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Biomedical subjects

A A Morozov

Publications and source records attributed to A A Morozov.

At least 19 recordsLinked to original sources
PubMed2000

Evaluation of a thoracic bioimpedance cardiac output monitor during cardiac catheterization.

OBJECTIVE: To evaluate the accuracy and precision of an advanced thoracic bioimpedance cardiac output monitor by comparing it with conventional thermodilution. DESIGN: Prospective data collected from 47 patients undergoing routine cardiac catheterization. The new bioimpedance system differs from its predecessors in electrode system configuration, advanced signal processing, use of a modified Kubicek equation, and a reliable estimate of left ventricular ejection time from the time derivative bioimpedance signals. SETTING: A cardiac catheterization laboratory in a university affiliated teaching hospital. PATIENTS: A series of 47 relatively homogenous patients undergoing routine cardiac catheterization for suspected cardiac disease. MEASUREMENTS AND MAIN RESULTS: The data from the first 20 patients was used to determine optimal values for coefficients in the bioimpedance cardiac output equations. The coefficients found were used when the system was tested in the subsequent 27 patients. For the last 27 patients, a total of 80 simultaneous pairs of cardiac output measurements were made by conventional thermodilution and by thoracic bioimpedance. The mean difference between the two methods was -0.31 L/min and the standard deviation of the differences was (0.76 L/min). The correlation coefficient was r2 = .72 (p < .001). CONCLUSIONS: The correlation between conventional thermodilution and thoracic bioimpedance cardiac output estimates was good and the standard deviation of the differences was lower than that reported for commercially available devices. The system can be used in the cardiac catheterization lab for reliable and continuous noninvasive measurement of cardiac output.

Cardiac Catheterization↗
PubMed1999

Evaluation of a new advanced thoracic bioimpedance device for estimation of cardiac output.

OBJECTIVE: This study is an evaluation of a new thoracic bioimpedance cardiac output monitoring system which incorporates a modified form of the Kubicek equation and a method of estimating the left ventricular ejection time from the time derivative bioimpedance signals. METHODS: The performance of the new system was compared with conventional thermodilution in a porcine model. One hundred and ninety nine (n = 199) paired measurements of thermodilution cardiac output (TDCO) (range 1.20-18.00 L/min) and thoracic bioimpedance cardiac output (BICO) were collected in 7 pigs. The bioimpedance measurements were adjusted for the animal's weight and chest circumference, thus compensating for the differences in the anatomy of pigs when compared to humans. Data were compared using weighted correlation coefficient and Bland-Altman analysis. RESULTS: The weighted correlation coefficient between TDCO and BICO values was 0.87 (n = 199). The Bland-Altman technique yielded a precision of the device of +/-1.69 L/min with a bias of 0.11 L/min. CONCLUSION: The results from the porcine study show that the new system performed well over a wide range of cardiac outputs, comparing favorably with data from other new bioimpedance cardiac output devices currently available in the market.

Animals↗
PubMed1996

[Mechanism of action of electromagnetic fields biologically adequate to man].

The paper analyzes 10-year experience in making experimental observations and clinically using electromagnetic fields (EMF) biologically adequate to man. Basic investigations of the electromechanical process that lead to the occurrence of currents in the bone tissue and blood vascular walls in their functional deformation were conducted. They showed that the piezoelectric effect is the most marked in the intact bone tissue. Experimental studies determined the amplitude and shape of impulses of currents emerging in the intact bone tissue of the extremities and in the walls of blood vessels during pulse blood filling. The bioelectric tissue metabolism changes in various human locomotor abnormalities. The lost part in the diseased area can be restored by means of external EMF. On this basis, devices for human biologically adequate electromagnetic therapy were designed. The efficiency of each session of electromagnetic therapy was evaluated from the normalization of blood circulation in the diseased area. The efficiency of this therapy in vascular disease was noted to depend on the synchronization of the generated electromagnetic pulse with the pulse wave of a patient and its phases. An experiment on 13 intact mongrel dogs was made to reveal the impact of EMF biologically adequate to man on bone marrow hemopoiesis. EMF 2 was found to have a stimulating effect on granulocytopoiesis. Platelet counts were elevated in the peripheral blood of animals. Analysing 2000 clinical cases and canine experimental findings provided evidence for the following mechanism of action of the electromagnetic fields biologically adequate to man. The fields exert a primary initial and virtually rapid action on the active areas of nerve structures and smooth muscle of blood vascular walls. They show a primary, but slower action on blood cells and on the vascular endothelial structure. There may be a secondary impact of EMF on some endocrine glands, which causes changes in the protein metabolism of a biological object and appears as stimulation of granulocytopoiesis and depot platelet release into the peripheral blood stream.

