Chest wall mechanics during artificial ventilation

1975 ◽  
Vol 38 (4) ◽  
pp. 576-580 ◽  
Author(s):  
G. Grimby ◽  
G. Hedenstierna ◽  
B. Lofstrom
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Gas Flow ◽  
Artificial Ventilation ◽  
Conscious State ◽  
Rib Cage ◽  
Chest Wall Mechanics ◽  
Pressure Volume Relationship ◽  
Relationship Of ◽  
Gas Volume

Chest wall mechanics were studied in six healthy volunteers before and during anesthesia prior to surgery. The intratracheal, esophageal, and intragastric pressures were measured concurrently. Gas flow was measured by pneumotachography and gas volume was obtained from it by electrical integration. Rib cage and abdomen movements were registered with magnetometers, these being calibrated by “isovolume” maneuvers. During spontaneous breathing in the conscious state, rib cage volume displacement corresponded to 40% of the tidal volume. During anesthesia and artificial ventilation, this rose to 72% of the tidal volume. The relative contributions of rib cage and abdomen displacements were not influenced by a change in tidal volume. Compliance was higher with a larger tidal volume, a finding which could be due to a curved pressure-volume relationship of the overall chest wall.

Changes in chest wall structure and elasticity in elastase-induced emphysema

1986 ◽  
Vol 61 (5) ◽  
pp. 1821-1829 ◽  
Author(s):  
A. J. Thomas ◽  
G. S. Supinski ◽  
S. G. Kelsen
Keyword(s):  
Chest Wall ◽  
Spinal Column ◽  
Wall Structure ◽  
Rib Cage ◽  
Thoracic Spinal ◽  
Volume Curve ◽  
Volume Relationship ◽  
Pressure Volume Relationship ◽  
Relationship Of ◽  
Anterior Posterior

The present study examined the effects of elastase-induced emphysema on the structure and elasticity of the chest wall. Specifically, we examined the passive pressure-volume relationship of the intact chest wall in anesthetized animals and the stress-strain relationship of the isolated rib cage devoid of respiratory musculature. The structure of the isolated rib cage was assessed by measuring its circumferential, anterior-posterior, and transverse dimensions, the angles of articulation of the ribs at the costovertebral and sternochondral joints, and the length of the sternum and individual ribs. Studies were performed in 10 Syrian Golden hamsters, 26–27 wk after intratracheal injection of elastase, and 9 saline-injected hamsters that served as controls. Mean functional residual capacity of emphysematous animals was 239% of the value obtained in control animals. In emphysematous animals, the pressure-volume curve of the chest wall was shifted parallel and to the left of the curve obtained in controls. That is, at any given esophageal pressure, lung volume was significantly greater in emphysematous animals compared with controls, but the slope of the pressure-volume relationship was similar in the two groups. In the relaxed position, the circumference, anterior-posterior, transverse, and rostral-caudal dimensions of the thorax were significantly greater in emphysematous than control animals. Although the length of the thoracic spinal column was the same in both groups, the length of the ribs and sternum were greater in emphysematous animals and the angles of articulation of the ribs with the vertebrae and sternum were altered.(ABSTRACT TRUNCATED AT 250 WORDS)

Chest wall mechanics in sustained microgravity

1998 ◽  
Vol 84 (6) ◽  
pp. 2060-2065 ◽  
Author(s):  
Muriel Wantier ◽  
Marc Estenne ◽  
Sylvia Verbanck ◽  
G. Kim Prisk ◽  
Manuel Paiva
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Functional Residual Capacity ◽  
Postural Change ◽  
Rib Cage ◽  
Chest Wall Mechanics ◽  
Supine Posture ◽  
Abdominal Compliance ◽  
Residual Capacity ◽  
Measured Flow

We assessed the effects of sustained weightlessness on chest wall mechanics in five astronauts who were studied before, during, and after the 10-day Spacelab D-2 mission ( n = 3) and the 180-day Euromir-95 mission ( n= 2). We measured flow and pressure at the mouth and rib cage and abdominal volumes during resting breathing and during a relaxation maneuver from midinspiratory capacity to functional residual capacity. Microgravity produced marked and consistent changes (Δ) in the contribution of the abdomen to tidal volume [ΔVab/(ΔVab + ΔVrc), where Vab is abdominal volume and Vrc is rib cage volume], which increased from 30.7 ± 3.5 (SE)% at 1 G head-to-foot acceleration to 58.3 ± 5.7% at 0 G head-to-foot acceleration ( P < 0.005). Values of ΔVab/(ΔVab + ΔVrc) did not change significantly during the 180 days of the Euromir mission, but in the two subjects ΔVab/(ΔVab + ΔVrc) was greater on postflight day 1 than on subsequent postflight days or preflight. In the two subjects who produced satisfactory relaxation maneuvers, the slope of the Konno-Mead plot decreased in microgravity; this decrease was entirely accounted for by an increase in abdominal compliance because rib cage compliance did not change. These alterations are similar to those previously reported during short periods of weightlessness inside aircrafts flying parabolic trajectories. They are also qualitatively similar to those observed on going from upright to supine posture; however, in contrast to microgravity, such postural change reduces rib cage compliance.

