The tiffno index is an indicator. Basic terms and indicators of spirometry

The amount of air that the lungs can hold, i.e. contained in the lungs at the end of maximum inspiration is called total capacity lungs (LEL). It consists of the residual air volume (RVA) remaining in the lungs after maximum exhalation, and lung capacity.

Spirometry index: lung capacity (VC)

VC, in turn, make up the tidal volume (TO), i.e. the volume of air inhaled and exhaled with each respiratory cycle, inspiratory reserve volume (IRV) - the volume that can be inhaled after a normal inspiration to the level of maximum inspiration, expiratory reserve volume (ERV) - the volume of air that can be exhaled from a quiet maximum exhalation. Inspiratory VC is calculated as the difference in lung volume between a full exhalation and a full breath. RO VID and RH add up to the functional residual capacity (FRC). VC is not an indicator of the functional ability of the device external respiration. At the same time, a violation of physiological processes can cause changes in lung volumes, so it is necessary to know their normal values ​​and be able to assess deviations from the norm. The value of VC depends mainly on gender, age and height (on body weight only insofar as it correlates with height).

Of greatest interest is not the absolute value of VC, but its relation to the standards developed taking into account the listed factors. To calculate the proper VC (JEL), nomograms, tables were compiled and formulas were derived. Preference should be given to the following formulas: JEL (l) for men 25-60 years old is 0.052 x P - 0.028 x B - 3.20, and for women of the same ages 0.049 x P - 0.019 x B - 3.76, where P is height (cm); B - age (years). It is believed that the actual VC corresponds to the proper one if it differs from it by no more than ± 15%, and the main practical significance is the decrease in the actual VC (VC more than 90% VC is the norm, 90-85% VC is the conditional norm, or the border zone ). Most often, a decrease in VC is the result of an absolute decrease in the amount of functioning lung tissue (pulmonary edema, pneumonia, fibrosis, atelectasis, blockage of the main bronchus, etc.), less often - mobility restrictions chest, aperture.

An increase in VC is usually observed in trained individuals (athletes, representatives of professions in which work requires significant physical stress) and is not a pathological sign.

Forced vital capacity (F expiratory VC) is calculated as the difference in volume between the start and end points of forced expiration after the deepest possible inspiration.

Spirometry index FEV 1

FEV 1 - forced expiratory volume in the first second of the FVC maneuver, is the main criterion for diagnosing the presence of obstructive disorders; a decrease in FEV1 by 20% or more from the due value indicates the presence of severe obstruction.

Spirometry index: Tiffno index

FEV 1 /VC (Tiffno index) is expressed as a percentage and is a sensitive index of the presence or absence of bronchial obstruction. The due value is considered to be 80% for men and 82% for women, the lower limit of the norm is 70%; conditional norm - 70-65%.

Spirometry index SOS 25-75 :

SOS25-75 - the average volumetric expiratory flow rate, determined during expiration from 25 to 75% of the FVC of the exhalation, or the maximum average expiratory flow. The decrease in airflow velocity is directly proportional to the degree of narrowing of the bronchial lumen. Violations of the patency of the bronchus are possible when it is deformed by a tumor, silicotic conglomerates, accumulation of sputum that is difficult to separate, edema of the bronchial wall, bronchospasm, and due to other causes in various combinations.

Spirometry index POS

POS - peak volumetric flow, the maximum flow achieved during the exhalation of the first 20% of FVC. If POS is determined later, then this indicates that the maneuver was performed incorrectly, with a late development of maximum effort.

Spirometry index MOS

MOS - instantaneous volumetric velocities, calculated at a certain volume of exhalation. MOS25 is calculated at the time of exhalation 25% FVC, MOS50 at the time of exhalation 50% FVC, and MOS75 at the time of exhalation 75% FVC. A decrease in MOS, especially MOS50 and MOS75, indicates the presence of early expiratory disturbances and is valuable diagnostic criterion, since it is detected earlier than the decrease in FEV1.

Tpos is the time required to reach the POS. In healthy people with correct execution maneuver Tpos does not exceed 0.1 s, with an increase in Tpos, one can speak of an insufficient effort applied by the patient to perform forced exhalation.

Tfzhel - the time required to exhale 100 FVC of expiration, if the TFVC is less than 1 s, then this most likely indicates an incomplete exhalation. An increase in TFVC is often found with obstruction.

Currently, for the study of respiratory function, automatic spirometers are most often used.

