Effect of body position on regional diaphragm function in dogs

1990 ◽  
Vol 69 (6) ◽  
pp. 2296-2302 ◽  
Author(s):  
J. Sprung ◽  
C. Deschamps ◽  
S. S. Margulies ◽  
R. D. Hubmayr ◽  
J. R. Rodarte
Keyword(s):  
Prone Position ◽  
Regional Differences ◽  
Body Position ◽  
Vertical Gradient ◽  
Transdiaphragmatic Pressure ◽  
Lung Capacity ◽  
Volume Relationship ◽  
Residual Capacity ◽  
Fractional Shortening

The in situ lengths of muscle bundles of the crural and three regions of the costal diaphragm between origin and insertion were determined with a video roentgenographic technique in dogs. At total lung capacity (TLC) in both the prone and supine positions, the length of the diaphragm is not significantly different from the unstressed excised length, suggesting that the diaphragm is not under tension at TLC and that there is a hydrostatic gradient of pleural pressure on the diaphragmatic surface. Except for the ventral region of the costal diaphragm, which does not change length at lung volumes greater than 70% TLC, all other regions are stretched during passive deflations from TLC. Therefore below TLC the diaphragm is under passive tension and supports a transdiaphragmatic pressure (Pdi). The length of the diaphragm relative to its unstressed length is not uniform at functional residual capacity (FRC) and does not follow a strict vertical gradient that reverses when the animal is changed from the supine to the prone position. By inference, the length of muscle bundles is determined by factors other than the vertical gradient of Pdi. During mechanical ventilation, regional shortening is identical to the passive deflation length-volume relationship near FRC. Prone and supine FRC is the same, but the diaphragm is slightly shorter in the prone position. In both positions, during spontaneous ventilation there are no consistent differences in regional fractional shortening, despite regional differences in initial length relative to unstressed length.

Effects of body position and lung volume on in situ operating length of canine diaphragm

1990 ◽  
Vol 69 (5) ◽  
pp. 1702-1708 ◽  
Author(s):  
S. S. Margulies ◽  
G. A. Farkas ◽  
J. R. Rodarte
Keyword(s):  
Lung Volume ◽  
Body Position ◽  
Vertical Gradient ◽  
Postoperative Recovery ◽  
Optimal Force ◽  
Residual Capacity ◽  
Crural Diaphragm

The performance of the diaphragm is influenced by its in situ length relative to its optimal force-generating length (Lo). Lead markers were sutured to the abdominal surface of the diaphragm along bundles of the left ventral, middle, and dorsal regions of the costal diaphragm and the left crural diaphragm of six beagle dogs. After 2-3 wk postoperative recovery, the dogs were anesthetized, paralyzed, and scanned prone and supine in the Dynamic Spatial Reconstructor (DSR) at a total lung capacity (TLC), functional residual capacity (FRC), and residual volume (RV). The location of each marker was digitized from the reconstructed DSR images, and in situ lengths were determined. After an overdose of anesthetic had been administered to the dogs, each marked diaphragm bundle was removed, mounted in a 37 degrees C in vitro chamber, and adjusted to Lo (maximum tetanic force). The operating length of the diaphragm, or in situ length expressed as percent Lo, varied from region to region at the lung volumes studied; variability was least at RV and increased with increasing lung volume. At FRC, all regions of the diaphragm was shorter in the prone posture compared with the supine, but there was no clear gravity-dependent vertical gradient of in situ length in either posture. Because in vitro length-tension characteristics were similar for all diaphragm regions, regional in vivo length differences indicate that the diaphragm's potential to generate maximal force is nonuniform.

Effect of lung inflation on regional lung expansion in supine and prone rabbits

1991 ◽  
Vol 71 (1) ◽  
pp. 76-82 ◽  
Author(s):  
Q. H. Yang ◽  
S. J. Lai-Fook
Keyword(s):  
Prone Position ◽  
Functional Residual Capacity ◽  
Supine Position ◽  
Vertical Gradient ◽  
Lung Inflation ◽  
Lung Expansion ◽  
Isolated Lung ◽  
Residual Capacity ◽  
Lung Deflation

At functional residual capacity, lung expansion is more uniform in the prone position than in the supine position. We examined the effect of positive airway pressure (Paw) on this position-dependent difference in lung expansion. In supine and prone rabbits postmortem, we measured alveolar size through dependent and nondependent pleural windows via videomicroscopy at Paw of 0 (functional residual capacity), 7, and 15 cmH2O. After the chest was opened, alveolar size was measured in the isolated lung at several transpulmonary pressures (Ptp) on lung deflation. Alveolar mean linear intercept (Lm) was measured from the video images taken in situ. This was compared with those measured in the isolated lung to determine Ptp in situ. In the supine position, the vertical Ptp gradient increased from 0.52 cmH2O/cm at 0 cmH2O Paw to 0.90 cmH2O/cm at 15 cmH2O Paw, while the vertical gradient in Lm decreased from 2.17 to 0.80 microns/cm. In the prone position, the vertical Ptp gradient increased from 0.06 cmH2O/cm at 0 cmH2O Paw to 0.35 cmH2O/cm at 15 cmH2O Paw, but there was no change in the vertical Lm gradient. In anesthetized paralyzed rabbits in supine and prone positions, we measured pleural liquid pressure directly at 0, 7, and 15 cmH2O Paw with dependent and nondependent rib capsules. Vertical Ptp gradients measured with rib capsules were similar to those estimated from the alveolar size measurements. Lung inflation during mechanical ventilation may reduce the vertical nonuniformities in lung expansion observed in the supine position, thereby improving gas exchange and the distribution of ventilation.

