Vital Capacity (VC = Vital Capacity) - vital capacity of the lungs(the volume of air that leaves the lungs when exhaling as deeply as possible after inhaling as deeply as possible)
IRV = inspiratory reserve volume - reserve volume inhalation(extra air) is the volume of air that can be inhaled during a maximum inhalation after a normal inhalation
ROvyd (ERV = Expiratory Reserve Volume) - expiratory reserve volume(reserve air) is the volume of air that can be exhaled during a maximum exhalation after a normal exhalation
EB (IC = inspiratory capacity) - inhalation capacity- actual sum of tidal volume and inspiratory reserve volume (EB = DO + ROvd)
OZL (TV = tidal volume) - lung closure volume
FOEL (FRC = functional residual capacity) - functional residual capacity of the lungs. This is the volume of air in the lungs of a patient at rest, in a position where normal exhalation is completed and the glottis is open. FOEL is the sum of the expiratory reserve volume and residual air (FOEL = ROV + OB). This parameter can be measured using one of two methods: helium dilution or body plethysmography. Spirometry does not measure FUEL, so the value of this parameter must be entered manually.
OV (RV = residual volume) - residual air(another name is RVL, residual lung volume) is the volume of air that remains in the lungs after maximum exhalation. Residual volume cannot be determined using spirometry alone; this requires additional measurements of lung volume (using the helium dilution method or body plethysmography)
TLC (TLC = total lung capacity) - total lung capacity(the volume of air in the lungs after taking the deepest breath possible). VEL = vital capacity + ov
FVC = FVC (FVC = forced vital capacity)- (Tiffno sample). Forced vital capacity of the lungs is the volume of air exhaled during the fastest and most powerful exhalation.
FEV05 (FEV05 = forced expiratory volume in 0.5 sec)- forced expiratory volume in 0.5 seconds
FEV1 (FEV1 = forced expiratory volume in 1 sec)- forced expiratory volume in 1 second - the volume of air exhaled during the first second of forced expiration.
FEV3 (FEV3 = forced expiratory volume in 3 sec)- forced expiratory volume in 3 seconds
OFVpos = Opos = OPOS (FEVPEF)- volume of forced expiration at which POS is achieved (peak volumetric flow rate)
MOS25 (MEF25 = FEF75 = forced expiratory flow at 75%) - instantaneous volumetric velocity after exhalation 25% FVC, 25% are counted from the beginning of exhalation
MOC50 (MEF50 = FEF50 = forced expiratory flow at 50%)- instantaneous volumetric velocity after exhalation 50% FVC, 50% are counted from the beginning of exhalation
MOS75 (MEF75 = FEF25 = forced expiratory flow at 25%)- instantaneous volumetric velocity after exhalation 75% FVC, 75% counted from the beginning of exhalation
SOS25-75 (MEF25-75)- average volumetric velocity in the range between 25% and 75% FVC
SOS75-85 (MEF75-85)- average volumetric velocity in the range between 75% and 85% FVC
SOS0.2-1.2- average volumetric flow rate between 200 ml and 1200 ml expiratory FVC
POS = POSvyd = PSV(peak expiratory flow) (PEF = peak expiratory flow)- peak expiratory volumetric flow rate
MPP (MMEF = maximal mid-expiratory flow)- maximum semi-exhaled flow
TFVC = Input = Tout (E_TIME = expiratory time)- total expiratory time FVC
TFVC = Inspiratory time = Tvd (I_TIME = inspiratory time)- total inspiratory time FVC
TFZHEL/TFZHELVd- ratio of exhalation time to inhalation time
TPOS = TPOS (TPEF)- time required to reach peak expiratory flow rate
STV (mean transit time) = SPV (mean transition time) = MTT (mean transition time)- the value of this time is located at the point, the perpendicular from which forms two figures of equal area with the spirographic curve
FVC (FIVC = FVCin = forced inhaled vital capacity)- forced vital capacity of the lungs inhalation
FEV05vd (FIV05 = forced inspiratory vital capacity in 0.5 sec)- volume of forced inspiration in 0.5 seconds
FEV1vd (FIV1 = forced inspiratory vital capacity in 1 sec)- volume of forced inspiration in 1 second
FEV3vd (FIV3 = forced inspiratory vital capacity in 3 sec)- volume of forced inspiration in 3 seconds
PIF = peak inspiratory flow- peak inspiratory volumetric flow rate
FVC (FIVC = FVCin = forced inspiratory vital capacity)- forced vital inspiratory capacity
MOS50vd (MIF50)- instantaneous volumetric velocity at the moment of reaching 50% of the inspiratory FVC volume, 50% is counted from the beginning of inspiration
PSA (BSA = body surface area)- body surface area (m2)
IT = FEV1/VC (FEV1/VC = Index Tiffeneau)- Tiffno index
