scholarly journals Respiratory parameter estimation using forced oscillatory impedance data

1977 ◽  
Vol 43 (2) ◽  
pp. 322-330 ◽  
Author(s):  
M. J. Tsai ◽  
R. L. Pimmel ◽  
E. J. Stiff ◽  
P. A. Bromberg ◽  
R. L. Hamlin
Keyword(s):  
Respiratory Symptoms ◽  
Forced Oscillation ◽  
Respiratory Resistance ◽  
Added Resistance ◽  
Tidal Breathing ◽  
Frequency Dependency ◽  
Respiratory Parameter ◽  
Clinically Normal ◽  
Impedance Data ◽  
Residual Capacity

The frequency dependency of the magnitude and phase angle of total respiratory impedance was measured in apneic dogs at functional residual capacity during forced oscillation by a special electronics unit. Regression analysis of these data yielded estimates of total respiratory resistance (RFO), inertance (IFO), and compliance (CFO). After correcting for the effects of the endotracheal tube, mean control values (+/-SE) of RFO, IFO, and CFO for the clinically normal dogs were 1.30+/-0.10 cmH2O–1–1-s, 0.0114+/-0.0022 cmH2O–1–1-s2, and 0.0306+/-0.0009 1-cm H2O–1, respectively. Estimates obtained with added resistance, a less dense gas, and abdominal weighting were consistent with predicted effects. In four dogs with mild respiratory symptoms, mean RFO was significantly elevated with no change in IFO or CFO. Independent measurements of resistance and compliance during tidal ventilation correlated well with RFO (r=0.87) and CFO (r=0.80), but RFO and CFO were, on the average, 71% of the tidal breathing values. Thus, the method provides precise estimates of RFO, IFO, and CFO, and allows detection of small changes in these parameters.

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.

Respiratory input impedance in anesthetized paralyzed patients

1990 ◽  
Vol 69 (4) ◽  
pp. 1372-1379 ◽  
Author(s):  
D. Navajas ◽  
R. Farre ◽  
J. Canet ◽  
M. Rotger ◽  
J. Sanchis
Keyword(s):  
Mechanical Model ◽  
Forced Oscillation ◽  
Respiratory Resistance ◽  
Frequency Range ◽  
Entire Frequency Range ◽  
Peripheral Airways ◽  
Distal Branch ◽  
Low Amplitude ◽  
Gas Compressibility ◽  
Central Airway

Respiratory impedance (Zrs) was measured between 0.25 and 32 Hz in seven anesthetized and paralyzed patients by applying forced oscillation of low amplitude at the inlet of the endotracheal tube. Effective respiratory resistance (Rrs; in cmH2O.l-1.s) fell sharply from 6.2 +/- 2.1 (SD) at 0.25 Hz to 2.3 +/- 0.6 at 2 Hz. From then on, Rrs decreased slightly with frequency down to 1.5 +/- 0.5 at 32 Hz. Respiratory reactance (Xrs; in cmH2O.l-1.s) was -22.2 +/- 5.9 at 0.25 Hz and reached zero at approximately 14 Hz and 2.3 +/- 0.8 at 32 Hz. Effective respiratory elastance (Ers = -2pi x frequency x Xrs; in cmH2O/1) was 34.8 +/- 9.2 at 0.25 Hz and increased markedly with frequency up to 44.2 +/- 8.6 at 2 Hz. We interpreted Zrs data in terms of a T network mechanical model. We represented the proximal branch by central airway resistance and inertance. The shunt pathway accounted for bronchial distensibility and alveolar gas compressibility. The distal branch included a Newtonian resistance component for tissues and peripheral airways and a viscoelastic component for tissues. When the viscoelastic component was represented by a Kelvin body as in the model of Bates et al. (J. Appl. Physiol. 61: 873-880, 1986), a good fit was obtained over the entire frequency range, and reasonable values of parameters were estimated. The strong frequency dependence of Rrs and Ers observed below 2 Hz in our anesthetized paralyzed patients could be mainly interpreted in terms of tissue viscoelasticity. Nevertheless, the high Ers we found with low volume excursions suggests that tissues also exhibit plasticlike properties.

Effects of body position change on thoracoabdominal motion

1978 ◽  
Vol 45 (4) ◽  
pp. 581-589 ◽  
Author(s):  
V. P. Vellody ◽  
M. Nassery ◽  
W. S. Druz ◽  
J. T. Sharp
Keyword(s):  
Supine Position ◽  
Muscle Force ◽  
Body Position ◽  
Tidal Breathing ◽  
Position Change ◽  
Rib Cage ◽  
Inspiratory Muscles ◽  
Residual Capacity ◽  
Lateral Decubitus ◽  
Local Compliance

With a linearized respiratory magnetometer, measurements of anteroposterior and lateral diameters of both the rib cage and the abdomen were made at functional residual capacity and continuously during tidal breathing. Twenty-five subjects with normal respiratory systems were studied in the sitting, supine, lateral decubitus, and prone body positions. When subjects changed from sitting to supine position anteroposterior diameters of both rib cage and abdomen decreased while their lateral diameters increased. Both anteroposterior and lateral tidal excursions of the rib cage decreased; those of the abdomen increased. When subjects turned from supine to lateral decubitus position both anteroposterior diameters increased and the lateral diameters decreased. This was associated with an increase in both lateral excursions and a decrease in the abdominal anteroposterior excursions. Diameters and tidal excursions in the prone position resembled those in the supine position. Diameter changes could be explained by gravitational effects. Differences in tidal excursions accompanying body position change were probably related to 1) differences in the distribution of respiratory muscle force, 2) differences in the activity or mechanical advantage of various inspiratory muscles, and 3) local compliance changes in parts of the rib cage and abdomen.

