scholarly journals LUNG VOLUME, TIDAL VOLUME, AND ALVEOLAR PRESSURE DURING JET VENTILATION

1984 ◽  
Vol 18 ◽  
pp. 391A-391A
Author(s):  
Ivan D Frantz ◽  
Richard H Close
Keyword(s):  
Tidal Volume ◽  
Lung Volume ◽  
Alveolar Pressure ◽  
Jet Ventilation

Mean airway pressure and alveolar pressure during high-frequency ventilation

1984 ◽  
Vol 57 (4) ◽  
pp. 1069-1078 ◽  
Author(s):  
B. A. Simon ◽  
G. G. Weinmann ◽  
W. Mitzner
Keyword(s):  
Tidal Volume ◽  
Lung Volume ◽  
High Frequency ◽  
Airway Pressure ◽  
High Frequency Ventilation ◽  
Alveolar Pressure ◽  
Mean Flow ◽  
Mean Airway Pressure ◽  
Expiratory Flow Limitation ◽  
Frequency Ventilation

Studies and applications of high-frequency ventilation (HFV) are often performed under conditions of controlled mean airway pressure (Paw). In the present study we tested the assumption that controlling Paw adequately controls lung volume during HFV by investigating the relationship between a reliably measured Paw and the mean alveolar pressure (Palv) of the lungs during HFV of healthy dogs. We minimized the errors of Paw measurement due to the Bernoulli effect and various technical factors by appropriate choice of transducers, amplifiers, and measurement site. Palv was estimated by clamping the ventilator tube during oscillation and measuring the equilibration pressure of the lung and airways. Paw and Palv were determined as functions of frequency (8–25 Hz), tidal volume (60–90 ml), Paw (-5 to 12 cmH2O), and position of the animal (supine vs. lateral). We found that Paw could significantly underestimate Palv and that the degree of underestimation increased at higher frequencies, larger tidal volumes, and lower Paw. Shifting the animal from the supine to the lateral position greatly accentuated this effect. The elevation of Palv above Paw was seen to be a function of mean flow and largely independent of the frequency-tidal volume combination which produced the flow. A possible explanation of this pressure difference is that it results from differences in inspiratory and expiratory airway impedances, which in turn depend on airway geometry, compliance, lung volume, and expiratory flow limitation.

Effect of lung volume on plateau response of airways and tissue to methacholine in dogs

1992 ◽  
Vol 73 (5) ◽  
pp. 1908-1913 ◽  
Author(s):  
F. M. Robatto ◽  
S. Simard ◽  
H. Orana ◽  
P. T. Macklem ◽  
M. S. Ludwig
Keyword(s):  
Pressure Drop ◽  
Tidal Volume ◽  
Lung Volume ◽  
Airway Resistance ◽  
Positive End Expiratory Pressure ◽  
Alveolar Pressure ◽  
Lung Elastance ◽  
Tissue Resistance ◽  
Airway Caliber ◽  
Lung Resistance

We have recently shown in dogs that much of the increase in lung resistance (RL) after induced constriction can be attributed to increases in tissue resistance, the pressure drop in phase with flow across the lung tissues (Rti). Rti is dependent on lung volume (VL) even after induced constriction. As maximal responses in RL to constrictor agonists can also be affected by changes in VL, we questioned whether changes in the plateau response with VL could be attributed in part to changes in the resistive properties of lung tissues. We studied the effect of changes in VL on RL, Rti, airway resistance (Raw), and lung elastance (EL) during maximal methacholine (MCh)-induced constriction in 8 anesthetized, paralyzed, open-chest mongrel dogs. We measured tracheal flow and pressure (Ptr) and alveolar pressure (PA), the latter using alveolar capsules, during tidal ventilation [positive end-expiratory pressure (PEEP) = 5.0 cmH2O, tidal volume = 15 ml/kg, frequency = 0.3 Hz]. Measurements were recorded at baseline and after the aerosolization of increasing concentrations of MCh until a clear plateau response had been achieved. VL was then altered by changing PEEP to 2.5, 7.5, and 10 cmH2O. RL changed only when PEEP was altered from 5 to 10 cmH2O (P < 0.01). EL changed when PEEP was changed from 5 to 7.5 and 5 to 10 cmH2O (P < 0.05). Rti and Raw varied significantly with all three maneuvers (P < 0.05). Our data demonstrate that the effects of VL on the plateau response reflect a complex combination of changes in tissue resistance, airway caliber, and lung recoil.

