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.

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.

A new method to determine frequency characteristics of the respiratory system

1976 ◽  
Vol 41 (1) ◽  
pp. 101-106 ◽  
Author(s):  
F. J. Landser ◽  
J. Nagles ◽  
M. Demedts ◽  
L. Billiet ◽  
K. P. van de Woestijne
Keyword(s):  
Fourier Analysis ◽  
Respiratory System ◽  
Coefficient Of Variation ◽  
Spontaneous Breathing ◽  
Forced Oscillation ◽  
Forced Oscillation Technique ◽  
Body Plethysmography ◽  
Mouth Pressure ◽  
Loud Speaker ◽  
Good Agreement

A technique is described allowing one to determine simultaneously the resistance and reactance of the total respiratory system for various frequencies. During spontaneous breathing, regularly recurring impulses are produced at the mouth by means of a loud speaker. A Fourier analysis of the mouth pressure and flow signals yields mean resistance and reactance values, over16 s, for all harmonics of 2 Hz up to 30 Hz. The values are in good agreement with those obtained in the absence of breathing and those determined by means of the forced oscillation technique and by body plethysmography. The reproducibility of the measurements is satisfactory (coefficient of variation: 11.6%).

Respiratory mechanics of horses measured by conventional and forced oscillation techniques

1994 ◽  
Vol 76 (6) ◽  
pp. 2467-2472 ◽  
Author(s):  
S. S. Young ◽  
D. Tesarowski
Keyword(s):  
Resonant Frequency ◽  
Respiratory System ◽  
Respiratory Mechanics ◽  
Forced Oscillation ◽  
Dynamic Compliance ◽  
Close Correlation ◽  
Esophageal Pressure ◽  
Forced Oscillation Technique ◽  
Pulmonary Resistance ◽  
Oscillation System

Respiratory mechanics were compared using conventional and forced oscillation techniques in six conscious horses and a mechanical model of the equine respiratory system. The parameters calculated from conventional airflow and esophageal pressure measurements were pulmonary resistance and dynamic compliance. The impedance of the respiratory system was measured at 1, 2, and 3 Hz with the forced oscillation technique, and respiratory system resistance, compliance, inertance, and resonant frequency were calculated. Pulmonary resistance was 1.0 +/- 0.3 cmH2O.l-1.s, and pulmonary dynamic compliance was 2.4 +/- 0.6 l/cmH2O. With the use of the forced oscillation system, respiratory resistance was 1.61 +/- 0.50 cmH2O.l-1.s at 1 Hz, compliance was 0.195 +/- 0.075 l/cmH2O, inertance was 0.026 +/- 0.0095 cmH2O.l-1.s2, and resonant frequency was 2.40 +/- 0.25 Hz. Data collected from a model of the respiratory system showed a close correlation between resistance and compliance measured with the two systems. This study demonstrates that the forced oscillation technique is a useful method for noninvasive measurement of respiratory mechanics in horses.

Optimized estimation of respiratory impedance by signal averaging in the time domain

1992 ◽  
Vol 73 (3) ◽  
pp. 1181-1189 ◽  
Author(s):  
R. Farre ◽  
M. Rotger ◽  
D. Navajas
Keyword(s):  
Time Domain ◽  
Forced Oscillation ◽  
Computing Time ◽  
Forced Oscillation Technique ◽  
Respiratory Impedance ◽  
Signal Averaging ◽  
Low Frequencies ◽  
Time Domain Signal ◽  
On Line ◽  
The Time Domain

The spontaneous breathing of a subject during measurements of respiratory impedance (Zrs) by the forced oscillation technique (FOT) induces errors that result in biased impedance estimates, especially at low frequencies. Although in standard measurements this bias may be avoided by using special impedance estimators, there are two applications of FOT for which such estimators are not useful: when a head generator is used and when measurements are made during intubation. In this paper we describe a data-processing procedure for unbiased impedance estimation for all FOT setups. The proposed estimator (Z) was devised for pseudorandom excitation and is based on time-domain signal averaging before frequency analysis. The performance of estimator Z was first analyzed by computer simulation of a head generator setup and a setup including an endotracheal tube to measure (2–32 Hz) a resistance-inertance-elastance model mimicking Zrs of a healthy subject. Second, Z was assessed during real measurements in 16 healthy subjects. The results obtained in the simulation (e.g., error in elastance was reduced from 15.6% with most conventional estimators to 3.3% with Z in simulation of head generator setup) and in the measurements in subjects (differences of less than 1.6% between Z and a reference) confirmed the theoretical lack of bias of Z and its practical suitability for the different FOT setups. In addition to its applicability in the situations in which no other unbiased estimators are available, estimator Z is also advantageous in most conventional applications of FOT, since it requires much less computing time and thus allows on-line Zrs measurements.

Entraining the natural frequencies of running and breathing in guinea fowl (Numida meleagris)

2001 ◽  
Vol 204 (9) ◽  
pp. 1641-1651 ◽  
Author(s):  
P.N. Nassar ◽  
A.C. Jackson ◽  
D.R. Carrier
Keyword(s):  
Resonant Frequency ◽  
Respiratory System ◽  
Natural Frequencies ◽  
Lung Ventilation ◽  
Guinea Fowl ◽  
Forced Oscillation Technique ◽  
Step Frequency ◽  
Numida Meleagris ◽  
Significant Difference ◽  
Treadmill Locomotion

Lung ventilation of tetrapods that synchronize their locomotory and ventilatory cycles during exercise could be economized if the resonant frequency of the respiratory system matched the animal's preferred step frequency. To test whether animals utilize this strategy, the input impedance of the respiratory system of five anesthetized, supine guinea fowl (Numida meleagris) was measured using a forced oscillation technique. The resonant frequency of the respiratory system was 7.12+/−0.27 Hz (N=5, mean +/− S.E.M.). No statistically significant difference was found between the resonant frequency of the respiratory system and the panting frequency used by guinea fowl at rest (6.67+/−0.16 Hz, N=11) or during treadmill locomotion (6.71+/−0.12 Hz, N=8) or to their preferred step frequency (6.73+/−0.09 Hz, N=7) (means +/− S.E.M.). These observations suggest (i) that, at rest and during exercise, panting guinea fowl maximize flow while expending minimal mechanical effort, and (ii) that natural selection has tuned the natural frequencies of the respiratory and locomotor systems to similar frequencies.

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
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