The Contrastive Research Of Dilatation Of Airway Spasm By Salbutamol In Asthma Patients

Asthma is a chronic bronchial disease with reiteratively bronchial constriction and airway inflammation.in the during of asthma, if the bronchial constriction is the most important reason, constriction disappeare, symptom will be alleviative.The constriction of airway sooth muscle will lead outbreak of asthma whether in acute spasm or chronic course of disease.Bronhodilation test is a sort of pulmonary function test (PFT) which use bronchodilator drug to dilate the narrow airways. With the degree of airways dilatation, we can judge the state of airway reactivity. Therefore, bronchodilation test is often used as an assist method to diagnose asthma. Now the indexes of judge bronchodilation test are forced expiratory flow (PEF). However, according to the current standard of bronchodilation test positive, the diagnosis rate of asthma is only ≦70％.In order to raise the positive rate of diagnosing asthma, people investigate other indexes, such as maximal midexpiratory flow (MMEF), forced vital capacity (FVC), expiration of 50% FVC (V50), expiration of 25% FVC (V25), airway resistance (Raw), specific airway conductance (sGaw), etc. After performing regular bronchodilation test., asthma patients were examined PFT when 15 minutes, 30 minutes, 1 hour, 2 hour, respectively. The indexes include FVC, FEV1, PEF, MMEF, and V50and V25. We found that straight line of slope indexes which reflecting the function of large airways including FVC, FEV1, and PEF is higher than indexes which reflecting the function of small airway including MMEF,V50, and V25. It means large airways can resume better after inhale the bronchpdilator drug in the same time.Below are the possible reasons: First, there are more airway sooth muscles in the small airway on the same area, then concentration of drug will decent.Second, the air inspired to human body diffuses from bronchus which area is only 5 cm2 into broad regions of about 80cm2. The speed of airflow gets slower while running from one grade to next one. The collosol diameter of salbutamol aerosol is about 4-5 μm It is easy to deposit in large airways because of inertia halt and gravity sedimentation. The inertia halt is that the inertia of particle is proportional to its mass and speed of running according to Newton Law. In the throat, bronchus and and it's branches, the airway directions suddenly change and the speed of airflow is fast and internal pressure is low. So particles are apt to struck airflow is at the state of turbulent in large airways, which accelerate the particles to deposit. This supports the viewpoint that large airways dilate first.Last, there are more serious in the small airway, then the mending will be affected.In conclusion, our results may be helpful to raise the positive rate of bronchodilation test and guide to therapy of asthma.