Effects of increased +Gz on chest wall mechanics in humans

1995 ◽  
Vol 78 (3) ◽  
pp. 997-1003 ◽  
Author(s):  
M. Estenne ◽  
A. Van Muylem ◽  
W. Kinnear ◽  
M. Gorini ◽  
V. Ninane ◽  
...  
Keyword(s):  
Chest Wall ◽  
Minute Ventilation ◽  
Normal Subjects ◽  
Abdominal Pressure ◽  
Transdiaphragmatic Pressure ◽  
Parabolic Flights ◽  
Linear Effect ◽  
Chest Wall Mechanics ◽  
Abdominal Compliance ◽  
Tidal Changes

We studied the effects of head-to-foot acceleration (+Gz) on chest wall mechanics in five normal subjects seated in a human centrifuge. Results were compared with those previously obtained in the same subjects in microgravity during parabolic flights. In all subjects, end-expiratory abdominal pressure (Pga) and volume (Vab) increased with Gz. On average, end-expiratory Pga increased from 7.4 +/- 1.7 cmH2O at + 1 Gz to 14.9 +/- 2.8 cmH2O at + 3 Gz and end-expiratory Vab increased by 0.32 +/- 0.06 liter between + 1 and + 3 Gz. On the other hand, the abdominal contribution to tidal volume (Vab/VT) and abdominal compliance decreased from 34.7 +/- 5.9% and 52 +/- 6 ml/cmH2O at + 1 Gz to 29.3 +/- 5.1% and 26 +/- 4 ml/cmH2O at + 3 Gz, respectively. Changes in end-expiratory Pga were linear between 0 and + 3 Gz, but changes in end-expiratory Vab, Vab/VT, and abdominal compliance were greater in microgravity than in hypergravity. In contrast to weightlessness, which did not alter minute ventilation and tidal changes in Pga and transdiaphragmatic pressure, these variables increased with increasing Gz. These results indicate that, although changes in Gz have a linear effect on abdominal transmural pressure, hypergravity and weightlessness do not have symmetrical effects on chest wall mechanics.

Lung and chest wall mechanics in microgravity

1991 ◽  
Vol 71 (5) ◽  
pp. 1956-1966 ◽  
Author(s):  
J. Edyvean ◽  
M. Estenne ◽  
M. Paiva ◽  
L. A. Engel
Keyword(s):  
Chest Wall ◽  
Dynamic Compliance ◽  
Normal Subjects ◽  
Abdominal Pressure ◽  
Transdiaphragmatic Pressure ◽  
Gastric Pressure ◽  
Abdominal Compliance ◽  
Consistent Change ◽  
Residual Capacity ◽  
Measured Flow

We studied the effect of 15–20 s of weightlessness on lung, chest wall, and abdominal mechanics in five normal subjects inside an aircraft flying repeated parabolic trajectories. We measured flow at the mouth, thoracoabdominal and compartmental volume changes, and gastric pressure (Pga). In two subjects, esophageal pressures were measured as well, allowing for estimates of transdiaphragmatic pressure (Pdi). In all subjects functional residual capacity at 0 Gz decreased by 244 +/- 31 ml as a result of the inward displacement of the abdomen. End-expiratory Pga decreased from 6.8 +/- 0.8 cmH2O at 1 Gz to 2.5 +/- 0.3 cmH2O at Gz (P less than 0.005). Abdominal contribution to tidal volume increased from 0.33 +/- 0.05 to 0.51 +/- 0.04 at 0 Gz (P less than 0.001) but delta Pga showed no consistent change. Hence abdominal compliance increased from 43 +/- 9 to 70 +/- 10 ml/cmH2O (P less than 0.05). There was no consistent effect of Gz on tidal swings of Pdi, on pulmonary resistance and dynamic compliance, or on any of the timing parameters determining the temporal pattern of breathing. The results indicate that at 0 G respiratory mechanics are intermediate between those in the upright and supine postures at 1 G. In addition, analysis of end-expiratory pressures suggests that during weightlessness intra-abdominal pressure is zero, the diaphragm is passively tensed, and a residual small pleural pressure gradient may be present.

