Breathing in Rana Pipiens: the Mechanism of Ventilation

1990 ◽  
Vol 154 (1) ◽  
pp. 537-556 ◽  
Author(s):  
TIMOTHY ZOLTAN VITALIS ◽  
GRAHAM SHELTON
Keyword(s):  
Lung Volume ◽  
Rana Pipiens ◽  
Buccal Cavity ◽  
Air Flow ◽  
Lung Ventilation ◽  
Jet Stream ◽  
Pulmonary Pressure ◽  
Simultaneous Measurements ◽  
Low Amplitude ◽  
Ventilation Of The Lungs

The mechanism and pattern of ventilation in unrestrained Rana pipiens were investigated by simultaneous measurements of pulmonary pressure, buccal pressure and air flow at the nostrils. The buccal cavity was ventilated continuously at a rate of 90±3.2oscillations min−1 by low-amplitude pressure swings above and below atmospheric. The lungs were ventilated intermittently by the buccal pump at a rate of 6.3±0.8breathsmin−1. Expiration of gas from the nostrils occurred on two occasions during a lung ventilation. Ventilation of the lungs was achieved by precise timing of two valves, the nostrils and glottis. The timing of the valves determined the volume of expiratory flow on these two occasions and its relationship to inspiratory flow. Thus, the breathing movements could cause inflation, deflation, or no change in the lung volume. Periodically the lung was inflated by a sequence of successive breaths. During inflations the nostrils closed simultaneously with glottal opening and almost no gas was expired during the first expiratory phase. This caused a complete mixing of buccal contents and pulmonary gas and this mixture was pumped back into the lung. Deflations were characterized by a delay in nostril closing that resulted in a large outflow of gas from the lung and buccal cavity during the first phase of expiration. More gas left the system than was pumped into the lungs. The results suggest that coherent air flow from glottis to nostrils, as required by the ‘jet stream’ hypothesis of Gans et al. (1969), is not likely to occur.

Breathing movements in the frog Rana pipiens. I. The mechanical events associated with lung and buccal ventilation

1975 ◽  
Vol 53 (3) ◽  
pp. 332-344 ◽  
Author(s):  
N. H. West ◽  
D. R. Jones
Keyword(s):  
Rana Pipiens ◽  
Buccal Cavity ◽  
Lung Ventilation ◽  
Cavity Pressure ◽  
Normal Pattern ◽  
Large Pressure ◽  
Dilator Muscle ◽  
Recovery Stroke ◽  
Two Phases ◽  
Low Pressures

The normal pattern of breathing movements in Rana pipiens has been studied by recording pressure and volume changes in the buccal cavity and lungs, and electromyograms from the muscles involved in this activity. Two types of breathing movement were obtained, one concerned with ventilation of the buccal cavity (buccal cycles) and the other with lung ventilation (lung cycles). Only in the latter type of movement were the nares and glottis actively involved. During buccal cycles the nares remained open and the glottis closed, so although excursions of the buccal floor were some two-thirds of the magnitude of those occurring during lung cycles, only low pressures were generated. The onset of a lung cycle was signalled by activity in the laryngeal dilator muscle. When the glottis opened, lung pressure and volume decreased, and buccal cavity pressure and volume increased. After closure of the nares, the buccal floor was rapidly elevated by the activity of the breathing muscles and air was forced into the lungs from the buccal cavity. At peak pressure in the lungs and buccal cavity the glottis closed and nares opened. The recovery stroke of the buccal pump was passive. No evidence was found for large pressure differentials between the buccal cavity and lungs when the glottis was open, and air-flow recordings at the external nares showed two phases of flow during each buccal cycle and four phases with each lung ventilation cycle.

