Evidence for increased intrathoracic fluid volume in man at high altitude

1979 ◽  
Vol 47 (4) ◽  
pp. 670-676 ◽  
Author(s):  
J. J. Jaeger ◽  
J. T. Sylvester ◽  
A. Cymerman ◽  
J. J. Berberich ◽  
J. C. Denniston ◽  
...  
Keyword(s):  
Pulmonary Edema ◽  
High Altitude ◽  
Transpulmonary Pressure ◽  
Fluid Volume ◽  
Pulmonary Mechanics ◽  
Volume Curve ◽  
Extravascular Fluid ◽  
Pressure Volume Curve ◽  
Transthoracic Electrical Impedance ◽  
Extravascular Fluid Volume

To determine if subclinical pulmonary edema occurs commonly at high altitude, 25 soldiers participated in two consecutive 72-h field exercises, the first at low altitude (200–875 m) and the second at high altitude (3,000–4,300 m). Various aspects of ventilatory function and pulmonary mechanics were measured at 0, 36, and 72 h of each exercise. Based on physical examination and chest radiographs there was no evidence of pulmonary edema at high altitude. There was, however, an immediate and sustained decrease in vital capacity and transthoracic electrical impedance as well as a clockwise rotation of the transpulmonary pressure-volume curve. In contrast, closing capacity and residual volume did not change immediately upon arrival at high altitude but did increase later during the exposure. These observations are consistent with an abrupt increase in thoracic intravascular fluid volume upon arrival at high altitude followed by a more gradual increase in extravascular fluid volume in the peribronchial spaces of dependent lung regions.

Improved measurements of shear modulus and pleural membrane tension of the lung

1979 ◽  
Vol 47 (1) ◽  
pp. 175-181 ◽  
Author(s):  
M. A. Hajji ◽  
T. A. Wilson ◽  
S. J. Lai-Fook
Keyword(s):  
Shear Modulus ◽  
Transpulmonary Pressure ◽  
Elastic Half Space ◽  
Concentrated Force ◽  
Membrane Area ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Pressure Independent ◽  
Work Done ◽  
The Continuum

The continuum solution for the deformation of an elastic half space covered by a membrane is used to interpret measurements of the indentation of lung lobes under a column of fluid. The shear modulus mu of the underlying parenchyma is found to be approximately 0.7 times transpulmonary pressure, independent of species size. The tension in the pleural membrane T increases rapidly with increasing membrane area. For dog lungs, the value of T is 10(3) to 10(4) dyn/cm. For the larger species tested, pigs and horses, T is larger. The continuum solution shows that a concentrated force applied to the pleural surface is distributed over a distance T/mu as it is transmitted across the pleural membrane. The membrane is important in determining the displacement produced by forces that act within a region that is small compared to this distance, approximately 2 cm for dog lungs. By comparing the tension-area curve of the pleural membrane with the pressure-volume curve of the lobe, it is found that the pleural membrane contributes about 20% of the work done by the lung during deflation.

Series distribution of airway collapsibility in dogs

1981 ◽  
Vol 50 (2) ◽  
pp. 325-333 ◽  
Author(s):  
M. Nakamura ◽  
H. Sasaki ◽  
K. Sekizawa ◽  
M. Ishii ◽  
T. Takishima ◽  
...  
Keyword(s):  
Transpulmonary Pressure ◽  
Forced Expiration ◽  
Peripheral Airways ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Airway Collapsibility

We studied the series distribution of collapsibility in four different-sized airways in dogs. The trachea and the extrapulmonary main bronchi in situ were isolated from the rest of the lungs by glued beads of 6-12 mm OD. In excised dog lungs, the intrapulmonary large and small bronchi were isolated from the rest of the lung by glued beads of 1-9 mm OD. Pressure-volume relationships were measured directly in the trachea and in the extrapulmonary bronchi; those of the intrapulmonary bronchi were derived from orthogonal bronchograms. Airway collapsibility, defined as the slope of the pressure-volume curve, was found to increase in all airways as transpulmonary pressure (PL) decreased. At PL 30 cmH2O there was little difference of airway collapsibility among the different sized airways; but, as PL decreased, the peripheral airways became more collapsible than the central airways. It is concluded that the tissues surrounding the trachea provided as much or more stiffness than did the lung tissues that surrounded the intrapulmonary airways. The larger collapsibility in the peripheral airways. The larger collapsibility in the peripheral airways relative to that of the central airways at lower PL may account for the peripheral migration of the flow-limiting segment during forced expiration.

