| Background: Bronchial Provocation Test(BPT)performed by the forced oscillation method is a new measurement of airway responsiveness by an astograph,Jupitor 21(Chest,Tokyo,Japan).Briefly,respiratory resistance(Rrs)is measured by the forced oscillation technique(FOT)during continuous inhalation of methacholine in stepwise incremental concentrations.The forced oscillation method,indicating both airway reactivity and sensitivity,is considered as a useful tool for studying asthma.However,comparison of bronchial provocation tests measured by the standardized dosimeter method and the forced oscillation method is lacking.The application value of the forced oscillation method in the clinical practice is not yet known.Standardizations are required for evaluation criteria of the forced oscillation method.Consequently,the aims of the study are to compare diagnostic value and safety of BPTs measured by the dosimeter method and the forced oscillation method in patients with bronchial asthma,assess the clinical application of the forced oscillation method in the diagnosis and evaluation of asthma.Method: This was a single-center cross-over prospective clinical study.Airway responsiveness was measured by the dosimeter method and the forced oscillation method in asthmaticpatients and healthy subjects,who were recruited from the First Affiliated Hospital of Guangzhou Medical University.Two tests were performed according to a randomized number sequence.The between-test interval was 24 hours.Data was collected for analysis.Comparisons of parameters between two groups were using t-test or Wilcoxon test.Comparisons among three or more groups were using One-way ANOVA or Kruskal-Wallis test.ROC curves analysis were performed to assess the diagnostic value of parameters.Adverse events were recorded and analyzed.A p value of less than 0.05 was recognized as significant.Results: 1.Of 191 adults who underwent screening procedures,183 subjects,including 107 asthmatic patients and 76 healthy subjects,met the inclusion criteria.A total of 27 patients with uncontrolled,34 with partly controlled,and 32 with controlled asthma,as well as 69 healthy control subjects,who finished two tests were included in the final analysis.2.Major spirometric parameters in asthmatic patients were lower considerably than those in healthy subjects(p<0.01),with the exception of FVC(F=1.579,p=0.197)and FVC%Pred(F=0.609,p=0.610).FEF25%-75%%Pred,FEF50%%Pred and FEF75%%Pred were similar between patients with uncontrolled and partly controlled asthma and lower than those in patients with controlled asthma(p<0.05).3.All parameters measured by the forced oscillation method differed considerably between asthmatic patients and healthy subjects(All p<0.01).Dmin value in asthmatic patients was lower and SGrs,Rrs were higher,compared with healthy subjects.Dmin value in patients with uncontrolled asthma was lower than that in patients with controlled asthma(p<0.05).PD20-FEV1 in patients with uncontrolled and partly controlled asthma were lower than that in patients with controlled asthma(p<0.05).4.Relationship between spirometric and BPTs parameters was analysed in all subjects.Log PD20-FEV1 and Log Dmin were positively related to FEF25%-75%%Pred,FEF50%%Pred,FEF75%%Pred(p<0.01).The correlation coefficient betweenLog PD20-FEV1 and FEF25%-75%%Pred was highest(r=0.6114),followed by that between Log Dmin and FEF25%-75%%Pred(r=0.5935).Log PD20-FEV1,Log Dmin were positively related to FEV1/FVC(r=0.5552,0.5563,p<0.01).Log PD20-FEV1 was positively correlated with Log Dmin,Log PD40,Log PD35(r=0.8111,0.8046,0.7971,p<0.01).SGrs was unrelated to any spirometric parameters.Log Dmin was not related to SGrs.5.ROC curves revealed slightly superior screening capability of the dosimeter method(AUC,0.981;95%CI,0.952-1.000)over the forced oscillation method(AUC,0.959;95%CI,0.924-0.994).The positive rate between two tests showed no difference(x2=1.043,p>0.05).The sensitivity,specificity,positive predictive value(PPV),negative predictive value(NPV),accuracy,Youden,s index of BPT measured by the dosimeter method were 98.9%,98.6%,98.9%,98.6%,98.8%,0.98.Those of BPT measured by the forced oscillation method were 100%,87.0%,91.2%,100%,94.4%,0.87,respectively.6.The major adverse events of two tests were tightness,tachypnea,coughing,wheezing,dyspnea,palpitation.The incidence rate of adverse events by the dosimeter method(62.3%)was lower than that by the forced oscillation method(72.8%)(p<0.05).The incidence rate of adverse events in patients with uncontrolled asthma was greater than that in patients with partly controlled asthma,followed by that in patients with controlled asthma in both tests(p<0.05).Furthermore,the incidence rate of tightness,tachypnea,coughing and wheezing differed considerably(p<0.01),that of itching and dizziness was similar in asthmatic patients with different levels of control status.7.Most of subjects(51.2%)were recovered within 10 minutes after inhalation of 200 to 400 ?g of salbutamol administered through a metered-dose inhaler by the dosimeter method.Most of subjects(58.0%)were recovered within 10 minutes after continuous inhalation of 1 to 2 minutes of salbutamol solution administered through mouthpiece by the forced oscillation method.It took 9 minutes(range,8~11 minutes)by the forced oscillation method and 25 minutes(range,22~30 minutes)by the dosimeter method during testing in asthmatic patients(p<0.01).It took 12 minutes(range,12~13 minutes)by the forced oscillation method and 20 minutes(range,19~22 minutes)by the dosimeter method during testing in healthy subjects(p<0.01).Both tests were well tolerated.No serious adverse event was foundConclusions: The diagnostic value of the dosimeter method was slightly higher than the forced oscillation method,which was valuable in the diagnosis of asthma.The forced oscillation method was simple,safe,time-saving and worthy of clinical application. |
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