Inspiratory muscles during exercise: a problem of supply and demand

1988 ◽  
Vol 64 (6) ◽  
pp. 2482-2489 ◽  
Author(s):  
P. Leblanc ◽  
E. Summers ◽  
M. D. Inman ◽  
N. L. Jones ◽  
E. J. Campbell ◽  
...  
Keyword(s):  
Lung Volume ◽  
Static Pressure ◽  
Total Lung Capacity ◽  
Supply And Demand ◽  
Normal Subjects ◽  
Esophageal Pressure ◽  
Maximum Exercise ◽  
Lung Capacity ◽  
Inspiratory Muscles ◽  
Residual Capacity

The capacity of inspiratory muscles to generate esophageal pressure at several lung volumes from functional residual capacity (FRC) to total lung capacity (TLC) and several flow rates from zero to maximal flow was measured in five normal subjects. Static capacity was 126 +/- 14.6 cmH2O at FRC, remained unchanged between 30 and 55% TLC, and decreased to 40 +/- 6.8 cmH2O at TLC. Dynamic capacity declined by a further 5.0 +/- 0.35% from the static pressure at any given lung volume for every liter per second increase in inspiratory flow. The subjects underwent progressive incremental exercise to maximum power and achieved 1,800 +/- 45 kpm/min and maximum O2 uptake of 3,518 +/- 222 ml/min. During exercise peak esophageal pressure increased from 9.4 +/- 1.81 to 38.2 +/- 5.70 cmH2O and end-inspiratory esophageal pressure increased from 7.8 +/- 0.52 to 22.5 +/- 2.03 cmH2O from rest to maximum exercise. Because the estimated capacity available to meet these demands is critically dependent on end-inspiratory lung volume, the changes in lung volume during exercise were measured in three of the subjects using He dilution. End-expiratory volume was 52.3 +/- 2.42% TLC at rest and 38.5 +/- 0.79% TLC at maximum exercise.

Elastic properties of the lung in acute induced asthma

1983 ◽  
Vol 54 (1) ◽  
pp. 152-158 ◽  
Author(s):  
D. Rodenstein ◽  
D. C. Stanescu
Keyword(s):  
Lung Volume ◽  
Static Pressure ◽  
Total Lung Capacity ◽  
Esophageal Pressure ◽  
Elastic Recoil ◽  
Rapid Loss ◽  
Asthmatic Patients ◽  
Clear Cut ◽  
Lung Capacity ◽  
Significant Change

In acute induced asthma, plethysmographic total lung capacity (TLCm) was reported to increase and lung elastic recoil [Pst(L)] to decrease. The increase in TLC is spurious (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 52: 939–954, 1982), so that the rapid loss in Pst(L) could be due to errors in lung volume. We studied seven asthmatic patients before and during an induced bronchospasm. TLC was derived simultaneously from mouth and esophageal pressure vs. plethysmographic volume plots (TLCm and TLCes, respectively). Before bronchospasm, TLCm and TLCes were similar. During bronchospasm average TLCm increased, from 7.30 +/- 1.34 (SD) to 8.12 +/- 1.49 liters (P less than 0.001), whereas TLCes did not (P greater than 0.60). Static pressure-volume curves, derived from TLCes (P-Ves), were superimposed on prechallenge curves or only slightly shifted to the left, whereas those derived from TLCm (P-Vm) showed a clear-cut parallel shift to the left. At 70% of control TLC there was no significant change in Pst(L) measured from P-Ves curves (7.3 +/- 3.1 cmH2O before bronchospasm; 6.7 +/- 2.3 cmH2O during bronchospasm, P greater than 0.10), whereas Pst(L) measured from P-Vm curves decreased from 7.3 +/- 3.1 to 5.1 +/- 2.4 cmH2O (P less than 0.01). No significant change in Pst(L) at TLC was observed during bronchospasm. We conclude that in our patients acute decrease in Pst(L) during induced asthma was artifactual, secondary to lung volume overestimation by body plethysmography.