IG = FEV1/FVC (FEV1/FVC = Index Gaenslar)- Genslar index
FEV3/FVC- ratio of FEV3 to FVC
FEV1vd/FVC (FIV1/FVC)- ratio of FEV1vd to FVC
FEV1/FVC (FIV1/FIVC)- ratio of FEV1vd to FVC
FEV1/FEV1vd (FEV1/FIV1)- ratio of FEV1 to FEV1wd
MOS50/FVC (MIF50/FVC)- the ratio of the instantaneous volumetric velocity at the moment of reaching 50% of the expiratory FVC volume to the forced vital capacity of the expiratory lungs
MOS50/ZHEL (MEF50/VC)- the ratio of the instantaneous volumetric velocity at the moment of reaching 50% of the expiratory FVC volume to the vital capacity of the expiratory lungs
MOS50/MOS50vd (MEF50/MIF50)- the ratio of the instantaneous volumetric velocity at the moment of reaching 50% of the expiratory FVC volume to the same parameter during inspiration
Avyd (Aex = AEFV)- area of the expiratory part of the flow-volume curve
Avd (Ain = AIFV)- area of the inspiratory part of the flow-volume curve
A- total area of the flow-volume loop
MVV (MVV = maximum voluntary ventilation)- maximum ventilation of the lungs (ventilation limit) is maximum volume air passing through the lungs during forced breathing in one minute
OV MVL (TV MVV)- the volume of air passing through the lungs when performing the MVV test (MVL) in one inhalation-exhalation.
RR (RR = respiration rate)- respiratory rate during MVL
PSDV = MVL/VC- air movement capacity
MOD (LVV = low voluntary ventilation) - minute volume respiration is the volume of air passing through the lungs during normal breathing in one minute.
OB MOD = DO (tidal volume, average) = (TV LVV)- the volume of air passing through the lungs when performing the MOD test (LVV) in one inhalation-exhalation.
RR (RR = respiration rate)- respiratory rate at MOD
These parameters are basic. Total quantity There are usually more measured parameters, since it includes various combinations of basic parameters.
This survey measures all the parameters mentioned above.
Function external respiration has an important diagnostic value. To measure it, a special technique is used that evaluates the speed and unlimited flows in the airways, capacities, and volumes of the lungs. The Tiffno index and other spirography indicators become important in identifying such severe pathologies respiratory system, like COPD, asthma.
The normal numbers of the Tiffno index are the ratio of 2 values: FEV1 and FVC.
Forced expiratory volume or FEV1 - quantity atmospheric air, which a person exhales in the first second, making maximum effort (the deepest exhalation). If this figure is less than 1 liter, diagnostic test ineffective.
Forced vital capacity, or FVC, is all the air a person exhales after
Tiffno formula = (FVC/FEV1)×100%
The index determines the severity of tracheobronchial obstruction:
The test that determines the Tiffno index is an accessible and simple method that objectively assesses the impairment of the capacity of the trachea and bronchi. With its help, the origin (pathogenesis) of obstruction and the dynamics of pulmonary ventilation are studied. The test is carried out under the influence of functional loads, as well as with the use of bronchodilators of different mechanisms of action (pharmacological test).
With obstruction in the respiratory system, resistance to air circulation increases. This is expressed already at the beginning of the release of gases from the lungs, and progresses towards the end of the act. The more the ventilation is impaired, the lower the vital capacity. One of the first to discover this pattern was the French doctor Tiffno. He developed a diagnostic method to assess the degree of airway obstruction. To standardize the technique, Tiffno proposed recording FVC in the first second of forced expiration (FVC1s). FVC is normally 70-80%.
The purpose of the examination is to measure the relative and absolute volume of forced expiration. These will be indicators of the aerodynamic resistance of the respiratory tract.
To carry out the diagnostic procedure, a spirometer or spirograph is used. You will also need a nose clip, rubbing alcohol, and cotton wool.
The object of study is the patient.
Work algorithm:
In patients under 50 years of age, in the absence of chronic diseases of the respiratory system, FEV1 is 70-80%. In older people, the figure drops to 65-70%. With chronic bronchial obstruction, aerodynamic resistance increases and exhalation lengthens. The relative FEV1 decreases.
Spirometry is a technique for studying the functions of a person’s external physiological respiration, as well as identifying deviations indicating pathology of the bronchopulmonary system.