Adult↗
PubMed1991

[Pseudotuberculosis in the Krasnodar Territory. The clinico-epidemiological characteristics of its morbidity and the biological properties of its strains].

Group cases of pseudotuberculosis, first registered at health-restoring institutions of the health resort of Gelendzhik (the Krasnodar Territory), are described. The etiology of these cases of the disease was established on the basis of clinico-epidemiological data, specific seroconversion in 66% of the examined patients and the isolation of Yersinia pseudotuberculosis strains from the feces of four patients. The combination of signs observed in the isolated strains, viz. the presence of plasmids with molecular weights of 75 and 45 MD, resistance to bactericidal factors of normal human serum and autoagglutination in cell culture medium, made it possible to consider these strains to be virulent. The cases of infection were probably caused by the use of fresh cabbage salad. The study of 3,128 rodents caught in the Krasnodar Territory, including those caught in the area of the health resort, resulted in the isolation of 105 Y. enterocolitica strains and strains of 5 other Yersinia species, but not Y. pseudotuberculosis strains. The concept on the saprozoonotic nature of pseudotuberculosis was substantiated.

Antibodies, Bacterial↗
PubMed1990

[Neurophysiological mechanisms of aphasia in epilepsy].

The EEG, visual and auditory evoked potentials were examined in 4 patients with aphasia-epilepsy. All the examined manifested focal discharges of high-amplitude acute waves, peaks and peak-wave complexes in the temporal leads on the left or on the side of assumed dominance according to speech. The same leads showed transformation of auditory and visual evoked potentials to peak-wave complexes. The intensity of epileptic focal discharges on the EEG correlated with the gravity of aphasia, whereas effective treatment bringing about suppression of epileptic discharges in the temporal parts favoured speech recovery. Obviously, speech disorders in patients with aphasia-epilepsy are caused by neurodynamic disorders of information transfer and processing in the speech zones of the temporal lobe.

Aphasia↗
PubMed1986

[Oscillating visual evoked potential in epilepsy].

The authors studied visual evoked potentials (VEP) at the O, P, C and T leads in response to light flashes of 0.09, 0.18 and 0.36 W/s in 19 normal and 43 epileptic subjects. In 75% of the patients the VEPs were characterized by a high amplitude oscillatory response (OVEP) in the form of a series of 5.5 oscillations with a 10 Hz frequency, the mean latent period of its development being 230 ms. In the normal subjects the OVEP was observed in only 30% of cases and had a lower amplitude, longer latent period and corresponded to the normal after-discharge according to all parameters. Some common features characteristic of the OVEP in epilepsy and the after-discharge in normal conditions suggest that the OVEP is generated by thalamic rhythmogenic mechanisms which are involved in the reaction earlier and more actively as a result of disinhibition of the subcortical multisynaptic systems. The OVEP is an indicator confirming the diagnosis of epilepsy.

Adolescent↗
PubMed1983

[Water-electrolyte and hemodynamic aspects of the lasix test in patients with various courses of hypertension].

Forty-two hypertensive patients and seven controls were subjected to the lasix test (20 mg intravenously) followed by the assessment of the time-course of water and electrolytes excretion as well as by arterial pressure measurements. Prior to the test the authors, using isotopic and non-isotopic dilutions, determined the indices of central hemodynamics and sodium, potassium and water distribution in the body. In more than 60% of the patients, the diuretic, sodium- and potassiumuretic response to the administration of lasix was higher than in control. In the patients with essential hypertension, the nature of this response did not depend on the initial level of the arterial pressure, cardiac index, rate of glomerular filtration, content of the total metabolic sodium and potassium, or on the amount and distribution of water in the extracellular and intracellular spaces of the body. The patients with an excessive response to lasix had a significantly lower baseline urine excretion of stable sodium, a higher sodium concentration in the red blood cells and, in cases of stable hypertension, a higher activity of plasma renin as well. Modifications in hypotensive therapy are proposed in relation to the response to lasix administration.

Adult↗