Effect of volume and volume history of the lungs on pulmonary shunt flow

1964 ◽  
Vol 207 (1) ◽  
pp. 235-238 ◽  
Author(s):  
Nicholas R. Anthonisen
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Full Range ◽  
Transpulmonary Pressure ◽  
Pulmonary Shunt ◽  
Shunt Flow ◽  
Lung Capacity ◽  
Surface Active Properties ◽  
History Of ◽  
Surface Active

Relative pulmonary shunt flow (Qs/Qt), was measured in denitrogenated open-chested cats during apnea over the full range of lung volumes. The particular lung volume and transpulmonary pressure were also measured. When completely collapsed lungs were inflated, Qs/Qt decreased sharply to 3% at total lung capacity (TLC). During deflation from TLC Qs/Qt was insensitive to changes in lung volume. Qs/Qt remained low during reinflation after deflation from TLC. These changes in shunt flow can be interpreted as due to either recruitment or collapse of gas exchange units during lung volume change. It appears that completely collapsed lungs inflate very unevenly but that deflation from TLC proceeds remarkably evenly. Reinflation after deflation from TLC also seems to proceed evenly, and the manifest pressure-volume hysteresis is most likely due to hysteresis of the surface-active properties of the alveolar lining material.

Role of alveolar recruitment in lung inflation: influence on pressure-volume hysteresis

1983 ◽  
Vol 55 (4) ◽  
pp. 1321-1332 ◽  
Author(s):  
G. C. Smaldone ◽  
W. Mitzner ◽  
H. Itoh
Keyword(s):  
Lung Volume ◽  
Linear Dimension ◽  
Total Lung Capacity ◽  
Alveolar Recruitment ◽  
Rapid Cycling ◽  
Lung Inflation ◽  
Lung Capacity ◽  
History Of

The behavior of terminal lung units (alveoli) with changes in lung volume is controversial. For example, different investigators using similar techniques have suggested that alveoli expand homogeneously or, conversely, get smaller with increases in lung volume. We studied this problem by filling excised dog lobes with monodisperse aerosol and observing deposition at zero airflow. Under these conditions, the deposition of particles is inversely proportional to a mean alveolar linear dimension (ALD). With this technique, changes in ALD were assessed as the lung ventilated along its pressure-volume (PV) curve. PV curves were generated using a rapid cycling technique that minimized trapping and allowed reversible regulation of inflation-deflation hysteresis. Irreversible changes in PV hysteresis were assessed by rinsing the lung with Tween. With significant PV hysteresis, the ALD progressively decreased with inflation to total lung capacity (TLC). With deflation from TLC, the ALD was unchanged until low volumes were reached, when it decreased markedly. When PV hysteresis was minimized (reversibly or irreversibly), inflation and deflation ALD were superimposed. These data are consistent with progressive alveolar recruitment with inflation to TLC and derecruitment with deflation. The correlation between alveolar dimensions and PV hysteresis suggests that shifts in the PV curve can be accounted for by changes in the population of units. The number open at any given point is determined by the dynamic history of inflation.

Changes in shunt flow, compliance, and volume of lungs during apneic oxygenation

1964 ◽  
Vol 207 (1) ◽  
pp. 239-241 ◽  
Author(s):  
Nicholas R. Anthonisen
Keyword(s):  
Total Lung Capacity ◽  
Surface Characteristics ◽  
The Other ◽  
Time Dependent ◽  
Pulmonary Shunt ◽  
Lung Volumes ◽  
Apneic Oxygenation ◽  
Shunt Flow ◽  
Lung Capacity ◽  
Serial Measurements

Open-chested denitrogenated cats were studied during 30-min periods of apneic oxygenation. Two lung volumes were selected, one about 25% of total lung capacity (TLC), and the other one about 55% of TLC. Serial measurements were made during apnea of pulmonary shunt flow (Qs/Qt) and static pulmonary compliance (Cl). Lung volumes were measured at the beginning and end of the period of apnea. Apneic oxygenation at 25% TLC regularly was associated with increasing Qs/Qt, decreasing Cl, and loss of lung volume signifying atelectasis. None of these phenomena were observed at 55% TLC. These results are discussed as they relate to time-dependent changes in the surface characteristics of the alveolar lining.