Types of spirometry tests:
All air measurements are carried out using a spirometer - a small portable device that records 26 modes and parameters of external respiration. The device has a numeric keypad for entering the patient's date of birth, height, and weight. A tube is attached to the device, into which the patient breathes at the doctor’s command. After the measurements are taken, a sheet is printed on which the test results and a graphical representation of the dynamics of breathing are indicated.
Indications for spirometry:
Breathing is not assessed in a state of severe intoxication of the body, with high body temperature, suffocating cough. These symptoms prevent the test from being carried out efficiently and reliably. Diagnosis is contraindicated for pregnant women with toxicosis, as well as throughout the second half of pregnancy.
The spirometry technique is contraindicated if the patient has a history of the following serious illnesses:
In addition to the Tiffno index, the condition of the lungs is comprehensively assessed during diagnosis.
Other basic spirometry indicators:
Spirometry is performed in the clinic. The results are interpreted in accordance with the clinical characteristics and patterns of development of pathological processes. It is important to remember that the reliability of the test depends on correctly taking a deep breath and sequential forced exhalation. To avoid mistakes, the patient is given instructions before performing the procedure.
The respiratory rate (RR) is determined by the number of respiratory cycles recorded in one minute, which corresponds to a 50 mm horizontal segment of the spirogram. Normally, in a healthy adult, the number of respiratory movements is 16-20 per minute. RR depends on gender, age, profession, body position during the study. A physiological increase in breathing is observed during physical activity, emotional arousal, and after a heavy meal.
An increase in respiratory rate in pathological conditions is observed:
a) with a decrease in the respiratory surface of the lungs: pneumonia, tuberculosis, collapse (atelectasis) of the lung due to its compression from the outside by liquid or gas, pneumosclerosis, fibrosis, pulmonary embolism, pulmonary edema;
b) with insufficient depth of breathing: difficulty contracting the intercostal muscles or the diaphragm when sharp pain occurs (dry pleurisy, acute myositis, intercostal neuralgia, fractured ribs, development of tumor metastases in the ribs); a sharp increase in intra-abdominal pressure and a high standing of the diaphragm (ascites, flatulence, late pregnancy, hysteria).
Pathological decrease in breathing observed when the respiratory center is depressed and its excitability is reduced (brain tumors, meningitis, cerebral hemorrhage, cerebral edema), when the respiratory center is exposed to toxic products due to their significant accumulation in the blood (uremia, hepatic coma, diabetic coma, some infectious diseases) , with obstructive processes (bronchial asthma, chronic obstructive bronchitis, pulmonary emphysema).
Definition of DO(tidal volume) - the volume of air inhaled or exhaled during each normal respiratory cycle. The height of the respiratory wave is determined in millimeters and multiplied by the scale of the spirograph (20 or 40 ml depending on the type of spirograph). Normally, DO is 300-900 ml (average 500 ml).
A decrease in RR is usually combined with an increase in RR, and an increase in RR is usually combined with a decrease in RR (see reasons above). However, sometimes there can be a simultaneous decrease in DO and RR (sparse shallow breathing) with a sharp depression of the respiratory center, severe emphysema, a sharp narrowing of the glottis or trachea, or a simultaneous increase in DO and an increase in RR with high fever, severe anemia.
Determination of minute volume of respiration (MVR)
Amount of ventilated air per 1 min. MOD is determined by multiplying DO by breathing frequency: MOD (l) = DO (ml) x RR. If the respiratory waves are unequal, then the MRR is determined by summing up the DO in one minute. Normally, MOD ranges from 4-10 liters (average 5 liters). MVR is a measure of pulmonary ventilation, but not an absolute indicator of the effectiveness of alveolar ventilation; depends on the DO, BH and the amount of dead space. With the same MOP, alveolar ventilation can be different: frequent and shallow breathing is less rational, since a significant part of the inhaled air ventilates only the dead space without entering the alveoli, effective alveolar ventilation is reduced. With the same MOD indicators, but with slow and deep breathing, effective alveolar ventilation is much higher. Thus, the determination of the MRR, frequency and depth of breathing and the comparison of these indicators with each other and over time becomes of practical importance.