The study should be carried out in conditions of relative rest: in the morning or afternoon, on an empty stomach or 2 hours after a light breakfast, after resting for 15 minutes, in a sitting position. To obtain undistorted values, it is necessary to cancel bronchodilator therapy 12 hours before the study, quit smoking at least 2 hours before the study. Failure to comply with these conditions may affect the results obtained, which must be taken into account when interpreting them. When performing spirometry, the subject is in a sitting position, holds the mouthpiece of the spirometer in one hand, a clamp is applied to the nose. After connecting to the device, a person performs 2-3 calm breaths and exhalations to adapt to breathing into the device. Then, on command, a deep full exhalation is made from the level of calm breathing, and then a deep calm breath, after which, without holding the breath, a full exhalation is performed with maximum effort, which must be achieved at the beginning of the maneuver and maintained throughout its duration. The study is repeated at least three times. The criterion for the correctness of the maneuvers is the difference in the results between attempts, not exceeding 5%.

In order to more reliably judge capacitive and high-speed respiratory function indicators, the data obtained must be adjusted to the conditions that were in the lungs: at body temperature, ambient pressure and full saturation with water vapor, or BTPS. For this purpose, two corrections are made, taking into account the change in volume with decreasing temperature and in connection with the condensation of water vapor during cooling. To simplify calculations, the correction factor can be calculated in advance (Table 12).

Table 12. Coefficients for converting gas volume to the BTPS system: BTPS - body temperature, pressure, saturated

Most modern spirometers allow you to determine the minute volume of respiration (MOD) - the volume of air that is ventilated in the lungs in 1 minute to provide the body with the necessary amount of oxygen and remove carbon dioxide. If breathing is uniform, then the MOD is the product of the depth of breathing and its frequency; if it is uneven, then the MOD is equal to the sum of all respiratory volumes per minute. The value of MOD depends on the body's need for oxygen and the degree of utilization of ventilated air, i.e. on the amount of oxygen absorbed from a given volume of air. The need for oxygen, even in the same person, varies dramatically depending on many factors, primarily physical activity. The degree of absorption of oxygen from ventilated air also depends on many factors. Thus, the MOD increases with the deterioration of the function of cardio-vascular system, violation of the normal relationship between blood flow and ventilation of the lungs, etc. Highly importance has the state of the alveolar membrane. With pneumosclerosis of toxic origin or pneumoconiosis, when the diffusion process is significantly difficult, an increase in ventilation occurs even with an unchanged oxygen demand.

The study is carried out in conditions of basal metabolism: in the morning, on an empty stomach, after an hour's rest in a prone position, in a quiet, dimly lit room with a comfortable air temperature. Deviations from these stringent conditions introduce significant changes in the results obtained. MOD is determined either by recording and subsequent processing of spirograms, or by measuring the volume of air exhaled over a known time using a gas meter or high-capacity spirometer. The latter method is somewhat less accurate, but quite accessible and widely used. Depending on the design of the device, a mask with a rubber gasket, tightly pressed to the face, or a mouthpiece is used; in the latter case, a clamp is applied to the nose. The advantage of using a mouthpiece is a significant reduction in "dead space". The subject in a sitting position breathes calmly for several minutes, until the amount of air exhaled per minute becomes the same. Even in healthy people, normal MOD values ​​vary widely (from 3 to 10 liters) depending on gender, age, height, and body weight. Most often, in healthy men, the MOD is 5-7 liters, in women - somewhat less. For a more accurate answer to the question of whether the actual MOD corresponds to the proper one in a particular case, the obtained value, reduced to BTPS, is compared with the value of oxygen consumption, and if this is not possible, with the proper oxygen consumption. Divide by 40 to establish the proper minute oxygen consumption (DMOD) (the value of the proper basal metabolic rate divided by 7.07).

Spirometry index: h frequency and depth of breathing.

The depth of respiration can be measured using a spirograph or, although less accurately, a spirometer, and also by dividing the MOD by the respiration rate. Fluctuations in the depth of breathing, even at rest, are significant (from 300 to 900 ml). In sick and untrained healthy people, an increase in ventilation often occurs with an increase in breathing and a decrease in its depth. Frequent and shallow breathing is ineffective, since the alveoli in this case are poorly ventilated, the influence of "dead space" increases. Healthy and trained people breathe less frequently and more deeply. Normally, the respiratory rate can range from 10 to 30 cycles per minute, but for most it is 16-18 and rarely exceeds 20.

