Regional ventilation during spontaneous breathing and mechanical ventilation in dogs

1987 ◽  
Vol 63 (6) ◽  
pp. 2467-2475 ◽  
Author(s):  
R. D. Hubmayr ◽  
J. R. Rodarte ◽  
B. J. Walters ◽  
F. M. Tonelli
Keyword(s):  
Mechanical Ventilation ◽  
Chest Wall ◽  
Spontaneous Breathing ◽  
Vertical Gradient ◽  
Lung Parenchyma ◽  
Regional Ventilation ◽  
Regional Lung ◽  
Residual Capacity ◽  
Wall Deformation ◽  
Diaphragm Motion

We evaluated the effects of the different patterns of chest wall deformation that occur with different body positions and modes of breathing on regional lung deformation and ventilation. Using the parenchymal marker technique, we determined regional lung behavior during mechanical ventilation and spontaneous breathing in five anesthetized recumbent dogs. Regional lung behavior was related to the patterns of diaphragm motion estimated from X-ray projection images obtained at functional residual capacity (FRC) and end inspiration. Our results indicate that 1) in the prone and supine positions, FRC was larger during mechanical ventilation than during spontaneous breathing; 2) there were significant differences in the patterns of diaphragm motion and regional ventilation between mechanical ventilation and spontaneous breathing in both body positions; 3) in the supine position only, there was a vertical gradient in lung volume at FRC; 4) in both positions and for both modes of breathing, regional ventilation was nonlinearly related to changes in lobar and overall lung volumes; and 5) different patterns of diaphragm motion caused different sliding motions and differential rotations of upper and lower lobes. Our results are inconsistent with the classic model of regional ventilation, and we conclude that the distribution of ventilation is determined by a complex interaction of lung and chest wall shapes and by the motion of the lobes relative to each other, all of which help to minimize distortion of the lung parenchyma.

Regional intrapulmonary gas distribution in awake and anesthetized-paralyzed prone man

1978 ◽  
Vol 45 (4) ◽  
pp. 528-535 ◽  
Author(s):  
K. Rehder ◽  
T. J. Knopp ◽  
A. D. Sessler
Keyword(s):  
Mechanical Ventilation ◽  
Vertical Distribution ◽  
Vertical Gradient ◽  
Phase Iii ◽  
Residual Volume ◽  
Gas Distribution ◽  
Lung Volumes ◽  
Regional Lung ◽  
Residual Capacity ◽  
The Vertical Distribution

The intrapulmonary distribution of inspired gas (ventilation/unit lung volume, VI), functional residual capacity (FRC), closing capacity (CC), and the slope of phase III were determined in five awake and five anesthetized-paralyzed volunteers who were in the prone position with the abdomen unsupported. After induction of anesthesia-paralysis, FRC was less in four of five subjects and CC was consistently less. At FRC there was no difference in the vertical gradient of regional lung volumes between the awake and anesthetized-paralyzed prone subjects. Also, there was no difference in VI between the two states. The normalized slope of phase III decreased consistently with induction of anesthesia-paralysis, but the vertical distribution of a 133Xe bolus inhaled from residual volume was not different between the two states. The data of the study are compatible with 1) a pattern of expansion of the respiratory system during anesthesia-paralysis and mechanical ventilation different than that during spontaneous breathing and 2) a more uniform intraregional distribution of inspired gas and/or a different sequence of emptying during anesthesia-paralysis.

In vivo regional diaphragm function in dogs

1989 ◽  
Vol 67 (2) ◽  
pp. 655-662 ◽  
Author(s):  
J. Sprung ◽  
C. Deschamps ◽  
R. D. Hubmayr ◽  
B. J. Walters ◽  
J. R. Rodarte
Keyword(s):  
Mechanical Ventilation ◽  
Chest Wall ◽  
Spontaneous Breathing ◽  
Considerable Variability ◽  
Diaphragm Function ◽  
Left Hemidiaphragm ◽  
Anesthetized Dogs ◽  
Abdominal Surface ◽  
Crural Diaphragm

