External Gas Exchange Research Articles

Clinical effectiveness of phospholipids in patients with restrictive respiratory failure due to lung tissue inflammation

Objective — to analyze the clinical effectiveness use of phosphatidylcholine liposomes in the treatment of patients with restrictive respiratory failure caused by acute pneumonia and pneumonia with a prolonged course.
 Materials and methods. A prospective cohort study of 68 people was conducted on the basis of the pulmonology department of the Kirovohrad Regional Hospital of the Kirovohrad Regional State in 2020—2021. The people were divided into two groups: I (n = 20) — control group, II (n = 48) — experimental group. They were composed of men aged 25 to 40 years. The first group consisted of healthy individuals who underwent a preventive examination. The second group included patients who, in addition to the traditional treatment of pneumonia, were treated with phospholipids in liposomal form. The drug was used by inhalation according to the instructions. In the course of the experiment, the volume-time indicators of external respiration and gas exchange of the body were studied in dynamics.
 Results and discussion. The introduction of phospholipids in liposomal form had a positive effect on the restoration of the function of external respiration from the 5th day of treatment of the disease. This is evidenced by the gradual normalization of breathing rate and respiratory volume. It was shown that the ratio of alveolar ventilation and minute respiratory volume was significantly lower and ranged from 60.3 to 72.7 % (with a control value of 72.2 to 77.4 %). Oxygen consumption increased by approximately 76 % on the 5th day of the disease, which indicates a pronounced increase in the level of oxidative metabolism in the body during this pathological process. Recovery could be observed due to optimization of the body’s oxygen supply. Regarding carbon dioxide release, this indicator was almost 2.3 times higher than the control values ​​on the 5th day of the disease. This contributes to the development of metabolic acidosis, which in turn leads to respiratory alkalosis. Against the background of phosphatidylcholine liposomes treatment, this indicator gradually decreased and had a tendency to approach control values ​​a month after treatment (0.216 ± ± 0.042) l/min). Another of the studied indicators is the dead breathing space. According to this indicator, the efficiency of external breathing also increased. The minute volume of blood flow in healthy individuals was (6.5 ± 0.7). During the disease, it decreased to (4.7 ± 0.8) with gradual recovery, starting from the 10th day of treatment with phospholipids. There is also a decrease in the oxygen saturation of the arterial blood and a decrease in the use of oxygen, which can be judged by the characteristics of the venous blood; at the same time, the determined oxygen consumption increases due to hyperventilation. One month after the treatment, these indicators were no longer significantly different from the control values. A similar trend is noted in the analysis of oxygen tension in arterial and venous blood, with a gradual normalization of indicators against the background of the use of phosphatidylcholine liposomes. The determination of the alveolar-arterial difference in oxygen showed an increase in the indicator in the experimental group compared to the control group. Most of the indicators we studied contributed to the decrease in oxygen, thus increasing the efficiency of external respiration.
 Conclusions. Phosphatidylcholine liposomes are an effective means of complex therapy of pneumonia. The drug has a normalizing effect on the level of energy metabolism in the body and normalizes oxygen consumption, contributing to a faster recovery of the optimal intensity of metabolic processes.

Compensatory mechanisms of adaptation of the cardiorespiratory system of athletes of different ages

The mechanism of external respiration and gas exchange in sportsmen ECG stress test are studied. It is established that adaptation of the cardiorespiratory , system to the increasing load in groups of sportsmen of different age is going through various ways. In groups of teenagers and adults aged 3660 it occurs through pulmonary ventilation, in sportsmen aged 2236 it occurs as a result of the increase of the oxygen use ratio, and in groups of youths by the activation of gasotransportation system

Анализ показателей газообмена организма в высотном полете на основе статической модели респираторной системы

The purpose of the research was to analyze the dynamics of indicators of human gas exchange in high-altitude flight on the basis of a static model of the respiratory system of the body. First, we developed the structure of this model and an algorithm for calculating the gas exchange of the body. Next, we analyzed changes in indicators of the function of external respiration and gas exchange, and clarified the quantitative parameters that determine the nature of the relationships between the components of gas exchange. Finally, we carried out a computational experiment to simulate ascent to a height. The results of the analysis of the calculations showed that when a person rises to a height with a drop in pressure, tidal volumes change the volume of the alveolar space decreases and the dead space increases in the ratio from 4.7 to 0.7. An uncompensated respiratory alkalosis develops, leading to a violation of the acid-base reactions of the body.