Determination of the proper MOD (DMOD)6 carried out according to the formula A.G. Dembo. The calculation is based on the proper basal metabolic rate, which is found using the table of Harris and Benedict. First, calculate DPO 2 using the formula: DPO 2 = DPO: 7.07 (coefficient 7.07 is the product of the thermal equivalent of 1 liter of oxygen, equal to 4.9, by the number of minutes per day - 1440 and divided by 1000). DMOD=DPO 2:40. Under normal conditions, 40 ml of oxygen is absorbed from every liter of ventilated air. MOD depends on the deterioration of the use of ventilated air, the difficulty of normal ventilation, disruption of gas diffusion processes, the body's need for O 2, and the intensity of metabolic processes.
MAUD increases:
a) when the body’s need for oxygen increases (degrees I and II of pulmonary and heart failure);
b) with an increase in metabolic processes (thyrotoxicosis);
c) with certain lesions of the central nervous system.
MOD decreases:
a) in case of severe III degree pulmonary or heart failure due to depletion of the body’s compensatory capabilities;
b) with a decrease in metabolic processes (myxedema);
c) when the respiratory center is depressed.
Determination of inspiratory reserve volume (IRV) - the maximum volume of air that a person can inhale after a normal breath. The height of the maximum inhalation wave (in mm) is measured from the level of quiet breathing and multiplied by the scale of the spirograph scale. Normal Department of Internal Affairs. equal to 1500-2000 ml. ROVD.= 45-55% VEL. The value of ROVD is of great practical importance. does not, since in healthy individuals it is subject to significant fluctuations. District Department of Internal Affairs decreases with a decrease in the respiratory surface of the lungs and in the presence of reasons that interfere with the maximum expansion of the lungs.
Determination of expiratory reserve volume (ERV) - the maximum volume of air that can be exhaled after a quiet exhalation. The magnitude of the maximum exhalation wave (in mm) is measured from the level of quiet exhalation and multiplied by the scale of the spirograph scale. Normal ROvyd. equal to 1500-2000 ml. ROvyd. is approximately 25-35% vital capacity. Due to significant variability, this indicator does not have much practical significance. Significant reduction in ROvyd. observed in obstructive processes (pulmonary emphysema, bronchial asthma, chronic obstructive bronchitis). With stenotic breathing, the proportion of ROvyd. in vital capacity increases.
Determination of vital capacity of the lungs (VC) - the maximum amount of air that can be exhaled after a maximum inhalation. VIC is the sum of DO, ROvd. and ROvyd. Vital = BEFORE + ROVD. + ROvyd.
When determining vital capacity using a spirogram, the distance from the top of the inspiratory knee (maximum inspiration) to the top of the expiratory knee (maximum exhalation) is measured in millimeters and multiplied by the scale of the spirograph. Normally, vital capacity ranges from 3000 to 5000 ml. Its value depends on age (up to 35 years it grows, then gradually decreases), gender (in women, vital capacity indicators are lower than in men), height, body weight, and body position. To correctly assess the results, it is necessary to determine the ratio of actual to expected vital capacity (VCL). To determine JEL, use the formulas:
JEL in l = 0.052xP-0.028xB-3.20 (for men);
VEL in l = 0.049xP-0.019xB-3.76 (for women);
where P is height, B is age.
The deviation of VC from VC should not exceed 15%. Therefore, it is of practical importance to reduce vital capacity below 85% of the expected value.
Vital capacity decreases:
a) in pathological conditions that prevent maximum expansion of the lungs (exudative pleurisy, pneumothorax);
b) when the area of functioning pulmonary parenchyma decreases, which is associated with changes in the lung tissue itself (pulmonary tuberculosis, pneumonia, pulmonary fibrosis, lung abscess, atelectasis, etc.);
c) when the elastic framework of the lungs is depleted (emphysema);
d) with extrapulmonary pathology: processes that limit the expansion of the chest (kyphoscoliosis, ankylosing spondylitis), limited mobility of the diaphragm, increased intra-abdominal pressure (ascites, flatulence, etc.);
e) for diseases of the cardiovascular system in the presence of congestion in the pulmonary circulation;
f) with severe general weakness;
g) in case of violation of the functional state of the nervous system.
The diagnostic value of vital capacity in a single study cannot be considered sufficient, however, in a complex study of respiratory function, this indicator is very important both for calculations and comparison with other values, and for assessing the degree and type of respiratory failure (RF).
Determination of forced vital capacity (FVC) - the volume of air that can be exhaled after a maximum inhalation at the maximum possible speed. This indicator characterizes bronchial patency, elastic properties of the lungs, and the functionality of the respiratory muscles. Recording is performed at the maximum tape advance speed (600 mm/min or 1200 mm/min).