Spirometry index: m maximal lung ventilation (MVL)

is the maximum amount of air that can be ventilated in 1 minute. MVL is a very important dynamic indicator that gives an idea of ​​the amount of unused breathing reserves, the resistance that occurs in the airways, etc. MVL may decrease in restrictive processes, mainly due to a decrease in VC. A sharp decrease in MVL, not combined with the same sharp decrease in VC, as a rule, indicates an increase in breathing resistance and indicates bronchial obstruction. Determination of a reliable value of MVL is associated with some methodological difficulties. The test's fitness, his ability to choose the optimal combination of frequency and depth of breathing, and the need for a certain volitional effort have a significant impact on the result. Research is carried out as follows. The patient is asked to breathe for 15 seconds at a maximum frequency (40-60 times per minute) and depth. The result obtained is multiplied by 4, i.e. determine the volume of ventilation for 1 min. If the study causes difficulties due to the patient's condition, it can be carried out for 10 s and the result multiplied by 6. This is followed by reduction to BTPS conditions. DMVL is for men 25-60 years old JEL x 25 l min "1, and for women of the same age JEL x 26 l min" 1, and values ​​​​of more than 85% are taken as the norm, and 85-75% are taken as the conditional norm.

To assess the state of bronchial patency, it is possible to use pneumotachometry (PTM)

This is the definition of maximum (peak) airflow rates. The indicators obtained during forced inhalation and exhalation are not quite accurately called the power of inhalation and exhalation (MVD and Mvyd). The study is performed using a pneumotachometer, from the tube of which, after maximum exhalation, a maximum breath is produced (Min) or after a maximum breath into the tube, a maximum exhalation is produced (Min). Samples are repeated 4-5 times at short intervals. The greatest value has Mvyd. Normally, its fluctuations were noted over a wide range (3.5-7.3 l s-1 in men and 3-5.9 l s-1 in women), which significantly complicates the interpretation of the results. There are no generally accepted Mvyd standards. An approximate idea of ​​the proper value for a given subject can be obtained by multiplying the actual VC by 1.2. However, the use of this technique does not always give reliable results. At the same time, the determination of Mvyd is very valuable when comparing the results of examination of the same patient in the course of dynamic observation, in the selection of optimal bronchodilators, as a screening during professional examinations, etc.

To increase the diagnostic value of the study of respiratory function, various tests are often used, which make it possible to clarify the mechanism for the development of the identified changes. The bronchodilator test is used to determine the reversibility of obstruction and may be a valuable criterion in differential diagnosis bronchial asthma and obstructive bronchitis. Provocative tests reveal latent bronchospasm (test with methacholine), as well as the etiology of bronchospasm (test with exercise, cold air, industrial allergens).

Research is indispensable for finding out:

• The absence or presence of diseases of the respiratory system, when the patient has complaints of coughing, shortness of breath, sputum production.
• What stage of the established disease the patient currently has and whether the treatment is effective.
• The degree of influence on the bronchi and lungs of the patient factors environment and bad habits.
• Influence of physical activity on the bronchopulmonary system in athletes before the start of training or competition.

Spirometry can be prescribed from the age of six. Spend in the morning, a few hours after breakfast. Immediately before the procedure, the patient should rest for at least 15 minutes in a sitting position. The staff who will monitor the procedure must instruct the patient, where he talks in detail about the stages of spirography and the actions of the patient himself.

If the patient takes theophylline preparations, they must be canceled a day before the study, and if inhaled preparations, then 12 hours before.

The procedure will not take much time and will not bring pain or discomfort to the patient. A clamp is put on the nose of a person to prevent air leakage, with the help of a mouthpiece, the subject is connected to the spirograph. Within 5 minutes, the patient breathes calmly and measuredly. Then he exhales as deeply as possible, and after him - the same depth of inhalation and again - exhale, and again - inhale. To obtain reliable results, the above cycles are carried out 3 times.

The main indicators of spirometry and their meaning

To determine the degree of impaired respiratory function, many indicators are needed, but the most important are:

1. FVC - forced vital capacity of the lungs.
2. FEV1 - forced expiratory volume in the first second.
3. Gensler's index or FEV1/FVC.
4. VC - vital capacity of the lungs.
5. DO - tidal volume.
6. Tiffno index or FEV1/VC.