Rib cage and abdominal restrictions have different effects on lung mechanics

1980 ◽  
Vol 49 (6) ◽  
pp. 946-952 ◽  
Author(s):  
C. A. Bradley ◽  
N. R. Anthonisen
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Lung Mechanics ◽  
Elastic Recoil ◽  
Rib Cage ◽  
Lung Capacity ◽  
Single Breath ◽  
Restrictive Procedures ◽  
Maximum Expiratory Flow ◽  
Per Se

The effects of a variety of restrictive procedures on lung mechanics were studied in eight healthy subjects. Rib cage restriction decreased total lung capacity (TLC) by 43% and significantly increased elastic recoil and maximum expiratory flow (MEF). Subsequent immersion of four subjects with rib cage restriction resulted in no further change in either parameter; shifts of blood volume did not reverse recoil changes during rib cage restriction. Abdominal restriction decreased TLC by 40% and increased MEF and elastic recoil, but recoil was increased significantly less than was the case with rib cage restriction. Further, at a given recoil pressure, MEF was less during rib cage restriction than during either abdominal restriction or no restriction. Measurements of the unevenness of inspired gas distribution by the single-breath nitrogen technique showed increased unevenness during rib cage restriction, which was significantly greater than that during abdominal restriction. We conclude that lung volume restriction induces changes in lung function, but the nature of these changes depends on how the restriction is applied and therefore cannot be ascribed to low lung volume breathing per se.

Inspiratory muscles during exercise: a problem of supply and demand

1988 ◽  
Vol 64 (6) ◽  
pp. 2482-2489 ◽  
Author(s):  
P. Leblanc ◽  
E. Summers ◽  
M. D. Inman ◽  
N. L. Jones ◽  
E. J. Campbell ◽  
...  
Keyword(s):  
Lung Volume ◽  
Static Pressure ◽  
Total Lung Capacity ◽  
Supply And Demand ◽  
Normal Subjects ◽  
Esophageal Pressure ◽  
Maximum Exercise ◽  
Lung Capacity ◽  
Inspiratory Muscles ◽  
Residual Capacity

The capacity of inspiratory muscles to generate esophageal pressure at several lung volumes from functional residual capacity (FRC) to total lung capacity (TLC) and several flow rates from zero to maximal flow was measured in five normal subjects. Static capacity was 126 +/- 14.6 cmH2O at FRC, remained unchanged between 30 and 55% TLC, and decreased to 40 +/- 6.8 cmH2O at TLC. Dynamic capacity declined by a further 5.0 +/- 0.35% from the static pressure at any given lung volume for every liter per second increase in inspiratory flow. The subjects underwent progressive incremental exercise to maximum power and achieved 1,800 +/- 45 kpm/min and maximum O2 uptake of 3,518 +/- 222 ml/min. During exercise peak esophageal pressure increased from 9.4 +/- 1.81 to 38.2 +/- 5.70 cmH2O and end-inspiratory esophageal pressure increased from 7.8 +/- 0.52 to 22.5 +/- 2.03 cmH2O from rest to maximum exercise. Because the estimated capacity available to meet these demands is critically dependent on end-inspiratory lung volume, the changes in lung volume during exercise were measured in three of the subjects using He dilution. End-expiratory volume was 52.3 +/- 2.42% TLC at rest and 38.5 +/- 0.79% TLC at maximum exercise.

Costal diaphragm curvature in the dog

1993 ◽  
Vol 75 (2) ◽  
pp. 527-533 ◽  
Author(s):  
A. M. Boriek ◽  
S. Liu ◽  
J. R. Rodarte
Keyword(s):  
Mechanical Ventilation ◽  
Muscle Fiber ◽  
Lung Volume ◽  
Spontaneous Breathing ◽  
Total Lung Capacity ◽  
Muscle Fibers ◽  
Transdiaphragmatic Pressure ◽  
Lung Capacity ◽  
Principal Axes ◽  
Quadratic Surface

The curvature of the midcostal region of the diaphragm in seven dogs was determined at functional residual capacity (FRC) and end inspiration during spontaneous breathing and mechanical ventilation and at total lung capacity in the prone and supine positions. Metallic markers were attached to muscle fibers on the abdominal surface of the diaphragm, and the dog was allowed to recover from surgery. The three-dimensional positions of the markers were determined by biplane videofluoroscopy. A quadratic surface was fit to the bead positions. The principal axes of the quadratic surface lie nearly along and perpendicular to the muscle fibers. In both the supine and prone positions, the values of the principal curvatures were similar at FRC and end inspiration during spontaneous breathing, when muscle tension and transdiaphragmatic pressure both increase with increasing lung volume, and during mechanical ventilation and passive inflation to total lung capacity, when both decrease relative to their magnitude at FRC. No abrupt change of curvature, which might be expected at the edge of the zone of apposition, was apparent. The curvature along the muscle fiber was 0.35 +/- 0.07 cm-1; the curvature perpendicular to the muscle fiber was much smaller, 0.06 +/- 0.01 cm-1. The costal region of the diaphragm displaces and shortens as lung volume increases, but its shape, as described by its curvatures, does not change substantially.

