[Consensus SOCESP-SBC on electrocardiography by Holter system].
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Biomedical subjects
Publications and source records attributed to R Terzi.
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The records of 608 intravenous drug addicts and 124 hemophiliacs diagnosed in 1985 to be seropositive for HIV were reviewed to identify patients with thrombocytopenia. The records of 54 drug addicts (8.9%) and 14 hemophiliacs (11.2%) who had chronic thrombocytopenia were then followed through June 1989 to estimate the incidence of bleeding episodes. The records of 55 HIV-seronegative patients with idiopathic thrombocytopenic purpura (ITP), comparable for age, platelet count at diagnosis and duration of follow-up, were used for comparison. Patients with ITP were significantly different from those with HIV-associated thrombocytopenia in having a higher proportion of females (M/F ratio 13/42 v 53/15, p less than 0.001) and more intensive treatment (treated: 62% v 21%, p less than 0.001; splenectomized 37% v 1.5%, p less than 0.001). The incidence of major bleeding was not significantly different in drug addicts, hemophiliacs and ITP patients (0.98, 1.82 and 1.17/100 patients/year). Among drug addicts, bleeding was significantly more frequent in women than in men (3.4 v 0/100 patients/year, p less than 0.05). Our results indicate that the incidence of major bleeding in patients with HIV-associated thrombocytopenia is low and similar to that observed in more intensively treated ITP patients.
It is often very difficult to quantify the potential thermal stress in jobs characterized by sudden variations of energy expenditure and thermal overload for time periods of short duration. Heart rate varies rapidly with the changes of energy expenditure and thermal load and the application of the mathematical model, proposed by Givoni and Goldmann for prediction of heart rate response to work in hot environments, to values of the physiological parameter, continuously measured during the periods of work and rest, allows the calculation of the two components of the HSI stress index (Er, Emax) from which to derive safe times of exposure. In this study practical applications of the theoretical method are verified in the control of the potential thermal stress of workers engaged in the carbon coke production. In that job the variability of thermal conditions make unfeasible a complete and whole evaluation of thermal overload only based on the measure of the microclimatic environmental parameters.
The discontinuous exposure to environmental working noise often brings about risk situations hardly assessable by means of phonometric measurements and studying the exposure time, even if accurate. The use of the personal dosimetry can simplify the measurements and give a time-weighted value (Leq) comparable to a fixed limit value. Such a measurement is effective only for the considered time (usually a work shift); nevertheless it is assumed to be representative of the usual exposure to the job even though the variability of the working conditions constitute a limiting factor. In this work we tried to verify the possible use of the measurements of environmental sound pressure levels given by the dosimeter every 0.25 sec. The first aim being the study of the type of distribution of these values (during 5 consecutive shifts) and the estimate of mean and standard deviation values. The mean and the standard deviation values were used to get a OTL (one sided tolerance limits) usually employed for assessing the working chemical pollution. The second aim being the compliance control and the possible need of more measurements.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The authors study the statistical distribution and the graphical representation of the urinary chromium values investigated during three consecutive years in three work environments of a same plant: polishing 1 degree, electrotyping, polishing 2 degrees, to evaluate the environmental situations of exposure and their variations. The adopted method, based on the graphical representation of the values in logarithmic coordinate paper, allows to quickly and carefully calculate the percent of the workers having urinary chromium values above the prefixed limits.
After measuring the heart rate values of workers unfolding a standardized job made under unfavourable microclimatic conditions, the Authors calculate them by application of a proposed biophysical model starting from ambient climatic conditions, energetic expenditure and thermal resistance of the clothing. The results, compared by means of statistical methods, do not show any significant difference between the two methods. Therefore is also possible the proposal of the use of the biophysical model for the prevision of heart rate under standardized working conditions.
The Authors measure the environmental microclimatic parameters (dry bulb temperature, wet bulb temperature, globe temperature, natural wet bulb, air speed, vapor pressure) in twenty working sites. Starting from the values obtained, they calculate the safe exposure times for works under unfavourable thermal conditions by means of three different methods (time weighted average WBGT, allowable exposure time-AET, required sweat rate index). Finally they verify the results obtained by application of a biophisical model proper to calculate the response of rectal temperature to changes in metabolic rate and environmental conditions.
