Lung volume

Lung volume refers to the amount of gas contained in the lungs. It assists in the evaluation of lung function by measuring changes in volume caused by respiratory movements of different magnitudes. It is suitable for bronchopulmonary diseases, thoracic and pleural diseases, and neuromuscular diseases. Basic Information Specialist classification: Respiratory examination classification: pulmonary function test Applicable gender: whether men and women apply fasting: not fasting Tips: For patients with long-term smoking, patients taking drugs such as diastolic trachea need to seek medical advice. Normal value 1. The amount of tidal volume (VT) per inhaled or exhaled on a calm exhalation basis. The normal person is about 500ml. 2. Inspiratory volume (IRV) The maximum amount of air that can be inhaled after inhaling. The normal value is 2100ml for men and 1500ml for women. 3. Replenishing the amount of breath (IRV) After exhaling breath, the maximum amount of breath that can be exhaled by forced exhalation. Normally accounts for about 15% of the total lungs. 4. Residual gas volume (RV) The amount of gas remaining in the lungs after deep exhalation. Normally accounts for about 25% of the total lungs. About 1,500 ml of adult males in China and about 1000 ml of females. 5. Deep inspiratory volume (IC) The maximum amount of air that can be inhaled after exhalation. Normal accounts for about 60% of the total lungs. 6. Functional residual capacity (FRC) The amount of air contained in the lungs after a brief exhalation. Normal accounts for about 40% of the total lungs, about 2300ml for men and about 1600ml for women. 7. Vital capacity (VC) The amount of gas that can be exhaled after maximizing exhalation after inhaling. Long adults account for about 75% of total lungs, about 3,500 ml for men in China and 2,500 ml for women. 8. Total amount of gas (TLC) The amount of gas contained in the lungs after deep inhalation. The adult male in China is about 5000ml, and the female is about 3500ml. Clinical significance 1. Reduced lung capacity, mainly in the following situations: 1 lung restrictive diseases, such as lung tumors, lung inflammation, atelectasis or fibrosis, cause lung tissue compression, atrophy or normal lung tissue replaced by lesions. 2 thoracic activity disorders, such as rheumatoid arthritis, poliomyelitis, spinal deformity and other diseases affecting thoracic expansion or contraction. 3 large volume lung resection. 2. The amount of functional residual gas increases, as shown in the following cases: 1 The elastic retraction force of the lung tissue is weakened, such as emphysema; 2 airway is partially blocked, especially when exhaling, such as bronchial asthma; 3 compensated emphysema after lung resection; 4 thoracic deformity or severe spinal deformity, causing excessive alveolar swelling and emphysema. 3. Residual gas volume / lung volume ratio increased, may be caused by an increase in the absolute value of residual gas (such as asthma or emphysema), or a decrease in total lung volume (such as various restrictive lung diseases or pulmonary congestion). 4. The total amount of lungs is reduced. It is found in a wide range of lung diseases, such as pulmonary edema, pulmonary congestion, atelectasis, lung tumors, and restrictive ventilatory disorders. It is also seen in pneumothorax or pleural effusion causing compression of lung tissue, which in turn affects the lungs. Expansion. Low results may be diseases: idiopathic pulmonary fibrosis, pulmonary eosinophilic histiocytosis, idiopathic obstructive bronchiolitis with organizing pneumonia, idiopathic pulmonary fibrosis in the elderly, silicosis, respiratory respiration Bronchial-related interstitial lung disease, respiratory bronchiolitis, interstitial lung disease considerations Requirements for inspection: 1. In the test, please pay attention to the elimination of air leaks (most commonly without lip closure, no upper nose clip or loose nose clip), glottic closure when exhaling, exhalation pause, double inhalation, cough and other factors caused by the lungs The impact of functional outcomes. 2. Extrapolation volume can be automatically calculated in most current pulmonary function meters, which is a good indicator to evaluate the early burst of exhalation force. In some simple spirometers, this indicator may not be displayed. 3. After exhaling at the beginning of forced exhalation, due to the non-force dependence of exhalation flow in the middle and late exhalation, the subject can be instructed to maintain only exhalation, but the body can be moderately relaxed without being too nervous. 4. It is best to observe the time volume curve and the flow volume curve simultaneously during the test to know in real time whether the subject's breathing meets the quality control requirements. 