scholarly journals 1858 DETERMINANTS OF TIDAL VOLUME (VT) DURING HIGH'S-FREQUENCY JET VENTILATION(HFJV)

1985 ◽  
Vol 19 (4) ◽  
pp. 420A-420A
Author(s):  
S A Weisberger ◽  
W A Carlo ◽  
J M Fouke ◽  
R L Chatburn ◽  
T Tillander ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Jet Ventilation

Expiratory muscle contribution to tidal volume in head-up dogs

1989 ◽  
Vol 67 (4) ◽  
pp. 1438-1442 ◽  
Author(s):  
G. A. Farkas ◽  
M. Estenne ◽  
A. De Troyer
Keyword(s):  
Tidal Volume ◽  
Lung Volume ◽  
Muscle Relaxation ◽  
Rib Cage ◽  
Expiratory Muscle ◽  
Residual Capacity ◽  
Anesthetized Dogs ◽  
Expiratory Muscles ◽  
S Period ◽  
Average Contribution

A change from the supine to the head-up posture in anesthetized dogs elicits increased phasic expiratory activation of the rib cage and abdominal expiratory muscles. However, when this postural change is produced over a 4- to 5-s period, there is an initial apnea during which all the muscles are silent. In the present studies, we have taken advantage of this initial silence to determine functional residual capacity (FRC) and measure the subsequent change in end-expiratory lung volume. Eight animals were studied, and in all of them end-expiratory lung volume in the head-up posture decreased relative to FRC [329 +/- 70 (SE) ml]. Because this decrease also represents the increase in lung volume as a result of expiratory muscle relaxation at the end of the expiratory pause, it can be used to determine the expiratory muscle contribution to tidal volume (VT). The average contribution was 62 +/- 6% VT. After denervation of the rib cage expiratory muscles, the reduction in end-expiratory lung volume still amounted to 273 +/- 84 ml (49 +/- 10% VT). Thus, in head-up dogs, about two-thirds of VT result from the action of the expiratory muscles, and most of it (83%) is due to the action of the abdominal rather than the rib cage expiratory muscles.

Expiratory flow limitation during exercise in prepubescent boys and girls: prevalence and implications

2010 ◽  
Vol 108 (5) ◽  
pp. 1267-1274 ◽  
Author(s):  
Katherine E. Swain ◽  
Sara K. Rosenkranz ◽  
Bethany Beckman ◽  
Craig A. Harms
Keyword(s):  
Body Composition ◽  
Oxygen Saturation ◽  
Tidal Volume ◽  
Lean Body Mass ◽  
Lung Volume ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Expiratory Flow

The purpose of this study was to compare the prevalence and implications of expiratory flow limitation (EFL) during exercise in boys and girls. Forty healthy, prepubescent boys (B; n = 20) and girls (G; n = 20) were tested. Subjects completed pulmonary function tests and an incremental cycle maximal oxygen uptake (V̇o2max) test. EFL was recorded at the end of each exercise stage using the % tidal volume overlap method. Ventilatory and metabolic data were recorded throughout exercise. Arterial oxygen saturation (SpO2) was determined via pulse oximetry. Body composition was determined using dual-energy X-ray absorptiometry. There were no differences ( P > 0.05) in height, weight, or body composition between boys and girls. At rest, boys had significantly higher lung volumes (total lung capacity, B = 2.6 ± 0.5 liters, G = 2.1 ± 0.5 liters) and peak expiratory flow rates (B = 3.6 ± 0.6 l/s; G = 1.6 ± 0.3 l/s). Boys also had significantly higher V̇o2max (B = 46.9 ± 5.9 ml·kg lean body mass−1·min−1, G = 41.7 ± 6.6 ml·kg lean body mass−1·min−1) and maximal ventilation (B = 49.8 ± 8.8 l/min, G = 41.2 ± 8.3 l/min) compared with girls. There were no sex differences ( P > 0.05) at V̇o2max in VE /Vco2, end-tidal Pco2, heart rate, respiratory exchange ratio, or SpO2. The prevalence (B = 19/20 vs. G = 18/20) and severity (B = 58 ± 7% vs. G = 43 ± 8% tidal volume) of EFL was not significantly different in boys compared with girls at V̇o2max. A significant relationship existed between % EFL at V̇o2max and the change in end-expiratory lung volume from rest to maximal exercise in boys ( r = 0.77) and girls ( r = 0.75). In summary, our data suggests that EFL is highly and equally prevalent in prepubescent boys and girls during heavy exercise, which led to an increased end-expiratory lung volume but not to decreases in arterial oxygen saturation.