Effects of separate rib cage and abdominal restriction on exercise performance in normal humans

1985 ◽  
Vol 58 (6) ◽  
pp. 2020-2026 ◽  
Author(s):  
S. N. Hussain ◽  
B. Rabinovitch ◽  
P. T. Macklem ◽  
R. L. Pardy
Keyword(s):  
Minute Ventilation ◽  
Normal Subjects ◽  
Cycle Ergometer ◽  
Abdominal Muscle ◽  
Work Rate ◽  
Abdominal Pressure ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Constant Work Rate ◽  
And Control

We assessed the effects of selective restriction of movements of the rib cage (Res,rc) and abdomen (Res,ab) on ventilatory pattern, transdiaphragmatic pressure (Pdi), and electrical activity of the diaphragm (Edi) in five normal subjects exercising at a constant work rate (80% of maximum power output) on a cycle ergometer till exhaustion. Restriction of movements was achieved by an inelastic corset applied tightly around the rib cage or abdomen. Edi was recorded by an esophageal electrode, rectified, and then integrated, and peak values during inspiration were measured. Each subject exercised at the same work rate on 3 days: with Res,rc, with Res,ab, and without restriction (control). Res,rc but not Res,ab reduced exercise time (tlim). Up to tlim, minute ventilation (VE) was similar in all three conditions. At any level of VE, however, Res,rc decreased tidal volume and inspiratory and expiratory time, whereas Res,ab had no effect on the pattern of breathing. Res,ab was associated with higher inspiratory Pdi swings at any level of VE, whereas peak Edi was similar to control. Inspiratory Pdi swings were the same with Res,rc as control, but the peak Edi for a given Pdi was greater with Res,rc (P less than 0.05). During Res,rc the abdominal pressure swings in expiration were greater than with Res,ab and control. We conclude that Res,rc altered the pattern of breathing in normal subjects in high-intensity exercise, decreased diaphragmatic contractility, increased abdominal muscle recruitment in expiration, and reduced tlim. On the other hand, Res,ab had no effect on breathing pattern or tlim but was associated with increased diaphragmatic contractility.

scholarly journals Respiratory dynamics during laughter

2001 ◽  
Vol 90 (4) ◽  
pp. 1441-1446 ◽  
Author(s):  
Mario Filippelli ◽  
Riccardo Pellegrino ◽  
Iacopo Iandelli ◽  
Gianni Misuri ◽  
Joseph R. Rodarte ◽  
...  
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Dynamic Compression ◽  
Three Dimensional ◽  
Normal Subjects ◽  
Average Frequency ◽  
Abdominal Pressure ◽  
Sudden Increase ◽  
Lung Volumes ◽  
Transdiaphragmatic Pressure

Lung and chest wall mechanics were studied during fits of laughter in 11 normal subjects. Laughing was naturally induced by showing clips of the funniest scenes from a movie by Roberto Benigni. Chest wall volume was measured by using a three-dimensional optoelectronic plethysmography and was partitioned into upper thorax, lower thorax, and abdominal compartments. Esophageal (Pes) and gastric (Pga) pressures were measured in seven subjects. All fits of laughter were characterized by a sudden occurrence of repetitive expiratory efforts at an average frequency of 4.6 ± 1.1 Hz, which led to a final drop in functional residual capacity (FRC) by 1.55 ± 0.40 liter ( P < 0.001). All compartments similarly contributed to the decrease of lung volumes. The average duration of the fits of laughter was 3.7 ± 2.2 s. Most of the events were associated with sudden increase in Pes well beyond the critical pressure necessary to generate maximum expiratory flow at a given lung volume. Pga increased more than Pes at the end of the expiratory efforts by an average of 27 ± 7 cmH2O. Transdiaphragmatic pressure (Pdi) at FRC and at 10% and 20% control forced vital capacity below FRC was significantly higher than Pdi at the same absolute lung volumes during a relaxed maneuver at rest ( P < 0.001). We conclude that fits of laughter consistently lead to sudden and substantial decrease in lung volume in all respiratory compartments and remarkable dynamic compression of the airways. Further mechanical stress would have applied to all the organs located in the thoracic cavity if the diaphragm had not actively prevented part of the increase in abdominal pressure from being transmitted to the chest wall cavity.