Kinematics and mechanics of midcostal diaphragm of dog

1997 ◽  
Vol 83 (4) ◽  
pp. 1068-1075 ◽  
Author(s):  
Aladin M. Boriek ◽  
Joseph R. Rodarte ◽  
Theodore A. Wilson
Keyword(s):  
Functional Residual Capacity ◽  
Spontaneous Breathing ◽  
Total Lung Capacity ◽  
Radius Of Curvature ◽  
Transdiaphragmatic Pressure ◽  
Lung Capacity ◽  
Circular Arcs ◽  
Residual Capacity ◽  
Three Bundles ◽  
Marker Location

Boriek, Aladin M., Joseph R. Rodarte, and Theodore A. Wilson. Kinematics and mechanics of midcostal diaphragm of dog. J. Appl. Physiol. 83(4): 1068–1075, 1997.—Radiopaque markers were attached to the peritoneal surface of three neighboring muscle bundles in the midcostal diaphragm of four dogs, and the locations of the markers were tracked by biplanar video fluoroscopy during quiet spontaneous breathing and during inspiratory efforts against an occluded airway at three lung volumes from functional residual capacity to total lung capacity in both the prone and supine postures. Length and curvature of the muscle bundles were determined from the data on marker location. Muscle lengths for the inspiratory states, as a fraction of length at functional residual capacity, ranged from 0.89 ± 0.04 at end inspiration during spontaneous breathing down to 0.68 ± 0.07 during inspiratory efforts at total lung capacity. The muscle bundles were found to have the shape of circular arcs, with the three bundles forming a section of a right circular cylinder. With increasing lung volume and diaphragm displacement, the circular arcs rotate around the line of insertion on the chest wall, the arcs shorten, but the radius of curvature remains nearly constant. Maximal transdiaphragmatic pressure was calculated from muscle curvature and maximal tension-length data from the literature. The calculated maximal transdiaphragmatic pressure-length curve agrees well with the data of Road et al. ( J. Appl. Physiol. 60: 63–67, 1986).

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

Mechanical implications of in vivo human diaphragm shape

1992 ◽  
Vol 72 (4) ◽  
pp. 1407-1412 ◽  
Author(s):  
M. Paiva ◽  
S. Verbanck ◽  
M. Estenne ◽  
B. Poncelet ◽  
C. Segebarth ◽  
...  
Keyword(s):  
Surface Area ◽  
Functional Residual Capacity ◽  
Three Dimensional ◽  
Vertical Gradient ◽  
Total Surface Area ◽  
Diaphragm Muscle ◽  
Posterior Half ◽  
Transdiaphragmatic Pressure ◽  
Residual Capacity

Using magnetic resonance imaging, we measured the three-dimensional form of the diaphragm in vivo in four supine relaxed subjects at functional residual capacity and calculated its total surface area, the right and left surface areas in the zone of apposition, and the principal radii of curvature as a function of height. The area of apposition comprised 45 +/- 1.5% (SE) of the total surface area of the diaphragm. Available data on the area of the central tendon indicate that a considerable part of the muscular part of the diaphragm is lung apposed. The curvature was linearly related to height over 7 cm of the posterior half of each hemidiaphragm. From the linear portion of this graph and assuming a vertical gradient of transdiaphragmatic pressure of 0.75 cmH2O/cm, we applied the Laplace law and calculated tensions of 54 and 32 g/cm for right and left sides, respectively. We conclude that the shape of at least part of the posterior half of the relaxed human diaphragm in the supine position at functional residual capacity can be explained by the Laplace law, suggesting that both the lung and abdominal contents behave sufficiently as fluids so that they do not impose their shape on the diaphragm. Because diaphragm muscle is partly lung apposed, it is unlikely that the diaphragm functions simply as a piston.

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.

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.

Pleural liquid pressure measured with rib capsules in anesthetized ponies

1988 ◽  
Vol 64 (1) ◽  
pp. 102-107 ◽  
Author(s):  
L. E. Olson ◽  
S. J. Lai-Fook
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Body Position ◽  
Transpulmonary Pressure ◽  
Vertical Gradient ◽  
Liquid Pressure ◽  
Minimal Distortion ◽  
Poor Ventilation ◽  
Spontaneously Breathing ◽  
Pleural Liquid Pressure

