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.

A modified measurement of respiratory resistance by forced oscillation during normal breathing

1975 ◽  
Vol 39 (2) ◽  
pp. 305-311 ◽  
Author(s):  
D. C. Stanescu ◽  
R. Fesler ◽  
C. Veriter ◽  
A. Fans ◽  
L. Brasseur
Keyword(s):  
Flow Rate ◽  
Respiratory System ◽  
Obstructive Lung Disease ◽  
Forced Oscillation ◽  
Forced Oscillation Technique ◽  
Good Reproducibility ◽  
Respiratory Resistance ◽  
Normal Breathing ◽  
Respiratory Flow ◽  
Mouth Pressure

We have modified the measurements of the resistance of the respiratory system, Rrs, by the forced oscillation technique and we have developed equipment to automatically compute Rrs. Flow rate and mouth pressure are treated by selective averaging filters that remove the interference of the subject's respiratory flow on the imposed oscillations. The filtered mean Rrs represents a weighted ensemble average computer over both inspiration and expiration. This method avoids aberrant Rrs values, decreases the variability, and yields an unbiased mean Rrs. Rrs may be measured during slow or rapid spontaneous breathing, in normals and in obstructive patients, over a range of 3–9 Hz. A good reproducibility of Rrs at several days' interval was demonstrated. Frequency dependence of Rrs was found in patients with obstructive lung disease but not in healthy nonsmokers.

scholarly journals Distinct Mechanical Properties of the Respiratory System Evaluated by Forced Oscillation Technique in Acute Exacerbation of COPD and Acute Decompensated Heart Failure

Diagnostics ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 554
Author(s):  
Silvia Terraneo ◽  
Rocco Francesco Rinaldo ◽  
Giuseppe Francesco Sferrazza Papa ◽  
Fulvia Ribolla ◽  
Carlo Gulotta ◽  
...  
Keyword(s):  
Heart Failure ◽  
Mechanical Properties ◽  
Acute Exacerbation ◽  
Respiratory System ◽  
Forced Oscillation ◽  
Acute Decompensated Heart Failure ◽  
Decompensated Heart Failure ◽  
Forced Oscillation Technique ◽  
Acute Exacerbation Of Copd ◽  
Exacerbation Of Copd

Discriminating between cardiac and pulmonary dyspnea is essential for patients’ management. We investigated the feasibility and ability of forced oscillation techniques (FOT) in distinguishing between acute exacerbation of COPD (AECOPD), and acute decompensated heart failure (ADHF) in a clinical emergency setting. We enrolled 49 patients admitted to the emergency department (ED) for dyspnea and acute respiratory failure for AECOPD, or ADHF, and 11 healthy subjects. All patients were able to perform bedside FOT measurement. Patients with AECOPD showed a significantly higher inspiratory resistance at 5 Hz, Xrs5 (179% of predicted, interquartile range, IQR 94–224 vs. 100 IQR 67–149; p = 0.019), and a higher inspiratory reactance at 5 Hz (151%, IQR 74–231 vs. 57 IQR 49–99; p = 0.005) than patients with ADHF. Moreover, AECOPD showed higher heterogeneity of ventilation (respiratory system resistance difference at 5 and 19 Hz, Rrs5-19: 1.49 cmH2O/(L/s), IQR 1.03–2.16 vs. 0.44 IQR 0.22–0.76; p = 0.030), and a higher percentage of flow limited breaths compared to ADHF (10%, IQR 0–100 vs. 0 IQR 0–12; p = 0.030). FOT, which resulted in a suitable tool to be used in the ED setting, has the ability to identify distinct mechanical properties of the respiratory system in AECOPD and ADHF.

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.

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