Spirometry indicators depend on the age, health status and constitution of the patient. The following are considered normal digital values indicators: DO - 500-800 ml, FEV1 - 75%, Tiffno index - 70% and above. The remaining indicators are calculated using special formulas and do not have specific digital values.

Spirometry is needed to determine the type of respiratory system disorders in a particular patient. Pathophysiologists distinguish 2 types of respiratory dysfunction:

1. An obstruction is a blockage respiratory tract due to edema of the mucous membrane, spasm of the smooth muscles of the bronchi, a large number sputum. In this case, FEV1/FVC will be less than 70% and FVC will be above 80%.
2. Restriction - a decrease in the extensibility of the lung tissue itself or a decrease in its volume. Spirometry results will be as follows: FVC below 80%, FEV1/FVC ratio above 70%.

Useful video

Standards for the formation of conclusions on spirography.

FAQ:

Where can spirometry be done?

Answer: Apparatus for spirometry - spirometers - are in every clinic in the functional diagnostics rooms or directly in the therapist's office. A pulmonologist, therapist or functional diagnostician can conduct research.

Does the norm of spirometry differ in children and adults?

Answer: yes normal performance spirometry is strikingly different in children and adults and depends on the sex, constitution, age and physical development of the patient.
Unfortunately, many patients do not fully understand the significance of this examination and consider visiting the functional diagnostics room a waste of time. And then, when the prescribed drugs do not have the desired effect, they accuse the doctor of incompetence and negligence, forgetting that without complete examination it is almost impossible to prescribe adequate treatment.

With spirometry in quiet breathing mode, DO, respiratory rate (RR) are recorded and the minute respiratory volume (MOD) of rest is calculated.

Minute respiratory volume (MOD) - general ventilation during quiet breathing per minute (6-8 liters).

These data characterize the intensity of the ventilation process at the time of the study and do not characterize the state of the ventilation apparatus. Their changes are the same in healthy and patients with lung pathology.

The study of the state of the ventilation apparatus (ventilation capacity of the lungs) is carried out using tests that reveal the maximum volume and speed parameters of the ventilation apparatus.

Maximum lung ventilation (MVL) is the maximum volume of air that a patient can ventilate in 1 minute.

The MVL value is determined with the deepest and most frequent breathing for 12 seconds. Then recalculate the resulting volume for 1 minute. This indicator reflects the severity of airway obstruction, the state of the respiratory muscles, and is used in the study of athletes.

Forced expiratory volume in 1 second (FEV 1)- the volume of air in the first second with the most rapid and deep exhalation (when determining FVC).

Restrictive variant respiratory failure: normal FEV 1 with a decrease in the value of VC. Tiffno index 70% or more than normal.

mixed type respiratory failure (restriction combined with obstruction): a decrease in FEV 1, a decrease in the Tiffno index, a decrease in VC.

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 an adult healthy person, the number of respiratory movements is 16-20 per 1 minute. The respiratory rate depends on gender, age, profession, body position during the study. Physiological increase in breathing is observed during physical exertion, emotional arousal, 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 a liquid or gas, pneumosclerosis, fibrosis, thromboembolism pulmonary artery, pulmonary edema;

b) with insufficient depth of breathing: difficulty in contracting the intercostal muscles or diaphragm when sharp pains(dry pleurisy, acute myositis, intercostal neuralgia, fracture of the ribs, development of tumor metastases in the ribs); a sharp increase in intra-abdominal pressure and high standing of the diaphragm (ascites, flatulence, late dates pregnancy, hysteria).

Pathological decrease in breathing observed when the respiratory center is depressed and its excitability decreases (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, emphysema).

Definition of TO(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 scale (20 or 40 ml, depending on the type of spirograph). Normally, DO is 300-900 ml (average 500 ml).

A decrease in DO, as a rule, is combined with an increase in RR, and an increase in DO, as a rule, with a decrease in RR (see above for reasons). However, sometimes there can be a simultaneous decrease in DO and RR (rare 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 breathing (MOD)

The amount of ventilated air for 1 min. MOD is determined by multiplying DO by the respiratory rate: MOD (l) \u003d DO (ml) x BH. If the respiratory waves are not the same, then the MOD is determined by summing up to one minute. Normally, the MOD ranges from 4-10 liters (on average 5 liters). MOD is a measure of pulmonary ventilation, but not an absolute indicator of the effectiveness of alveolar ventilation; depends on DO, BH and dead space. With the same MOD, 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 getting into the alveoli, effective alveolar ventilation decreases. With the same MOD values, but with slow and deep breathing, effective alveolar ventilation is much higher. Thus, the determination of the MOD, the frequency and depth of breathing and the comparison of these indicators with each other and in dynamics acquires practical importance.

