Spirometry (meaning breath measurement ) is the most common lung function test (PFT). It measures lung function, especially the amount (volume) and/or air (stream) velocity that can be inhaled and exhaled. Spirometry is helpful in assessing breathing patterns that identify conditions such as asthma, pulmonary fibrosis, cystic fibrosis, and COPD. It also helps as part of the health surveillance system, where the breathing pattern is measured over time.
Spirometry produces pneumotachographs, a graph that plots the volume and flow of air in and out of the lungs from one inhalation and one breathing.
Video Spirometry
Indication
Spirometry is indicated for the following reasons:
- to diagnose or manage asthma
- to detect respiratory illness in patients with symptoms of breathlessness, and to differentiate respiration from heart disease as the cause
- to measure bronchial response in patients suspected of having asthma
- to diagnose and distinguish between obstructive pulmonary disease and restrictive lung disease
- to follow the natural history of the disease in respiratory conditions
- to assess the impairment of occupational asthma
- to identify those at risk from pulmonary barotrauma during scuba diving
- to perform pre-operative risk assessment prior to anesthesia or cardiothoracic surgery
- to measure response to treatment conditions that detect spirometry
- to diagnose vocal cords dysfunction.
Maps Spirometry
Contraindications
Forcible expiratory maneuvers can worsen some medical conditions. Spirometry should not be performed when an individual comes with:
- Hemoptysis of unknown origin
- Pneumothorax
- Unstable cardiovascular status (angina, recent myocardial infarction, etc.)
- Chest, stomach, or cerebral aneurysms
- Cataracts or recent eye surgery
- Recent chest or stomach surgery
- Nausea, vomiting, or acute illness
- Latest or recent virus infection
- Undiagnosed hypertension
Spirometry Test
Spirometer
Spirometry tests are performed using a device called a spirometer, which comes in several different varieties. Most spirometers display the following graph, called spirogram:
- a time-volume curve , denotes the volume (liters) along the Y axis and time (seconds) along the X axis
- the volume flow loop , which graphically depicts the airflow rate on the Y axis and the total volume that is inspired or expired on the X axis
Procedures
The vital volume vital capacity (FVC) test varies slightly depending on the equipment used, either closed circuit or open circuit, but must follow ATS/ERS Standardization of Spirometry.
Generally, the patient is asked to take the deepest breath possible, then exhale into the sensor as hard as possible, for as long as possible, preferably at least 6 seconds. Sometimes immediately followed by rapid inhalation (inspiration), especially when assessing the possibility of upper airway obstruction. Sometimes, the test will be preceded by a period of quiet breathing in and out of the sensor (tidal volume), or rapid breathing in (forced inspiration) will come before forced blowing.
During the test, a soft nose clip can be used to prevent air from passing through the nose. Funnel filters can be used to prevent the spread of microorganisms.
Test limits
Maneuver is highly dependent on patient cooperation and effort, and is usually repeated at least three times to ensure reproducibility. Because the result depends on the patient's cooperation, FVC can only be underestimated, never overdoing it.
Because patient co-operation is necessary, spirometry can be used only in older children to understand and follow the instructions given (6 years or more), and only in patients who are able to understand and follow instructions - thus, this test is not suitable for patients who are unconscious, very sedated, or have limitations that will interfere with strong breathing efforts. Other types of lung function tests are available for infants and unconscious persons.
Another major limitation is the fact that many patients with intermittent or mild asthma have a normal spirometry between acute exacerbations, limiting the usefulness of spirometry as a diagnostic. This is more useful as a monitoring tool: abrupt decrease in FEV1 or other spirometry measurements in the same patient may indicate a deteriorating control, even if the raw value is still normal. Patients are encouraged to record their personal best practices.
Related test
Spirometry can also be part of the bronchial challenge test, used to determine bronchial hyperresponsiveness for either strict exercise, breathing cold/dry air, or with pharmaceutical agents such as methacholine or histamine.
Sometimes, to assess the reversibility of certain conditions, a bronchodilator is administered before performing another test round for comparison. This is usually referred to as a reversibility test, or post-bronchodilatory test (PostBD), and is an important part of diagnosing asthma compared to COPD.
Other complementary lung function tests include plethysmography and nitrogen washing.
Parameters
The most common parameters measured in spirometry are Vital capacity (VC), Forced vital capacity (FVC), Forced expiratory volume (FEV) at 0.5, 1.0 (FEV1), 2.0 and 3.0 second intervals , forced expiratory flow 25-75% (FEF 25-75) and maximum voluntary ventilation (MVV), also known as maximum breathing capacity. Other tests can be done in certain situations.
