Mechanical properties of lungs and chest wall during spontaneous breathing

1980 ◽  
Vol 49 (3) ◽  
pp. 408-416 ◽  
Author(s):  
J. Nagels ◽  
F. J. Landser ◽  
L. van der Linden ◽  
J. Clement ◽  
K. P. Van de Woestijne
Keyword(s):  
Chest Wall ◽  
Healthy Subjects ◽  
Compartment Model ◽  
Simultaneous Increase ◽  
Chronic Obstructive ◽  
Forced Oscillation Technique ◽  
Compartment System ◽  
Lung Volumes ◽  
Obstructive Pulmonary Disease ◽  
Residual Capacity

Using a forced oscillation technique, we measured the resistance (Rrs) and reactance (Xrs) of the respiratory system between 2 and 32 Hz at three different lung volumes in 15 healthy subjects and 7 patients with chronic obstructive pulmonary disease. Rrs and Xrs were partitioned, by means of a pressure recording in the esophagus, into the resistance and reactance of lung and airways (L) and the chest wall. The measurements were validated by checking the adequacy of the frequency response of the esophagus, by the lack of difference between thoracic and mouth flow, by an estimation of the error introduced by the shunt impedance of the cheeks, and by comparisons with the values of pulmonary compliance and resistance determined in the same subjects with classical techniques. In both healthy subjects and patients, the chest wall has a low resistance that increases somewhat at low lung volumes and behaves functionally as a two-compartment system, with low capacitance at frequencies exceeding 4 Hz. Rrs varies with lung volume and is markedly frequency dependent in patients; both phenomena are due primarily to corresponding variations of RL. In healthy subjects, at and above functional residual capacity (FRC) level, the lungs behave as a one-compartment system, the reactance of which is mainly determined by the gaseous inertance, at least beyond 2 Hz. In patients and in healthy subjects breathing below FRC, the observed frequency dependence of resistance and the simultaneous increase in resonant frequency can be simulated satisfactorily by Mead's two-compartment model, assuming a large increase in peripheral airways resistance.

scholarly journals Respiratory system reactance reflects communicating lung volume in chronic obstructive pulmonary disease

2019 ◽  
Vol 126 (5) ◽  
pp. 1223-1231 ◽  
Author(s):  
Stephen Milne ◽  
Kanika Jetmalani ◽  
David G. Chapman ◽  
Joseph M. Duncan ◽  
Claude S. Farah ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Respiratory System ◽  
Lung Volume ◽  
Forced Oscillation ◽  
Chronic Obstructive ◽  
Forced Oscillation Technique ◽  
Obstructive Pulmonary Disease ◽  
Volume Relationship ◽  
Residual Capacity

Respiratory system reactance (Xrs) measured by the forced oscillation technique (FOT) is theoretically and experimentally related to lung volume. In chronic obstructive pulmonary disease (COPD), the absolute volume measured by body plethysmography includes a proportion that is inaccessible to pressure oscillations applied via the mouth, that is, a “noncommunicating” lung volume. We hypothesized that in COPD the presence of noncommunicating lung would disrupt the expected Xrs-volume relationship compared with plethysmographic functional residual capacity (FRCpleth). Instead, Xrs would relate to estimates of communicating volume, namely, expiratory reserve volume (ERV) and single-breath alveolar volume (VaSB). We examined FOT and lung function data from people with COPD ( n = 51) and from healthy volunteers ( n = 40). In healthy volunteers, we observed an expected inverse relationship between reactance at 5 Hz (X5) and FRCpleth. In contrast, there was no such relationship between X5 and FRCpleth in COPD subjects. However, there was an inverse relationship between X5 and both ERV and VaSB. Hence the theoretical Xrs-volume relationship is present in COPD but only when considering the communicating volume rather than the absolute lung volume. These findings confirm the role of reduced communicating lung volume as an important determinant of Xrs and therefore advance our understanding and interpretation of FOT measurements in COPD. NEW & NOTEWORTHY To investigate the determinants of respiratory system reactance (Xrs) measured by the forced oscillation technique (FOT) in chronic obstructive pulmonary disease (COPD), we examine the relationship between Xrs and lung volume. We show that Xrs does not relate to absolute lung volume (functional residual capacity) in COPD but instead relates only to the volume of lung in communication with the airway opening. This communicating volume may therefore be fundamental to our interpretation of FOT measurements in COPD and other pulmonary diseases.

scholarly journals Length and curvature of the dog diaphragm

2006 ◽  
Vol 101 (3) ◽  
pp. 794-798 ◽  
Author(s):  
Aladin M. Boriek ◽  
Ben Black ◽  
Rolf Hubmayr ◽  
Theodore A. Wilson
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Muscle Length ◽  
Lung Compliance ◽  
Chronic Obstructive ◽  
Phrenic Nerve Stimulation ◽  
Lung Volumes ◽  
Obstructive Pulmonary Disease ◽  
Transdiaphragmatic Pressure ◽  
Residual Capacity