Changes in respiratory muscle activity in ponies when end-expiratory lung volume is increased

1994 ◽  
Vol 76 (5) ◽  
pp. 2015-2025 ◽  
Author(s):  
B. K. Erickson ◽  
H. V. Forster ◽  
T. F. Lowry ◽  
L. G. Pan ◽  
M. J. Korducki ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Lung Volume ◽  
Negative Pressure ◽  
Muscle Activity ◽  
Respiratory Muscle ◽  
Transversus Abdominis ◽  
Vagal Afferents ◽  
Breathing Frequency ◽  
Respiratory Muscle Activity

The objective of the present study was to determine whether lung and diaphragm afferents contribute to the changes in respiratory muscle activity when end-expiratory lung volume (EELV) is changed in ponies. We studied the responses of the diaphragm and the transversus abdominis (TA) muscles to passive increases in EELV in awake intact (I), diaphragm-deafferented (DD), pulmonary vagal- (hilar nerve) denervated (HND), and DD + HND ponies. Negative pressure of -10 or -20 cmH2O applied around the ponies′ torsos [positive transrespiratory (TR) pressure] increased (P < 0.05) EELV in all ponies; the increases were more (P < 0.05) in HND and less (P < 0.05) in DD than in I ponies. In I ponies, positive TR pressure increased (P < 0.05) the rate of rise of the integrated diaphragmatic electromyogram (EMG), reflecting increased drive to the muscle. This increase was less (P < 0.05) in DD and HND than in I ponies. In DD + HND ponies, there was no significant (P > 0.10) change in drive to the diaphragm during positive TR pressure. In I ponies, positive TR pressure increased (P < 0.05) the duration and mean activity of the TA EMG. In HND and DD + HND ponies, the TA EMG was not altered by positive TR pressure. I and DD ponies decreased (P < 0.05) breathing frequency but maintained tidal volume (VT) during positive TR pressure. HND and DD+HND ponies increased breathing frequency (P < 0.05) and decreased (P < 0.05) VT during positive TR pressure. We conclude that, during positive TR pressure when the diaphragm is presumably at a mechanical disadvantage, diaphragm and vagal afferents mediate increased drive to the diaphragm to prevent VT from decreasing. In addition, during positive TR pressure, vagal afferents mediate an increase in duration of TA activity, which minimizes the increase in EELV.

Alveolar pressure and lung volume as determinants of net transvascular fluid filtration

1977 ◽  
Vol 42 (4) ◽  
pp. 476-482 ◽  
Author(s):  
G. Bo ◽  
A. Hauge ◽  
G. Nicolaysen
Keyword(s):  
Lung Volume ◽  
Continuous Monitoring ◽  
Interstitial Fluid ◽  
Positive Airway Pressure ◽  
Fluid Pressure ◽  
Alveolar Pressure ◽  
Experimental Conditions ◽  
Fluid Filtration ◽  
Pulmonary Arterial ◽  
Relative Change

We have investigated the influence of changes in alveolar pressure (PAlv) and in lung volume on the net transvascular fluid filtration rate (FFR). The preparation was isolated, perfused zone III rabbit lungs. In observation periods the outflow pressure was kept constant at a level generally causing net filtration. All pressures were measured relative to atmospheric. FFR was measured by continuous monitoring of preparation weight. Elevation of Palv at constant lung volume caused reversible reductions in FFR, also at constant capillary hydrostatic pressure (Pa-V less than 2 Torr). Increases in lung volume at constant PAlv caused reversible increases in FFR. When both PAlv and Ptp were increased a reduction in FFR was seen in the majority of cases. We conclude that at constant pulmonary arterial pressure, the size and the direction of the influence of positive airway pressure on FFR depend on the relative change in lung volume and in alveolar pressure per se. Under the present experimental conditions a rise in PAlv will be transmitted to interstitial fluid pressure and affect the transvascular fluid balance.

