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PubMedDate not supplied

[Impact of physical exercises on the cardiovascular and respiratory systems of students].

The paper deals with the impact of physical classes at a higher educational establishment on the cardiovascular and respiratory systems of students. First- and second-year students who did physical exercises in accordance with the curriculum and fourth-year students who did not were followed up. Blood pressure and heart rate before and after exercise and the maximum oxygen consumption were used as parameters that characterized the state of the cardiovascular and respiratory systems. No physical exercises in third- and fourth-year students were shown to negatively affect their cardiorespiratory system. The current introduction of physical exercises at all courses of higher educational establishments is positively appreciated.

Adolescent↗
PubMed1984

Noninvasive determination of total respiratory system compliance in infants by the weighted-spirometer method.

The weighted-spirometer method for noninvasive determination of static total respiratory system compliance (Crs) was adapted for use in infants. Ten normal newborns and 5 infants with bronchopulmonary dysplasia (BPD) were studied. The newborns had a mean Crs of 3.8 ml/cm H2O. Their mean specific Crs was 1.13 ml/cm H2O/kg body weight and 0.075 ml/cm H2O/cm body length. These Crs values were similar to those reported by other investigators who used the Hering-Breuer airway occlusion technique. The infants with BPD, who were of the same weight, height, and postconception age as the normal newborns, had significantly (p less than 0.05) lower mean specific Crs (0.60 ml/cm H2O/kg body weight and 0.047 ml/cm H2O/cm body length) relative to the normal newborns. These data suggest that intrinsic changes in lung elastic characteristics may contribute to the reduced lung compliance of infants with BPD. The weighted-spirometer method for measuring Crs is a potential tool for the noninvasive study of the elastic properties of the respiratory system during infancy in health and disease.

Body Height↗
PubMed2000

Host defence mechanisms of the respiratory system.

From the moment of the first breath at the time of birth, the respiratory system must be protected from numerous insults from the environment. The way in which the airways are prepared for these insults is by an extraordinarily effective defence system. This defence system includes mechanical as well as biochemical processes that work in an integrated way to safeguard the lungs. The airways have an efficient, highly vigilant, non-inflammatory anti-microbial defence system, capable of dealing with a wide spectrum of microbes, and provide lifelong protection of these vital mucosal surfaces. The different aspects of this defence system of the airways are discussed. The effectiveness of the system must be improved, especially in children prone to frequent respiratory infections like cystic fibrosis. Future research must be focused on restoring the defect in the defence mechanism, but also in a more appropriate shield against pathogenic micro-organisms.

Bacterial Adhesion↗
PubMed2006

[A prospective cohort study on comparison of risk of death of respiratory system diseases between occupational dust exposure and smoking].

OBJECTIVE: To compare the effects of dust exposure and smoking on mortality of respiratory system diseases (RSD). METHODS: Based on the Guangzhou Occupational Health Surveillance Record System established between 1989 and 1992, 80,987 factory workers, aged 30 years old or older, occupationally exposed or not exposed to dusts, were included in a prospective cohort study. RESULTS: (1) The mean age of the cohort was 43.5. Most subjects were workers, had secondary education, and almost all were married. The dust exposure rate was 16.3%, the smoking rate 43.7% and the alcohol-drinking rate 33.5%. (2) The cohort was followed up for 8 years on average, but 35 people (0.04%) were lost for follow up. Among the 1593 deaths, 219 and 90 people died of lung cancer and non-cancer respiratory system diseases (NCRSD) respectively. (3) The adjusted relative risk (RR) of death of lung cancer for smokers, 3.32, was 2.2 times of that for dust exposed workers, 1.53, and the RR of death of NCRSD for dust exposed workers, 2.41, 1.28 times of that for smokers, 1.89, especially for silica dust-exposed workers, 5.72, 3.03 times of that for smokers. Dust exposure combined with smoking caused significantly higher RR of death of RSD. (4) In male, the death risks of RSD were increased with the amount of smoking per day and years of smoking. CONCLUSION: Occupational dust exposure and smoking may cause excessive lung cancer and NCRSD death with synergistic effects. Smoking has higher RR of Lung cancer death than dust exposure. However, the dust exposure contributes to higher RR of NCRSD death. There is a significant dose-effect relationship between smoking and the death risk of RSD.

