scholarly journals A test of the oxidative damage hypothesis for discontinuous gas exchange in the locust Locusta migratoria

2012 ◽  
Vol 8 (4) ◽  
pp. 682-684 ◽  
Author(s):  
Philip G. D. Matthews ◽  
Edward P. Snelling ◽  
Roger S. Seymour ◽  
Craig R. White
Keyword(s):  
Gas Exchange ◽  
Oxidative Damage ◽  
Breathing Pattern ◽  
Critical Level ◽  
Locusta Migratoria ◽  
Respiratory Control ◽  
Breath Holding ◽  
Adaptive Value ◽  
Partial Pressures ◽  
Discontinuous Gas Exchange Cycle

The discontinuous gas exchange cycle (DGC) is a breathing pattern displayed by many insects, characterized by periodic breath-holding and intermittently low tracheal O 2 levels. It has been hypothesized that the adaptive value of DGCs is to reduce oxidative damage, with low tracheal O 2 partial pressures ( P O 2 ∼2–5 kPa) occurring to reduce the production of oxygen free radicals. If this is so, insects displaying DGCs should continue to actively defend a low tracheal P O 2 even when breathing higher than atmospheric levels of oxygen (hyperoxia). This behaviour has been observed in moth pupae exposed to ambient P O 2 up to 50 kPa. To test this observation in adult insects, we implanted fibre-optic oxygen optodes within the tracheal systems of adult migratory locusts Locusta migratoria exposed to normoxia, hypoxia and hyperoxia. In normoxic and hypoxic atmospheres, the minimum tracheal P O 2 that occurred during DGCs varied between 3.4 and 1.2 kPa. In hyperoxia up to 40.5 kPa, the minimum tracheal P O 2 achieved during a DGC exceeded 30 kPa, increasing with ambient levels. These results are consistent with a respiratory control mechanism that functions to satisfy O 2 requirements by maintaining P O 2 above a critical level, not defend against high levels of O 2 .

Inspiratory Speech as a Management Option for Spastic Dysphonia

1992 ◽  
Vol 101 (5) ◽  
pp. 375-382 ◽  
Author(s):  
Gordon A. Harrison ◽  
Richard H. Troughear ◽  
Pamela J. Davis ◽  
Alison L. Winkworth
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Voice Quality ◽  
Management Option ◽  
Communication Problems ◽  
Partial Pressures ◽  
The Subject ◽  
And Control ◽  
Laryngeal Resistance

A case study is reported of a subject who has used inspiratory speech (IS) for 6 years as a means of overcoming the communication problems of long-standing adductor spastic dysphonia (ASD). The subject was studied to confirm his use of IS, determine the mechanisms of its production, investigate its effects on ventilatory gas exchange, and confirm that it was perceptually preferable to ASD expiratory speech (ES). Results showed that the production and control of a high laryngeal resistance to airflow were necessary for usable IS. Voice quality was quantitatively and perceptually poor; however, the improved fluency and absence of phonatory spasm made IS the preferred speaking mode for both the listener and the speaker. Transcutaneous measurements of the partial pressures of oxygen and carbon dioxide in the subject's blood were made during extended speaking periods. These measurements indicated that ventilation was unchanged during IS, and that ventilation during ES was similar to the “hyperventilation” state of normal speakers. The reasons for the absence of phonatory spasm during IS are discussed, and the possibility of its use as a noninvasive management option for other ASD sufferers is addressed.

scholarly journals Physiological Effects of Exercising at Different Intensities Wearing TNT or Double-layer Cotton Facemasks Compared to Not Wearing a Mask

2020 ◽  
Author(s):  
Fabrício Braga ◽  
Gabriel Espinosa ◽  
Amanda Monteiro ◽  
Beatriz Marinho ◽  
Eduardo Drummond
Keyword(s):  
Gas Exchange ◽  
Double Layer ◽  
Breathing Pattern ◽  
Pulmonary Ventilation ◽  
Effect Sizes ◽  
Moderate Intensity ◽  
List Type ◽  
Physiological Effects ◽  
Physiological Dead Space ◽  
End Tidal

