Method of assessment of autoregulation of the cerebral circulation

 

(57) Abstract:

The invention relates to medicine, namely, neurology, neurosurgery, functional and ultrasound diagnostics. Underwent transcranial dopplerography. Examine reactions of the brain and Central hemodynamics in light physical activity in the form of 20 sit-UPS in 30 seconds and calculate the indicators: the index of cerebral autoregulation (IMAR) and the consistency of cerebral autoregulation (SMARA), the formula

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If the index of cerebral autoregulation less 22% in men and less than 34% in women and/or negative value of the indicator of the viability of cerebral autoregulation concluded impaired autoregulation of cerebral circulation; when the index of cerebral autoregulation is greater than or equal to 22% in men, greater than or equal to 34% in women and a positive indicator of the viability of cerebral autoregulation make the conclusion about the absence of impaired autoregulation of cerebral circulation. The method allows to increase the reliability of the test. 2 Il.

The invention relates to medicine, namely, neurology, neurosurgery, functional and ultrasonic diagnostics, and can be used to assess sosho of the brain are of great medical and social importance due to the high prevalence and serious consequences for human health, such as stroke and vascular dementia. According to statistical studies of cerebrovascular disease in Russia ranked second among all causes of death of the population, second only to coronary artery disease. For effective treatment of vascular diseases of the brain, it is crucial to obtain detailed information about the state of cerebral hemodynamics and its regulation. One of the most important regulatory mechanisms of cerebral blood circulation is cerebral autoregulation.

There is a method of assessment of autoregulation of the cerebral circulation by using a compression test under the control of transcranial dopplerography [Giller, S. A. A bedside test for cerebral autoregulation using transcranial Doppler ultrasound. // Acta Neurochir. (Wien). - 1991. - Vol. 108, 1-2. - P. 7-14]. The method consists of short-term compression of the common carotid artery (CCA). After registering background values of the linear blood flow velocity in the middle cerebral artery (MCA) is the compression ratio of the same name WASP for 5 cardiac cycles, then the speed is 10-15 seconds. After the termination of the compression WASP in the rate of rise of the linear flow velocity (overshoot) and decline in the peripheral the impunity of non-response of Central hemodynamics on clamping of the WASP, since it is known that the reduction of pressure in the carotid sinus in compression OSA causes a reflex increase in systemic arterial pressure; according to indices of cerebral autoregulation from the development and operation of the collateral circulation in the brain and low precision associated with a significant increase in the error of calculation of an index of autoregulation during typical for an adequate response of cerebral hemodynamics small drop of blood flow velocity in the MCA at the time of clamping of the WASP. In addition, a significant disadvantage of this method is the risk of embolic lesions of the brain when performing cross-clamping in patients with atherosclerotic plaques in the area of the carotid sinus.

The closest achieved a positive result is a method of assessment of cerebral autoregulation using test induced non-pharmacological hypotension [Aaslid R, Lindegaard, K. F., Sorteberg W, Nomes H. Cerebral autoregulation dynamics in humans. // Stroke. - 1989. -Vol. 20, 1. - P. 45-52], adopted for the prototype. It consists in a comparative analysis of changes in systemic blood pressure and the linear velocity of blood flow in the arteries of the base of the brain in response to acute reduction of blood pressure. The latter is achieved by the rapid release of air from the linear blood flow velocity in the middle cerebral artery. In healthy individuals, in contrast to persons with impaired autoregulation, blood flow velocity in the MCA is returned to the original level before the normalization of HELL. Evaluation of test results provides the calculation of the index of cerebral autoregulation rate according to the formula, which represents the relative change in cerebrovascular resistance, expressed as a percentage and divided by an accounting period of time. The lower the index value, the more severe the condition is autoregulation.

