Rib cage versus abdominal displacement in rabbits during forced oscillations to 30 Hz

1987 ◽  
Vol 63 (1) ◽  
pp. 309-314 ◽  
Author(s):  
B. R. Boynton ◽  
J. J. Fredberg ◽  
B. G. Buckley ◽  
I. D. Frantz
Keyword(s):  
Chest Wall ◽  
Series Resistance ◽  
Relative Displacement ◽  
Forced Oscillations ◽  
Volume Changes ◽  
Wall Model ◽  
Large Measure ◽  
Low Frequencies ◽  
Rib Cage ◽  
Experimental Findings

We measured relative displacement of the rib cage (RC) and abdomen (ABD) in 12 anesthetized rabbits during forced oscillations. Sinusoidal volume changes were delivered through a tracheostomy at frequencies from 0.5 to 30 Hz and measured by body plethysmography. Displacements of the RC and ABD were measured by inductive plethysmography. During oscillation at fixed tidal volume (VT = 1.3 ml/kg) the ratio ABD/RC, normalized to unity at 0.5 Hz, was 0.88 +/- 0.06 at 2 Hz and increased to 1.28 +/- 0.13 at 6 Hz (P less than 0.01). As frequency increased further ABD/RC fell sharply but between 20 and 30 Hz reached a plateau of 0.17 +/- 0.02 (P less than 0.001). Displacements of RC and ABD were nearly synchronous from 0.5 to 2 Hz, but as frequency increased ABD lagged RC progressively, reaching a phase difference of 90 degrees between 6 and 8 Hz and 180 degrees between 16 and 20 Hz. In six additional rabbits we measured chest wall displacements while varying VT from 0.5 to 3.7 ml/kg. ABD/RC was independent of VT at low frequencies (less than or equal to 6 Hz) but fell sharply with increasing VT at the higher frequencies. We interpreted these findings using a chest wall model having an RC compartment whose displacements are governed primarily by a nonlinear compliance, in parallel with an ABD compartment whose displacements are governed by a series resistance, inertance, and in addition a nonlinear compliance. The experimental findings are in large measure accounted for by such a model if the degree of nonlinearity of ABD and RC compliances are comparable.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanical impedances of lungs and chest wall in the cat

1992 ◽  
Vol 73 (2) ◽  
pp. 427-433 ◽  
Author(s):  
Z. Hantos ◽  
A. Adamicza ◽  
E. Govaerts ◽  
B. Daroczy
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Small Volume ◽  
Angular Frequency ◽  
Forced Oscillations ◽  
Amplitude Dependence ◽  
Volume Changes ◽  
The Real ◽  
Output Flow ◽  
Frequency Independent

In nine anesthetized and paralyzed cats, the mechanical impedances of the total respiratory system (Zrs) and the lungs (ZL) were measured with small-volume pseudorandom forced oscillations between 0.2 and 20 Hz. ZL was measured after thoracotomy, and chest wall impedance (Zw) was calculated as Zw = Zrs-ZL. All impedances were determined by using input airflow [input impedance (Zi)] and output flow measured with a body box [transfer impedance (Zt)]. The differences between Zi and Zt were small for Zrs and negligible for ZL. At 0.2 Hz, the real and imaginary parts of ZL amounted to 33 +/- 4 and 35 +/- 3% (SD), respectively, of Zrs. Up to 8 Hz, all impedances were consistent with a model containing a frequency-independent resistance and inertance and a constant-phase tissue part (G-jH)/omega alpha, where G and H are coefficients for damping and elastance, respectively, omega is angular frequency, and alpha determines the frequency dependence of the real and imaginary parts. G/H was higher for Zw than for ZL (0.29 +/- 0.05 vs. 0.22 +/- 0.04, P less than 0.01). In four cats, the amplitude dependence of impedances was studied: between oscillation volumes of 0.8 and 3 ml, GL, HL, Gw, and Hw decreased on average by 3, 9, 26, and 29%, respectively, whereas the change in G/H was small for both ZL (7%) and Zw (-4%). The values of H were two to three times higher than the quasistatic elastances estimated with greater volume changes (greater than 20 ml).

