Effect of respiratory muscle tension on lung volume

1992 ◽  
Vol 73 (6) ◽  
pp. 2283-2288 ◽  
Author(s):  
T. A. Wilson ◽  
A. De Troyer
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Airway Pressure ◽  
Linear Prediction ◽  
Muscle Tension ◽  
Muscle Length ◽  
Respiratory Muscles ◽  
Active Tension ◽  
Airway Opening ◽  
Measured Change

The chest wall is modeled as a linear system for which the displacements of points on the chest wall are proportional to the forces that act on the chest wall, namely, airway opening pressure and active tension in the respiratory muscles. A standard theorem of mechanics, the Maxwell reciprocity theorem, is invoked to show that the effect of active muscle tension on lung volume, or airway pressure if the airway is closed, is proportional to the change of muscle length in the relaxation maneuver. This relation was tested experimentally. The shortening of the cranial-caudal distance between a rib pair and the sternum was measured during a relaxation maneuver. These data were used to predict the respiratory effect of forces applied to the ribs and sternum. To test this prediction, a cranial force was applied to the rib pair and a caudal force was applied to the sternum, simulating the forces applied by active tension in the parasternal intercostal muscles. The change in airway pressure, with lung volume held constant, was measured. The measured change in airway pressure agreed well with the prediction. In some dogs, nonlinear deviations from the linear prediction occurred at higher loads. The model and the theorem offer the promise that existing data on the configuration of the chest wall during the relaxation maneuver can be used to compute the mechanical advantage of the respiratory muscles.

Mechanical advantage of sternomastoid and scalene muscles in dogs

1997 ◽  
Vol 82 (5) ◽  
pp. 1517-1522 ◽  
Author(s):  
Alexandre Legrand ◽  
Vincent Ninane ◽  
André De Troyer
Keyword(s):  
Muscle Mass ◽  
Muscle Tension ◽  
Muscle Length ◽  
Respiratory Muscles ◽  
Maximal Effect ◽  
Relaxation Length ◽  
Cross Sectional ◽  
Mechanical Advantage ◽  
Airway Opening ◽  
Anesthetized Dogs

Legrand, Alexandre, Vincent Ninane, and André De Troyer. Mechanical advantage of sternomastoid and scalene muscles in dogs. J. Appl. Physiol. 82(5): 1517–1522, 1997.—Theoretical studies have led to the prediction that the maximal effect of a given respiratory muscle on airway opening pressure (Pao) is the product of muscle mass, the maximal active muscle tension per unit cross-sectional area, and the fractional change in muscle length per unit volume increase of the relaxed chest wall. It has previously been shown that the parasternal intercostals behave in agreement with this prediction (A. De Troyer, A. Legrand, and T. A. Wilson. J. Physiol. (Lond.) 495: 239–246, 1996; A. Legrand, T. A. Wilson, and A. De Troyer. J. Appl. Physiol. 80: 2097–2101, 1996). In the present study, we have tested the prediction further by measuring the response to passive inflation and the pressure-generating ability of the sternomastoid and scalene muscles in eight anesthetized dogs. With 1-liter passive inflation, the sternomastoids and scalenes shortened by 2.03 ± 0.17 and 5.98 ± 0.43%, respectively, of their relaxation length ( P < 0.001). During maximal stimulation, the two muscles caused similar falls in Pao. However, the sternomastoids had greater mass such that the change in Pao (ΔPao) per unit muscle mass was −0.19 ± 0.02 cmH2O/g for the scalenes and only −0.07 ± 0.01 cmH2O/g for the sternomastoids ( P < 0.001). After extension of the neck, there was a reduction in both the muscle shortening during passive inflation and the fall in Pao during stimulation. The ΔPao per unit muscle mass was thus closely related to the change in length; the slope of the relationship was 3.1. These observations further support the concept that the fractional changes in length of the respiratory muscles during passive inflation can be used to predict their pressure-generating ability.

Static features of the passive rib cage and abdomen-diaphragm

1965 ◽  
Vol 20 (6) ◽  
pp. 1187-1193 ◽  
Author(s):  
Emilio Agostoni ◽  
Piero Mognoni ◽  
Giorgio Torri ◽  
Ada Ferrario Agostoni
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Vital Capacity ◽  
Small Volume ◽  
Respiratory Muscles ◽  
Muscular Activity ◽  
Pressure Curve ◽  
Rib Cage ◽  
Expiratory Muscles ◽  
Volume Pressure Curves

The static relation between lung volume and rib cage circumference has been determined over the vital capacity range, during relaxation and activity of the respiratory muscles with open airway. At small volume the circumference is larger during relaxation; the reverse occurs at large volume. During relaxation at full expiration the cross section of the rib cage becomes more elliptical and in some subjects also greater. Hence the shape of the chest wall during muscular activity is different from that during relaxation. Because of this change of chest wall shape the outward recoil of the passive rib cage at full expiration, in the seven subjects examined, is higher than that given by the conventional volume-pressure curve during relaxation. The volume displacements of the rib cage and of the abdomen-diaphragm have been calculated and the volume-pressure curves of the passive rib cage and abdomen-diaphragm have been constructed, taking into account the changes of the chest wall shape occurring during relaxation. change of chest wall shape during relaxation; relation between lung volume and rib cage circumference during relaxation; relation between pleural pressure and rib cage circumference during relaxation; recoil of the passive rib cage; pressure exerted by the expiratory muscles at full expiration; volume-pressure curve of the passive rib cage; volume-pressure curve of the passive abdomen-diaphragm Submitted on September 14, 1964

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

1993 ◽  
Vol 74 (5) ◽  
pp. 2286-2293 ◽  
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.