A biplane videofluorographic system was used to track the position of metallic markers affixed to the abdominal surface of the left hemidiaphragm in supine anesthetized dogs. Regional shortening was determined from intermarker distances of rows of markers placed along muscle bundles in the ventral, middle, and dorsal regions of the costal diaphragm and of one row on the crural diaphragm. Considerable variability of regional shortening was seen in a given row, which was reproducible on repeat study in individual dogs but which differed between mechanical ventilation and spontaneous breathing. There were no consistent patterns among dogs. Regional shortening obtained from the change in length of rows extending from chest wall to central tendon showed no consistent differences among dogs during spontaneous breathing. At equal tidal volumes, all regions (except the ventral costal diaphragm) shortened more during spontaneous breathing than during mechanical ventilation.

Chest wall motion and distribution of inspired gas in anesthetized supine dogs

1980 ◽  
Vol 49 (2) ◽  
pp. 279-286 ◽  
Author(s):  
E. R. Schmid ◽  
K. Rehder ◽  
T. J. Knopp ◽  
R. E. Hyatt
Keyword(s):  
Chest Wall ◽  
Wall Motion ◽  
Regional Distribution ◽  
Vertical Gradient ◽  
Spontaneous Respiration ◽  
Regional Ventilation ◽  
Muscle Paralysis ◽  
Rib Cage ◽  
Chest Wall Motion ◽  
Anterior Posterior

Changes in the anterior-posterior (AP) and lateral diameters of the rib cage and abdomen were assessed by magnetometry in seven anesthetized supine dogs during spontaneous respiration (SR) and mechanical ventilation after muscle paralysis (MV). Regional distribution of inspired gas was measured for both modes of ventilation by determining regional 133Xe clearances. Marked differences in chest wall motion were observed between SR and MV: during MV, the changes in lateral rib cage diameter from FRC to end inspiration were larger, and the changes in both abdominal diameters smaller than during SR. AP rib cage diameter changes were similar for both modes of ventilation. Inward motion of the lateral rib cage during initial inspiration was observed in four dogs during SR; it disappeared consistently with MV. Regional 133Xe clearances were not significantly different: there was no cephalocaudal gradient, and the vertical gradient in regional ventilation was similar with MV and SR. We conclude that significant changes in chest wall motion and shape are not necessarily associated with detectable differences in the distribution of regional ventilation.

Atelectasis and Chest Wall Shape during Halothane Anesthesia

1996 ◽  
Vol 85 (1) ◽  
pp. 49-59 ◽  
Author(s):  
David O. Warner ◽  
Mark A. Warner ◽  
Erik L. Ritman
Keyword(s):  
Mechanical Ventilation ◽  
Chest Wall ◽  
Human Subjects ◽  
Three Dimensional ◽  
Wall Structure ◽  
Dependent Lung ◽  
Halothane Anesthesia ◽  
Quiet Breathing ◽  
Residual Capacity ◽  
Young Subjects

Background Anesthesia produces atelectasis in the dependent areas of the lungs by mechanisms that remain unknown. It has been proposed that anesthesia produces a cephalad shift in the end-expiratory position of the diaphragm, which compresses the lungs and produces atelectasis. This study tested the hypothesis that the extent of atelectasis is correlated with the cephalad displacement of the dependent portion of the diaphragm produced by halothane anesthesia in healthy young human subjects. Methods Twelve volunteers (mean age 34 yr) were studied while awake and during approximately 1.2 minimum alveolar concentration halothane anesthesia. Chest wall configuration was determined using images of the thorax obtained by three-dimensional fast computed tomography. Functional residual capacity was measured by a nitrogen dilution technique. Measurements were performed during quiet breathing in all subjects and after paralysis with 0.1 mg/kg vecuronium and mechanical ventilation in six subjects. Atelectasis was assumed to be present in regions of the lung that showed radiographic attenuation values similar to solid organs such as the liver. Results Atelectasis in dependent lung regions was not apparent in scans performed while the subjects were awake. Anesthesia with spontaneous breathing increased the volume of atelectasis measured at end-expiration by more than 1 ml in 9 of 12 subjects. For all subjects, the volume of atelectasis was 29 +/- 10 ml (M +/- SE), representing 0.67 +/- 0.23% of the total thoracic volume. The distribution of atelectasis varied along the cephalocaudal axis, with less atelectasis in more cephalad transverse sections. Paralysis and mechanical ventilation significantly decreased the volume of atelectasis present at end-expiration. There was no correlation between the average amount of cephalad displacement of the most dependent region of the diaphragm and the amount of atelectasis, nor was there any correlation between the amount of atelectasis and anesthesia-induced changes in the end-expiratory position of any chest wall structure. Conclusions The dependent lung atelectasis produced by halothane anesthesia does not appear to be related to changes in the position of any single chest wall structure in these healthy young subjects, but rather to an interaction of several factors that remain to be identified.