Results are usually given in raw data (liter, liters per second) and percent-test prediction as a percent of "predicted value" for patients with similar characteristics (height, age, sex, and sometimes race and weight). ). Interpretation of results may vary depending on the doctor and the source of predicted values. In general, a near 100% predicted result is the most normal, and results over 80% are often considered normal. Some prediction value publications have been published and can be calculated online by age, gender, weight and ethnicity. However, examination by a physician is necessary for an accurate diagnosis of each individual situation.
Bronchodilators are also given under certain circumstances and pre/post chart comparisons are performed to assess the effectiveness of bronchodilators. See sample prints.
The functional residual capacity (FRC) can not be measured through spirometry, but can be measured by plethysmograph or dilution tests (eg, helium dilution test).
Kapasitas vital paksa (FVC)
Forced vital capacity (FVC) is the volume of air that can be forcibly destroyed after full inspiration, measured in liters. FVC is the most basic maneuver in spirometry tests.
Forced expiration volume in 1 second (FEV1)
FEV1 is the volume of air that can be forcibly destroyed in one second, after full inspiration. The mean value for FEV1 in healthy people is highly dependent on gender and age, according to the diagram on the left. The value between 80% and 120% of the average value is considered normal. Predicted normal values ​​for FEV1 can be calculated online and depending on age, sex, height, mass and ethnicity as well as research studies based on them.
ratio FEV1/FVC (FEV1%)
FEV 1 /FVC (FEV1%) is the FEV ratio 1 to FVC. In healthy adults it should be around 70-85% (decreases with age). In obstructive diseases (asthma, COPD, chronic bronchitis, emphysema) FEV 1 decreases due to increased airway resistance to expiratory flow; FVC may decrease as well, since premature airway closure is in expiration, just not in the same proportion as FEV 1 (eg, both FEV 1 and FVC is reduced, but the first more affected due to increased airway resistance). This results in a reduced value (& lt; 80%, often ~ 45%). In restrictive diseases (such as pulmonary fibrosis) FEV 1 and FVC are both proportionately reduced and their values ​​may be normal or even increased as a result of decreased lung compliance.
The FEV1% derivative value is FEV1% predicted , defined as FEV1% of patients divided by mean FEV1% in the population for each person with the same age, height, sex, and race..
Forced expiration (FEF)
Forced expiratory flow (FEF) is the flow (or velocity) of air coming out of the lungs during the middle of forced expiration. This can be given at discrete time, generally determined by the fractional remains of vital force capacity (FVC). The usual intervals are 25%, 50% and 75% (FEF25, FEF50 and FEF75), or 25% and 50% of FVC. It can also be given as an average flow over a period of time, also generally limited by a fixed specific fraction of FVC, typically 25-75% (FEF25-75%). The average range in a healthy population depends primarily on gender and age, with FEF25-75% indicated in the diagram on the left. Values ​​ranging from 50-60% and up to 130% of the average are considered normal. Normal value predictions for FEF can be calculated online and depending on age, sex, height, mass and ethnicity as well as research studies based on them.
MMEF or MEF stands for maximal (middle) expiratory flow and is the peak of the expiratory stream taken from the volume-flow curve and measured in liters per second. Theoretically it should be identical to peak expiratory flow (PEF), which, however, is generally measured by peak flow meters and is given in liters per minute.
Recent studies have shown that FEF25-75% or FEF25-50% may be a more sensitive parameter than FEV1 in detecting obstructive small airway disease. However, in the absence of concurrent changes in standard markers, differences in mid-range expiratory flow may not be specific enough to be useful, and current practice guidelines recommend continuing to use FEV1, VC, and FEV1/VC as indicators of obstructive disease..
More rarely, forced expiratory flow can be given at intervals determined by how much residual lung capacity total. In such cases, it is usually set as mis. FEF70% TLC, FEF60% TLC and FEF50% TLC.
Forced inspiration flow 25-75% or 25-50%
A forced inspiration flow of 25-75% or 25-50% (FIF 25-75% or 25-50%) is similar to FEF 25-75% or 25-50% unless measurements are made during inspiration.
Peak expiratory flow (PEF)
Peak expiratory flow (PEF) is the maximum flow (or speed) achieved during maximum forced expiration that begins at full inspiration, measured in liters per minute or in liters per second.
Volume tidal (TV)
Tidal volume is the amount of air inhaled or exhaled normally at rest.
