Human respiration occurs in two important stages - external and tissue. Moreover, the system of pathways for conducting air from the nasal cavity to the alveolar tree of the lungs is only the first of them. And if we can see the anatomical structure of organs using radiation diagnostic methods (X-ray, fluorography, ultrasound, computed, magnetic resonance imaging), then completely different devices help us assess the functional state.
The essence of the method
Many patients of a pulmonologist or family therapist, having received a referral to this study, are wondering: "Spirography - what is it?" Let's try to figure this out together.
The fact is that this analysis is prescribed for both people with diseases of the respiratory system and completely healthy, even athletes, and therefore there is such a misunderstanding. So, spirography of the lungs is an important method of studying the
function of external respiration, which allows one to determine the viability of these organs from the obtained indicators to provide the whole body with oxygen and sufficient removal of carbon dioxide. All data is recorded graphically, that is, on paper, and the result becomes known instantly after analysis. Spirography indicators give the doctor important information about the conductivity of the respiratory tract and the ventilation capacity of the lungs, which allows him to identify the link of the disorder and the possibility of reversibility of pathological changes in it. In addition, you can evaluate the effectiveness of the drug by removing the spirogram before and after taking it. So, for example, they conduct a simple test with bronchodilators in cases of suspected asthma.
Conditions
So, we figured out the concept of spirography. How this study is conducted is also important to know. It is prescribed, as a rule, in the morning or afternoon, preferably on an empty stomach. However, it is also possible to conduct it after a light breakfast, provided that at least 2 hours have passed since the meal. First, so that the indicators of the analysis do not give false information, the patient is allowed to rest physically and emotionally for 15 minutes while sitting. During this time, the heart rate and respiratory movements should normalize, which means that the study will show a real picture of his health. It is also important that the patient does not take drugs with a bronchodilating effect during the last 6-12 hours.
Equipment
Next, the patient is seated near the table on which the spirograph is placed, a special clip is put on the nose so that all the air comes out exclusively through the mouth. Then it is connected to the device by means of a mouthpiece and offered to fulfill the doctor's recommendations for measuring all the necessary indicators. As a rule, modern spirographs process data independently, that is, automatically, due to which the result appears instantly like a check from a cash register: this is how spirography ends. The norm of all indicators is also issued by the device by calculating them relative to the gender and age of the patient. Next, the doctor, comparing them with each other, reveals the localization of the violation. It is also possible to conduct tests after the introduction of bronchodilators, which reveals the presence or absence of their effect. Thus, this study is an important instrumental method for diagnosing a patient’s health or illness.
Indications for research
It is important to know about the examination called spirography that this analysis, like any other, has certain indications for it. Namely:
- upcoming surgery (to assess risk during surgery);
- identified wheezing, coughing, shortness of breath and other symptoms of damage to the respiratory system during the initial examination of the patient;
- diagnosis of the degree, stage of an already identified pulmonological disease, accompanied by bronchial obstruction or severe organic and functional disorders of the ventilation system (COPD, bronchial asthma, chronic bronchitis), as well as an assessment of the effectiveness of the prescribed therapy;
- determination of the prognosis of life, working ability and professional suitability of a patient with diagnosed lung diseases;
- extrapulmonary diseases, often accompanied by dysfunction of the respiratory system (cardiovascular pathology, diabetes mellitus, systemic lesions of the connective tissue).
Other indications
In addition, periodic spirography of the lungs should be performed in patients at risk for diseases of the respiratory system. These are smokers with many years of experience, workers in heavy industry and other industries, one way or another falling into the category of hazardous production. On the contrary, contraindications to this examination are mental, acute infectious diseases, the patient’s serious condition, pulmonary tuberculosis with bacilli, hemoptysis, and the threat of miscarriage during pregnancy.
Analysis structure
So, we found out that indicators of the state of the human respiratory system are recorded through such an examination as spirography. Basically, they are functional, that is, they reflect not organic disturbances, but ventilation ability.
In more detail, these include the frequency of respiratory movements (number per minute), total tidal volume (i.e. the amount of air that can enter the lungs in one breath), minute volume (similar to the previous one, only counts for one minute), vital lung capacity for inhalation and exhalation (measures the maximum capacity of organs), oxygen consumption and utilization rate, forced inspiratory and expiratory volumes (performed with chest muscle tension), air velocity, Tiffno index ( measured by the ratio of forced expiratory volume to lung capacity in 1 second) and some others. All these indicators help the doctor to compose a holistic informative picture about the condition of the air paths and sufficient gas exchange. So, the assimilation of oxygen occurs by diffusing it from the alveolar sacs of the lungs into the blood and is disturbed by structural damage to the lungs.
Role in diagnosis
Spirography for bronchial asthma has its own characteristics both in the methodology and in the interpretation of the results.
An important role for the diagnosis of this disease is played by the test of forced inspiration and expiration, on the basis of which a schedule is automatically constructed based on the type of loop - “volume-flow”. It is in its form that in the presence of respiratory failure its type is determined: restrictive (associated with organic damage to the lungs), obstructive (due to impaired air flow through the bronchial or alveolar tree), or mixed. Also, the curve obtained can be used to trace a decrease in the peak forced expiratory flow rate in the FVC interval of 25-75%, as well as the volume of forced inspiration. This visually demonstrates the pathogenesis of asthma, in which there is a sudden spasm of the distal parts of the bronchi, which is manifested by attacks of suffocation.
Tests
In the obstructive type of respiratory failure , it is also important to determine the degree of reversibility of changes, which allows you to make a diagnosis and the severity of the disease. So, the most common test is a pharmacological test with short-acting B2-adrenergic agonists, which include the drug “Salbutamol”. To carry out it in 6 hours, the cancellation of other drugs of a similar action is prescribed, then the volume-flow curve is recorded. Next, the patient makes one or two inhalations with the drug, and already after 15 minutes to half an hour after this, repeated spirography is performed. What is this type of obstruction, let you know the changes in the indicators of analysis. So, if they increase by more than 15% of the initial results, the test is considered positive.
Another method
Since patients with asthma must continuously monitor their health, there is another method for calculating the flow-volume curve - pneumotachography. Compared with spirography, it is simpler, which means that it is suitable for independent use by the patient at home. This allows a person to monitor the functioning of his respiratory system on a daily basis, and also greatly simplifies the work of the doctor, since he most accurately reflects the dynamics of the disease in the intervals between visits to a medical institution. The pneumotachograph is also a tube with a removable mouthpiece connecting the patient to a computing device, which is automatically able to calculate many functional indicators and the flow-volume curve.
Conclusion
Of course, only a pulmonologist directs functional tests to tests, since there are strict indications for them. To begin with, of course, he must obtain the informed consent of the patient, and therefore he will certainly tell you where to do spirography, what it is and what are the purposes of its appointment. It is extremely important to establish a trusting relationship between the doctor and the patient, as well as create a favorable environment for the test, since only with the psychological comfort of the patient the results of the study will be reliable. And already on the spot, the laboratory assistant taking the analysis will explain the rules for conducting the tests so that the results not only turn out to be correct, but also help the doctor in diagnosing the patient’s disease.