scholarly journals The influence of the post-pulmonary septum and submersion on the pulmonary mechanics of Trachemys scripta (Cryptodira: Emydidae)

2021 ◽  
Author(s):  
Ray Brasil Bueno de Souza ◽  
Wilfried Klein
Keyword(s):  
Hydrostatic Pressure ◽  
Respiratory System ◽  
Intact Animal ◽  
Work Of Breathing ◽  
Dynamic Compliance ◽  
Body Cavity ◽  
Trachemys Scripta ◽  
Pulmonary Mechanics ◽  
Static Compliance ◽  
Breathing Mechanics

The respiratory system of chelonians needs to function within a mostly solid carapace, with ventilation depending on movements of the flanks. When submerged, inspiration has to work against a hydrostatic pressure and we examined breathing mechanics in Trachemys scripta while underwater. Furthermore, the respiratory system of T. scripta possesses a well-developed post-pulmonary septum (PPS), and we investigated its role on breathing mechanics of lungs with and without their PPS attached. Static compliance was significantly increased in submerged animals and in animals with and without their PPS, while the removal of the PPS did not result in a significantly different static compliance. Dynamic compliance was significantly affected by changes in volume and frequency in every treatment, with submergence significantly decreasing dynamic compliance. The presence of the PPS significantly increased dynamic compliance. Submersion did not alter significantly work per ventilation, but caused minute work of breathing to be much greater at any frequency and ventilation level analyzed. Lungs with or without their PPS did not show significantly different work per ventilation when compared to intact animal. Our results demonstrate that submersion results in significantly altered breathing mechanics, increasing minute work of breathing greatly. The PPS was shown to maintain a constant volume within the animal's body cavity, wherein the lungs can be ventilated more easily, highlighting the importance of this coelomic subdivision in the chelonian body cavity.

Ontogeny of respiratory control and pulmonary mechanics in newborn rabbits

1985 ◽  
Vol 59 (5) ◽  
pp. 1477-1486 ◽  
Author(s):  
M. M. Grunstein ◽  
D. T. Tanaka
Keyword(s):  
Mechanical Properties ◽  
Tidal Volume ◽  
Respiratory System ◽  
Minute Ventilation ◽  
Work Of Breathing ◽  
Relative Volume ◽  
Respiratory Pattern ◽  
Pulmonary Mechanics ◽  
Volume Loss ◽  
Age Related

Maturation of the respiratory pattern and the active and passive mechanical properties of the respiratory system were assessed in 19 tracheotomized rabbits (postnatal age range: 1–26 days) placed in a body plethysmograph. With maturation both minute ventilation and tidal volume significantly increased, whereas respiratory frequency decreased. When normalized for body weight (kg) both the passive (Rrs X kg) and active (R'rs X kg) resistances of the respiratory system significantly increased with age, whereas the corresponding passive (Crs X kg-1) and active (C'rs X kg-1) compliances significantly decreased. At any given age R'rs X kg only slightly exceeded Rrs X kg, whereas C'rs X kg-1 was significantly lower than Crs X kg-1. Moreover, the maturational increases in Rrs X kg and R'rs X kg exceeded the corresponding decreases in Crs X kg-1 and C'rs X kg-1, resulting in significant age-related increases in both the passive (tau rs) and active (tau'rs) time constants of the respiratory system. Due to the age-related increases in tau'rs, producing a delayed volume response to any given inspiratory driving pressure, the relative volume loss obtained at any time during inspiration was greater in the maturing rabbit. On the other hand, because of concomitant compensatory changes in respiratory pattern, evidenced by increases in inspiratory duration with age, the end-inspiratory tidal volume loss in the maturing animal was maintained generally less than 10% at all postnatal ages. Thus maturational changes in respiratory pattern appear coupled to changes in the active mechanical properties of the respiratory system. The latter coupling serves to optimize the transduction of inspiratory pressure into volume change in a manner consistent with establishing the minimum inspiratory work of breathing during postnatal development.

scholarly journals Pulmonary Mechanics and the Work of Breathing in the Lizard, Gekko Gecko

1984 ◽  
Vol 113 (1) ◽  
pp. 187-202 ◽  
Author(s):  
WILLIAM K. MILSOM ◽  
TIMOTHY Z. VITALIS
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Minute Ventilation ◽  
Work Of Breathing ◽  
Body Cavity ◽  
The Body ◽  
Pulmonary Mechanics ◽  
Lung Inflation ◽  
Gekko Gecko ◽  
Tokay Gecko