Pulmonary mechanics during rapid mechanical ventilation in rabbits with saline-lavaged lungs

1986 ◽  
Vol 61 (4) ◽  
pp. 1431-1437 ◽  
Author(s):  
J. J. Perez Fontan ◽  
B. S. Turner ◽  
G. P. Heldt ◽  
G. A. Gregory
Keyword(s):  
Tidal Volume ◽  
Gas Flow ◽  
Transpulmonary Pressure ◽  
Inspiratory Flow ◽  
Pulmonary Mechanics ◽  
Mechanically Ventilated ◽  
Ventilatory Rate ◽  
Residual Capacity ◽  
Pressure Volume Relationship ◽  
Linear Ramp

Infants with respiratory failure are frequently mechanically ventilated at rates exceeding 60 breaths/min. We analyzed the effect of ventilatory rates of 30, 60, and 90 breaths/min (inspiratory times of 0.6, 0.3, and 0.2 s, respectively) on the pressure-flow relationships of the lungs of anesthetized paralyzed rabbits after saline lavage. Tidal volume and functional residual capacity were maintained constant. We computed effective inspiratory and expiratory resistance and compliance of the lungs by dividing changes in transpulmonary pressure into resistive and elastic components with a multiple linear regression. We found that mean pulmonary resistance was lower at higher ventilatory rates, while pulmonary compliance was independent of ventilatory rate. The transpulmonary pressure developed by the ventilator during inspiration approximated a linear ramp. Gas flow became constant and the pressure-volume relationship linear during the last portion of inspiration. Even at a ventilatory rate of 90 breaths/min, 28–56% of the tidal volume was delivered with a constant inspiratory flow. Our findings are consistent with the model of Bates et al. (J. Appl. Physiol. 58: 1840–1848, 1985), wherein the distribution of gas flow within the lungs depends predominantly on resistive factors while inspiratory flow is increasing, and on elastic factors while inspiratory flow is constant. This dynamic behavior of the surfactant-depleted lungs suggests that, even with very short inspiratory times, distribution of gas flow within the lungs is in large part determined by elastic factors. Unless the inspiratory time is further shortened, gas flow may be directed to areas of increased resistance, resulting in hyperinflation and barotrauma.

CHEST WALL MECHANICS DURING ARTIFICIAL VENTILATION

1976 ◽  
Vol 20 (4) ◽  
pp. 292 ◽  
Author(s):  
G. GRIMBY ◽  
G. HEDENSTIERNA ◽  
B. L??FSTR??M
Keyword(s):  
Chest Wall ◽  
Artificial Ventilation ◽  
Chest Wall Mechanics

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.

Respiratory cross-sectional area-flux measurements of the human chest wall

1990 ◽  
Vol 68 (4) ◽  
pp. 1605-1614 ◽  
Author(s):  
R. Sartene ◽  
P. Martinot-Lagarde ◽  
M. Mathieu ◽  
A. Vincent ◽  
M. Goldman ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Tidal Volume ◽  
Chest Wall ◽  
Normal Subjects ◽  
Cross Sectional Area ◽  
7 Tesla ◽  
Sectional Area ◽  
Cross Sectional ◽  
Rib Cage ◽  
Orientation Effects

A new device that utilizes the voltages induced in separate coils encircling the rib cage and abdomen by a magnetic field is described for measurement of cross-sectional areas of the human chest wall (rib cage and abdomen) and their variation during breathing. A uniform magnetic field (1.4 X 10(-7) Tesla at 100 kHz) is produced by generating an alternating current at 100 kHz in two square coils, 1.98 m on each side, parallel to the planes of the areas to be measured and placed symmetrically cephalad and caudad to these planes at a mean distance of 0.53 m. We demonstrated that the accuracy of the device on well-defined surfaces (squares, circles, rectangles, ellipses) was within 1% in all cases. Observed errors are due primarily to small inhomogeneities of the magnetic field and variation of the orientation of the coil relative to the field. Using a second magnetic field (80 kHz) perpendicular to the first, we measured the errors due to nonparallel orientation during quiet breathing and inspiratory capacity maneuvers. In 10 normal subjects, orientation effects were less than 2% for the rib cage and less than 0.7% for the abdomen. In five of these subjects, orientation effects at functional residual capacity in lateral and seated postures were generally less than or equal to 5%, but estimated tidal volume during spontaneous breathing was comparable to measurements in the supine posture. In five curarized patients, we assessed the linearity of volume-motion relationships of the rib cage and abdomen, comparing cross-sectional area and circumference measurements. Departures from linearity using cross-sectional areas were only one-third of those using circumferences. In seven normal subjects we compared cross-sectional area measurements with respiratory inductive plethysmography (RIP) and found comparable estimates of lung volume change over a wide range of relative rib cage contributions to tidal volume (-5 to 105%), with slightly higher standard deviations for the RIP (SD = 10% for RIP; SD = 4% for cross-sectional area).