Adult↗
PubMed1992

Variability of respiratory system compliance in mechanically ventilated infants.

We measured respiratory flow, volume by integrated flow, and airway pressure in four mechanically ventilated infants. Compliance of the respiratory system (Crs) was measured by the multiple occlusion method. Airway occlusion and release were achieved by a balloon in an occlusion valve between the endotracheal tube and a pneumotachometer, all connected in series with the respirator circuit. Values of Crs varied greatly due to changes in mean airway pressure (MAP). The Crs increased with the elevation of MAP on some occasions and decreased on others. Values of Crs also varied corresponding to different occlusion pressures for individual levels of MAP. Thus Crs changed continuously, even within a single respiratory cycle. The observed variability in Crs was explained by the following mechanism: a pressure-volume (P-V) loop of tidal ventilation moves its position within the pressure-volume diagram and changes shape due to variations of the ventilator settings. In some infants the lungs were ventilated in the range of the linear portion of the P-V diagram while in others they may have been ventilated on the flattened portion. Some patients had convex expiratory P-V curves even with low pressure swings during tidal ventilation.

Airway Resistance↗
PubMed1993

Inflation static pressure-volume curves of the total respiratory system determined without any instrumentation other than the mechanical ventilator.

OBJECTIVE: To assess the accuracy of static pressure-volume (PV) curves of the total respiratory system performed with the data directly obtained from the Servo 900 C vs. the data obtained from an external calibrated device. DESIGN: Performance of the PV curve by the method of Levy with simultaneous recording of data obtained from both systems. SETTING: The general ICU of Hospital de Sabadell. PATIENTS: Ten sedated and paralyzed patients ventilated in the control mode for acute respiratory failure were evaluated. INTERVENTIONS AND MEASUREMENTS: Inflation static PV curves were performed by the method of Levy. We simultaneously measured airway pressure and volume by means of calibrated pressure transducer and pneumotachograph and by the internal devices built in the ventilator Siemens Servo 900 C. Statistics were concordance analysis between the two methods and covariance analysis between derived curves. RESULTS: concordance analysis between both methods showed a 95% confidence interval of (+4%, -5%) in volume and (+2.2 cmH2O, -1.7 cmH2O) in pressure. Derived PV curves analyzed by MANOVA showed no significant differences whichever the method used within subject (p = 0.579). CONCLUSION: Inflation static pressure volume curves of the total respiratory system can be accurately performed with the data directly obtained from the Servo Ventilator 900 C without the need of any other external device.

Aged↗
PubMed1996

[Compensatory reactions of the rabbit respiratory system to hypoxic stimulation in hyperbaric conditions].

Two series of experiments were performed with awake rabbits to study ventilatory reactions of the respiratory system to hypoxic stimulus. Two types of tests included alternating exposure to hypoxic mixture with 14%, 12%, and 10% of O2 (for 10 min) and rebreathing (12% O2 + 4.5% CO2) with concurrent sampling of arterial blood for gas analysis. The experiments were performed under the atmospheric pressure and in the nitrogen-oxygen air at 0.6, 1.0, 1.3, 1.5, 2.0, and 3.0 MPa. Both of the tests disclosed a distinct reduction of pulmonary ventilation gain in hyperbaric conditions due to inhalation of a hypoxic mixture. In the experiment with alternating exposure to hypoxic mixtures the gain reduction was gradual and correlated with a pressure rise. During rebreathing, hypoxemia appeared as early as the first minutes of experiment. PaCO2 grew by the end of exposure and abrupt inhibition of the ventilatory reaction occurred even at 0.6 MPa. Sharp degrees of hypoxemia during rebreathing seemed to suppress the respiratory center to the extent at which the reaction to hypoxia became weaker rather than stronger and was manifested by a sudden attenuation. These results suggest that hyperbaric conditions reduce the ventilatory reaction to hypoxia and balancing potentials of the respiratory system, and impair the respiration controls.

