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Biomedical subjects

V V Nikitin

Publications and source records attributed to V V Nikitin.

At least 19 recordsLinked to original sources
PubMed1985

[Computational methods for determining the mean tissue doses during x-ray procedures].

The Soviet and Finnish authors presented a short description of two computer methods to determine doses in the patients' organs. Based on the general principles, such as a semiempirical mathematical description of dose fields and a realistic anthropomorphous phantom, these methods differed significantly in the algorithms used and ways of solving specific problems. The comparison of these methods and calculated dose values with the results of experimental measurements on the phantom showed a good convergence of the results. The divergence of calculated and experimental data by the values of the mean absorbed doses in the organs did not exceed +/- 35%. The advantages and prospects of the use of the computer methods for the evaluation of doses received by patients, were demonstrated.

Absorption↗
PubMed1985

[Concept of effective equivalent dose for medical irradiation].

The applicability of the concept of an effective equivalent dose to medical irradiation was substantiated. Some specific problems for calculating this value were discussed. The problem of a correct choice of a group of "the rest of organs" was considered. Basing on the mean estimation of the mean tissue doses received by patients in different x-ray studies a maximum of 6 organs was proposed for this group: the liver, kidneys, adrenals, stomach, pancreas, and spleen. It was shown that the same organs could be used in the calculation of effective equivalent doses from other (nonmedical) ionizing radiation sources.

Humans↗
PubMed1985

[Effect of x-ray spectrum transformation on bone marrow dose].

A study was made of change of the spectrum (spectral transformation) of x-ray radiation while passing through the soft tissue. Thirty-two depth spectra computed by the Monte-Carlo method and 16 experimentally measured spectra including 9 depth spectra taken from literature, were analysed. A method of the calculation of an absorbed dose in the red bone marrow with account of spectral transformation was described. It was shown that neglect of this factor caused regular underestimation of the assessment of medullary doses, patients were exposed to, during x-ray procedures. The error can reach 40% for doses at local points of the red bone marrow and 1-7% for mean medullary doses with regard to the type of x-ray procedure and regimen of its performance.

Bone Marrow↗
PubMedDate not supplied

[Intensity of basal metabolism and ratio of oxidized energy substrates in children with craniocerebral trauma].

Twenty-five children aged 2-14 years with isolated and combined craniocerebral injury were examined. Some of them underwent urgent neurosurgical interventions. Mechanical injury and intervention were regarded as aggressive factors. The basic methods were indirect calorimetry and intravenous prolonged glucose and fat tolerance test. The results indicate that in general, the intensity of basal metabolism and the ratio of oxidized energy substrates in children with craniocerebral injury correspond to the course of standard postaggressive reaction. Time course of changes in RQ, structure and share of basic energy substrates in the total energy produced confirm a general biological regularity of postaggressive metabolism: fat is oxidized predominantly during the initial period, while on day 5 inversion of fat and glucose oxidation values is observed.

Adolescent↗
PubMedDate not supplied

[Use of noninvasive assisted lung ventilation in children in intensive care units].

Thirty-six patients aged 2 months to 14 years were observed. Noninvasive assisted ventilation of the lungs (NAVL) was performed through Respironix Inc. masks (USA) with Puritan-Bennet 7200, Bear 1000, and Bear 750 respirators in the SIMV + PS, CPAP + PS modes with manual regulation of the supporting pressure level. Respiratory rate, heart rate, respiratory volume, pO2, pCO2, SpO2, stroke volume, and minute volume of the heart were evaluated. During development of central respiratory failure in the early postoperative period or in case of forced deep medicamentous neuroplegia NAVL normalized the external respiration function and promoted adequate ventilation of the lungs; in the majority of cases with development of restrictive respiratory failure (RF) it improved ventilation of the lungs and therefore no intubation of the trachea and transfer to forced ventilation was needed. NAVL is indicated as a component of multiple-modality treatment for obstructive RF.

Adolescent↗
PubMedDate not supplied

[Principles of intensive care during the acute period of severe craniocerebral trauma in children].

Prospective analysis of the course of severe craniocerebral injury (CCI) in 37 children showed that the results of treatment depended on methods of intensive care. In children the outcome of CCI depends primarily on adequacy of maintaining effective cerebral bloodflow during the acute period of CCI irrespective of the terms and etiological factors of coma. Adequate cerebral perfusion pressure is attained with osmodiuretics, saluretics, and hemodynamic therapy. Hyperventilation is justified in cases with coma developing within 2 h after the injury; it should not lead to long (more than 1 h) decrease of PaCO2 below 28 mm Hg. The authors emphasize that every delayed decrease of consciousness after the injury should be thoroughly analyzed in order to rule out intracranial complications (epi/subdural and intracerebrai hematomas) in no more than 6 h, which is the maximal time allowed for decision making. Use of unapproved medical methods and drugs in children during acute period of severe CCI is ineffective and even hazardous, because it distracts the physician's attention to negligible details of treatment; in addition many of such drugs have side effects.

Acute Disease↗
PubMedDate not supplied

[Central hemodynamics during therapeutic sedation in children under artificial pulmonary ventilation].

A total of 46 patients, aged 9 to 14, who underwent the artificial ventilation of the lungs (AVL) for diffusive purulent peritonitis with laparostoma, spastic syndrome, destructive pneumonia, and crania-cerebral trauma of different severities, were investigated. The patients were divided into 3 groups with respect to a medicamental sedation. Group 1--bolus dosing of a 20% solution of gamma oxy-oil acid (GOOA), 75-100 mg/kg; group 2--bolus dosing of a 1% solution of thiopental sodium (5-7 mg/kg); and group 3--micro-flow introduction of dormycum (0.1 mg/kg x h). The central hemodynamics was studied by the NCCKOM apparatus ("Bomed", USA) by applying a non-invasive technique. Stroke volume, cardiac rate, circulation minute volume, mean arterial pressure and general peripheral vascular resistance were determined. The sedation level was assessed by Cook's and Palma's scale (1989). The above investigations showed that all used techniques insured a satisfactory functioning of the cardiovascular system, but the highest stability of parameters was registered in the group, in which COOA was applied. The highest level of sedation and comfort was registered in the group of patients, which received dormycum. A conclusion was made on the basis of the conducted study that the technique of the micro-flow introduction of dormycum indicated for AVL in children is an adequate and stable sedation technique producing a minimal impact on the hemodynamics.

Adolescent↗