Airway pressure-volume curve estimated by flow interruption during forced expiration

1989 ◽  
Vol 67 (6) ◽  
pp. 2631-2638 ◽  
Author(s):  
N. Ohya ◽  
J. Huang ◽  
T. Fukunaga ◽  
H. Toga
Keyword(s):  
Maximum Flow ◽  
Normal Subjects ◽  
Chronic Obstructive ◽  
Forced Expiration ◽  
Obstructive Pulmonary Disease ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
Mouth Pressure ◽  
Short Period ◽  
Volume Characteristics

We attempted to estimate the pressure-volume characteristics of airways downstream from the choke point when the airflow was abruptly interrupted during forced expiration. The change of gas volume of the downstream segment after interruption could be estimated by multiplying the maximum flow (Vmax) immediately before interruption by the interruption time because the Vmax is maintained for a short period after airflow interruption at the mouth, as described in our previous report (J. Appl. Physiol. 66: 509-517, 1989). For the pressure of the downstream segment, we used the mouth pressure itself. Airway compliance, a slope of the pressure-volume curve, was measured in an airway model in eight normal subjects, in six patients with chronic obstructive pulmonary disease (COPD), and in one patient with tracheobronchopathia osteochondroplastica. Airway compliance was 0.96 ml/cmH2O in normal subjects and 2.49 ml/cmH2O in COPD patients. This difference of airway compliance was believed to be caused by the longitudinal expansion of the downstream segment and changes in the properties of the airway wall.

Detection of expiratory flow limitation during exercise in COPD patients

1997 ◽  
Vol 82 (3) ◽  
pp. 723-731 ◽  
Author(s):  
Nickolaos G. Koulouris ◽  
Ioanna Dimopoulou ◽  
Päivi Valta ◽  
Richard Finkelstein ◽  
Manuel G. Cosio ◽  
...  
Keyword(s):  
Normal Subjects ◽  
Chronic Obstructive ◽  
Flow Limitation ◽  
Expiratory Flow Limitation ◽  
Obstructive Pulmonary Disease ◽  
Normal Limits ◽  
Volume Curve ◽  
Copd Patients ◽  
Flow Volume Curve ◽  
Expiratory Flow

Koulouris, Nickolaos G., Ioanna Dimopoulou, Päivi Valta, Richard Finkelstein, Manuel G. Cosio, and J. Milic-Emili.Detection of expiratory flow limitation during exercise in COPD patients. J. Appl. Physiol. 82(3): 723–731, 1997.—The negative expiratory pressure (NEP) method was used to detect expiratory flow limitation at rest and at different exercise levels in 4 normal subjects and 14 patients with chronic obstructive pulmonary disease (COPD). This method does not require performance of forced expirations, nor does it require use of body plethysmography. It consists in applying negative pressure (−5 cmH2O) at the mouth during early expiration and comparing the flow-volume curve of the ensuing expiration with that of the preceding control breath. Subjects in whom application of NEP does not elicit an increase in flow during part or all of the tidal expiration are considered flow limited. The four normal subjects were not flow limited up to 90% of maximal exercise power output (W˙max). Five COPD patients were flow limited at rest, 9 were flow limited at one-third W˙max, and 12 were flow limited at two-thirdsW˙max. Whereas in all patients who were flow limited at rest the maximal O2 uptake was below the normal limits, this was not the case in most of the other patients. In conclusion, NEP provides a rapid and reliable method to detect expiratory flow limitation at rest and during exercise.

An analysis of pressure-volume characteristics of the lungs

1964 ◽  
Vol 19 (1) ◽  
pp. 97-104 ◽  
Author(s):  
Eduardo Salazar ◽  
John H. Knowles
Keyword(s):  
Transpulmonary Pressure ◽  
Normal Subjects ◽  
Mean Value ◽  
Inflation Pressure ◽  
Inspiratory Capacity ◽  
Volume Curve ◽  
Pressure Volume Curve ◽  
The Mean ◽  
Volume Characteristics ◽  
Pulmonary Volume