Transdiaphragmatic pressure is a result of both tension in the muscles of the diaphragm and curvature of the muscles. As lung volume increases, the pressure-generating capability of the diaphragm decreases. Whether decrease in curvature contributes to the loss in transdiaphragmatic pressure and, if so, under what conditions it contributes are unknown. Here we report data on muscle length and curvature in the supine dog. Radiopaque markers were attached along muscle bundles in the midcostal region of the diaphragm in six beagle dogs of ∼8 kg, and marker locations were obtained from biplanar images at functional residual capacity (FRC), during spontaneous inspiratory efforts against a closed airway at lung volumes from FRC to total lung capacity, and during bilateral maximal phrenic nerve stimulation at the same lung volumes. Muscle length and curvature were obtained from these data. During spontaneous inspiratory efforts, muscle shortened by 15–40% of length at FRC, but curvature remained unchanged. During phrenic nerve stimulation, muscle shortened by 30 to nearly 50%, and, for shortening exceeding 52%, curvature appeared to decrease sharply. We conclude that diaphragm curvature is nearly constant during spontaneous breathing maneuvers in normal animals. However, we speculate that it is possible, if lung compliance were increased and the chest wall and the diameter of the diaphragm ring of insertion were enlarged, as in the case of chronic obstructive pulmonary disease, that decrease in diaphragm curvature could contribute to loss of diaphragm function.

scholarly journals The effect of increased lung volume in chronic obstructive pulmonary disease on upper airway obstruction during sleep

2015 ◽  
Vol 119 (3) ◽  
pp. 266-271 ◽  
Author(s):  
Paolo Biselli ◽  
Peter R. Grossman ◽  
Jason P. Kirkness ◽  
Susheel P. Patil ◽  
Philip L. Smith ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Lung Volume ◽  
Marked Reduction ◽  
Upper Airway ◽  
Airflow Limitation ◽  
Chronic Obstructive ◽  
Lung Volumes ◽  
Obstructive Pulmonary Disease ◽  
Copd Patients ◽  
Residual Capacity

Patients with chronic obstructive pulmonary disease (COPD) exhibit increases in lung volume due to expiratory airflow limitation. Increases in lung volumes may affect upper airway patency and compensatory responses to inspiratory flow limitation (IFL) during sleep. We hypothesized that COPD patients have less collapsible airways inversely proportional to their lung volumes, and that the presence of expiratory airflow limitation limits duty cycle responses to defend ventilation in the presence of IFL. We enrolled 18 COPD patients and 18 controls, matched by age, body mass index, sex, and obstructive sleep apnea disease severity. Sleep studies, including quantitative assessment of airflow at various nasal pressure levels, were conducted to determine upper airway mechanical properties [passive critical closing pressure (Pcrit)] and for quantifying respiratory timing responses to experimentally induced IFL. COPD patients had lower passive Pcrit than their matched controls (COPD: −2.8 ± 0.9 cmH2O; controls: −0.5 ± 0.5 cmH2O, P = 0.03), and there was an inverse relationship of subject's functional residual capacity and passive Pcrit (−1.7 cmH2O/l increase in functional residual capacity, r2 = 0.27, P = 0.002). In response to IFL, inspiratory duty cycle increased more ( P = 0.03) in COPD patients (0.40 to 0.54) than in controls (0.41 to 0.51) and led to a marked reduction in expiratory time from 2.5 to 1.5 s ( P < 0.01). COPD patients have a less collapsible airway and a greater, not reduced, compensatory timing response during upper airway obstruction. While these timing responses may reduce hypoventilation, it may also increase the risk for developing dynamic hyperinflation due to a marked reduction in expiratory time.

scholarly journals Action of the diaphragm on the rib cage

2016 ◽  
Vol 121 (2) ◽  
pp. 391-400 ◽  
Author(s):  
André De Troyer ◽  
Theodore A. Wilson
Keyword(s):  
Compartment Model ◽  
Pleural Pressure ◽  
Chronic Obstructive ◽  
Abdominal Pressure ◽  
Obstructive Pulmonary Disease ◽  
Rib Cage ◽  
Chest Wall Mechanics ◽  
Two Compartment Model ◽  
Residual Capacity ◽  
Lateral Walls

When the diaphragm contracts, pleural pressure falls, exerting a caudal and inward force on the entire rib cage. However, the diaphragm also exerts forces in the cranial and outward direction on the lower ribs. One of these forces, the “insertional force,” is applied by the muscle at its attachments to the lower ribs. The second, the “appositional force,” is due to the transmission of abdominal pressure to the lower rib cage in the zone of apposition. In the control condition at functional residual capacity, the effects of these two forces on the lower ribs are nearly equal and outweigh the effect of pleural pressure, whereas for the upper ribs, the effect of pleural pressure is greater. The balance between these effects, however, may be altered. When the abdomen is given a mechanical support, the insertional and appositional forces are increased, so that the muscle produces a larger expansion of the lower rib cage and, with it, a smaller retraction of the upper rib cage. In contrast, at higher lung volumes the zone of apposition is decreased, and pleural pressure is the dominant force on the lower ribs as well. Consequently, although the force exerted by the diaphragm on these ribs remains inspiratory, rib displacement is reversed into a caudal-inward displacement. This mechanism likely explains the inspiratory retraction of the lateral walls of the lower rib cage observed in many subjects with chronic obstructive pulmonary disease (Hoover's sign). These observations support the use of a three-compartment, rather than a two-compartment, model to describe chest wall mechanics.