Measurements of pulmonary mechanics made on anaesthetized specimens of the Tokay gecko Gekkogecko (Linné), indicate that both static and dynamic pulmonary mechanics are dominated by the mechanics of the body cavity and chest wall. The lungs are relatively large and compliant and offer little resistance to air flow at any of the ventilation frequencies (f) used in this study. The body wall is relatively stiff and becomes less compliant with increasing ventilation frequency and with increasing tidal volume (VT) at the higher frequencies. The vast majority of the work performed in breathing is used to overcome elastic forces in the chest wall resisting lung inflation. This work increases exponentially with increases in volume. As a consequence, in terms of total ventilation, the most economic breathing pattern is a high frequency, low tidal volume pattern in which changes in minute ventilation (VE) are most economically produced solely by changes in f. Because reductions in tidal volume drastically reduce alveolar ventilation volume while dead space remains constant, the same arguments do not apply to alveolar minute ventilation (VA). In terms of alveolar minute ventilation, there is an optimum combination of f and VT for each level of VA, with changes in VA being most economically produced by almost equal changes in both f and VT

scholarly journals Pulmonary Mechanics and the Work of Breathing in the Semi-Aquatic Turtle, Pseudemys Scripta

1986 ◽  
Vol 125 (1) ◽  
pp. 137-155 ◽  
Author(s):  
Timothy Z. Vitalis ◽  
William K. Milsom
Keyword(s):  
Body Wall ◽  
Striated Muscle ◽  
Work Of Breathing ◽  
Body Cavity ◽  
The Body ◽  
Mechanical Work ◽  
Pulmonary Mechanics ◽  
Pump Frequency ◽  
Elastic Forces ◽  
Pseudemys Scripta

Measurements of pulmonary mechanics on anaesthetized specimens of the aquatic turtle Pseudemys scripta (Schoepff) indicate that the static pulmonary mechanics of the total respiratory system are determined primarily by the mechanics of the body wall rather than those of the lungs. This is also true under the dynamic conditions of pump ventilation at low pump frequencies. As pump frequency increases, the work required to inflate the multicameral lungs of the turtle begins to contribute an increasing portion to the total mechanical work required to produce each breath as measured from pressure volume loops. The rise in the work performed on the lungs results from an increase in the non-elastic, flow-resistive forces which must be overcome during ventilation. The primary bronchus to each lung is the most likely site of flow resistance. There is also a small elastic component to the work required to ventilate the lungs associated with movement of the intrapulmonary septa and the striated muscle surrounding the lungs. The contribution of the work required to distend the body cavity as a percentage of the total mechanical work required to generate each breath remains relatively unchanged with increasing ventilation frequency, indicating that the majority of the forces to be overcome in the body wall are elastic in nature. For a constant rate of minute pump ventilation, as frequency increases, the work done per minute to overcome elastic forces decreases, while that done to overcome non-elastic forces begins to rise. These opposing trends produce an optimum combination of pump volume and frequency at which the rate of mechanical work is minimum.

Antenatal steroids, postnatal surfactant, and pulmonary function in premature rabbits

1989 ◽  
Vol 67 (4) ◽  
pp. 1377-1382 ◽  
Author(s):  
I. M. Gladstone ◽  
M. R. Mercurio ◽  
S. G. Devenny ◽  
H. C. Jacobs
Keyword(s):  
Pulmonary Function ◽  
Distress Syndrome ◽  
Pulmonary Function Tests ◽  
Dynamic Compliance ◽  
Pulmonary Mechanics ◽  
Static Compliance ◽  
Antenatal Corticosteroids ◽  
Antenatal Steroids ◽  
Lung Resistance ◽  
Total Lung Resistance

Antenatal corticosteroids reduce the incidence of the respiratory distress syndrome and improve pulmonary mechanics at least in part by mechanisms other than surfactant stimulation. We measured several aspects of pulmonary function in rabbits to better understand the mechanisms involved. Seven does were given intramuscular betamethasone and six were given vehicle on days 25 and 26 of gestation. Delivery was on day 27 (term = 31). Half of the fetuses from each litter were given rabbit surfactant before the first breath. All fetuses were then ventilated at a consistent tidal volume for 1 h. Pulmonary function tests included static and dynamic compliance, expiratory time constant, stress relaxation, total lung resistance, and total lung conductance. Steroid or surfactant treatment increased dynamic compliance, and the effects of both together were greater than either alone. Static compliance was affected more by surfactant than steroids, whereas lung resistance and conductance were affected more by steroids. The differences in action of the two therapies help account for the increased dynamic compliance seen with combination therapy.

