The lung volume measurement included tidal volume, supplemental inspiratory volume, supplemental expiratory volume, residual volume, deep inspiratory volume, vital capacity, functional residual capacity, and total lung volume. Lung ventilation refers to the process of gas exchange between the lungs and the outside atmosphere. During lung ventilation, lung capacity changes correspondingly with changes in respiratory motility. The lung capacity at different times was measured to assess the pros and cons of lung function.

Basic Information

Specialist classification: Respiratory examination classification: pulmonary function test

Applicable gender: whether men and women apply fasting: not fasting

Reminder: Quiet rest before the determination of resting ventilation, should be carried out completely under basal metabolism, and the surrounding environment is quiet. Requires a smooth breathing. Normal value

(1) Tidal volume (VT) This refers to the amount of air that is inhaled or exhaled each time when breathing calmly.

The normal reference value is 500ML (adult).

(2) Inspiratory volume (IRV) refers to the maximum amount of air that is inhaled after forced inhalation.

The normal reference value M (male) is about 2.16L F (female) about 1.5L.

(3) Supplemental expiratory volume (ERV) refers to the maximum amount of air exhaled after a brief exhalation.

The normal reference value M (male) is about 0.9L and F (female) is about 0.56L.

(4) The amount of residual gas (RV) is the amount of residual gas that cannot be exhaled in the lung after supplemental exhalation.

The normal reference value M (male) 1.380 + 0.631 LF (female) 1.301 + 0.466 L.

(5) Deep inspiratory volume (IC) refers to the maximum amount of gas that can be inhaled after a brief exhalation (tidal volume + supplemental inspiratory volume).

(6) The maximum (all) volume of vital capacity (VC) that can be exhaled after maximal inhalation. (tidal volume + supplemental inspiratory volume + supplemental expiratory volume).

The normal reference value M (male) is about 3.5L and F (female) is about 2.4L.

(7) Functional residual capacity (FRC) refers to the amount of gas contained in the lungs after calm exhalation (replenishment of exhaled breath + residual gas volume).

The normal reference value M (male) 2.77 + 0.8 LF (female) 1.86 + 0.5L.

Clinical significance

Abnormal results:

Less than 80% is abnormal. When suffering from chest deformity, limited chest and lung expansion, airway obstruction, lung injury, chronic bronchitis, emphysema, pneumonia and other diseases, the lung capacity decreased. If the lung capacity and total lung volume decrease at the same time, it means that the ventilation volume is reduced. Healthy people increase the alveolar aging with age, expand due to decreased elasticity, and the residual gas and functional residual capacity increase accordingly. If both abnormalities increase at the same time, it means airway obstructive ventilation, such as chronic obstructive emphysema.

Need to check the crowd:

Patients with confirmed thoracic deformity, limited chest and lung expansion, airway obstruction, lung injury, chronic bronchitis, emphysema, pneumonia and other diseases are needed.

Low results may be diseases: emphysema, obstructive emphysema, lung injury precautions

Preparation before inspection:

Before the examination, the subjects should be explained in detail about the inspection methods and essentials, and adaptive training should be done.

Requirements for inspection:

1. Quiet rest before resting ventilation measurement, should be carried out completely under basal metabolic state, and the surrounding environment is quiet. Requires a smooth breathing.

2, patients should eliminate tension, with the doctor's examination, so as not to affect the results of the examination.

Not suitable for checking people:

1, severe heart and lung disease, the body is weak.

2, mental abnormalities or can not be well coordinated.

Inspection process

1. The mouth of the subject contains an interface device, which fixes the nose clip and makes a calm breath through the mouth. When the tidal curve is stable, the force is maximally inhaled at the end of the calming end of expiration, and the maximum exhalation is then applied. At the same time, the recorder was recorded in the whole process to record the lung volume map.

2. According to the definition of lung volume composition, the measured values ​​of VT, VC, IC and ERV are measured on the lung volume map.

3. Functional residual gas (FRC) cannot be measured directly on the lung volume map. It is based on the law of conservation of mass, a certain amount of indicating the principle that the gas is invariably in the lungs before and after the repeated connection of the sealed tester, and the total amount is unchanged, and the FRC is calculated indirectly. At the time of testing, you should pay attention to the timing of starting repeated breathing, and it is advisable to start the breath immediately after the end of the exhalation, and accurately measure the concentration of the indicated gas before and after the balance, otherwise the calculation accuracy will be affected.

Calculation method: Assume that the total volume of the spirometer pipe and the measuring cylinder is B, the indicator gas (such as 氦) used before the test is F, and the concentration after the repeated breathing balance is F1, the basic derivation formula for calculating the FRC is as follows:

B × F = (FRC + B) × F1

4. After calculating the residual function, you can calculate RV and TLC as follows:

RV=FRC-ERV, TLC=VC+RV

Not suitable for the crowd

Taboo people:

1, severe heart and lung disease, the body is weak.

2, mental abnormalities or can not be well coordinated.

Adverse reactions and risks

Generally no complications and harm.