Lung Volume Dependence of Pharyngeal Cross-Sectional Area by Acoustic Pharyngometry

2002 ◽  
Vol 126 (2) ◽  
pp. 164-171 ◽  
Author(s):  
Ibrahim Kamal
Keyword(s):  
Lung Volume ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Volume Dependence ◽  
Acoustic Pharyngometry

Effect of position and lung volume on upper airway geometry

1987 ◽  
Vol 63 (1) ◽  
pp. 375-380 ◽  
Author(s):  
J. M. Fouke ◽  
K. P. Strohl
Keyword(s):  
Lung Volume ◽  
Supine Position ◽  
Upper Airway ◽  
Upright Position ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Position Change ◽  
Cross Sectional ◽  
Acoustic Reflection ◽  
Residual Capacity

The occurrence of upper airway obstruction during sleep and with anesthesia suggests the possibility that upper airway size might be compromised by the gravitational effects of the supine position. We used an acoustic reflection technique to image airway geometry and made 180 estimates of effective cross-sectional area as a function of distance along the airway in 10 healthy volunteers while they were supine and also while they were seated upright. We calculated z-scores along the airway and found that pharyngeal cross-sectional area was smaller in the supine than in the upright position in 9 of the 10 subjects. For all subjects, pharyngeal cross-sectional area was 23 +/- 8% smaller in the supine than in the upright position (P less than or equal to 0.05), whereas glottic and tracheal areas were not significantly altered. Because changing from the upright to the supine position causes a decrease in functional residual capacity (FRC), six of these subjects were placed in an Emerson cuirass, which was evacuated producing a positive transrespiratory pressure so as to restore end-expiratory lung volume to that seen before the position change. In the supine posture an increase in end-expiratory lung volume did not change the cross-sectional area at any point along the airway. We conclude that pharyngeal cross-sectional area decreases as a result of a change from the upright to the supine position and that the mechanism of this change is independent of the change in FRC.

Mild Intermittent Asthma: CT Assessment of Bronchial Cross-sectional Area and Lung Attenuation at Controlled Lung Volume

Radiology ◽  
2002 ◽  
Vol 223 (1) ◽  
pp. 181-187 ◽  
Author(s):  
Catherine Beigelman-Aubry ◽  
André Capderou ◽  
Philippe A. Grenier ◽  
Christian Straus ◽  
Marie-Hélène Becquemin ◽  
...  
Keyword(s):  
Lung Volume ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Intermittent Asthma

Configuration of maximum expiratory flow-volume curve: model experiments with physiological implications

1985 ◽  
Vol 58 (4) ◽  
pp. 1305-1313 ◽  
Author(s):  
O. F. Pedersen ◽  
R. H. Ingram
Keyword(s):  
Lung Volume ◽  
Cross Sectional Area ◽  
Flow Volume ◽  
Sectional Area ◽  
Cross Sectional ◽  
Frictional Loss ◽  
Partial Obstruction ◽  
Peripheral Airways ◽  
Volume Curve ◽  
Expiratory Flow

A two-compartment mechanical model of the lungs was constructed with two parallel peripheral and collapsible bronchi in series with one central and collapsible trachea. Maximal expiratory flow-volume (MEFV) curves similar to those obtained in most dogs and in some humans could be produced: a peak followed by a gently sloping plateau ending in a knee, where flow suddenly fell to a much smaller value approaching zero rather slowly over the last 25 to 50% of the expired vital capacity. It was shown that flow before the knee was limited in the trachea, and after the knee it was limited in the bronchi. Two patterns of changes in the configuration of the MEFV curve could be observed. Pattern of changes affecting the central airway, at a given volume, maximal flow during the first part of the expiration (i.e., before the knee) is decreased; the knee occurs at a lower lung volume; the flow at the beginning of the knee is decreased. This pattern was observed with the following interventions: decreased cross-sectional area of the trachea (partial obstruction); decreased axial tension of the trachea; and, increased frictional loss between the trachea and the bronchi. Pattern of changes affecting the airways in the periphery: the knee occurs at a higher lung volume; at a given volume, flow after the knee becomes smaller; the absolute flow at the start of the knee is almost unchanged. This pattern was observed with the following interventions: decreased cross-sectional area of the peripheral airways (partial obstruction); increased frictional loss upstream to the peripheral airways; and, decreased elastic recoil pressure.

Postpneumonectomy airway growth in the ferret

1985 ◽  
Vol 58 (3) ◽  
pp. 1010-1014 ◽  
Author(s):  
J. T. McBride
Keyword(s):  
Lung Volume ◽  
Lung Resection ◽  
Lower Lobe ◽  
Cross Sectional Area ◽  
Left Lower Lobe ◽  
Sectional Area ◽  
Cross Sectional ◽  
Peripheral Airways ◽  
Four Levels ◽  
Conducting Airways

To investigate the participation of the conducting airways in compensatory growth following partial lung resection, bronchial casts of six ferrets having undergone right-sided pneumonectomy at 8 wk of age were compared with those of five sham-operated control animals. At maturity, the left lungs of the postpneumonectomy animals were 65% larger than those of the controls. Central airway cross-sectional areas at 10 specific locations in each cast were 12% larger in the postpneumonectomy animals compared with controls. To characterize the size of more peripheral airways, the size and number of the terminal bronchioles subtended by each airway in each left lower lobe cast were identified so that the fraction of the lobe served by that airway could be estimated. The characteristic cross-sectional areas of airway serving 0.7, 2.2, and 9.5% of the left lower lobe in postpneumonectomy animals were 18, 13, and 13% larger than those of controls, but this difference was statistically significant only at the two more peripheral levels. Although airway areas were larger in postpneumonectomy animals, the ratio of airway cross-sectional area to the 0.67 power of lung volume was 20–26% smaller in operated than in control animals at each of the four levels. Following pneumonectomy in the weanling ferret, central and peripheral conducting airways increase in cross-sectional area to similar degrees, but this airway growth is less than the compensatory increase in lung volume.