Maximal shortening of inspiratory muscles: effect of training

1983 ◽  
Vol 54 (6) ◽  
pp. 1618-1623 ◽  
Author(s):  
C. H. Fanta ◽  
D. E. Leith ◽  
R. Brown
Keyword(s):  
Lung Volume ◽  
Vital Capacity ◽  
Total Lung Capacity ◽  
Training Group ◽  
Normal Subjects ◽  
Pressure Control ◽  
Base Line ◽  
Lung Capacity ◽  
Inspiratory Muscles ◽  
The Mean

Normal subjects can increase their vital capacity by appropriate training. We tested whether that change can be achieved by greater maximal shortening of the inspiratory muscles without concomitant increases in peak static inspiratory pressures. Sixteen healthy volunteers participated in the study: eight were randomly assigned to make 20 inhalations to total lung capacity, held for 10 s with the glottis open, each day for 6 wk; the remainder served as nontraining controls. Before and after the 6-wk study period, we made multiple determinations of lung volumes and of curves relating lung volume to maximal static inspiratory (and expiratory) pressure. Control subjects had no significant changes from base line in any variable. In the training group, the mean vital capacity increased 200 +/- 74 ml (P less than 0.05) or 3.9 +/- 1.3% (P less than 0.02), without a significant change in residual volume. After training, the mean maximal inspiratory pressure at the airway opening (PI) at a lung volume equal to the base-line total lung capacity was 27 +/- 8 cmH2O in this group (vs. zero before training; P less than 0.02). Values of PI in the mid-vital capacity range did not change. We conclude that in response to appropriate training stimuli inspiratory muscles can contract to shorter minimal lengths, a capacity potentially important in progressive pulmonary hyperinflation.

Lung volume and effectiveness of inspiratory muscles

1993 ◽  
Vol 74 (2) ◽  
pp. 688-694 ◽  
Author(s):  
A. Brancatisano ◽  
L. A. Engel ◽  
S. H. Loring
Keyword(s):  
Lung Volume ◽  
Muscle Activity ◽  
Vital Capacity ◽  
Total Lung Capacity ◽  
Normal Subjects ◽  
Lung Volumes ◽  
Mechanical Advantage ◽  
Lung Capacity ◽  
Inspiratory Muscles ◽  
Volume Dependence

We related inspiratory muscle activity to inspiratory pressure generation (Pmus) at different lung volumes in five seated normal subjects. Integrated electromyograms were recorded from diaphragmatic crura (Edi), parasternals (PS), and lateral external intercostals (EI). At 20% increments in the vital capacity (VC) subjects relaxed and then made graded and maximal inspiratory efforts against an occluded airway. At any given level of pressure generation, Edi, PS, and EI increased with increasing lung volume. The Pmus generated at total lung capacity as a fraction of that at a low lung volume (between residual volume and 40% VC) was 0.39 +/- 0.15 (SD) for the diaphragm, 0.20 +/- 0.06 for PS, and 0.22 +/- 0.04 for the lateral EI muscles. Our results indicate a lesser volume dependence of the Pmus-EMG relationship for the diaphragm than for PS and EI muscles. This difference in muscle effectiveness with lung volume may reflect differences in length-tension and/or geometric mechanical advantage between the rib cage muscles and the diaphragm.

Changes in lung volume and rib cage configuration with abdominal binding in quadriplegia

1986 ◽  
Vol 60 (4) ◽  
pp. 1198-1202 ◽  
Author(s):  
F. D. McCool ◽  
B. M. Pichurko ◽  
A. S. Slutsky ◽  
M. Sarkarati ◽  
A. Rossier ◽  
...  
Keyword(s):  
Total Lung Capacity ◽  
Normal Subjects ◽  
Tidal Range ◽  
Dilution Technique ◽  
Inspiratory Capacity ◽  
Rib Cage ◽  
Lung Capacity ◽  
Residual Capacity ◽  
Helium Dilution ◽  
Combined Data

Previous studies suggest that abdominal binding may affect the interaction of the rib cage and the diaphragm over the tidal range of breathing in quadriplegia. To determine whether abdominal binding influences rib cage motion over the entire range of inspiratory capacity, we used spirometry and the helium-dilution technique to measure functional residual capacity (FRC), inspiratory capacity, and total lung capacity (TLC) in eight quadriplegic and five normal subjects in supine, tilted (37 degrees), and seated positions. Combined data in all three positions indicated that, with abdominal binding, FRC and TLC decreased in normal subjects [delta FRC = -0.33 + 0.151 (SD) P less than 0.01); delta TLC = -0.16 + 0.121, P less than 0.05]. In quadriplegia there was also a reduction in FRC with binding (delta FRC = -0.32 + 0.101, P less than 0.001). However, TLC increased in quadriplegia (delta TLC = 0.07 + 0.061, P less than 0.025). In an additional six quadriplegic and five normal subjects, we used magnetometers to define the influences of abdominal binding on rib cage dimensions and TLC. In quadriplegia, rib cage dimensions were increased at TLC with abdominal binding, whereas there was no change in normals. Our data suggest that this inspiratory effect of abdominal binding on augmenting rib cage volume in quadriplegia is greater than the effect of impeding diaphragm descent, and thus abdominal binding produces a net increase in TLC in quadriplegia.

