Evaluation Of Small Airway Function In Bronchial Asthma

Objective:By comparing pulmonary function test(PFT)with impulse oscillometry lung function(IOS)in patients with bronchial asthma,the coexistence of large and small airway dysfunctions,degree of damages,and variation rules of airway resistance of such patients are studied.The early small airway dysfunction is evaluated and the sensitivity of IOS detecting small airway function is explored,so as to approach the clinical value of asthma medication,and to provide reference and evidence for the extensive clinical application of IOS.Methods:96 patients with bronchial asthma visiting respiratory clinic of Shanghai Pulmonary Hospital from September 2016 to October 2019 were selected as the subjects included in the study.The selection criteria are,without gender and age limitation,including all the patients diagnosed as acute bronchial asthma in accordance with the"Guidelines for the Prevention and Treatment of Bronchial Asthma(definition,diagnosis,treatment and management plan of bronchial asthma)" issued by Respiratory Disease Branch of Asthma Group under the Chinese Medical Association,but excluding those with bronchiectasis,COPD and thoracic deformity,other diseases affecting pulmonary function,such as pleural effusion,cardiovascular and cerebrovascular diseases and sports system diseases.Those patients who could successfully complete IOS and PFT lung function tests,mild and moderate patients with acute asthma attack were selected,severe and critical patients were not included in the study.86 healthy people at the same age group with no history of chronic cardiopulmonary disease and no recent record of respiratory tract infection disease were selected as control group.The gender and age of the subjects were recorded and their height and weight were measured.In the sequence of IOS detection first and PFT detection later,IOS detection took 3 0-45 s each time and repeated 3-4 times,with the interval of lmin,to obtain the optimum value.PFT detection was repeated 3 times in total,with the interval of 10min,The difference between the best and second best values of The Group FVC and 1 Second volume(FEV1)is less than 0.15L.group error less than 5%,to obtain the optimum curve(FVC maximum,steep ascending branch,full breath,smooth curve with clear starting and ending point).Lung function measurement of IOS and PFT were carried out at the same time,respectively in the acute stage and remission stage of adult asthma patients,as well as the healthy control group.The parameters of IOS and PFT were compared and analyzed,with R5?R20?R5-R20?AR5-R20?X5?AX standing for IOS and FEV3/FVC?MEF25?MEF50?MEF75?MMEF75/25?RV?TLC?RV/TLC?Rtot?Reff standing for PFT.The percentage of PFT parameters in the predicted value was expressed by%pre.Results:1.There were no significant differences between the asthma group and the healthy group in age(53.78±12.57 vs 50.77±8.99 years old,P>0.05),gender(41/55 vs 45/41 male/female,P>0.05),height(161.51±8.96 vs 162.90±7.48 cm,P>0.05),weight(62.27±11.73 vs 64.67±10.58 kg,P>0.05)and other basic data.2.Comparison between the acute attack period of asthma group and the healthy control group:the IOS parameters R5(0.54± 0.25 vs 0.35 ± 0.07,P<0.001)?R20(0.42±0.19 vs 0.31±0.06,P<0.001)?R5-R20(0.12±0.08 vs 0.04±0.03,P<0.001)?AR5-R20(29.69±15.06vs 12.03±9.45,P<0.001)?AX(2.01±2.71 vs 0.33±0.25,P<0.001)of the acute asthma group were significantly higher than that of healthy group,and the parameter X5 was significantly lower than that of healthy group.PFT parameters RV%pre(137.80±39.25 vs 107.04±19.03,P<0.001)?RV/TLC%pre(128.83±24.25 vs 106.69±15.04,P<0.001)?FRC%pre(115.14±25.45 vs 103.67±17.89,P<0.001)?Rtot%pre(173.04±80.94 vs 99.78±27.54,P<0.001)and Reff%pre(156.91±70.25 vs 97.94±26.26,P<0.001)were significantly higher than those in the healthy control group.Parameters FEV3/FVC%pre(98.13±5.61 vs 100.34±2.94,P<0.001)?MEF75%pre(70.34±23.74 vs 96.54±18.54,P<0.001)?MEF50%pre(66.75±28.46 vs 95.56±21.18,P<0.001)?MEF25%pre(55.67±28.41 vs 82.43±28.21,P<0.001)?MMEF75/25%pre(54.19±23.47 vs 84.37±18.79,P<0.001)and IC%pre(83.31±21.86 vs 93.37±15.24,P<0.001)were significantly lower than those in the healthy control group.3.Comparison between remission period of asthma group and healthy control group:the IOS parameters R5(0.38±0.14 vs 0.35±0.07,P<0.05)?R5-R20(0.07±0.05 vs 0.04±0.03,P<0.001),?R5-R20(24.42±16.13 