Handbook of Physiology: A Critical, Comprehensive Presentation of Physiological Knowledge and Concepts. Section 3: The Respiratory System. Vol 4: Gas Exchange

1987 ◽  
Vol 62 (11) ◽  
pp. 1068
Author(s):  
Rolf D. Hubmayr
Keyword(s):  
Gas Exchange ◽  
Respiratory System

Words used by the breathless patient in COPD and enhancing therapeutic care

2021 ◽  
Vol 13 (3) ◽  
pp. 1-7
Author(s):  
Susan Harrison
Keyword(s):  
Gas Exchange ◽  
Respiratory System ◽  
Service Users ◽  
Physiological Changes ◽  
Shortness Of Breath ◽  
Holistic View ◽  
Comprehensive List ◽  
Distressing Symptom ◽  
Assessment And Treatment ◽  
Therapeutic Care

Shortness of breath, dyspnoea and breathlessness are collective terms to describe the awareness of inadequate gas exchange within the respiratory system. Varying mechanisms, behavioural and physiological changes are caused by this ventilation–perfusion mismatch. This complex sensation encompasses many diverse concepts. The spectrum of language and words used as a consequence of this sensation vary from quality and intensity to emotions and feelings. Matching the phrases to the cause supports understanding. Studies reviewed produced clusters of verbal descriptors which reflect the multidimensional input as a consequence of being out of breath. Using these clusters has produced a comprehensive list of twelve words known as ‘The Dyspnoea 12’ which, when used, quantifies the severity of this debilitating and extremely distressing symptom. Could these verbal descriptors be used to aid the assessment and treatment of their cause in service users and provide a more holistic view to a widespread problem?

Excretion-retention diagram to evaluate gas exchange properties of vertebrate respiratory systems

1982 ◽  
Vol 243 (3) ◽  
pp. R329-R338
Author(s):  
A. Zwart ◽  
S. C. Luijendijk
Keyword(s):  
Gas Exchange ◽  
Respiratory System ◽  
Visual Inspection ◽  
Mathematical Formulation ◽  
Mass Conservation ◽  
Correct Choice ◽  
Model Free ◽  
Respiratory Systems ◽  
Complex Relationships ◽  
Ventilation And Perfusion

Excretion [E = (PE - PI)/(PV - PI)] and retention [R = (Pa - PI)/(PV -PI)]are completely model-free defined variables which describe the dual input-output black-box representation of vertebrate respiratory systems under steady-state conditions. In the excretion-retention diagram (E-R diagram), E is plotted as a function of R. The application of the principle of mass conservation confines the possible combinations of E and R for a gas with a blood-gas partition coefficient, lambda, in a respiratory system with an overall ventilation, VT, and an overall perfusion, QT, to E = (lambda QT/VT) (1 - R). In general, E can be described as a continuous function of R. The mathematical formulation of this function depends on the configuration of the respiratory system. Easily recognizable curvatures are obtained for counter-cross, and cocurrent systems with and without parallel inhomogeneities. Visual inspection of actual E and R data displayed in an E-R diagram therefore allows the correct choice of the configuration of the respiratory system to be eventually used for further parameter estimation schemes. The E-R diagram is also a powerful tutorial tool for visualizing the complex relationships between the gas exchange of agents with different physical properties and the consequences of changes in ventilation and perfusion distribution within the respiratory system on gas transport.

Larval respiratory systems of two anthomyiid flies, Delia radicum and Delia antiqua (Diptera: Anthomyiidae)

2005 ◽  
Vol 137 (2) ◽  
pp. 163-168 ◽  
Author(s):  
D.G. Biron ◽  
D. Coderre ◽  
S. Fournet ◽  
J.P. Nénon ◽  
J. Le Lannic ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Respiratory System ◽  
Host Plants ◽  
Delia Radicum ◽  
Delia Antiqua ◽  
Larval Instars ◽  
First Instar ◽  
Respiratory Systems

AbstractThe first-instar larvae of Delia radicum (L.) and Delia antiqua (Meigen) enter host plants to feed in galleries. These galleries can be filled by a liquid resulting from the putrefaction of the host. In this study, we show that D. radicum and D. antiqua larvae have a metapneustic respiratory system in the first instar and an amphipneustic respiratory system in the second instar, as observed in the majority of cyclorrhaphous Diptera. In addition, we observed four spatulate, ramified structures on the postabdominal spiracles in all three larval instars. We propose that these structures facilitate gas exchange (CO2 and O2), especially in the first-instar larvae when they feed in liquid-filled galleries.

