Influence of upper airway shunt on total respiratory impedance in infants

1999 ◽  
Vol 87 (3) ◽  
pp. 902-909 ◽  
Author(s):  
K. N. Desager ◽  
M. Cauberghs ◽  
J. Naudts ◽  
K. P. van de Woestijne
Keyword(s):  
Respiratory System ◽  
Airway Resistance ◽  
Oscillatory Flow ◽  
Forced Oscillation ◽  
Upper Airway ◽  
Conventional Technique ◽  
Forced Oscillation Technique ◽  
Respiratory Impedance ◽  
Airway Wall ◽  
Shunt Impedance

When input impedance is determined by means of the forced oscillation technique, part of the oscillatory flow measured at the mouth is lost in the motion of the upper airway wall acting as a shunt. This is avoided by applying the oscillations around the subject’s head (head generator) rather than at the mouth (conventional technique). In seven wheezing infants, we compared both techniques to estimate the importance of the upper airway wall shunt impedance (Zuaw) for the interpretation of the conventional technique results. Computation of Zuaw required, in addition, estimation of nasal impedance values, which were drawn from previous measurements (K. N. Desager, M. Willemen, H. P. Van Bever, W. De Backer, and P. A. Vermeire. Pediatr. Pulmonol. 11: 1–7, 1991). Upper airway resistance and reactance at 12 Hz ranged from 40 to 120 and from 0 to −150 hPa ⋅ l−1 ⋅ s, respectively. Varying nasal impedance within the range observed in infants did not result in major changes in the estimates of Zuaw or lung impedance (Zl), the impedance of the respiratory system in parallel with Zuaw. The conventional technique underestimated Zl, depending on the value of Zuaw. The head generator technique slightly overestimated Zl, probably because the pressure gradient across the upper airway was not completely suppressed. Because of the need to enclose the head in a box (which is not required with the conventional technique), the head generator technique is difficult to perform in infants.

Resistance and reactance of the excised human larynx, trachea, and main bronchi

1987 ◽  
Vol 63 (5) ◽  
pp. 1788-1795 ◽  
Author(s):  
T. X. Jiang ◽  
M. Cauberghs ◽  
K. P. Van de Woestijne
Keyword(s):  
Steady Flow ◽  
Airway Resistance ◽  
Oscillatory Flow ◽  
Forced Oscillation ◽  
Upper Airway ◽  
Forced Oscillation Technique ◽  
Vocal Cords ◽  
Respiratory Flow ◽  
Human Larynx ◽  
Before And After

We investigated the impedance of excised preparations of the human larynx before and after resection of the vocal cords and of the trachea whether or not in connection with the main bronchi for steady (75–700 ml.s-1) and oscillatory flows (4–64 Hz). To simulate the influence of respiratory flow on oscillatory resistance (Rosc), oscillatory and steady flow were superimposed. This resulted in a marked increase of Rosc, dependent on the value of steady flow, a change of the frequency dependence of Rosc, and a decrease of the reactance. The latter effects were particularly pronounced in the preparations of the larynx, especially with a narrow glottis opening. The influence of steady flow on oscillatory resistances is probably the expression of interactions of steady and oscillatory flow regimes in the larynx. Similar but less pronounced interactions are also met in the trachea. These effects lead to a systematic overestimation of upper airway resistance when measured during spontaneous breathing by means of a forced oscillation technique.

Measurement of total respiratory impedance in calves by the forced oscillation technique

1988 ◽  
Vol 64 (5) ◽  
pp. 1786-1791 ◽  
Author(s):  
P. Gustin ◽  
A. R. Dhem ◽  
F. Lomba ◽  
P. Lekeux ◽  
K. P. Van de Woestijne ◽  
...  
Keyword(s):  
Resonant Frequency ◽  
Fourier Analysis ◽  
Respiratory System ◽  
Pressure Wave ◽  
Forced Oscillation ◽  
Forced Oscillation Technique ◽  
Respiratory Impedance ◽  
Upper Airways ◽  
Low Frequencies ◽  
Spontaneously Breathing

We have determined the resistance (Rrs) and the reactance (Xrs) of the total respiratory system in unsedated spontaneously breathing calves at various frequencies. A pseudorandom noise pressure wave was produced at the nostrils of the animals by means of a loudspeaker adapted to the nose by a tightly fitting mask. A Fourier analysis of the pressure in the nostrils and flow signals yielded mean Rrs and Xrs, over 16 s, at frequencies of 2–26 Hz. A good correlation was found between values of pulmonary resistances measured by the isovolume method at the respiratory frequency of animals and values obtained at a frequency of 6 Hz by use of our technique. The linearity of the respiratory system, the reproducibility of the technique, and the effects of upper airways on results have been studied. In healthy calves, Rrs increases with frequency. Mean resonant frequency is 7.5 Hz. Bronchospasm was induced in six calves by administration of intravenous organophosphates. Rrs tended to decrease with increasing frequency. Resonant frequency exceeded 26 Hz. All parameters returned to initial values after administration of atropine. In healthy calves, atropine produces a decrease in Rrs, especially at low frequencies. Values of resonant frequency are not modified.