The Effects of Increased Abdominal Pressure on Lung and Chest Wall Mechanics During Laparoscopic Surgery

1995 ◽  
Vol 81 (4) ◽  
pp. 744-750 ◽  
Author(s):  
Brenda G. Fahy ◽  
George M. Barnas ◽  
John L. Flowers ◽  
Sheryl E. Nagle ◽  
Mary J. Njoku
Keyword(s):  
Laparoscopic Surgery ◽  
Chest Wall ◽  
Abdominal Pressure ◽  
Chest Wall Mechanics

Effect of gravity on chest wall mechanics

2002 ◽  
Vol 92 (2) ◽  
pp. 709-716 ◽  
Author(s):  
D. Bettinelli ◽  
C. Kays ◽  
O. Bailliart ◽  
A. Capderou ◽  
P. Techoueyres ◽  
...  
Keyword(s):  
Linear System ◽  
Chest Wall ◽  
Lung Volume ◽  
Vital Capacity ◽  
Pressure Curve ◽  
Parabolic Flights ◽  
Chest Wall Mechanics ◽  
Exponential Decrease ◽  
Volume Range

Chest wall mechanics was studied in four subjects on changing gravity in the craniocaudal direction (Gz) during parabolic flights. The thorax appears very compliant at 0 Gz: its recoil changes only from −2 to 2 cmH2O in the volume range of 30–70% vital capacity (VC). Increasing Gz from 0 to 1 and 1.8 Gzprogressively shifted the volume-pressure curve of the chest wall to the left and also caused a fivefold exponential decrease in compliance. For lung volume <30% VC, gravity has an inspiratory effect, but this effect is much larger going from 0 to 1 Gz than from 1 to 1.8 Gz. For a volume from 30 to 70% VC, the effect is inspiratory going from 0 to 1 Gz but expiratory from 1 to 1.8 Gz. For a volume greater than ∼70% VC, gravity always has an expiratory effect. The data suggest that the chest wall does not behave as a linear system when exposed to changing gravity, as the effect depends on both chest wall volume and magnitude of Gz.

Rib cage mechanics during quiet breathing and exercise in humans

1997 ◽  
Vol 83 (4) ◽  
pp. 1242-1255 ◽  
Author(s):  
C. M. Kenyon ◽  
S. J. Cala ◽  
S. Yan ◽  
A. Aliverti ◽  
G. Scano ◽  
...  
Keyword(s):  
Chest Wall ◽  
Respiratory Muscles ◽  
Relaxation Curve ◽  
Abdominal Pressure ◽  
Abdominal Muscles ◽  
Quiet Breathing ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Ergometer Exercise ◽  
Exercise In Humans

Kenyon, C. M., S. J. Cala, S. Yan, A. Aliverti, G. Scano, R. Duranti, A. Pedotti, and Peter T. Macklem. Rib cage mechanics during quiet breathing and exercise in humans. J. Appl. Physiol. 83(4): 1242–1255, 1997.—During exercise, large pleural, abdominal, and transdiaphragmatic pressure swings might produce substantial rib cage (RC) distortions. We used a three-compartment chest wall model ( J. Appl. Physiol. 72: 1338–1347, 1992) to measure distortions of lung- and diaphragm-apposed RC compartments (RCp and RCa) along with pleural and abdominal pressures in five normal men. RCp and RCa volumes were calculated from three-dimensional locations of 86 markers on the chest wall, and the undistorted (relaxation) RC configuration was measured. Compliances of RCp and RCa measured during phrenic stimulation against a closed airway were 20 and 0%, respectively, of their values during relaxation. There was marked RC distortion. Thus nonuniform distribution of pressures distorts the RC and markedly stiffens it. However, during steady-state ergometer exercise at 0, 30, 50, and 70% of maximum workload, RC distortions were small because of a coordinated action of respiratory muscles, so that net pressures acting on RCp and RCa were nearly the same throughout the respiratory cycle. This maximizes RC compliance and minimizes the work of RC displacement. During quiet breathing, plots of RCa volume vs. abdominal pressure were to the right of the relaxation curve, indicating an expiratory action on RCa. We attribute this to passive stretching of abdominal muscles, which more than counterbalances the insertional component of transdiaphragmatic pressure.