The FVC curve consists of two parts. The first part, which is recorded from the very beginning of exhalation, is characterized by a fast linear stroke and corresponds to the maximum and constant exhalation speed. Then the exhalation rate slows down, the curve becomes less steep and acquires a curvilinear course. The straight course of the FVC curve is caused by exhalation due to the elasticity of the lung tissue. Curvilinear vital capacity corresponds to the increasing force of the expiratory muscles.
FVC is determined by measuring the height of the curve from the top to its deepest part (in mm), followed by multiplication by the scale of the spirograph. Normally, FVC is 8-11% (100-300 ml) less than VC, mainly due to an increase in resistance to air flow in the small bronchi. If bronchial obstruction is impaired and air flow resistance increases, the difference increases to 1500 ml or more. This is observed in bronchial asthma, chronic obstructive bronchitis, and emphysema.
Determination of forced expiratory volume in 1 second (FEV 1) - the volume of air that the subject can exhale in the first second of a maximally forced exhalation. To determine this indicator on the FVC spirogram, from the zero mark corresponding to the beginning of exhalation, a segment equal to 1 second is set aside (1 cm at a tape pulling speed of 600 mm/min or 2 cm at a tape drive speed of 1200 mm/min). From the end of this segment it descends perpendicular to the intersection with the FVC curve, measure the height of the perpendicular in mm and multiply by the scale of the spirograph scale,
Normally, FEV 1 ranges from 1.4 to 4.2 l/sec. For a more correct assessment of the results, the ratio of actual FEV 1 to expected FEV 1 (DOFV 1) is determined. To calculate DOFV 1, the following formulas are used:
DOFV 1 =0.36xP-0.031x6-1.41 (for men);
DOFV 1 =0.026xP-0.028xB-0.36 (for women).
A decrease in FEV 1 below 75% DOFV 1 is of practical importance. The diagnostic significance of FEV 1 approximately corresponds to the significance of vital capacity, however, FEV 1 decreases to a greater extent during obstructive processes.
Definition of the Votchal-Tiffneau test. This indicator represents the relative one-second capacity, the percentage of FEV 1 to VC.
Tiffno test = FEV 1 / VC x 100%
Normally, the Tiffno test averages 70-90%. A decrease in the Tiffno test below 70% is considered pathological. The Tiffno test is of great importance in identifying obstructive processes in the lungs and is sharply reduced in bronchial asthma and emphysema.
To identify the role of bronchospasm in the occurrence of respiratory failure and reduce these indicators, pharmacological tests with bronchodilators (aminophylline, adrenaline, ephedrine, etc.) are used. FVC is recorded before and after administration of bronchodilators. If there are phenomena of bronchospasm after the administration of bronchodilators, the one-second capacity increases.
Determination of maximum pulmonary ventilation (MVL):(breathing limit, maximum tidal capacity, maximum minute volume).
MVL is the maximum amount of air that can be ventilated within a minute. Characterizes the functional ability of the external respiration apparatus.
Definition of MVL:
a) calculate the RR at maximum ventilation of the lungs (in 15 seconds), multiply this value by 4 and thus determine the RR during mechanical ventilation for 1 min;
b) determine DO at maximum ventilation. To do this, measure the size of the respiratory cycle in millimeters and multiply it by the spirograph scale;
c) multiply the BH by the DO (with MVL)
MVL in l = RR at MVL x DO at MVL.
Normally, MVL is in the range of 50-180 liters per minute. Its magnitude depends on the gender, age, height of the person being studied, and body position. To correctly assess the results obtained, it is necessary to bring the actual MFL to the proper one. For calculations use the formulas:
DMVL=JELx25 (for men);
DMVL=JELx26 (for women).
It is of practical importance to reduce the MVL below 75% of the expected value. MVL depends on muscle strength, compliance of the lungs and chest, and resistance to air flow. Its decrease is observed in processes accompanied by a decrease in lung compliance and impaired bronchial conduction. MVL decreases in various lung diseases and heart failure. Its decrease increases as pulmonary or heart failure progresses. MVL is an indicator that subtly reacts to the state of the nervous system.
Determination of respiratory reserve (RR)
Breathing reserve indicates how much the patient can increase ventilation.
RD in l = MVL-MOD
RD in %DMVL = RD/MVL x 100%
RD in % MVL is one of the valuable indicators of the functional state of the external respiration apparatus. Normally, RD = 70-80 liters and exceeds MOD by no less than 15-20 times. RD=85-95% MVL.
RD decreases with respiratory and heart failure to 60-55% and below.
Related information.
For normal functioning, the human body needs air.
Saturating cells with oxygen is the main purpose of the respiratory organs.
The volume of air inhaled is important in determining the level of lung function. For this type of research, there is spirometry.