Mechanical properties of the upper airway

1983 ◽  
Vol 55 (2) ◽  
pp. 335-342 ◽  
Author(s):  
M. Cauberghs ◽  
K. P. Van de Woestijne
Keyword(s):  
Mechanical Properties ◽  
Lung Disease ◽  
Frequency Dependence ◽  
Respiratory System ◽  
Obstructive Lung Disease ◽  
Forced Oscillation ◽  
Valsalva Maneuver ◽  
Upper Airway ◽  
Forced Oscillations ◽  
Forced Oscillation Technique

The series and shunt components of the impedance of the upper airway (Zuaw) were evaluated from measurements obtained during a Valsalva maneuver by means of a modified forced oscillation technique. When the cheeks are supported, the upper airway can be represented by a single distributed transmission line. The homogeneity of this line was confirmed by measuring separately Zuaw and the impedance of the mouth. Correction of the impedance of the respiratory system, determined by means of the forced oscillations technique, for the shunt properties of Zuaw results in some modifications of the frequency dependence of resistance (Rrs) in healthy adults and in marked changes of the absolute values of Rrs in children and in patients with obstructive lung disease.

Effect of upper airway shunt and series properties on respiratory impedance measurements

1989 ◽  
Vol 66 (5) ◽  
pp. 2274-2279 ◽  
Author(s):  
M. Cauberghs ◽  
K. P. Van de Woestijne
Keyword(s):  
Airway Obstruction ◽  
Valsalva Maneuver ◽  
Upper Airway ◽  
Conventional Technique ◽  
Healthy Adults ◽  
Forced Oscillation Technique ◽  
Respiratory Impedance ◽  
Pronounced Increase ◽  
Adults And Children ◽  
Severe Airway Obstruction

Because of the contradictory statements published about the influence of the shunt properties of the upper airway on the measurements of the respiratory impedence by means of the forced oscillation technique, this influence has been reevaluated. In healthy adults and children and in patients with obstructive lung disease, the total respiratory impedance was measured by applying oscillations at the mouth (conventional technique) or around the head (head generator technique), with the cheeks either supported by the hands or not. In healthy adults the two techniques (conventional cheeks supported and head generator) yield similar results for respiratory resistance (Rrs) and a more pronounced increase of respiratory reactance (Xrs) with frequency with the head generator. In children and in patients with moderate airway obstruction, the negative frequency dependence of Rrs observed with the conventional technique tends to disappear with the head generator. This is not observed in patients with severe airway obstruction. The differences between the two techniques can be explained by the influence of the shunt impedance of the upper airway on Rrs and Xrs. Correction for this influence by subtracting the impedance measured during a Valsalva maneuver is not satisfactory, since the Valsalva maneuver itself modifies the upper airway shunt. The head generator technique reduces the influence of the upper airway shunt but does not suppress it altogether; the residual error is small, however.

Contribution of large airway to the input impedance of the respiratory system

1991 ◽  
Vol 70 (2) ◽  
pp. 650-657 ◽  
Author(s):  
J. P. Teeter ◽  
G. M. Saidel ◽  
J. M. Fouke
Keyword(s):  
Respiratory System ◽  
Upper Airway ◽  
Impedance Spectrum ◽  
Lung Model ◽  
Forced Oscillation Technique ◽  
Respiratory Impedance ◽  
Acoustic Reflection ◽  
Large Airway ◽  
Before And After ◽  
Airway Opening

To evaluate the contribution of the large airway to total respiratory impedance, we develop a one-dimensional model of pressure and flow in these airways by coupling conservation of mass and momentum equations with the geometric information obtained by the acoustic reflection technique. We use this model to calculate the impedance of the respiratory system distal to the carina from impedance data estimated at the airway opening by the forced oscillation technique. Simulations show that the real part of the impedance distal to the carina is uniformly decreased from the impedance at the airway opening, indicating a resistive loss, while the imaginary part is increased as a function of frequency. We estimate parameter values for a six-parameter two-compartment lung model and for a three-parameter reduction of this model before and after the application of the upper airway data to the impedance spectrum. Although compliance terms seem to be minimally affected by the manipulation of the data, resistance and inertance terms are influenced in a fashion that suggests that the resistive contribution of the upper airway to total respiratory impedance is significant. Furthermore it appears that the elastic nature of the walls of the upper airway also impact on estimates of total respiratory impedance at the airway opening.