By analysis of the retractive forces of the lungs it was found that the pressure-volume characteristics of the lungs may be expressed by an exponential function. The curve described by such expression could be fitted to the experimental data obtained in 20 normal subjects. A half-inflation pressure (h) was defined which makes possible the evaluation of the retractive forces of the lungs by a measurement independent of lung size and accounting for known curvilinearity. H is a useful index of the stiffness of the organ and it is defined as the increase in transpulmonary pressure necessary to inflate the lungs halfway to the maximal pulmonary volume from any resting level. The mean value of h for the group was 7.58 ± 2.53 cm H2O. The half-inflation pressure is independent of the level of measurement within the inspiratory capacity and it does not vary with or depend on the size of the lungs. It may therefore be a more useful expression of the retractive forces of the lungs than compliance. pulmonary retractive forces; lung stiffness; compliance half-inflation pressure and lung size; VC and half-inflation pressure; FRC and half-inflation pressure; new expression for compliance; pressure-volume curve Submitted on March 4, 1963

A new method for measurement of respiratory resistance

1983 ◽  
Vol 54 (2) ◽  
pp. 594-597 ◽  
Author(s):  
C. F. Shaw ◽  
S. T. Chiang ◽  
Y. C. Hsieh ◽  
J. Milic-Emili ◽  
C. Lenfant
Keyword(s):  
Respiratory System ◽  
Normal Subjects ◽  
The Body ◽  
New Method ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Respiratory Flow ◽  
Short Period ◽  
Airway Opening ◽  
Partially Occluded

A new method for measuring the resistance of the total respiratory system is presented. The method uses a device comprising a solenoid valve, a multiperforated plate, and a pneumotachograph. The multiperforated plate serves as a constant resistor (Rk) that is used to partially occlude the airway opening, thus rapidly and briefly reducing airflow during natural expiration. If it is assumed that the driving pressure remains constant during the very short period the airway is partially occluded, the respiratory flow immediately preceding the addition of Rk (V) and the flow reduction during partial occlusion (delta V) allow calculation of the resistance of the total respiratory system. The resistance of 14 normal subjects and 18 patients with chronic obstructive pulmonary disease (COPD) was measured with this new method as well as with the body plethysmographic method: 90% of the interrupter values fell within +/- 0.6 cmH2O . l-1.s of the plethysmographic values, and all fell within +/- 0.8 cmH2O . l-1.s.

scholarly journals Prehospital emergency medical technicians can perform ultrasonography and blood analysis in prehospital evaluation of patients with chronic obstructive pulmonary disease: a feasibility study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Giti Nadim ◽  
Christian B. Laursen ◽  
Pia I. Pietersen ◽  
Daniel Wittrock ◽  
Michael K. Sørensen ◽  
...  
Keyword(s):  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Respiratory Insufficiency ◽  
Emergency Departments ◽  
Emergency Medical Technicians ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Emergency Medical ◽  
Short Period ◽  
Release Strategy

Abstract Introduction Crowding of the emergency departments is an increasing problem. Many patients with an exacerbation of chronic obstructive pulmonary disease (COPD) are often treated in the emergency departments for a very short period before discharged to their homes. It is possible that this treatment could take place in the patients’ homes with sufficient diagnostics supporting the treatment. In an effort to keep the diagnostics and treatment of some of these patients in their homes and thus to reduce the patient load at the emergency departments, we implemented a prehospital treat-and-release strategy based on ultrasonography and blood testing performed by emergency medical technicians (EMT) or paramedics (PM) in patients with acute exacerbation of COPD. Method EMTs and PMs were enrolled in a six-hour educational program covering ultrasonography of the lungs and point of care blood tests. During the seasonal peak of COPD exacerbations (October 2018 – May 2019) all patients who were treated by the ambulance crews for respiratory insufficiency were screened in the ambulances. If the patient had uncomplicated COPD not requiring immediate transport to the hospital, ultrasonographic examination of the lungs, measurements of C-reactive protein and venous blood gases analyses were performed. The response to the initial treatment and the results obtained were discussed via telemedical consultation with a prehospital anaesthesiologist who then decided to either release the patient at the scene or to have the patient transported to the hospital. The primary outcome was strategy feasibility. Results We included 100 EMTs and PMs in the study. During the study period, 771 patients with respiratory insufficiency were screened. Uncomplicated COPD was rare as only 41patients were treated according to the treat-and-release strategy. Twenty of these patients (49%) were released at the scene. In further ten patients, technical problems were encountered hindering release at the scene. Conclusion In a few selected patients with suspected acute exacerbations of COPD, it was technically and organisationally feasible for EMTs and PMs to perform prehospital POCT-ultrasound and laboratory testing and release the patients following treatment. None of the patients released at the scene requested a secondary ambulance within the first 48 h following the intervention.