Rib cage vs. abdominal displacement in dogs during forced oscillation to 32 Hz

1989 ◽  
Vol 67 (4) ◽  
pp. 1472-1478 ◽  
Author(s):  
B. R. Boynton ◽  
G. Glass ◽  
I. D. Frantz ◽  
J. J. Fredberg
Keyword(s):  
Mechanical Behavior ◽  
Tidal Volume ◽  
Chest Wall ◽  
Forced Oscillation ◽  
Body Plethysmography ◽  
Volume Changes ◽  
Volume Increase ◽  
Rib Cage ◽  
Anesthetized Dogs ◽  
Inductive Plethysmography

Allen et al. (J. Clin. Invest. 76: 620–629, 1985) reported that during oscillatory forcing the base of isolated canine lungs distends preferentially relative to the apex as frequency and tidal volume increase. The tendency toward such nonuniform phasic lung distension might influence phasic displacement of the rib cage (RC) relative to the abdomen (ABD). To test this hypothesis we measured RC and ABD displacement in four anesthetized dogs during forced oscillation. Sinusoidal volume changes were delivered through a tracheostomy at 1–32 Hz and measured by body plethysmography. RC and ABD displacements were measured by inductive plethysmography. During oscillation with air at fixed tidal volumes (10–80 ml) RC, normalized to unity at 1 Hz, increased to 2.06–2.22 at 8 Hz (P less than 0.001) and then decreased to 1.06–1.35 (P less than 0.0025) at 32 Hz. ABD, normalized to unity at 1 Hz, was 1.12–1.16 at 4 Hz (P less than 0.001) and decreased to 0.12–0.14 at 32 Hz (P less than 0.001). Displacement of ABD relative to RC did not increase systematically with increasing tidal volume during sinusoidal forcing at any frequency. Thus we found no discernible influence of nonuniform phasic lung distension on chest wall behavior. We infer that in the dog the nonuniform mechanical behavior of the chest wall dominates the nonuniform (but opposing) mechanical tendency of the lung.

Total and local impedances of the chest wall up to 10 Hz

1990 ◽  
Vol 68 (4) ◽  
pp. 1409-1414 ◽  
Author(s):  
G. M. Barnas ◽  
K. Yoshino ◽  
J. Fredberg ◽  
Y. Kikuchi ◽  
S. H. Loring ◽  
...  
Keyword(s):  
Chest Wall ◽  
Healthy Subjects ◽  
Vital Capacity ◽  
Respiratory Muscles ◽  
Volume Changes ◽  
Impedance Measurements ◽  
Rib Cage ◽  
Gastric Pressure ◽  
Local Properties ◽  
Diameter Change

To understand how bical mechanical chest wall (CW) properties are related to those of the CW as a whole, we measured esophageal and gastric pressures, CW volume changes (measured with a head-out body plethysmograph), and anteroposterior and transverse CW diameter changes (measured with magnetometers attached to the surface) during sinusoidal forcing at the mouth (2.5% vital capacity, 0.5-10 Hz) in four healthy subjects. Total CW resistance decreased sharply as frequency rose to 3-4 Hz and remained relatively constant at higher frequencies. Total CW reactance became less negative with increasing frequency but showed no tendency to change sign. Above 2 Hz, diameters measured at different locations changed asynchronously between and within the rib cage and abdomen. “Local pathway impedances” (ratios of esophageal or gastric pressure to a rate of diameter change) showed frequency dependence similar to that of the total CW less than 3 Hz. Local pathway impedances increased during contraction of respiratory muscles acting on the pathway. We conclude that 1) total CW behavior is mainly a reflection of its individual local properties at less than or equal to 3 Hz, 2) local impedances within the rib cage or within the abdomen can change independently in some situations, and 3) asynchronies that develop within the CW during forcing greater than 3 Hz suggest that two compartments may be insufficient to describe CW properties from impedance measurements.

