Use of lung clearance index to assess the response to intravenous treatment in cystic fibrosis

Abstract

Background: Progressive lung disease is the main cause of clinical deterioration and mortality in cystic fibrosis (CF) patients. Being able to assess the effectiveness of interventions is very significant.

Objectives: To assess the response to intravenous (IV) treatment among CF patients, using forced expired volume in 1(st) second (FEV1) and Lung Clearance Index (LCI) as outcome measures and to compare the effect of IV treatment on lung function and LCI between CF children being treated on a regular basis, or in case of a pulmonary exacerbation.

Subjects and methods: Thirty-two CF patients (15 males) with mean age 9.90 (range: 2-23) years, performed spirometry and multiple breath washout (MBW) before and one month after IV antibiotic treatment. Nineteen patients received a course of elective treatment (group A) and 13 received IV antibiotic regimens for an acute exacerbation (group B).

Results: Statistically significant differences after treatment were seen in LCI (p≤0.001), and Forced Expiratory Flow (FEF) z-scores (p<0.05). FEV1 did not change significantly after drug intervention. Dividing patients into two groups, only LCI showed significant change (p<0.05), when treatment was administered on a regular basis. Patients being treated for an acute pulmonary exacerbation showed significant improvement in most of the lung function parameters: LCI (p=0.0001), FEV1% (p=0.05), FEV1 z-score (p=0.033) and FEF25-75 (p=0.046). The mean LCI difference was significantly greater in group B compared to group A (p=0.001).

Conclusion: LCI is more sensitive marker than FEV1 to assess the effect of IV antibiotic treatment among CF children. IV antibiotics are more effective on lung function parameters, when they are administered for an acute exacerbation, than when they are given on a regular basis. Hippokratia 2015, 19 (1): 47-52.

Keywords: cystic fibrosis; evaluation of intervention; intravenous treatment; lung clearance index; pulmonary exacerbation.

Figure 1. Pre and post IV treatment lung clearance index (LCI) for study’s participants divided into two groups; Group A (patients being treated on a regular basis) and Group B (patients being treated for an acute exacerbation)

Figure 2. Correlation between the change in lung clearance index (LCI) and the change in forced expired volume in 1st second % predicted (FEV₁%) among patients being treated either on a regular basis (black circle) or in case of an acute pulmonary exacerbation (white circle ).