Effects of lung volume and O2 and CO2 content on cutaneous gas exchange in frogs

1986 ◽  
Vol 251 (5) ◽  
pp. R941-R946
Author(s):  
G. M. Malvin ◽  
M. P. Hlastala
Keyword(s):  
Gas Exchange ◽  
Mass Spectrometer ◽  
Lung Volume ◽  
Rana Pipiens ◽  
Lung Ventilation ◽  
Small Sample ◽  
Cholinergic Nerves ◽  
Lung Inflation ◽  
Sample Chamber ◽  
Cutaneous Respiration

The effects of lung O2 and CO2 content and volume on cutaneous gas exchange and perfusion were investigated in the frog, Rana pipiens. (Ha)-anesthetized frogs were equilibrated with 9.5% Freon-22 (Fr, chlorodifluoromethane) and 1.1% Ha. Cutaneous elimination of Fr, Ha, and CO2 into a small sample chamber on the abdomen was measured with a mass spectrometer. Introducing an air mixture into the lung decreased cutaneous Fr, Ha, and CO2 elimination. Lung inflation with an O2 mixture decreased cutaneous gas elimination more than with the air mixture. Inflation with a N2 mixture had no effect. The response to lung inflation with the air mixture was not affected by adding 4.8% CO2 to the air mixture or by atropine. Voluntary lung ventilation decreased CO2 and Fr elimination. The results indicate that intrapulmonary O2 is a factor regulating skin breathing. If a change in lung volume is also a factor, it requires a concomitant change in lung O2. Intrapulmonary CO2 and cholinergic nerves are not involved in cutaneous respiration across the abdomen.

scholarly journals Ventilation and partitioning of oxygen uptake in the frog Rana pipiens: effects of hypoxia and activity

1986 ◽  
Vol 126 (1) ◽  
pp. 453-468 ◽  
Author(s):  
A. W. Pinder ◽  
W. W. Burggren
Keyword(s):  
Oxygen Uptake ◽  
Lung Volume ◽  
Rana Pipiens ◽  
Lung Ventilation ◽  
Ventilation Rate ◽  
Irregular Pattern ◽  
C 23

Pulmonary and cutaneous oxygen uptake (MO2) and lung ventilation were measured in frogs floating in water with access to air in respirometers, with and without ventilation of the skin provided by stirring. The frogs were exposed to hypoxia in both water and air, and were variably active. In inactive frogs floating in unstirred respirometers at 25 degrees C, 23% of total MO2 is through the skin. Activity of the animal increases total MO2. and also ventilates the skin, so that cutaneous MO2 increases with increasing total MO2. When the respirometer is stirred, cutaneous MO2 increases to 35% of total MO2 in resting animals. Activity no longer affects cutaneous MO2. Lung ventilation volume is directly proportional to lung ventilation rate in normoxia. Ventilation rate, and therefore ventilation volume, is proportional to pulmonary MO2. Ventilation rate approximately doubles in hypoxia (PO2 = 52 mmHg). The pattern of ventilation also changes in hypoxia, from a very irregular pattern in normoxia to one showing regular, large oscillations of lung volume over several ventilation movements. Increased lung ventilation, enhancing pulmonary MO2, is the primary adjustment to increased O2 demand. Partitioning of MO2 shifts towards the lung during both activity and hypoxia. In both cases, however, ventilation of the skin can supplement total MO2 by increasing absolute levels of cutaneous MO2.

Breathing movements in the frog Rana pipiens. II. The power output and efficiency of breathing

1975 ◽  
Vol 53 (3) ◽  
pp. 345-353 ◽  
Author(s):  
N. H. West ◽  
D. R. Jones
Keyword(s):  
Body Weight ◽  
Power Output ◽  
Rana Pipiens ◽  
Buccal Cavity ◽  
Respiratory Muscles ◽  
Lung Ventilation ◽  
Pressure Change ◽  
Mechanical Efficiency ◽  
Lung Inflation ◽  
Anticlockwise Direction

The work done by the buccal cavity during buccal and lung ventilation cycles has been estimated from measurement of the area enclosed by pressure–volume loops for each cycle. The loops cycled in an anticlockwise direction with respect to time during buccal cycles. On the other hand, pressure–volume loops from the lungs cycled clockwise, showing that work was being done on the lungs by the buccal pump. Inflation and deflation of the buccal cavity from a syringe, in curarized frogs, gave a clockwise loop enclosing about 5.5–6.5% of the area enclosed by a naturally generated loop of the same pressure and volume. However, inflation and deflation of the lungs gave a loop which enclosed an area virtually identical with that obtained from a normally generated sequence of lung inflation and deflation. The power output of the buccal pump was directly proportional to body weight, the major determinant of the former being the larger buccal volume rather than pressure change as body weight increased. The mechanical efficiency of the buccal pump varied from 0.4% to 16.2%, efficiency increasing with increased power output over most of the physiological range. Mean efficiency of all buccal movements was calculated to be 8% and, at this value of efficiency, oxygen consumption of the respiratory muscles was 0.89 ml O2 100 g−1 min−1. In Rana pipiens at rest the oxygen cost of breathing appears to be about 5% of the total resting metabolism.

