The Proportion of Lung Hyperinflation In Patients With Persistent Asthma In Persahabatan Hospital Jakarta Using Multiple Breath N2-Washout

Background: In asthma, small airway dysfunction and inflammation may induce significant lung hyperinflation. The aim of the study is to discover the proportion of lung hyperinflation in patient with persistent asthma in Persahabatan Hospital Jakarta. Method: A cross sectional study with descriptive analysis was done in Asthma clinic Persahabatan Hospital from September-November 2016. Forty-five subjects were recruited consecutively. Interview, physical examination, chest x-ray (CXR), spirometry and multiple
breath N2-washout (MBW) were performed. Lung hyperinflation was defined as a residual volume /total lung capacity (RV/TLC%) above the upper limit of normal. Results: The proportion of lung hyperinflation in patients with persistent asthma was 17,8% (8 of 45 subjects). Median RV in milliliter was 1230 (570-2860). Median functional residual capacity (FRC) in milliliter was 1730 (970-3990). Median TLC in milliliter was 3310 (2490-6350). Mean RV/TLC ratio was 36.39% (SD±8.86). Mean FRC/TLC ratio was 52.86%
(SD±6.85). There was a significant correlation between forced expiratory volume in 1 second (FEV1%) value with lung hyperinflation with the decline of FEV1 <60% increased the risk of lung hyperinflation by 8,46 (95%CI=1.155-61.98; P=0.036). There were no significant correlation between age, gender, smoking habit, body mass index (BMI), ACT score, the severity of persistent asthma, duration of asthma, duration of steroid inhalation use, exacerbation history in the last 12-months and emphysematous in CXR with lung hyperinflation (P>0.05). Conclusion: The proportion of lung hyperinflation in patient with persistent asthma in Persahabatan Hospital Jakarta is 17,8%. Lung hyperinflation in persistent asthma is associated with the degree of airway obstruction.