scholarly journals Functional effect of longitudinal heterogeneity in constricted airways before and after lung expansion

2012 ◽  
Vol 112 (1) ◽  
pp. 237-245 ◽  
Author(s):  
C. Wongviriyawong ◽  
R. S. Harris ◽  
H. Zheng ◽  
M. Kone ◽  
T. Winkler ◽  
...  
Keyword(s):  
Lung Volume ◽  
Total Lung Capacity ◽  
Cross Sectional Area ◽  
Cylindrical Shape ◽  
Sectional Area ◽  
High Resolution Computed Tomography ◽  
Cross Sectional ◽  
Lung Capacity ◽  
Lung Expansion ◽  
Before And After

Heterogeneity in narrowing among individual airways is an important contributor to airway hyperresponsiveness. This paper investigates the contribution of longitudinal heterogeneity (the variability along the airway in cross-sectional area and shape) to airway resistance ( Raw). We analyzed chest high-resolution computed tomography scans of 8 asthmatic (AS) and 9 nonasthmatic (NA) subjects before and after methacholine (MCh) challenge, and after lung expansion to total lung capacity. In each subject, Raw was calculated for 35 defined central airways with >2 mm diameter. Ignoring the area variability and noncircular shape results in an underestimation of Raw (%Utotal) that was substantial in some airways (∼50%) but generally small (median <6%). The average contribution of the underestimation of Raw caused by longitudinal heterogeneity in the area (%Uarea) to %Utotal was 36%, while the rest was due to the noncircularity of the shape (%Ushape). After MCh challenge, %Uarea increased in AS and NA ( P < 0.05). A lung volume increase to TLC reduced %Utotal and %Uarea in both AS and NA ( P < 0.0001, except for %Utotal in AS with P < 0.01). Only in NA, %Ushape had a significant reduction after increasing lung volume to TLC ( P < 0.005). %Uarea was highly correlated, but not identical to the mean-normalized longitudinal heterogeneity in the cross-sectional area [CV2( A)] and %Ushape to the average eccentricity of the elliptical shape. This study demonstrates that Raw calculated assuming a cylindrical shape and derived from an average area along its length may, in some airways, substantially underestimate Raw. The observed changes in underestimations of Raw with the increase in lung volume to total lung capacity may be consistent with, and contribute in part to, the differences in effects of deep inhalations in airway function between AS and NA subjects.

Pelvic Canal Narrowing Caused by Triple Pelvic Osteotomy in the Dog

1994 ◽  
Vol 07 (03) ◽  
pp. 110-113 ◽  
Author(s):  
D. L. Holmberg ◽  
M. B. Hurtig ◽  
H. R. Sukhiani
Keyword(s):  
Postoperative Complications ◽  
Pelvic Osteotomy ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Canal Width ◽  
Operative Complications ◽  
Post Operative Complications

SummaryDuring a triple pelvic osteotomy, rotation of the free acetabular segment causes the pubic remnant on the acetabulum to rotate into the pelvic canal. The resulting narrowing may cause complications by impingement on the organs within the pelvic canal. Triple pelvic osteotomies were performed on ten cadaver pelves with pubic remnants equal to 0, 25, and 50% of the hemi-pubic length and angles of acetabular rotation of 20, 30, and 40 degrees. All combinations of pubic remnant lengths and angles of acetabular rotation caused a significant reduction in pelvic canal-width and cross-sectional area, when compared to the inact pelvis. Zero, 25, and 50% pubic remnants result in 15, 35, and 50% reductions in pelvic canal width respectively. Overrotation of the acetabulum should be avoided and the pubic remnant on the acetabular segment should be minimized to reduce postoperative complications due to pelvic canal narrowing.When performing triple pelvic osteotomies, the length of the pubic remnant on the acetabular segment and the angle of acetabular rotation both significantly narrow the pelvic canal. To reduce post-operative complications, due to narrowing of the pelvic canal, overrotation of the acetabulum should be avoided and the length of the pubic remnant should be minimized.

DETERMINATION OF THE FUNCTION OF THE ROD’S CROSS-SECTIONAL AREA USING VIBRATION EIGENFREQUENCIES

2020 ◽  
Vol 0 (4) ◽  
pp. 19-24
Author(s):  
I.M. UTYASHEV ◽  
◽  
A.A. AITBAEVA ◽  
A.A. YULMUKHAMETOV ◽  
◽  
...  
Keyword(s):  
Cross Sectional Area ◽  
Variable Cross ◽  
Sectional Area ◽  
Longitudinal Vibrations ◽  
Cross Sectional ◽  
Method Error ◽  
Various Boundary Conditions ◽  
Elastic Fixation ◽  
Crosssectional Area

The paper presents solutions to the direct and inverse problems on longitudinal vibrations of a rod with a variable cross-sectional area. The law of variation of the cross-sectional area is modeled as an exponential function of a polynomial of degree n . The method for reconstructing this function is based on representing the fundamental system of solutions of the direct problem in the form of a Maclaurin series in the variables x and λ. Examples of solutions for various section functions and various boundary conditions are given. It is shown that to recover n unknown coefficients of a polynomial, n eigenvalues are required, and the solution is dual. An unambiguous solution was obtained only for the case of elastic fixation at one of the rod’s ends. The numerical estimation of the method error was made using input data noise. It is shown that the error in finding the variable crosssectional area is less than 1% with the error in the eigenvalues of longitudinal vibrations not exceeding 0.0001.

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