MECHANICAL VENTILATION OF THE LUNGS WITH A TARGETED TIDAL VOLUME IN NEWBORNS AND INFANTS WITH VARIOUS LUNG DISEASES

2021 ◽  
Vol 100 (5) ◽  
pp. 76-82
Author(s):  
A.V. Mostovoy ◽  
◽  
S.S. Mezhinsky ◽  
A.L. Karpova ◽  
A.N. Nikolishin ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Lung Diseases ◽  
Lung Ventilation ◽  
First Year ◽  
Lung Pathology ◽  
Pathological Conditions ◽  
Artificial Lung Ventilation ◽  
First Year Of Life ◽  
Ventilation Of The Lungs ◽  
Selection Of

The review presents and systematizes the current provisions on artificial lung ventilation (ALV) with a guaranteed or target tidal volume as the most effective and safe mode of ALV in neonatal practice. The application of this method of respiratory support is described. The authors present the main provisions on the optimal selection of the target tidal volume in various pathological conditions. The use of various modes of ALV in combination with a guaranteed tidal volume makes it possible to prevent or reduce the harmful impact of ALV in patients with acute and chronic lung pathology, in newborns and children in the first year of life.

scholarly journals Assessment of the influence of lung inflation state on the quantitative parameters derived from hyperpolarized gas lung ventilation MRI in healthy volunteers

2019 ◽  
Vol 126 (1) ◽  
pp. 183-192 ◽  
Author(s):  
Paul J. C. Hughes ◽  
Laurie Smith ◽  
Ho-Fung Chan ◽  
Bilal A. Tahir ◽  
Graham Norquay ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Lung Volume ◽  
Lung Ventilation ◽  
Lung Volumes ◽  
Lung Inflation ◽  
Longitudinal Measurements ◽  
Anatomical Images ◽  
Lower Lung ◽  
Ventilation Heterogeneity ◽  
Residual Capacity

In this study, the effect of lung volume on quantitative measures of lung ventilation was investigated using MRI with hyperpolarized 3He and 129Xe. Six volunteers were imaged with hyperpolarized 3He at five different lung volumes [residual volume (RV), RV + 1 liter (1L), functional residual capacity (FRC), FRC + 1L, and total lung capacity (TLC)], and three were also imaged with hyperpolarized 129Xe. Imaging at each of the lung volumes was repeated twice on the same day with corresponding 1H lung anatomical images. Percent lung ventilated volume (%VV) and variation of signal intensity [heterogeneity score (Hscore)] were evaluated. Increased ventilation heterogeneity, quantified by reduced %VV and increased Hscore, was observed at lower lung volumes with the least ventilation heterogeneity observed at TLC. For 3He MRI data, the coefficient of variation of %VV was <1.5% and <5.5% for Hscore at all lung volumes, while for 129Xe data the values were 4 and 10%, respectively. Generally, %VV generated from 129Xe images was lower than that seen from 3He images. The good repeatability of 3He %VV found here supports prior publications showing that percent lung-ventilated volume is a robust method for assessing global lung ventilation. The greater ventilation heterogeneity observed at lower lung volumes indicates that there may be partial airway closure in healthy lungs and that lung volume should be carefully considered for reliable longitudinal measurements of %VV and Hscore. The results suggest that imaging patients at different lung volumes may help to elucidate obstructive disease pathophysiology and progression. NEW & NOTEWORTHY We present repeatability data of quantitative metrics of lung function derived from hyperpolarized helium-3, xenon-129, and proton anatomical images acquired at five lung volumes in volunteers. Increased regional ventilation heterogeneity at lower lung inflation levels was observed in the lungs of healthy volunteers.