Effect of body posture on lung volumes

1961 ◽  
Vol 16 (1) ◽  
pp. 27-29 ◽  
Author(s):  
Francisco Moreno ◽  
Harold A. Lyons
Keyword(s):  
Tidal Volume ◽  
Prone Position ◽  
Supine Position ◽  
Total Lung Capacity ◽  
Minute Ventilation ◽  
Normal Subjects ◽  
Body Posture ◽  
Mean Values ◽  
Lung Capacity ◽  
Residual Capacity

The changes produced by body posture on total lung capacity and its subdivisions have been reported for all positions except the prone position. Twenty normal subjects, twelve males and eight females, had determinations of total lung capacity in the three body positions, sitting, supine and prone. Tidal volume, minute ventilation and O2 consumption were also measured. The changes found on assumption of the supine position from the sitting position were similar to those previously reported. For the prone position, a smaller inspiratory capacity and a larger expiratory reserve volume were found. The mean values were changed, respectively, –8% and +37%. Associated with these changes was a significant increase of the functional residual capacity by 636 ml. Ventilation did not change significantly from that found during sitting, unlike the findings associated with the supine position, in which position the tidal volume was decreased. Respiratory frequency remained the same for all positions. Submitted on April 5, 1960

Lung volume dependence of esophageal pressure in the neck

1985 ◽  
Vol 59 (6) ◽  
pp. 1849-1854 ◽  
Author(s):  
I. G. Brown ◽  
P. A. McClean ◽  
P. M. Webster ◽  
V. Hoffstein ◽  
N. Zamel
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Balloon Catheter ◽  
Esophageal Pressure ◽  
Lower Esophagus ◽  
Tissue Pressure ◽  
Lung Capacity ◽  
Volume Dependence ◽  
Conflicting Evidence ◽  
Cervical Trachea

There is conflicting evidence in the literature regarding tissue pressure in the neck. We studied esophageal pressure along cervical and intrathoracic esophageal segments in six healthy men to determine extramural pressure for the cervical and intrathoracic airways. A balloon catheter system with a 1.5-cm-long balloon was used to measure intraesophageal pressures. It was positioned at 2-cm intervals, starting 10 cm above the cardiac sphincter and ending at the cricopharyngeal sphincter. We found that esophageal pressures became more negative as the balloon catheter moved from intrathoracic to cervical segments, until the level of the cricopharyngeal sphincter was reached. At total lung capacity, esophageal pressures were -10.5 +/- 2.9 (SE) cmH2O in the lower esophagus, -18.9 +/- 3.0 just within the thorax, and -21.3 +/- 2.73 within 2 cm of the cricopharyngeal sphincter. The variation in mouth minus esophageal pressure with lung volume was similar in cervical and thoracic segments. We conclude that the subatmospheric tissue pressure applied to the posterior membrane of the cervical trachea results in part from transmission of apical pleural pressure into the neck. Transmural pressure for cervical and thoracic tracheal segments is therefore similar.

Effects of lung volume on collateral and airways resistance in man

1979 ◽  
Vol 46 (1) ◽  
pp. 67-73 ◽  
Author(s):  
C. R. Inners ◽  
P. B. Terry ◽  
R. J. Traystman ◽  
H. A. Menkes
Keyword(s):  
Functional Residual Capacity ◽  
Lung Volume ◽  
Total Lung Capacity ◽  
Lung Capacity ◽  
Residual Capacity ◽  
Collateral Pathways ◽  
Flow Through ◽  
Airways Resistance ◽  
Young Subjects ◽  
The Relationship

The effects of changing lung volume (VL) on collateral resistance (Rcoll) and total airways resistance (Raw) were compared in six young volunteers. At functional residual capacity (FRC) = 55% total lung capacity (TLC), mean Rcoll was 4,664 +/- 1,518 (SE) cmH2O/(l/s) and mean Raw was 1.57 +/- 0.11 (SE) cmH2O/l/s). When VL increased to 80% TLC, Rcoll decreased by 63.3 +/- 7.8%, and Raw decreased by 50.3 +/- 4.2 (SE) %. The decrease in Rcoll with increasing lung volume was not statistically different from that of Raw (P less than 0.05). If the airways obstructed for measurements of Rcoll served between 2 and 5% of the lungs, then Rcoll was approximately 50 times as great as the resistance to flow through airways serving the same volume of lung at FRC. The relationship did not change significantly when VL increased by 25% TLC. If changes in Raw reflect changes in airways supplying sublobar portions of lung, these results indicate that there is no tendency for the redistribution of ventilation through airways and collateral pathways with changes in VL in young subjects.