Effect of acceleration on the chest wall

1994 ◽  
Vol 76 (3) ◽  
pp. 1242-1246 ◽  
Author(s):  
T. A. Wilson ◽  
S. Liu
Keyword(s):  
Experimental Study ◽  
Chest Wall ◽  
Functional Residual Capacity ◽  
Lung Volume ◽  
Airway Pressure ◽  
Gravitational Force ◽  
Respiratory Effect ◽  
Rib Cage ◽  
Modeling And Analysis ◽  
Residual Capacity

The gravitational force on the rib cage has been found to be an expiratory force of approximately 8 cmH2O. The gravitational force on the abdomen is an inspiratory force of the same magnitude. Because the compliance of the rib cage is greater than the compliance of the abdomen, it follows that gravity has a net expiratory effect on lung volume and that upward accelerations augmenting the gravitational force would have an additional expiratory effect. This conclusion is contrary to observations that functional residual capacity increases during headward accelerations in centrifuges and during intervals of upward acceleration in airplanes. We report the results of two studies of the effects of accelerations that are smaller in magnitude and of shorter duration than those studied in centrifuges and airplanes. The first was an experimental study of the effect of acceleration in an elevator. In subjects who relaxed against an occluded airway, airway pressure increased during upward accelerations and decreased during downward accelerations. The second was the modeling and analysis of the effects of the accelerations that occur during walking. The analysis predicted an initial expiratory response to the acceleration spike that occurs during footfall. The prediction agreed with data in the literature on the respiratory effect of walking. In both of these studies upward accelerations had an expiratory effect.

Determinants of transdiaphragmatic pressure in dogs

1990 ◽  
Vol 69 (6) ◽  
pp. 2050-2056 ◽  
Author(s):  
R. D. Hubmayr ◽  
J. Sprung ◽  
S. Nelson
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Lung Volume ◽  
Abdominal Cavity ◽  
Muscle Length ◽  
Mechanical Efficiency ◽  
Force Output ◽  
Experimental Conditions ◽  
Transdiaphragmatic Pressure ◽  
Wall Geometry

We measured the transdiaphragmatic pressure (Pdi) during bilateral phrenic nerve stimulation and evaluated the determinants of its change with lung volume, chest wall geometry, and respiratory system impedance in supine dogs. Four rows of radiopaque markers were sewn onto muscle bundles of the costal and crural diaphragm between their origin on the central tendon and their insertion on the rib cage and spine. The length of the diaphragm (L) was determined from the projection images of marker rows using biplane fluoroscopy. Measurements were made at lung volumes between total lung capacity and functional residual capacity before and after the infusion of Ringer lactate solution into the abdominal cavity. In contrast to relaxation, during tetanic stimulation the active lengths of the muscle bundles were similar at all volumes, but the diaphragm assumed different shapes. Although the small differences in active muscle length with volume and liquid loads are consistent with only small changes in muscle force output, Pdi varied by a factor of greater than or equal to 5. There was no single L/Pdi curve that fitted all data during 50-Hz stimulations. We conclude that under these experimental conditions Pdi is not a unique measure of the force produced by the diaphragm and that lung volume, chest wall geometry, and respiratory system impedance are important determinants of the mechanical efficiency of the diaphragm as a pressure generator.

Muscle kinematics for minimal work of breathing

1999 ◽  
Vol 87 (2) ◽  
pp. 554-560 ◽  
Author(s):  
Theodore A. Wilson ◽  
Maurizio Angelillo ◽  
Alexandre Legrand ◽  
André de Troyer
Keyword(s):  
Chest Wall ◽  
Muscle Activation ◽  
Work Of Breathing ◽  
Muscle Length ◽  
Respiratory Muscles ◽  
Quiet Breathing ◽  
Inspiratory Muscles ◽  
Lung Expansion ◽  
Muscle Shortening ◽  
Minimal Work