Mechanical circulatory support: balancing bleeding and clotting in high-risk patients.

Mechanical circulatory support (MCS) provides a bridge to heart transplant in children and adults with life-threatening heart failure and sustains patients ineligible for transplant. Extracorporeal membrane oxygenation (ECMO) provides temporary support for patients in cardiac or pulmonary failure through external gas exchange and continuous flow of blood. Because the median time to heart transplant exceeds event-free time on ECMO, pulsatile left ventricular assist devices (LVADs) are used to support infants and children. Continuous flow LVADs are preferred in adolescents and adults due to increased pump durability and improved overall survival. The shear stress created by the mechanical pumps cause changes in the hematologic system; acquired von Willebrand syndrome occurs in almost all patients treated with MCS. Despite the improvements in survival, major bleeding occurs in one-third of patients with a LVAD and ischemic stroke and LVAD thrombosis can affect 12% of adults and 29% of children. An antithrombotic strategy to mitigate LVAD bleeding and thrombotic complications has been tested in a randomized trial in children, but intensity of antithrombotic therapy in adults varies widely. Consensus guidelines for antithrombotic therapy during ECMO were created due to significant differences in management across centers. Because of the high risk for both bleeding and thrombotic complications, experts in hemostasis can significantly impact care of patients requiring mechanical circulatory support and are a necessary part of the management team.

Dynamics of seasonal parameters of external respiration and gas exchange in the population of Northeast Russia

Within the framework of the Mars-500 project, a monthly monitoring of several morphofunctional parameters was performed over the period of 18 months in 19 Caucasoid volunteers born in the Magadan oblast. Somatometric parameters and functional parameters of the respiratory and cardiovascular system were determined in volunteers using standard procedures. It was established that the highest strain in the functioning of these body systems is recorded in winter. However, during summer, both systolic and diastolic arterial pressure was also higher than the respective parameters in people living in midland and European northeast Russia, which may indicate a significant effect of the natural and climatic seasonal factors of Magadan oblast on volunteers throughout the year.

Directed Epicardial Assistance in Ischemic Cardiomyopathy: Flow and Function Using Cardiac Magnetic Resonance Imaging

Heart failure after myocardial infarction (MI) is a result of increased myocardial workload, adverse left ventricular (LV) geometric remodeling, and less efficient LV fluid movement. In this study we utilize cardiac magnetic resonance imaging to evaluate ventricular function and flow after placement of a novel directed epicardial assist device. Five swine underwent posterolateral MI and were allowed to remodel for 12 weeks. An inflatable bladder was positioned centrally within the infarct and secured with mesh. The device was connected to an external gas exchange pump, which inflated and deflated in synchrony with the cardiac cycle. Animals then underwent cardiac magnetic resonance imaging during active epicardial assistance and with no assistance. Active epicardial assistance of the infarct showed immediate improvement in LV function and intraventricular flow. Ejection fraction significantly improved from 26.0% ± 4.9% to 37.3% ± 4.5% (p < 0.01). End-systolic volume (85.5 ± 12.7 mL versus 70.1 ± 11.9 mL, p < 0.01) and stroke volume (28.5 ± 4.4 mL versus 39.9 ± 3.1 mL, p = 0.03) were also improved with assistance. End-diastolic volume and regurgitant fraction did not change with treatment. Regional LV flow improved both qualitatively and quantitatively during assistance. Unassisted infarct regional flow showed highly discoordinate blood movement with very slow egress from the posterolateral wall. Large areas of stagnant flow were also identified. With assistance, posterolateral wall blood velocities improved significantly during both systole (26.4% ± 3.2% versus 12.6% ± 1.2% maximum velocity; p < 0.001) and diastole (54.3% ± 9.3% versus 24.2% ± 2.5% maximum velocity; p < 0.01). Directed epicardial assistance can improve LV function and flow in ischemic cardiomyopathy. This novel device may provide a valuable alternative to currently available heart failure therapies.