A biophysical model for studying the response of the rectal temperature to changes in metabolic rate and environmental conditions has been utilized to establish the safe exposure times for works at risk of thermal stress. The prediction of the rectal temperature allows to evaluate for how long the heat load due to metabolic rate is lasting after the work stopping in the period of recovery.
The Authors examine the variations of the levels of PbB and EPP in 39 workers at known lead exposure and evaluate the capacity of these parameters to follow the measured decreases of the environmental pollution. They conclude that the variations of the mean PbB values are well related to environmental pollution and that the diagram on the probability paper of median values and their corresponding standard deviations allows to calculate the number of exposed workers with biological values above a fixed limit.
The diagnostic meaning of the functional platelets modifications (particularly those of spontaneous platelet aggregation = P.A.) in cardiovascular pathology has been recalled. It is emphasized that, in order to have significantly predictable data on eventual pathological alterations in case of deviations of values considered normal, one has to use methods that do not differ from the real haemorheological conditions. A research has therefore been made with the purpose to evaluate the influence that variations of temperature may have on the samples collected and left to sediment (for the separation of the PRP) and the subsequent modifications of P.A. The research has been made in double on plasma sedimented at 37 degrees C and at room-temperature on 731 subjects, 289 of which were the casuistic groups for the subsequent statistic elaboration. With similar modalities in other 8 patients the eventual variations in excretion of beta-TG were looked for. The results have shown that there are important variations of the spontaneous P.A. rates, that the difference is always statistically very significant and that lowering the temperature of the samples favors an increase in beta-TG excretion . The Authors think therefore that only the sedimentation at 37 degrees C issues a plasma usefull for the further performing of platelets tests, while in the plasma obtained with sedimentation at room-temperature the platelets are perhaps already stimulated to an activation (and subsequently an aggregation) higher than the real one. Data obtained from a homogeneous group of subjects, healthy from a clinical point of view, allowed to fix the new range of normal values within 3% of aggregability . The mechanisms that lead to such different results are discussed. Emphasis is put on the fact that the spontaneous P.A. determined by the means mentioned seems satisfactorily near to the real clinical conditions. That's why the hypothesis arises that also other tests concerning platelet functions could be negatively influenced if they have room-temperature as a condition for plasma separation.
The working time in work places thermically uncomfortable must be limited in order to prevent the risk of thermal stress. In a previous study we have demonstrated that the best method for calculation of the safe exposure times is based on the required sweat rate index. In the present work we verified in different work places termically uncomfortable, grouped for equivalent values of WBGT index, the variability of the safe exposure times calculated by means of a method just now mentioned for various levels of energetic expenditure. The results point out the possibility of a mathematical relation between energetic expenditure, WBGT index and mean of safe exposure times.
The working time in work places termically uncomfortable must be limited in order to prevent the risk of thermal stress; the safe exposure times are based on the microclimatic parameters and the energetic expenditure required for the job. Hearth rate measure is proposed by various Authors as index connected with the energetic expenditure level and with the microclimatic conditions. In the present work the Authors realise the monitoring of a job uncomfortable for thermal conditions by means of the hearth rate measure of the workers. The results show the better accuracy of the purposed method in comparison with the application of the safe exposure times.
The Authors starting from the microclimatic parameters globe temperature (tg), dry bulb temperature (ts) forced wet bulb temperature (tu), natural wet bulb temperature (tun), speed of the air (v) observed every half an hour in greenhouses for tropical plants, evaluate the required sweating rate per hour during a specimen working shift for a known energetic expenditure. The sweating rate values calculated exceed by far the highest limits accepted for the workers perfectly acclimatized and impose the application of the working safe exposure times.
The Authors show that there is some relationship between WBGT microclimatic index and PMV thermic comfort index. This relationship can be noticed at various levels of energetic expenditure and for three values of thermic impedance from clothes used in working places in the four seasons.