scholarly journals Effects of High Frequency Chest Compression on Respiratory System Mechanics in Normal Subjects and Cystic Fibrosis Patients

1995 ◽  
Vol 2 (1) ◽  
pp. 40-46 ◽  
Author(s):  
Richard L Jones ◽  
Richard T Lester ◽  
Neil E Brown
Keyword(s):  
Cystic Fibrosis ◽  
Airway Obstruction ◽  
Chest Compression ◽  
Respiratory System ◽  
High Frequency ◽  
Oscillation Frequency ◽  
Normal Subjects ◽  
Lung Mechanics ◽  
Normal Lung ◽  
Respiratory System Mechanics

OBJECTIVE: To investigate the short term effects of high frequency chest compression (HFCC) on several indices of respiratory system mechanics in normal subjects and patients with cystic fibrosis (CF).DESIGN: Comparative physiological approach. Subjects were blinded to 10 randomized HFCC settings (5, 10, 15, 20 and 25 Hz) with each applied at the lowest and at the highest background vest pressure.SETTING: Pulmonary function and lung mechanics laboratory, University of Alberta.PARTICIPANTS: Ten normal male volunteers (24.2±3.8 years) and 11 clinically stable CF patients (23.4±6.7 years). Normal subjects were nonsmokers who had normal lung function. The CF patients had a wide range of airway obstruction.INTERVENTIONS: HFCC was supplied by oscillating a pneumatic vest that covered the entire torso. Balloon tipped catheters were used to measure esophageal (Pes) and external chest wall (Pew) pressures. Changes in end-expiratory lung volume (EELV) during HFCC were measured from a spirogram and were compared with baseline functional residual capacity (FRC). The HFCC induced air movement al the mouth, oscillated tidal volume (Vosc), was measured by reverse plethysmography.RESULTS: Both normals and CF patients had similar changes in Pes and EELV. At the highest background vest pressure and at the higher oscillation frequencies, EELV decreased approximately 30% from the no-HFCC baseline FRC. Vosc decreased with increasing oscillation frequency but normals had higher Vosc than CF patients at each frequency. Conversion of Vose to flow (V˙osc) revealed that the highest Vosc occurred between 10 and 15 Hz for both normals and CF patients. Also, Vosc was dependent on the overall airway function. Low forced expired volume in 1 s resulted in low Vosc, especially when Vosc was measured during spontaneous expiration.CONCLUSIONS: CF patients with moderate or severe airway obstruction may gain maximal benefit from HFCC therapy when low vest pressure is used at an oscillation frequency of 10 to 15 Hz. The low vest pressure minimizes the decrease in EELV and 10 to 15 Hz maximizes Vosc.

Forced expiration: a test for airflow obstruction in horses

2000 ◽  
Vol 88 (5) ◽  
pp. 1870-1879 ◽  
Author(s):  
Laurent L. Couëtil ◽  
Frank S. Rosenthal ◽  
Chris M. Simpson
Keyword(s):  
Airway Obstruction ◽  
Airflow Obstruction ◽  
Lung Mechanics ◽  
Normal Lung ◽  
Chronic Obstructive ◽  
Forced Expiration ◽  
Obstructive Pulmonary Disease ◽  
Forced Expiratory Flow ◽  
Expiratory Flow ◽  
Histamine Challenge

The purpose of this study was to assess whether our method of inducing forced expiration detects small airway obstruction in horses. Parameters derived from forced expiratory flow-volume (FEFV) curves were compared with lung mechanics data obtained during spontaneous breathing in nine healthy horses, in three after histamine challenge, and in two with chronic obstructive pulmonary disease (COPD) pre- and posttherapy with prednisone. Parameters measured in the healthy horses included forced vital capacity (FVC = 41.6 ± 5.8 liters; means ± SD) and forced expiratory flow (FEF) at various percentages of FVC (range of 20.4–29.7 l/s). Histamine challenge induced a dose-dependent decrease in FVC and FEF at low lung volume. After therapy, lung function of the two COPD horses improved to a point where one horse had normal lung mechanics during tidal breathing; however, FEF at 95% of FVC (4.9 l/s) was still decreased. We concluded that FEFV curve analysis allowed the detection of induced or naturally occurring airway obstruction.

