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Biomedical subjects

B Bake

Publications and source records attributed to B Bake.

At least 145 records · Page 8Linked to original sources
PubMed1975

Voluntary changes of thoracoabdominal shape and regional lung volumes in humans.

We measured regional lung volumes from apex to base in humans during changes in thoracoabdominal shape which we monitored with magnetometers. In erect subjects, voluntary changes of shape at FRC did not change regional volume distribution. In supine subjects, the effect of negative pressure applied to the abdomen and a similar thoracoabdominal configuration achieved by voluntary means were studied. The distribution of regional volumes in both situations was the same as that measured during relaxation at the same overall lung volumes. We concluded that neither voluntary changes in shape nor negative abdominal pressure influenced the human pleural pressure gradient. This result, which differed from findings in animals, was probably because the human chest was relatively stiff and behaved with one degree of freedom; all parts of the human rib cage changed dimensions proportionally while negative abdominal pressure distorted the rib cage of animals.

Abdomen↗
PubMed1975

Regional distribution of a 133Xe labelled gas volume inspired at constant flow rates.

We measured the regional distribution of 480 ml of 133Xe labelled gases inspired from FRC at constant inspiratory flow rates ranging from 0.1 to 6 litres/s. The gases used were air and 20% O2 in helium. At low inspiratory flow rates the gas was preferentially delivered to the dependent region of the lung. At maximal inspiratory flows, all regions of the lung were more evenly ventilated. The rate of redistribution was found to be slower and more even than in previous studies using smaller volumes of inspired gas. Assuming equal and synchronous changes of pleural surface pressure, these results can be reasonably predicted by the mechanical time constant theory applied to a simple two-compartment lung model based on equal regional resistances. Breathing the HeO2 mixture did not significantly change ventilation distribution at any flow rate.

Functional Residual Capacity↗
PubMedDate not supplied

Respiratory resistance and impedance magnitude in healthy children aged 2-18 years.

Two hundred eighteen healthy children aged 2 to 18 years were studied using a modification of the forced oscillation technique. Reference values with height as predictor were determined for total respiratory resistance and impedance during inspiration, expiration, and throughout the whole respiratory cycle at an oscillation frequency of 4 Hz and, in a subpopulation of 61 children, at frequencies of 2 and 12 Hz. Mean total inspiratory resistance, determined at 4 Hz, decreased with growth from 1.3 kPa X 1(-1) X s at 2 years of age to 0.3 kPa X 1(-1) X s at 18 years. Variability in the results between individuals, expressed in terms of coefficient of variation, was found to be +27% and -21%, respectively, and within individuals, 9%. Resistance during expiration was on average 16% higher than during inspiration and the variability within individuals was 11%. A marked decrease in resistance was found in small children when the frequency was increased from 2 to 12 Hz. The frequency dependence of respiratory resistance observed in small children changes gradually with growth, in parallel with the reduction of total respiratory resistance, to an adult pattern in which no significant change in resistance can be noted between frequencies of 2 and 12 Hz.

Adolescent↗
PubMedDate not supplied

Effects of electric arc welding on ventilatory lung function.

Respiratory symptoms, spirometry, forced expiratory flows, and the nitrogen closing volume test were studied in 119 welders and 90 controls, matched with respect to age, height, and smoking habits. Respiratory symptoms according to a questionnaire were more prevalent in the welders. No short-term changes of the measured variables during the day or week attributable to welding were found in twenty-one nonsmoking welders. Compared to the controls, closing volume and closing capacity (i. e., closing volume + residual volume) were significantly higher, and total lung capacity and the amplitude of the cardiogenic oscillations in the nitrogen curve were significantly lower in the welders who were nonsmokers or exsmokers, whereas there were no differences among smokers. These findings in welders may be attributable to deposition of welding fume particles in peripheral small airways or alveoli.

Aerosols↗