Animals↗
PubMed2003

Spatial distribution of human respiratory system transfer impedance.

Transfer impedance (Ztr) of the respiratory system provides specific information on airways and tissues, but little is known about its spatial distribution in the different thoracoabdominal regions. To study Ztr distribution on the chest wall surface we analyzed five healthy subjects in the supine position by applying a sinusoidal forcing pressure (4, 8, and 12 Hz) at the mouth and measuring airway opening pressure and flow. Three-dimensional positions of 68 reflective markers placed on the chest wall over selected reference points were simultaneously measured by an optoelectronic motion analyzer. A subset of ten points placed on the midline were used to measure chest wall movements in the craniocaudal direction. While the motion of rib cage markers was synchronous, the abdominal markers demonstrated surface waves propagating caudally. The amplitude and phase of these waves were strongly dependent on position and frequency. We used a new method to measure total and local chest wall volume variations to compute the distribution of Ztr over the chest wall. Above 4 Hz we found that Ztr was inhomogeneously distributed and strongly dependent on position and frequency, mainly in the abdomen where the phase was often more more than 180 degrees with high values of modulus. For this reason, we conclude that above 8 Hz Ztr represents rib cage mechanics almost exclusively.

Abdomen↗
PubMed1996

Pathophysiology of the respiratory system related to anesthesia.

The pathophysiology of the respiratory system can be viewed by simply evaluating the status of a functional residual capacity (FRC). More specifically, patients with airways that are characterized as extremely compliant or "floppy" will have an increased FRC, which is the hallmark of chronic obstructive pulmonary disease. Patients with noncompliant, "stiff" lungs suffer from a form of restrictive disease with a resultant reduction in the FRC. Hence, the implications for anesthesia care focus on the FRC; that is, raising the FRC in the restrictive disease patient and normalizing or preventing further increase in the FRC in the patient with chronic obstructive pulmonary disease.

Anesthesia↗
PubMed1990

Structure and function of the respiratory system of the dystrophic hamster.

The BIO 14.6 dystrophic hamster has been used extensively over the past 30 years as an animal model in which to study the mechanisms responsible for the development of cardiomyopathy and skeletal muscle dysfunction associated with muscular dystrophy. More recently, structural and functional aspects of the respiratory system of this animal model have been investigated. This review summarizes our current knowledge of ventilation, lung morphometry and mechanics, the structure and function of the diaphragm, tracheal and pulmonary vascular smooth muscle, and pulmonary macrophages in the BIO 14.6 dystrophic hamster. We conclude that many aspects of the structure and function of the respiratory system of this hamster warrant further investigation, including the development of alveolar hypoventilation, the causes of pulmonary vascular hyporeactivity, and the potential contribution of abnormal pulmonary macrophages to the pathogenesis of life-threatening respiratory disease in muscular dystrophy.

Animals↗
PubMedDate not supplied

Role of serotonin in the regulation of respiratory system function.

Role of serotonin in the regulation of respiratory system function. Acta Physiol. Pol., 1978, 29 (2): 131--138. This study examined respiratory centre reflector excitability, the electrical activity of respiratory muscles, outer breathing, pH and arterial blood gas composition under conditions of experimentally induced serotonin excess or deficiency in 48 dogs. It was found that excess of serotonin in the animals leads a strenghthening of respiratory action in terms of increased respiratory centre bioelectrical excitability, muscular electrical activity and outer respiratory indices, such as frequence, volume and lung ventilation per min. In addition the pH of blood shifted to alkalic and oxygen tension of the blood increased while CO2 tension of the blood decreased.

Animals↗
PubMed2003

Nonlinear and frequency-dependent mechanical behavior of the mouse respiratory system.

