Respiratory impedance measured by forced oscillation technique in young healthy preschool children

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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Impact of lung disease on respiratory impedance in young children with cystic fibrosis

European Respiratory Journal ◽

10.1183/13993003.00156-2015 ◽

2015 ◽

Vol 46 (6) ◽

pp. 1672-1679 ◽

Cited By ~ 12

Author(s):

Kathryn A. Ramsey ◽

Sarath C. Ranganathan ◽

Catherine L. Gangell ◽

Lidija Turkovic ◽

Judy Park ◽

...

Keyword(s):

Cystic Fibrosis ◽

Preschool Children ◽

Lung Disease ◽

Forced Oscillation ◽

Forced Oscillation Technique ◽

Respiratory Resistance ◽

Lung Abnormalities ◽

Respiratory Inflammation ◽

Function Testing ◽

Tomography Scan

This study aimed to evaluate the ability of the forced oscillation technique (FOT) to detect underlying lung disease in preschool children with cystic fibrosis (CF) diagnosed following newborn screening.184 children (aged 3–6 years) with CF underwent lung function testing on 422 occasions using the FOT to assess respiratory resistance and reactance at the time of their annual bronchoalveolar lavage collection and chest computed tomography scan. We examined associations between FOT outcomes and the presence and progression of respiratory inflammation, infection and structural lung disease.Children with CF who had pronounced respiratory disease, including free neutrophil elastase activity, infection with pro-inflammatory pathogens and structural lung abnormalities had similar FOT outcomes to those children without detectable lung disease. In addition, the progression of lung disease over 1 year was not associated with worsening FOT outcomes.We conclude that the forced oscillation technique is relatively insensitive to detect underlying lung disease in preschool children with CF. However, FOT may still be of value in improving our understanding of the physiological changes associated with early CF lung disease.

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Respiratory resistance by end-inspiratory occlusion and forced oscillations in intubated patients

Journal of Applied Physiology ◽

10.1152/jappl.1996.80.4.1105 ◽

1996 ◽

Vol 80 (4) ◽

pp. 1105-1111 ◽

Cited By ~ 12

Author(s):

L. Beydon ◽

P. Malassine ◽

A. M. Lorino ◽

C. Mariette ◽

F. Bonnet ◽

...

Keyword(s):

Forced Oscillation ◽

Forced Oscillations ◽

Forced Oscillation Technique ◽

Respiratory Impedance ◽

Respiratory Resistance ◽

Airway Occlusion ◽

Residual Capacity ◽

Occlusion Technique ◽

Air Compression ◽

Good Agreement

Measurement of respiratory impedance by the forced oscillation technique (FOT) in intubated patients requires corrections for the flow-dependent resistance, inertance, and air compression inside the endotracheal tube (ETT). Recently, we published a method to correct respiratory impedance for the mechanical contribution of the ETT. To validate this correction, we compared the respiratory resistance obtained with this method (Rfo) to the intrinsic (Rmin) and total resistances (RT) measured by the airway-occlusion technique (OCT) in 16 intubated sedated paralyzed ventilated patients. The FOT was applied at functional residual capacity in the 4- to 32-Hz frequency range, whereas the OCT was performed at the end of a normal constant-flow inspiration. Rmin corrected with Rfo measured at 16 and 32 Hz [Rfo(16) = 1.10 x Rmin + 0.10 cmH2O.s.l-1, r = 0.96, P < 0.001; Rfo(32) = 0.93 x Rmin + 0.72 cmH2O.s.l-1, r = 0.97, P < 0.001]. RT corrected with Rfo at 4 Hz [Rfo(4) = 1.11 x RT - 1.48 cmH2O.s.l-1; = 0.92; P < 0.001]. We conclude that the FOT improved by correction for the behavior of the ETT is in good agreement with the OCT in intubated patients.

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