Effects of chest wall vibration on tidal volume and functional residual capacity in healthy volunteers.

We assessed the effects of sustained weightlessness on chest wall mechanics in five astronauts who were studied before, during, and after the 10-day Spacelab D-2 mission ( n = 3) and the 180-day Euromir-95 mission ( n= 2). We measured flow and pressure at the mouth and rib cage and abdominal volumes during resting breathing and during a relaxation maneuver from midinspiratory capacity to functional residual capacity. Microgravity produced marked and consistent changes (Δ) in the contribution of the abdomen to tidal volume [ΔVab/(ΔVab + ΔVrc), where Vab is abdominal volume and Vrc is rib cage volume], which increased from 30.7 ± 3.5 (SE)% at 1 G head-to-foot acceleration to 58.3 ± 5.7% at 0 G head-to-foot acceleration ( P < 0.005). Values of ΔVab/(ΔVab + ΔVrc) did not change significantly during the 180 days of the Euromir mission, but in the two subjects ΔVab/(ΔVab + ΔVrc) was greater on postflight day 1 than on subsequent postflight days or preflight. In the two subjects who produced satisfactory relaxation maneuvers, the slope of the Konno-Mead plot decreased in microgravity; this decrease was entirely accounted for by an increase in abdominal compliance because rib cage compliance did not change. These alterations are similar to those previously reported during short periods of weightlessness inside aircrafts flying parabolic trajectories. They are also qualitatively similar to those observed on going from upright to supine posture; however, in contrast to microgravity, such postural change reduces rib cage compliance.

Download Full-text

Dynamic mechanisms determine functional residual capacity in mice, Mus musculus

Journal of Applied Physiology ◽

10.1152/jappl.1979.46.5.867 ◽

1979 ◽

Vol 46 (5) ◽

pp. 867-871 ◽

Cited By ~ 82

Author(s):

A. Vinegar ◽

E. E. Sinnett ◽

D. E. Leith

Keyword(s):

Tidal Volume ◽

Functional Residual Capacity ◽

Flow Volume ◽

Linear Portion ◽

Volume Curve ◽

Flow Volume Curve ◽

Residual Capacity ◽

Expiratory Flow ◽

The Difference ◽

Pentobarbital Sodium Anesthesia

Awake mice (22.6--32.6 g) were anesthetized intravenously during head-out body plethysmography. One minute after pentobarbital sodium anesthesia, tidal volume had fallen from 0.28 +/- 0.04 to 0.14 +/- 0.02 ml and frequency from 181 +/- 20 to 142 +/- 8. Functional residual capacity (FRC) decreased by 0.10 +/- 0.02 ml. Expiratory flow-volume curves were linear, highly repeatable, and submaximal over substantial portions of expiration in awake and anesthetized mice; and expiration was interrupted at substantial flows that abruptly fell to and crossed zero as inspiration interrupted relaxed expiration. FRC is maintained at a higher level in awake mice due to a higher tidal volume and frequency coupled with expiratory braking (persistent inspiratory muscle activity or increased glottal resistance). In anesthetized mice, the absence of braking, coupled with reductions in tidal volume and frequency and a prolonged expiratory period, leads to FRCs that approach relaxation volume (Vr). An equation in derived to express the difference between FRC and Vr in terms of the portion of tidal volume expired without braking, the slope of the linear portion of the expiratory flow-volume curve expressed as V/V, the time fraction of one respiratory cycle spent in unbraked expiration, and respiratory frequency.