scholarly journals Broad individual immersion-scattering of respiratory compliance likely substantiates dissimilar breathing mechanics

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Olivier Castagna ◽  
Guillaume Michoud ◽  
Thibaut Prevautel ◽  
Antoine Delafargue ◽  
Bruno Schmid ◽  
...  
Keyword(s):  
Respiratory System ◽  
Water Immersion ◽  
Work Of Breathing ◽  
Adult Group ◽  
Respiratory Compliance ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Diving Medicine ◽  
Breathing Mechanics ◽  
Diverse Individual

AbstractHead-out water immersion alters respiratory compliance which underpins defining pressure at a “Lung centroid” and the breathing “Static Lung Load”. In diving medicine as in designing dive-breathing devices a single value of lung centroid pressure is presumed as everyone’s standard. On the contrary, we considered that immersed respiratory compliance is disparate among a homogenous adult group (young, healthy, sporty). We wanted to substantiate this ample scattering for two reasons: (i) it may question the European standard used in designing dive-breathing devices; (ii) it may contribute to understand the diverse individual figures of immersed work of breathing. Resting spirometric measurements of lung volumes and the pressure–volume curve of the respiratory system were assessed for 18 subjects in two body positions (upright Up, and supine Sup). Measurements were taken in air (Air) and with subjects immersed up to the sternal notch (Imm). Compliance of the respiratory system (Crs) was calculated from pressure–volume curves for each condition. A median 60.45% reduction in Crs was recorded between Up-Air and Up-Imm (1.68 vs 0.66 L/kPa), with individual reductions ranging from 16.8 to 82.7%. We hypothesize that the previously disregarded scattering of immersion-reduced respiratory compliance might participate to substantial differences in immersed work of breathing.

Changes in compliance in rabbits subjected to acute bronchoconstriction

1963 ◽  
Vol 18 (3) ◽  
pp. 539-543 ◽  
Author(s):  
Nicholas R. Anthonisen
Keyword(s):  
Functional Residual Capacity ◽  
Pulmonary Circulation ◽  
Dynamic Compliance ◽  
Pulmonary Mechanics ◽  
Static Compliance ◽  
Airway Occlusion ◽  
Random Direction ◽  
Residual Capacity ◽  
Spontaneously Breathing ◽  
Phrenic Stimulation

The pulmonary mechanics of anesthetized rabbits were studied during induced acute bronchoconstriction. The bronchoconstricting agent was acetyl-β-methylcholine which, when injected intravenously as in these experiments, appeared to act via the pulmonary circulation. In spontaneously breathing animals functional residual capacity increased with bronchospasm, and dynamic compliance decreased. This decrease correlated in magnitude with the severity of the bronchoconstriction. Frequency changed in random direction. Dynamic compliance recovered more slowly than conductance after bronchoconstriction unless the lungs were inflated just prior to each recovery measurement, in which case the two variables recovered equally quickly. This observation suggested that airway occlusion accounted for part of the decrease in dynamic compliance. Bronchoconstriction reduced semistatic compliance in paralyzed artificially ventilated animals and also static compliance, which was measured by arresting breathing with phrenic stimulation, in spontaneously breathing animals. These observations supported the above hypothesis. Submitted on September 26, 1962

Mortality and pulmonary mechanics in relation to respiratory system and transpulmonary driving pressures in ARDS

2016 ◽  
Vol 42 (8) ◽  
pp. 1206-1213 ◽  
Author(s):  
Elias Baedorf Kassis ◽  
Stephen H. Loring ◽  
Daniel Talmor
Keyword(s):  
Respiratory System ◽  
Pulmonary Mechanics

Mechanics of respiratory system in healthy anesthetized humans with emphasis on viscoelastic properties

