CS209806B2 - Appliance for the pletysmography of the vein closure - Google Patents

Description

(54) 'Device for plethysmography of vein closure

BACKGROUND OF THE INVENTION The present invention relates to a device for performing plethysmographic examination of limbs by means of a vein occlusion.

By means of the device according to the invention, pathological changes of both the capillaries and the venous or arterial bed can be detected in a non-invasive way, as well as the results of surgical procedures or the effects of various chemicals in adults or ¹ in infants.

The modern man is substantially threatened by diseases of the circulatory system of the extremities. Previously, such methods of measuring and measuring devices have been required by which peripheral circulation, limb arterial occlusion in summary, · peripheral blood flow disorders, have been required, quite simply in outpatient conditions. Various vein occlusion devices have been developed for this purpose.

Known devices for plethysmography of the vein closure are provided with one or more investigated cuffs, a limb and a measuring transducer for observing the change in limb volume on the measured section. The measurements made with these devices are laborious and the results - measurements are not accurate,

The device according to the invention, the essence of which is that the output of the measuring transducer is connected to the input of the comparator - and to the input of at least one sensor -, will substantially reduce the laboriousness and achieve absolutely accurate measurement results. the output of the measuring transducer or pulse sensor or ECG channel is connected to the analyzer input to determine the characteristic points of the pulse waveform or ECG waveform, and the analyzer output is connected to one input of the control unit, the other input of which is connected - - with a comparator output while- one controller output is connected to the pneumatic unit input, its second output is connected to the · time-meter input, its third output is connected to the computer input -and its fourth, fifth and other outputs are connected ke. the second inputs of the sensing and memory circuits, wherein the second input of the computer is connected to the output of the time meter, the third, the fourth and the other inputs of the computer are connected to the outputs of the sensing and memory circuits. The apparatus, with its second outlet connected to the registration apparatus, one outlet of the pneumatic unit being -connected -with the first breather collar and the other outlet of the pneumatic unit being -connected -with the second breather-collar.

The object of the invention and its advantages over the prior art are evident from the description and schematic drawing in which they are shown in FIG. Fig. 1 - positioning of the collars and the measuring transducer on the examined limb, Figs. 2, 3 and 4 - respective graphs that apply to known devices, Fig. 5 - block diagram of the device according to the invention in an exemplary embodiment, Fig. 6 and 6b - graphs of the measurement performed by the device, in Fig. 7 - a block diagram of another embodiment of the device according to the invention.

The first breather cuff M1 (Fig. 1) is placed proximal to the leg to be examined and is suddenly filled with subdiastolic pressure. The venous reflux is thereby stopped for a longer period of time, but the arterial flow is not yet restricted in the first seconds. At the same time, the volume increases distally from the first collar M1. The increase in volume is indicated by a measuring transducer G disposed distal to the first collar M1. The nature of the volume increase, together with the arterial pulse curve, averaged value, is shown in Figure 2. Here and in the rest of the description, the relative change Δ v / v _{0 is used} , as this expression allows comparison of measurement results on limb sections with different initial volumes v ₀ .

It follows from the basic considerations that the change in relative volume change, i.e. the initial steepness of the curve, which occurs as a result of the sudden pressure increase in the first sleeve cuff M1 at time t = 0 is decisive for the arterial · bloodstream condition. the bloodstream does not yet interfere with arterial flow.

If, after such induced quasi-stationary isthava, the pressure in the first vent cuff M1 is quickly discontinued, then a venous outflow from the pathway, respectively. section after the first collar M1. The reduction in volume taken by the transducer G is shown in conjunction with the arterial pouch curve, the superimposed mean value, in FIG. It can easily be seen that the change in the relative volume change dv / / Vo / dt, that is the initial steepness of the curve that occurs at the time of pressure reduction, is an important diagnostic information for the venous bloodstream condition. to the first collar. If only the first bead cuff M1 is used, as described above, then the examination may extend to the entire limb path beyond the first bead cuff M1. However, if only a predetermined path is to be investigated, for example between the first collar M1 and the second collar M1, then a pressure greater than the systolic pressure is generated in the second collar M1. As a result, a path lying distal to the second cuff M2 can be excluded from the examination.