Determining the proper MOU (DMOD)6 carried out according to the formula A.G. Dembo. The calculation is based on the proper basal exchange, which is found according to the table of Harris and Benedict. First, DPO 2 is calculated by the formula: DPO 2 \u003d DOO: 7.07 (the coefficient 7.07 is the product of the thermal equivalent of 1 l 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 each liter of ventilated air. MOD depends on the deterioration of the use of ventilated air, difficulty in normal ventilation, disruption of gas diffusion processes, the body's need for O 2, and the intensity of metabolic processes.

MAUD increases:

a) with an increase in the body's need for oxygen (I and II degree of pulmonary and heart failure);

b) with an increase in metabolic processes (thyrotoxicosis);

c) with some lesions of the central nervous system.

MOD decreases:

a) with severe III degree of pulmonary or heart failure due to the depletion of the body's compensatory capabilities;

b) with a decrease in metabolic processes (myxedema);

c) with depression of the respiratory center.

Determination of inspiratory reserve volume (IRVd.) - The maximum volume of air that a person can inhale after a normal breath. The height of the maximum inspiratory wave (in mm) is measured from the level of calm breathing and multiplied by the scale of the spirograph scale. Normal ROVD. equal to 1500-2000 ml. Rovd.= 45-55% WISH. Of great practical importance is the value of ROVD. does not, since in healthy individuals it is subject to significant fluctuations. ROVD. decreases with a decrease in the respiratory surface of the lungs and in the presence of reasons that prevent the maximum expansion of the lungs.

Determination of expiratory reserve volume (ROvyd.) - the maximum volume of air that can be exhaled after a normal exhalation. The value of the maximum exhalation wave (in mm) is measured from the level of a calm exhalation and multiplied by the scale of the spirograph scale. In the norm ROvyd. equal to 1500-2000 ml. ROvyd. is approximately 25-35% VC. Due to the significant variability, this indicator is of little practical importance. Significant reduction in ROvyd. observed in obstructive processes (emphysema, bronchial asthma, chronic obstructive bronchitis). With stenotic breathing, the proportion of ROvyd. in VC increases.

Determination of vital capacity of the lungs (VC) - the maximum amount of air that can be exhaled after a maximum inhalation. VEL is the sum of TO, ROVD. and ROvyd. ZEL \u003d TO + Rovd. + ROvyd.

When determining VC by spirogram, the distance from the top of the inspiratory knee (maximum inspiration) to the top of the expiratory knee (maximum expiration) is measured in millimeters and multiplied by the scale of the spirograph scale. Normal VC ranges from 3000 to 5000 ml. Its value depends on age (up to 35 years, it increases, then gradually decreases), gender (in women, VC values ​​are lower than in men), height, body weight, and body position. For a correct assessment of the results, it is necessary to determine the ratio of the actual VC to the due (JEL). To determine JEL, use the formulas:

JEL in l \u003d 0.052xP-0.028xV-3.20 (for men);

JEL in l \u003d 0.049xP-0.019xV-3.76 (for women);

where P is height, B is age.

Deviation of VCL from JEL should not exceed 15%. Therefore, a decrease in VC below 85% of the due value is of practical importance.

VC decreases:

a) at pathological conditions preventing the maximum expansion of the lungs (exudative pleurisy, pneumothorax);

b) with a decrease in the area of ​​the functioning lung parenchyma, which is associated with changes in the lung tissue itself (pulmonary tuberculosis, pneumonia, pneumofibrosis, lung abscess, atelectasis, etc.);

c) with depletion of the elastic framework of the lungs (emphysema);

d) with extrapulmonary pathology: processes that limit the expansion of the chest (kyphoscoliosis, ankylosing spondylitis), limitation of diaphragm mobility, increased intra-abdominal pressure (ascites, flatulence, etc.);

e) in diseases of the cardiovascular system in the presence of congestion in the pulmonary circulation;

e) with a sharp general weakness;

g) in violation of the functional state of the nervous system.

The diagnostic value of VC in a single study cannot be considered sufficient, however, in a comprehensive study of respiratory function, this indicator is very important both for calculations and comparison with other values, and for assessing the degree, type of respiratory failure (RF).

