The bimodal quasi-static and dynamic elastance of the murine lung

2008 ◽  
Vol 105 (2) ◽  
pp. 685-692 ◽  
Author(s):  
Graeme R. Zosky ◽  
Tibor Z. Janosi ◽  
Ágnes Adamicza ◽  
Elizabeth M. Bozanich ◽  
Vincenzo Cannizzaro ◽  
...  
Keyword(s):  
Lung Volume ◽  
Lung Mechanics ◽  
Mouse Lung ◽  
Forced Oscillation Technique ◽  
Mechanically Ventilated ◽  
Thoracic Gas Volume ◽  
Residual Capacity ◽  
Gas Volume ◽  
Tissue Elastance

The double sigmoidal nature of the mouse pressure-volume (PV) curve is well recognized but largely ignored. This study systematically examined the effect of inflating the mouse lung to 40 cm H2O transrespiratory pressure (Prs) in vivo. Adult BALB/c mice were anesthetized, tracheostomized, and mechanically ventilated. Thoracic gas volume was calculated using plethysmography and electrical stimulation of the intercostal muscles. Lung mechanics were tracked during inflation-deflation maneuvers using a modification of the forced oscillation technique. Inflation beyond 20 cm H2O caused a shift in subsequent PV curves with an increase in slope of the inflation limb and an increase in lung volume at 20 cm H2O. There was an overall decrease in tissue elastance and a fundamental change in its volume dependence. This apparent “softening” of the lung could be recovered by partial degassing of the lung or applying a negative transrespiratory pressure such that lung volume decreased below functional residual capacity. Allowing the lung to spontaneously recover revealed that the lung required ∼1 h of mechanical ventilation to return to the original state. We propose a number of possible mechanisms for these observations and suggest that they are most likely explained by the unfolding of alveolar septa and the subsequent redistribution of the fluid lining the alveoli at high transrespiratory pressure.

Measurement of high lung volumes by nitrogen washout method

1994 ◽  
Vol 77 (3) ◽  
pp. 1562-1564 ◽  
Author(s):  
Y. Sivan ◽  
J. Hammer ◽  
C. J. Newth
Keyword(s):  
Lung Volume ◽  
Human Infants ◽  
Lung Volumes ◽  
Nitrogen Washout ◽  
Thoracic Gas Volume ◽  
Residual Capacity ◽  
The Difference ◽  
Gas Dilution ◽  
Spontaneously Breathing ◽  
Gas Volume

Studies on human infants suggested that thoracic gas volume (TGV) measured at end exhalation may not depict the true TGV and may differ from TGV measured from a series of higher lung volumes and corrected for the volume added. This was explained by gas trapping. If true, we should expect the discrepancy to be more pronounced when functional residual capacity (FRC) and higher lung volumes are measured by gas dilution techniques. We studied lung volumes above FRC by the nitrogen washout technique in 12 spontaneously breathing rhesus monkeys (5.0–11.3 kg wt; 42 compared measurements). Lung volumes directly measured were compared with preset lung volumes achieved by artificial inflation of the lungs above FRC with known volumes of air (100–260 ml). Measured lung volume strongly correlated with and was not significantly different from present lung volume (P = 0.05; r = 0.996). The difference between measured and preset lung volume was 0–5% in 41 of 42 cases [1 +/- 0.4% (SE)]. The direction of the difference was unpredictable; in 22 of 42 cases the measured volume was larger than the preset volume, but in 17 of 42 cases it was smaller. The difference was not affected by the volume of gas artificially inflated into the lungs. We conclude that, overall, lung volumes above FRC can be reliably measured by the nitrogen washout technique and that FRC measurements by this method reasonably reflect true FRC.

Critical assessment of jacket plethysmographs for use in young children

1982 ◽  
Vol 52 (1) ◽  
pp. 267-273 ◽  
Author(s):  
P. Helms ◽  
B. W. Taylor ◽  
A. D. Milner ◽  
D. J. Hatch
Keyword(s):  
Young Children ◽  
Respiratory Function Tests ◽  
Lung Mechanics ◽  
Positive Pressure ◽  
Tidal Breathing ◽  
Thoracic Gas Volume ◽  
Young Subjects ◽  
Gas Volume

In infants and very young children changes in thoracic gas volume (Vtg) during tidal breathing and during intermittent positive-pressure lung inflations have been estimated from pressure changes within double-layered rubber jackets covering the thorax and abdomen. In vitro and in vivo assessments demonstrated the linearity of these jackets over the range of volume changes found in these young subjects during respiratory function tests, and the small intrajacket background pressure (2.5 cmH2O) had minimal effects on resting lung volume and lung mechanics. These jackets can be used to monitor tidal volume in quiet subjects, and if an intermittent positive-pressure inflation technique is used static compliance can be accurately measured. The hysteresis of natural rubber and the direct contact of the recording system with the subject renders it unsuitable for the measurement of lung mechanics during tidal breathing and for the estimation of Vtg during airway occlusions.