In vivo characterization of the transitional bronchioles by aerosol-derived airway morphometry

1999 ◽  
Vol 87 (3) ◽  
pp. 920-927 ◽  
Author(s):  
Kirby L. Zeman ◽  
Gerhard Scheuch ◽  
Knut Sommerer ◽  
James S. Brown ◽  
William D. Bennett
Keyword(s):  
Ex Vivo ◽  
Normal Subjects ◽  
Characteristic Line ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
Lung Capacity ◽  
Single Breath ◽  
In Vivo Characterization

Effective airway dimensions (EADs) were determined in vivo by aerosol-derived airway morphometry as a function of volumetric lung depth (VLD) to identify and characterize, noninvasively, the caliber of the transitional bronchiole region of the human lung and to compare the EADs by age, gender, and disease. By logarithmically plotting EAD vs. VLD, two distinct regions of the lung emerged that were identified by characteristic line slopes. The intersection of proximal and distal segments was defined as VLDtransand associated EADtrans. In our normal subjects ( n = 20), VLDtrans [345 ± 83 (SD) ml] correlated significantly with anatomic dead space (224 ± 34 ml) and end of phase II of single-breath nitrogen washout (360 ± 53 ml). The corresponding EADtranswas 0.42 ± 0.07 mm, in agreement with other ex vivo measurements of the transitional bronchioles. VLDtrans was smaller (216 ± 64 ml) and EADtrans was larger (0.83 ± 0.04 mm) in our patients with chronic obstructive pulmonary disease ( n = 13). VLDtrans increased with age for children (age 8–18 yr; P = 0.006, n = 26) and with total lung capacity for age 8–81 yr ( P < 0.001, n = 61). This study extends the usefulness of aerosol-derived airway morphometry to in vivo measurements of the transitional bronchioles.

Abstract 16961: Time-dependent Markers of Chronic Obstructive Pulmonary Disease Severity and Change are Associated With Increased Risk of Mortality in the General Heart Failure Population: A National Study of 50,114 Patients From the United Kingdom

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Claire A Rushton ◽  
Lucy Riley ◽  
Duwarakan K Satchithananda ◽  
Peter W Jones ◽  
Umesh T Kadam
Keyword(s):  
Heart Failure ◽  
Chronic Obstructive Pulmonary Disease ◽  
Pulmonary Disease ◽  
Chronic Obstructive ◽  
Forced Expiration ◽  
Obstructive Pulmonary Disease ◽  
Gold Stage ◽  
Risk Of Mortality ◽  
Increased Risk

Purpose: Heart failure (HF) carries poor prognosis which changes over time. Chronic obstructive pulmonary disease (COPD) is common in HF and increases risk of mortality but how COPD severity and change influences HF prognosis is unknown. We hypothesised that in the HF general population, comorbidity stratification by increasing severity and longitudinal change would be associated with increased mortality. Methods: We used a case-control study nested within the UK Clinical Practice Research Datalink database (12-year time-period to 2014), of newly diagnosed HF patients aged over 40 years. Using risk set sampling, four controls were matched to cases on calendar and follow-up time. Routinely collected clinical measures of severity and change for COPD were (i) forced expiration volume in 1 second (FEV 1 ) stages, defined by Global Initiatives for Chronic Obstructive Lung Disease (GOLD) guidelines and (ii) prescribed medications in two time-windows covering 1-year prior to the match date. Conditional logistic regression was used to estimate risk ratios (RR) for all-cause mortality adjusted for known confounders. Results: Of the 50,114 HF sample, 5,848 (11.7%) had COPD and of these 62% died during follow-up compared to 52% of patients without COPD. COPD comorbidity risk associated with mortality stratified by GOLD stages was as follows: stage 1; adjusted RR 1.73 (95% CI 1.50-1.99) to stage 4; 3.14 (2.65, 3.73). Estimates for COPD FEV 1 change compared to no COPD were: GOLD stage same or better; 2.15 (1.97, 2.34) and GOLD stage worse; 2.70 (2.30, 3.17). The mortality estimates for medications severity were: inhalers only 1.13 (1.07,1.19), oral steroids; 1.83 (1.69,1.97) and oxygen; 2.94 (2.47, 3.51). The estimates for medications change were: no new steroids or oxygen; 1.22, (1.16, 1.28), new steroids but not oxygen; 1.84, (1.67,1.28) and new on oxygen; 3.41, (2.71,4.29). Conclusions: COPD is an important and common comorbidity in HF. Our results show that worse COPD severity and recent change based on routinely collected clinical data was associated with increased mortality and provides key prognostic information for clinical assessment in practice.