Forced oscillation technique in veterans with preserved spirometry and chronic respiratory symptoms

2019 ◽  
Vol 260 ◽  
pp. 8-16 ◽  
Author(s):  
Ryan P. Butzko ◽  
Anays M. Sotolongo ◽  
Drew A. Helmer ◽  
Jacquelyn C. Klein-Adams ◽  
Omowunmi Y. Osinubi ◽  
...  
Keyword(s):  
Respiratory Symptoms ◽  
Forced Oscillation ◽  
Forced Oscillation Technique

scholarly journals Tidal airway closure in asthma and COPD

2016 ◽  
Vol 83 (1-2) ◽  
Author(s):  
Claudio Tantucci ◽  
Laura Pini
Keyword(s):  
Stress And Strain ◽  
Small Airways ◽  
Airway Closure ◽  
Functional Tests ◽  
Tidal Breathing ◽  
Copd Patients ◽  
Ventilation Heterogeneity ◽  
Residual Capacity ◽  
Dangerous Condition ◽  
Sequential Measurements

<span style="font-family: 'Times','serif'; font-size: 12pt; mso-ansi-language: EN-US; mso-fareast-font-family: Times; mso-bidi-font-family: 'Times New Roman'; mso-fareast-language: IT; mso-bidi-language: AR-SA;" lang="EN-US">Functional closure of small airways can occur during tidal breathing above functional residual capacity (FRC) both in asthma and COPD patients, especially during exacerbations. Such event has several noxious consequences on gas exchange, airway hyperresponsiveness and mechanical stress and strain within lung tissue and airway wall, mostly due to increase in ventilation heterogeneity. The availability of simple functional tests based on sequential measurements of lung volumes (i.e.: FRC), by plethysmography and dilutional techniques may reveal and monitor easily tidal airway closure that can be and should be treated with the aim of abolishing or at least reducing this dangerous condition.</span>

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.

Respiratory movements of the vocal cords

1983 ◽  
Vol 54 (5) ◽  
pp. 1269-1276 ◽  
Author(s):  
T. Brancatisano ◽  
P. W. Collett ◽  
L. A. Engel
Keyword(s):  
Lung Volume ◽  
Respiratory Control ◽  
Respiratory Muscles ◽  
Normal Subjects ◽  
Tight Coupling ◽  
Tidal Breathing ◽  
Vocal Cords ◽  
Residual Capacity ◽  
The Relationship ◽  
Respiratory Movements

We examined the movements of the vocal cords during tidal breathing, panting, and large changes in lung volume in 12 normal subjects. The glottis was observed with a fiber-optic bronchoscope, and the glottic image was recorded together with flow, volume, and a time marker onto videotape. Phasic respiratory swings in glottic width (dg) and glottic area (Ag) were reproducible in all subjects but differed substantially between subjects. In the group as a whole dg and Ag increased during inspiration to 10.1 +/- 5.6 mm and 126 +/- 8 mm2 (mean +/- SE), respectively, whereas during expiration the lowest values were 5.7 +/- 0.5 mm and 70 +/- 7 mm2, respectively. These extreme dimensions corresponded closely to the midtidal volume points in the respiratory cycle. Glottic width during vital capacity (VC) expirations was nearly 30% greater at a flow of 1.2 l/s than at 0.5 l/s, but the relationship between dg and lung volume differed between subjects. When swings in dg were minimized by panting, there was no difference in dg between functional residual capacity (FRC) and a volume corresponding to midinspiratory capacity. However, tidal breathing at this lung volume was associated with a 20% decrease in dg compared with breathing at FRC. Our observations indicate a tight coupling between the pattern of glottic movement and the respiratory volume cycle. The results suggest that during voluntary respiratory maneuvers both intrinsic laryngeal and respiratory muscles are recruited, participating as effector organs in ventilatory and respiratory control.

Estimating central and peripheral respiratory resistance

1978 ◽  
Vol 45 (3) ◽  
pp. 375-380 ◽  
Author(s):  
R. L. Pimmel ◽  
M. J. Tsai ◽  
D. C. Winter ◽  
P. A. Bromberg
Keyword(s):  
Regression Equations ◽  
Respiratory Resistance ◽  
Added Resistance ◽  
Frequency Range ◽  
External Resistance ◽  
Control Data ◽  
Mean Values ◽  
External Resistor ◽  
The Mean ◽  
Control State

An analytic approach for fractionating total respiratory resistance into central (Rc) and peripheral (Rp) components is presented. In the analysis, linear regression equations relating the logarithm of the measured total resistance to the logarithm of frequency are derived for data spanning the frequency range 1–16 Hz. The computed slope and intercept are used to obtain estimates of the fraction of the resistance in the periphery (Fp) and of Rp and Rc. Data from anesthetized, closed-chested dogs in a control state and with an external resistor (1.37 cmH2O.1–1.s) were used to test the approach. Mean values +/- SE's for control data were: Fp = 0.400 +/- 0.039, Rp = 1.37 +/- 0.16 cm H2O.1–1.s, and Rc = 1.98 +/- 0.10 cmH2O.1–1.s. Mean values of Rp obtained with and without added resistance were not significantly different (P less than 0.1). The increase in the mean values of Rc represented 85% of the value of the added resistance but was significantly different from the known value of the external resistance (P less than 0.05). These data suggest that it may be possible to fractionate total respiratory resistance into central and peripheral components using the frequency dependence of forced oscillatory resistance.

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