The influence of the bronchodilatation test on the duration of forced expiratory tracheal noises in young men

The diagnostic efficiency of estimating the duration of forced expiratory noises under the conditions of bronchial obstruction has been shown. The objective of this study was to analyze the response of the forced expiratory noise duration to the bronchodilatation test with the β₂-agonist in the age- and genderhomogenous group of healthy volunteers and bronchial asthma patients selected as a model of variable bronchial obstruction. Two hundred and sixty young men (16–25 years old) were examined. It was shown that the prevailing type of response in bronchial asthma patients with spirometry confirmed bronchial obstruction was shortened forced expiratory noises. Furthermore, the degree of the shortening considerably depended on the severity of the background bronchial obstruction. The absence of a statistically significant response of the forced expiratory noise duration dominated among healthy volunteers (nonsmokers as well as smokers) and bronchial asthma patients without a spirometry confirmed bronchial obstruction. However, the shortened response occurred much more frequently in bronchial asthma patients than in healthy volunteers. The high specificity (86%) of the response as shortened forced expiratory noises to the β₂-agonist may be useful for diagnostics.     

Regression simulation of the dependence of forced expiratory tracheal noises duration on human respiratory system biomechanical parameters

BACKGROUND: Estimating the duration of forced exhalation tracheal noises shows promise for recognizing bronchial obstruction. OBJECTIVE: Experimental simulation of an influence of biomechanical parameters on the duration of normal forced exhalation tracheal noises. METHOD AND MATERIALS: Thirty-two healthy non-smoking men aged 16-22 years were examined. The duration of noises, the parameters of computer spirometry, and the maximum static expiratory pressure are recorded. These data were analyzed by means of multiple linear regression simulation for logarithms of the elements of the proportionality relation obtained with the use of a one-component biomechanical model of forced exhalation and a linearized approximation of flow-volume curve. RESULTS: Dependence between duration of the forced expiratory noises recorded on human trachea and the product of forced volume capacity (in power of 1.05 +/- 0.27), maximum static expiratory pressure (in power of 0.46 +/- 0.23), equivalent expiratory resistance in the stage of functional expiratory stenosis (in power of 0.72 +/- 0.15 in healthy is an estimate of the equivalent expiratory resistance of human bronchial tree in the functional expiratory stenosis phase, whereas in patients with bronchial obstruction it is supposed to take into account an excess of noise generation time compared with the time predicted from normal individual value of this resistance.     

Comprehensive assessment of the hemostasis system in the participants of the Mars-500 experiment

Hemostasis has been studied in the course of long-term (520 days) isolation in hermetic chamber. Measured parameters included activated partial thromboplastin time (APTT), international normalized ratio (INR), thrombin time (ТT); concentrations of fibrinogen (FBG), plasminogen (PG), Willebrand factor (WF), tissue factor pathway inhibitor (TFPI), tissue plasminogen activator (TPA), and thrombomodulin (ТМ); activities of the coagulation cascade factors II, V, VII, X, VIII, IX, XI, and XII, antithrombin III (ATIII), protein С (PC), С1-inhibitor (С1), α₂-antiplasmin (АP), TPA and TFPI. The investigation revealed a diversity of changes in plasma FBG concentration, slower blood coagulation in the intrinsic pathway and in final stage, and a relative rise in the activities of ATIII and PC-inhibited factors. The remaining parameters exhibited different trends.     

Pattern of diaphragmatic activity during forced expiratory vital capacity

We measured transdiaphragmatic pressure (Pdi) during forced expiratory vital capacity (FVC) maneuvers in 13 normal subjects and electromyographic activity of the diaphragm (edi) in 8 of these subjects. In all subjects, Pdi increased at the initiation of the FVC. In most, this increase lasted 30--50 ms and reached levels well above the Pdi observed at total lung capacity (TLC). After the initial transient increase, approximately half of the subjects demonstrated a substantial fall in Pdi to values near the relaxation level in the mid-vital capacity (VC) volume range, while half showed a second large increase in Pdi in this volume range. Seven of eight subjects tested showed a rapid decrease in Edi at the onset of the FVC, reaching a minimum in 30--50 ms. After this initial transient decrease, Edi increased in six subjects in the mid-VC volume range, in association with secondary rises in Pdi. In two subjects, Edi remained low throughout the remainder of the FVC, and Pdi in the mid VC range was generally lower. These results are consistent with the conclusion that the diaphragm is neither electromyographically silent nor mechanically unimportant during the FVC. Changes in abdominothoracic configuration, superimposed upon "antagonistic" activity of the diaphragm, result in substantial reductions in pleural (esophageal) pressure that may influence regional lung emptying during the FVC.     

Estimation of tracheal sound intensity during forced expiration

The tracheal sounds during forced expiration were studied using the mathematical model of forced expiration. It has been shown that separated flow in the region of dynamic constriction of the trachea during forced expiration may cause the generation of tracheal sounds.     

