Mechanism of the increased rib cage expansion produced by the diaphragm with abdominal support

2015 ◽  
Vol 118 (8) ◽  
pp. 989-995 ◽  
Author(s):  
André De Troyer ◽  
Theodore A. Wilson
Keyword(s):  
Abdominal Wall ◽  
Pleural Pressure ◽  
Vector Analysis ◽  
Abdominal Pressure ◽  
Mechanical Support ◽  
Rib Cage ◽  
Intercostal Muscles ◽  
Anesthetized Dogs ◽  
External Forces

When the abdomen in quadriplegic subjects is given a passive mechanical support, the expansion of the lower rib cage during inspiration is greater and the inward displacement of the upper rib cage is smaller. These changes have traditionally been attributed to an increase in the appositional force of the diaphragm, but the mechanisms have not been assessed. In this study, the inspiratory intercostal muscles in all interspaces were severed in anesthetized dogs, so that the diaphragm was the only muscle active during inspiration, and the displacements of the ribs 10 and 5 and the changes in pleural and abdominal pressure were measured during unimpeded breathing and during breathing with a plate applied on the ventral abdominal wall. In addition, external forces were applied to the 10th rib pair in the cranial and lateral directions, and the rib trajectories thus obtained were used as the basis for a vector analysis to estimate the relative contributions of the insertional and appositional forces to the rib 10 displacements during breathing. Application of the abdominal plate caused a marked increase in the inspiratory cranial and outward displacement of rib 10 and a decrease in the inspiratory caudal displacement of rib 5. Analysis of the results showed, however, that 1) the insertional and appositional forces contributed nearly equally to the increased inspiratory displacement of rib 10 and 2) the decrease in the expiratory displacement of rib 5 was the result of both the greater displacement of the lower ribs and the decrease in pleural pressure.

Pleural pressure increases during inspiration in the zone of apposition of diaphragm to rib cage

1988 ◽  
Vol 65 (5) ◽  
pp. 2207-2212 ◽  
Author(s):  
W. F. Urmey ◽  
A. De Troyer ◽  
K. B. Kelly ◽  
S. H. Loring
Keyword(s):  
Esophageal Pressure ◽  
Pleural Pressure ◽  
Abdominal Pressure ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Direct Measurements ◽  
Anesthetized Dogs ◽  
Theoretical Mechanism ◽  
Phrenic Stimulation ◽  
Anatomic Region

The zone of apposition of diaphragm to rib cage provides a theoretical mechanism that may, in part, contribute to rib cage expansion during inspiration. Increases in intra-abdominal pressure (Pab) that are generated by diaphragmatic contraction are indirectly applied to the inner rib cage wall in the zone of apposition. We explored this mechanism, with the expectation that pleural pressure in this zone (Pap) would increase during inspiration and that local transdiaphragmatic pressure in this zone (Pdiap) must be different from conventionally determined transdiaphragmatic pressure (Pdi) during inspiration. Direct measurements of Pap, as well as measurements of pleural pressure (Ppl) cephalad to the zone of apposition, were made during tidal inspiration, during phrenic stimulation, and during inspiratory efforts in anesthetized dogs. Pab and esophageal pressure (Pes) were measured simultaneously. By measuring Ppl's with cannulas placed through ribs, we found that Pap consistently increased during both maneuvers, whereas Ppl and Pes decreased. Whereas changes in Pdi of up to -19 cmH2O were measured, Pdiap never departed from zero by greater than -4.5 cmH2O. We conclude that there can be marked regional differences in Ppl and Pdi between the zone of apposition and regions cephalad to the zone. Our results support the concept of the zone of apposition as an anatomic region where Pab is transmitted to the interior surface of the lower rib cage.

Partitioning of inspiratory pressure swings between diaphragm and intercostal/accessory muscles

1978 ◽  
Vol 44 (2) ◽  
pp. 200-208 ◽  
Author(s):  
P. T. Macklem ◽  
D. Gross ◽  
G. A. Grassino ◽  
C. Roussos
Keyword(s):  
Total Pressure ◽  
Pleural Pressure ◽  
Inspiratory Pressure ◽  
Abdominal Pressure ◽  
Abdominal Muscles ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Accessory Muscle ◽  
Inspiratory Muscles ◽  
Accessory Muscles

We tested the hypothesis that the inspiratory pressure swings across the rib-cage pathway are the sum of transdiaphragmatic pressure (Pdi) and the pressures developed by the intercostal/accessory muscles (Pic). If correct, Pic can only contribute to lowering pleural pressure (Ppl), to the extent that it lowers abdominal pressure (Pab). To test this we measured Pab and Ppl during during Mueller maneuvers in which deltaPab = 0. Because there was no outward displacement of the rib cage, Pic must have contributed to deltaPpl, as did Pdi. Under these conditions the total pressure developed by the inspiratory muscles across the rib-cage pathway was less than Pdi + Pic. Therefore, we rejected the hypothesis. A plot of Pab vs. Ppl during relaxation allows partitioning of the diaphragmatic and intercostal/accessory muscle contributions to inspiratory pressure swings. The analysis indicates that the diaphragm can act both as a fixator, preventing transmission of Ppl to the abdomen and as an agonist. When abdominal muscles remain relaxed it only assumes the latter role to the extent that Pab increases.

