 Flow-Volume loop showing successful FVC maneuver. Positive values represent expiration, negative values represent inspiration. The trace moves clockwise for expiration followed by inspiration. (Note the FEV1, FEV1/2 and FEV3 values are arbitrary in this graph and just shown for illustrative purposes, they must be recorded as part of the experiment). Spirometry (meaning the measuring of breath) is the most common of the Pulmonary Function Tests (PFTs), measuring lung function, specifically the measurement of the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled. Spirometry is an important tool used for generating pneumotachograph to assessing conditions such as asthma, pulmonary fibrosis, and COPD. Image File history File links Download high resolution version (927x733, 74 KB)Spriometry Flow-Volume loop. ...
Image File history File links Download high resolution version (927x733, 74 KB)Spriometry Flow-Volume loop. ...
Image File history File linksMetadata Download high resolution version (827x740, 323 KB)Printout of a Spirometer report. ...
Image File history File linksMetadata Download high resolution version (827x740, 323 KB)Printout of a Spirometer report. ...
Human respiratory system The lungs flank the heart and great vessels in the chest cavity. ...
Diffuse parenchymal lung disease (DPLD), also known as interstitial lung disease, refers to a group of lung diseases, affecting the alveolar epithelium, pulmonary capillary endothelium, basement membrane, perivascular and perilymphatic tissues. ...
Chronic obstructive pulmonary disease (COPD), also known as chronic obstructive airway disease (COAD), is a group of diseases characterized by limitation of airflow in the airway that is not fully reversible. ...
Spirometry testing The spirometry test is performed using a device called a spirometer, which comes in several different varieties. Most spirometers display the following graphs: A spirometer is an apparatus for measuring the volume of air inspired and expired by the lungs. ...
- a volume-time curve, showing volume (liters) along the Y-axis and time (seconds) along the X-axis
- a flow-volume loop, which graphically depicts the rate of airflow on the Y-axis and the total volume inspired or expired on the X-axis
The most commonly used guidelines for spirometric testing and interpretation are set by the American Thoracic Society (ATS) and the European Respiratory Society (ERS). American Thoracic Society (ATS ), established in 1905, is an independently incorporated, international, educational and scientific society, serving its 18,000 members world-wide who are dedicated in respiratory and critical care medicine. ...
Procedure The basic FVC test varies slightly depending on the equipment used.
Generally, the patient is asked to take the deepest breath they can, and then exhale into the sensor as hard as possible, for as long as possible. It is sometimes directly followed by a rapid inhalation (inspiration), in particular when assessing possible upper airway obstruction. Sometimes, the test will be preceded by a period of quiet breathing in and out from the sensor (tidal volume), or the rapid breath in (forced inspiratory part) will come before the forced exhalation. Airway obstruction is a respiratory problem caused by increased resistance in the bronchioles (usually from a decreased radius of the bronchioles) that reduces the amount of air inhaled in each breath and the oxygen that reaches the pulmonary arteries. ...
During the test, soft nose clips may be used to prevent air escaping through the nose. Filter mouthpieces may be used to prevent the spread of microorganisms, particularly for inspiratory maneuvers.
Limitations of test The maneuver is highly dependent on patient cooperation and effort, and is normally repeated at least three times to ensure reproducibility. Since results are dependent on patient cooperation, FEV1 and FVC can only be underestimated, never overestimated.
Due to the patient cooperation required, spirometry can only be used on children old enough to comprehend and follow the instructions given (typically about 4-5 years old), and only on patients who are able to understand and follow instructions - thus, this test is not suitable for patients who are unconscious, heavily sedated, or have limitations that would interfere with vigorous respiratory efforts. Other types of lung function tests are available for infants and unconscious persons.
Related tests Spirometry can also be part of a bronchial challenge test, used to determine bronchial hyperresponsiveness to either rigorous exercise, inhalation of cold/dry air, or with a pharmaceutical agent such as methacholine or histamine. There are some respiratory diseases such as exercise-induced asthma that are not apparent unless the patient is exposed to some sort of trigger, such as a chemical irritant, an allergen, cold or dry air, or rigorous exercise. ...