Definition of forced VC (FVC) - the volume of air that can be exhaled after a maximum inhalation at the maximum possible rate. 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 rectilinear course and corresponds to the maximum and constant exhalation rate. Then the expiratory rate slows down, the curve becomes less steep and becomes curvilinear. The rectilinear course of the FVC curve is due to exhalation due to the elasticity of the lung tissue. Curvilinear VC corresponds to the increasing effort of the expiratory muscles.

The determination of FVC is carried out by measuring the height of the curve from its upper to its deepest part (in mm) and then multiplying by the scale of the spirograph scale. Normally, FVC is 8-11% (by 100-300 ml) less than VC, mainly due to an increase in resistance to air flow in the small bronchi. In violation of bronchial patency and increased resistance to air flow, the difference increases to 1500 ml or more. This is observed in bronchial asthma, chronic obstructive bronchitis, emphysema.

Determination of forced expiratory volume in 1 sec (FEV 1) - the volume of air that the subject can exhale in the first second of maximum forced exhalation. To determine this indicator on the FVC spirogram, from the zero mark corresponding to the beginning of expiration, a segment equal to 1 second is set aside (1 cm at a tape pull speed of 600 mm / min or 2 cm at a tape drive speed of 1200 mm / min). perpendicular to the point of intersection with the FVC curve, measure the height of the perpendicular in mm and multiply by the scale of the spirograph scale,

Normal FEV 1 ranges from 1.4 to 4.2 l / s. For a more correct assessment of the results, the ratio of the actual FEV 1 to the due FEV 1 (DOFE 1) is determined. To calculate DOFE 1, the following formulas are used:

DOFE 1 \u003d 0.36xP-0.031x6-1.41 (for men);

DOFE 1 \u003d 0.026xP-0.028xV-0.36 (for women).

Of practical importance is the decrease in FEV 1 below 75% DOFE 1. The diagnostic significance of FEV 1 approximately corresponds to the significance of VC, however, FEV 1 decreases to a greater extent in obstructive processes.

Definition of the Wotchal-Tiffno test. This indicator represents the relative one-second capacity, the percentage of FEV 1 to VC.

Tiffno test \u003d 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 has great importance in the detection of obstructive processes in the lungs and is sharply reduced in bronchial asthma, emphysema.

To identify the role of bronchospasm in the occurrence of respiratory failure and reduce these indicators, pharmacological tests with bronchodilators (aminofillin, adrenaline, ephedrine, etc.) are used. FVC is recorded before and after the administration of bronchodilators. In the presence of bronchospasm after the introduction of bronchodilators, the one-second capacity increases.

Determination of maximum lung ventilation (MVL):(respiration limit, maximum respiratory capacity, maximum minute volume).

MVL is the maximum amount of air that can be ventilated in one minute. It characterizes the functional ability of the external respiration apparatus.

Definition of MVL:

a) calculate the respiratory rate at maximum ventilation of the lungs (for 15 seconds), multiply this value by 4 and thus determine the respiratory rate during MVL for 1 min;

b) DO is determined at maximum lung ventilation. To do this, measure the value of the respiratory cycle in millimeters and multiply by the scale of the spirograph scale;

c) multiply BH by DO (with MVL)

MVL in l \u003d BH with MVL x DO with MVL.

Normally, MVL is in the range of 50-180 liters per minute. Its value depends on gender, age, height of the subject, body position. For a correct assessment of the results obtained, it is necessary to bring the actual MVL to the proper one. To calculate, use the formulas:

DMVL=JELx25 (for men);

DMVL = JELx26 (for women).

Of practical importance is the reduction of MVL below 75% of the due value. MVL depends on muscle strength, lung and chest compliance, and airflow resistance. Its decrease is observed in processes accompanied by a decrease in lung compliance and a violation of bronchial conduction. MVL decreases in various lung diseases and heart failure. Its decrease increases with the progression of pulmonary or heart failure. MVL is an indicator that subtly reacts to the state of the nervous system.

Determination of the reserve of breathing (RD)

The respiratory reserve indicates how much the patient can increase ventilation.

RD in l = MVL-MOD

RD in% DMVL = RD / MVL x 100%

RD in % DMVL is one of the valuable indicators of the functional state of the external respiration apparatus. Normally, RD = 70-80 liters and exceeds the MOD by at least 15-20 times. RD=85-95% MVL.

RD decreases with respiratory and heart failure to 60-55% and below.

Similar information.