Comparative analysis of gas exchange and cardiorespiratory system responses of swimmers and skiers to increasing normobaric hypoxia and physical load

Qualification-comparable groups of young men engaged in cyclic kinds of sports were tested using a stepwise increasing load on a bicycle ergometer and 25-min exponentially increasing normobaric hypoxia to a final oxygen concentration of 10%. Skiers, who had the greatest values of maximal oxygen consumption during muscular work, showed relaxed cardiorespiratory reactions and a greater decrease in hemoglobin saturation with oxygen in hypoxia. Swimmers, whose ventilatory function in the course of trainings was restricted, developed preadaptation to hypoxia, with changes in external respiration and gas exchange functions, which allowed better saturation of blood with oxygen in lungs during hypoxia. The joint assessment of the aerobic capacity during physical work and physiological responses to hypoxia showed a direct correlation between the individual maximal oxygen consumption and the rate of decrease in the blood hemoglobin saturation in increasing hypoxia, which may be promising for assessing the functional state of athletes and its correction during training.

Сравнительный анализ реакций газообмена и кардиореспираторной системы пловцов и лыжников на нарастающую нормобарическую гипоксию и физическую нагрузку

Qualification comparable groups of young men engaged in cyclic kinds of sports were tested with stepwise accruing loads on bicycle ergometer and 25-minute exponential increasing normobaric hypoxia to final concentration of 10% oxygen. Group of skiers, having the greatest values of the maximal oxygen consumption at muscular work, show the relaxed cardiorespiratory reactions and more falling of blood oxygen in the hypoxia. The swimmers, having restrictions of ventilatory function in the course of trainings, form preadaptation to hypoxia with changes of external respiration and gas exchange functions that allows at hypoxia to better oxygen sate the blood in lungs. The joint assessment of aerobic capacity at physical work and physiological reactions to hypoxia shows the direct relation between individual maximal oxygen consumption and the descent rate of blood oxygen saturation at accruing hypoxia that can be useful at an assessment of a sportsman functional state and its correction at training processes.

Hypoxia-induced compression in the tracheal system of the tobacco hornworm caterpillar,Manduca sextaL.

Abdominal pumping in caterpillars has only been documented during molting. Using synchrotron X-ray imaging in conjunction with high-speed flow-through respirometry, we show that Manduca sexta caterpillars cyclically contract their bodies in response to hypoxia, resulting in significant compressions of the tracheal system. Compression of tracheae induced by abdominal pumping drives external gas exchange, as evidenced by the high correlation between CO2 emission peaks and body movements. During abdominal pumping, both the compression frequency and fractional change in diameter of tracheae increased with body mass. However, abdominal pumping and tracheal compression were only observed in larger, older caterpillars (>0.2 g body mass), suggesting that this hypoxic response increases during ontogeny. The diameters of major tracheae in the thorax increased isometrically with body mass. However, tracheae in the head did not scale with mass, suggesting that there is a large safety margin for oxygen delivery in the head in the youngest animals. Together, these results highlight the need for more studies of tracheal system scaling and suggest that patterns of tracheal investment vary regionally in the body.

Functional reaction of the human body to different ways of respiration regulation

Reactions of the body to different ways of regulation of respiration, i.e., through the elastic resistance to respiratory movements and external dead space volume, as well as voluntary hyper- and hypoventilation, were studied. An increased elastic resistance to respiratory movements was established to create conditions for intense loading of respiratory musculature and to determine an increased in oxygen consumption. An increase in the external dead space produces a marked complex reaction of the body to the hypoxichypercapnic content of the inhaled gas mixture, causing hyperventilation and heightened work of the respiratory musculature and stimulating metabolism. Voluntary hyperventilation during muscular effort leads to a state of relative hypocapnia, gross loss of efficiency, and economic external respiration and gas exchange. Voluntary hypoventilation in the course of muscular effort brings about marked shifts in gas homeostasis towards alveolar hypoxia and hypercapnia. A concurrent increase in the efficiency and economy of external respiration and gas exchange is observed.

