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Biomedical subjects

Z Tabka

Publications and source records attributed to Z Tabka.

15 recordsLinked to original sources
PubMed1993

[Pulmonary emphysema: quantification using computed tomography and correlations with respiratory function tests].

Pulmonary emphysema can be defined in precise anatomical terms. Only histological examination of an entire lung will enable the extension and the severity of the emphysema to be fully assessed. The authors propose a visual score, using computed tomography to quantify emphysema in 61 subjects. 51 had chronic airflow obstruction (BPCO) and were divided into 31 chronic bronchitics (BC) and 20 emphysematous subjects (EP). 10 volunteers who were free of any respiratory pathology were chosen as controls. A visual score for the computed tomography was established for the subjects as a whole. Double reading of the data enabled the reproducibility of the method to be checked in 10 subjects (r = 0.98, p < 0.001). No emphysema was found in the 10 controls, the computed tomography score was appreciably more elevated in the EP subjects than in the BC group at 1.3 and 0.44 respectively (p < 0.001). In the BC, the computed tomographic score was not correlated with the PaO2 (r = 0.54, p < 0.001) and the FEV1 (VEMS) (r = < 0.44, p < 0.05). On the other hand, in the PE group, the score was correlated with the FEV1 (r = 0.52, p < 0.05) and the residual volume (r = 0.06, p < 0.05) and the total lung capacity (r = 0.63, p < 0.05) and the TLCO (r = 0.56, p < 0.05) and the TLCO/VA (r = 0.59, p < 0.05). The adoption of a visual computed tomographic score enabled the authors to find the correlations between pulmonary emphysema and the most specific tests of respiratory function.

Adult↗
PubMed1988

Effect of dry warm air on respiratory water loss in children with exercise-induced asthma.

The variation in respiratory water loss (RWL) over time, expressed as the mass of water vapor lost per liter (body temperature and pressure, saturated) of ventilation (MH2O), was investigated in two groups: (1) children with exercise-induced asthma; and (2) healthy children. Children were matched for age and sex and went without medication for at least 12 hours before each experiment. The children breathed dry warm air (TI = 28.4 degrees C +/- 0.3 degree C) for 15 minutes while bicycling at constant and moderate work load (50 W). The MH2O was measured by collecting and weighing the expired water vapor (1) at rest breathing in warm conditions of inspired gas (control values), (2) every five minutes during exercise while breathing dry warm air, and (3) four minutes after the end of exercise. Pulmonary function tests were performed before and six minutes after exercise. The results were abnormal only in children with exercise-induced asthma. During exercise, RWL significantly fell (compared to control value) at the tenth and 15th minute in both groups. Whereas normal subjects recovered their initial values for MH2O four minutes after stopping exercise, asthmatic children still had a reduction in respiratory water loss. During exercise, MH2O decreased a little more in healthy than in asthmatic children. The decrease in MH2O in both groups suggests that the means to fully humidify expired gas are overwhelmed by thermal stress. The lack of increase in MH2O in asthmatic children on stopping exercise suggests that the airway mucosa is unable to produce enough water vapor and is thus dehydrated and probably hyperosmotic.

Asthma↗
PubMed1987

Steady pressure-flow relationship in a cast of the upper and central human airways.

Pressure drops across the upper (larynx) and central airways of a human lung cast were measured at steady state inspiratory and expiratory flows. Air, He-O2 and SF6-O2 gas mixtures were used at tracheal Reynolds' numbers ranging from 145 to 30,000. The pressure-flow characteristics of the model were analysed using standard pressure-flow diagrams and Moody plots. We found that the asymmetry between inspiratory and expiratory resistances, observed in the central airways (larynx excluded), was markedly reduced in the presence of the larynx. However, static pressure differences were greater across the entire model of the upper and central airways than across the model of the five generations of the tracheo-bronchial tree (without larynx) at the same flow-rates. In addition, our results showed that the presence of the larynx tended to reduce the zone of fully developed laminar flow in the Moody diagram with the higher density gas, while extending the zone of turbulent flow even for the low density gas at low Reynold's numbers.

Airway Resistance↗
PubMed1987

Effect of breathing dry warm air on respiratory water loss at rest and during exercise.

The changes in respiratory water loss with time, expressed as the mass of water vapour lost per liter BTPS of ventilation (MH2O), and expired temperature (TE), used to calculate the relative humidity (ERH), were investigated in ten normal subjects while breathing warm dry air by mouth (PIH2O = 0 kPa; TI = 30 degrees C): at rest for a period of 35 min; during 15 min light muscular exercise (50 W); at increasing work load from 50 to 100 W between the 5th and 10th min of the exercise. The data collected were compared to those obtained in room air conditions (PIH2O = 0.68-1.3 kPa) and under conditions with slightly heated inspired air (TI = 28-30 degrees C). At rest, when breathing dry warm air MH2O and ERH fell during the first 15 min, while they recovered their initial values during the last 20 min. In contrast no differences in MH2O or ERH were observed when breathing ambient warm air. At constant and moderate work load for 15 min, the respiratory water loss fell significantly (compared to the 5th min) at the 10th and the 15th min when breathing warm dry air. The added hyperpnea which was obtained by increasing work load from 50 to 100 W between the 5th and 10th min of exercise did not further reduce MH2O and ERH. The transient fall in MH2O and ERH, which lasted at least 15 min either at rest or during muscular exercise, suggested that the mechanism underlying humidification of expired gas is overwhelmed by thermal stress. Since the upper airways mucosa is unable to saturate expired gas, this also suggested that the mucosa is dehydrated and probably hyperosmotic. The progressive recovery in MH2O and ERH after 15 min of warm dry air breathing at rest, suggest operation of a slow adaptive mechanism.

Female↗
PubMed1983

[Fetal macrosomia and the study of risk factors in maternal diabetes].

The authors report the results of a study performed in 142 women who gave birth to overgrown neonates. Among them, the incidence of diabetes was high: 7.75%. Older maternal age, maternal obesity and the former birth of large infants were also found to be risk factors for fetal overgrowth.

Adult↗