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 prescribed for the detection of pathologies of the lungs various genesis, monitoring the patient's condition and assessing the therapeutic effectiveness of treatment. In addition, spirometry is performed to teach a person the correct breathing technique. The scope of this type of research is quite wide. In this article, we will consider the procedure for spirometry, indications, contraindications and features of its use.

What is the FEV1 norm, we will consider in this article.

Indications

A person is made up of three main elements:

1. The airways that allow air to pass into the lungs.
2. Lung tissue that promotes gas exchange.
3. The chest, which is essentially a compressor.

Failure of at least one of these elements depresses the functioning of the lungs. Spirometry allows assessing respiratory parameters, diagnosing existing pathologies of the respiratory tract, characterizing the severity of the disease and understanding whether the prescribed therapy is effective.

The norm is of interest to many.

Indications for the appointment of spirometry are:

1. Respiratory diseases of a regular nature.
2. Cough in chronic form, shortness of breath.
3. In addition to other examinations of the respiratory tract in the diagnosis of pulmonary pathologies.
4. Search for the causes of failure in gas exchange processes in the body.
5. Assessment of the risks of prescribed therapy for and bronchi.
6. Identification of signs of airway obstruction (in the case of smoking patients) in the absence of severe symptoms of this pathology.
7. general characteristics physical condition person. What is the volume of maximum ventilation of the lungs, consider below.
8. In preparation for surgery and lung examinations.
9. Diagnostics early stages control of development and evaluation of further forecast.
10. Determination of the degree of damage to the respiratory function in tuberculosis, bronchial asthma, bronchiectasis, etc.
11. Restriction diagnostics.
12. Allergic reactions (especially those of an asthmatic nature).

All of the above cases are the reason for the appointment of spirometry. This type research is not ubiquitous, many simply do not have an idea about it. However, it is very popular in such medical fields as allergology, pulmonology and cardiology. Together with spirometry, the patient can be directed to dynamometry, which determines the strength of the pulmonary muscles. This is where the peak expiratory flow rate is determined.

Spirometry, otherwise known as a function test or FVD, plays a major role in the diagnosis of chronic obstructive pulmonary disease and asthma. Experts advise to undergo a lung ventilation test regularly if the patient has one of the aforementioned pathologies. This will help prevent the occurrence of associated complications.

A table of normal spirometry values ​​is presented below.

general information

The study of respiratory function is carried out using a spirometer. This is a special device that is able to read lung parameters during a functional examination. It can also stimulate 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.

Types of spirometry

There are spirometers different types, including:

1. Computer. Equipped with ultrasonic sensors. Referred to as the most hygienic spirometer. It has a high accuracy of indicators, since it contains a minimum of internal details.
2. Plethysmograph. This is a special chamber where the examined patient is located, and special sensors transmit indicators. This type of spirometer is considered the most accurate at the moment.
3. Water. It does not apply to ultra-precise spirometers, but the measurement range is quite wide.
4. Dry mechanical. The device is quite small, while it can read information in any position of the patient. The range of action is quite small.
5. Stimulating or motivating.

The methods of the procedure also differ. Breathing can be examined at rest, or forced exhalation is assessed, as well as ventilation of the lungs to the maximum possible. The norm of 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 reaction test is sometimes used:

1. Test with medicines- bronchodilators, such as "Ventolin", "Salbutamol", "Berodual", etc. Such medicines have an expanding effect on the bronchi and help to reveal spasm in a latent form. Thus, the accuracy of the diagnosis is increased and the effectiveness of the therapy is evaluated. It is important to understand that obstructive pulmonary disease leads to changes in the flow-volume loop.
2. Expert provocative test. It is carried out to clarify the diagnosis of asthma. Such a test can reveal hyperreactivity and emerging spasm in the bronchi. The test is performed using methacholine, which is inhaled by the patient during spirometry. In the spirometry table, normal values ​​​​are indicated in great detail.

Additional study of diffusion function of the lungs

Modern spirometry devices allow for an additional study of diffusion. This applies to methods clinical diagnostics. 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 study called bronchospirometry. This examination is carried out using a bronchoscope and allows you to evaluate the lungs and external respiration separately. For bronchospirometry, anesthesia should be administered. The examination helps to calculate the vital lung, respiratory rate, etc.

Preparation and holding

To obtain the most accurate results of the study, 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 meals. If this is not possible, it is recommended to eat something low-fat in a small amount a few hours before the procedure.

