Enhanced airway dilation by positive-pressure inflation of the lungs compared with active deep inspiration in patients with asthma

2008 ◽  
Vol 105 (6) ◽  
pp. 1725-1732 ◽  
Author(s):  
Annelies M. Slats ◽  
Kirsten Janssen ◽  
Ronald C. de Jeu ◽  
Dirk T. van der Plas ◽  
Robert Schot ◽  
...  
Keyword(s):  
Forced Oscillation ◽  
Forced Expiratory Volume ◽  
Positive Pressure ◽  
Forced Oscillation Technique ◽  
Deep Inspiration ◽  
Respiratory Resistance ◽  
Airway Wall ◽  
Lung Inflation ◽  
Significant Difference ◽  
Response Group

Deep inspiration temporarily reduces induced airways obstruction in healthy subjects. This bronchodilatory effect of deep inspiration is impaired in asthma. Passive machine-assisted lung inflation may augment bronchodilation compared with an active deep inspiration in patients with asthma by either opening closed airways or by reducing fluid flux across the airway wall during deep inspiration, and thereby increasing the tethering forces on the airway wall. We recruited 24 patients with asthma [18–46 yr old, forced expiratory volume in 1 s (FEV1) > 70% predicted; provocative concentration of methacholine inducing a 20% fall in FEV1 (PC20) < 8 mg/ml], with either an impaired ( n = 12) or an intact ( n = 12) bronchodilatory response to deep inspiration. Two methacholine challenges were performed on separate days. At a 50% increase in respiratory resistance (forced oscillation technique at 8 Hz), the change in resistance by a positive-pressure inflation (computer-driven syringe) or an active deep inspiration was measured in randomized order. The reduction in resistance by positive-pressure inflation was significantly greater than by active deep inspiration in the impaired deep inspiration response group (mean change ± SE: −0.6 ± 0.1 vs. −0.03 ± 0.2 cmH2O·l−1·s, P = 0.002). No significant difference was found between positive-pressure inflation and active deep inspiration in the intact deep inspiration response group (−0.6 ± 0.2 vs. −1.0 ± 0.3 cmH2O·l−1·s, P = 0.18). Positive-pressure inflation of the lungs can significantly enhance deep inspiration-induced bronchodilation in patients with asthma.

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

1991 ◽  
Vol 71 (2) ◽  
pp. 770-776 ◽  
Author(s):  
K. N. Desager ◽  
W. Buhr ◽  
M. Willemen ◽  
H. P. van Bever ◽  
W. de Backer ◽  
...  
Keyword(s):  
Forced Oscillation ◽  
Random Noise ◽  
Measuring System ◽  
Time Interval ◽  
Forced Oscillation Technique ◽  
Significant Difference ◽  
Before And After ◽  
Bias Flow ◽  
Sinusoidal Oscillations ◽  
Ventilatory Lung Function

The forced oscillation technique according to Landser et al. (J. Appl. Physiol. 41:101–106, 1976) was modified for use in infants. Adaptations, including a flexible tube to connect the infant to the measuring system and a bias flow to avoid rebreathing, did not influence impedance values. The linearity of the respiratory system was assessed and confirmed by 1) applying pseudo-random noise oscillations at three different amplitudes to 7 infants and 2) comparing in 12 infants impedance values obtained with pseudo-random noise and with sinusoidal oscillations at 12 and 32 Hz. Intersubject variability, averaged for all frequencies, was 6%. In 17 infants the relative error (+/- SD) between two series of five measurements within a time interval of 15 min was 0.5 +/- 5.7%. No statistically significant difference was found between impedance values before and after repositioning of the infant's head, whereas rotation resulted in a decrease in resistance and no effect on reactance. Our results indicate that the infant-adapted forced pseudo-random noise oscillation technique has the potential to give valuable information about ventilatory lung function in infants.

Laryngeal resistance immediately after panting in control and constricted airways

1985 ◽  
Vol 58 (4) ◽  
pp. 1164-1169 ◽  
Author(s):  
K. Sekizawa ◽  
H. Sasaki ◽  
T. Takishima
Keyword(s):  
Forced Oscillation ◽  
Low Frequency ◽  
Normal Subjects ◽  
Forced Oscillation Technique ◽  
Respiratory Resistance ◽  
Frequency Sound ◽  
Laryngeal Resistance ◽  
Control State

