<p>Area under the forced expiratory flow-volume loop in spirometry indicates severe hyperinflation in COPD patients</p>

The flow-volume (FV) loop is another way of representing spirometric data from combinations of forced expiratory and forced inspiratory vital capacity breaths. The FV loop is of use in identifying, and often localizing, lesions of the larynx and the trachea (down to the carina). Three general patterns have been recognized. When the lesion behaves in a fixed fashion (as might occur with an artificial orifice), maximal expiratory and inspiratory flows are almost equally compromised. This results in a rectangular FV loop, irrespective of whether the lesion is located intrathoracically or extrathoracically. When the lesion behaves in a variable fashion, two distinct patterns are seen, depending on the location of the lesion (intrathoracic or extrathoracic). The variable lesion acts as a fixed lesion during one phase of forced respiration only. The extrathoracic variable lesion results in a predominant reduction in forced inspiratory flow, with little effect on expiratory flow, whereas the intrathoracic variable lesion produces a characteristic reduction in expiratory flow. These patterns reflect the transmural forces existing at the site of the lesion.

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Shape of Forced Expiratory Flow-Volume Curves in Infants

American Review of Respiratory Disease ◽

10.1164/ajrccm/138.3.590 ◽

1988 ◽

Vol 138 (3) ◽

pp. 590-597 ◽

Cited By ~ 27

Author(s):

Peter N. Le Souëf ◽

Daniel M. Hughes ◽

Louis I. Landau

Keyword(s):

Flow Volume ◽

Forced Expiratory Flow ◽

Expiratory Flow

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SMART BIOFEEDBACK EXPECTORANT SYSTEM FOR IMPROVING THE LUNG CAPACITIES

10.31224/osf.io/4bqkp ◽

2020 ◽

Cited By ~ 1

Author(s):

S. Anandh ◽

R. Vasuki ◽

Raid Saleem Al Baradie

Keyword(s):

Side Effects ◽

Flow Rate ◽

Pressure Sensor ◽

Feedback System ◽

Flow Volume ◽

Sampled Data ◽

Time Duration ◽

The Status ◽

Forced Expiratory Flow ◽

Expiratory Flow

The Biofeedback Expectorant is a device which is designed for patients sufferingfrom various lung disorders, associated with the production and secretion of excessivequantities of mucus within the airways and help to loosen the mucous so that it tendsto be hacked from the lungs. Meanwhile, the mucous in the lungs becomes thick anddifficult to wash out from the air routes. When this mucous remain in the air routes, itblocks airways and becomes hard to relax. The disease is likely to be conceivable ifthe mucous remains permanently in the air routes. When one breathes out through thisdevice, it bounces the ball inside to it. This action produces signals around 15 Hz andforward the vibration via the air ways. This amalgamation of enhanced intensity andvibration aids the mucous in moving into the air ways where it remains. Some patientscan’t blow for a longer duration, therefore a feedback system is designed in such away that the pressure is measured using a pressure sensor. If the value goes below thecertain threshold limit the beep sound is heard and a light indication is provided sothat we can find whether the patient should blow effectively. The Blowing time (howmuch time duration the patient is blowing) was measured and display in the LCDscreen. The forced expiratory flow volume (FEV1) and Peak Expiratory Flow Rate(PEFR) was calculated that gives an idea about the status of the lungs. The MannWhitney U Test was conducted with α = 0.05 for the sampled data, the results showthat the data is statistically significant. This device is small, portable, and easy to usewith no side effects.

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Expiratory airflow limitation and hyperinflation during methacholine-induced bronchoconstriction

Journal of Applied Physiology ◽

10.1152/jappl.1993.75.4.1720 ◽

1993 ◽

Vol 75 (4) ◽

pp. 1720-1727 ◽

Cited By ~ 37

Author(s):

R. Pellegrino ◽

B. Violante ◽

S. Nava ◽

C. Rampulla ◽

V. Brusasco ◽

...

Keyword(s):

Lung Volume ◽

Healthy Subjects ◽

Dynamic Compression ◽

Airflow Limitation ◽

Forced Flow ◽

Moderate Increase ◽

Flow Volume ◽

Airway Caliber ◽

Forced Expiratory Flow ◽

Expiratory Flow

To investigate the role of airflow limitation on the increase of end-expiratory lung volume (EELV) during bronchoconstriction, nine stable asthmatic subjects and seven healthy subjects were challenged with inhaled methacholine (MCh). Changes in airway caliber were assessed by using forced expiratory volume in 1 s, partial forced expiratory flow at 50% of control forced vital capacity, and specific airway conductance. To detect airflow limitation, tidal flow-volume curves were superimposed on partial forced flow-volume curves at absolute lung volume. The electromyogram of the diaphragm was recorded by surface electrodes in four asthmatic and four healthy subjects, and the electrical diaphragmatic activity (DIA) during expiration was expressed as a percentage of the duration of expiratory time. In 10 subjects (9 asthmatic and 1 healthy) the partial forced expiratory flow recorded after some MCh dose impinged on tidal expiratory flow recorded before MCh. When this occurred it was associated with an increase in EELV by 0.54 +/- 0.07 (SE) liter (P < 0.001), which was larger than that occurring when lower MCh doses (0.11 +/- 0.04 liter, P < 0.05) were used, and with a moderate increase in DIA of 15 +/- 2.5% (P < 0.01). Six healthy subjects did not increase EELV after MCh despite a significant degree of bronchoconstriction; in these subjects tidal expiratory flow never impinged on forced expiratory flow, and DIA never increased. These results suggest that hyperinflation during MCh-induced bronchoconstriction is triggered by dynamic compression of the airways and is associated with moderate increase of DIA during expiration.

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