1. Stop smoking before the procedure.
2. You can not drink tonic drinks on the eve of the examination.
3. Drinking alcohol before spirometry is also prohibited.
4. Sometimes you may need to stop taking certain medications.
5. Clothing during the procedure should not hinder movement and interfere with breathing.
6. Before the procedure, the doctor must measure the height and weight of the patient, as these indicators are important for evaluating the results of the study.
7. Before starting the procedure, you need to be at rest for about 15 minutes, so you should come in advance. Breathing should be calm.

Spirometry is performed on an outpatient basis. Miscellaneous Methods and types of research involve different sequences of actions. The algorithm of steps during the examination can also be influenced by the age of the patient and general state health. If we are talking about conducting spirometry in a child, then the creation of comfortable conditions is considered a prerequisite so that the child does not experience fear and excitement. Otherwise, the indicators may be blurred.

Standard Conditions

Standard conditions for spirometry:

If the patient does not have information about his height and weight, then the doctor takes the necessary measurements. Before starting the procedure, a special disposable mouthpiece is put on the device.

Information about the patient is entered into the spirometer program.

The doctor gives explanations on how to breathe during the study, how to inhale as much as possible. The position of the patient should be with a flat back and a slightly raised head. Sometimes spirometry is performed in a supine or standing position, which is mandatory recorded in the program. The nose is clamped with a special clothespin. The patient's mouth must fit snugly around the mouthpiece, otherwise the readings may be underestimated.

The study begins with a phase of calm and even breathing. At the request of the doctor, a deep breath is taken and exhaled with maximum effort. Next, the air velocity is checked during a calm 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.

Indicators and norm of FEV1

Spirometry provides data on many indicators that have certain norms. Interpretation of the results of the study makes it possible to identify pathologies in respiratory system and prescribe the correct therapy. The main indicators of spirometry include:

• VC. This is nothing more than the vital capacity of the lungs, which is calculated by the difference between the volume of inhaled and exhaled air. This is the actual figure. There are other indicators besides FEV1.
• FZhEL. actual lung capacity. It is also determined by the difference between the volume of inhaled and exhaled air, however, exhalation in this case must be forced. The norm is 70-80% VC.
• ROVD. This is the inspiratory reserve volume. Determines the volume of air that the patient can inhale after a standard breath. Norm 1.2-1.5 liters
• ROvyd. Expiratory reserve volume. This is the volume of air inhaled after a standard exhalation. The norm is 1.0-1.5 liters.
• TL or total lung capacity. Normally it is 5-7 liters.

• Norm FEV 1. The volume of exhaled air at maximum forcing in the first second. The norm is more than 70% FVC.
• Tiffno index. Designed to determine the quality of the patency of the respiratory system. The norm is 75%.
• POS. Exhaled air volume. The norm is more than 80% FEV1.
• MOS. Instantaneous volumetric velocity. This is the rate at which air is exhaled. More than 75% is considered normal.
• RR or respiratory rate. The norm is 10-20 breathing maneuvers per minute.

There are certain features of spirometry in children. The first is age, the child must 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 performance. From the age of nine, a child can be examined as an adult. Before this age is reached, it is important to create a comfortable atmosphere for the baby with the use of toys and friendly treatment. For this reason, spirometry in young children should be performed in special centers specialized 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 clarification. The specialist must carefully monitor that the child's lips fit snugly around the mouthpiece.

Deciphering the results

The indicators obtained during the spirometry are compared with the norm, taking into account gender, weight and age. The survey conclusion is a graph with the interpretation of indicators. An explanation of the results obtained can be given by the attending physician.

The following data is decrypted:

1. Inhaled volume of air in milliliters.
2. Exhaled volume after the deepest breath.
3. Exhaled gas volume.
4. The difference between inhaled and exhaled volume of air.
5. Exhalation and inhalation speed.
6. Volume of forced exhaled air.

Features of the procedure

Spirometry in adult patients can be performed by a number of specialists, including a pulmonologist, nurse or functional diagnostic. AT childhood the procedure is performed by a pediatrician. There are also compact spirometers that allow you to do the simplest test at home. This is relevant for people suffering from asthma who need to control possible attacks.

Spirometry is a safe procedure and allows you to use it without restrictions. From side effects you can call a slight dizziness during the procedure, but this phenomenon disappears 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, pulmonary hemorrhage, pneumothorax, hypertension, and poor blood clotting. Age over 75 years is also a contraindication.

We considered the FEV1 norm and other indicators.