The variety of devices suitable for carrying out the method is given by the difference in the construction of the measuring transducer G.

The so-called water plethysismograph has a measuring transducer G which consists of a tank surrounding the limb end, the tank being closed and provided with a measuring aperture, having a steep wall on its outer part and filled with water, the water being heated to human body temperature. If pressure is applied to the first collar M1, then the volume changes which can be observed by means of a calibrated glass tube or capacitive transducer, etc., inserted into the metering orifice.

Another device works in an analogous way, in which there is air in the tank instead of water. Volume changes in the case of a closed tank may be indicated by a pressure change, in the case of an open tank by a pneumotachograph. Nowadays, a solution has been expanded in which volume change can be monitored by measuring the circumference of a given leg segment. It can be shown that there is essentially the following connection:

_ dV _of DL _and Lo (1) wherein V _o is _the initial volume, and L _o is the initial circuit.

This means that the relative volume change is twice the relative circuit change.

When examining the arterial or venous bloodstream, the problem is practically the same: the initial steepness of the curve at time t = 0 is to be determined and disturbing spontaneous volume changes due to pulse are superimposed on this curve (Figures 2 and 3).

In the case of conventional methods, the change in relative volume change is determined by drawing the tangent manually on the registration paper, for example in Figures 2 and 3 - lines A, B, which appears to be the best for assessing and knowing the relative change scale volume and duration are then calculated. It is clear that this method is cumbersome and that no acceptable accuracy can be assured.

By another known method, a faster but still inaccurate measurement can be realized. The principle of this method in the case of arterial bloodstream examination will be explained by means of Fig. 4. If, after inflation of the first puffing cuff M1, it crosses the object or the relative volume change of the examined limb section, a predetermined AVk / Vo value. the time meter a, after a certain time At, at time t _v , the instrument detects the current relative volume change AV _v / V _q . From the difference in relative volume change,

209808

6 existing at the time points t _k , t _v and z time, t, the initial slope of the curve can be determined by machine and immediately indicated.

Although this measurement is fast and the evaluation does not require manual intervention and no registration device is needed, its lack is obvious. That is, depending on the ratio of the time interval At, the pulses frequency and their amplitude, very deviating results may be indicated by the device with the same bloodstream disorders.

If, for example to change at a constant frequency and pulse amplitude value At AT, as can be seen from FIG. 4, then possibly end of the interval, i.e. _the time point t on the path pulsin diastolic wave.

The initial slope, which can be calculated from the interrelated values of,, AV _k / V ₀ and AV7V ₀ , is substantially less than the initial slope, calculated from the interrelated values Att, AV _k / V ₀ and AV _v / V ₀ .

Eliminate pulse disturbance and allow unambiguous, accurate, and automatic determination of the initial value of the relative volume change curve, respectively. an initial steepness of the relative volume change curve is achieved with the device of the invention.

5, the output of the measuring transducer G is connected to the input of comparator K and to the input of at least one sensing and memory circuit Si S2 ... S _n . The input of the PA analyzer, which is used to determine the characteristic points, i.e. the points of the same phase of the pulse curve, respectively. the ECG signal is connected to the output of the G-transducer, or the pulse sensor, or the ECG instrument. The PA analyzer output is connected to one VA controller input, while the other VA controller input is connected to the comparator K output.

One output of the control unit VA is connected to the input of the pneumatic unit PN, its second output is connected to the input of the oasis meter T, its third output is connected to one input of the computer RA, but its fourth, fifth and other outputs are connected with other inputs and Si memory circuits. . . S _n . The second input of the computer RA is connected to the output of said time meter T, while to its third, fourth and further inputs the outputs of the sensing and memory circuits Si ... S _n are connected. A pointing device M is connected to one output of the computer RA, a recording apparatus D is connected to the other output. One output of the pneumatic unit PN is connected to the breather cuff M1, its other output is connected to the other breather cuff М2.

¹ , according to a further embodiment, the output of the measuring transducer G is connected to the input of the comparator K, further to the input of the sensing and memory circuit and / or the analog-to-digital converter SD. To the input of the PA analyzer determining the characteristic points, respectively. points of the same phases of the pulse curve or the ECG curve, the output of the measuring transducer G or the pulse sensor P or the ECG channel is connected, while the output of the PA analyzer is connected to one input of the VD control unit. The output of the comparator K is connected to the second input of the control unit V, but one output of the control unit VD is connected to the input of the pneumatic unit PN, its second output is connected to one input of counting and memory unit RD, its fourth output is connected to the other input reading and storage units and / nobo analogue to digital converter SD.