Abstract We compared the physiological differences between exercising wearing a TNT or a double-layer-cotton (DLC) facemask (FM) and not wearing a mask (NM). Sixteen volunteers underwent 4 sets (S) of 2 sequential bouts (B). B1 and B2 corresponded to light and moderate intensity cycling, respectively. FMs were used as follows: S1: NM; S2: TNT or DLC; S3: DLC or TNT; and S4: NM. Metabolic, pulmonary, and perceptual variables were collected. The main results are expressed as effect sizes and confidence intervals (ES [95%CI]) for TNT and DLC unless otherwise indicated. Compared to NM, FM increased the duty cycle (B1=1.11[0.58-1.61] and 1.53[0.81-2.18]; B2=1.27[0.63-1.84] and 1.93[0.97-2.68]) and decreased breath frequency (B1=0.59[0.23-0.94] and 1.43[0.79-2.07], B2=0.39[0.05-0.71] and 1.33[0.71-1.94]). Only B1 tidal volume increased (0.33[0.09-0.56] and 0.62[0.18-1.05]) enough to avoid a ventilation reduction with TNT but not with DLC (B1=0.52[0.23-0.79]; B2=0.84[0.44-1.22]). Both FMs reduced oxygen saturation in B1 (0.56 [0.07-1.03] and 0.69 [0.09-1.28]) but only DLC did so in B2 (0.66 [0.11-1.13]). Both end tidal CO2 (B1=0.23[0.05-0.4] and 0.71[0.38-1.02]; B2=0.56[0.2-0.9] and 1.20[0.65-1.68]) and mixed-expired-CO2 (B1=0.74[0.38-1.08] 1.71[1.03-2.37], B2=0.94[0.45-1.38] and 1.78[0.97-2.42]) increased with FMs. Ventilatory adaptations imposed during FM exercising influenced blood-lung gas exchange. Larger ESs were seen with DLC. No adverse changes to human health were observed. Novelty Bullets Facemasks affect the breathing pattern by changing the frequency and amplitude of pulmonary ventilation. The augmented ventilatory work increases VO2, VCO2, and RPE and promotes non-concerning drops in SpO2 and CO2 retention. Increased inspiratory and expiratory pressure can account for the reduction in pulmonary physiological dead space.

Incidence of Apnea in Siblings of Sudden Infant Death Syndrome Victims Studied at Home

PEDIATRICS ◽  
1982 ◽  
Vol 70 (1) ◽  
pp. 128-131
Author(s):  
Dorothy H. Kelly ◽  
Joseph Twanmoh ◽  
Daniel C. Shannon
Keyword(s):  
Sudden Infant Death Syndrome ◽  
Infant Death ◽  
Chronic Hypoxia ◽  
Breathing Pattern ◽  
Respiratory Control ◽  
Periodic Breathing ◽  
Sudden Infant Death ◽  
Near Miss ◽  
Sudden Infant ◽  
Sibling Group

Victims of sudden infant death syndrome (SIDS) have been shown to have pathologic abnormalities consistent with chronic hypoxia.1-7 Two groups of infants at high risk of dying of SIDS, near miss infants and subsequent siblings of SIDS victims, have been studied in attempts to demonstrate physiologic abnormalities that could account for these pathologic findings. Investigators have found abnormalities in breathing pattern and the respiratory control system in the former consisting of prolonged sleep apnea, excessive short apnea, periodic breathing, hypoventilation, and depressed response to hypercarbia.8-13 However, studies in the SIDS sibling group have demonstrated varying results of excessive periodic breathing in the home14 and decreased apnea in the laboratory.15

Evaluation of estimates of alveolar gas exchange by using a tidally ventilated nonhomogenous lung model

1997 ◽  
Vol 82 (6) ◽  
pp. 1963-1971 ◽  
Author(s):  
Thierry Busso ◽  
Peter A. Robbins
Keyword(s):  
Gas Exchange ◽  
Lung Model ◽  
Gas Composition ◽  
Breathing Patterns ◽  
Alveolar Volume ◽  
Gas Concentration ◽  
Pulmonary Capillaries ◽  
Partial Pressures ◽  
End Tidal ◽  
Alveolar Gas Exchange

Busso, Thierry, and Peter A. Robbins. Evaluation of estimates of alveolar gas exchange by using a tidally ventilated nonhomogenous lung model. J. Appl. Physiol. 82(6): 1963–1971, 1997.—The purpose of this study was to evaluate algorithms for estimating O2 and CO2 transfer at the pulmonary capillaries by use of a nine-compartment tidally ventilated lung model that incorporated inhomogeneities in ventilation-to-volume and ventilation-to-perfusion ratios. Breath-to-breath O2 and CO2 exchange at the capillary level and at the mouth were simulated by using realistic cyclical breathing patterns to drive the model, derived from 40-min recordings in six resting subjects. The SD of the breath-by-breath gas exchange at the mouth around the value at the pulmonary capillaries was 59.7 ± 25.5% for O2 and 22.3 ± 10.4% for CO2. Algorithms including corrections for changes in alveolar volume and for changes in alveolar gas composition improved the estimates of pulmonary exchange, reducing the SD to 20.8 ± 10.4% for O2 and 15.2 ± 5.8% for CO2. The remaining imprecision of the estimates arose almost entirely from using end-tidal measurements to estimate the breath-to-breath changes in end-expiratory alveolar gas concentration. The results led us to suggest an alternative method that does not use changes in end-tidal partial pressures as explicit estimates of the changes in alveolar gas concentration. The proposed method yielded significant improvements in estimation for the model data of this study.