Static lung mechanics of intact and excised rhesus monkey lungs and lobes

1978 ◽  
Vol 44 (4) ◽  
pp. 547-552 ◽  
Author(s):  
P. D. Pare ◽  
R. Boucher ◽  
M. C. Michoud ◽  
J. C. Hogg
Keyword(s):  
Lung Volume ◽  
Transpulmonary Pressure ◽  
Lung Mechanics ◽  
Unit Weight ◽  
Water Displacement ◽  
Lung Capacity ◽  
Residual Capacity ◽  
Boyle’S Law

Subdivisions of lung volume and pressure-volume (PV) curves of the lung and chest wall (CW) were measured in 12 rhesus monkeys (Macacca mulatta) under pentobarbital anesthesia. In addition, volumes and PV curves were obtained on the excised lungs and lobes of 12 cynomolgus monkeys (M. fasicularis). Boyle's law was used to determine functional residual capacity (FRC) in the intact animals and water displacement to determine minimal volume (MV) in the excised lungs. Total lung capacity (TLC = lung volume at a transpulmonary pressure of 30 cmH2O) was similar in vivo and in vitro (90 + 83 ml/kg) but residual volume (RV = volume at airway pressure of -50 cmH2O) and MV differed markedly (16.5 + 5.9 ml/kg). In the intact animals a very stiff CW appeared to determine RV, whereas airway closure determined MV in excised lungs. PV curves of upper and lower lobes were not different when expressed as %TLC but when expressed as milliliters of gas per gram of lung, the upper lobes contained significantly more gas per unit weight.

Plethysmographic estimation of thoracic gas volume in apneic mice

2006 ◽  
Vol 101 (2) ◽  
pp. 454-459 ◽  
Author(s):  
Tibor Z. Jánosi ◽  
Ágnes Adamicza ◽  
Graeme R. Zosky ◽  
Tibor Asztalos ◽  
Peter D. Sly ◽  
...  
Keyword(s):  
Oxygen Mixture ◽  
Lung Inflation ◽  
Mechanically Ventilated ◽  
Airway Occlusion ◽  
Thoracic Gas Volume ◽  
Before And After ◽  
Residual Capacity ◽  
Breathing Effort ◽  
Gas Volume ◽  
Good Agreement

Electrical stimulation of intercostal muscles was employed to measure thoracic gas volume (TGV) during airway occlusion in the absence of respiratory effort at different levels of lung inflation. In 15 tracheostomized and mechanically ventilated CBA/Ca mice, the value of TGV obtained from the spontaneous breathing effort available in the early phase of the experiments (TGVsp) was compared with those resulting from muscle stimulation (TGVst) at transrespiratory pressures of 0, 10, and 20 cmH2O. A very strong correlation ( r2 = 0.97) was found, although with a systematically (∼16%) higher estimation of TGVst relative to TGVsp, attributable to the different durations of the stimulated (∼50 ms) and spontaneous (∼200 ms) contractions. Measurements of TGVst before and after injections of 0.2, 0.4, and 0.6 ml of nitrogen into the lungs in six mice resulted in good agreement between the change in TGVst and the injected volume ( r2 = 0.98). In four mice, TGVsp and TGVst were compared at end expiration with air or a helium-oxygen mixture to confirm the validity of isothermal compression in the alveolar gas. The TGVst values measured at zero transrespiratory pressure in all CBA/Ca mice [0.29 ± 0.05 (SD) ml] and in C57BL/6 ( N = 6; 0.34 ± 0.08 ml) and BALB/c ( N = 6; 0.28 ± 0.06 ml) mice were in agreement with functional residual capacity values from previous studies in which different techniques were used. This method is particularly useful when TGV is to be determined in the absence of breathing activity, when it must be known at any level of lung inflation or under non-steady-state conditions, such as during pharmaceutical interventions.

