<i>Oscillation Mechanics of Lungs and Chest in Man</i>

DuBois, Arthur B.; Brody, Alfred W.; Lewis, David H.; Burgess, B. Franklin

doi:10.1152/jappl.1956.8.6.587

Cited by 739 publications

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“…The term C g denotes the alveolar gas compression compliance based on the Dubois six-element terminal airway model. 32 Also based on the Dubois model, R t , I t , and C t denote the terminal tissue resistance, inertia, and compliance, respectively.…”

Section: Theory a Airway Acousticsmentioning

confidence: 99%

A comprehensive computational model of sound transmission through the porcine lung

Dai

Peng

Henry

et al. 2014

The Journal of the Acoustical Society of America

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A comprehensive computational simulation model of sound transmission through the porcine lung is introduced and experimentally evaluated. This "subject-specific" model utilizes parenchymal and major airway geometry derived from x-ray CT images. The lung parenchyma is modeled as a poroviscoelastic material using Biot theory. A finite element (FE) mesh of the lung that includes airway detail is created and used in COMSOL FE software to simulate the vibroacoustic response of the lung to sound input at the trachea. The FE simulation model is validated by comparing simulation results to experimental measurements using scanning laser Doppler vibrometry on the surface of an excised, preserved lung. The FE model can also be used to calculate and visualize vibroacoustic pressure and motion inside the lung and its airways caused by the acoustic input. The effect of diffuse lung fibrosis and of a local tumor on the lung acoustic response is simulated and visualized using the FE model. In the future, this type of visualization can be compared and matched with experimentally obtained elastographic images to better quantify regional lung material properties to noninvasively diagnose and stage disease and response to treatment.

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Section: Theory a Airway Acousticsmentioning

confidence: 99%

A comprehensive computational model of sound transmission through the porcine lung

Dai

Peng

Henry

et al. 2014

The Journal of the Acoustical Society of America

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“…Therefore, an increased resistance at 5 Hz reflects an increase in total respiratory resistance, which suggests airway obstruction such as that found in patients with COPD, whereas a resistance increase at 20 Hz reflects more specifically increased central airway resistance, such as that found in patients with CAO, due to various causes. 13 This technique was introduced in 1956 to measure respiratory resistance and respiratory reactance in humans, 14 and has been employed to assess peripheral airway obstruction in children and adults with COPD or asthma. In case reports and small case series this technique proved useful for detecting CAO.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Central Airway Obstruction Using Impulse Oscillometry Before and After Interventional Bronchoscopy

Handa¹,

Huang

Murgu

et al. 2013

Respir Care

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BACKGROUND: Spirometry is used to physiologically assess patients with central airway obstruction (CAO) before and after interventional bronchoscopy, but is not always feasible in these patients, does not localize the anatomic site of obstruction, and may not correlate with the patient's functional impairment. Impulse oscillometry may overcome these limitations. We assessed the correlations between impulse oscillometry measurements, symptoms, and type of airway narrowing, before and after interventional bronchoscopy, and whether impulse oscillometry parameters can discriminate between fixed and dynamic CAO. METHODS: Twenty consecutive patients with CAO underwent spirometry, impulse oscillometry, computed tomography, dyspnea assessment, and bronchoscopy, before and after interventional bronchoscopy. The collapsibility index (the percent difference in airway lumen diameter during expiration versus during inspiration) was calculated using morphometric bronchoscopic images during quiet breathing. Variable CAO was defined as a collapsibility index of > 50%. Fixed CAO was defined as a collapsibility index of < 50%. The degree of obstruction was analyzed with computed tomography measurements. RESULTS: After interventional bronchoscopy, all impulse oscillometry measurements significantly improved, especially resistance at 5 Hz, which decreased from 0.67 ؎ 0.29kPa/L/s to 0.38 ؎ 0.17kPa/L/s (P < .001), and reactance at 20 Hz, which increased from -0.09 ؎ 0.11 to 0.03 ؎ 0.08 (P < .001). Changes in dyspnea score correlated with resistance at 5 Hz, the difference between the resistance at 5 Hz and the resistance at 20 Hz, and the reactance at 5 Hz, but not with spirometry measurements. The type of obstruction also correlated with dyspnea score, and showed distinct impulse oscillometry measurements. CONCLUSIONS: Impulse oscillometry measurements correlate with symptom improvements after interventional bronchoscopy. Impulse oscillometry might be useful to discriminate variable from fixed central airway obstruction. (University Hospital Medical Information Network, http://www.umin.ac.jp/english, ID000005322).

