scholarly journals Inspiratory Capacity as an Indirect Measure of Immediate Effects of Positive Expiratory Pressure and CPAP Breathing on Functional Residual Capacity in Healthy Subjects

2015 ◽  
Vol 60 (10) ◽  
pp. 1486-1494 ◽  
Author(s):  
M. Sehlin ◽  
O. Winso ◽  
K. Wadell ◽  
F. Ohberg
Keyword(s):  
Functional Residual Capacity ◽  
Healthy Subjects ◽  
Inspiratory Capacity ◽  
Indirect Measure ◽  
Residual Capacity ◽  
Positive Expiratory Pressure

Crural diaphragm activation during dynamic contractions at various inspiratory flow rates

1998 ◽  
Vol 85 (2) ◽  
pp. 451-458 ◽  
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.

Airway closure during anesthesia: a comparison between resident-gas and argon-bolus techniques

1979 ◽  
Vol 47 (4) ◽  
pp. 874-881 ◽  
Author(s):  
G. Hedenstierna ◽  
J. Santesson
Keyword(s):  
Functional Residual Capacity ◽  
Lung Volume ◽  
Healthy Subjects ◽  
Abrupt Onset ◽  
Closing Volume ◽  
Residual Volume ◽  
Airway Closure ◽  
Venous Admixture ◽  
Residual Capacity ◽  
Nitrogen Concentrations

Airway closure was measured in awake and then anesthetized supine healthy subjects with the argon-bolus and the resident-gas (nitrogen) techniques simultaneously. The preinspiratory lung volume for the closing volume maneuver was varied from residual volume to closing capacity (CC). Comparative measurements were also performed in the upright and supine positions in awake subjects. Closing volume (CV) was consistently larger with the bolus technique in supine subjects both when awake and when anesthetized (difference between methods 0.1--0.2 l, P less than 0.01), whereas no difference between the methods was noted in upright subjects. The lower “nitrogen CV” in supine subjects may be due to a shorter vertical lung height with a smaller range of nitrogen concentrations, resulting in a less abrupt onset of phase IV (taken to indicate CV). CV was not significantly affected by the preinspiratory lung volume with either technique, and CC was unchanged when anesthesia was instituted. Functional residual capacity (FRC) was reduced with anesthesia (mean reduction: 0.6 l, P less than 0.01) and FRC-CC became negative in all subjects with either technique. This implies intermittent or continuous airway closure during anesthesia and the possibility of increased venous admixture.

Assessment of maximal expiratory pressure in healthy adults

1988 ◽  
Vol 64 (5) ◽  
pp. 2215-2219 ◽  
Author(s):  
I. Rubinstein ◽  
A. S. Slutsky ◽  
A. S. Rebuck ◽  
P. A. McClean ◽  
R. Boucher ◽  
...  
Keyword(s):  
Functional Residual Capacity ◽  
Muscle Function ◽  
Healthy Subjects ◽  
Normal Values ◽  
Scuba Diving ◽  
The Other ◽  
Expiratory Muscle ◽  
Hands On ◽  
Wide Variability ◽  
Residual Capacity

Maximal static expiratory pressure developed at the mouth (PEmax) provides a useful clinical index of expiratory muscle function; however, the range of normal values among laboratories shows considerable variation. We examined the hypothesis that the wide variability could be attributable to the differences in technique among laboratories. We measured PEmax at functional residual capacity (PEmax FRC) in 28 healthy subjects using the following five techniques: 1) using a scuba-type mouthpiece with the cheeks supported by the hands ("hands on"), 2) without supporting the cheeks ("no hands"), 3) using a rigid, circular mouthpiece (2.8 cm ID, "tube"), 4) using the scuba-type mouthpiece but with the cheeks supported by an observer ("other hands"), and 5) using a large-bore circular mouthpiece (4.1 cm ID, "new tube"). Mean PEmax FRC obtained with hands on was significantly higher than no-hands and tube methods. PEmax FRC values obtained by the other-hands and new-tube maneuvers were similar to the hands-on maneuver. We conclude that the technique used to measure PEmax FRC can significantly affect the results and suggest that it should be measured using a large-bore circular mouthpiece or a scuba-diving mouthpiece with the cheeks supported.