5. Some patients with severe airway obstruction may have an expiratory time of up to 20 seconds and still have no expiratory volume platform. At this time, the patient's condition must be closely observed to prevent it from syncing or falling. Can interrupt exhalation in due course. 6. If the degree of cooperation of some subjects with forced breathing is not good, it will affect the test results (especially peak flow and vital capacity), which should be specified in the results report for clinical reference only. 7. Repeatability testing is very helpful for the quality control of the subjects, but not all of the repetitive tests used meet the A-level criteria. Some subjects may only have C, D or F grades despite their best efforts. The lung function test cannot be abandoned, but it should be stated in the report to remind the clinician. 8. Multiple testers can print overlapping time volume curves and flow volume curves, which is helpful for the evaluation of repeatability. 9. Due to the intra-day variation of the individual, the afternoon measurement value can be higher than the morning, so if longitudinal comparison is needed (such as comparison before and after treatment), it is best to perform within ±2hr of the same time period. 10. If you use a breathing filter, you should know in detail whether the resistance of the filter is sufficient to affect the respiratory flow. 11. The selection of the normal reference value is the basis for evaluating whether the lung function is normal. Each laboratory should try to select the normal reference value that is suitable for it (such as the region, the test population, the detection method, etc.). This is very important for correct result analysis. The National Compendium of Normal Lung Function, edited by Professor Mu Kuijin and Professor Liu Shizhen, can be used as a reference. If the reference value recommended by the European Respiratory Society (ERS) for Asians is used, the correction value should be considered. 12. Subjects with higher airway sensitivity may induce airway spasm when repeated repeated forced breathing, thus reducing respiratory volume and flow, and repeatability criteria (such as the best 2 FVC described above) And the variation of FEV1 <5% or <0.2L is impossible to achieve. It should be stated in the results report. Preparation before inspection: 1, ask the subject's medical history, smoking history, recent medication, etc., to exclude contraindications for forced lung function testing. 2. Explain the test procedure and precautions in detail to the subject. 3, the instructor to demonstrate demonstration, including complete inhalation, explosive exhalation and continued continuous exhalation, can be combined with language and body movements, and strive to allow the subject to fully understand the detection movement. Not suitable for people: For patients with long-term smoking, patients taking drugs such as diastolic trachea need to seek medical advice. Inspection process 1. Instructor: 1 Ask the subject's medical history, smoking history, recent medication, etc., and exclude contraindications for forced lung function testing (described later). 2 Explain the test procedure and precautions in detail to the subject. 3 The instructor gave a demonstration, including complete inhalation, explosive exhalation, and continued continuous exhalation. It can be combined with language and body movements to ensure that the subject fully understands the detection movement. 4 Continue to prompt and encourage the subject as the subject is tested. 2. Subjects: 1 The subject takes a sitting position and sits up straight without a backrest, with both feet on the ground and eyes looking straight, avoiding the head leaning back or leaning down. 2 Practice the above breathing exercises and master the essentials. 3 mouth bite device, tightly wrapped around the mouthpiece with the lip to ensure no air leaks, upper nose clip. 4 After breathing calmly, completely inhale, then exhale vigorously, quickly and completely, and ask for explosive force to exhale. There is no hesitation at the beginning, and the degree of exertion in the middle and late exhalation can be slightly reduced, but there is no interruption in the whole exhalation until exhalation. Complete, avoid coughing or double inhalation. 5 Quickly inhale to complete after exhalation. Test results meet acceptable quality control standards. 6 After a short break (depending on the patient's condition), repeat the above 3, 4, and 5 measurements, and complete at least 3 measurements, generally no more than 8 times. Not suitable for the crowd Contrained people: For long-term smoking patients, patients taking drugs such as diastolic trachea need to seek medical advice. Adverse reactions and risks No complications or harm.