Frequency characteristics of airway and tissue impedances in respiratory diseases

1991 ◽  
Vol 71 (1) ◽  
pp. 259-270 ◽  
Author(s):  
M. Mishima ◽  
K. Kawakami ◽  
K. Higashiya ◽  
T. Fukunaga ◽  
T. Ooka ◽  
...  
Keyword(s):  
Chest Wall ◽  
Random Noise ◽  
Peripheral Resistance ◽  
Normal Subjects ◽  
Frequency Characteristics ◽  
Chronic Obstructive ◽  
Obstructive Pulmonary Disease ◽  
The Real ◽  
Peripheral Airway ◽  
Chronic Pulmonary Emphysema

We measured the frequency characteristics (at 10–40 Hz) of airway (Za) and tissue (Zt) impedances in cases of chronic obstructive pulmonary disease [asthmatic bronchitis (AB), chronic pulmonary emphysema (CPE)] and interstitial pneumonitis (IP) by use of an improved random noise oscillation and body box method. The results were then compared with those obtained for normal subjects. The real part of Za was markedly elevated in patients with AB but only slightly elevated in those with CPE. To interpret these data we used an electromechanical analogue including serial inhomogeneity with shunt impedance. From this model we concluded that AB causes both the central and peripheral airway resistances to increase, while CPE brings about a rise mainly in peripheral resistance. In IP patients, only the imaginary part of Zt decreased, which might reflect the decrease in both lung and chest wall compliance. In CPE patients, but not in AB patients, the real part of Zt fell. These data were consistent with the assumption that the decrease in mass per unit volume of lung tissue and hyperinflation of the chest wall in CPE patients might lower the tissue resistances.

Assessment of transdiaphragmatic pressure in humans

1985 ◽  
Vol 58 (5) ◽  
pp. 1469-1476 ◽  
Author(s):  
D. Laporta ◽  
A. Grassino
Keyword(s):  
Pulmonary Disease ◽  
Visual Feedback ◽  
Random Order ◽  
Normal Subjects ◽  
Chronic Obstructive ◽  
Disease Group ◽  
Obstructive Pulmonary Disease ◽  
Transdiaphragmatic Pressure ◽  
Residual Capacity ◽  
Group 1

Maximal force developed by the diaphragm at functional residual capacity is a useful index to establish muscle weakness; however, great disparity in its reproducibility can be observed among reports in the literature. We evaluated five maneuvers to measure maximal transdiaphragmatic pressure (Pdimax) in order to establish best reproducibility and value. Thirty-five naive subjects, including 10 normal subjects (group 1), 12 patients with chronic obstructive pulmonary disease (group 2), and 13 patients with restrictive pulmonary disease (group 3), were studied. Each subject performed five separate maneuvers in random order that were repeated until reproducible values were obtained. The maneuvers were Mueller with (A) and without mouthpiece (B), abdominal expulsive effort with open glottis (C), two-step (maneuver C combined with Mueller effort) (D), and feedback [two-step with visual feedback of pleural (Ppl) and abdominal (Pab) pressure] (E). The greatest reproducible Pdimax values were obtained with maneuver E (P less than 0.01) (group 1: 180 +/- 14 cmH2O). The second best maneuvers were A, B, and D (group 1: 154 +/- 25 cmH2O). Maneuver C produced the lowest values. For all maneuvers, group 1 produced higher values than groups 2 and 3 (P less than 0.001), which were similar. The Ppl to Pdi ratio was 0.6 in maneuvers A and B, 0.4 in D and E, and 0.2 in C. We conclude that visual feedback of Ppl and Pab helped the subjects to elicit maximal diaphragmatic effort in a reproducible fashion. It is likely that the great variability of values in Pdimax previously reported are the result of inadequate techniques.

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