What hinders pulmonary gas exchange and changes distribution of ventilation in immobilized white rhinoceroses (Ceratotherium simum) in lateral recumbency?

2020 ◽  
Vol 129 (5) ◽  
pp. 1140-1149
Author(s):  
Martina Mosing ◽  
Andreas D. Waldmann ◽  
Muriel Sacks ◽  
Peter Buss ◽  
Jordyn M. Boesch ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Electrical Impedance Tomography ◽  
Electrical Impedance ◽  
Breath Holding ◽  
Dependent Lung ◽  
Regional Ventilation ◽  
Impedance Tomography ◽  
Ventilation And Perfusion ◽  
Lateral Recumbency ◽  
Nondependent Lung

Electrical impedance tomography measurements of regional ventilation and perfusion applied to etorphine-immobilized white rhinoceroses in lateral recumbency revealed a pronounced disproportional shift of the measured ventilation and perfusion toward the nondependent lung. The dependent lung was minimally ventilated and perfused, but still aerated. Perfusion was found primarily around the hilum of the nondependent lung. These shifts can explain the gas exchange impairments found in this study. Breath holding can redistribute ventilation.

Gas Exchange

2017 ◽  
Author(s):  
John W. Kreit
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Capillary Blood ◽  
Pressure Gradients ◽  
Arterial Blood ◽  
Pulmonary Capillary ◽  
Partial Pressures ◽  
Pulmonary Capillary Blood ◽  
And Diffusion

Gas Exchange explains how four processes—delivery of oxygen, excretion of carbon dioxide, matching of ventilation and perfusion, and diffusion—allow the respiratory system to maintain normal partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) in the arterial blood. Partial pressure is important because O2 and CO2 molecules diffuse between alveolar gas and pulmonary capillary blood and between systemic capillary blood and the tissues along their partial pressure gradients, and diffusion continues until the partial pressures are equal. Ventilation is an essential part of gas exchange because it delivers O2, eliminates CO2, and determines ventilation–perfusion ratios. This chapter also explains how and why abnormalities in each of these processes may reduce PaO2, increase PaCO2, or both.

Understanding pulmonary gas exchange: ventilation-perfusion relationships

2004 ◽  
Vol 287 (6) ◽  
pp. L1071-L1072 ◽  
Author(s):  
John B. West
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Theoretical Study ◽  
Pulmonary Gas Exchange ◽  
Alveolar Air ◽  
Factors Affecting ◽  
Historical Significance ◽  
Partial Pressures ◽  
Classic Papers

This essay looks at the historical significance of four APS classic papers that are freely available online: Fenn WO, Rahn H, and OTIS AB. A theoretical study of the composition of the alveolar air at altitude. Am J Physiol 146: 637-653. 1946 ( http://ajplegacy.physiology.org/cgi/reprint/146/5/637 ). Rahn H. A concept of mean alveolar air and the ventilation-bloodflow relationships during pulmonary gas exchange. Am J Physiol 158: 21-30, 1949 ( http://ajplegacy.physiology.org/cgi/reprint/158/1/21) ). Riley RL. And Cournand A. "Ideal" Alveolar air and the analysis of ventilation-perfusion relationships in the lungs. J Appl Physiol 1: 825-847. 1949 ( http://jap.physiology.org/cgi/reprint/1/12/825) . Riley RL. And Cournand A. Analysis of factors affecting partial pressures of oxygen and carbon dioxide in gas and blood of lungs: theory. J Appl Physiol 4: 77-101. 1951 ( http://jap.physiology.org/cgi/reprint/4/2/77) .

scholarly journals Breathing pattern and gas exchange at peak exercise in COPD patients with and without tidal flow limitation at rest

2001 ◽  
Vol 17 (6) ◽  
pp. 1120-1127 ◽  
Author(s):  
O. Díaz ◽  
C. Villafranca ◽  
H. Ghezzo ◽  
G. Borzone ◽  
A. Leiva ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Breathing Pattern ◽  
Tidal Flow ◽  
Peak Exercise ◽  
Flow Limitation ◽  
Copd Patients