Pulmonary response to threshold levels of sulfur dioxide (1.0 ppm) and ozone (0.3 ppm)

1985 ◽  
Vol 58 (6) ◽  
pp. 1783-1787 ◽  
Author(s):  
L. J. Folinsbee ◽  
J. F. Bedi ◽  
S. M. Horvath
Keyword(s):  
Sulfur Dioxide ◽  
Pulmonary Response ◽  
Rest Periods ◽  
Pollutant Concentrations ◽  
Thoracic Gas Volume ◽  
Exercise Ventilation ◽  
Before And After ◽  
Residual Capacity ◽  
Gas Volume ◽  
Male Subjects

We exposed 22 healthy adult nonsmoking male subjects for 2 h to filtered air, 1.0 ppm sulfur dioxide (SO2), 0.3 ppm ozone (O3), or the combination of 1.0 ppm SO2 + 0.3 ppm O3. We hypothesized that exposure to near-threshold concentrations of these pollutants would allow us to observe any interaction between the two pollutants that might have been masked by the more obvious response to the higher concentrations of O3 used in previous studies. Each subject alternated 30-min treadmill exercise with 10-min rest periods for the 2 h. The average exercise ventilation measured during the last 5 min of exercise was 38 1/min (BTPS). Forced expiratory maneuvers were performed before exposure and 5 min after each of the three exercise periods. Maximum voluntary ventilation, He dilution functional residual capacity, thoracic gas volume, and airway resistance were measured before and after the exposure. After O3 exposure alone, forced expiratory measurements (FVC, FEV1.0, and FEF25–75%) were significantly decreased. The combined exposure to SO2 + O3 produced similar but smaller decreases in these measures. There were small but significant differences between the O3 and the O3 + SO2 exposure for FVC, FEV1.0, FEV2.0, FEV3.0, and FEF25–75% at the end of the 2-h exposure. We conclude that, with these pollutant concentrations, there is no additive or synergistic effect of the two pollutants on pulmonary function.

scholarly journals Lung volumes and respiratory mechanics in elastase-induced emphysema in mice

2008 ◽  
Vol 105 (6) ◽  
pp. 1864-1872 ◽  
Author(s):  
Z. Hantos ◽  
Á. Adamicza ◽  
T. Z. Jánosi ◽  
M. V. Szabari ◽  
J. Tolnai ◽  
...  
Keyword(s):  
Mouse Model ◽  
Low Frequency ◽  
Forced Oscillations ◽  
Mechanical Parameters ◽  
Tissue Destruction ◽  
Lung Volumes ◽  
Lung Capacity ◽  
Thoracic Gas Volume ◽  
Residual Capacity ◽  
Gas Volume

Absolute lung volumes such as functional residual capacity, residual volume (RV), and total lung capacity (TLC) are used to characterize emphysema in patients, whereas in animal models of emphysema, the mechanical parameters are invariably obtained as a function of transrespiratory pressure (Prs). The aim of the present study was to establish a link between the mechanical parameters including tissue elastance (H) and airway resistance (Raw), and thoracic gas volume (TGV) in addition to Prs in a mouse model of emphysema. Using low-frequency forced oscillations during slow deep inflation, we tracked H and Raw as functions of TGV and Prs in normal mice and mice treated with porcine pancreatic elastase. The presence of emphysema was confirmed by morphometric analysis of histological slices. The treatment resulted in an increase in TGV by 51 and 44% and a decrease in H by 57 and 27%, respectively, at 0 and 20 cmH2O of Prs. The Raw did not differ between the groups at any value of Prs, but it was significantly higher in the treated mice at comparable TGV values. In further groups of mice, tracheal sounds were recorded during inflations from RV to TLC. All lung volumes but RV were significantly elevated in the treated mice, whereas the numbers and size distributions of inspiratory crackles were not different, suggesting that the airways were not affected by the elastase treatment. These findings emphasize the importance of absolute lung volumes and indicate that tissue destruction was not associated with airway dysfunction in this mouse model of emphysema.

