Today, let’s talk about respiratory function.
Spirography is a method of recording changes in lung volume, which are registered during breathing.
The very measurement of lung volumes and air streams is called spirometry, and the resulting curve is a spirogram, by which the volume of air inhaled and exhaled during each respiration cycle can be specified. Briefly, this method is called – PFT (pulmonary function test).
Spirometry allows you to assess the degree of obstruction, its reversibility and variability, which is taken into account when determining the severity of the disease and, correspondingly, the treatment plan.
When is Spirography Necessary?
- cough for 3-4 weeks;
- a feeling of incomplete inspiration, shortness of breath;
- attacks of suffocation (including accompanied by whistles and wheezing);
- frequent exacerbations of obstructive bronchitis;
- control over the treatment of bronchial asthma;
- long-term experience of smoking;
- work in enterprises with a high degree of air pollution;
- hereditary predisposition to bronchopulmonary diseases or allergic diseases.
Spirometry has no absolute contraindications, but there are a number of limitations to its conduct:
- the general severe health condition;
- patients with developed pneumothorax (presence of air in the chest cavity) and within 2 weeks after its resolution;
- in the first 2 weeks after the myocardial infarction development;
- after ophthalmic and cavitary operations;
- with a long-lasting ongoing hemoptysis;
- stable angina;
- a high degree of poorly controlled arterial hypertension (high blood pressure), hypertensive crisis.
How is Spirometry Performed?
For spirography, the patient’s preparation is not almost required, there are only a few rules:
- such an examination is best done in the morning, on an empty stomach, or after a light breakfast;
- smoking should be excluded for at least 1 hour, alcohol consumption – 4 hours before the study, significant physical activity – 30 minutes before the study;
- within 2 hours before the study it is not recommended to have abundant food intake;
- if the patient takes bronchodilators (salbutamol, berodual, etc.), they should be withdrawn at least for 6 hours before the planned examination;
- the patient’s clothing should allow him to breathe freely, without hampering the chest and abdomen;
- The patient should not tilt the head or stretch the neck, he should also avoid tilting the patient’s body forward when exhaling.
Features of Spirometry in Children
Spirometry can be performed in children on average from 4-5 years old. In children older than 6 years this procedure is mandatory for diagnosis and evaluation of severity and control of asthma.
Before beginning the study, the child should be explained in a plain language what he should do. Good results are obtained using a visual “image”. Even if the first attempts were unsuccessful, continuing the research in most cases allows the child to get used to the situation and better perform a breathing pattern.
The room where spirometry is conducted should be adapted for children. The most important moment, in this case, is the psychological calmness of the child, he should feel comfortable. In the laboratory dealing with the examination of young children, there must be a very benevolent atmosphere, toys suitable for age can be used.
Evaluation of the results of the spirographic research is carried out by comparing the actual values with the norms.
As a result, according to the spirogram, we can see obstruction, restriction, or a mixed type of disturbance. In healthy people, all the studied indicators (FEV1 – the volume of forced expiration in 1 second, the vital capacity of the lungs, FVC is the forced vital capacity of the lungs, the Tiffeneau index is the ratio of FEV1 / the vital capacity of the lungs) is usually above 80% of the normative indicators.
The value below 70% of the norm is a sign of pathology. The range from 80% to 70% should be treated individually. For older age groups, such indicators do not be characterized as a pathology. In children, young and middle-aged patients, they may indicate initial signs of obstruction.
Diagnostically significant indicators in children, at present, do not differ from those in adults.
Also, in addition to basic spirometry, a supplemental spirographic examination is performed with a medicamental loading, in another – a test with a bronchodilator.
That is, first the usual spirometry is performed, then the patient inhales the bronchodilator (most often it is salbutamol at a dose of 400 mcg in adults and 200 mcg in children), and spirometry is repeated after 15 minutes.
So, these post-dilation values (i.e. the changes in the main indicators after inhaling the bronchodilator drug) play a huge role for the doctor in finding the answer to the question whether the obstruction is reversible or not?
According to the latest recommendations of the ERS (European Respiratory Society), the change in FEV1 and/or FVC allows a rather accurate determination of the reversible airway obstruction.
A bronchodilator test is considered positive if, after the bronchodilator inhalation, the change in FEV1 and/or FVC is more than 12%, and the absolute increase is more than 200 ml.