Elastic properties of the lung in acute induced asthma

1983 ◽  
Vol 54 (1) ◽  
pp. 152-158 ◽  
Author(s):  
D. Rodenstein ◽  
D. C. Stanescu
Keyword(s):  
Lung Volume ◽  
Static Pressure ◽  
Total Lung Capacity ◽  
Esophageal Pressure ◽  
Elastic Recoil ◽  
Rapid Loss ◽  
Asthmatic Patients ◽  
Clear Cut ◽  
Lung Capacity ◽  
Significant Change

In acute induced asthma, plethysmographic total lung capacity (TLCm) was reported to increase and lung elastic recoil [Pst(L)] to decrease. The increase in TLC is spurious (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 52: 939–954, 1982), so that the rapid loss in Pst(L) could be due to errors in lung volume. We studied seven asthmatic patients before and during an induced bronchospasm. TLC was derived simultaneously from mouth and esophageal pressure vs. plethysmographic volume plots (TLCm and TLCes, respectively). Before bronchospasm, TLCm and TLCes were similar. During bronchospasm average TLCm increased, from 7.30 +/- 1.34 (SD) to 8.12 +/- 1.49 liters (P less than 0.001), whereas TLCes did not (P greater than 0.60). Static pressure-volume curves, derived from TLCes (P-Ves), were superimposed on prechallenge curves or only slightly shifted to the left, whereas those derived from TLCm (P-Vm) showed a clear-cut parallel shift to the left. At 70% of control TLC there was no significant change in Pst(L) measured from P-Ves curves (7.3 +/- 3.1 cmH2O before bronchospasm; 6.7 +/- 2.3 cmH2O during bronchospasm, P greater than 0.10), whereas Pst(L) measured from P-Vm curves decreased from 7.3 +/- 3.1 to 5.1 +/- 2.4 cmH2O (P less than 0.01). No significant change in Pst(L) at TLC was observed during bronchospasm. We conclude that in our patients acute decrease in Pst(L) during induced asthma was artifactual, secondary to lung volume overestimation by body plethysmography.

Effect of Lung Volume on Voice Onset Time (VOT)

1993 ◽  
Vol 36 (3) ◽  
pp. 516-520 ◽  
Author(s):  
Jeannette D. Hoit ◽  
Nancy Pearl Solomon ◽  
Thomas J. Hixon
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Voice Onset Time ◽  
Onset Time ◽  
Speech Disorders ◽  
Residual Volume ◽  
Healthy Individuals ◽  
Lung Volumes ◽  
Lung Capacity

This investigation was designed to test the hypothesis that voice onset time (VOT) varies as a function of lung volume. Recordings were made of five men as they repeated a phrase containing stressed /pi/ syllables, beginning at total lung capacity and ending at residual volume. VOT was found to be longer at high lung volumes and shorter at low lung volumes in most cases. This finding points out the need to take lung volume into account when using VOT as an index of laryngeal behavior in both healthy individuals and those with speech disorders.

Comparison of balloon and transducer catheters for estimating lung elasticity

1992 ◽  
Vol 72 (1) ◽  
pp. 231-235 ◽  
Author(s):  
J. A. Panizza ◽  
K. E. Finucane
Keyword(s):  
Elastic Properties ◽  
Static Pressure ◽  
Total Lung Capacity ◽  
Least Squares Method ◽  
Balloon Catheter ◽  
Transpulmonary Pressure ◽  
Repeatability Coefficient ◽  
Lung Capacity ◽  
Acceptable Alternative ◽  
Paired T Test