A mathematical model was analyzed to obtain a quantitative and testable representation of the long-standing hypothesis that the respiratory muscles drive the chest wall along the trajectory for which the work of breathing is minimal. The respiratory system was modeled as a linear elastic system that can be expanded either by pressure applied at the airway opening (passive inflation) or by active forces in respiratory muscles (active inflation). The work of active expansion was calculated, and the distribution of muscle forces that produces a given lung expansion with minimal work was computed. The calculated expression for muscle force is complicated, but the corresponding kinematics of muscle shortening is simple: active inspiratory muscles shorten more during active inflation than during passive inflation, and the ratio of active to passive shortening is the same for all active muscles. In addition, the ratio of the minimal work done by respiratory muscles during active inflation to work required for passive inflation is the same as the ratio of active to passive muscle shortening. The minimal-work hypothesis was tested by measurement of the passive and active shortening of the internal intercostal muscles in the parasternal region of two interspaces in five supine anesthetized dogs. Fractional changes in muscle length were measured by sonomicrometry during passive inflation, during quiet breathing, and during forceful inspiratory efforts against a closed airway. Active muscle shortening during quiet breathing was, on average, 70% greater than passive shortening, but it was only weakly correlated with passive shortening. Active shortening inferred from the data for more forceful inspiratory efforts was ∼40% greater than passive shortening and was highly correlated with passive shortening. These data support the hypothesis that, during forceful inspiratory efforts, muscle activation is coordinated so as to expand the chest wall with minimal work.

Effect of inflation on the interaction between the left and right hemidiaphragms

2005 ◽  
Vol 99 (4) ◽  
pp. 1301-1307 ◽  
Author(s):  
André De Troyer ◽  
Matteo Cappello ◽  
Pierre Scillia
Keyword(s):  
Lung Volume ◽  
Muscle Tension ◽  
Abdominal Pressure ◽  
Lung Volumes ◽  
Radiographic Measurements ◽  
Airway Opening ◽  
Residual Capacity ◽  
Left And Right ◽  
Predicted Values ◽  
Pressure Changes

At resting end expiration [functional residual capacity (FRC)], the actions of the left and right hemidiaphragms on the lung are synergistic. However, the synergism decreases in magnitude as muscle tension decreases. Therefore, the hypothesis was tested in anesthetized dogs that the degree of synergism between the two hemidiaphragms also decreases with increasing lung volume. In a first experiment, the changes in airway opening pressure (ΔPao) and abdominal pressure (ΔPab) obtained during simultaneous stimulation of the left and right phrenic nerves (measured changes in pressure) at different lung volumes were compared with the sum of the pressure changes produced by their separate stimulation (predicted changes in pressure). Although the pressure changes decreased markedly with increasing lung volume, the measured ΔPao and ΔPab were substantially greater than the predicted values at all lung volumes. The ratio of the measured to the predicted ΔPao, in fact, remained constant. In a second experiment, radiographic measurements showed that the fractional shortening of the muscle during bilateral contraction at high lung volumes was similar to that during unilateral contraction. During unilateral contraction at high lung volumes, however, the passive hemidiaphragm moved in the cranial direction, whereas, during unilateral contraction at FRC, it moved in the caudal direction. These observations indicate that 1) for a given muscle tension, the synergism between the two halves of the diaphragm is greater at high lung volumes than at FRC; and 2) this difference is primarily related to the greater distortion of the muscle configuration.

scholarly journals Mechanical advantage of the canine triangularis sterni

1998 ◽  
Vol 84 (2) ◽  
pp. 562-568 ◽  
Author(s):  
André De Troyer ◽  
Alexandre Legrand
Keyword(s):  
Geometric Analysis ◽  
Muscle Length ◽  
Respiratory Muscles ◽  
Linear Increase ◽  
Maximal Effect ◽  
Volume Increase ◽  
Rib Cage ◽  
Inspiratory Muscles ◽  
Airway Opening ◽  
Residual Capacity

De Troyer, André, and Alexandre Legrand.Mechanical advantage of the canine triangularis sterni. J. Appl. Physiol. 84(2): 562–568, 1998.—Recent studies on the canine parasternal intercostal, sternomastoid, and scalene muscles have shown that the maximal changes in airway opening pressure (ΔPao) obtained per unit muscle mass (ΔPao/ m) during isolated contraction are closely related to the fractional changes in muscle length per unit volume increase of the relaxed chest wall. In the present study, we have examined the validity of this relationship for the triangularis sterni, an important expiratory muscle of the rib cage in dogs. Passive inflation above functional residual capacity (FRC) induced a virtually linear increase in muscle length, such that, with a 1.0-liter inflation, the muscle lengthened by 17.9 ± 1.6 (SE) % of its FRC length. When the muscle in one interspace was maximally stimulated at FRC, Pao increased by 0.84 ± 0.11 cmH2O. However, in agreement with the length-tension characteristics of the muscle, when lung volume was increased by 1.0 liter before stimulation, the rise in Pao amounted to 1.75 ± 0.12 cmH2O. At the higher volume, ΔPao/ m therefore averaged + 0.53 ± 0.05 cmH2O/g, such that the coefficient of proportionality between the change in triangularis sterni length during passive inflation and ΔPao/ mwas the same as that previously obtained for the parasternal intercostal and neck inspiratory muscles. These observations, therefore, confirm that there is a unique relationship between the fractional changes in length of the respiratory muscles, both inspiratory and expiratory, during passive inflation and their ΔPao/ m. Consequently, the maximal effect of a particular muscle on the lung can be predicted on the basis of its change in length during passive inflation and its mass. A geometric analysis of the rib cage also established that the lengthening of the canine triangularis sterni during passive inflation is much greater than the shortening of the parasternal intercostals because, in dogs, the costal cartilages slope downward from the sternum.

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