillation “A” on the waveform (proportional to the clearance dS + S), which often exhibits flattening at the base (the “closure wave” of the vessel according to Savitsky). In the diagram (Fig. 2), the lumen dS + S corresponds to the radius R + dR of the vessel, the amplitude "a" is proportional to the increment of the lumen dS with a radius dR. The amplitude difference "Aa" is proportional to the lumen of the vessel in diastole.

 In FIG. 3 presents a real oscillogram of the examined P, where an example of determining the values of "A" and "a" is given. To measure these indicators, it is necessary to circle the waveform with contour lines along the bottom in the diastolic and vertices in the systolic parts, designate the inflection points of the contour and measure the oscillation amplitude "a" proportional to dS at point 1 and the oscillation amplitude "A" proportional to dS + S at point 2. A value proportional to S is found as the amplitude difference "Aa".

 In the above example, "a" is 6 mm, "A" is 20 mm and "Aa" is 14 mm. The arterial vessel deformation coefficient in P during the examination was dS / S 3/7.

 It should be noted that the data on the lumen of arterial vessels are given in relative values, with a corresponding calibration of the amplitude values, it is possible to obtain the absolute values of the lumen of the vessel in diastole and its increment at the time of systole.

 The determination of the values of "A" and "a" is desirable to combine with the measurement of blood pressure, then by calculating significantly increases the information on the state of the cardiovascular system of the subject.

 The technical result of the proposed method is that the registration of true volumetric oscillations of blood vessels with minimal amplitude-time distortions allows you to measure their geometric characteristics, and in combination with blood pressure values to obtain additional information about the human blood circulation by simple and accessible methods.

Claims (1)

 A method for the relative measurement of the lumen of the arterial vessels, including registration of oscillograms of arterial vessels in the process of increasing pressure in a pinch measuring cuff, followed by electrical and graphic conversion, characterized in that the volumetric oscillatory signals of arterial vessels are linearly transformed and recorded in the frequency cavity of 0.05 40 Hz, the recorded curve in one registration cycle is circled along the vertices in straight lines, and in the diastolic part at the first point Intersections measure the amplitude of the pulse wave "a", and at the second point of intersection, the amplitude of the pulse wave "A", the increment of the lumen of the vessel at the time of systole is determined by the value of "a", and the size of the lumen of the vessel into the diastole as Aa.

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