Indirect evaluation of lung condition by means of LF-NMR following chest physiotherapy or ETI administration in cystic-fibrosis patients

Abstract

Background

As most cystic fibrosis (CF) patients progress to respiratory failure, lung functionality assessment is pivotal. We previously developed a test that monitors airways measuring the spin-spin relaxation time (T_2m) of water hydrogens present in sputum using Low Field-Nuclear Magnetic resonance (LF-NMR).

Objectives

To investigate further the significance of T_2m exploring: 1) T_2m correlation with the effects of chest physiotherapy (CP); 2) the influence of sputum contamination by saliva on T_2m; 3) T_2m relation with sputum mesh size; 4) T_2m correlation with the effects of the CFTR-modulator Elexa-caftor/Tezacaftor/Ivacaftor (ETI).

Methods

T_2m was measured in the sputum of 16 CF-patients before/after CP and in 9/16 patients before/after ETI administration. FEV₁/C reactive protein (CRP)/erythrocyte-sedimentation rate (ESR) and sweat chloride concentration were measured using standard techniques. Sputum contamination by saliva/sputum mesh size were determined mathematically.

Results

We prove that T_2m can be used to detect the lack of significant effects on lung function by CP (confirmed by FEV₁). Moreover, we developed of a mathematical approach to correct T_2m value in sputum samples contaminated by saliva and to determine the relationship between T_2m and sputum mesh size. Finally, we show that T_2m can effectively detect the positive effects of ETI on lung function (evaluated by FEV₁) and that T_2m inversely correlates with the CRP/ESR/chloride sweat concentration.

Conclusion

This data strengthens the rationale for T_2m employment in CF lung disease monitoring and show that T_2m can be profitably used to complement the FEV₁ test.