scholarly journals Lung elastic recoil during breathing at increased lung volume

1999 ◽  
Vol 87 (4) ◽  
pp. 1491-1495 ◽  
Author(s):  
Joseph R. Rodarte ◽  
Gassan Noredin ◽  
Charles Miller ◽  
Vito Brusasco ◽  
Riccardo Pellegrino ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Tidal Volume ◽  
Lung Volume ◽  
Normal Subjects ◽  
Dynamic Hyperinflation ◽  
Airway Closure ◽  
Elastic Recoil ◽  
Volume Increase ◽  
Before And After ◽  
Residual Capacity

During dynamic hyperinflation with induced bronchoconstriction, there is a reduction in lung elastic recoil at constant lung volume (R. Pellegrino, O. Wilson, G. Jenouri, and J. R. Rodarte. J. Appl. Physiol. 81: 964–975, 1996). In the present study, lung elastic recoil at control end inspiration was measured in normal subjects in a volume displacement plethysmograph before and after voluntary increases in mean lung volume, which were achieved by one tidal volume increase in functional residual capacity (FRC) with constant tidal volume and by doubling tidal volume with constant FRC. Lung elastic recoil at control end inspiration was significantly decreased by ∼10% within four breaths of increasing FRC. When tidal volume was doubled, the decrease in computed lung recoil at control end inspiration was not significant. Because voluntary increases of lung volume should not produce airway closure, we conclude that stress relaxation was responsible for the decrease in lung recoil.

Effects of altering ventilation on steady-state diffusing capacity for carbon monoxide

1963 ◽  
Vol 18 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Kaye H. Kilburn ◽  
Harry A. Miller ◽  
John E. Burton ◽  
Ronald Rhodes
Keyword(s):  
Carbon Monoxide ◽  
Steady State ◽  
Tidal Volume ◽  
Lung Volume ◽  
Dead Space ◽  
Control Level ◽  
Alveolar Ventilation ◽  
Positive Pressure ◽  
Diffusing Capacity ◽  
Fixed Rate

Alterations in the steady-state diffusing capacity for carbon monoxide (Dco) by the method of Filley, MacIntosh, and Wright, produced by sequential changes in the pattern of breathing were studied in anesthetized, paralyzed, artificially ventilated dogs. The Dco of paralyzed, artificially ventilated control dogs did not differ significantly during 3 hr from values found in conscious and anesthetized controls. A fivefold increase in tidal volume without changing frequency of breathing raised alveolar ventilation and CO uptake 500% and Dco 186%. A high correlation between tidal volume and Dco was noted during reciprocal alterations of tidal volume and rate which maintained minute volume. The Dco appeared to fall when alveolar ventilation was tripled by increments of rate with a fixed-tidal volume, despite a 63% increase in CO uptake. Doubling end-expiratory lung volume by positive pressure breathing without altering tidal volume or rate did not affect Dco. The addition of 100 ml of external dead space with rate and tidal volume constant decreased Dco to 42% of control level, however, stepwise reduction of dead space from 100 ml to 0 in two dogs failed to change Dco. Added dead space equal to frac12 tidal volume (170 ml) reduced Dco to 25% of control in two dogs with a return to control with removal of dead space. Thus, in paralyzed artificially ventilated dogs, tidal volume appears to be the principal ventilatory determinant of steady-state Dco. Dco is minimally affected by increases in alveolar ventilation with a constant tidal volume effected by increasing the frequency of breathing. Prolonged ventilation, at fixed rate and volume, and increased dead space either did not effect, or they reduced Dco, perhaps by rendering less uniform the distribution of gas, and blood in the lungs. Although lung volume was doubled by positive-pressure breathing, pulmonary capillary blood volume was probably reduced to produce opposing effects on diffusing capacity and no net change. Submitted on March 14, 1962

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