The assessment of the mechanical properties of the respiratory system is typically done by oscillating flow into the lungs via the trachea, measuring the resulting pressure generated at the trachea, and relating the two signals to each other in terms of some suitable mathematical model. If the perturbing flow signal is broadband and not too large in amplitude, linear behavior is usually assumed and the input impedance calculated. Alternatively, some researchers have used flow signals that are narrow band but large in amplitude, and invoked nonlinear lumped-parameter models to account for the relationship between flow and pressure. There has been little attempt, however, to deal with respiratory data that are both broadband and reflective of system nonlinearities. In the present study, we collected such data from mice. To interpret these data, we first developed a time-domain approximation to a widely used model of respiratory input impedance. We then extended this model to include nonlinear resistive and elastic terms. We found that the nonlinear elastic term fit the data better than the linear model or the nonlinear resistance model when amplitudes were large. This model may be useful for detecting overinflation of the lung during mechanical ventilation.

Airway Resistance↗
PubMed1996

Respiratory system reactance as an indicator of the intrathoracic airway response to methacholine in children.

The upper airways may contribute to increases in airway resistance in response to a bronchial challenge, and thus decrease the specificity of such challenge tests to diagnose airway hyperresponsiveness when forced oscillation techniques are used to evaluate changes in respiratory system resistance (Rrs). A concomitent decrease in respiratory system reactance (Xrs) may indicate a change in the intrathoracic airways and/or lung parenchyma, provided that extrathoracic airway wall motion is prevented. To test the value of Xrs in the evaluation of bronchial hyperresponsiveness, we studied the respiratory impedance response to methacholine in 38 children with a history of asthma (aged 6-14.5 years), and compared the results to changes in the forced expiratory volume in one second (FEV1). Rrs and Xrs were measured by the forced oscillation technique with pseudorandom (11 subjects) or sinusoidal (27 subjects) pressure variations applied around the child's head to minimize upper airway wall motion. Changes in Rrs and in Xrs at 12 Hz (Rrs12, Xrs 12) correlated significantly with changes in FEV1 (P < 0.005). A decrease in FEV1 > or = 20% was observed in 23 subjects. When these 23 subjects were compared with the 15 children who did not show significant changes in FEV1, the responding group had larger mean +/- SEM changes in Rrs (116.0 +/- 13.2% vs 60.4 +/- 11.4%, P < 0.006) and in Xrs (-2.1 +/- 0.4 hPa.s/L vs -0.9 +/- 0.3 hPa.s/L, P < 0.03) than the nonresponders. The receiver operating characteristics (ROC) curve analysis was used to assess the diagnostic value, i.e., specificity and sensitivity, of different levels of change in Rrs and Xrs, with reference to FEV1. The overall incidence of false results was similar for Rrs and Xrs. The optimum diagnostic value for Rrs was a 70% increase, which corresponded to a sensitivity of 87% and a specificity of 67%. For Xrs the optimum decision level was -1 hPa.s/L, corresponding to a sensitivity of 70% and a specificity of 80%. It is concluded that Xrs may improve the specificity of the forced oscillation technique in interpreting the airway response to methacholine. This may be of particular interest in young children unable to perform forced expirations.

Adolescent↗
PubMed1982

[Dynamic functional changes in the respiratory system in acquired heart defects].

One hundred forty eight patients were examined, 56 of them followed up dynamically. The following indices were determined--external respiration, diffuse capacity of lungs and its components, acid-base state and blood gases, functional and true intrapulmonary shunts, etc. The results revealed that the dynamic functional disorders in respiratory system in the acquired valvular diseases are reversible, to a great extent, after the application of a complex therapy. Most significant is the dynamics of the recovery in stage IIA of cardiac insufficiency and the changes in DLCO, SS and DM, VC, MRV, RQ, DS%RC. The disturbed respiratory function in stage I of cardiac insufficiency is almost completely restored, whereas in stage IIB--the recovery processes are less manifested, conditioned by the reduced compensatory mechanism and the advancing of irreversible pathomorphological changes. The changes in DLCO, SS are the most sensitive ones, being the earliest to manifest, even before the manifestation of the clinical symptoms and could aid the early functional diagnostics of the acquired valvular defects. The dynamic follow up of the functional changes in the respiratory system enables us to assess more thoroughly the results from the treatment, evolution and prognosis of the acquired valvular diseases.