Laryngeal resistance (Rla) in the postpanting interval (PPRla) was examined in five normal subjects in the control state and with methacholine- and histamine-induced bronchoconstriction. Respiratory resistance (Rrs) was measured by the forced oscillation technique at 10 Hz, and Rla was measured by the low-frequency sound method (Sekizawa, K., C. Shindoh, W. Hida, S. Suzuki, et al. J. Appl. Physiol. 55:591–597, 1983). Inspiratory Rrs (IRrs) was lower than expiratory Rrs (ERrs), and Rrs immediately after panting (PPRrs) was not significantly different from IRrs in the three airway conditions. Rla increased with bronchoconstriction and inspiratory Rla (IRla) was lower than expiratory Rla (ERla). PPRla was lower than IRla (P less than 0.01) by an amount corresponding to the decrease in Rrs in the control airway. However, in constricted airways, PPRla was higher than IRla and about the same as ERla. We suggest that the panting maneuver is suitable for minimizing the effect of laryngeal artifact in the control airway, but in the constricted airway the panting maneuver may fail to cause widening of the laryngeal orifice.

scholarly journals Potent bronchoprotective effect of deep inspiration and its absence in asthma

2000 ◽  
Vol 89 (2) ◽  
pp. 711-720 ◽  
Author(s):  
Trisevgeni Kapsali ◽  
Solbert Permutt ◽  
Beth Laube ◽  
Nicola Scichilone ◽  
Alkis Togias
Keyword(s):  
Single Dose ◽  
Healthy Subjects ◽  
Alternative Hypothesis ◽  
Forced Expiratory Volume ◽  
Deep Inspiration ◽  
Healthy Individuals ◽  
Lung Inflation ◽  
Airway Caliber ◽  
Physiologic Function ◽  
Rule Out

In the absence of deep inspirations, healthy individuals develop bronchoconstriction with methacholine inhalation. One hypothesis is that deep inspiration results in bronchodilation. In this study, we tested an alternative hypothesis, that deep inspiration acts as a bronchoprotector. Single-dose methacholine bronchoprovocations were performed after 20 min of deep breath inhibition, in nine healthy subjects and in eight asthmatics, to establish the dose that reduces forced expiratory volume in 1 s by >15%. The provocation was repeated with two and five deep inspirations preceding methacholine. Additional studies were carried out to assess optimization and reproducibility of the protocol and to rule out the possibility that bronchoprotection may result from changes in airway geometry or from differential spasmogen deposition. In healthy subjects, five deep inspirations conferred 85% bronchoprotection. The bronchoprotective effect was reproducible and was not attributable to increased airway caliber or to differential deposition of methacholine. Deep inspirations did not protect the bronchi of asthmatics. We demonstrated that bronchoprotection is a potent physiologic function of lung inflation and established its absence, even in mild asthma. This observation deepens our understanding of airway dysfunction in asthma.

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

2015 ◽  
Vol 46 (6) ◽  
pp. 1672-1679 ◽  
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.

The Reliability of Respiratory Resistance Measured by the Forced Oscillation Technique

1986 ◽  
Vol 71 (s15) ◽  
pp. 8P-9P
Author(s):  
J.E. Neild ◽  
C.H.C. Twort ◽  
S. Chinn ◽  
S. McCormack ◽  
P.G.J. Burney ◽  
...  
Keyword(s):  
Forced Oscillation ◽  
Forced Oscillation Technique ◽  
Respiratory Resistance

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

1996 ◽  
Vol 80 (4) ◽  
pp. 1105-1111 ◽  
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.

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.

The repeatability and validity of respiratory resistance measured by the forced oscillation technique

1989 ◽  
Vol 83 (2) ◽  
pp. 111-118 ◽  
Author(s):  
J.E. Neild ◽  
C.H.C. Twort ◽  
S. Chinn ◽  
S. McCormack ◽  
T.D. Jones ◽  
...  
Keyword(s):  
Forced Oscillation ◽  
Forced Oscillation Technique ◽  
Respiratory Resistance

A modified forced oscillation technique for measurements of respiratory resistance

1977 ◽  
Vol 42 (4) ◽  
pp. 650-655 ◽  
Author(s):  
H. Aronsson ◽  
L. Solymar ◽  
J. Dempsey ◽  
J. Bjure ◽  
T. Olsson ◽  
...  
Keyword(s):  
Forced Oscillation ◽  
Signal To Noise Ratio ◽  
Optimization Technique ◽  
Forced Oscillation Technique ◽  
Respiratory Resistance ◽  
Asthmatic Children ◽  
The Difference ◽  
Resistance Value ◽  
Automated Determination

We present a modification of forced oscillation technique for automated determination of total respiratory resistance during inspiration. The modifications consist of a computerized signal averaging and an optimization technique in the assessment of the resistance value. Thereby a favorable signal-to-noise ratio is obtained, allowing very low superimposed pressure oscillations. The method is validated by comparison with a conventional esophageal balloon method, by estimating added mechanical resistances in healthy subjects and by measuring the effect of bronchodilation in asthmatic children. The coefficient of variation as obtained from day-to-day measurements was about 7%. Mechanical resistances, estimated as the difference in total resistance with and without external resistance, were within 7% of their values determined for the resistances alone. A significant decrease in resistance was obtained in each of the asthmatic children following bronchodilation.

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