Partial forced expiratory flow-volume curves in young children during ketamine anesthesia

Maximal flows at functional residual capacity (VmaxFRC) from partial forced expiratory flow-volume (PEFV) curves were obtained in 14 normal preschool children (8 boys, 6 girls) of average age 44 mo, under general anesthesia before elective surgery. PEFV curves were generated from end inspiration by rapid compression of the chest wall with an inflatable jacket. VmaxFRC, expressed in milliliter per second, correlated linearly with height, weight, age, and FRC in milliliter and milliliters per kilogram. The best correlation of VmaxFRC (ml/s) was to height to the power of 2.47, which agrees with the results predicted by wave-speed theory. Mean FRC-corrected VmaxFRC was 2.42 +/- 0.50 (SD) FRC's/s with no significant difference between boys (2.35 FRC's/s) and girls (2.51 FRC's/s). There was no correlation between lung-size corrected VmaxFRC and height, weight, or age, but it tended to decrease with increasing FRC. The intersubject variability for VmaxFRC was reduced by normalizing for FRC, and was significantly better than that reported for awake children. This can be attributed to the greater control over volume history and more reliable maximal flow generation during anesthesia. The intrasubject coefficient of variation (CV) for VmaxFRC was 12.2%, and the intersubject CV was 20.0%. The difference may represent the variability due to dysanapsis. It is concluded that dysanapsis is not a prominent factor in children of this age group. In addition, the similarity of the regression equation for VmaxFRC vs. height to that of FRC vs. height supports the concept of equidimensional growth of the airways and lung parenchyma.     

Evaluation of the efficiency of interpersonal interactions in a long-term isolation experiment

A computer-aided version of the Homeostat test was used to study the changes in the efficiency of cooperative fulfillment of homeostatic tasks in the course of long-term isolation in four ground-based experiments. A mathematical equation was derived to describe the dependence studied. The individual contributions of all operators into the efficiency of group activity in cooperatively fulfilling homeostatic tasks were compared at the final stage of the isolation.     

Density dependence of maximal expiratory flow before and during tracheal constriction in dogs

The effect of carbachol-induced central bronchoconstriction on density dependence of maximal expiratory flow (MEF) was assessed in five dogs. MEFs were measured on air and an 80% He-20% O2 mixture before and after local application of carbachol to the trachea. Airway pressures were measured using a pitot-static probe, from which central airway areas were estimated. At lower concentrations of carbachol the flow-limiting site remained in the trachea over most of the vital capacity (VC), and tracheal area and compliance decreased in all five dogs. In four dogs, decreases in choke point area predominated and produced decreases in flows. In one dog the increase in airway "stiffness" apparently offset the fall in area to account for an increase in MEF. Density dependence measured as the ratio of MEF on HeO2 to MEF on air at 50% of VC increased in all five dogs. Increases in density dependence appeared to be related to increases in airway stiffness at the choke point rather than decreases in gas-related airway pressure differences. Lower concentrations produced a localized decrease in tracheal area and extended the plateau of the flow-volume curve to lower lung volumes. Higher concentrations caused further reductions in tracheal area and greater longitudinal extension of bronchoconstriction, resulting in upstream movement of the site of flow limitation at higher lung volumes. Density dependence increased if the flow-limiting sites remained in the trachea at mid-VC but fell if the flow-limiting site had moved upstream by that volume.     

Acoustic and spirometry parameters of forced expiratory sounds during a five-day dry immersion

The dynamic studies of the parameters of forced expiration under the conditions of a five-day dry immersion involved seven healthy male subjects aged 20 to 25 years. During forced expiration, spirometry tests were performed simultaneously with tracheal sounds being recorded by a microphone. A number of parameters, including the acoustic duration of the forced-expiration tracheal sounds, the lungs’ forced vital capacity, the 1-s forced expiration volume, the peak expiratory flow, and time of achieving the peak expiratory flow, were recorded before dry immersion, on days 1 and 4 of immersion, and the next day after the termination of immersion. There was a significant decrease (by 8.4%) in the peak expiratory flow on day 1 of immersion; however, by day 4 of immersion, the peak expiratory flow increased by 8.9%, reaching its baseline values. The lungs’ forced vital capacity and the forced expiration volume during 1 second, on the average, did not change throughout the experiment. There was a significant increase (by 17%) in the duration of the forced expiration tracheal sounds after the immersion, which suggests an increase in respiratory resistance and needs further studies. A moderate negative correlation between the duration of the forced expiration tracheal sounds and Gensler’s index (r = ?0.63) was found, whereas the correlation with other spirometry parameters was weak or absent.     