Total pulmonary capacity (TLC)
Total lung capacity (TLC) is the maximum volume of air present in the lungs
Diffusing Capacity (DLCO)
Diffusing capacity (or DLCO) is carbon monoxide uptake from one inspiration in standard time (usually 10 seconds). During the test, one inhales a test gas mixture comprising ordinary air covering an inert gas and CO gas, less than one percent. Since hemoglobin has a greater affinity for CO than oxygen, then the breath holding time is only 10 seconds, which is the amount of time sufficient for this CO transfer to occur. Since the amount of CO inhalation is known, the exhaled CO is reduced to determine the amount transferred during the time of breath holding. The gas tracer is analyzed simultaneously with CO to determine the distrubsi of the test gas mixture. This test will take on diffusion difficulties, for example in pulmonary fibrosis. This should be corrected for anemia (low concentrations of hemoglobin will reduce DLCO) and pulmonary hemorrhage (excess RBC in the interstitium or alveoli can absorb CO and artificially increase the capacity of DLCO). The atmospheric pressure and/or altitude will also affect the measured DLCO, so a correction factor is needed to adjust the standard pressure. An online calculator is available to correct hemoglobin levels and altitude and/or pressure at which measurements are made.
Maximum voluntary ventilation (MVV)
Maximum voluntary ventilation (MVV) is a measure of the maximum amount of air that can be inhaled and exhaled in one minute. For the convenience of this patient is performed for a period of 15 seconds before extrapolating to a value for one minute expressed as liter/min. The average value for men and women is 140-180 and 80-120 liters per minute.
Static lung compliance (C st )
When estimating static lung compliance, the volume measurements by the spirometer should be equipped with a pressure transducer to simultaneously measure transpulmonary pressure. When drawing a curve with the relationship between volume changes to changes in transpulmonary pressure, C st is the slope of the curve over a certain volume, or, mathematically,? V/? P. The fulfillment of static lung may be the most sensitive parameter for detecting abnormal pulmonary mechanics. It is considered normal if 60% to 140% of the mean value in the population for each person with the same age, sex and body composition.
In those with acute respiratory failure in mechanical ventilation, "static compliance of the conventional total breathing system is obtained by dividing the tidal volume by the difference between" plateau "pressure measured at the opening of the airway (PaO) during end-inspiration and expiratory pressure positive end (PEEP) defined by the ventilator ".
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Expedited Expansion Time (FET)
The Forced Expiratory Time (FET) measures the length of the expiration in seconds.
Slow vital capacity (SVC)
Slow vital capacity (SVC) is the maximum volume of air that can be exhaled slowly after the slowest inhalation.
Maximum pressure (P max and P i )
P max is the maximum asymptotic pressure that can be developed by the respiratory muscles in lung volume and P i is the maximum inspiratory pressure that can be developed at a particular lung volume. This measurement also requires a pressure transducer in addition. It is considered normal if 60% to 140% of the mean value in the population for each person with the same age, sex and body composition. A derived parameter is the coefficient retraction (CR) which is P max /TLC.
Average transit time (MTT)
The average transit time is the area under the volume-flow curve divided by the vital capacity of force.
Maximum inspiratory pressure (MIP) MIP, also known as negative inspiration (NIF) , is the maximum pressure that can be generated of clogged airways beginning with functional residual capacity (FRC). It is a marker of respiratory muscle function and strength. Represented by centimeter water pressure (cmH2O) and measured by manometer. Maximum inspiratory pressure is an important and noninvasive diaphragm strength index and an independent tool for diagnosing many diseases. The maximum typical inspiratory pressure in adult men can be estimated from the equation, M IP = 142 - (1.03 x Age) cmH 2 O, where age is within a few years.
Technology used in spirometer
- Volumetric Spirometer
- Water bell
- Bellow wedge
- Flow measuring Spirometer
- Fleisch-pneumotach
- Lilly (screen) pneumotach
- Turbine/Rotor Stator (usually not mistakenly referred to as a turbine.Actually a rotating blade that rotates due to the airflow generated by the subject.The revolution of a propeller is calculated as they break the light)
- The pitot tube
- Hot wire anemometer
- Ultrasound
See also
- Peak flow meter
- Nitrogen Wash
References
Further reading
Miller MR, Crapo R, Hankinson J, Brusasco V, Burgos F, Casaburi R, Coates A, Enright P, van der Grinten CP, Gustafsson P, Jensen R, Johnson DC, MacIntyre N, McKay R, Navajas D, Pedersen OF, Pellegrino R, Viegi G, Wanger J (July 2005). "General considerations for pulmonary function testing". European Respiratory Journal . 26 (1): 153-161. doi: 10.1183/09031936.05.00034505. PMIDÃ, 15994402.
External links
- American Thoracic Society (ATS)
- European Respiratory Society (ERS)
Source of the article : Wikipedia
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