1993 ◽  
Vol 75 (1) ◽  
pp. 132-140 ◽  
Author(s):  
B. Jonson ◽  
L. Beydon ◽  
K. Brauer ◽  
C. Mansson ◽  
S. Valind ◽  
...  
Keyword(s):  
Respiratory System ◽  
Driving Force ◽  
Viscoelastic Behavior ◽  
Elastic Recoil ◽  
Inspiratory Flow Rate ◽  
Static Compliance ◽  
Viscoelastic System ◽  
Flow Interruption ◽  
In Series ◽  
Flow Dependency

The classic model of the respiratory system (RS) is comprised of a Newtonian resistor in series with a capacitor and a viscoelastic unit including a resistor and a capacitor. The flow interruption technique has often been used to study the viscoelastic behavior under constant inspiratory flow rate. To study the viscoelastic behavior of the RS during complete respiratory cycles and to quantify viscoelastic resistance (Rve) and compliance (Cve) under unrestrained conditions, we developed an iterative technique based on a differential equation. We, as others, assumed Rve and Cve to be constant, which concords with volume and flow dependency of model behavior. During inspiration Newtonian resistance (R) was independent of flow and volume. During expiration R increased. Static elastic recoil showed no significant hysteresis. The viscoelastic behavior of the RS was in accordance with the model. The magnitude of Rve was 3.7 +/- 0.7 cmH2O.l-1 x s, i.e., two times R. Cve was 0.23 +/- 0.051 l/cmH2O, i.e., four times static compliance. The viscoelastic time constant, i.e., Cve.Rve, was 0.82 +/- 0.11s. The work dissipated against the viscoelastic system was 0.62 +/- 0.13 cmH2O x 1 for a breath of 0.56 liter, corresponding to 32% of the total energy loss within the RS. Viscoelastic recoil contributed as a driving force during the initial part of expiration.

scholarly journals Respiratory Care for the Ventilated Neonate

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Gustavo Rocha ◽  
Paulo Soares ◽  
Américo Gonçalves ◽  
Ana Isabel Silva ◽  
Diana Almeida ◽  
...  
Keyword(s):  
Near Infrared ◽  
Periventricular Leukomalacia ◽  
Work Of Breathing ◽  
Newborn Infants ◽  
Pulmonary Hemorrhage ◽  
Added Value ◽  
Respiratory Care ◽  
Pulmonary Mechanics ◽  
Airway Caliber ◽  
Ventilation Modes

Invasive ventilation is often necessary for the treatment of newborn infants with respiratory insufficiency. The neonatal patient has unique physiological characteristics such as small airway caliber, few collateral airways, compliant chest wall, poor airway stability, and low functional residual capacity. Pathologies affecting the newborn’s lung are also different from many others observed later in life. Several different ventilation modes and strategies are available to optimize mechanical ventilation and to prevent ventilator-induced lung injury. Important aspects to be considered in ventilating neonates include the use of correct sized endotracheal tube to minimize airway resistance and work of breathing, positioning of the patient, the nursing care, respiratory kinesiotherapy, sedation and analgesia, and infection prevention, namely, the ventilator-associated pneumonia and nosocomial infection, as well as prevention and treatment of complications such as air leaks and pulmonary hemorrhage. Aspects of ventilation in patients under ECMO (extracorporeal membrane oxygenation) and in palliative care are of increasing interest nowadays. Online pulmonary mechanics and function testing as well as capnography are becoming more commonly used. Echocardiography is now a routine in most neonatal units. Near infrared spectroscopy (NIRS) is an attractive tool potentially helping in preventing intraventricular hemorrhage and periventricular leukomalacia. Lung ultrasound is an emerging tool of diagnosis and can be of added value in helping monitoring the ventilated neonate. The aim of this scientific literature review is to address relevant aspects concerning the respiratory care and monitoring of the invasively ventilated newborn in order to help physicians to optimize the efficacy of care.

Elevated static compliance of the total respiratory system: Early predictor of weaning unsuccess in severe COPD patients mechanically ventilated

1995 ◽  
Vol 21 (5) ◽  
pp. 399-405 ◽  
Author(s):  
E. Zanotti ◽  
F. Rubini ◽  
G. Iotti ◽  
A. Braschi ◽  
A. Palo ◽  
...  
Keyword(s):  
Respiratory System ◽  
Static Compliance ◽  
Mechanically Ventilated ◽  
Copd Patients ◽  
Early Predictor ◽  
Severe Copd
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