Pleural liquid pressure was measured at end expiration in 11 spontaneously breathing anesthetized ponies in the prone and supine positions. A liquid-filled capsule was implanted into a rib to measure pleural liquid pressure with minimal distortion of the pleural space (Wiener-Kronish et al., J. Appl. Physiol. 59: 597-602, 1985). Capsule position relative to lung height was measured from thoracic radiographs taken in each position. In each body position, pleural liquid pressure was most negative in the superior lung regions and least negative in the inferior lung regions. In the supine position, the magnitude of the vertical gradient in pleural liquid pressure was 0.67 cmH2O/cm ht and was not significantly different from 1 cmH2O/cm ht. In the inferior lung regions (less than 50% lung ht), pleural liquid pressure averaged -1.3 cmH2O, indicating a low transpulmonary pressure over the region of the chest where most of the lung mass is located. When animals were in the prone position, the magnitude of the vertical gradient in pleural liquid pressure was 0.14 cmH2O/cm ht and was not statistically different from 0 cmH2O/cm ht. In each body position, mean transpulmonary pressure, measured postmortem, was similar to the estimated magnitude of pleural liquid pressure at 50% lung ht. This suggests that pleural liquid pressure is closely related to pleural surface pressure. These results are consistent with the poor ventilation distribution and reduced lung volumes measured in anesthetized horses in the supine position compared with values measured in horses in the prone position.

Stability of evoked parasternal intercostal muscle electromyogram at increased end-expiratory lung volume

1995 ◽  
Vol 78 (4) ◽  
pp. 1485-1488 ◽  
Author(s):  
J. D. Road ◽  
S. Osborne ◽  
A. Cairns
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Body Position ◽  
Muscle Length ◽  
Length Change ◽  
Intercostal Nerve ◽  
Electromyographic Activity ◽  
Intercostal Muscle ◽  
Lung Capacity ◽  
Residual Capacity

The diaphragmatic electromyogram has been measured as an index of the level of diaphragmatic activation. The diaphragmatic electromyogram, however, even when measured by intramuscular electrodes, can be artifactually altered by a change in lung volume (A. Brancatisano, S. M. Kelly, A. Tully, S. H. Loring, and L. A. Engel. J. Appl. Physiol. 66: 1699–1705, 1989) or by a change in body position. The parasternal intercostal muscle may be less subject to the mechanisms that are believed to produce this artifactual change. We asked whether the parasternal intercostal electromyographic activity could be reliable when lung volume changes. Six supine rabbits were anesthetized with ketamine and xylazine. Fine bipolar copper wires, with their tips exposed, were inserted into the left parasternal intercostal muscle in the third interspace. A stimulus that was three times maximal was applied to the corresponding intercostal nerve, and the resulting action potential (AP) was photographed. Parasternal intercostal muscle length was measured by sonomicrometry over the vital capacity range. There were small nonsignificant changes in the AP from functional residual capacity (FRC) to total lung capacity. From FRC to residual volume there was variation in the AP. The AP was also quite stable when regional conductivity was altered but showed variation when the parasternal intercostal muscle length change was accentuated by traction on the rib cage. We conclude that the parasternal intercostal electromyographic activity can be reliably used to measure inspiratory motoneuron output to it over the range of lung volumes from FRC to total lung capacity.

Diaphragm thickness heterogeneity at functional residual capacity and total lung capacity

1995 ◽  
Vol 78 (3) ◽  
pp. 1030-1036 ◽  
Author(s):  
J. L. Wait ◽  
D. Staworn ◽  
D. C. Poole
Keyword(s):  
Functional Residual Capacity ◽  
Total Lung Capacity ◽  
Diaphragm Thickness ◽  
Rib Cage ◽  
Lung Capacity ◽  
Significant Difference ◽  
Residual Capacity ◽  
Radial Thickness ◽  
Tendon Insertion

One of the determinants of muscular force is the number of myofibrils in parallel, which is approximated by thickness. To better understand the heterogeneity of diaphragm thickness, we quantified the interregional and radial patterns of thickness of nine canine diaphragms rapidly perfusion fixed in situ with glutaraldehyde at functional residual capacity (FRC) (n = 6) and total lung capacity (TLC) (n = 3). Thickness was determined gravimetrically from punch biopsies radiating from the central tendon to rib cage insertion in ventral, middle, and dorsal costal and crural regions. For comparison, the contralateral unfixed hemidiaphragm was sampled in the same fashion. The findings of this investigation include the following. 1) The costal diaphragm exhibits the same pattern of interregional heterogeneity at FRC, TLC, and in the freshly excised state. 2) The costal diaphragm is significantly thinner at FRC in situ (0.17 +/- 0.01 cm) than is the freshly excised contralateral diaphragm (0.21 +/- 0.01 cm; P < 0.05), whereas there is no significant difference between thickness at TLC and the freshly excised state. 3) There is significant, previously underscribed, radial tapering from the rib cage attachment (0.24 +/- 0.02) to the central tendon insertion (0.15 +/- 0.01 cm; P < 0.05) that is exaggerated at TLC. 4) With passive inflation from FRC to TLC, the greatest increase in thickness occurs close to the rib cage attachment for the ventral and medial costal regions but close to the central tendon in the dorsal and crural regions. We conclude that the diaphragm at FRC and TLC exhibits radial thickness heterogeneity that cannot be predicted from dimensions of the freshly excised diaphragm.(ABSTRACT TRUNCATED AT 250 WORDS)

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