An important disadvantage of this method is its lack physiology, as in natural conditions of human life hypotension is much less typical reaction systemic hemodynamics compared with hypertension. In addition, the implementation of the method requires the involvement of more complex equipment such as the monitor, the AD used, usually in the intensive care unit, for simultaneous recording in real time not only the flow velocity in the MCA, but the average AD. This way for safety reasons not applicable in persons, sudden drop in blood pressure in which it is undesirable (for example, in heart failure).

A positive result declare the NCI autoregulation of cerebral circulation, as well as simplifying the procedures and reducing the time of the study using transcranial stress dopplerography.

This objective is achieved in that the method of assessment of autoregulation of the cerebral circulation is carried out by transcranial stress dopplerography, while conducting a study of the reaction of the brain and Central hemodynamics in light physical activity in the form of 20 sit-UPS for 30 seconds, then calculate the index of cerebral autoregulation and an indicator of the viability of cerebral autoregulation formula and obtained values make the assessment.

Light physical activity is a common stress factor in everyday life, which makes a very physiologic its use for the assessment of cerebral autoregulation. Performing light exercise is accompanied by significant changes in systemic hemodynamics, including AD, which makes it promising for the assessment of autoregulation of the cerebral circulation. Use the easy option load allows you to activate the mechanism of autoregulation of the cerebral circulation, without affecting the individual characteristics of physical performance to test ivalsa application of maximal and submaximal loads to identify the limit of the reserve capacity of the coronary circulation). In addition, the use of submaximal and maximal workloads significantly expands contraindications to the test, particularly in individuals over the age of 40 years.

To assess autoregulation of cerebral hemodynamics calculate the indicators: the index of cerebral autoregulation (IMAR) and the consistency of cerebral autoregulation (SMARA) by the formulas and the values of the indicators concluded a violation of the autoregulation of cerebral blood flow or lack thereof.

The method is as follows.

The patient laid on the couch in the supine position. On the working surface of the ultrasonic sensor for transcranial studies (phased ultrasonic sensor apparatus Spectra Masters" company "Diasonics, USA with a frequency of 2.25 MHz) put a small amount of ultrasound gel. Transcranial ultrasonic sensor fitted between the outer margin of the orbit and ear on a line corresponding to the upper edge solovideo bone, in the areas of greatest thinning scales of the temporal bone. In this zone by changing the angle of the sensor conducting the search and discovery of ARS. Further, all studies carried out on the side with the most waragai, - on the side with the best ultrasonic window.

B M1 or M2 segment MCA register Doppler spectrum frequency shift. Correction of the angle between the direction of the ultrasonic beam and the direction of flow, its value should not exceed 60o.

After obtaining a stable signal in the "freeze frame" conduct measurement of peak systolic blood flow velocity in the MCA alone (Vps(0)).

In parallel with the study of cerebral blood flow measure systolic and diastolic blood pressure at rest using a tonometer (PS,a(0)and RD,a(0)respectively.

Examined the patient gets up from the couch and runs 20 sit-UPS for 30 seconds, then lay down on the couch on his back. In M1 or M2 segment MCA register Doppler spectrum frequency shift. Correction of the angle between the direction of the ultrasonic beam and the direction of flow, its value should not exceed 60o.

In Fig. 1 shows an image of middle cerebral artery Doppler mode mapping; volume control is installed in the vessel lumen. Bottom: Doppler spectrum frequency shift; arrow indicates the separation of the Doppler freeze" conduct measurement of peak systolic blood flow velocity in the MCA after exercise (Vps(FN)).

Simultaneously measure systolic and diastolic blood pressure after exercise using a tonometer (PS,a(TN)and PD,a(TN)respectively.

Fixing dopplerography blood flow in the MCA mode "freeze frame" and the measurement of blood pressure after the patient physical activity performed in the course of time not exceeding 15 seconds.

Calculate the average hemodynamic HELL alone by the formula of Jicama:

Pm(0)=PD,a(0)+(PS,a(0)-Pd,a(0))/3,

where

Pm(0)- the average hemodynamic HELL alone, mm RT. Art.;

PS,a(0)- systolic blood pressure at rest, mm RT. Art.,

PD,a(0)- diastolic blood pressure at rest, mm RT. Art.