vs 12.03±9.45,P<0.001)and AX(0.57±0.80 vs 0.33±0.25,P<0.05)were significantly higher than the healthy group,R20(0.31±0.11±0.19 vs 0.31±0.06,P>0.05)and X5(-0.10±0.08 vs-0.1±0.05,P>0.05)were not statistically significant;PFT parameters MEF75%pre(77.31±20.31 vs 96.54±18.54,P<0.001)?MEF50%pre(77.64±27.83 vs 95.56±21.18,P<0.001)?MEF25%pre(68.35±30.69 vs 82.43±28.21,P<0.05)andMMEF75/25%pre(64.01±23.02 vs 84.37±18.79,P<0.001)were significantly lower than that of the healthy control group,and parameters FEV3/FVC%pre(99.60±7.60 vs 100.34±2.94,P>0.05)?FRC%pre(1107.57±19.57 vs 103.67±17.89,P>0.05)?IC%pre(93.80±22.36 vs 93.37±15.24,P>0.05)?RV%pre(108.07±25.8 vs 107.04± 19.03,P>0.05)?RV/TLC%pre(107.71±18.71 vs 106.69±15.04,P>0.05)?Rtot%pre(107.96±12.35 vs 99.78±27.54,P>0.05)and Reff%pre(100.45±14.24 vs 97.94±26.26,P>0.05)were not statistically significant.4.Comparison between the acute attack period and the remission period of asthma:In the asthma group,IOS parameters in the acute attack period R5(0.54± 0.25 vs 0.38±0.14,P<0.001)?R20(0.42±0.19 vs0.31±0.11,P<0.001)?R5-R20(0.12±0.08 vs 0.07±0.05,P<0.001)??R5-R20(29.69±15.06 vs 24.42±16.13,P<0.001)and AX(2.01±2.71 vs 0.57±0.80,P<0.001)were significantly higher than the remission period,and the parameter X5(-0.23±0.24 vs-0.10±0.08,P<0.001)was significantly lower than the remission period;PFT parameters RV%pre(137.80±39.25 vs 108.07±25.8,P<0.001)?RV/TLC%pre(128.83 ± 24.25 vs 107.71±18.71,P<0.001)?FRC%pre(115.14±25.45 vs 107.57±19.57,P<0.001)?Rtot%pre(173.04±80.94 vs 107.96±12.35,P<0.001)and Reff%pre(156.91±70.25 vs 100.45±14.24,P<0.001)were significantly higher than the remission period(P<0.05),Parameters FEV3/FVC%pre(98.13±5.61 vs 99.60±7.60,P<0.001)?MMEF75/25%pre(54.19±23.47 vs 64.01±23.02,P<0.001)?MEF75%pre(70.34±23.74 vs 77.31±20.31,P<0.001)?MEF50%pre(66.75±28.46 vs 77.64±27.83,P<0.001)?MEF25%pre(55.67±28.41 vs 68.35±30.69,P<0.001)and IC%pre(83.31±21.86 vs 93.80±22.36,P<0.001)were significantly lower than the remission period.5.Improvement value and improvement rate of IOS and PFT parameters in asthma remission period compared with acute attack period:The improvement rate of the following parameters AX?X5?MEF25%pre?R5-R20?Rtot%pre?MMEF75/25%pre?MEF50%pre?Reff%pre?R5?R20?MEF75%pre?IC%pre?RV%pre?RV/TLC%pre??R5-R20?FEV3/FVC%pre and FRC%pre decreased in turn.Among them,AX?X5?MEF25%pre and R5-R20 parameter improved the most significantly,Rtot%pre?MMEF75/25%pre?MEF50%pre?Reff%pre?R5?R20 and MEF75%pre also had obvious improvement,lung volume parameter IC%pre?RV%pre and RV/TLC%pre also improved to some extent,?R5-R20 improved less,FEV3/FVC%pre and FRC%pre improved the least,R20 significantly improved compared with the acute period,with improvement value significantly greater than R5-R20,and the improvement rate less than R5-R20.Conclusion:1.Compared with the healthy control group,the functions of small and large airways in the asthma group are damaged at acute stage,and the pulmonary function is improved significantly at remission stage,of which reversible airflow restriction,the degree of over inflation of the lung,and the functions of large and small airways are significantly improved,but there are still different degrees of small airway function damaged,suggesting that the recovery of small airway function is slower.2.At the acute stage of asthma,the total respiratory resistance and the central airway resistance increase,and the reversibility of the improvement of peripheral airway airflow restriction is lower than that of the central airway,suggesting that IOS can be adopted to evaluate the position and severity of airway obstruction and to evaluate early small airway dysfunction.3.Compared with PFT,IOS parameters of small airway have higher accuracy,and greater improvement rate,suggesting that IOS is more sensitive than PFT in case of detecting small airway dysfunction.Clinical symptoms of some patients are relieved,but the pulmonary function is not restored to normal level which means that further medication is necessary.IOS has an important clinical value for the diagnosis and treatment of asthma patients.4.IOS is a beneficial supplement to PFT,especially for asthma patients with early small-airway lesions,which can effectively avoid misdiagnosis or missed diagnosis,and is expected to become one of the diagnostic techniques reflecting peripheral airway inflammation and pathological status indicators.