Tolerance of chufa (Cyperus esculentus L.) plants, representing the higher plant compartment in bioregenerative life support systems, to super-optimal air temperatures

Plants intended to be included in the photosynthesizing compartment of the bioregenerative life support system (BLSS) need to be studied in terms of both their production parameters under optimal conditions and their tolerance to stress factors that might be caused by emergency situations. The purpose of this study was to investigate tolerance of chufa (Cyperus esculentus L.) plants to the super-optimal air temperature of 45±1°C as dependent upon PAR (photosynthetically active radiation) intensity and the duration of the exposure to the stress factor. Chufa plants were grown hydroponically, on expanded clay, under artificial light. The nutrient solution was Knop’s mineral medium. Until the plants were 30days old, they had been grown at 690μmolm−2s−1 PAR and air temperature 25°C. Thirty-day-old plants were exposed to the temperature 45°C for 6h, 20h, and 44h at PAR intensities 690μmolm−2s−1 and 1150μmolm−2s−1. The exposure to the damaging air temperature for 44h at 690μmolm−2s−1 PAR caused irreversible damage to PSA, resulting in leaf mortality. In chufa plants exposed to heat shock treatment at 690μmolm−2s−1 PAR for 6h and 20h, respiration exceeded photosynthesis, and CO2 release in the light was recorded. Functional activity of photosynthetic apparatus, estimated from parameters of pulse-modulated chlorophyll fluorescence in Photosystem 2 (PS 2), decreased 40% to 50%. After the exposure to the stress factor was finished, functional activity of PSA recovered its initial values, and apparent photosynthesis (Papparent) rate after a 20-h exposure to the stress factor was 2.6 times lower than before the elevation of the temperature. During the first hours of plant exposure to the temperature 45°C at 1150μmolm−2s−1 PAR, respiration rate was higher than photosynthesis rate, but after 3–4h of the exposure, photosynthetic processes exceeded oxidative ones and CO2 absorption in the light was recorded. At the end of the 6-h exposure, Papparent rate was close to that recorded prior to the exposure, and no significant changes were observed in the functional activity of PSA. At the end of the 20-h exposure, Papparent rate was close to its initial value, but certain parameters of the functional activity of PSA decreased 25% vs. their initial values. During the repair period, the parameters of external gas exchange recovered their initial values, and parameters of pulse-modulated chlorophyll fluorescence were 20–30% higher than their initial values. Thus, exposure of chufa plants to the damaging temperature of the air for 20h did not cause any irreversible damage to the photosynthetic apparatus of plants at either 690μmolm−2s−1 or 1150μmolm−2s−1 PAR, and higher PAR intensity during the heat shock treatment enhanced heat tolerance of the plants.

Hypoxia‐induced compression of the tracheal system in the caterpillar, Manduca sexta

Abdominal pumping in caterpillars has only been documented during molting. Here, with synchrotron x‐ray imaging and high‐speed flow‐through respirometry, we show that Manduca sexta caterpillars contract their bodies in response to hypoxia, which results in significant compression of the tracheal system. Tracheal compression induced by abdominal contraction appears to be the driving force for external gas exchange, as evidenced by the high correlation between CO2 emission peaks and external body movements. Both frequency and diameter of tracheal compression increased with body mass as caterpillars increased in age. However, abdominal pumping was only observed in larger, older caterpillars (&gt; 0.2 g body mass), suggesting that the hypoxia response varies with ontogeny. As insects increased in size, the fraction of tracheal system structures in the head increased, but not as much as would be predicted based on geometric scaling. The fraction of the body occupied by tracheae in the prothorax and last abdominal segment remain constant throughout ontogeny. Furthermore, diameter of major tracheae either do not vary with body mass or do not increase as much as expected, suggesting that trade‐offs between non‐respiratory structures result in smaller tracheae than would be expected based on geometric scaling. (Supported by NSF, NIH‐NCRR and US DOE)

Counterpoint: In health and in a normoxic environment, V̇o2 max is not limited primarily by cardiac output and locomotor muscle blood flow

Counterpoint: In health and in a normoxic environment, V̇<scp>o</scp>_{2 max} is not limited primarily by cardiac output and locomotor muscle blood flow

Leg Heating and Cooling Influences Running Stride Parameters but not Running Economy