Fluctuations and determinism of respiratory impedance in asthma and chronic obstructive pulmonary disease

2010 ◽  
Vol 109 (6) ◽  
pp. 1582-1591 ◽  
Author(s):  
Michael Muskulus ◽  
Annelies M. Slats ◽  
Peter J. Sterk ◽  
Sjoerd Verduyn-Lunel
Keyword(s):  
Time Series ◽  
Power Law ◽  
Respiratory System ◽  
Single Frequency ◽  
Fluctuation Analysis ◽  
High Temporal Resolution ◽  
Deterministic System ◽  
Forced Oscillation Technique ◽  
Respiratory Impedance ◽  
Wasserstein Distances

Asthma and COPD are chronic respiratory diseases that fluctuate widely with regard to clinical symptoms and airway obstruction, complicating treatment and prediction of exacerbations. Time series of respiratory impedance obtained by the forced oscillation technique are a convenient tool to study the respiratory system with high temporal resolution. In previous studies it was suggested that power-law-like fluctuations exist also in the healthy lung and that respiratory system impedance variability differs in asthma. In this study we elucidate such differences in a population of well-characterized subjects with asthma ( n = 13, GINA 1+2), COPD ( n = 12, GOLD I+II), and controls ( n = 10) from time series at single frequency (12 min, f = 8 Hz). Maximum likelihood estimation did not rule out power-law behavior, accepting the null hypothesis in 17/35 cases ( P > 0.05) and with significant differences in exponents for COPD ( P < 0.03). Detrended fluctuation analysis exhibited scaling exponents close to 0.5, indicating few correlations, with no differences between groups ( P > 0.14). In a second approach, we considered asthma and COPD as dynamic diseases, corresponding to changes of unknown parameters in a deterministic system. The similarity in shape between the combined probability distributions of normalized resistance and reactance was quantified by Wasserstein distances and reliably distinguished the two diseases (cross-validated predictive accuracy 0.80; sensitivity 0.83, specificity 0.77 for COPD). Wasserstein distances between 3+3 dimensional phase space reconstructions resulted in marginally better classification (accuracy 0.84, sensitivity 0.83, specificity 0.85). These latter findings suggest that the dynamics of respiratory impedance contain valuable information for the diagnosis and monitoring of patients with asthma and COPD, whereas the value of the stochastic approach is not clear presently.

Reference values for respiratory impedance measured by the forced oscillation technique in adult men and women

2018 ◽  
Vol 12 (6) ◽  
pp. 2126-2135 ◽  
Author(s):  
Fernando Carlos Vetromille Ribeiro ◽  
Agnaldo José Lopes ◽  
Pedro Lopes de Melo
Keyword(s):  
Reference Values ◽  
Forced Oscillation ◽  
Forced Oscillation Technique ◽  
Respiratory Impedance ◽  
Men And Women ◽  
Adult Men

Flow Resistance in Tracheotomy Tubes

1973 ◽  
Vol 82 (6) ◽  
pp. 827-830 ◽  
Author(s):  
John Cavo ◽  
Joseph H. Ogura ◽  
Donald G. Sessions ◽  
J. Roger Nelson
Keyword(s):  
Laminar Flow ◽  
Respiratory System ◽  
Flow Resistance ◽  
Airway Resistance ◽  
Upper Airway ◽  
Plastic Tube ◽  
Flow Rates ◽  
Pressure Drops ◽  
Adult Human

The role of the upper airway (the breathing passage above the trachea) in maintaining the normal junction of the respiratory system has been suggested by previous investigators. During a tracheotomy the upper airway is by-passed by a prosthetic metal or plastic tube which is placed into the trachea through the neck. In order to determine which, among the most commonly used tracheotomy tubes, most closely simulate the flow resistance of the adult human upper airway, a series of varying flow rates were passed through different sized tubes. Pressure drops were recorded and resistance values were thereby determined. Our data was compared with previously determined values for flow resistance of the adult human upper airway. Resistance related to turbulent and laminar flow was considered. On the basis of our data we have suggested that large caliber tracheotomy tubes be used in adult patients in whom the prolonged need for a tracheotomy is anticipated.

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