Lung volume and pleural pressure in the anesthetized hamster

1979 ◽  
Vol 46 (5) ◽  
pp. 927-931 ◽  
Author(s):  
Y. L. Lai
Keyword(s):  
Lung Volume ◽  
Esophageal Pressure ◽  
Lung Compliance ◽  
Pleural Pressure ◽  
Lung Volumes ◽  
Lung Capacity ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Residual Capacity ◽  
Wall Compliance

Lung volumes and respiratory pressures were measured in anesthetized male hamsters weighing an average 117 g. In 16 supine animals functional residual capacity (FRC) determined by body plethysmograph was 1.12 +/- 0.23 (SD) ml (about 20% total lung capacity, TLC) slightly and significantly larger than the FRC measured by saline displacement, 1.01 +/- 0.15 ml. Similar results were found in six prone animals. Paralysis did not significantly alter supine FRC. Contrary to published reports, pleural pressure (Ppl) estimated from esophageal pressure was negative at FRC. The fact that lung volume decreased by 0.2 ml (about 4% TLC) when the chest was opened at FRC provided additional evidence of negative Ppl at FRC. No consistent changes in the lung pressure-volume curve were found after the chest was opened. Deflation chest wall compliance just above FRC was about twice lung compliance. The vital capacity and reserve volumes in this study agreed with values reported in the literature. However, absolute lung volumes (TLC, FRC, and residual volume) were lower by about 1.4 ml, possibly because of earlier overestimates of box FRC.

Airway distensibility in healthy and asthmatic subjects: effect of lung volume history

2000 ◽  
Vol 88 (4) ◽  
pp. 1413-1420 ◽  
Author(s):  
David Peter Johns ◽  
John Wilson ◽  
Richard Harding ◽  
E. Haydn Walters
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Normal Subjects ◽  
Residual Volume ◽  
Tidal Breathing ◽  
Lung Capacity ◽  
Mild Asthmatic ◽  
The Relationship ◽  
Asthmatic Group ◽  
Volume History

Anatomic dead space (Vd) is known to increase with end-inspiratory lung volume (EILV), and the gradient of the relationship has been proposed as an index of airway distensibility (ΔVd). The aims of this study were to apply a rapid method for measuring ΔVd and to determine whether it was affected by lung volume history. Vd of 16 healthy and 16 mildly asthmatic subjects was measured at a number of known EILVs by using a tidal breathing, CO2-washout method. The effect of lung volume history was assessed by using three tidal breathing regimens: 1) three discrete EILVs (low/medium/high; LMH); 2) progressively decreasing EILVs from total lung capacity (TLC; TLC-RV); and 3) progressively increasing EILVs from residual volume (RV; RV-TLC). ΔVd was lower in the asthmatic group for the LMH (25.3 ± 2.24 vs. 21.2 ± 1.66 ml/l, means ± SE) and TLC-RV (24.3 ± 1.69 vs. 18.7 ± 1.16 ml/l) regimens. There was a trend for a lower ΔVd in the asthmatic group for the RV-TLC regimen (23.3 ± 2.19 vs. 18.8 ± 1.68 ml/l). There was no difference in ΔVd between groups. In conclusion, mild asthmatic subjects have stiffer airways than normal subjects, and this is not obviously affected by lung volume history.

Topographical distribution of regional lung volume in anesthetized dogs

1983 ◽  
Vol 54 (4) ◽  
pp. 1048-1056 ◽  
Author(s):  
R. D. Hubmayr ◽  
B. J. Walters ◽  
P. A. Chevalier ◽  
J. R. Rodarte ◽  
L. E. Olson
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Important Determinant ◽  
Body Position ◽  
Lower Lobe ◽  
Lung Capacity ◽  
Topographical Distribution ◽  
Regional Lung ◽  
Residual Capacity ◽  
Anesthetized Dogs

The distribution of regional lung volume during static deflation from total lung capacity to functional residual capacity was determined from the positions of intraparenchymal metallic markers ascertained by a biplane video roentgenographic technique in supine and prone anesthetized dogs. Regional lung volumes were linearly related to overall lung volume so that regional volume could be characterized by a ventilation index (VI), which is the ventilation per alveolus relative to the ventilation of the overall lung. For the supine position, there were vertical and cephalocaudal gradients in VI in both the upper and lower lobes. Mean VI was greater in the lower lobe than in the upper lobe, but VI was less than would be predicted from extrapolation of the upper lobe relationship. For the prone position, there was no consistent gradient in VI in any direction. The magnitude of the gradients in VI and the effects of body position suggest that, in the recumbent dog, the thoracic cavity shape is a more important determinant of regional lung volume than is the effect of gravity on the lung itself.

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