Calculate the average hemodynamic HELL after physical activity according to the formula of Jicama:

Pm(FN)=PD,a(TN)+(RS,a(TN)-RD,a(TN))/3,

where

Pm(FN)- the average hemodynamic HELL during exercise, mm RT. Art. ;

PS,a(TN)- systolic blood pressure during exercise, mm RT. Art.,

PD,a(TN)- diastolic blood pressure during exercise, mm RT. Art.

Calculate the index of cerebral autoregulation and indicator sostojatel the tion, %;

SMARTM- the consistency of cerebral autoregulation in men;

SMARTF- the consistency of cerebral autoregulation in women;

Vps(0)peak systolic velocity in the middle cerebral artery alone, cm/s;

Vps(FN)peak systolic velocity in the middle cerebral artery during exercise, cm/s;

Pm(0)- the average hemodynamic pressure at rest, mm RT. Art.;

Pm(0)=PD,a(0)+(PS,a(0)-RD,a(0))/3,

where

PS,a(0)- systolic blood pressure at rest, mm RT. Art.,

PD,a(0)- diastolic blood pressure at rest, mm RT. Art.,

Pm(FN)- the average hemodynamic pressure during exercise, mm RT. Art.

Pm(FN)+PD,a(TN)+(RS,a(TN)-RD,a(TN))/3, where

PS,a(TN)- systolic blood pressure during exercise in mm RT. Art.;

PD,a(TN)- diastolic blood pressure during exercise in mm RT. Art.;

constants,

where

M1=(-0,4048);

M2=0,4079;

M3=(=-0,2475);

M4=(-0,1207);

M0=0,3084;

F1=0,2677;

F2=0,2792;

F3=(-0,3727);

F4=(-0,4737);

F0=(-0,2377);

Conclusion on the violation of the autoregulation of the cerebral circulation makes the tel SMARA negative, there has been a violation of autoregulation of the cerebral circulation. When IMAR greater than or equal to 22% in men, greater than or equal to 34% in women and indicator SMARA positive autoregulation of cerebral circulation is not compromised.

According to the formula

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was calculated the IMAR. The average values of this index in healthy and sick, is shown in Fig.2. The chart shows that the values of the IMAR healthy were significantly higher than in patients.

Clinical example.

The patient And in 71 years. History 8660. The diagnosis of Atherosclerosis of the aorta and its branches. Stenosis of the left internal carotid artery 78%. Stenosis of the right internal carotid artery 52%. Pathological C-shaped tortuous proximal segment of the right vertebral artery. Dyscirculatory encephalopathy stage I of cerebral atherosclerosis and hypertension. The clinical picture was dominated by complaints about headaches and memory impairment.

When performing transcranial duplex scanning of arteries of the base of the brain revealed a decrease in reserves of collateral cerebral circulation (peak systolic blood flow velocity in the left MCA in compression of the same name Ecowaste blood flow in the left MCA was only 12.7 per cent, which corresponds to the lack of functional reserve of cerebral hemodynamics.

Conducted quantitative assessment of autoregulation of cerebral blood flow by the claimed method.

Measurement of peak systolic blood flow velocity was held in the left middle cerebral artery, as in the case of narrowing of the internal carotid arteries more pronounced stenosis was noted in the left ICA (78%) compared with right ICA (52%). Peak systolic velocity in the left MCA alone Vps(0)amounted to 98.1 cm/s, systolic blood pressure at rest PS,a(0)amounted to 146 mm RT.art., diastolic blood pressure at rest PD,a(0)67 mm RT.art., peak systolic velocity in the left MCA during exercise Vps(FN)was 105,6 cm/s, systolic blood pressure during exercise PS,a(TN)amounted to 153 mm RT. Art., diastolic blood pressure during exercise PD,a(TN)was 56 mm RT.article.