The output of the sensing and memory circuit and / or the analog-to-digital converter SD is connected to the second input of the counting and storage unit RD, the output of the time meter being connected to the third input of the counting and steaming unit RD. T. One outlet of the pneumatic unit PN is connected to the first breather sleeve M1, the other outlet to the second breather sleeve М2. A pointer device M is connected to one output of the counting and storage unit RD, a recording device D is connected to the other output. The operation of the device according to the invention will be explained in the case of arterial blood speech by a block diagram in Fig. 5. primarily analog and measuring technology and by means of FIGS. 6a and 6b, which characterize the relative volume change AV _P / V _O induced pace.

When the measurement is started, the PN pneumatic unit is started by the VA control unit. The pneumatic unit is suddenly filled with a subdiastolic pressure, approximately 50 mmHg, and optionally, depending on the path of the limb to be examined, the second airflow cuff M1 is filled with a pressure greater than the systemic pressure.

The measuring transducer G, whose output is connected to the input of the sensing and memory circuit Si, is used to indicate the change in volume of the limb section. .. and comparator K. The input of the PA analyzer is connected to the output of the pulse sensor P, which is expediently arranged in the vicinity of the measuring point, or, the pulse sensor P, which is structurally connected to the measuring transducer G. to determine the time points of the pulse curve corresponding to the characteristic points, suitably to the systemic and / or diastolic points. At these times, the PA analyzer sends a synchronous or non-synchronous signal to the input of the VA control unit. characteristic impulses. Meanwhile, the measuring transducer G continuously senses the relative change in the volume of the leg section. If the volume change, respectively. the relative volume change exceeds a predetermined value that is expediently greater than the volume change caused by the systolic part of the pulse, or if the transient events occurring when the pneumatic unit PN is actuated have disappeared, see Fig. 6a AV _k / V ₀ , the comparator sends a preparatory pulse to the VA control unit. Then, the VA control unit receives the synchronous, resp. characteristic pulses, appropriate to the next characteristic point of the pulse curve (see Figs. 6a and 6b, time point t1, systolic time point of the pulse waveform), and at the same time a time meter T is excited and sends a command for the read and memory circuit Si amplitude value ÁVi / V ₀ . Thereafter, the control unit VA only considers the synchronous, respectively. characteristic impulse, which agrees with the earliest synchronous, respectively. a characteristic pulse, that is to say, belonging to the same phase of the pulse curve.

(See Figures 6a, 6b, time point tz, next systolic point of the curve) :. At the same time, the VA controller also turns off the time meter. T and send a command for the read memory circuit and SZ which memorizes the amplitude value AV2 ^ I / _O at the time t2. For this, the initial steepness of the relative volume change curve is determined from the output of the time meter T, proportional to the time t2 — ti = At, and from the output signals of the sensing and memory circuits Sr and Sz, proportional to the relative volume changes AVi / V ₀ and AV2 / V _O. according to: command of the control unit VA by the RA computer, which is. then pointing at the pointing device

M. the following connection applies:

AV2 _ AVi

- Vo__________Vo t2 — tl = tg cel = dV

Vo dt

2.

t = 0

The value thus determined corresponds with a good approximation of the theoretical initial steepness of the relative volume change curve.

6a and 6b, a case where the pulse sensor P has been disposed in the vicinity of the measuring transducer G or is structurally connected to the measuring transducer G has been discussed.

In this case, the corresponding points of the signals supplied or received are not between the corresponding signal points. no phase shift is transmitted by the measuring transducer G and the pulse sensor P. The same applies if, instead of the pulse transducer output P, the output of the measuring transducer G is connected to the input of the PA analyzer. In this case, the PA analyzer processes a pulse curve separate from the output of the measuring transducer G. A phase shift resulting from the pulse wave velocity occurs between the corresponding points of the signals transmitted by the measurement transducer G and the pulse sensor P. This phase shift does not interfere with the operation of the device, since the initial steepness of the relative volume change curve is also determined in this case by the points of the same phase of the pulse waveform, the superimposed signal transmitted by the measurement transducer G. Such a case can be seen in FIG.