What it is, for what purpose, how it is carried out and when its purpose is excluded will be discussed later in the article.
The term is formed from two words: spiro– breathing and geometry- measurements, measurements.
Spirometry– diagnostic examination of external respiration function with the establishment of characteristic speed and volume indicators.
The method is widely used in medicine: it allows identifying pathologies that cause respiratory dysfunction and low levels of gas exchange.
The procedure is painless and harmless. The measurements are based on inhalation and exhalation rates and lung capacity.
The procedure is carried out with a special digital device - a spirometer. Their mechanism is quite simple: an air flow sensor and a computing part that converts information into numerical values.
The readings are calculated automatically. There are computer modifications of the device.
Electronic spirometer MSA99 The first examinations were carried out with mechanical (most often water) spirometers. All indicators were calculated manually. The procedure was long and laborious.
If constant monitoring is necessary, you can use a modern portable spirometer, which is applicable both at home and when traveling.
Consultations with your attending physician and a medical specialist who sells similar equipment will help you choose the right device. A spirometer is selected taking into account functional requirements and personal preferences.
The most accurate measurements are provided by a special camera with sensors - plethysmograph. The results of the study, presented graphically in the form of spirography, help to clearly illustrate modifications in human lung volume during normal and forced breathing. What is spirography and what it looks like can be clearly seen in the figure:
Rice. 1 Spirography Through the procedure:
Measurements are carried out on an outpatient basis with immediate results.
There are a number of indications for prescribing the procedure. Diagnostics is carried out for the purpose of:
Persons over 40 years of age, smokers for 10 years or more, with a chronic cough or examination are mandatory.
Preventive medical measures are recommended for workers associated with the regular use of harmful chemicals.
Spirometry has no strict contraindications. Mild dizziness, which may occur, passes quickly and does not pose a health hazard.
Forced or strong deep inspiration causes a short-term increase in intracranial and intra-abdominal pressure.
The procedure should be performed with caution or abandoned for the following indications:
Even in the absence of obvious contraindications, consultation with a specialist is necessary before the study.
The way the procedure is performed determines its type. Spirometric tests are performed during the following maneuvers:
Modern spirometers make it possible to determine the level of diffusion capacity of the lungs - the gas exchange of oxygen and carbon dioxide between the respiratory organs and the blood.
Additional examination - bronchospirometry. Allows you to separately record indicators in different lobes of the lungs.
Preparation for spirography is very important. The reliability of the results obtained is increased by observing the following rules:
Before starting the study, the medical professional must find out the patient’s data (height, weight) and enter their device, select the spirometer by size, help the patient take the desired position and explain the sequence and rules for performing breathing maneuvers.
The patient is in a comfortable position, arms are relaxed on the armrests. To ensure only mouth breathing, the nose is blocked with a special clip. A tube with a disposable sterile tip (mouthpiece) is inserted into the mouth. At the beginning of the procedure, the patient breathes naturally and evenly.
The indicator DO is determined - tidal volume. The patient is then asked to take a normal breath and exhale all the air as quickly as possible. This will be the indicator of expiratory reserve volume (ERV).
The duration of exhalation with maximum effort of more than 15 seconds is a reason to diagnose pathology. Then the maximum breathing capacity is measured.
You should inhale as deeply as possible (reserve inspiratory volume - ROVD and vital capacity of the lungs - VC are recorded) and rapidly exhale (FEV and FVC are determined).
The device automatically builds a graph based on the measurement readings. FEV indicators have diagnostic significance.
The shape of the loop shown allows you to diagnose the type of respiratory failure:
The reversibility of obstruction is determined by the data of a test with bronchodilators. FEV readings are of primary comparative importance.
Each test is carried out several times (usually 3 times). After this, the most successful ones are selected.
The device produces the result of a spirogram, based on which the doctor evaluates a specific case and makes a conclusion. The procedure takes about 15 minutes. How many times and with what frequency the diagnosis is carried out is determined by the treating pulmonologist according to the indications.