Dynamic behavior of excised dog rib cage: dependence on muscle

1991 ◽  
Vol 70 (3) ◽  
pp. 1059-1067 ◽  
Author(s):  
Y. Kikuchi ◽  
D. Stamenovic ◽  
S. H. Loring
Keyword(s):  
Dynamic Behavior ◽  
Chest Wall ◽  
Sagittal Plane ◽  
Respiratory Muscles ◽  
Midsagittal Plane ◽  
Low Frequencies ◽  
Rib Cage ◽  
Displacement Behavior ◽  
Force Displacement ◽  
Chest Wall Elastance

To assess the contribution of the rib cage to chest wall elastance and hysteresis, we measured force-displacement behavior of the isolated canine rib cage during sinusoidal forcing of the sternum in the midsagittal plane at low frequencies (0.02-2.0 Hz). Elastance of the rib cage was nearly invariant with frequency of forcing from 0.02 to 1.0 Hz and decreased with increasing amplitude. Hysteresis, the width of the force-displacement loop at middisplacement (zero displacement), was nearly constant with frequency below 1.0 Hz and increased with increasing amplitude of forcing. Removal of muscle reduced elastance and hysteresis of the rib cage substantially. The data suggest that the excised dog rib cage shows dynamic behavior similar to that of the intact human rib cage and chest wall and that respiratory muscle is responsible for a major part of the behavior of the passive chest wall. We also calculated the major and minor stiffnesses in the sagittal plane, which differed by a factor of 3-11, and their directions lay close to the dorsoventral and cephalocaudal axes, respectively. Removal of muscle reduced the stiffnesses but did not change their directions. Thus, although respiratory muscles impede motion in the sagittal plane, they do not alter its pattern.

Relative volume changes of the rib cage and abdomen during prephonatory chest wall posturing

1988 ◽  
Vol 2 (1) ◽  
pp. 13-19 ◽  
Author(s):  
Thomas J. Hixon ◽  
Peter J. Watson ◽  
Frances P. Harris ◽  
Nancy B. Pearl
Keyword(s):  
Chest Wall ◽  
Relative Volume ◽  
Volume Changes ◽  
Rib Cage

Effect of rib cage and abdominal restriction on total respiratory resistance and reactance

1986 ◽  
Vol 61 (5) ◽  
pp. 1736-1740 ◽  
Author(s):  
J. A. van Noord ◽  
M. Demedts ◽  
J. Clement ◽  
M. Cauberghs ◽  
K. P. Van de Woestijne
Keyword(s):  
Chest Wall ◽  
Respiratory Resistance ◽  
Low Frequencies ◽  
Rib Cage ◽  
Lung Capacity ◽  
Residual Capacity ◽  
The Subject ◽  
A Minor ◽  
Male Subjects ◽  
Airway Conductance

In 14 healthy male subjects we studied the effects of rib cage and abdominal strapping on lung volumes, airway resistance (Raw), and total respiratory resistance (Rrs) and reactance (Xrs). Rib cage, as well as abdominal, strapping caused a significant decrease in vital capacity (respectively, -36 and -34%), total lung capacity (TLC) (-31 and -27%), functional residual capacity (FRC) (-28 and -28%), and expiratory reserve volume (-40 and -48%) and an increase in specific airway conductance (+24 and +30%) and in maximal expiratory flow at 50% of control TLC (+47 and +42%). The decrease of residual volume (RV) was significant (-12%) with rib cage strapping only. Abdominal strapping resulted in a minor overall increase in Rrs, whereas rib cage strapping produced a more marked increase at low frequencies; thus a frequency dependence of Rrs was induced. A similar pattern, but with lower absolute values, of Rrs was obtained by thoracic strapping when the subject was breathing at control FRC. Xrs was decreased, especially at low frequencies, with abdominal strapping and even more with thoracic strapping; thus the resonant frequency of the respiratory system was shifted toward higher frequencies. Partitioning Rrs and Xrs into resistance and reactance of lungs and chest wall demonstrated that the different effects of chest wall and abdominal strapping on Rrs and Xrs reflect changes mainly of chest wall mechanics.

scholarly journals Effects of PEEP and tidal volume on elastances and distribution of volume changes of the different chest wall compartments

Critical Care ◽  
10.1186/cc841 ◽  
2000 ◽  
Vol 4 (Suppl 1) ◽  
pp. P121
Author(s):  
A Aliverti ◽  
R Dellacà ◽  
A Lo Mauro ◽  
E Carlesso ◽  
W Del Frate ◽  
...  
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Volume Changes