Gravitational independence of single-breath washout tests in recumbent dogs

1988 ◽  
Vol 64 (2) ◽  
pp. 642-648 ◽  
Author(s):  
S. Tomioka ◽  
S. Kubo ◽  
H. J. Guy ◽  
G. K. Prisk
Keyword(s):  
Prone Position ◽  
Regional Distribution ◽  
Transpulmonary Pressure ◽  
Phase Iii ◽  
Closing Volume ◽  
Body Rotation ◽  
Single Breath ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Phase Iv

To examine the mechanisms of lung filling and emptying, Ar-bolus and N2 single-breath washout tests were conducted in 10 anesthetized dogs (prone and supine) and in three of those dogs with body rotation. Transpulmonary pressure was measured simultaneously, allowing identification of the lung volume above residual volume at which there was an inflection point in the pressure-volume curve (VIP). Although phase IV for Ar was upward, phase IV for N2 was small and variable, especially in the prone position. No significant prone to supine differences in closing capacity for Ar were seen, indicating that airway closure was generated at the same lung volumes. The maximum deflections of phase IV for Ar and N2 from extrapolated phase III slopes were smaller in the prone position, suggesting more uniform tracer gas concentrations across the lungs. VIP was smaller than the closing volume for Ar, which is consistent with the effects of well-developed collateral ventilation in dogs. Body rotation tests in three dogs did not generally cause an inversion of phase III or IV. We conclude that in recumbent dogs regional distribution of ventilation is not primarily determined by the effect of gravity, but by lung, thorax, and mediastinum interactions and/or differences in regional mechanical properties of the lungs.

Plasma volume and extravascular fluid volume during pregnancy and the puerperium

1949 ◽  
Vol 57 (3) ◽  
pp. 471-481 ◽  
Author(s):  
William L. Caton ◽  
Charles C. Roby ◽  
Duncan E. Reid ◽  
John G. Gibson
Keyword(s):  
Plasma Volume ◽  
Fluid Volume ◽  
Extravascular Fluid ◽  
Extravascular Fluid Volume

Positive airway pressure and vertical transpulmonary pressure gradient in man

1975 ◽  
Vol 38 (5) ◽  
pp. 896-899 ◽  
Author(s):  
K. Rehder ◽  
N. Abboud ◽  
J. R. Rodarte ◽  
R. E. Hyatt
Keyword(s):  
Continuous Positive Airway Pressure ◽  
Pressure Gradient ◽  
Airway Pressure ◽  
Positive Airway Pressure ◽  
Transpulmonary Pressure ◽  
Vertical Gradient ◽  
Normal Subjects ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Consistent Change

Static transpulmonary pressure (Pao-Pes) and the vertical gradient of transpulmonary pressure were determined in five sitting conscious normal subjects at mean airway pressures of 0 (ambient), 11, and 21 cmH2O. All subjects exhibited a nonuniform transpulmonary pressure gradient down the esophagus. The vertical pressure gradient was consistently larger in the lower (8–20cm below esophageal artifact) than in the middle region (0–8cm) of the esophagus. The gradient was not significantly altered by continuous positive airway pressure (11 and 21 cmH2O) or by changes in lung volume (60, 70, and 80% of total lung capacity (TLC)). Continuous positive airway pressure also did not result in a consistent change of the overall static pressure-volume curve of the lung. There was a small but statistically significant increase in TLC with each increase in airway pressure.

Effect of transpulmonary and vascular pressures on rate of pulmonary edema formation

1977 ◽  
Vol 43 (1) ◽  
pp. 14-19 ◽  
Author(s):  
H. S. Goldberg ◽  
W. Mitzner ◽  
G. Batra
Keyword(s):  
Weight Gain ◽  
Pulmonary Edema ◽  
Transpulmonary Pressure ◽  
Fluid Accumulation ◽  
Edema Formation ◽  
Extravascular Fluid ◽  
Zone Ii ◽  
Vascular Beds

The effect of transpulmonary pressure (Ptp) on rate of extravascular fluid accumulation in isolated canine left lower lobes perfused at constant vascular pressures was investigated. Changes in rate of extravascular fluid accumulation were estimated by changes in rate of slow weight gain. Mean inflow pressure (Ppa) was constant at 34 cmH2O. Mean outflow pressure (Ppv) was constant at either 27.2 cmH2O or 13.6 cmH2O. When increasing Ptp is associated with a derecruitment of vascular beds as the lung changes from predominantly zone III toward zone II, or zone I, there is a decrease in rate of weight gain. When increasing Ptp is not associated with a derecruitment of vascular beds, it is impossible on the basis of these experiments to predict the change in rate of weight gain.

Distortion of submerged dog lung lobes

1985 ◽  
Vol 59 (2) ◽  
pp. 521-527 ◽  
Author(s):  
L. E. Olson ◽  
T. A. Wilson ◽  
J. R. Rodarte
Keyword(s):  
Buoyancy Force ◽  
Transpulmonary Pressure ◽  
Vertical Position ◽  
Pressure Curve ◽  
Engineering Analysis ◽  
Vertical Strain ◽  
Analytical Results ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Lung Lobes

The conically shaped caudal lobes of dog lungs were submerged, tip downward in saline, and the lateral surfaces of the lobes were thereby exposed to a hydrostatic gradient in transpulmonary pressure. The force that was required to balance the buoyancy was applied through a clip attached to the tip of the lobe. The locations of metal markers implanted in the parenchyma and attached to the surface were tracked, and regional volume and the horizontal and vertical components of strain were obtained as functions of vertical position. An engineering analysis of the deformation is qualitatively consistent with the data, but the predicted strains are larger than the observed strains. From the experimental and analytical results, we conclude that, for this deformation, the regional volume-local transpulmonary pressure curve closely follows the pressure-volume curve because negative horizontal strains nearly balance the positive vertical strain caused by the buoyancy force.

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