The two mechanisms of intercostal muscle action on the lung

2004 ◽  
Vol 96 (2) ◽  
pp. 483-488 ◽  
Author(s):  
Theodore A. Wilson ◽  
Andre De Troyer
Keyword(s):  
Three Dimensional ◽  
Intercostal Muscle ◽  
Muscle Action ◽  
Opening Pressure ◽  
Rib Cage ◽  
Intercostal Muscles ◽  
Airway Opening ◽  
The Difference ◽  
External Forces

The mechanisms of respiratory action of the intercostal muscles were studied by measuring the effect of external forces (F) applied to the ribs and by modeling the effect of F exerted by the intercostal muscles. In five dogs, with the airway occluded, cranial F were applied to individual rib pairs, from the 2nd to the 11th rib pair, and the change in airway opening pressure (Pao) was measured. The ratio Pao/F increases with increasing rib number in the upper ribs (2nd to 5th) and decreases in the lower ribs (5th to 11th). These data were incorporated into a model for the geometry of the ribs and intercostal muscles, and Pao/F was calculated from the model. For interspaces 2-8, the calculated values agree reasonably well with previously measured values. From the modeling, two mechanisms of intercostal muscle action are identified. One is the well-known Hamberger mechanism, modified to account for the three-dimensional geometry of the rib cage. This mechanism depends on the slant of an intercostal muscle relative to the ribs and on the resulting difference between the moments applied to the upper and lower ribs that bound each interspace. The second is a new mechanism that depends on the difference between the values of Pao/F for the upper and lower ribs.

Voluntary changes of thoracoabdominal shape and regional lung volumes in humans

1975 ◽  
Vol 39 (6) ◽  
pp. 997-1003 ◽  
Author(s):  
A. E. Grassino ◽  
B. Bake ◽  
R. R. Martin ◽  
R. Anthonisen
Keyword(s):  
Pressure Gradient ◽  
Negative Pressure ◽  
Degree Of Freedom ◽  
Pleural Pressure ◽  
Abdominal Pressure ◽  
Volume Distribution ◽  
Lung Volumes ◽  
Rib Cage ◽  
Regional Lung

We measured regional lung volumes from apex to base in humans during changes in thoracoabdominal shape which we monitored with magnetometers. In erect subjects, voluntary changes of shape at FRC did not change regional volume distribution. In supine subjects, the effect of negative pressure applied to the abdomen and a similar thoracoabdominal configuration achieved by voluntary means were studied. The distribution of regional volumes in both situations was the same as that measured during relaxation at the same overall lung volumes. We concluded that neither voluntary changes in shape nor negative abdominal pressure influenced the human pleural pressure gradient. This result, which differed from findings in animals, was probably because the human chest was relatively stiff and behaved with one degree of freedom; all parts of the human rib cage changed dimensions proportionally while negative abdominal pressure distorted the rib cage of animals.

Role of rib cage elastance in the coupling between the abdominal muscles and the lung

2004 ◽  
Vol 97 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Matteo Cappello ◽  
André De Troyer
Keyword(s):  
Transversus Abdominis ◽  
Abdominal Pressure ◽  
Abdominal Muscles ◽  
Transverse Diameter ◽  
Rib Cage ◽  
Mechanical Coupling ◽  
Before And After ◽  
Airway Opening ◽  
Order Of Magnitude ◽  
Anesthetized Dogs

The abdominal muscles expand the rib cage when they contract alone. This expansion opposes the deflation of the lung and may be viewed as pressure dissipation. The hypothesis was raised, therefore, that alterations in rib cage elastance should affect the lung deflating action of these muscles. To test this hypothesis and evaluate the quantitative importance of this effect, we measured the changes in airway opening pressure (Pao), abdominal pressure (Pab), and rib cage transverse diameter during isolated stimulation of the transversus abdominis muscle in anesthetized dogs, first with the rib cage intact and then after rib cage elastance was increased by clamping the ribs and the sternum. Stimulation produced increases in Pao, Pab, and rib cage diameter in both conditions. With the ribs and sternum clamped, however, the change in Pab was unchanged but the change in Pao was increased by 77% ( P < 0.001). In a second experiment, the transversus abdominis was stimulated before and after rib cage elastance was reduced by removing the bony ribs 3–8. Although the change in Pab after removal of the the ribs was still unchanged, the change in Pao was reduced by 62% ( P < 0.001). These observations, supported by a model analysis, indicate that rib cage elastance is a major determinant of the mechanical coupling between the abdominal muscles and the lung. In fact, in the dog, the effects of rib cage elastance and Pab on the lung-deflating action of the abdominal muscles are of the same order of magnitude.