Reflex control of expiratory duration in newborn infants

We investigated the effect on expiratory duration (TE) of application of graded resistive and elastic loads and total airway occlusions to single expirations in 9 full-term healthy infants studied on the 2nd or 3rd day of life. The infants breathed through a face mask and pneumotachograph, and flow, volume, airway pressure, and diaphragm electromyogram (EMG) were recorded. Loads were applied to the expiratory outlet of a two-way respiratory valve using a manifold system. Application of all loads resulted in expired volumes (VE) decreased from control (P less than 0.05), and changes were progressive with increasing loads. As VE became smaller, end-expiratory volume (EEV) became greater. TE, measured either from the pattern of airflow or airway pressure, or from diaphragm EMG activity, progressively increased with increasing loads and was greatest with total occlusions (P less than 0.05, compared with control). Resistive loading resulted in a greater accumulated VE history than elastic loading to the same EEV. For equivalent changes in EEV, TE was more prolonged with resistive than with elastic loading. Expiratory loading did not change the inspiratory duration determined from the diaphragm EMG activity of the breath immediately following each loaded expiration. These findings in infants are consistent with an integrative neural mechanism that modulates TE in response to the accumulated VE history, including both EEV and rate of lung deflation.     

Effect of compression pressure on forced expiratory flow in infants

The effect of the force of compression on expiratory flow was evaluated in 19 infants (2-13 mo of age) with respiratory illnesses of varying severity. An inflatable cuff was used to compress the chest and abdomen. Expiratory flow and volume, airway occlusion pressure, cuff pressure (Pc), and functional residual capacity were measured. Transmission of pressure from cuff to pleural space was assessed by a noninvasive occlusion technique. Close correlations (P less than 0.001) were found between Pc and the change in pleural pressure with cuff inflation (delta Ppl,c). Pressure transmission was found to vary between two cuffs of different design and between infants. Several forced expirations were then performed on each infant at various levels of delta Ppl,c. Infants with low maximal expiratory flows at low lung volumes required relatively gentle compression to achieve flow limitation and showed decreased flow for firmer compressions. Flow-volume curves in each infant tended to become more concave as delta Ppl,c increased. These findings underline the importance of knowledge of delta Ppl,c in interpreting expiratory flow-volume curves in infants.     

Nutritional Status in the Experiment with 105-Day Isolation as the First Phase of the Mars-500 Project

In a 105-day experiment simulating crew life in a interplanetary spaceship, shifts in the nutritional status were assessed in six volunteersthat differed in the body weight index, basal metabolic rate, attitude to the proposed diet, physical exercise, and workload. The results of the investigation showed that hard physical work under the conditions of the experiment led to the formation of the nutritional status against the background of more intensive basal metabolism, elevated metabolism of carbohydrates and lipids, and their increased mobilization from fat depot. Food ration, though it was sufficient to sustain health and fairly high calorie, did not fully meet individual taste preferences of some crewmembers and energy needs for physical activities. Under these conditions, heavy workloads required mobilization of lipids from fat depot and reducedthe hepatic detoxification and metabolic capacities. Self-limitation of eating protein-rich desserts led to a relative deficiency of protein intake. These changes in the diet were the reason why four out of six test subjects reduced their basal metabolism and lost body mass. The recovery of metabolism and slowdown of the body weight loss were achieved under these conditions by supplementing meals with digestible proteincontaining products.     

Interpersonal Interaction under the Conditions of High Autonomy in Interplanetary Mission Simulation (Mars-500 Experiment)

This paper discusses the influence of the social status and psychological stability of individuals on their communicative behavior in space flight on the basis of retrospective analysis of the findings of the Mars-500 experiment, in which six participants were isolated for a period of simulating a long-term exploration mission. Data were obtained using both classic social-psychological methods and observation of video recorded behavior. Communicative behavior of the crew members was dependent on the level of individual anxiety and social status in the isolated small group.     

Model of forced expiratory flows and airway geometry in infants.

Early measurements of autopsied lungs from infants, children, and adults suggested that the ratio of peripheral to central airway resistance was higher in infants than older children and adults. Recent measurements of forced expiration suggest that infants have high flows relative to lung volume. We employed a computational model of forced expiratory flow along with physiological and anatomic data to evaluate whether the infant lung is a uniformly scaled-down version of the adult lung. First, we uniformly scaled an existing computational model of adult forced expiration to estimate forced expiratory flows (FEF) and density dependence for an 18-mo-old infant. The values obtained for FEF and density dependence were significantly lower than those reported for healthy 18-mo-old infants. Next, we modified the model for the infant lung to reproduce standard indexes of expiratory flow [forced expiratory volume in 0.5 s (FEV(0.5)), FEFs after exhalation of 50 and 75% forced vital capacity, FEF between 25 and 75% expired volume] for this age group. The airway sizes obtained for the infant lung model that produced accurate physiological measurements were similar to anatomic data available for this age and larger than those in the scaled model. Our findings indicate that the airways in the infant lung model differ from those in the scaled model, i.e., middle and peripheral airway sizes are larger than result from uniform downscaling of the adult lung model. We show that the infant lung model can be made to reproduce individual flow-volume curves by adjusting lumen area generation by generation.