scholarly journals Radiological pattern in ARDS patients: partitioned respiratory mechanics, gas exchange and lung recruitability

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Silvia Coppola ◽  
Tommaso Pozzi ◽  
Martina Gurgitano ◽  
Alessandro Liguori ◽  
Ejona Duka ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Respiratory System ◽  
Respiratory Mechanics ◽  
Recruitment Maneuver ◽  
Blood Gas Analysis ◽  
Gas Analysis ◽  
Driving Pressure ◽  
Lung Weight ◽  
Focal Pattern ◽  
Lung Ct

Abstract Background The ARDS is characterized by different degrees of impairment in oxygenation and distribution of the lung disease. Two radiological patterns have been described: a focal and a diffuse one. These two patterns could present significant differences both in gas exchange and in the response to a recruitment maneuver. At the present time, it is not known if the focal and the diffuse pattern could be characterized by a difference in the lung and chest wall mechanical characteristics. Our aims were to investigate, at two levels of PEEP, if focal vs. diffuse ARDS patterns could be characterized by different lung CT characteristics, partitioned respiratory mechanics and lung recruitability. Methods CT patterns were analyzed by two radiologists and were classified as focal or diffuse. The changes from 5 to 15 cmH2O in blood gas analysis and partitioned respiratory mechanics were analyzed. Lung CT scan was performed at 5 and 45 cmH2O of PEEP to evaluate lung recruitability. Results One-hundred and ten patients showed a diffuse pattern, while 58 showed a focal pattern. At 5 cmH2O of PEEP, the driving pressure and the elastance, both the respiratory system and of the lung, were significantly higher in the diffuse pattern compared to the focal (14 [11–16] vs 11 [9–15 cmH2O; 28 [23–34] vs 21 [17–27] cmH2O/L; 22 [17–28] vs 14 [12–19] cmH2O/L). By increasing PEEP, the driving pressure and the respiratory system elastance significantly decreased in diffuse pattern, while they increased or did not change in the focal pattern (Δ15-5: − 1 [− 2 to 1] vs 0 [− 1 to 2]; − 1 [− 4 to 2] vs 1 [− 2 to 5]). At 5 cmH2O of PEEP, the diffuse pattern had a lower lung gas (743 [537–984] vs 1222 [918–1974] mL) and higher lung weight (1618 [1388–2001] vs 1222 [1059–1394] g) compared to focal pattern. The lung recruitability was significantly higher in diffuse compared to focal pattern 21% [13–29] vs 11% [6–16]. Considering the median of lung recruitability of the whole population (16.1%), the recruiters were 65% and 22% in the diffuse and focal pattern, respectively. Conclusions An early identification of lung morphology can be useful to choose the ventilatory setting. A diffuse pattern has a better response to the increase of PEEP and to the recruitment maneuver.

Time transient gas exchange in the respiratory system

1993 ◽  
Vol 12 (3) ◽  
pp. 64-70 ◽  
Author(s):  
S.P. Tomlinson ◽  
J. Lo ◽  
D.G. Tilley
Keyword(s):  
Gas Exchange ◽  
Respiratory System

scholarly journals Positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome: the heterogeneous effects

Critical Care ◽  
2021 ◽  
Vol 25 (1) ◽  
Author(s):  
Davide Chiumello ◽  
Matteo Bonifazi ◽  
Tommaso Pozzi ◽  
Paolo Formenti ◽  
Giuseppe Francesco Sferrazza Papa ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Respiratory System ◽  
Dead Space ◽  
Respiratory Mechanics ◽  
Peep Level ◽  
Lung Mechanics ◽  
Mechanical Power ◽  
Respiratory System Compliance ◽  
Lung Elastance ◽  
Lung Stress

