Spatial and Temporal Variation of Secondary Flow During Oscillatory Flow in Model Human Central Airways

1999 ◽  
Vol 121 (6) ◽  
pp. 565-573 ◽  
Author(s):  
G. Tanaka ◽  
T. Ogata ◽  
K. Oka ◽  
K. Tanishita
Keyword(s):  
Secondary Flow ◽  
Oscillatory Flow ◽  
Main Bronchus ◽  
Spatial And Temporal Variation ◽  
High Frequency Oscillation ◽  
Laser Doppler Velocimeter ◽  
Left Bronchus ◽  
Secondary Velocity ◽  
Human Airways ◽  
The Right

Axial and secondary velocity profiles were measured in a model human central airway to clarify the oscillatory flow structure during high-frequency oscillation. We used a rigid model of human airways consisting of asymmetrical bifurcations up to third generation. Velocities in each branch of the bifurcations were measured by two-color laser-Doppler velocimeter. The secondary velocity magnitudes and the deflection of axial velocity were dependent not only on the branching angle and curvature ratio of each bifurcation, but also strongly depended on the shape of the path generated by the cascade of branches. Secondary flow velocities were higher in the left bronchus than in the right bronchus. This spatial variation of secondary flow was well correlated with differing gas transport rates between the left and right main bronchus.

Gas Dispersion in a Model Pulmonary Bifurcation During Oscillatory Flow

1997 ◽  
Vol 119 (3) ◽  
pp. 309-316 ◽  
Author(s):  
M. Nishida ◽  
Y. Inaba ◽  
K. Tanishita
Keyword(s):  
Velocity Profile ◽  
Axial Velocity ◽  
Oscillatory Flow ◽  
Gas Transport ◽  
Main Bronchus ◽  
High Frequency Oscillation ◽  
Laser Doppler Velocimeter ◽  
Straight Tube ◽  
Gas Dispersion ◽  
Axial Velocity Profile

In order to clarify the gas transport process in high-frequency oscillation, we measured the axial velocity profile and the axial effective diffusivity in a single asymmetric bifurcating tube, based on the Horsfield airway model, with sinusoidally oscillatory flow. The axial velocity profiles were measured using a laser-Doppler velocimeter, and the effective diffusivities were evaluated using a simple bolus injection method. The axial velocity profile was found to be nonuniform, promoting axial gas dispersion by the spread of the concentration profile and lateral mixing. The geometric asymmetry of the bifurcation was responsible for the difference in gas transport between the main bronchi. The axial gas transport in the left main bronchus was 2.3 times as large as that of the straight tube, whereas the gas transport in the right main bronchus was slightly larger than that of the straight tube. Thus localized variation in gas transport characterized the heterogeneous respiratory function of the lung.

scholarly journals “Blind” Placement of Plastic Left Double-Lumen Tubes

1995 ◽  
Vol 23 (5) ◽  
pp. 583-586 ◽  
Author(s):  
J. B. Brodsky ◽  
A. Macario ◽  
W. B. Cannon ◽  
J. B. D. Mark
Keyword(s):  
Main Bronchus ◽  
Intraoperative Complications ◽  
Clinical Signs ◽  
Prospective Analysis ◽  
Double Lumen ◽  
Left Bronchus ◽  
The Right

A prospective analysis of placement of left-sided plastic double-lumen tubes in 100 patients is presented. Intubation of the left bronchus was successfully accomplished using only auscultation and clinical signs (“blind” placement) in 91 patients. Double-lumen tubes were positioned in less than five minutes in 84 patients. The most common problem encountered (30%) was initial intubation of the right main bronchus. Seven of these patients required bronchoscopic assistance to guide the tube into the left bronchus. There were four minor intraoperative complications due to DLT malposition that were recognized and corrected by withdrawing the tube slightly back in the bronchus. The plastic double-lumen tubes functioned properly during the procedure in all 100 patients.

scholarly journals Prenatal Observation of Fetal Trachea and Bilateral Bronchi using Ultrasonography

2014 ◽  
Vol 8 (4) ◽  
pp. 353-361
Author(s):  
Showa Aoki
Keyword(s):  
Main Bronchus ◽  
Color Doppler ◽  
Three Dimensional ◽  
Azygos Vein ◽  
3D Ultrasound ◽  
Ascending Aorta ◽  
Left Bronchus ◽  
Lobar Bronchus ◽  
The Right ◽  
Flow Waveforms

ABSTRACT The fetal airway tract can be observed using the planes of view in cardiac screening. In three-vessel-tracheal view, the crosssection of the trachea is identified adjacent to the right-posterior side of the middle transverse aorta. In three-vessel view, the cross-section of the right bronchus is observed adjacent to the right side of the ascending aorta. In aortic and ductal arch views, the short axis of the left bronchus is confirmed inward of the arch. In oblique three-vessel view, the right bronchus is seen on top of the ascending aorta coursing toward the azygos vein. To exclude the vessels, absence of blood flow signals in the trachea and bronchi should be reconfirmed by using pulsed and color Doppler imagings. In the whole ‘Y-shaped’ image, the right main bronchus depicts the more linear extension from the trachea than the left bronchus and the first lobar bronchus that branches near the carina to the right upper lobe. Segmental bronchi also can be depicted in both bilateral bronchi. Several new modalities, including three-dimensional (3D) ultrasound, simultaneous visualization of the fetal trachea and esophagus, and fluid flow waveforms in the fetal airway tract, makes feasible detailed prenatal assessment, prediction of neonatal respiratory condition, and most especially identification of anatomical deformity and pathologic entities. How to cite this article Aoki S. Prenatal Observation of Fetal Trachea and Bilateral Bronchi using Ultrasonography. Donald School J Ultrasound Obstet Gynecol 2014;8(4):353-361.