Download Full-text

Abdominal distension alters regional pleural pressures and chest wall mechanics in pigs in vivo

Journal of Applied Physiology ◽

10.1152/jappl.1991.70.6.2611 ◽

1991 ◽

Vol 70 (6) ◽

pp. 2611-2618 ◽

Cited By ~ 130

Author(s):

T. Mutoh ◽

W. J. Lamm ◽

L. J. Embree ◽

J. Hildebrandt ◽

R. K. Albert

Keyword(s):

Chest Wall ◽

Respiratory System ◽

Functional Residual Capacity ◽

Total Lung Capacity ◽

Abdominal Cavity ◽

Abdominal Distension ◽

Abdominal Pressure ◽

Lung Capacity ◽

Lung Expansion ◽

Residual Capacity

Abdominal distension (AD) occurs in pregnancy and is also commonly seen in patients with ascites from various causes. Because the abdomen forms part of the "chest wall," the purpose of this study was to clarify the effects of AD on ventilatory mechanics. Airway pressure, four (vertical) regional pleural pressures, and abdominal pressure were measured in five anesthetized, paralyzed, and ventilated upright pigs. The effects of AD on the lung and chest wall were studied by inflating a liquid-filled balloon placed in the abdominal cavity. Respiratory system, chest wall, and lung pressure-volume (PV) relationships were measured on deflation from total lung capacity to residual volume, as well as in the tidal breathing range, before and 15 min after abdominal pressure was raised. Increasing abdominal pressure from 3 to 15 cmH2O decreased total lung capacity and functional residual capacity by approximately 40% and shifted the respiratory system and chest wall PV curves downward and to the right. Much smaller downward shifts in lung deflation curves were seen, with no change in the transdiaphragmatic PV relationship. All regional pleural pressures increased (became less negative) and, in the dependent region, approached 0 cmH2O at functional residual capacity. Tidal compliances of the respiratory system, chest wall, and lung were decreased 43, 42, and 48%, respectively. AD markedly alters respiratory system mechanics primarily by "stiffening" the diaphragm/abdomen part of the chest wall and secondarily by restricting lung expansion, thus shifting the lung PV curve as seen after chest strapping. The less negative pleural pressures in the dependent lung regions suggest that nonuniformities of ventilation could also be accentuated and gas exchange impaired by AD.

Download Full-text

Estimation of pulmonary ventilation with nitrogen and helium, using the mass spectrometer

Journal of Applied Physiology ◽

10.1152/jappl.1959.14.4.499 ◽

1959 ◽

Vol 14 (4) ◽

pp. 499-506 ◽

Cited By ~ 1

Author(s):

K. Tokuyasu ◽

A. Coblentz ◽

H. R. Bierman

Keyword(s):

Tidal Volume ◽

Mass Spectrometer ◽

Functional Residual Capacity ◽

Pulmonary Ventilation ◽

Normal Subjects ◽

Alveolar Ventilation ◽

Pulmonary Lesions ◽

Normal Subject ◽

Residual Capacity ◽

Uneven Ventilation

Estimation of pulmonary ventilation was attempted by measuring the elimination of nitrogen and helium with the mass spectrometer. Exhalatory concentrations of nitrogen and helium were continuously recorded in each of 12 normal subjects and 10 patients with pulmonary enphysema or space-occupying pulmonary lesions. Uniform values for both slow and rapid uneven ventilation were found in all normal subjects but always less than in emphysematous states. Ratios of effective tidal volume (Vt) and alveolar ventilation volume (f·Vt) to functional residual capacity P = Vt/Vr and Q = f·Vt/Vr were one half or less than those in the normal subject. Smaller values of uneven ventilation were found for helium than nitrogen. Data computed by the theory of 'periodic' ventilation gave greater values for uneven ventilation (Q) and more accurately represented the physiologic conditions than derived by ‘continuous’ ventilation. Submitted on August 7, 1958

Download Full-text

Measuring tidal volume and functional residual capacity change in sleeping infants using a volume displacement plethysmograph

CrossRef Listing of Deleted DOIs ◽

10.1183/09031936.98.12051186 ◽

1998 ◽

Vol 12 (5) ◽

pp. 1186-1190 ◽

Cited By ~ 6

Author(s):

S.J. Wilson ◽

C. O'Brien ◽

M.A. Harris ◽

I.B. Masters

Keyword(s):

Tidal Volume ◽

Functional Residual Capacity ◽

Capacity Change ◽

Residual Capacity

Download Full-text

Ventilatory compensation for changes in functional residual capacity during sleep