The Effects of Increased Abdominal Pressure on Lung and Chest Wall Mechanics During Laparoscopic Surgery

1995 ◽  
Vol 81 (4) ◽  
pp. 744-750
Author(s):  
Brenda G. Fahy ◽  
George M. Barnas ◽  
John L. Flowers ◽  
Sheryl E. Nagle ◽  
Mary J. Njoku
Keyword(s):  
Laparoscopic Surgery ◽  
Chest Wall ◽  
Abdominal Pressure ◽  
Chest Wall Mechanics

Ventilatory saving by external chest wall compression or oral high-frequency oscillation in normal subjects and those with chronic airflow obstruction

1985 ◽  
Vol 69 (3) ◽  
pp. 349-359 ◽  
Author(s):  
R. J. D. George ◽  
R. J. D. Winter ◽  
S. J. Flockton ◽  
D. M. Geddes
Keyword(s):  
Chest Wall ◽  
High Frequency ◽  
Minute Ventilation ◽  
Airflow Obstruction ◽  
Normal Subjects ◽  
High Frequency Oscillation ◽  
Tidal Breathing ◽  
Frequency Oscillation ◽  
Resonant Frequencies ◽  
High Frequency Oscillations

1. Oscillation of the air within the lungs at high frequency is associated with an increased clearance of CO2. Because of the high frequency and low volume of these oscillations, spontaneous breathing is unhindered and the technique has potential value as a supplement to ventilation. 2. High-frequency oscillations were superimposed upon tidal breathing by using a loudspeaker attached to a mouthpiece (oral high-frequency oscillation, OHFO) or by external chest wall compression (ECWC). We set out (a) to compare the changes in ventilation and breathlessness by using OHFO and ECWC in normal subjects with those in patients with chronic airflow obstruction (CAO), and (b) to relate the pattern of saving to the resonant frequencies of the respiratory system as a whole (fOT, 5–10 Hz in normal subjects, 16–26 Hz in CAO) and those of the ribcage(foc,70 Hz). 3. OHFO reduced minute ventilation (VE) by up to 46% in normal subjects (P < 0.01) and 29% in CAO (P < 0.01) without any rise in CO2. ECWC reduced VE by 27% in normal subjects (P < 0.01) and 16% in CAO (P < 0.01) without a rise in CO2. 4. High-frequency oscillation by either method relieved breathlessness in those with CAO and was comfortable and well tolerated. 5. In normal subjects for was discrete and varied little with respiration. Maximum savings occurred around for (5–10 Hz). 6. In CAO, there was no obvious single resonant frequency and flow and pressure signals were intermittently in phase over a band of about 10 Hz. Thus the reductions in minute ventilation were only loosely related to for (13–26 Hz). Neither group reduced VE at foc (65–75 Hz). 7. OHFO has considerable potential in the management of patients with CAO, where it may be of value as an assistance to breathing and in the relief of breathlessness. ECWC, although effective in principle, is impractical by our methods and awaits the development of an acceptable delivery system.

Analysis of human chest wall motion using a two-compartment rib cage model

1992 ◽  
Vol 72 (4) ◽  
pp. 1338-1347 ◽  
Author(s):  
M. E. Ward ◽  
J. W. Ward ◽  
P. T. Macklem
Keyword(s):  
Chest Wall ◽  
Pressure Change ◽  
Pleural Pressure ◽  
Abdominal Pressure ◽  
Quiet Breathing ◽  
Transdiaphragmatic Pressure ◽  
Rib Cage ◽  
Mechanical Coupling ◽  
Chest Wall Motion ◽  
The Relationship

We present a model of chest wall mechanics that extends the model described previously by Macklem et al. (J. Appl. Physiol. 55: 547–557, 1983) and incorporates a two-compartment rib cage. We divide the rib cage into that apposed to the lung (RCpul) and that apposed to the diaphragm (RCab). We apply this model to determine rib cage distortability, the mechanical coupling between RCpul and RCab, the contribution of the rib cage muscles to the pressure change during spontaneous inspiration (Prcm), and the insertional component of transdiaphragmatic pressure in humans. We define distortability as the relationship between distortion and transdiaphragmatic pressure (Pdi) and mechanical coupling as the relationship between rib cage distortion and the pressure acting to restore the rib cage to its relaxed configuration (Plink), as assessed during bilateral transcutaneous phrenic nerve stimulation. Prcm was calculated at end inspiration as the component of the pressure displacing RCpul not accounted for by Plink or pleural pressure. Prcm and Plink were approximately equal during quiet breathing, contributing 3.7 and 3.3 cmH2O on average during breaths associated with a change in Pdi of 3.9 cmH2O. The insertional component of Pdi was measured as the pressure acting on RCab not accounted for by the change in abdominal pressure during an inspiration without rib cage distortion and was 40 +/- 12% (SD) of total Pdi. We conclude that there is substantial resistance of the human rib cage to distortion, that, along with rib cage muscles, contributes importantly to the fall in pleural pressure over the costal surface of the lung.

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