To evaluate the effect of temperature on running economy (RE) and stride parameters in 10 trained male runners (VO2peak 60.8 +/- 6.8 ml . kg (-1) . min (-1)), we used water immersion as a passive temperature manipulation to contrast localised pre-heating, pre-cooling, and thermoneutral interventions prior to running. Runners completed three 10-min treadmill runs at 70 % VO2peak following 40 min of randomised leg immersion in water at 21.0 degrees C (cold), 34.6 degrees C (thermoneutral), or 41.8 degrees C (hot). Treadmill runs were separated by 7 days. External respiratory gas exchange was measured for 30 s before and throughout the exercise and stride parameters were determined from video analysis in the sagittal plane. RE was not affected by prior heating or cooling with no difference in oxygen cost or energy expenditure between the temperature interventions (average VO2 3rd-10th min of exercise: C, 41.6 +/- 3.4 ml . kg (-1) . min (-1); TN, 41.6 +/- 3.0; H, 41.8 +/- 3.5; p = 0.94). Exercise heart rate was affected by temperature (H > TN > C; p < 0.001). During minutes 3 - 5 of running the respiratory-exchange and minute ventilation/oxygen consumption ratios were greater in cold compared with thermoneutral (p < 0.05). Averaged over the full 10 min of exercise, stride length was shorter and stride frequency higher for the C trial compared to TN and H (p < 0.01). Leg temperature manipulation did not influence running economy despite changes in stride parameters that might indicate restricted muscle-tendon elasticity after pre-cooling. Larger changes in stride mechanics than those produced by the current temperature intervention are required to influence running economy.

New Useful Options in Anesthesiological Monitoring

New aspects of rational monitoring in contemporary anesthesiology are discussed. Not only conventional pulsoximetric parameters of circulation and respiration disorders but also new noninvasive methods are suggested to determine blood losses (degree of its compensation), certain parameters of external respiration, gas exchange, and cardiac stroke volume (Fick's principle). Cardiac stroke volume is a cardinal parameter of oxygen transport and consumption. The level of monitoring implemented in the suggested system provides maximum patient safety during surgery. It also provides anesthesiologist with information about mechanisms of circulation and respiration dysfunction.

Extension of the Functional Range of Respiratory and Gas Exchange Responses in Repetitive Hypoxia

External respiration and gas exchange were studied in healthy volunteers during a session of intermittent normobaric hypoxia (INH) consisting of three cycles of breathing alternately a hypoxic mixture (10.7% O2) for 5 min and normal air for 5 min. The ventilatory response increased in the successive cycles of hypoxia and gradually decreased during the normoxic intervals. These changes were accompanied by an increase in carbon dioxide in lung air, which was not eliminated by the increased pulmonary ventilation during the hypoxic intervals. However, the mean oxygen consumption did not change during the INH session because the ventilatory reactivity and breathing depth, as well as the efficiency of oxygen utilization, increased from cycle to cycle.

Regulation of External Respiration and Gas Exchange during a 20-Day Exposure to Sessions of Intermittent Normobaric Hypoxia

A study was made of the effects of a 20-day course of intermittent normobaric hypoxia (INH) on the parameters of gas exchange and the regulation of respiration in healthy volunteers. A phasic change in oxygen consumption at rest was observed: it decreased on the 10th day of the INH course and increased on the 20th day, with a parallel increase in the efficiency of pulmonary ventilation. According to the hypercapnic test, the ventilatory response threshold decreased, whereas ventilatory sensitivity increased; these effects were most pronounced during the first ten days of INH training and still detectable in recovery. It was assumed that the first phase of training (up to the tenth day) is associated with compensatory activation of pulmonary ventilation owing to an increase in peripheral and central chemosensitivity to the CO2 stimulus. In the second phase, which was associated with further slight changes in the parameters of external respiration, the gas exchange level is restored owing to an adaptive increase in efficiency of oxygen utilization in cells and tissues.