Journal of Applied Physiology ◽

10.1152/jappl.1987.62.3.1299 ◽

1987 ◽

Vol 62 (3) ◽

pp. 1299-1306 ◽

Cited By ~ 13

Author(s):

R. L. Begle ◽

J. B. Skatrud ◽

J. A. Dempsey

Keyword(s):

Tidal Volume ◽

Functional Residual Capacity ◽

Minute Ventilation ◽

Muscle Length ◽

Normal Subjects ◽

Conscious State ◽

Inspiratory Muscle ◽

Compensatory Response ◽

Inspiratory Muscles ◽

Residual Capacity

The role of conscious factors in the ventilatory compensation for shortened inspiratory muscle length and the potency of this compensatory response were studied in five normal subjects during non-rapid-eye-movement sleep. To shorten inspiratory muscles, functional residual capacity (FRC) was increased and maintained for 2–3 min at a constant level (range of increase 160–1,880 ml) by creating negative pressure within a tank respirator in which the subjects slept. Minute ventilation was maintained in all subjects over the entire range of increased FRC (mean change +/- SE = -3 +/- 1%) through preservation of tidal volume (-2 +/- 2%) despite slightly decreased breathing frequency (-6 +/- 2%). The decrease in frequency (-13 +/- 2%) was due to a prolongation in expiratory time. Inspiratory time shortened (-10 +/- 1%). Mean inspiratory flow increased 15 +/- 3% coincident with an increase in the slope of the moving time average of the integrated surface diaphragmatic electromyogram (67 +/- 21%). End-tidal CO2 did not rise. In two subjects, control tidal volume was increased 35–50% with CO2 breathing. This augmented tidal volume was still preserved when FRC was increased. We concluded that the compensatory response to inspiratory muscle shortening did not require factors associated with the conscious state. In addition, the potency of this response was demonstrated by preservation of tidal volume despite extreme shortening of the inspiratory muscles and increase in control tidal volumes caused by CO2 breathing. Finally, the timing changes we observed may be due to reflexes following shortening of inspiratory muscle length, increase in abdominal muscle length, or cardiovascular changes.

Download Full-text

Crural diaphragm activation during dynamic contractions at various inspiratory flow rates

Journal of Applied Physiology ◽

10.1152/jappl.1998.85.2.451 ◽

1998 ◽

Vol 85 (2) ◽

pp. 451-458 ◽

Cited By ~ 36

Author(s):

Jennifer Beck ◽

Christer Sinderby ◽

Lars Lindström ◽

Alex Grassino

Keyword(s):

Chest Wall ◽

Functional Residual Capacity ◽

Healthy Subjects ◽

Total Lung Capacity ◽

Inspiratory Flow ◽

Transdiaphragmatic Pressure ◽

Flow Rates ◽

Lung Capacity ◽

Dynamic Contractions ◽

Residual Capacity

The purpose of this study was to evaluate the influence of velocity of shortening on the relationship between diaphragm activation and pressure generation in humans. This was achieved by relating the root mean square (RMS) of the diaphragm electromyogram to the transdiaphragmatic pressure (Pdi) generated during dynamic contractions at different inspiratory flow rates. Five healthy subjects inspired from functional residual capacity to total lung capacity at different flow rates while reproducing identical Pdi and chest wall configuration profiles. To change the inspiratory flow rate, subjects performed the inspirations while breathing across two different inspiratory resistances (10 and 100 cmH2O ⋅ l−1 ⋅ s), at mouth pressure targets of −10, −20, −40, and −60 cmH2O. The diaphragm electromyogram was recorded and analyzed with control of signal contamination and electrode positioning. RMS values obtained for inspirations with identical Pdi and chest wall configuration profiles were compared at the same percentage of inspiratory duration. At inspiratory flows ranging between 0.1 and 1.4 l/s, there was no difference in the RMS for the inspirations from functional residual capacity to total lung capacity when Pdi and chest wall configuration profiles were reproduced ( n = 4). At higher inspiratory flow rates, subjects were not able to reproduce their chest wall displacements and adopted different recruitment patterns. In conclusion, there was no evidence for increased demand of diaphragm activation when healthy subjects breathe with similar chest wall configuration and Pdi profiles, at increasing flow rates up to 1.4 l/s.