Abstract Background We hypothesized that as CARDS may present different pathophysiological features than classic ARDS, the application of high levels of end-expiratory pressure is questionable. Our first aim was to investigate the effects of 5–15 cmH2O of PEEP on partitioned respiratory mechanics, gas exchange and dead space; secondly, we investigated whether respiratory system compliance and severity of hypoxemia could affect the response to PEEP on partitioned respiratory mechanics, gas exchange and dead space, dividing the population according to the median value of respiratory system compliance and oxygenation. Thirdly, we explored the effects of an additional PEEP selected according to the Empirical PEEP-FiO2 table of the EPVent-2 study on partitioned respiratory mechanics and gas exchange in a subgroup of patients. Methods Sixty-one paralyzed mechanically ventilated patients with a confirmed diagnosis of SARS-CoV-2 were enrolled (age 60 [54–67] years, PaO2/FiO2 113 [79–158] mmHg and PEEP 10 [10–10] cmH2O). Keeping constant tidal volume, respiratory rate and oxygen fraction, two PEEP levels (5 and 15 cmH2O) were selected. In a subgroup of patients an additional PEEP level was applied according to an Empirical PEEP-FiO2 table (empirical PEEP). At each PEEP level gas exchange, partitioned lung mechanics and hemodynamic were collected. Results At 15 cmH2O of PEEP the lung elastance, lung stress and mechanical power were higher compared to 5 cmH2O. The PaO2/FiO2, arterial carbon dioxide and ventilatory ratio increased at 15 cmH2O of PEEP. The arterial–venous oxygen difference and central venous saturation were higher at 15 cmH2O of PEEP. Both the mechanics and gas exchange variables significantly increased although with high heterogeneity. By increasing the PEEP from 5 to 15 cmH2O, the changes in partitioned respiratory mechanics and mechanical power were not related to hypoxemia or respiratory compliance. The empirical PEEP was 18 ± 1 cmH2O. The empirical PEEP significantly increased the PaO2/FiO2 but also driving pressure, lung elastance, lung stress and mechanical power compared to 15 cmH2O of PEEP. Conclusions In COVID-19 ARDS during the early phase the effects of raising PEEP are highly variable and cannot easily be predicted by respiratory system characteristics, because of the heterogeneity of the disease.

Fluid Flow and Particle Dispersion in Acini During Asynchronous Ventilation

2008 ◽  
Author(s):  
Sudhaker Chhabra ◽  
Ajay K. Prasad
Keyword(s):  
Carbon Dioxide ◽  
Fluid Flow ◽  
Gas Exchange ◽  
Surface Area ◽  
Opposite Direction ◽  
Respiratory System ◽  
Human Lung ◽  
Alveolar Epithelium ◽  
Particle Dispersion ◽  
Conducting Airways

The human lung comprises 24 generations of dichotomously branching tubes known as bronchi [1]. Functionally, these generations can be categorized as: (1) conducting airways which are non-alveolated and comprise the first 16 generations, and (2) the acini which consist of flexible, alveolated airways and are responsible for gas exchange. The alveoli are the most important units of the human respiratory system and provide large surface area (about 70–80 m2) for efficient gas exchange; oxygen diffuses into the blood through the alveolar epithelium, whereas carbon dioxide diffuses in the opposite direction from the blood to the lung.

ICU treatment of respiratory failure

2018 ◽  
Author(s):  
Matt Wise ◽  
Paul Frost
Keyword(s):  
Carbon Dioxide ◽  
Respiratory Failure ◽  
Gas Exchange ◽  
Motor Neuron ◽  
Motor Neuron Disease ◽  
Respiratory System ◽  
Acute Asthma ◽  
Compensatory Mechanisms ◽  
Asthma Attack ◽  
Icu Treatment

Respiratory failure is a syndrome characterized by defective gas exchange due to inadequate function of the respiratory system. There is a failure to oxygenate blood (hypoxaemia) and/or eliminate carbon dioxide (hypercapnoea). Respiratory failure can develop over years when it is due to conditions such as kyphoscoliosis or motor neuron disease, or minutes in the case of an acute asthma attack or pneumothorax. In this context, respiratory failure is often called acute (e.g. asthma), chronic (e.g. kyphoscoliosis), or acute on chronic (kyphoscoliosis complicated by pneumonia). Chronic respiratory failure is characterized by compensatory mechanisms which aim to adjust the pH of the blood back to the normal physiological range and involve the retention of bicarbonate by the kidney. This topic covers the etiology of respiratory failure as well as signs, symptoms, diagnosis, investigations, prognosis, and treatment.

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