Secondary Velocity Fields in the Conducting Airways of the Human Lung

2007 ◽  
Vol 129 (5) ◽  
pp. 722-732 ◽  
Author(s):  
Frank E. Fresconi ◽  
Ajay K. Prasad
Keyword(s):  
Secondary Flow ◽  
Oscillatory Flow ◽  
Flow Direction ◽  
Flow Fields ◽  
Velocity Fields ◽  
Secondary Flows ◽  
Womersley Number ◽  
Dean Number ◽  
Steady Streaming ◽  
Secondary Velocity

An understanding of flow and dispersion in the human respiratory airways is necessary to assess the toxicological impact of inhaled particulate matter as well as to optimize the design of inhalable pharmaceutical aerosols and their delivery systems. Secondary flows affect dispersion in the lung by mixing solute in the lumen cross section. The goal of this study is to measure and interpret these secondary velocity fields using in vitro lung models. Particle image velocimetry experiments were conducted in a three-generational, anatomically accurate model of the conducting region of the lung. Inspiration and expiration flows were examined under steady and oscillatory flow conditions. Results illustrate secondary flow fields as a function of flow direction, Reynolds number, axial location with respect to the bifurcation junction, generation, branch, phase in the oscillatory cycle, and Womersley number. Critical Dean number for the formation of secondary vortices in the airways, as well as the strength and development length of secondary flow, is characterized. The normalized secondary velocity magnitude was similar on inspiration and expiration and did not vary appreciably with generation or branch. Oscillatory flow fields were not significantly different from corresponding steady flow fields up to a Womersley number of 1 and no instabilities related to shear were detected on flow reversal. These observations were qualitatively interpreted with respect to the simple streaming, augmented dispersion, and steady streaming convective dispersion mechanisms.

scholarly journals Mucosal Changes in the Trachea and Main Bronchi of Newborn Infants after Nasotracheal Intubation

1975 ◽  
Vol 3 (3) ◽  
pp. 209-217 ◽  
Author(s):  
G. C. Fisk ◽  
W. de C. Baker
Keyword(s):  
Endotracheal Tube ◽  
Main Bronchus ◽  
Squamous Metaplasia ◽  
Nasotracheal Intubation ◽  
Newborn Infants ◽  
Respiratory Epithelium ◽  
Lower Trachea ◽  
Nasotracheal Tube ◽  
Mucosal Changes ◽  
The Right

Permanent sequelae of nasotracheal intubation are uncommon, but acute ulceration and squamous metaplasia occur. Histological sections from the trachea and main bronchi were examined in 12 infants. A nasotracheal tube had been inserted during the first two weeks of life of these infants and had been in place for more than one week. In four cases the patient died some time (7 to 108 days) after extubation. Similar sections from patients who were not intubated, intubated only for attempted resuscitation, or intubated for several hours were studied for comparison. The sections were classified according to the degree of mucosal loss and metaplasia, and the extent of the lesions was estimated. Squamous change was seen in most sections from all 12 patients with the exception of one who died 57 days after extubation. Some respiratory epithelium was seen in all patients. In the eight patients who died while intubated, the changes were more marked in the right main bronchus than the left in seven, and more marked in the lower trachea than the upper in five. In the two patients intubated for several hours, in addition to mucosal loss, early metaplasia was seen. It is suggested that mucosal loss is replaced by the squamous metaplasia, and that trauma caused by suction catheters in the lower trachea and right main bronchus is more extensive than that due to the endotracheal tube itself.

scholarly journals Incidence Angle and Pitch-Chord Effects on Secondary Flows Downstream of a Turbine Cascade

1992 ◽  
Author(s):  
A. Perdichizzi ◽  
V. Dossena
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Incidence Angle ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Pressure Probe ◽  
Turbine Cascade ◽  
Oil Flow ◽  
Secondary Velocity ◽  
Secondary Flow Field

This paper describes the results of an experimental investigation of the three-dimensional flow downstream of a linear turbine cascade at off-design conditions. The tests have been carried out for five incidence angles from −60 to +35 degrees, and for three pitch-chord ratios: s/c = 0.58,0.73,0.87. Data include blade pressure distributions, oil flow visualizations, and pressure probe measurements. The secondary flow field has been obtained by traversing a miniature five hole probe in a plane located at 50% of an axial chord downstream of the trailing edge. The distributions of local energy loss coefficients, together with vorticity and secondary velocity plots show in detail how much the secondary flow field is modified both by incidence and cascade solidity variations. The level of secondary vorticity and the intensity of the crossflow at the endwall have been found to be strictly related to the blade loading occurring in the blade entrance region. Heavy changes occur in the spanwise distributions of the pitch averaged loss and of the deviation angle, when incidence or pitch-chord ratio is varied.

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