Kipiani D., Mitagvaria N., Kipiani T., Gvindzhilia l.
l. S. Beritashvili Institute of Physiology, Georgian Academy of Sciences, Tbilisi *Laboratory of Medical Expert Systems "Anthropos Systems Lab", Vinnitsa, Ukraine
ABSTRACTS:
METHODS:
The method of tetrapolar reoencephalography (REG) occupies the special place among set of methods for research of cerebral circulation. The simplicity and non invasiveness have made this method irreplaceable in many medical applications, where it is necessary durably, in various conditions to receive the information about cerebral circulation. Technically, the method of REG developed almost perfectly, and the quality of a registered signal usually is quite satisfactory [4]. However, because its low adequacy and low reproducibility of received data, method of REG is frequently criticized. There are two main reasons that formed this kind of image concerning to REG method: 1) a various capacitive reactance in electrode-skin contact site, depending on a method of electrodes application and 2) problems with processing of reoencephalogram, more often which is connected to exact identification of a beginning and end of systolic wave. It is well known that REG gives the integrated information about blood flow in whole volume between electrodes and, accordingly, simultaneously reflects many processes: arterial inflow, capillary flow, venous outflow etc. Change of these processes is very diverse from systole to systole and finds the reflection on an integrated picture of REG, sometime essentially modifying reoencephalogram. Application of differential reoencephalography markedly reduces amount of errors at the analysis and essentially raises correctness and reproducibility received parameters of blood circulation [3]. The basic methodical problem of REG, is attempt to treat received data irrespective of correlation existing between cerebral circulation and central, systemic circulation. Despite well-known autonomy, processes proceeding in the system of cerebral blood flow regulation closely are related with system of central circulation. Condition of the latter can be rather adequately evaluated only by an estimation of the interrelated characteristics, such as volume of blood, vessels capacity, pump function of heart, blood flow, with consideration of circulation in such regions as lung, abdomen, lower limbs.
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Without knowing of certain characteristics of systemic circulation in two postural conditions – lying and standing [5,1], we are not capable correctly estimate the cerebral blood flow for human being. So, if we consider value 450 ml/min as a "norm" for cerebral blood flow, we easily put ourselves in impasse. At cardiac output (CO) equal 12000 ml/min, this value testifies about ischemia of a brain, and at CO equal 3000 ml/min it is expressed hypercirculation. But, usually, the value of CD at the moment of realization of reoencephalography is not determined. We do not speak yet about such parameters, as a ratio of systolic wave duration of REG to the duration of heart ejection's period, that could characterize the resistance of cerebral vessels; or about value of delay between the beginning of REG'S systolic wave and beginning of heart ejection, that would give the characteristic of passability of major cerebral vessels and other.
Thus, incomplete character of the received diagnostic information is a basic lack of being in use today method of REG. Taking into account the separate parameters (or even their group) of this or that region of cardio-vascular system (CVS), only partially reflects a condition of regional circulation and its basic haemodynamical mechanisms. It is clear that the possibilities of such diagnostic method will be limited as for reception of a generalized, integrated estimation, as well as for its practical, clinical use.
All above-mentioned proves necessity of development and improvement system of reoencephalography for reception of adequate diagnostic information, and estimation of main parameters of circulation.
We offer new, modified method of reoencephalography system for research of circulation in whole organism, and for its separate regions, including the brain. The method takes into account anthropophysiological peculiarity (connected with upright-walking) of human being and for realization of this method it is necessary to use the electrodes tapping according to Fig. 1:
Common network of current, formed by applied on forehead (over bridge of the nose) a disk electrode and ring electrodes, located in supramaleolar area;
Jointed system of potential electrodes, in which the disk electrode on a back surface of a neck is common for tapping from disk electrodes of a head's left (2) and right (1) sides, and neck's ring electrode use for tapping from chest;
Ring electrode at a level of sword-shaped branch, is common for tapping from chest (3) and abdomen;
Ring electrode at a level of crests of pelvis is common for tapping from abdomen (4) and pelvis;
Ring electrodes at a level of tuberositas tibialis, are common for tapping from pelvis-femur (6-8 and 5-7) and shin from the left and right;
Ring electrodes in supramaleolar area used for tapping from shins at the left (10) and right (9).
After electrodes applied simultaneous registration of reogramm on all regions in a standing posture has to be carried out. Then, after 20 minute being lie, measurements have to be repeated in a laying posture.
Only differential reogramm is registered and its basic characteristics are read out. On the chest reogramm the amplitude of systolic wave and duration of heart ejection are determined, and on peripheral reogramm (including reoencephalogram) an amplitude is determined.
On chest differential reogramm by means of amplitude and duration of systolic wave the systolic volume (SV) is defined according to the formula [3]:
SV(ml) = 150 x L2/Z2 x Adif X Ti
where L – distance between electrodes (cm), Z – base impedance of chest, Adif. amplitude of differential reogramm (ohm/sec), Ti – period of ejection.
Value of:
CO = SV x HE
where HB is the frequency of heart beets
and other parameters are also determined: total peripheral impedance of vessels, arterial pressure, conditional values of volumes of blood in accordance with the base impedance of regions, arterial inflows of regions in accordance with amplitude of systolic waves of the appropriate regions etc. – it is total about 200 parameters.
On the basis of these parameters an integrated estimation of a condition of circulation in organism as a whole, on a lesser circle of circulation, on a greater circle of circulation in general and in separate regions will be carried out. The evaluation of cerebral circulation will be carried out by:
– Volume of blood – increase, decrease;
-Arterial circulation – hypercirculation, hypocirculation, arterial insufficiency;
– Types of arterial circulation – hypotonic, hypertonic, cardiac, perusal;
– Vessel's resistance – hypo- and hyper restiveness;
– Arterial impedance, determined by systemic pressure, pump function of heart and total
perfusion (that actually reflects circulatory ratio between vessels capacity, and basic mechanisms of perfusion);
– Type of venous circulation – hypo- and hypercirculation
– Volume of venous blood – without change of volume, with reduction of volume, venous stagnation, venous insufficiency;
– Circulatory maintenance of arterio-venous exchange – functionally active, functionally limited, non compensated, decompensated – is determined by arterial inflow, venous outflow and volume of blood.
Recently, the above described modified method of reography was realized as unique Computer Expert System "ANTHROPOS" manufactured by Laboratory of Medical Expert Systems "Anthropos Systems Lab".
In conclusion, it is necessary to emphasize, that an offered advanced method of reography with application of "Anthropos" allows:
– To bypass practically all restrictions, inherent in a classical method of reoencephalography;
– To receive the exhausting information not only about a condition of cerebral circulation,
but also on a complex of haemodynamical parameters of a total organism, that much raises informational validity of diagnostical conditions determined by indices of cerebral blood flow.
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