MODELLING THE O2 AND CO2 PERMEANCE OF CONFERENCE PEAR

Gas exchange is governed by the combined action of oxygen consumption and carbon dioxide production, and the transport of these gasses by diffusion. The diffusion component is formally neglected and implicitly incorporated in respiration and fermentation parameters of the current Michealis-Menten-based respiration models. The aim was to extend existing modelling approaches by including a diffusion controlled component to quantify the permeance of O2 and CO2. Permeances were estimated using a new gas exchange model which assumes that diffusion can be described by Fick’s first Law. Fick’s first Law can be applied when only one barrier is present. This was shown to be the case for O2 by O2-electrode measurements. The model estimated the permeance per batch on the basis of external gas exchange measurements, internal and external gas conditions, weight and surface per pear. Traditionally, permeances are not estimated, but calculated directly by the Neon method, using Graham’s Law. Permeances estimated using the new model were lower for O2 and CO2 than those found with the Neon method. The lower permeances may be explained by the assumption that the Neon method only assesses the permeance of the skin, while the O2 and CO2 permeances established by using the new model represent all barriers between mitochondria and the external atmosphere. The smaller CO2 permeance found using the new model might be explained by the relatively high pH of the cytosol. INTRODUCTION Gas exchange of fruits is governed by the combined action of oxygen consumption (respiration) and carbon dioxide production (respiration and fermentation) on one hand, and the transport of these gases from and to the inside of the cell by diffusion on the other hand. Only scarce information is available on internal gas concentrations in fruits in literature. Considering only external gas conditions in modelling respiration and fermentation of fruits and vegetables implies that the diffusion part of the process is formally neglected and that the diffusion-oriented effects are implicitly incorporated in model parameters. Several barriers exist in fruits for the transport of gases from outside the product into the cells and the opposite direction (e.g. the skin, flesh, cell wall, membranes and cytoplasm), each exerting its own effect on the overall gas exchange rate. The aim of this article is twofold. Firstly, existing modelling approaches on fruit respiration are extended by including a diffusion controlled component resulting in description of the permeance of the pear for O2 and CO2. Secondly, these model-based estimation of the permeances for O2 and CO2 are compared to the traditionally used Neon method (Schotsmans et al., 2002). Proc. Postharvest Unltd Eds. B.E. Verlinden et al. Acta Hort. 599, ISHS 2003 462 MATERIAL AND METHODS The Gas Exchange/Diffusion Model Nowadays’ general models describing gas exchange of fruits and vegetables are based on external gas conditions, and use a Michaelis-Menten approach. Modelling gas exchange with internal gas conditions may be accomplished by using the existing gas exchange model and exchanging the external for the internal gas conditions. However, the effect of diffusion resistance towards gases of the skin of the fruit should be considered in the gas exchange model when significant differences between internal and external gas conditions are encountered. Under the assumption that there is only one barrier for transport of gasses, namely the skin of the pear, diffusion can be described with Fick’s first law (Burg and Burg, 1965). This Law can be rewritten to the gas exchange rate (Vd in mol kgs) due to the diffusion process by converting the mass flux to the diffusion rate per kg pear (Mp) (Eq. 1)

Changes in the central regulation of respiratory function after a single session of intermittent normobaric hypoxia

Correlations between EEG findings and external respiration and gas exchange indices recorded prior to and after a single session of intermittent normobaric hypoxia were calculated by means of the Neirokartograf (MBN) program. Changes in the central regulation of respiration were observed for a period of more than one hour. The hypoxia caused a decline in EEG coherence in the left hemisphere and a decrease in the statistically significant correlations between the bioelectric rhythms of the β, α, and θ ranges and the external respiration and gas exchange indices.

Metabolic rate and respiratory gas-exchange patterns in tenebrionid beetles from the Negev Highlands, Israel

This study correlates the pattern of external gas exchange with the diel activity of nine species of tenebrionid beetle from the Negev Desert, Israel. The study species are active throughout the summer months when daytime temperatures are high and no rain falls. There were no differences in standard metabolic rate, determined by flow-through respirometry, among the nine species. All the nocturnally active beetles exhibited a form of continuous respiration, whereas the two diurnally active and one crepuscular species exhibited a cyclic form of respiration referred to as the discontinuous gas-exchange cycle (DGC). The DGCs recorded have a long flutter period consisting of miniature ventilations, and 29-48 % of the total CO(2) output occurred during this period. In this study, the flutter period played an important role in the modulation of metabolic rate, in contrast to other studies in which the burst period has been shown to be important. We suggest that the long flutter period is important in reducing respiratory water loss in arid-dwelling arthropods. This study lends support to the hypothesis that discontinuous gas exchange is important in reducing respiratory water loss from beetles that need to minimise dessication because of the high water vapour pressure gradient they experience. If the use of underground burrows were responsible for the evolution of discontinuous gas exchange, then we would expect all nine tenebrionid species to use DGCs since both the nocturnally and diurnally active species bury in the sand during periods of inactivity. We conclude that the activity patterns of the beetles are more important than their habitat associations in designating the type of respiration used.