Influence of inhaled steroids on pulmonary epithelial permeability to Tc99m-dTPA in atopic asthmatic children.

The lung permeability of asthmatic children has been reported to be similar, lower, or higher than that of healthy subjects. The aim of this study was to clarify these discrepancies and also assess the effect of inhaled steroids on lung permeability. Tc99m-diethylenetriaminepentaaceticacid (Tc99m-DTPA) clearance in children with mild unstable asthma (n = 13; mean age 9.3 +/- 0.7 years) was compared with that of a group of healthy subjects (n = 11; mean age 8.9 +/- 0.8 years). Symptom scores, forced-expiratory volume in the first second (FEV1), and peak expiratory flow rate variability (PEFR-v) of asthmatics were recorded and an inhaled steroid (budesonid) was recommended after first scintigraphic evaluation for 8 weeks. Two consecutive scintigraphic studies were performed before and after treatment. Symptoms, FEV1, and PEFR-v significantly improved throughout the study. Baseline DTPA clearance rate in the asthmatics was significantly higher from that of control group (1.3 +/- 0.2 and 0.7 +/- 0.1%/min, respectively) (p < 0.05). DTPA clearance rate of asthmatics significantly increased to 1.7 +/- 0.3%/min at end of inhaled therapy (p < 0.05). Our data show that DTPA clearance in unstable asthmatic children is significantly higher than that found in healthy subjects, and that a higher rate was obtained following inhaled steroid therapy. Thus, the clinical significance of these observations needs further studies to test whether DTPA clearance index is a valid tool for monitoring asthmatic children and to explore the mechanisms involved in radioaerosol clearance rates in pediatric asthma.