Clinical usefulness of Electrical Impedance Tomography (EIT) in the evaluation of obese asthmatic children’ ventilation: a pilot case-control study

Abstract

Background: Many studies described a peculiar phenotype of “obesity with asthma”, characterized by increased asthma severity and reduced response to asthma medications. EIT is a noninvasive imaging method for visualizing the distribution of lung ventilation. In this case-control pilot study, we aim to asses the clinical usefulness of EIT in monitoring the ventilation distribution and bronchodilators responsiveness in obese children with asthma (cwA).

Methods: Obese cwA and age- and sex-matched normal-weight cwA underwent EIT test and, subsequently, spirometry. After bronchodilator (BD) administration, the two tests were repeated.

Results: We included 11 obese and normal-weight cwA aged 12.6 (2.6) yrs. No evidence of difference between groups was found in terms of global inhomogeneity index (GI_tot) after BD: 0.3 (-3.4; 2.8)% in obese cwA and -0.5 (-3.3; 2.2) % in normal-weight cwA (P=0.891). Response to BD did not differ between groups: 5.3 (-9.6; 20.2) pre-postFEV₁ in obese cwA and 5.9 (-2.3; 14.0) pre-postFEV₁ in normal-weight cwA (P=0.946). Abdominal circumference in obese cwA was strongly correlated with pre-postFEV1 response to BD (rho=0.64) and showed a negative correlation with response to BD in terms of regional ventilation delay (RVD40) (rho=-0.15), suggesting larger response to BD in those with greater waist circumference.

Conclusion: Obese and normal-weight cwA seem to show a similar response to BD; greater abdominal circumference seems to be associated to a larger response to BD, as documented by EIT. Using EIT in the clinic could be a useful to revealing unknown details about the dynamics of ventilation in obese cwA.