Pleural pressure is usually estimated with a balloon catheter (BC) positioned in the middle third of the esophagus. An alternate method, which avoids potential inaccuracies associated with changes in balloon volume, is a catheter-mounted transducer (CMT) system. To assess the accuracy of a CMT system in defining the elastic properties of the lungs, we compared the static pressure-volume (PV) properties of the lungs measured sequentially with CMT and BC systems in six healthy subjects each on two occasions, relating static transpulmonary pressure (Pst,L) to lung volume during interrupted exhalations from total lung capacity (TLC). PV data were fitted with an exponential function (least-squares method), and the exponent (k) was used to define the shape of the PV curve; position was defined by Pst,L at TLC and at 90 and 60% TLC. These data were examined for agreement (paired t test) and repeatability (coefficient of repeatability). No significant differences were demonstrated: k was 0.10 +/- 0.02 and 0.11 +/- 0.03 (SD) and Pst,L at 60% TLC was 8.27 +/- 2.09 and 8.37 +/- 1.63 cmH2O for the CMT and BC systems, respectively. The coefficient of repeatability for each parameter was not significantly different but was consistently less with the BC, suggesting better repeatability. We conclude that a CMT system is an acceptable alternative to a BC system for defining the elastic properties of lungs.

Lung volume dependence of esophageal pressure in the neck

1985 ◽  
Vol 59 (6) ◽  
pp. 1849-1854 ◽  
Author(s):  
I. G. Brown ◽  
P. A. McClean ◽  
P. M. Webster ◽  
V. Hoffstein ◽  
N. Zamel
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Balloon Catheter ◽  
Esophageal Pressure ◽  
Lower Esophagus ◽  
Tissue Pressure ◽  
Lung Capacity ◽  
Volume Dependence ◽  
Conflicting Evidence ◽  
Cervical Trachea

There is conflicting evidence in the literature regarding tissue pressure in the neck. We studied esophageal pressure along cervical and intrathoracic esophageal segments in six healthy men to determine extramural pressure for the cervical and intrathoracic airways. A balloon catheter system with a 1.5-cm-long balloon was used to measure intraesophageal pressures. It was positioned at 2-cm intervals, starting 10 cm above the cardiac sphincter and ending at the cricopharyngeal sphincter. We found that esophageal pressures became more negative as the balloon catheter moved from intrathoracic to cervical segments, until the level of the cricopharyngeal sphincter was reached. At total lung capacity, esophageal pressures were -10.5 +/- 2.9 (SE) cmH2O in the lower esophagus, -18.9 +/- 3.0 just within the thorax, and -21.3 +/- 2.73 within 2 cm of the cricopharyngeal sphincter. The variation in mouth minus esophageal pressure with lung volume was similar in cervical and thoracic segments. We conclude that the subatmospheric tissue pressure applied to the posterior membrane of the cervical trachea results in part from transmission of apical pleural pressure into the neck. Transmural pressure for cervical and thoracic tracheal segments is therefore similar.

Effects of lung volume on collateral and airways resistance in man

1979 ◽  
Vol 46 (1) ◽  
pp. 67-73 ◽  
Author(s):  
C. R. Inners ◽  
P. B. Terry ◽  
R. J. Traystman ◽  
H. A. Menkes
Keyword(s):  
Functional Residual Capacity ◽  
Lung Volume ◽  
Total Lung Capacity ◽  
Lung Capacity ◽  
Residual Capacity ◽  
Collateral Pathways ◽  
Flow Through ◽  
Airways Resistance ◽  
Young Subjects ◽  
The Relationship

The effects of changing lung volume (VL) on collateral resistance (Rcoll) and total airways resistance (Raw) were compared in six young volunteers. At functional residual capacity (FRC) = 55% total lung capacity (TLC), mean Rcoll was 4,664 +/- 1,518 (SE) cmH2O/(l/s) and mean Raw was 1.57 +/- 0.11 (SE) cmH2O/l/s). When VL increased to 80% TLC, Rcoll decreased by 63.3 +/- 7.8%, and Raw decreased by 50.3 +/- 4.2 (SE) %. The decrease in Rcoll with increasing lung volume was not statistically different from that of Raw (P less than 0.05). If the airways obstructed for measurements of Rcoll served between 2 and 5% of the lungs, then Rcoll was approximately 50 times as great as the resistance to flow through airways serving the same volume of lung at FRC. The relationship did not change significantly when VL increased by 25% TLC. If changes in Raw reflect changes in airways supplying sublobar portions of lung, these results indicate that there is no tendency for the redistribution of ventilation through airways and collateral pathways with changes in VL in young subjects.

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