scholarly journals Diagnostic performance of lung volumes in assessment of reversibility in chronic obstructive pulmonary disease

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Gamal Agmy ◽  
Manal A. Mahmoud ◽  
Azza Bahaa El-Din Ali ◽  
Mohamed Adam
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Cutoff Point ◽  
Whole Body ◽  
Significant Response ◽  
Chronic Obstructive ◽  
Lung Volumes ◽  
Obstructive Pulmonary Disease ◽  
Gold Stage ◽  
Clinically Significant

Abstract Background Reversibility measured by spirometry in chronic obstructive pulmonary disease (COPD) is defined as an increase in forced expiratory volume in first second (FEV1) that is both more than 12% and 200 mL above the pre-bronchodilator value in response to inhaled bronchodilators. FEV1 only may not fully reverberate the changes caused by reduction in air trapping or hyperinflation. To date, the studies that examined the effect of inhaled bronchodilators (BD) on residual volume (RV) and total lung capacity (TLC) are limited. This study was carried out to assess the differences between flow and volume responses after bronchodilator reversibility testing in patients with different COPD GOLD stages (GOLD stage I to stage IV). Spirometry and whole body plethysmography were done before and 15 min after inhalation of 400 μg salbutamol. Results Majority (53.3%) of cases were volume responders, 18.7% were flow responders, 20% were flow and volume responders, and 8% were non responders. Significant increase in Δ FEV1% was found in 15% of cases while 55% showed a significant increase in Δ FVC (P= < 0.001). Mean difference of Δ FVC (L) post BD was significantly increased with advancing GOLD stage (P= 0.03). A cutoff point > 20% for Δ RV% had 70% sensitivity and 60% specificity and > 12% for Δ TLC% showed 90% sensitivity and 45% specificity for prediction of clinically significant response to BD based on FEV1. A cutoff point > 18% for Δ RV% had 78% sensitivity and 29% specificity and > 14% for Δ TLC% had 50% sensitivity and 70% specificity for prediction of clinically significant response to BD based on FVC. Conclusion ΔFEV1 underestimates the true effect of bronchodilators with advancing GOLD stage. Measurement of lung volumes in addition to the standard spirometric indices is recommended when determining bronchodilator response in COPD patients.

scholarly journals Awakening efficacy of a vibrotactile device in patients on home nocturnal ventilatory assistance and healthy subjects as family caregiver proxies

2020 ◽  
Vol 17 ◽  
pp. 147997312098333
Author(s):  
Valerie Attali ◽  
Sophie Lavault ◽  
Antoine Guerder ◽  
Saba Al-Youssef ◽  
Benjamin Dudoignon ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Vibrotactile Stimulus ◽  
Chronic Obstructive ◽  
Vibrotactile Stimulation ◽  
Obstructive Pulmonary Disease ◽  
Copd Patients ◽  
Random Intervals ◽  
Healthy Family ◽  
Central Hypoventilation ◽  
Hypoventilation Syndrome

The objective of this study was to test the capacity of vibrotactile stimulation transmitted to the wrist bones by a vibrating wristband to awaken healthy individuals and patients requiring home mechanical ventilation during sleep. Healthy subjects (n = 20) and patients with central hypoventilation (CH) (Congenital Central Hypoventilation syndrome n = 7; non-genetic form of CH n = 1) or chronic obstructive pulmonary disease (COPD) (n = 9), underwent a full-night polysomnography while wearing the wristband. Vibrotactile alarms were triggered five times during the night at random intervals. Electroencephalographic (EEG), clinical (trunk lift) and cognitive (record the time on a sheet of paper) arousals were recorded. Cognitive arousals were observed for 94% of the alarms in the healthy group and for 66% and 63% of subjects in the CH and COPD groups, respectively (p < 0.01). The percentage of participants experiencing cognitive arousals for all alarms, was 72% for healthy subjects, 37.5% for CH patients and 33% for COPD patients (ns) (94%, 50% and 44% for clinical arousals (p < 0.01) and 100%, 63% and 44% for EEG arousals (p < 0.01)). Device acceptance was good in the majority of cases, with the exception of one CH patient and eight healthy participants. In summary this study shows that a vibrotactile stimulus is effective to induce awakenings in healthy subjects, but is less effective in patients, supporting the notion that a vibrotactile stimulus could be an effective backup to a home mechanical ventilator audio alarm for healthy family caregivers.

Effect of chest wall vibration on dyspnea during exercise in chronic obstructive pulmonary disease

2002 ◽  
Vol 130 (3) ◽  
pp. 305-316 ◽  
Author(s):  
Toshihide Fujie ◽  
Naoko Tojo ◽  
Naohiko Inase ◽  
Nobuo Nara ◽  
Ikuo Homma ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Chest Wall ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease
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