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“…FOT measures the mechanical impedance of the respiratory system (Z RS ) by evaluating its response to pressure oscillations (15). Z RS is commonly expressed in terms of resistance of the expiratory system (R RS ) and reactance of the respiratory system (X RS ), which in turn represents the elastic and inertive properties of the system.…”

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confidence: 99%

Optimal mean airway pressure during high-frequency oscillatory ventilation determined by measurement of respiratory system reactance

et al. 2013

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Background:The aims of the present study were (i) to characterize the relationship between mean airway pressure (P AW ) and reactance measured at 5 Hz (reactance of the respiratory system (X RS ) , forced oscillation technique) and (ii) to compare optimal P AW (P opt ) defined by X RS , oxygenation, lung volume (V L ), and tidal volume (V T ) in preterm lambs receiving high-frequency oscillatory ventilation (HFOV). Methods: Nine 132-d gestation lambs were commenced on HFOV at P AW of 14 cmH 2 O (P start ). P AW was increased stepwise to a maximum pressure (P max ) and subsequently sequentially decreased to the closing pressure (P cl , oxygenation deteriorated) or a minimum of 6 cmH 2 O, using an oxygenation-based recruitment maneuver. X RS , regional V L (electrical impedance tomography), and V T were measured immediately after (t 0min ) and 2 min after (t 2min ) each P AW decrement. P opt defined by oxygenation, X RS , V L , and V T were determined. results: The P AW -X RS and P AW -V T relationships were dome shaped with a maximum at P cl +6 cmH 2 O, the same point as P opt defined by V L . Below P cl +6 cmH 2 O, X RS became unstable between t 0min and t 2min and was associated with derecruitment in the dependent lung. P opt , as defined by oxygenation, was lower than the P opt defined by X RS , V L , or V T . conclusion: X RS has the potential as a bedside tool for optimizing P AW during HFOV. h igh-frequency oscillatory ventilation (HFOV) is used to treat severe neonatal lung disease and has the potential to reduce ventilator-induced lung injury when applied optimally (1,2). HFOV optimally applied aims to recruit the lung and subsequently reduce mean airway pressure (P AW ) to an optimal pressure (P opt ) that achieves optimal lung recruitment at the lowest distending pressure (open lung strategy) (3,4). However, identification and maintenance of P opt remains challenging, particularly in the newly born, whose lungs are in a highly dynamic state because of fluid reabsorption and establishment of functional residual capacity (5). The lack of appropriate tools for the bedside assessment and continuous monitoring of lung function in infants makes targeting of P opt even more difficult.Oxygenation, evaluated by monitoring oxygen saturation (Sp O2 ), is most commonly used for targeting P opt during HFOV in clinical practice (6). However, Sp O2 is an imperfect guide for P AW titration as it is relatively uniform over a wide range of airway pressures and volumes (7). Beginning with the observations of Suter et al. (8), the notion that lung mechanics can guide pressure settings during mechanical ventilation has been examined carefully. For conventional ventilation, a relationship between end-expiratory lung volume (V L ), recruitment, and tidal breath mechanics has been demonstrated repeatedly (9,10). During HFOV, the same theoretical considerations apply (3), but the best means of assessing the mechanics of the oscillated lung remains unclear.A promising approach to noninvasive bedside assessment of lung mechanics ...

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Oscillation Mechanics of Lungs and Chest in Man

Cited by 739 publications

References 0 publications

A comprehensive computational model of sound transmission through the porcine lung

A comprehensive computational model of sound transmission through the porcine lung

Assessment of Central Airway Obstruction Using Impulse Oscillometry Before and After Interventional Bronchoscopy

Optimal mean airway pressure during high-frequency oscillatory ventilation determined by measurement of respiratory system reactance

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