Mean BP at rest Pm(0)and after physical activity Pm(FN)it was calculated by the formula Jicama:

Pm(0)=PD,a(0)+(PS,a(0)-RD,a(0))/3=67+(146-67)/3=93,33 mm RT.article.,

Pm(FN)=PD,a(TN)+(RS,a(TN)-RD,a(TN))/3=56+

(153-56)/3=88,33 mm RT. Art.

Was ruturaj the formula:

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Index of cerebral autoregulation was 13,74% and was less than 22%, and the viability of cerebral autoregulation was equal -9,38, i.e. negative. On this basis it was concluded breach of autoregulation of the cerebral circulation.

Thus, the claimed method allows to detect the violation of the autoregulation of cerebral blood flow using quantitative diagnostic criteria evaluate the response of the cerebral circulation and Central hemodynamics in light physical activity according to color duplex scanning.

Method of assessment of autoregulation of the cerebral circulation by the method of transcranial dopplerography, wherein conducting a study of the reaction of the brain and Central hemodynamics in light physical activity in the form of 20 sit-UPS for 30 s, calculate the index of cerebral autoregulation and an indicator of the viability of cerebral autoregulation by formulas

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where IMAR - index of cerebral autoregulation %;

SMARTM- the consistency of cerebral autoregulation in men;

SMARTF- the consistency of cerebral autoregulation in women;

Vps(0)- peak satelitarna cerebral artery during exercise, cm/s;

Pm(0)- the average hemodynamic pressure at rest, mm RT. Art. ;

Pm(FN)- the average hemodynamic pressure during exercise, mm RT. Art. ;

constants,

whereM1= (-0,4048);

M2= 0,4079;

M3= (-0,2475);

M4= 0,1207;

M0= (-0,3084);

F1= (-0,2677);

F2= 0,2792;

F3= 0,3727;

F4= (-0,4737);

F0= (-0,2377);

and if the index of cerebral autoregulation is less than 22% of men and less than 34% in women and/or negative value of the indicator of the viability of cerebral autoregulation concluded impaired autoregulation of cerebral circulation; when the index of cerebral autoregulation is greater than or equal to 22% in men, greater than or equal to 34% in women and a positive indicator of the viability of cerebral autoregulation make the conclusion about the absence of impaired autoregulation of cerebral circulation.

 

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FIELD: medicine; medical engineering.

SUBSTANCE: method involves applying ultrasonic Doppler echolocation techniques for scanning blood circulation at selected area of cardiovascular system, determining blood circulation velocity vector projections and calculating blood circulation speed. Echolocation is carried out by using at least three non-complanar probing ultrasonic rays set at angles relative to selected area of cardiovascular system in the range of 0-80°. Selected blood circulation area orientation angles are measured relative to scanning ultrasonic rays and Doppler frequency shifts in each measuring channel are determined. Blood circulation speed is calculated as where ω0i is the radiation frequency of ultrasonic oscillation in ray I, Δωi is the Doppler frequency shifts in measuring channel i, V is the ultrasonic wave propagation speed in the medium, ϑk is the blood circulation speed in selected area, ϑki is the blood circulation velocity projection to scanning ray i, a,b,c,h,k,n11,n12,n13 are the coefficients depending on ultrasonic rays orientation. The device has measuring unit having ultrasonic transducers and electronic unit having switch, high frequency oscillator, calculating unit, indication and control unit. The measuring unit is manufactured as bracelet which segments are connected to each other by means of adjustable hinges and has gages for measuring lateral segment orientation angles relative to the central segment and gages for measuring ultrasonic transducer orientation angles relative to the i-th segment where i = 1,2,3, connected to calculating unit, switch, indication and control unit connected to high frequency oscillator, ultrasonic transducers of the measuring unit are connected via the switch to the high frequency oscillator.

EFFECT: high accuracy of measurements; wide range of functional applications.

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