Pulmonary function tests.
Pulmonary function test is one of the necessary tests for respiratory system diseases, which is important for early detection of lung and airway lesions, assessment of disease severity and prognosis, evaluation of the efficacy of drugs or other treatments, identification of the causes of dyspnea, diagnosis of lesion sites, assessment of lung function for tolerance to surgery or labor intensity and monitoring of critically ill patients.
Pulmonary function tests include ventilation, ventilation, respiratory regulation and pulmonary circulation, etc. There are many items and indexes to be measured. In the past, pulmonary function instruments were mainly based on mechanical and chemical methods, which were tedious, time-consuming and laborious, and had large testing errors, limiting their wide application in clinical practice and limited knowledge of medical workers. In recent years, with the development of science and technology, the emergence of new testing techniques, especially the application of electronic computers, has led to the great development of pulmonary function testing technology, and its importance in clinical practice has been increasingly emphasized.
Pulmonary function tests are mainly used for the following purposes.
1, early detection of lung and respiratory tract pathology.
2.Identify the cause of dyspnea and determine the site of airway obstruction.
3.To assess the severity of lung diseases.
4.To assess the surgical tolerance and the possibility of postoperative complications.
5.Assessment of health physical examination, labor intensity and tolerance.
6.Custody of critically ill patients, etc.
Features.
1.Pulmonary function test is a physical examination method, without any damage to the body, pain and discomfort.
2.Pulmonary function test has the advantages of high sensitivity, convenient repeat testing and easy acceptance by patients.
3.Compared with X-ray chest X-ray, CT and other examinations, pulmonary function test focuses more on understanding the functional changes of the lungs, an important examination tool for respiratory system diseases.
Importance.
1.Diagnose the patient’s respiratory function status and confirm the nature and degree of lung function damage.
2, to confirm the diagnosis of COPD must be performed pulmonary function tests.
3. Pulmonary function tests help clinicians to clarify the severity of COPD and to develop appropriate treatment plans according to the severity of the disease.
Subjects.
1.People with repeated upper respiratory tract infections – observe whether there is damage to lung function
2.Smoking history and long-term cough – to see if small airway function is altered
3, seasonal coughing and wheezing attacks – to see if they have asthma
4, chronic bronchitis regular review – to monitor the development of the disease process
5, abnormal chest X-ray – to determine the degree of lung function damage
6.Anesthesia, risk assessment of surgical procedures, and prediction of postoperative recovery
Asthmatic patients.
Pulmonary function tests during a typical asthma attack first show obstructive lesions, but not all obstructive lesions are asthma. Further confirmation of the diagnosis can be made with an airway dilation test to confirm asthma. In atypical asthma or asthma in remission or with a negative airway dilation test, an airway provocation test may be performed to confirm the diagnosis of asthma, if appropriate.
Children with.
1. recurrent cough or with wheezing.
2. Cough lasting more than 2 to 3 weeks and ineffective antibiotic treatment.
3. Recurrent “colds” that progress to the lower respiratory tract and last more than 10 days.
4.Evaluation of the condition of the child with asthma.
5.Acute attacks of choking cough, hoarseness and dyspnea.
6. Early differentiation of acute bronchitis, pneumonia and asthma in infants and children.
7, other respiratory diseases.
Performance.
The manifestations of respiratory system diseases in pulmonary function tests are mainly
1, obstructive lesions: refers to changes in airflow obstruction due to various factors causing narrowing of the airways, of which asthma is the most obvious.
2, restrictive lesions: refers to the lung respiratory movement is restricted and there is a change of reduced lung ventilation, such as emphysema, pleurisy and fluid pneumothorax, etc., all have different degrees of reduced lung ventilation.
3, mixed lesions: refers to both obstructive and restrictive lesions, such as chronic obstructive pulmonary disease and advanced asthma, pneumoconiosis, pediatric bronchopneumonia, etc.
Detection of.
1.Because the nose is clamped, so you should keep breathing through the mouth
2.Tighten the mouth as much as possible to ensure no air leakage during the test
3, as far as possible with the operator’s command, immediately do exhalation and inhalation action
4.Inhale as much as possible, then exhale with maximum force and fastest speed
Physical parameters.
1.Volume: the size of the volume of breathing gas, mainly reflecting the breathing capacity.
2, flow rate (flow): the size of the volume of respiratory gas per unit time, reflecting the respiratory capacity and airway patency.
3, time: the time relationship of breathing, is an important parameter of dynamic pulmonary function testing, because most of the current pulmonary function instrument are automatically controlled by computer, so the breathing time can be automatically recorded.
4, pressure: the driving pressure required to breathe, reflecting the respiratory resistance and thoracic lung compliance.
5.Gas composition: the measurement of relevant gases such as oxygen, carbon dioxide, carbon monoxide, nitrogen and other marked gas concentrations or partial pressures during respiration.
Role.
Pulmonary function tests can only show changes in the physiology and pathophysiology of the lung o but cannot suggest the pathogenic diagnosis and the site of lesion occurrence can only show the pathophysiological changes of fairly extensive lesions and cannot suggest functional changes in minor limited lesions. Therefore, it cannot replace history, physical examination, and lung x-ray laboratory tests. o It can only play a complementary role when these important data are available.
The total volume of air held in the lungs is approximately 5.0 L in a normal adult. It varies according to age p gender p height and weight. The volume of air entering or exhaled per unit time is called flow. The average thickness of the gas exchange membrane (also known as the blood-gas barrier) between the blood capillaries of the alveolar gas lungs is less than 1/1000 mmo area of about 70-100 m. On both sides of the membrane the partial pressure of the gas (oxygen and carbon dioxide) diffuses differently from high partial pressure to low partial pressure, and oxygen enters the blood from the alveoli and carbon dioxide is discharged from the blood to the alveoli, constituting an effective The diffusion of gases from the alveoli into the bloodstream and carbon dioxide from the bloodstream to the alveoli constitutes effective gas exchange. Oxygen is transported to the tissues and organs through the blood circulation. o Carbon dioxide produced by the tissues and organs is transported by the blood to the lungs and expelled from the body.