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Biomedical subjects

D S Lebedev

Publications and source records attributed to D S Lebedev.

6 recordsLinked to original sources

[Prognosis of the severity of acute pancreatitis by the neural network method].

For prognozing the character of the development of acute pancreatitis a neural network of the direct spread of the signal was developed with 15 inlets, 5 neurons of the latent layer and two outlets. The network was trained with the help of an algorithm of an inverse spread of the error. The sensitivity of the produced prognostic model was 100%, specificity at admission--70%, on the first day--80%, on the second and third day--90%. Before the moment of hospitalization 57 patients were observed during 72 hours. The diagnosis was confirmed in all cases by the methods of computed tomography with contrast amplification.

APACHE↗

[Effects of the dual chamber electrocardiostimulation on the systolic and diastolic function of the myocardium].

An assessment of the indicators of the systolic and diastolic functions of the left ventricle was made in 52 patients against the background of electrostimulation with a dual chamber electro-cardiostimulator with different atrioventricular delays (185, 125 and 79 ms). Different variants of the reactions to electrostimulation with a shorter atrioventricular delay were detected: the positive dynamics of the diastolic indicators was registered in the hypertrophic type of the diastolic dysfunction, aggravation of the diastolic disorders--in the restrictive type.

Adult↗

Photoreceptor coupling and boundary detection.

Electrical coupling between photoreceptors results in the extensive spreading of output potentials along the syncytium of photoreceptor terminals. This smoothing of output potentials seems to make spatial resolution worse. However, the photoreceptor noise that is considered to be non-correlated both in space and time is smoothed to the greater extent than the correlated potential difference across the boundaries between areas of different brightness. This improves the signal-to-noise ratio more for more extended boundaries and favours lowering the threshold so that they can be detected more easily during the subsequent processing. The results have a striking parallel with a well known dependence of contrast threshold on stimulus size as measured psychophysically.

Contrast Sensitivity↗

[The structure of neuropsychic disorders in the workers of a large industrial enterprise].

The structure of neuropsychic and psychosomatic disorders was examined in workers of a large electrotechnical enterprise. Screening methods were used in the form of two questionnaires: screening of patients of the ambulatory Department of the Leningrad Research Institute of Neurology and Psychiatry as well as a multipurpose questionnaire for screening worked out at the Chair of Psychiatry, medical Psychology and Narcology of the Donetsk Medical Institute. Results of the study are described.

Adolescent↗

[Characteristics of anesthesia in trauma surgery in children with severe burn injuries].

The authors analyze total anesthesia in 347 children with thermal injuries, subjected to traumatic operations involving massive blood loss. A characteristic feature of total anesthesia in children subjected to early necrectomies was a lower dose or refusal from cholinolytics for premedication, endotracheal multicomponent narcosis with ketamine, fentanyl (promedole) in the minimal doses in parallel with inhalation anesthesia by fluothane traces and a nitrous oxide-oxygen mixture with at least 50% oxygen. The optimal initial dose of nondepolarized myorelaxants in burnt children is 30-50% higher than the recommended dose and is determined by the size and depth of injury. For controlled myoplegia, the doses of nondepolarized myorelaxants for subsequent injections should be 1.5-2.5 times lower than the initial dose. The duration of pancuronium and arduan effects depended on hepatorenal function. Tracrium provided regulated myorelaxation in children with burns even in cases with hepatorenal dysfunction. A high rate of massive blood loss and early development of multiple organ failure in children with thermal injuries prompted us to develop infusion-transfusion therapy for traumatic operations involving massive blood loss. The volume of blood loss is estimated from the area of necrotic tissues removed and the type of necrectomy. Qualitative composition of transfusion mixture and the rate of transfusion is determined by the rate and volume of blood loss, level of hemoglobin and hematocrit, and metabolic disorders during the operation. Prolonged ventilation of the lungs is recommended for children with thermal injuries after operations involving blood loss of 1 circulating blood volume or more. These measures decreased the incidence and severity of complications involving the hemodynamics, oxygen status and metabolism in tissues, and improved the reparation.

Adolescent↗

[Increase in the information content of thermograms by compensating for tissue heat conduction].

There exist two groups of factors responsible for distorsion of thermograms, these are a subdued temperature relief due to thermal conduction of tissues and equipment-caused distorsions. Such distorsions lower the informativeness of thermograms which hampers the selection of diagnostic signs. A method is proposed which enables it to partially compensate distorsions through application of Viener's method of re-establishing distorted images, based on the use of the à priori information on the distribution of temperature on the surface of the body and on the probable properties of thermal fields. The equipment-caused distorsions are then considered to be insignificant. The proposed algorythm of re-establishment has been tried out on the image of blood vessels in the rabbit's ear and on the factual image of the thermal field, the thermograms of mammary glands.

Animals↗