The influence of supine posture on chest wall volume changes is higher in obese than in normal weight children

2015 ◽  
Vol 40 (2) ◽  
pp. 178-183
Author(s):  
Letícia Silva ◽  
Jacqueline de Melo Barcelar ◽  
Catarina Souza Rattes ◽  
Larissa Bouwman Sayão ◽  
Cyda Albuquerque Reinaux ◽  
...  
Keyword(s):  
Pulmonary Function ◽  
Tidal Volume ◽  
Chest Wall ◽  
Supine Position ◽  
Normal Weight ◽  
Obese Children ◽  
Rib Cage ◽  
Percentage Contribution ◽  
Supine Posture ◽  
And Control

The objective of this study was to analyze thoraco-abdominal kinematics in obese children in seated and supine positions during spontaneous quiet breathing. An observational study of pulmonary function and chest wall volume assessed by optoelectronic plethysmography was conducted on 35 children aged 8–12 years that were divided into 2 groups according to weight/height ratio percentiles: there were 18 obese children with percentiles greater than 95 and 17 normal weight children with percentiles of 5–85. Pulmonary function (forced expiratory volume in 1 s (FEV1); forced vital capacity (FVC); and FEV1/FVC ratio), ventilatory pattern, total and compartment chest wall volume variations, and thoraco-abdominal asynchronies were evaluated. Tidal volume was greater in seated position. Pulmonary and abdominal rib cage tidal volume and their percentage contribution to tidal volume were smaller in supine position in both obese and control children, while abdominal tidal volume and its percentage contribution was greater in the supine position only in obese children and not in controls. No statistically significant differences were found between obese and control children and between supine and seated positions regarding thoraco-abdominal asynchronies. We conclude that in obese children thoraco-abdominal kinematics is influenced by supine posture, with an increase of the abdominal and a decreased rib cage contribution to ventilation, suggesting that in this posture areas of hypoventilation can occur in the lung.

Association of chest wall motion and tidal volume responses during CO2 rebreathing

1996 ◽  
Vol 81 (4) ◽  
pp. 1528-1534 ◽  
Author(s):  
Sheng Yan ◽  
Pawel Sliwinski ◽  
Peter T. Macklem
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Wall Motion ◽  
Forced Expiratory Volume ◽  
Quiet Breathing ◽  
Rib Cage ◽  
Chest Wall Motion ◽  
Variable Recruitment ◽  
The Individual ◽  
End Tidal

Yan, Sheng, Pawel Sliwinski, and Peter T. Macklem.Association of chest wall motion and tidal volume responses during CO2 rebreathing. J. Appl. Physiol. 81(4): 1528–1534, 1996.—The purpose of this study is to investigate the effect of chest wall configuration at end expiration on tidal volume (Vt) response during CO2 rebreathing. In a group of 11 healthy male subjects, the changes in end-expiratory and end-inspiratory volume of the rib cage (ΔVrc,e and ΔVrc,i, respectively) and abdomen (ΔVab,eand ΔVab,i, respectively) measured by linearized magnetometers were expressed as a function of end-tidal[Formula: see text]([Formula: see text]). The changes in end-expiratory and end-inspiratory volumes of the chest wall (ΔVcw,e and ΔVcw,i, respectively) were calculated as the sum of the respective rib cage and abdominal volumes. The magnetometer coils were placed at the level of the nipples and 1–2 cm above the umbilicus and calibrated during quiet breathing against the Vt measured from a pneumotachograph. The ΔVrc,e/[Formula: see text]slope was quite variable among subjects. It was significantly positive ( P < 0.05) in five subjects, significantly negative in four subjects ( P < 0.05), and not different from zero in the remaining two subjects. The ΔVab,e/[Formula: see text]slope was significantly negative in all subjects ( P < 0.05) with a much smaller intersubject variation, probably suggesting a relatively more uniform recruitment of abdominal expiratory muscles and a variable recruitment of rib cage muscles during CO2rebreathing in different subjects. As a group, the mean ΔVrc,e/[Formula: see text], ΔVab,e/[Formula: see text], and ΔVcw,e/[Formula: see text]slopes were 0.010 ± 0.034, −0.030 ± 0.007, and −0.020 ± 0.032 l / Torr, respectively; only the ΔVab,e/[Formula: see text]slope was significantly different from zero. More interestingly, the individual ΔVt/[Formula: see text]slope was negatively associated with the ΔVrc,e/[Formula: see text]( r = −0.68, P = 0.021) and ΔVcw,e/[Formula: see text]slopes ( r = −0.63, P = 0.037) but was not associated with the ΔVab,e/[Formula: see text]slope ( r = 0.40, P = 0.223). There was no correlation of the ΔVrc,e/[Formula: see text]and ΔVcw,e/[Formula: see text]slopes with age, body size, forced expiratory volume in 1 s, or expiratory time. The group ΔVab,i/[Formula: see text]slope (0.004 ± 0.014 l / Torr) was not significantly different from zero despite the Vt nearly being tripled at the end of CO2 rebreathing. In conclusion, the individual Vtresponse to CO2, although independent of ΔVab,e, is a function of ΔVrc,e to the extent that as the ΔVrc,e/[Formula: see text]slope increases (more positive) among subjects, the Vt response to CO2 decreases. These results may be explained on the basis of the respiratory muscle actions and interactions on the rib cage.

