Maximum mid-expiratory flow

The maximal mid-expiratory flow curve (MMEF, MMF) is the average flow rate of 25% to 75% of the vital capacity exhaled by the FVC curve. Forcedvitalcapacity (FVC) used to be called time vital capacity, which is the total amount of gas that can be exhaled with maximum exertion and speed after deep exhalation to TLC. The initial expiratory phase of FVC has a fast expiratory speed, which is greatly affected by subjective exertion factors and is difficult to grasp. At the end, the last part of the curve is in the low lung capacity, the lung elastic retraction force is reduced, the airway diameter is reduced, the flow rate is low, and it is often not completed correctly for those who have difficulty breathing. Basic Information Specialist classification: Respiratory examination classification: pulmonary function test Applicable gender: whether men and women apply fasting: not fasting Tips: Keep quiet for a while. Normal value Normal men are about 34,452 ± 1160 ml / s and women are about 2,836 ± 946 ml / s. Clinical significance Abnormal result The initial expiratory phase of FVC has a fast expiratory speed, which is greatly affected by subjective exertion factors and is difficult to grasp. At the end, the last part of the curve is in the low lung capacity, the lung elastic retraction force is reduced, the airway diameter is reduced, the flow rate is low, and it is often not completed correctly for those who have difficulty breathing. The MMF mainly depends on the non-force-dependent part of FVC, that is, after the expiratory flow reaches a certain limit with the force, although the force is continued, the force flow is fixed and has nothing to do with the force. Changes in low lung volume flow, including MMF, are affected by small airway diameters, and flow reduction reflects small airway obstruction. The study found that small airway disease when FEV1.0, FEV1.0/FVC% and airway resistance were normal, MMF can be reduced, indicating that MMF better than FEV1.0/FVC% can reflect small airway obstruction. The maximum ventilation can reflect the severity of airway obstruction, as well as the patient's respiratory reserve, muscle strength and power level, which can be used as a preoperative evaluation. The reduction is seen in (1) increased airway resistance such as various chronic obstructive pulmonary diseases, bronchial asthma or bronchial tumors. (2) lung tissue damage such as pneumonia, tuberculosis, alveolar hemorrhage, pulmonary edema, pulmonary interstitial fibrosis. (3) thoracic and pleural lesions such as severe posterior scoliosis, rib fractures, pneumothorax, and massive pleural effusion. (4) Nervous system and respiratory muscle activity disorders such as anesthesia, encephalitis, poliomyelitis and myasthenia gravis. It is necessary to check the situation of the decrease in lung capacity caused by small airway obstruction and the change in lung volume flow. Or obstructive dyspnea. Low results may be diseases: tuberculosis, bronchial asthma considerations Taboo before inspection: Keep quiet for a while. Attention during the examination: standing position, with the doctor. Inspection process Calculation method: divide the FVC curve into four equal parts in parallel and perpendicular to the two points, and take the lung volume of the middle 2/4 segment and the exhalation time (mid-expiratoeytime, MET) used. The ratio. Normal men are about 34,452 ± 1160 ml / s and women are about 2,836 ± 946 ml / s. Not suitable for the crowd Severe cardiopulmonary disease and hemoptysis should be avoided because it will aggravate the condition. Adverse reactions and risks The test is non-invasive and does not cause serious complications or other hazards.