scholarly journals Progression of regional lung strain and heterogeneity in lung injury: assessing the evolution under spontaneous breathing and mechanical ventilation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Daniel E. Hurtado ◽  
Benjamín Erranz ◽  
Felipe Lillo ◽  
Mauricio Sarabia-Vallejos ◽  
Pablo Iturrieta ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lung Injury ◽  
Spontaneous Breathing ◽  
Regional Lung ◽  
Lung Strain

Chest wall motion during spontaneous breathing and mechanical ventilation in dogs

1989 ◽  
Vol 66 (3) ◽  
pp. 1179-1189 ◽  
Author(s):  
D. O. Warner ◽  
S. Krayer ◽  
K. Rehder ◽  
E. L. Ritman
Keyword(s):  
Mechanical Ventilation ◽  
Chest Wall ◽  
Blood Volume ◽  
Spontaneous Breathing ◽  
High Speed ◽  
Gas Flow ◽  
Three Dimensional ◽  
Liquid Volume ◽  
Similar Amount ◽  
Rib Cage

We measured the volume change of the thoracic cavity (delta Vth) and the volumes displaced by the diaphragm (delta Vdi) and rib cage (delta Vrc) in six pentobarbital-anesthetized dogs lying supine. A high-speed X-ray scanner (dynamic spatial reconstructor) provided three-dimensional images of the thorax during spontaneous breathing and during mechanical ventilation with paralysis. Tidal volume (VT) was measured by integrating gas flow. Changes in thoracic liquid volume (delta Vliq, presumably caused by changes in thoracic blood volume) were calculated as delta Vth - VT. Absolute volume displaced by the rib cage was not significantly different during the two modes of ventilation. During spontaneous breathing, thoracic blood volume increased during inspiration; delta Vliq was 12.3 +/- 4.1% of delta Vth. During mechanical ventilation, delta Vliq was nearly zero. Configuration of the relaxed chest wall was similar during muscular relaxation induced by either pharmacological paralysis or hyperventilation. Expiratory muscle activity produced 50 +/- 11% of the delta Vth during spontaneous breathing. We conclude that at constant VT the volume displaced by the rib cage is remarkably similar during the transition from spontaneous breathing to mechanical ventilation, while both diaphragmatic volume displacement and changes in intrathoracic blood volume decrease by a similar amount.

Effect of gravity and posture on lung mechanics

2002 ◽  
Vol 93 (6) ◽  
pp. 2044-2052 ◽  
Author(s):  
D. Bettinelli ◽  
C. Kays ◽  
O. Bailliart ◽  
A. Capderou ◽  
P. Techoueyres ◽  
...  
Keyword(s):  
Chest Wall ◽  
Respiratory Mechanics ◽  
Lung Parenchyma ◽  
Lung Mechanics ◽  
Vertical Acceleration ◽  
Quiet Breathing ◽  
Supine Posture ◽  
Residual Capacity ◽  
Relationship Of ◽  
Substantial Change