Relationships between abdominal and diaphragmatic volume displacements

1991 ◽  
Vol 71 (2) ◽  
pp. 565-572 ◽  
Author(s):  
H. Knight ◽  
W. M. Petroll ◽  
D. F. Rochester
Keyword(s):  
Abdominal Wall ◽  
Geometric Model ◽  
Diaphragm Muscle ◽  
Rib Cage ◽  
Peritoneal Surface ◽  
Anesthetized Dogs ◽  
The Difference ◽  
The Relationship ◽  
Measured Volume ◽  
Volume Difference

We investigated the relationship between the volumes displaced by the diaphragm and the abdominal wall during spontaneous breathing in supine anesthetized dogs. Diaphragmatic volume displacement (Vdi) was calculated from measurements taken from anteroposterior fluoroscopic images employing a previously described geometric model. The volume displacement of the abdominal wall (Vabd) was measured with a calibrated Respitrace. Shortening of single diaphragm muscle bundles in costal and crural regions was measured as the distance between radiopaque beads sutured to the peritoneal surface of the muscle. We found that Vdi always exceeded Vabd, but Vabd/Vdi was larger in animals in which the abdominal wall was more compliant. In this preparation, Vdi is better correlated with costal than with crural shortening. Vabd did not correlate with either costal or crural shortening. We infer that the difference between Vdi and Vabd reflects the volume displacement of the lower rib cage caused by diaphragm contraction. This volume difference was tightly correlated with costal shortening. We conclude from these data that coupling between Vdi and Vabd is influenced by the relative compliances of the chest wall and abdomen. Shortening of regions of the diaphragm may have variable relationships to the measured volume displacement, but costal shortening is intimately related to expansion of the lower rib cage.

Pleural pressure between diaphragm and rib cage during inspiratory muscle activity

1988 ◽  
Vol 65 (3) ◽  
pp. 1286-1295 ◽  
Author(s):  
P. T. Macklem ◽  
L. Zocchi ◽  
E. Agostoni
Keyword(s):  
Abdominal Pressure ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Airway Occlusion ◽  
Pleural Surface ◽  
Residual Capacity ◽  
Anesthetized Dogs ◽  
Lateral Posture ◽  
Phrenic Stimulation ◽  
Different Parts

We measured the changes in pleural surface pressure (delta Ppl) in the area of apposition of the rib cage to the diaphragm (Aap) in anesthetized dogs during spontaneous breathing, inspiratory efforts after airway occlusion at functional residual capacity, and phrenic stimulation. Intact dogs were in supine or lateral posture; partially eviscerated dogs were in lateral posture. delta Ppl,ap often differed significantly from changes in abdominal pressure (delta Pab); sometimes they differed in sign (except during phrenic stimulation). Changes in transdiaphragmatic pressure in Aap (delta Pdi,ap) could be positive or negative and were less in eviscerated than in intact dogs. delta Pdi,ap could differ in sign among respiratory maneuvers and over different parts of Aap. Hence average delta Pdi,ap should be closer to zero than delta Pdi,ap at a given site. Since delta Ppl,ap = delta Prc,ap, where Prc,ap represents rib cage pressure in Aap, delta Pdi,ap = delta Pab - delta Prc,ap. Hence, considering that delta Pab and delta Prc depend on different factors, delta Pdi,ap may differ from zero. This pressure difference seems related to the interaction between two semisolid structures (contracted diaphragm and rib cage in Aap) constrained to the same shape and position.