Download Full-text

Effects of mean airway pressure and tidal volume on lung and chest wall mechanics in the dog

Journal of Applied Physiology ◽

10.1152/jappl.1993.74.5.2286 ◽

1993 ◽

Vol 74 (5) ◽

pp. 2286-2293 ◽

Cited By ~ 29

Author(s):

G. M. Barnas ◽

J. Sprung

Keyword(s):

Mechanical Properties ◽

Tidal Volume ◽

Chest Wall ◽

Respiratory System ◽

Lung Volume ◽

Airway Pressure ◽

Dynamic Mechanical Properties ◽

Mean Airway Pressure ◽

Residual Capacity ◽

Normal Mean

Dependencies of the dynamic mechanical properties of the respiratory system on mean airway pressure (Paw) and the effects of tidal volume (VT) are not completely clear. We measured resistance and dynamic elastance of the total respiratory system (Rrs and Ers), lungs (RL and EL), and chest wall (Rcw and Ecw) in six healthy anesthetized paralyzed dogs during sinusoidal volume oscillations at the trachea (50–300 ml; 0.4 Hz) delivered at mean Paw from -9 to +23 cmH2O. Changes in end-expiratory lung volume, estimated with inductance plethysmographic belts, showed a typical sigmoidal relationship to mean Paw. Each dog showed the same dependencies of mechanical properties on mean Paw and VT. All elastances and resistances were minimal between 5 and 10 cmH2O mean Paw. All elastances, Rrs, and RL increased greatly with decreasing Paw below 5 cmH2O. Ers and EL increased above 10 cmH2O. Ecw, Ers, Rcw, and Rrs decreased slightly with increasing VT, but RL and EL were independent of VT. We conclude that 1) respiratory system impedance is minimal at the normal mean lung volume of supine anesthetized paralyzed dogs; 2) the dependency of RL on lung volume above functional residual capacity is dependent on VT and respiratory frequency; and 3) chest wall, but not lung, mechanical behavior is nonlinear (i.e., VT dependent) at any given lung volume.

Download Full-text

Pulmonary compliance and nonelastic resistance during treadmill exercise

Journal of Applied Physiology ◽

10.1152/jappl.1965.20.6.1194 ◽

1965 ◽

Vol 20 (6) ◽

pp. 1194-1198 ◽

Cited By ~ 8

Author(s):

S. T. Chiang ◽

Neal H. Steigbigel ◽

Harold A. Lyons

Keyword(s):

Tidal Volume ◽

Functional Residual Capacity ◽

Treadmill Exercise ◽

Normal Subjects ◽

Lung Compliance ◽

Respiratory Frequency ◽

Respiratory Flow ◽

Pulmonary Compliance ◽

Exercise Effect ◽

Residual Capacity

Trans-pulmonary pressure, respiratory flow, and tidal volume of seven normal subjects were measured at rest and during treadmill exercise on the level at a speed of 1.5 mph. Pulmonary compliance remained unchanged during exercise. Nonelastic resistance showed an insignificant increase (0.9—1.4 cm H2O per liter per sec). Examination of other parameters which may affect compliance were made. Functional residual capacity decreased 120—200 ml during exercise, tidal volume doubled, and respiratory frequency increased 43.5%, yet none of these factors affected the lung compliance. The phenomenon of “second wind” was experienced by four of the subjects, and nothing was observed to explain its occurrence during exercise. exercise second wind; change in functional residual capacity during exercise; effect of functional residual capacity on compliance; effect of tidal volume on compliance during exercise; effect of respiratory frequency on compliance Submitted on January 15, 1965

Download Full-text