A Correlation between Radiotherapy Dose on the Mediastinal Lymphoma and Cardiovascular Dose with Using Respiratory Control System

2017 ◽  
Vol 62 (5) ◽  
pp. 40-46
Author(s):  
Е. Филатова ◽  
E. Filatova ◽  
О Ламанова ◽  
O Lamanova ◽  
П. Филатов ◽  
...  
Keyword(s):  
Correlation Coefficient ◽  
Respiratory Control ◽  
Threshold Level ◽  
Ascending Aorta ◽  
Reproductive Age ◽  
Breath Holding ◽  
Average Dose ◽  
Mediastinal Lymphoma ◽  
Coefficient Corrélation ◽  
Radiotherapy Dose

Purpose: To find a correlation between prescribed dose on the irradiation area and dose on heart and ascending aorta, using the "breath holding" method in classical radiotherapy course for patients with Hodgkin and non-Hodgkin mediastinal lymphomas. Material and methods: For patients of reproductive age with diagnose Hodgkin, non-Hodgkin mediastinal lymphomas we conducted radiotherapy with contouring of tumor, and critical structures, include heart and ascending aorta. Radiotherapy was conducted on breath holding (ABC) for shielding radiation dose from heart, ascending aorta and lungs. We did calculations of length and diameter of the contoured aorta and dose that it and heart took. Also, we did correlation calculation of relationship between prescribed dose on the tumor and doses cover to the heart and aorta on 6 and 10 MV nominal energies. Results: According to the protocol RTOG 1005 for the heart zone, exceeding the threshold level for V20 < 5 % occurred in 11 cases out 21, and 8 cases from them are for 10 MV energy. For V10 < 30 % it happened in nine cases from 21, and seven cases from them are for 10 MV energy too. The correlation coefficient between the prescribed dose and the received dose for protocol RTOG 1005 V10 < 30 % was 0.71 and it showed the highest value. This index is lower on 13 % for protocol RTOG 0623 (V67) – 0..58, and it has the weakest coefficient correlation (V33) – 0.45. The value of the correlation coefficient for the aorta decreased with an increase in the volume to which the prescribed dose of the irradiation area falls and, consequently a 10 and 20 % of the aorta volume is getting a maximum value from the prescribed dose. Conclusion: Our research showed what contouring of ascending aorta is obligatorily procedure, because the average dose on it was 10.73 Gy for 10 MV and 6.50 Gy for 6 MV energies. It is obvious that using 6 MV energy is more organ-preserving method of thea radiotherapy treatment when using a such techniques as ABC. It is a very important to study the issue of the permissible dose per volume of ascending aorta without critical consequences for cardiovascular system. In addition, it particularly important if we take into account that all patients had a chemotherapy course before radiation therapy which also caused cardiotoxicity.

Anthropometric and other factors affecting respiratory responses to carbon dioxide in New Guineans

1974 ◽  
Vol 268 (893) ◽  
pp. 363-373 ◽  
Keyword(s):  
Linear Regression ◽  
Tidal Volume ◽  
Vital Capacity ◽  
Breathing Pattern ◽  
Respiratory Control ◽  
Control Mechanisms ◽  
Men And Women ◽  
Factors Affecting ◽  
Residual Difference ◽  
The Difference

A CO 2 rebreathing test was used to determine the breathing pattern and the ventilatory response to CO 2 in 15 Caucasians and 140 New Guineans (coastal and highland men and women, and male highlanders on the coast). The breathing pattern was analysed in terms of the slope and intercept ( M and K ) of the linear regression of ventilation on tidal volume: V e = M ( V t — K ), and of the interpolated tidal volume at a ventilation of 30 1 min-1 (V t,30 ). Each of these parameters bears a common relation to vital capacity throughout the groups studied. The CO 2 response was analysed in terms of the slope and intercept ( S and B ) of the linear regression of ventilation on P CO 2 : V e = S ( P CO 2 — B ). B is lower in women than in men. S is a function of vital capacity, and this relation accounts for the difference in CO 2 sensitivity between men and women, and for part of the difference between the resident highland and coastal groups; part is attributable to altitude-adaptation and disappears on migration. In all these respects, New Guineans resemble Caucasians, and the results demonstrate the importance of the size of the vital capacity in influencing the setting of the respiratory control mechanisms. In addition, there is a residual difference between the ethnic groups, with the New Guineans having the lower CO 2 sensitivities and thus a greater tolerance of CO 2 loads.

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