scholarly journals Comparison of inspiratory and expiratory lung and lobe volumes among supine, standing, and sitting positions using conventional and upright CT

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yoshitake Yamada ◽  
Minoru Yamada ◽  
Shotaro Chubachi ◽  
Yoichi Yokoyama ◽  
Shiho Matsuoka ◽  
...  
Keyword(s):  
Pulmonary Function ◽  
Functional Residual Capacity ◽  
Supine Position ◽  
Total Lung Capacity ◽  
Middle Lobe ◽  
Inspiratory Capacity ◽  
Lung Volumes ◽  
Lung Capacity ◽  
Residual Capacity ◽  
Right Middle Lobe

Abstract Currently, no clinical studies have compared the inspiratory and expiratory volumes of unilateral lung or of each lobe among supine, standing, and sitting positions. In this prospective study, 100 asymptomatic volunteers underwent both low-radiation-dose conventional (supine position, with arms raised) and upright computed tomography (CT) (standing and sitting positions, with arms down) during inspiration and expiration breath-holds and pulmonary function test (PFT) on the same day. We compared the inspiratory/expiratory lung/lobe volumes on CT in the three positions. The inspiratory and expiratory bilateral upper and lower lobe and lung volumes were significantly higher in the standing/sitting positions than in the supine position (5.3–14.7% increases, all P < 0.001). However, the inspiratory right middle lobe volume remained similar in the three positions (all P > 0.15); the expiratory right middle lobe volume was significantly lower in the standing/sitting positions (16.3/14.1% decrease) than in the supine position (both P < 0.0001). The Pearson’s correlation coefficients (r) used to compare the total lung volumes on inspiratory CT in the supine/standing/sitting positions and the total lung capacity on PFT were 0.83/0.93/0.95, respectively. The r values comparing the total lung volumes on expiratory CT in the supine/standing/sitting positions and the functional residual capacity on PFT were 0.83/0.85/0.82, respectively. The r values comparing the total lung volume changes from expiration to inspiration on CT in the supine/standing/sitting positions and the inspiratory capacity on PFT were 0.53/0.62/0.65, respectively. The study results could impact preoperative CT volumetry of the lung in lung cancer patients (before lobectomy) for the prediction of postoperative residual pulmonary function, and could be used as the basis for elucidating undetermined pathological mechanisms. Furthermore, in addition to morphological evaluation of the chest, inspiratory and expiratory upright CT may be used as an alternative tool to predict lung volumes such as total lung capacity, functional residual capacity, and inspiratory capacity in situation in which PFT cannot be performed such as during an infectious disease pandemic, with relatively more accurate predictability compared with conventional supine CT.

Estimation of inspiratory capacity in health and in subjects with respiratory muscle paralysis

1959 ◽  
Vol 14 (3) ◽  
pp. 279-283 ◽  
Author(s):  
William A. Spencer ◽  
Carlos Vallbona
Keyword(s):  
Healthy Subjects ◽  
Respiratory Muscle ◽  
Muscle Paralysis ◽  
Volume Changes ◽  
Inspiratory Capacity ◽  
Lung Capacity ◽  
System A ◽  
Residual Capacity ◽  
Low Pressures

A method is described for the reproduction of the natural inspiratory capacity in healthy subjects utilizing a pressure breathing device capable of delivering high inflow rates at low pressures (1.3 l/sec. at 5 cm of water in the delivery system). A highly significant correlation was found between natural inspiratory capacity and the estimation of inspiratory capacity carried out in this manner in healthy subjects. The reliability of this method in cooperative individuals suggested applicability in patients with respiratory muscle paralysis when maximum natural inspiration is impossible. In poliomyelitis subjects with respiratory muscle paralysis the values of estimated inspiratory capacity were significantly reduced below those found in health. The degree of reduction was not directly related to the diminution of natural inspiratory capacity or to the maximum volume changes that could be produced by means of tank respirator assistance at comparable peak transthoracic pressures. Measurement of inspiratory capacity with this technique together with the determination of functional residual capacity makes it practical to estimate the total lung capacity and thus describe the lung compartments in such subjects. Submitted on June 10, 1958