AV4 AVT those ^four points and t2 \ Phase shifting is ti' TI and initial slope ai 'agrees with the initial ramp · ai specified time points ti and t2.

It follows from the foregoing considerations that time points belonging to characteristic points, expediently to the R-waves of the ECG signal, may be used for synchronization. Therefore, an ECG channel output signal can be output to the PA analyzer. In this case, the PA analyzer determines the time points belonging to the characteristic points of the ECG curve.

The control unit VA can also be designed such that the device determines the initial steepness of the relative volume change curve not by two downstream of the same points of the same phase of the signal emitted by the measuring transducer G, but by points of the same phase spaced apart. For example, if the timer T is switched ON at time t1 and off at time t4 by the control unit VA, the sensing and memory circuits S1 and T2, respectively, are switched off. S2 receives a command at the same time points t1 and t2, then receives the initial steepness of the relative change curve for the following modified form of expression (see Figure 6a):

dV

Vo dt

3.

t = O bridge of any path, or the ratio of these paths, or that the curve D can register a curve without disturbing pulse effects. Such a design is of significance when it is necessary to observe the area, the so-called filter path of the curve, describing the relative change in volume. As a result of a longer path or if the properties of the whole curve are to be investigated, other devices more suitable for this purpose, based on the principles of digital measurement, may be used. This solution provides less readings than equation 2 but accuracy is sufficient, especially in infants , since in this case a higher pulse frequency must be considered. It should be added that this solution increases the reliability of the measurement.

The control unit VA and the computer RA can also be formed such that, by using any number of sensing and memory circuits Si ... S _n , any curve paths describing the relative volume change can be observed. This can also determine p2 О 9 8 О 6 niches. This device is shown schematically in FIG. 7.

In the example, the embodiment of FIG. the first air cuff M1, the second air cuff M1, the measuring transducer G, the pulse transducer P, the ECG channel, the PA analyzer, the pneumatic unit PM, and the time meter T with the function shown in Fig. 5. the VD control unit is connected to the second input of said analog-to-digital converter SD. The VD control unit transmits commands to the sensing and memory circuit at time points corresponding to the characteristic points of the pulse waveform or the ECG waveform, and invokes additional commands to

Claims (1)

SUBJECT A vein closure plethysmography device comprising one or more bead sleeves and a transducer for volume change monitoring, characterized in that the output of the transducer (G) is connected to the comparator input (К) and to the at least one sensing and memory input circuit (Si, Sa ... S _n ), and at the same time the output of the measuring transducer (G) or the pulse sensor (P) or the ECG channel is connected to the analyzer input (PA) to determine the characteristic points of the pulse curve or ECG curve, and the analyzer output (PA) is associated with one input of the control unit (VA), the other input of which is connected to the output of the comparator (K), while one output of the control unit (VA) is connected to the input of the pneumatic unit (PN). the second output is connected 5 sheets of scanned scanned signal counting and memory. Initial slope of the relative volume change curve, respectively. any other parameters of the relative volume change curve are indicated by the counting and storage unit RD, and shown, respectively. indicated by the registration device D or the indicating device. M. In conjunction with FIGS. 5, 6a, 6b and 7, the function of the device for the investigation of the arterial bloodstream has been described. If the venous system is to be examined, then the measuring systems agree with each other, with the exception that in the latter case the measurement is carried out when a sudden pressure break of the first collar M1 is performed. The influence of venous pulse affects the measurement only insignificantly. OF THE INVENTION to a time meter input (T), its third output is connected to a computer input (RA), and its fourth, fifth, and other outputs are connected to second inputs of the read and memory circuits (Si ... S _n ), input of the computer (RA) is connected to the output of the time meter (T), to the third and fourth input of the computer (RA) are connected outputs of sensing and memory circuits (Si ... S _n ); device (M), its second output is connected to the registration device (D), one output of the pneumatic unit (PN) is connected to the first breather sleeve (M1) and the second output of the pneumatic unit (PM) is connected to the second breather sleeve (М2) .