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The effect of microwaves of 2355 MHz and 50 microW/cm2 on rat respiratory system has been investigated. On the basis of the experimental results and a priori suggestions a mathematical model has been developed to describe the process observed. Its structural and functional block-diagram is proposed permitting to define the mechanism of action of SHF field.
A survey throughout world literary output concerning physiology of respiratory system in pregnancy was made in this work. Metabolical changes caused by the increase of progesterone and other substances concentration and changes of the mechanics of ventilation connected by diaphragm raising caused by the growing uterus was discussed.
Imaging of the respiratory system developed with exceptional rapidity in North America during the spring of 1896, after Roentgen's discovery of X-rays in November 1895, largely because of the efforts of a unique physicians, Francis H. Williams. With great zeal, this pioneer used fluoroscopy for early detection of tuberculosis and other life-threatening chest disorders. By the summer of 1896, he had accumulated more than 100 volumes containing tracings of clinical chest fluoroscopy. As a result of his extensive clinical experience, his dedication to patients' welfare, and his sense of scientific inquiry, several inventions and many landmark clinical observations were made in the first few years after the discovery of the X-ray. These included (1) the invention of a "densitometer" for standardized measurements of relative X-ray attenuation of the lung, (2) the invention of a "seehear" device to correlate auscultative findings and fluoroscopic observations, (3) the recognition that fluoroscopy was more accurate than percussion for estimating mediastinal displacement, (4) the discovery that clinically occult tuberculosis and congestive heart failure could be detected with fluoroscopy, (5) the documentation that unilateral chest disease caused decreased ipsilateral ventilatory compliance and increased contralateral ventilation, (6) the identification of the classical imaging characteristics of tuberculosis, pneumonia, pneumothorax, tension pneumothorax, pleural effusion, hydropneumothorax, emphysema, congestive heart failure, and air trapping. In April 1896, Dr. Williams described the "air bronchogram" in a radiograph of a patient with pneumonia.
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We measured the compliance of the respiratory system (Crs) at 4 different tidal volumes (VT = 2.5, 5.0, 7.5, 10.0 ml/kg) in 29 mechanically ventilated newborn infants and determined the VT associated with the highest Crs ("optimal" VT) and with the lowest Crs ("worst" VT). Crs depended on the VT in all newborn infants investigated. The "optimal" VT most frequently observed was 2.5 and 5.0 ml/kg and the "worst" VT most frequently observed was 2.5 and 10.0 ml/kg. Mean Crs at the "optimal" VT was 62.3% higher than at the "worst" VT. The "optimal" VT was lower (2.5 ml/kg) in newborn infants with controlled ventilation than in newborn infants with intermittent mandatory ventilation (5.0 ml/kg). We conclude that it may be useful to determine the VT associated with the highest Crs in order to avoid unnecessarily high inflation pressures for the mechanical ventilation of newborn infants. Further studies are needed to assess long-term effects of such a Crs guided respirator therapy.
Airway resistance (Raw) can be measured throughout the respiratory cycle by whole body plethysmography. Total resistance of the respiratory system (Rrs) can be measured from the relaxed expiration that follows end inspiratory occlusion. The purpose of this study was to compare the two methods in normal infants and in infants with airway obstruction of different types and severity. Fifteen infants with essentially normal lungs aged 24.6 +/- 18.0 (SD) wk, nine infants with congenital stridor aged 36.0 +/- 17.3 wk, and eleven wheezy infants aged 20.1 +/- 11.3 wk had simultaneous measurements of Raw and Rrs. Rrs was similar to Raw both during inspiration and expiration in the normal infants, to all expiratory Raw in those with congenital stridor, and to all inspiratory and early expiratory Raw in the wheezy infants. Raw was markedly and significantly higher than Rrs during mid and late inspiration in infants with congenital stridor and during late expiration in the wheezy infants. We conclude that Rrs is a good estimate of Raw in normal infants and of early expiratory Raw in all infants. In infants with airway obstruction, Rrs does not reveal the dynamic changes in Raw during tidal breathing, nor can it differentiate between infants with upper and lower airway obstruction.
The endocrine cells and nerves of the respiratory tract of the reptile Podarcis hispanica were investigated by immunocytochemistry under light microscopy. Immunoreactivities were more numerous in the lung than in the trachea. In the tracheal epithelium, endocrine cells immunoreactive to PHI, PYY, and Leu-enkephalin were detected, while immunoreactivity to serotonin, calcitonin, CGRP, PHI, and Leu-enkephalin was found in pulmonary endocrine cells. Numerous nerve fibers positive to NSE, PGP9.5, chromogranin, tyrosine hydroxylase, calcitonin, CGRP, bombesin, substance P, VIP, NPY, and PYY were found in the lungs. In addition, neurons positive to NSE and PGP9.5 were also found. Immunoreactivities to PHI and PYY in cells and to NSE, PGP9.5, chromogranin, tyrosine hydroxylase, calcitonin, CGRP, and PYY in nerves, were reported first in the respiratory system of reptiles.
Impedance measurements of the respiratory system by means of the forced oscillation technique were performed in a group of 20 COPD patients before and after inhalation of 0.400 mg salbutamol. A slight, but statistically non significant decrease of resistance is observed at all frequencies from 12 to 52 Hz. Increase of reactance values reached a statistically significant level at all frequencies except at 24 and 52 Hz. It is hypothesized that the increase of reactance in these patients can be explained by an increase of capacitance due to an increase of airway compliance or a decrease of peripheral resistance according to Mead's analogon of the lungs.
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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.
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 consumption of coffee is a very old and popular habit. It is possible that it may have an effect on the respiratory system and on the regulation of respiration. Apart from the manifestations of hypersensitivity linked to the handling of green coffee, the consumption of coffee can have different effects. On the one hand it has a beneficial effect on bronchospasm. On the other hand its consumption has been suspected of contributing to the development of chronic airflow obstruction (COPD) and also in the genesis of bronchial cancer, without, however, its responsibility being proven in a clear fashion. In fact, in these two latter pathological circumstances, the causal relationship is probably indirectly linked to the fact that there is a strong positive correlation between the consumption of coffee and of tobacco. Finally the consumption of coffee increases ventilatory frequency in normal subjects and also in the course of COPD, and if taken in large quantities by pregnant women, there is an increased risk of neonatal apnoea in the newborn, by an abrupt cessation in the caffeine level.
Unit activity data revealed an obvious interrelationship between the brain vocal and respiratory systems. Modification of evoked reaction of the vocal system depends on stimulated central nuclei and parameters of stimulating electric current. The threshold of evoked vocal reaction is higher than the threshold sufficient for modification of respiration and neuronal activity. The data obtained suggest that not all the structures related to the respiratory regulation bear control over the generation of species specific cries.
Spectrum analysis is proposed as a method for analyzing biologic time series data that arise in the study of respiration. A mechanical model of the respiratory system is used to provide a theoretical basis for the interpretation of the air flow spectrum in terms of a physically defined energy concept. We show that under certain conditions the flow variance is proportional to the mechanical work of breathing, and indicate how this new parameter is related to conventional measures of respiratory function. An example is presented to describe the computational procedure and to illustrate the graphical aspects of cross-spectrum analysis.