scholarly journals Aging-related changes in respiratory system mechanics and morphometry in mice

2016 ◽  
Vol 311 (1) ◽  
pp. L167-L176 ◽  
Author(s):  
Jonathan E. Elliott ◽  
Carlos B. Mantilla ◽  
Christina M. Pabelick ◽  
Anja C. Roden ◽  
Gary C. Sieck
Keyword(s):  
Respiratory System ◽  
Dynamic Compliance ◽  
Lung Mechanics ◽  
Collagen Deposition ◽  
Impedance Spectra ◽  
Respiratory System Mechanics ◽  
Linear Evolution ◽  
Respiratory System Resistance ◽  
Old Mice ◽  
Related Increase

Previous work investigating respiratory system mechanics in mice has reported an aging-related increase in compliance and mean linear intercept ( Lm). However, these changes were assessed using only a young (2-mo-old) and old (20- and 26-mo-old) group yet were interpreted to reflect a linear evolution across the life span. Therefore, to investigate respiratory system mechanics and lung morphometry across a more complete spectrum of ages, we utilized 2 (100% survival, n = 6)-, 6 (100% survival, n = 12)-, 18 (90% survival, n = 12)-, 24 (75% survival, n = 12)-, and 30 (25% survival, n = 12)-mo-old C57BL/6 mice. We found a nonlinear aging-related decrease in respiratory system resistance and increase in dynamic compliance and hysteresis between 2- and 24-mo-old mice. However, in 30-mo-old mice, respiratory system resistance increased, and dynamic compliance and hysteresis decreased relative to 24-mo-old mice. Respiratory system impedance spectra were measured between 1–20.5 Hz at positive end-expiratory pressures (PEEP) of 1, 3, 5, and 7 cmH2O. Respiratory system resistance and reactance at each level of PEEP were increased and decreased, respectively, only in 2-mo-old animals. No differences in the respiratory system impedance spectra were observed in 6-, 18-, 24-, and 30-mo-old mice. Additionally, lungs were fixed following tracheal instillation of 4% paraformaldehyde at 25 cmH2O and processed for Lm and airway collagen deposition. There was an aging-related increase in Lm consistent with emphysematous-like changes and no evidence of increased airway collagen deposition. Accordingly, we demonstrate nonlinear aging-related changes in lung mechanics and morphometry in C57BL/6 mice.

scholarly journals In Vitro Estimation of Relative Compliance during High-Frequency Oscillatory Ventilation

2021 ◽  
Vol 11 (3) ◽  
pp. 899
Author(s):  
Jan Matejka ◽  
Martin Rozanek ◽  
Jakub Rafl ◽  
Petr Kudrna ◽  
Karel Roubik
Keyword(s):  
Physical Model ◽  
Respiratory System ◽  
High Frequency ◽  
High Frequency Oscillatory Ventilation ◽  
Opening Pressure ◽  
Respiratory System Mechanics ◽  
Oscillatory Ventilation ◽  
Airway Opening ◽  
High Frequency Oscillatory

High-frequency oscillatory ventilation (HFOV), which uses a small tidal volume and a high respiratory rate, is considered a type of protective lung ventilation that can be beneficial for certain patients. A disadvantage of HFOV is its limited monitoring of lung mechanics, which complicates its settings and optimal adjustment. Recent studies have shown that respiratory system reactance (Xrs) could be a promising parameter in the evaluation of respiratory system mechanics in HFOV. The aim of this study was to verify in vitro that a change in respiratory system mechanics during HFOV can be monitored by evaluating Xrs. We built an experimental system consisting of a 3100B high-frequency oscillatory ventilator, a physical model of the respiratory system with constant compliance, and a system for pressure and flow measurements. During the experiment, models of different constant compliance were connected to HFOV, and Xrs was derived from the impedance of the physical model that was calculated from the spectral density of airway opening pressure and spectral cross-power density of gas flow and airway opening pressure. The calculated Xrs changed with the change of compliance of the physical model of the respiratory system. This method enabled monitoring of the trend in the respiratory system compliance during HFOV, and has the potential to optimize the mean pressure setting in HFOV in clinical practice.