COMPARTMENTAL VOLUME CHANGES AND CHEST WALL MECHANICS AFTER EPIDURAL FENTANYL

1986 ◽  
Vol 65 (Supplement 3A) ◽  
pp. A498 ◽  
Author(s):  
B. Mankikian ◽  
J. F. Brichant ◽  
B. Riou ◽  
M. A. Delima ◽  
R. Sartene ◽  
...  
Keyword(s):  
Chest Wall ◽  
Epidural Fentanyl ◽  
Volume Changes ◽  
Chest Wall Mechanics

Three degree of freedom description of movement of the human chest wall

1986 ◽  
Vol 60 (3) ◽  
pp. 928-934 ◽  
Author(s):  
J. C. Smith ◽  
J. Mead
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Pubic Symphysis ◽  
Degree Of Freedom ◽  
Rib Cage ◽  
Additional Degree ◽  
Wall Movement ◽  
Surface Displacements ◽  
Flexion Extension ◽  
Three Degree Of Freedom

A three degree of freedom description of movement of the human chest wall is presented. In addition to the standard variables representing surface displacements of the rib cage and abdominal wall in transverse planes, the description includes a variable representing axial displacements of the chest wall associated with postural movements of the spine and pelvis. A simple technique was developed for quantifying the axial displacements using a single measurement by magnetometry of changes in the distance between a point on the anterior surface of the rib cage near the xiphisternum and a point on the abdominal surface near the pubic symphysis. It was found that axial displacements produced by either flexion-extension of the spine or rotation of the pelvis in the standing postures can be treated as a single degree of freedom. The chest wall displacements induced over the range of axial displacement examined were as large as those normally accompanying a change in lung volume on the order of 30–50% of the vital capacity. It is concluded, however, that although this additional degree of freedom can cause large chest wall displacements, it probably cannot independently change lung volume. This implies that the system is constrained so that there are only a limited number of independent modes of chest wall movement that are capable of producing significant changes in lung volume. It also suggests that the system is constructed so that lung volume can be relatively independent of certain postural distortions of the chest wall.

Regional coupling between chest wall and lung expansion during HFV: a positron imaging study

1993 ◽  
Vol 74 (5) ◽  
pp. 2242-2252 ◽  
Author(s):  
J. G. Venegas ◽  
K. Tsuzaki ◽  
B. J. Fox ◽  
B. A. Simon ◽  
C. A. Hales
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Gas Transport ◽  
Regional Scale ◽  
Regional Distribution ◽  
Imaging Study ◽  
High Frequency Ventilation ◽  
Rib Cage ◽  
Lung Expansion ◽  
Frequency Ventilation

Apparently conflicting differences between the regional chest wall motion and gas transport have been observed during high-frequency ventilation (HFV). To elucidate the mechanism responsible for such differences, a positron imaging technique capable of assessing dynamic chest wall volumetric expansion, regional lung volume, and regional gas transport was developed. Anesthetized supine dogs were studied at ventilatory frequencies (f) ranging from 1 to 15 Hz and eucapnic tidal volumes. The regional distribution of mean lung volume was found to be independent of f, but the apex-to-base ratio of regional chest wall expansion favored the lung bases at low f and became more homogeneous at higher f. Regional gas transport per unit of lung volume, assessed from washout maneuvers, was homogeneous at 1 Hz, favored the bases progressively as f increased to 9 Hz, and returned to homogeneity at 15 Hz. Interregional asynchrony (pendelluft) and right-to-left differences were small at this large regional scale. Analysis of the data at a higher spatial resolution showed that the motion of the diaphragm relative to the excursions of the rib cage decreased as f increased. These differences from apex to base in regional chest wall expansion and gas transport were consistent with a simple model including lung, rib cage, and diaphragm regional impedances and a viscous coupling between lungs and chest wall caused by the relative sliding between pleural surfaces. To further test this model, we studied five additional animals under open chest conditions. These studies resulted in a homogeneous and f-independent regional gas transport. We conclude that the apex-to-base distribution of gas transport observed during HFV is not caused by intrinsic lung heterogeneity but rather is a result of chest wall expansion dynamics and its coupling to the lung.

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