scholarly journals Airway to Lung Volume Ratio on CT is Associated with Pulmonary Function Transition from Obstructive to Restrictive Pattern in Obesity

2022 ◽  
Author(s):  
Xin Yu ◽  
Ming-Hui Zhang ◽  
Yan-Hao Huang ◽  
Yu Deng ◽  
You-Zhen Feng ◽  
...  
Keyword(s):  
Pulmonary Function ◽  
Lung Volume ◽  
Volume Ratio ◽  
Lung Ventilation ◽  
Forced Expiratory Volume ◽  
Obese Adults ◽  
Obese Adolescents ◽  
Wall Area ◽  
Adolescents And Adults ◽  
Airway Tree

Abstract Background: Obesity is associated with excessive airway collapse and reduced lung volume; it is unknown whether it affects airway-lung interactions. We sought to compare the airway tree to lung volume ratio, assessed by CT, in obese individuals with and without ventilation disorders.Methods: Participants underwent inspiratory chest CT and pulmonary function. The percentage ratio of the whole airway tree to lung volume, automatically segmented via deep learning, was defined as CT airway volume percent (AWV%). Total airway count (TAC), airway wall area percent (WA%), and other CT indexes were also measured. Results: We evaluated 88 participants including adolescents(age: 14-18, n= 12) and adults (age: 19-25, n= 17; age: 26-35, n= 39; age> 35, n= 20). Obese adolescents had higher forced vital capacity (FVC) (P = 0.001) and lower AWV% (P = 0.008) than obese adults (age >35). Among obese adults, participants with restrictive disorders had larger AWV% (P < 0.001) and those with obstructive disorders showed smaller AWV% (P < 0.001) compared to participants with normal ventilation. AWV% was positively correlated with age and forced expiratory volume in 1 second (FEV1)/FVC and adversely related to FVC (P< 0.05 for all), and in multivariate models, AWV% independently predicted FEV1/FVC (R2 = 0.49, P < 0.001) and FVC (R2 = 0.60, P < 0.001).Conclusion: Transitions in lung function patterns between obese adolescents and adults are associated with airway to lung ratios. The obesity-induced disproportion between the airway tree and lung volume may adversely affect and complicate lung ventilation.

The initiation of diving apnoea in the frog, Rana pipiens

1976 ◽  
Vol 64 (1) ◽  
pp. 25-38
Author(s):  
N. H. West ◽  
D. R. Jones
Keyword(s):  
Electrical Stimulation ◽  
Water Level ◽  
Rana Pipiens ◽  
Buccal Cavity ◽  
Respiratory Muscles ◽  
Normal Pattern ◽  
Water Head ◽  
Response To Water ◽  
Water Meniscus ◽  
Stimulation Of

1. Diving apnoea in Rana pipiens was initiated by submerging the external nares. As the water level was raised above the frog, both buccal and lung pressure increased by an amount corresponding to the water head. During submergence the external nares remained closed, although the apnoeic period was punctuated by ventilation movements which moved gas between the lungs and buccal cavity. 2. Bilateral section of the ophthalmic nerves did not alter the normal pattern of ventilation in air, although it often resulted in the intake of water into the buccal cavity on submergence. Introduction of water into the buccal cavity, either naturally as in denervates or by injection through a catheter in intact frogs, triggered sustained electromyographical activity in some respiratory muscles. 3. Electroneurograms recorded from the cut peripheral end of an ophthalmic nerve showed that receptors in the external narial region were stimulated by movement of a water meniscus across them. Activity could also be recorded in the ophthalmic nerve in response to water flow past the submerged nares. Punctate stimulation of the narial region confirmed that these receptors were mechanosensitive. 4. Bilateral electrical stimulation of the central ends of cut ophthalmic nerves in lightly anaesthetized frogs caused apnoea with a latency of less than 200 ms. The external nares remained closed throughout the period of stimulation although buccal pressure events, resembling underwater ventilation movements, occurred when stimulation was prolonged.