The bronchioles are the first airway branches that no longer contain cartilage. ...
Methacholine is a synthetic choline ester that acts as a non-selective muscarinic receptor agonist in the parasympathetic nervous system. ...
This article or section does not cite any references or sources. ...
Sometimes, to assess the reversibility of a particular condition, a bronchodilator is administered before performing another round of tests for comparison. This is commonly referred to as a reversibility test, or a post bronchodilator test (Post BD), and is an important part in diagnosing asthma versus COPD. A bronchodilator is a medication intended to improve bronchial airflow. ...
Explanation of common test values in FVC tests | Abbreviation | Name | Description | | FVC | Forced Vital Capacity | This is the total amount of air that you can forcibly blow out after full inspiration, measured in liters. | | FEV1 | Forced Expiratory Volume in 1 Second | This is the amount of air that you can forcibly blow out in one second, measured in litres. Along with FVC it is considered one of the primary indicators of lung function. | | FEV1 / FVC | FEV1% | This is the ratio of FEV 1 to FVC. In healthy adults this should be approximately 75 - 80%. | | PEF | Peak Expiratory Flow | This is the speed of the air moving out of your lungs at the beginning of the expiration, measured in liters per second. | | FEF 25-75% or 25-50% | Forced Expiratory Flow 25-75% or 25-50% | This is the average flow (or speed) of air coming out of the lung during the middle portion of the expiration (also sometimes referred to as the MMEF, for maximal mid-expiratory flow). | | FIF 25-75% or 25-50% | Forced Inspiratory Flow 25%-75% or 25%-50% | This is similar to FEF 25%-75% or 25%-50% except the measurement is taken during inspiration. | | FET | Forced Expiratory Time | This measures the length of the expiration in seconds. | | SVC | Slow Vital capacity | | | TV | Tidal Volume | During the respiratory cycle, a specific volume of air is drawn into and then expired out of the lungs. This volume is tidal volume. | | MVV | Maximum Voluntary Ventilation | a measure of the maximum amount of air that can be inhaled and exhaled in one minute, measured in liters/minute. | Note that functional residual capacity (FRC) cannot be measured via spirometry, but it can be measured with a plethysmograph. Vital capacity is the maximum volume of air that a person can exhale after maximum inhalation. ...
Vital capacity is the maximum volume of air that a person can exhale after maximum inhalation. ...
Functional Residual Capacity (FRC) is a medical term referring to the amount of air present in the lungs at the end of passive expiration. ...
A plethysmograph is an instrument for measuring changes in volume within an organ or whole body (usually resulting from fluctuations in the amount of blood or air it contains). ...
Results are usually given in both raw data (liters, liters per second) and percent predicted - the test result as a percent of the "predicted values" for the patients of similar characteristics (height, age, sex, and sometimes race and weight). The interpretation of the results can vary depending on the physician and the source of the predicted values. Generally speaking, results nearest to 100% predicted are the most normal, and results over 80% are often considered normal. However, review by a doctor is necessary for accurate diagnosis of any individual situation.
Technologies used in spirometers - Volumetric Spirometers
- Flow measuring Spirometers
- Fleisch-pneumotach
- Lilly (screen) pneumotach
- Turbine(actually a rotating vein, this spins, the revolutions are counted as they break a light beam)
- Pitot tube
- Hot-wire anemometer
- Ultrasound
A large bellows creates a mushroom cloud at the Exploratorium in San Francisco, California. ...
A Siemens steam turbine with the case opened. ...
A Pitot tube is a measuring instrument used to measure fluid flow. ...
A hemispherical cup anemometer of the type invented in 2000 by John Thomas Romney Robinson An anemometer is a device for measuring the velocity or the pressure of the wind, and is one instrument used in a weather station. ...
For other uses, see Ultrasound (disambiguation). ...
See also A peak flow meter is a small, hand-held device used to manage asthma by monitoring airflow through the bronchi and thus the degree of restriction in the airways. ...
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