ALVEOLAR-ARTERIAL O2 AND CO2 DIFFERENCES AND THEIR RELATION TO LUNG VOLUME IN THE NEWBORN

PEDIATRICS ◽  
1968 ◽  
Vol 41 (3) ◽  
pp. 574-587 ◽  
Author(s):  
D. W. Thibeault ◽  
E. Poblete ◽  
P. A. M. Auld
Keyword(s):  
Carbon Dioxide ◽  
Premature Infants ◽  
Lung Volume ◽  
Term Infant ◽  
Full Term ◽  
Arterial Oxygen ◽  
Term Infants ◽  
Oxygen Gradient ◽  
Thoracic Gas Volume ◽  
Gas Volume

Twenty-six premature and five full-term infants, ranging in birth weight from 860 to 4,040 gm and in age from 3 hours to 98 days, were the subjects of this study. Measurements of thoracic gas volume and determination of alveolar-arterial oxygen gradient and arterial-alveolar carbon dioxide gradient were performed. All infants showed a decrease in thoracic gas volume in the first days of life. The initial high thoracic gas volume is thought to be due to trapped gas. The ability to trap gas was demonstrated in a number of infants. In the full-term infant the decrease in thoracic gas volume is associated with improvement in lung function. In the premature infants the decrease in lung volume is associated with a persistently elevated alveolar-arterial oxygen gradient and in an inequality of perfusion and ventilation, as evidenced by the large arterial-alveolar carbon dioxide gradient. In a small group of infants increase in functional residual capacity produced by negative pressure around the chest resulted in a decrease in the carbon dioxide and oxygen gradients, indicating that the infant's lung volume is less than optimum. These observations characterize in physiological terms some of the respiratory difficulties in small premature infants.

Determinants of forced expiratory flows in newborn infants

1982 ◽  
Vol 53 (5) ◽  
pp. 1220-1227 ◽  
Author(s):  
L. M. Taussig ◽  
L. I. Landau ◽  
S. Godfrey ◽  
I. Arad
Keyword(s):  
Newborn Infants ◽  
Cross Sectional Area ◽  
Physiological Data ◽  
Sectional Area ◽  
Older Children ◽  
Cross Sectional ◽  
Thoracic Gas Volume ◽  
Residual Capacity ◽  
The Cross ◽  
Gas Volume

Maximal flows at functional residual capacity (VmaxFRC) from partial expiratory flow-volume (PEFV) curves (achieved with rapid compression of the chest) were obtained on 11 healthy newborn babies. Mean VmaxFRC, size corrected by dividing absolute values by measured thoracic gas volume, was 1.90 TGV's/s. Specific upstream conductances were high, and the cross-sectional area of the flow-limiting segment was estimated to be approximately 0.30 cm2 in the three infants on whom recoil pressures at FRC were also measured. The cross-sectional area of the major bronchi in the neonate is approximately 0.26–0.30 cm2. PEFV curves were convex to the volume axis. Many of the neonates increased their flows while breathing a helium-oxygen gas mixture. These results suggest 1) size-corrected flows are higher in the neonate than in older children or adults; 2) the site of the flow-limiting segment at FRC during maximal expiratory maneuvers is in large proximal airways, similar to the adult; and 3) the relationship of airway size to parenchymal size may be similar in neonates and adults or, in fact, airways may be larger, relative to parenchyma, in neonates. These physiological data do not support the hypothesis, based on pathological studies, that peripheral airways are disproportionately smaller (when compared with central airways) in infants than in adults.

Problems in measurement of thoracic gas volume in infancy

1982 ◽  
Vol 52 (4) ◽  
pp. 995-999 ◽  
Author(s):  
C. S. Beardsmore ◽  
J. Stocks ◽  
M. Silverman
Keyword(s):  
Functional Residual Capacity ◽  
Clinical Status ◽  
Pleural Pressure ◽  
Whole Body ◽  
Airway Closure ◽  
Lung Volumes ◽  
Airway Occlusion ◽  
Thoracic Gas Volume ◽  
Residual Capacity ◽  
Gas Volume

Thoracic gas volume (TGV) was measured with a whole-body plethysmograph in 20 infants at functional residual capacity (FRC) and at a series of higher lung volumes achieved by artificial inflation of the lungs with known volumes of air after airway occlusion. There was a discrepancy between the corrected values of TGV measured at high and low lung volumes in nine infants; in six cases TGV measured at high lung volumes exceeded that measured at FRC, and in three cases it was reduced when compared with the measurement made at FRC. These changes were not related to age, size, or clinical status and could be explained by airway closure at FRC, combined with an uneven distribution of pleural pressure.

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