Acid-Base Equilibrium↗
PubMed1999

Compliance of the respiratory system as a predictor for successful extubation in very-low-birth-weight infants recovering from respiratory distress syndrome.

OBJECTIVE: To develop additional criteria to predict for successful extubation of very-low-birth-weight infants recovering from respiratory distress syndrome. DESIGN: Prospective study. SETTING: Neonatal intensive care unit at a university teaching hospital. INTERVENTIONS: Infants ready for extubation according to clinical, ventilatory and blood gas criteria were studied. Before extubation, tidal volume (Vt), minute ventilation, respiratory rate/Vt and mean inspiratory flow were measured during two different ventilatory settings: (i) during intermittent mandatory ventilation (IMV); and (ii) while breathing spontaneously with endotracheal continuous positive airway pressure (CPAP). Tidal volume was obtained through electronically integrated flow measured by a hot-wire anemometer. Total respiratory compliance (Crs) was determined during IMV and was derived from the formula Vt/PIP-PEEP, where the difference between peak inspiratory pressure (PIP) and positive end-expiratory pressure (PEEP) represented the ventilator inflation pressure. MEASUREMENTS AND MAIN RESULTS: Each of 49 infants was studied once before extubation. 33 infants (67%) were successfully extubated and 16 (32.6%) required reintubation. Infants in the success and failure groups were matched for gestation, post-conceptional age, study weight and methylxanthine therapy at the time of study. Successful extubation was associated with a higher mean absolute Crs value (ml/cm H2O) specific Crs value (standardised for body length; ml/cm H2O/cm) compared with infants in whom extubation failed (0.67 v. 0.46; P = 0.01 and 0.018 v. 0.014; P = 0.03, respectively). Analysis of ROC curves detected thresholds for Crs (0.5 ml/cm H2O) and Vt (7 ml) for predicting successful extubation. An absolute Crs value 0.5 ml/cm H2O or more improved the likelihood of successful extubation when compared with clinical/ventilator and blood gas criteria. The likelihood of successful extubation was 81% if the Crs value was > or = 0.5 ml/cm H2O. A tidal volume of 7 ml or more was less sensitive in contributing to successful extubation (sensitivity 69%). The major causes for extubation failure included atelectasis (diffuse and/or localised) and the presence of a patent ductus arteriosus. CONCLUSIONS: In addition to following very precise ventilatory criteria for extubation, we found that bedside measurement of total respiratory system compliance added to the likelihood of extubation success in infants recovering from respiratory distress syndrome. Prospective studies are needed to validate the findings of this study.

Aminophylline↗
PubMed1991

Characterization of glycoconjugates in developing rat respiratory system by means of conventional and lectin histochemistry.

The glycoconjugates of the respiratory system of rats from 15 days of gestation through the adult period have been characterized by means of both conventional and lectin histochemistry. The main changes occurred at 20-21 days of gestation immediately before birth. An increase of acidic groups in the glycoproteins of the lung and airway epithelium was observed by conventional mucin histochemistry. The combined use of neuraminidase digestion and lectin histochemistry demonstrated an increase of sialic acid residues at the terminal position of the glucidic moieties of the glycoproteins. The sialic acid residues were linked alpha (2-3, 6) to D-galactose (beta 1-3)-N-acetylgalactosamine, thus masking the PNA-reactivity detected on the luminal surface of Clara cells and pneumonocytes before birth. In the adult period, alpha-L-fucose residues, detected by UEA-I, were localized in the glycoproteins contained in goblet cells and periciliary layer of the rat airway epithelium. The modifications observed in the lung of developing rats are similar to those previously described in human fetal and neonatal lungs. This suggests that the rat represents a useful model to study the glycoprotein synthesis during lung development.

Animals↗