The volume-pressure relationship of the lung was studied in six subjects on changing the gravity vector during parabolic flights and body posture. Lung recoil pressure decreased by ∼2.7 cmH2O going from 1 to 0 vertical acceleration (Gz), whereas it increased by ∼3.5 cmH2O in 30° tilted head-up and supine postures. No substantial change was found going from 1 to 1.8 Gz. Matching the changes in volume-pressure relationships of the lung and chest wall (previous data), results in a decrease in functional respiratory capacity of ∼580 ml at 0 Gz relative to 1 Gz and of ∼1,200 ml going to supine posture. Microgravity causes a decrease in lung and chest wall recoil pressures as it removes most of the distortion of lung parenchyma and thorax induced by changing gravity field and/or posture. Hypergravity does not greatly affect respiratory mechanics, suggesting that mechanical distortion is close to maximum already at 1 Gz. The end-expiratory volume during quiet breathing corresponds to the mechanical functional residual capacity in each condition.

Effect of regional chest wall restriction on regional lung function

1980 ◽  
Vol 49 (4) ◽  
pp. 655-662 ◽  
Author(s):  
L. Forkert
Keyword(s):  
Lung Function ◽  
Normal Distribution ◽  
Chest Wall ◽  
Functional Residual Capacity ◽  
Scintillation Detectors ◽  
Rib Cage ◽  
Regional Lung Function ◽  
Regional Lung ◽  
Midaxillary Line ◽  
Residual Capacity

The effect of impeding regional chest wall excursion on regional lung function was assessed. Fourteen subjects were studied while seated in a volume-displacement plethysmography. The lower rib cage and epigastrium were restricted with an inextensible binder. Because such restriction increases lung recoil and diminishes functional residual capacity (FRC), all measurements were made at the unstrapped FRC (FRCus). Regional excursion of the chest wall was measured with magnetometers placed anteroposteriorly at the sternomanubrial angle, the xyphoid, and umbilicus and transversely at the level of the xyphoid at the midaxillary line. Regional lung function was assessed by measuring the distribution of inspired boluses and washout of 133Xe with scintillation detectors positioned against the subject's back at the apical, middle, and basal regions. Restriction of the lower chest wall impeded expansion of the lower rib cage and diminished the distribution of inspired gas to and washout of the lung bases. The upper rib cage expanded normally and was associated with an increased distribution of inspired gas and normal distribution of washout to the apices. These results suggest that regional lung function was dependent on regional rib cage excursion.

scholarly journals Imaging atelectrauma in Ventilator-Induced Lung Injury using 4D X-ray microscopy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luca Fardin ◽  
Ludovic Broche ◽  
Goran Lovric ◽  
Alberto Mittone ◽  
Olivier Stephanov ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Lung Injury ◽  
Lung Parenchyma ◽  
Contrast Imaging ◽  
Barrier Dysfunction ◽  
Mechanically Ventilated ◽  
Ventilator Induced Lung Injury ◽  
Regional Lung ◽  
Ventilation Strategies ◽  
Protective Mechanical Ventilation

AbstractMechanical ventilation can damage the lungs, a condition called Ventilator-Induced Lung Injury (VILI). However, the mechanisms leading to VILI at the microscopic scale remain poorly understood. Here we investigated the within-tidal dynamics of cyclic recruitment/derecruitment (R/D) using synchrotron radiation phase-contrast imaging (PCI), and the relation between R/D and cell infiltration, in a model of Acute Respiratory Distress Syndrome in 6 anaesthetized and mechanically ventilated New-Zealand White rabbits. Dynamic PCI was performed at 22.6 µm voxel size, under protective mechanical ventilation [tidal volume: 6 ml/kg; positive end-expiratory pressure (PEEP): 5 cmH2O]. Videos and quantitative maps of within-tidal R/D showed that injury propagated outwards from non-aerated regions towards adjacent regions where cyclic R/D was present. R/D of peripheral airspaces was both pressure and time-dependent, occurring throughout the respiratory cycle with significant scatter of opening/closing pressures. There was a significant association between R/D and regional lung cellular infiltration (p = 0.04) suggesting that tidal R/D of the lung parenchyma may contribute to regional lung inflammation or capillary-alveolar barrier dysfunction and to the progression of lung injury. PEEP may not fully mitigate this phenomenon even at high levels. Ventilation strategies utilizing the time-dependence of R/D may be helpful in reducing R/D and associated injury.

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