Dispersion of 0.5- to 2-μm aerosol in μG and hypergravity as a probe of convective inhomogeneity in the lung

1999 ◽  
Vol 86 (4) ◽  
pp. 1402-1409 ◽  
Author(s):  
Chantal Darquenne ◽  
John B. West ◽  
G. Kim Prisk
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Functional Residual Capacity ◽  
Healthy Subjects ◽  
Distal Part ◽  
Sedimentation Velocity ◽  
Residual Volume ◽  
Gas Mixing ◽  
Residual Capacity ◽  
Expired Gas

We used aerosol boluses to study convective gas mixing in the lung of four healthy subjects on the ground (1 G) and during short periods of microgravity (μG) and hypergravity (∼1.6 G). Boluses of 0.5-, 1-, and 2-μm-diameter particles were inhaled at different points in an inspiration from residual volume to 1 liter above functional residual capacity. The volume of air inhaled after the bolus [the penetration volume (Vp)] ranged from 150 to 1,500 ml. Aerosol concentration and flow rate were continuously measured at the mouth. The dispersion, deposition, and position of the bolus in the expired gas were calculated from these data. For each particle size, both bolus dispersion and deposition increased with Vp and were gravity dependent, with the largest dispersion and deposition occurring for the largest G level. Whereas intrinsic particle motions (diffusion, sedimentation, inertia) did not influence dispersion at shallow depths, we found that sedimentation significantly affected dispersion in the distal part of the lung (Vp >500 ml). For 0.5-μm-diameter particles for which sedimentation velocity is low, the differences between dispersion in μG and 1 G likely reflect the differences in gravitational convective inhomogeneity of ventilation between μG and 1 G.

scholarly journals Quantitative assessment of multiscale structural and functional alterations in asthmatic populations

2015 ◽  
Vol 118 (10) ◽  
pp. 1286-1298 ◽  
Author(s):  
Sanghun Choi ◽  
Eric A. Hoffman ◽  
Sally E. Wenzel ◽  
Mario Castro ◽  
Sean B. Fain ◽  
...  
Keyword(s):  
Pulmonary Function ◽  
Functional Residual Capacity ◽  
Volume Change ◽  
Healthy Subjects ◽  
Air Trapping ◽  
Bifurcation Angle ◽  
Computed Tomography Images ◽  
Severe Asthmatic ◽  
Structural Variables ◽  
Residual Capacity

Relationships between structural and functional variables in asthmatic lungs at local and global (or lobar) levels remain to be discovered. This study aims to investigate local alterations of structural variables [bifurcation angle, circularity, airway wall thickness (WT), and hydraulic diameter ( Dh)] in asthmatic subjects, and their correlations with other imaging and pulmonary function test-based global and lobar metrics, including lung shape, air-trapping, regional volume change, and more. Sixty-one healthy subjects, and 67 nonsevere and 67 severe asthmatic subjects were studied. The structural variables were derived from computed tomography images at total lung capacity (TLC). Air-trapping was measured at functional residual capacity, and regional volume change (derived from image registration) was measured between functional residual capacity and TLC. The tracheal diameter and WT predicted by 61 healthy subjects were used to normalize the Dh and WT. New normalization schemes allowed for the dissociation of luminal narrowing and wall thickening effects. In severe asthmatic subjects, the alteration of bifurcation angle was found to be correlated with a global lung shape at TLC, and circularity was significantly decreased in the right main bronchus. While normalized WT increased especially in the upper lobes of severe asthmatic subjects, normalized Dh decreased in the lower lobes. Among local structural variables, normalized Dh was the most representative variable, because it was significantly correlated with alterations of functional variables, including pulmonary function test's data. In conclusion, understanding multiscale phenomena may help to provide guidance in the search for potential imaging-based phenotypes for the development and outcomes assessment of therapeutic intervention.

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