The result of the examination is assessed according to the following indicators:
Table 1. Abbreviated designation and characteristics of spirometric study indicators.
| Reduction | Name | The essence of the indicator |
| TO | tidal volume | volume of air inhaled or exhaled during each respiratory act |
| vital capacity | vital capacity | the maximum volume of air that can be exhaled during a maximum inhalation (VC= ROvd+ DO+ ROind) |
| OO | residual volume | volume of air remaining in the lungs after maximum exhalation |
| District Department of Internal Affairs | inspiratory reserve volume | the maximum volume of air that can be inhaled after a normal breath |
| ROvyd | expiratory reserve volume | the maximum volume of air that can be exhaled at the end of a normal exhalation |
| FVC | forced vital capacity | the volume of air that can be forcefully exhaled quickly after a maximum inhalation |
| EV | inspiratory capacity | the maximum volume of air that can be inhaled after normal exhalation (EV = ROvd + DO) |
| OFO | residual functional volume | the volume of air that remains in the lungs after normal exhalation (OFO = ROvyd + OO) |
| OEL | total lung capacity | volume of air in the lungs after maximum inspiration (OEL=DO+ROVD) |
| OO/OEL | residual volume/total lung capacity | percentage of residual volume and total lung capacity |
From the age of 9, a full examination is possible along with adults. Young patients should be diagnosed in specialized institutions for children.
Creating a relaxed atmosphere is the key to successful spirometry. A worker with a pedagogical approach and the use of a playful form has greater authority in the eyes of the child and will be able to carry out the procedure most effectively.
The meaning of the event and its actions are explained to the child. Thematic pictures can be used to help the child understand what is required. For example, blowing out a candle.
The specialist must pay attention to the correct execution of maneuvers and the correct sealing of the tube with the lips. The protocol reflects the number of successfully completed tests. When forming a conclusion, the patient’s age is taken into account.
There are certain norms of indicators, based on which the doctor draws conclusions.
Interpretation of the results of physical activity should take into account gender anatomical differences, age-related changes, previous diseases, and type of work activity.
Indicators will be differentiated for a healthy person and a patient. Formulas for calculating the norm are given in the table:
Table 2. Formulas for calculating normal spirometry readings
Note. When using a SG spirometer, the required FEV1 decreases in men by 0.19 l, in women - by 0.14 l. In persons aged 20 years, vital capacity and FEV are approximately 0.2 l less than at the age of 25 years; for persons over 50 years of age, the coefficient when calculating the proper international level is reduced by 2.
The norm will be individual for each person. Main spirometric parameters: FEV1, VC, FVC, FEV1/FVC. The results are analyzed based on the maximum values of FVC and FEV1.
The interpretation of the data obtained should be concise, clear, and complete. The specialist not only determines deviations of indicators from the standard value, but also evaluates the overall picture, analyzing their entirety in interrelation.
All indicators are presented below:
Table 3. Spirometry indicators
The Tiffno test is informative in assessing pathological abnormalities. To understand the degree of deviation from the norm, it is customary to determine the percentage. Depending on the decrease in readings, the severity of pathological abnormalities increases.
A reading of 70% for the FEV1/FVC ratio results in significant false-positive results; a reading of 80% is also often misinterpretable in adults, but is acceptable in children. For older people (over 70 years old), some experts recommend using a value of 65%.
Carrying out the procedure with a high-quality spirometer will avoid distortions and obtain reliable readings.
Correct interpretation of the results of respiratory function helps to diagnose diseases in the early stages, prevent the development of severe forms, and determine the effectiveness of drugs in the treatment of external respiration disorders.
Correctly performed spirometry, taking into account all the individual characteristics of the patient, provides comprehensive information about the state of the respiratory system. Painlessness, simplicity of the procedure, immediate results, absence of side effects are the undeniable advantages of this type of diagnosis.
Interesting
Spirometry is designed to assess the condition of a person's lungs. The procedure has a number of clinical purposes, including evaluative, educational, and diagnostic. This study is prescribed to identify lung pathologies of various origins, monitor the patient’s condition and evaluate the therapeutic effectiveness of treatment. In addition, spirometry is performed to teach a person proper breathing techniques. The scope of this type of research is quite wide. In this article we will look at the procedure for spirometry, indications, contraindications and features of its use.
What is the FEV1 norm, we will consider in this article.
A human being consists of three main elements:
Failure of at least one of these elements inhibits the functioning of the lungs. Spirometry allows you to assess respiratory parameters, diagnose existing respiratory tract pathologies, characterize the severity of the disease and understand whether the prescribed therapy is effective.
Many people are interested in the norm.
Indications for spirometry are:
All of the above cases are a reason to prescribe spirometry. This type of research is not widespread; many people simply have no idea about it. However, it is very popular in medical fields such as allergology, pulmonology and cardiology. Together with spirometry, the patient can be referred to dynamometry, which determines the strength of the pulmonary muscles. Peak expiratory flow is also determined here.
Spirometry, otherwise called a function test or FVD, plays a major role in the diagnosis of chronic obstructive pulmonary disease and asthma. Experts advise undergoing a ventilation test regularly if the patient has one of the above-mentioned pathologies. This will help prevent the occurrence of associated complications.