Effects of lung volume on lung and chest wall mechanics in rats

1999 ◽  
Vol 86 (1) ◽  
pp. 16-21 ◽  
Author(s):  
T. Hirai ◽  
K. A. McKeown ◽  
R. F. M. Gomes ◽  
J. H. T. Bates
Keyword(s):  
Chest Wall ◽  
Respiratory System ◽  
Lung Volume ◽  
Small Animal ◽  
Tissue Mechanics ◽  
Lung Mechanics ◽  
Open Chest ◽  
Pressure Volume Relationship ◽  
Volume Resistance ◽  
Relationship Of

To investigate the effect of lung volume on chest wall and lung mechanics in the rats, we measured the impedance (Z) under closed- and open-chest conditions at various positive end-expiratory pressures (0–0.9 kPa) by using a computer-controlled small-animal ventilator (T. F. Schuessler and J. H. T. Bates. IEEE Trans. Biomed. Eng. 42: 860–866, 1995) that we have developed for determining accurately the respiratory Z in small animals. The Z of total respiratory system and lungs was measured with small-volume oscillations between 0.25 and 9.125 Hz. The measured Z was fitted to a model that featured a constant-phase tissue compartment (with dissipation and elastance characterized by constants G and H, respectively) and a constant airway resistance (Z. Hantos, B. Daroczy, B. Suki, S. Nagy, and J. J. Fredberg. J. Appl. Physiol. 72: 168–178, 1992). We matched the lung volume between the closed- and open-chest conditions by using the quasi-static pressure-volume relationship of the lungs to calculate Z as a function of lung volume. Resistance decreased with lung volume and was not significantly different between total respiratory system and lungs. However, G and H of the respiratory system were significantly higher than those of the lungs. We conclude that chest wall in rats has a significant influence on tissue mechanics of the total respiratory system.

Effects of acute hyperinflation on chest wall mechanics in dogs

1987 ◽  
Vol 63 (4) ◽  
pp. 1493-1498 ◽  
Author(s):  
M. Decramer ◽  
T. X. Jiang ◽  
M. Demedts
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Total Lung Capacity ◽  
Emg Activity ◽  
Sectional Area ◽  
Cross Sectional ◽  
Lung Capacity ◽  
Chest Wall Mechanics ◽  
Gastric Pressure ◽  
Residual Capacity

We studied chest wall mechanics at functional residual capacity (FRC) and near total lung capacity (TLC) in 14 supine anesthetized and vagotomized dogs. During breathing near TLC compared with FRC, tidal volume decreased (674 +/- 542 vs. 68 +/- 83 ml; P less than 0.025). Both inspiratory changes in gastric pressure (4.5 +/- 2.5 vs. -0.2 +/- 2.0 cmH2O; P less than 0.005) and changes in abdominal cross-sectional area (25 +/- 17 vs. -1.0 +/- 4.2%; P less than 0.001) markedly decreased; they were both often negative during inspiration near TLC. Parasternal intercostal shortening decreased (-3.0 +/- 3.7 vs. -2.0 +/- 2.7%), whereas diaphragmatic shortening decreased slightly more in both costal and crural parts (costal -8.4 +/- 2.9 vs. -4.3 +/- 4.1%, crural -22.8 +/- 13.2 vs. -10.0 +/- 7.5%; P less than 0.05). As a result, the ratio of parasternal to diaphragm shortening increased near TLC (0.176 +/- 0.135 vs. 0.396 +/- 0.340; P less than 0.05). Electromyographic (EMG) activity in the parasternals slightly decreased near TLC, whereas the EMG activity in the costal and crural parts of the diaphragm slightly increased. We conclude that 1) the mechanical outcome of diaphragmatic contraction near TLC is markedly reduced, and 2) the mechanical outcome of parasternal intercostal contraction near TLC is clearly less affected.

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