Relation between flow, curvilinearity, and density dependence of pulmonary pressure-flow curves

1980 ◽  
Vol 48 (5) ◽  
pp. 878-885 ◽  
Author(s):  
C. Lisboa ◽  
L. D. Wood ◽  
J. Jardim ◽  
P. T. Macklem
Keyword(s):  
Reynolds Number ◽  
Density Dependence ◽  
Lung Volume ◽  
Normal Subjects ◽  
Ensemble Averaging ◽  
Flow Curves ◽  
Pressure Flow ◽  
Pulmonary Pressure ◽  
Lung Capacity ◽  
Rate Comparison

In nine normal subjects we measured pulmonary pressure-flow curves by ensemble averaging over 20 breaths and solving the equation P = K'V alpha where P is flow-resistive pressure, K' is slope, 5 V is flow, and alpha is curvilinearity. The study was performed at four lung volumes from 37 to 73% of total lung capacity, with the subjects breathing air or HeO2. K' was lower at every lung volume during HeO2 breathing, whereas the exponent alpha was uninfluenced by either lung volume or HeO2 breathing. Although alpha increased with flow rate, comparison of air and HeO2 curves revealed that alpha was not uniquely related to Reynolds' number. Furthermore there was no correlation between curvilinearity and the density dependence of K'. These observations are inconsistent with the general equation P = KV alpha rho alpha-1 mu 2-alpha, where K is a constant related to airway geometry, rho is density and mu is viscosity. (Wood et al., J. Appl. Physiol. 41: 234-244, 1976). The reasons for this discrepancy are unclear, but do not appear to be related to effects of oscillatory flow because alpha was similar from 20 to 90 breaths/min in four subjects. We conclude that the curvilinearity of pulmonary pressure-flow curves is related to flow but independent of gas density and is not explicable solely on the basis of Reynolds' number.

Ventilatory Protective Strategies during Thoracic Surgery

2011 ◽  
Vol 114 (5) ◽  
pp. 1025-1035 ◽  
Author(s):  
Alf Kozian ◽  
Thomas Schilling ◽  
Hartmut Schütze ◽  
Mert Senturk ◽  
Thomas Hachenberg ◽  
...  
Keyword(s):  
Mechanical Stress ◽  
Lung Volume ◽  
Lung Ventilation ◽  
Alveolar Recruitment ◽  
Distribution Data ◽  
Dependent Lung ◽  
One Lung Ventilation ◽  
Lung Density ◽  
Computed Tomographic ◽  
Tidal Recruitment

Background The increased tidal volume (V(T)) applied to the ventilated lung during one-lung ventilation (OLV) enhances cyclic alveolar recruitment and mechanical stress. It is unknown whether alveolar recruitment maneuvers (ARMs) and reduced V(T) may influence tidal recruitment and lung density. Therefore, the effects of ARM and OLV with different V(T) on pulmonary gas/tissue distribution are examined. Methods Eight anesthetized piglets were mechanically ventilated (V(T) = 10 ml/kg). A defined ARM was applied to the whole lung (40 cm H(2)O for 10 s). Spiral computed tomographic lung scans were acquired before and after ARM. Thereafter, the lungs were separated with an endobronchial blocker. The pigs were randomized to receive OLV in the dependent lung with a V(T) of either 5 or 10 ml/kg. Computed tomography was repeated during and after OLV. The voxels were categorized by density intervals (i.e., atelectasis, poorly aerated, normally aerated, or overaerated). Tidal recruitment was defined as the addition of gas to collapsed lung regions. Results The dependent lung contained atelectatic (56 ± 10 ml), poorly aerated (183 ± 10 ml), and normally aerated (187 ± 29 ml) regions before ARM. After ARM, lung volume and aeration increased (426 ± 35 vs. 526 ± 69 ml). Respiratory compliance enhanced, and tidal recruitment decreased (95% vs. 79% of the whole end-expiratory lung volume). OLV with 10 ml/kg further increased aeration (atelectasis, 15 ± 2 ml; poorly aerated, 94 ± 24 ml; normally aerated, 580 ± 98 ml) and tidal recruitment (81% of the dependent lung). OLV with 5 ml/kg did not affect tidal recruitment or lung density distribution. (Data are given as mean ± SD.) Conclusions The ARM improves aeration and respiratory mechanics. In contrast to OLV with high V(T), OLV with reduced V(T) does not reinforce tidal recruitment, indicating decreased mechanical stress.

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