A table of normal spirometry readings is presented below.
The study of respiratory function is carried out using a spirometer. This is a special device that is capable of reading lung parameters during a functional examination. With its help it is also possible to stimulate the respiratory function. This is especially true for patients who have undergone surgery on the lungs and have certain problems with the functioning of the respiratory system.
Spirometers come in different types, including:
The methods for carrying out the procedure also differ. Breathing can be examined at rest, or forced expiration is assessed, as well as ventilation of the lungs to the maximum possible. The normal lung volume is indicated as average. There is also such a thing as dynamic spirometry, which shows the functioning of the lungs at rest and immediately after physical activity. Spirometry with a drug response test is sometimes used:
Modern spirometric devices allow additional diffusion studies. This applies to clinical diagnostic methods. The study involves assessing the qualitative characteristics of oxygen entering the blood and carbon dioxide released during inhalation and exhalation. If diffusion is reduced, this is a sign of serious pathologies in the function of the respiratory organs.
In the field of spirometry, there is another important test called bronchospirometry. This examination is carried out using a bronchoscope and allows you to evaluate the lungs and external respiration separately. During bronchospirometry, anesthesia must be administered. The examination helps calculate lung vitals, respiratory rate, etc.
To obtain the most accurate test results, it is important to properly prepare for spirometry, especially when performing the procedure on an outpatient basis. The study of forced expiratory volume is carried out on an empty stomach in the morning, or at another time, but with the condition of skipping a meal. If this is not possible, it is recommended to eat a small amount of something low-fat a few hours before the procedure.
Spirometry is performed on an outpatient basis. Different methods and types of research require different sequences of actions. The patient's age and general health may also influence the steps taken during the examination. If we are talking about performing spirometry on a child, then creating comfortable conditions is considered a prerequisite so that the child does not experience fear and anxiety. Otherwise, the indicators may be blurred.
Standard conditions for spirometry:
If the patient does not have information about his height and weight, the doctor takes the necessary measurements. Before starting the procedure, a special disposable mouthpiece is placed on the device.
Patient information is entered into the spirometer program.
The doctor gives explanations about how to breathe during the examination, how to inhale as much as possible. The patient's position should be with a straight back and slightly elevated head. Sometimes spirometry is performed in a supine or standing position, which is necessarily recorded in the program. The nose is pinched with a special clothespin. The patient's mouth must fit tightly around the mouthpiece, otherwise the readings may be underestimated.
The study begins with a phase of calm and even breathing. At the doctor's request, take a deep breath and exhale with maximum effort. Next, the air speed is checked during a quiet exhalation. To get a complete picture, the breathing cycle is carried out several times.
The duration of the procedure is no more than 15 minutes.
Spirometry provides data on many indicators that have certain standards. Interpretation of the study results makes it possible to identify pathologies in the respiratory system and prescribe the correct therapy. The main indicators of spirometry include:
There are certain features of spirometry in children. The first is age, the child should not be younger than five years old. This limitation is explained by the fact that at a younger age the child is not able to exhale correctly, which will reduce the performance. From the age of nine, a child can undergo the study as an adult. Before this age is reached, it is important to create a comfortable atmosphere for the baby using toys and friendly treatment. For this reason, spirometry in young children should be performed in specialized centers specializing in pediatrics.
Before the procedure, it is important to explain to the child how to inhale and exhale. Sometimes pictures and photos are used for explanations. The specialist should carefully ensure that the child’s lips fit tightly around the mouthpiece.
The indicators obtained during spirometry are compared with the norm, taking into account gender, weight and age. The survey conclusion is a graph with interpretation of the indicators. The attending physician will be able to provide an explanation of the results obtained.
The following data is decrypted:
Spirometry in adult patients can be performed by a number of specialists, including a pulmonologist, nurse, or functional diagnostician. In childhood, the procedure is performed by a pediatrician. There are also compact spirometers that allow you to do a simple test at home. This is relevant for people suffering from asthma who need to control possible attacks.
Spirometry is a safe procedure and allows its use without restrictions. Side effects include slight dizziness during the procedure, but this phenomenon goes away after a couple of minutes.
However, forced inhalation and exhalation can affect intracranial and intra-abdominal pressure, so the procedure is not recommended after abdominal surgery, myocardial infarction, stroke, bleeding of the lungs, pneumothorax, hypertension and poor blood clotting. Age over 75 years is also a contraindication.
We examined the FEV1 norm and other indicators.