Partitioning of respiratory mechanics in mechanically ventilated patients

1991 ◽  
Vol 71 (6) ◽  
pp. 2425-2433 ◽  
Author(s):  
G. Polese ◽  
A. Rossi ◽  
L. Appendini ◽  
G. Brandi ◽  
J. H. Bates ◽  
...  
Keyword(s):  
Pulmonary Edema ◽  
Chest Wall ◽  
Respiratory System ◽  
Lung Mechanics ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Mechanically Ventilated ◽  
Mechanically Ventilated Patients ◽  
Respiratory System Mechanics ◽  
Ventilated Patients

In ten mechanically ventilated patients, six with chronic obstructive pulmonary disease (COPD) and four with pulmonary edema, we have partitioned the total respiratory system mechanics into the lung (l) and chest wall (w) mechanics using the esophageal balloon technique together with the airway occlusion technique during constant-flow inflation (J. Appl. Physiol. 58: 1840–1848, 1985). Intrinsic positive end-expiratory pressure (PEEPi) was present in eight patients (range 1.1–9.8 cmH2O) and was due mainly to PEEPi,L (80%), with a minor contribution from PEEPi,w (20%), on the average. The increase in respiratory elastance and resistance was determined mainly by abnormalities in lung elastance and resistance. Chest wall elastance was slightly abnormal (7.3 +/- 2.2 cmH2O/l), and chest wall resistance contributed only 10%, on the average, to the total. The work performed by the ventilator to inflate the lung (WL) averaged 2.04 +/- 0.59 and 1.25 +/- 0.21 J/l in COPD and pulmonary edema patients, respectively, whereas Ww was approximately 0.4 J/l in both groups, i.e., close to normal values. We conclude that, in mechanically ventilated patients, abnormalities in total respiratory system mechanics essentially reflect alterations in lung mechanics. However, abnormalities in chest wall mechanics can be relevant in some COPD patients with a high degree of pulmonary hyperinflation.

Compliance of the chest wall in chronic bronchitis and emphysema

1963 ◽  
Vol 18 (4) ◽  
pp. 707-711 ◽  
Author(s):  
R. M. Cherniack ◽  
A. Hodson
Keyword(s):  
Airway Obstruction ◽  
Chronic Bronchitis ◽  
Chest Wall ◽  
Respiratory System ◽  
Vital Capacity ◽  
Normal Subjects ◽  
Chest Wall Compliance ◽  
Paradoxical Finding ◽  
Wall Compliance ◽  
Work Done

The respiratory rate was found to be faster and the tidal volume lower than normal in patients with chronic bronchitis and emphysema. The compliance of the total respiratory system, the lungs, and the chest wall was measured in 11 normal subjects and 13 patients with chronic bronchitis, 11 of whom had also developed emphysema. The compliance of the total respiratory system was lower than in the normals in the patients with chronic bronchitis. This was entirely attributable to a reduction in the compliance of the chest wall, that of the lungs being similar to that of the normals. The vital capacity appeared to be related to the compliance of the total respiratory system and was reduced in the patients with chronic bronchitis and emphysema largely because of a diminished distensibility of the chest wall. It is suggested that the low chest wall compliance may explain the paradoxical finding of rapid shallow respirations in these patients with airway obstruction who theoretically would have been expected to breathe slowly and deeply. It is further suggested that the diminished distensibility of the chest wall in patients with chronic bronchitis and emphysema would necessitate an increase in the amount of work done in order to breathe and, therefore, likely contributes to the disability in this disease. Submitted on April 18, 1962

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