Respiratory changes in parasternal intercostal intramuscular pressure

1990 ◽  
Vol 68 (3) ◽  
pp. 868-875 ◽  
Author(s):  
P. Leenaerts ◽  
M. Decramer
Keyword(s):  
Linear Relationship ◽  
Contractile Force ◽  
Pleural Pressure ◽  
Intramuscular Pressure ◽  
Intercostal Muscles ◽  
Airway Occlusion ◽  
Resistive Loading ◽  
Anesthetized Dogs

In an attempt to obtain insight in the forces developed by the parasternal intercostal muscles during breathing, changes in parasternal intramuscular pressure (PIP) were measured in 14 supine anesthetized dogs using a microtransducer method. In six animals, during bilateral parasternal stimulation a linear relationship between contractile force exerted on the rib and PIP was demonstrated (r greater than 0.95). In eight animals, during quiet active inspiration, substantial (55 +/- 11.5 cmH2O) PIP was developed. During inspiratory resistive loading and airway occlusion the inspiratory rise in PIP increased in proportion to the inspiratory fall in pleural pressure (r = 0.82). Phrenicotomy and vagotomy resulted in an increase in the inspiratory rise in PIP of 21% and 99%, respectively. During passive deflation, when the parasternal intercostals were passively lengthened, large rises (320 +/- 221 cmH2O) in intramuscular pressure were observed. During passive inflation intramuscular pressure remained constant or even decreased slightly (-8 +/- 25 cmH2O) as expected on the basis of the passive shortening of the muscles. PIP thus invariably increased when tension increased either actively or passively. From PIP it is clear that the parasternals exert significant forces on the ribs during respiratory maneuvers.

Action of neck accessory muscles on rib cage in dogs

1984 ◽  
Vol 56 (2) ◽  
pp. 326-332 ◽  
Author(s):  
A. De Troyer ◽  
S. Kelly
Keyword(s):  
Lung Volume ◽  
Anterior Wall ◽  
Axial Displacement ◽  
Abdominal Pressure ◽  
Rib Cage ◽  
Anesthetized Dogs ◽  
Accessory Muscles

To investigate the action of the neck accessory muscles on the rib cage, we stimulated the sternocleidomastoid and the scalenus muscles separately in supine anesthetized dogs. Hooks screwed into the sternum and ribs were used to measure their axial displacements and the changes in anteroposterior (AP) and transverse (T) diameters of the rib cage. We found that the sternocleidomastoid and scalenus muscles, when they contract alone, cause a large axial displacement of the sternum and the ribs in a cephalad direction and expand the rib cage along both its AP and T diameters. Opening the abdomen increased the cephalad displacement of the ribs and the expansion of the lower rib cage, particularly along its T diameter, but reduced the increase in lung volume. These experiments indicate 1) that the action of the sternocleidomastoid and scalenus muscles on the rib cage is essentially the consequence of a rotation of the ribs' neck axes, resulting from the cephalad displacement of the ribs, and 2) that the fall in abdominal pressure, almost certainly by acting through the zone of apposition of the diaphragm to the rib cage, has a deflationary action on the lower rib cage, more markedly so on its lateral than its anterior wall. The experiments also suggest that the fall in abdominal pressure prevents the diaphragm from moving cephalad and aids the neck accessory muscles in inflating the lungs.

Respiratory function of intercostal muscles in supine dog: an electromyographic study

1986 ◽  
Vol 60 (5) ◽  
pp. 1692-1699 ◽  
Author(s):  
A. De Troyer ◽  
V. Ninane
Keyword(s):  
Respiratory Function ◽  
Traditional View ◽  
Lower Portion ◽  
Intercostal Muscle ◽  
Muscle Action ◽  
Quiet Breathing ◽  
Rib Cage ◽  
Intercostal Muscles ◽  
Anesthetized Dogs ◽  
The Difference

It is traditionally considered that the difference in orientation of the muscle fibers makes the external intercostals elevate the ribs and the internal interosseous intercostals lower the ribs during breathing. This traditional view, however, has recently been challenged by the observation that the external and internal interosseous intercostals, when contracting alone in a single interspace, have a similar effect on the ribs into which they insert. This view has also been challenged by the observation that the external and internal intercostals in a given interspace often change their length in the same direction during breathing. In an attempt to clarify the respiratory function of these muscles, we studied eight supine lightly anesthetized dogs during quiet breathing and during static inspiratory efforts. In each animal electromyographic (EMG) recordings from the external and internal interosseous intercostals were obtained in all interspaces from the second to the eighth, and selective denervations were systematically performed to ensure with complete certainty the origin of the recorded EMG activities. The external intercostals were only activated in phase with inspiration, whereas the internal interosseous intercostals were only activated in phase with expiration. These phasic EMG activities, however, were generally small in magnitude, and the muscles were often silent. Indeed, activation of the externals was always confined to the upper portion of the rib cage, whereas activation of the internals was limited to the lower portion of the rib cage. Internal intercostal activation always occurred sequentially along a caudocephalic gradient. These observations are thus compatible with the traditional view of intercostal muscle action.(ABSTRACT TRUNCATED AT 250 WORDS)

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