Normalized residual activity and output efficiency in case of early furosemide injection in children

Values for output efficiency (OE) and normalized residual activity (NORA) in paediatric patients have been published previously. However, it is now a usual practice to inject furosemide at the beginning of a renogram acquisition (F0 procedure). The aim was to evaluate OE and NORA obtained on F0 renograms, in normal and abnormal paediatric kidneys.

Three groups of kidneys were selected: group 1, normal kidneys (n=155); group 2, dilated but unobstructed kidneys (n=20); and group 3, hydronephrotic kidneys (n=84). A 20-min Tc-mercaptoacetyltriglycine renogram was obtained under early furosemide injection (F0) and was completed by late postmicturition (PM) images. OE and NORA were calculated at the end of the renogram and on the PM images.

Group 1: NORA and OE calculated at the end of the F0 renogram revealed better drainage than without F0 stimulation. The PM parameters were comparable with those previously obtained after late furosemide injection (F+20). Group 2: the drainage, despite the early injection of furosemide, was often unsatisfactory at the end of the F0 renogram, but improved dramatically upon the PM acquisition. Group 3: almost normal values up to very abnormal ones were observed. In 35% of kidneys, the values of drainage were out of the range of group 2.

Under early furosemide injection, renal drainage in the normal kidneys was better than in basic conditions. In dilated unobstructed kidneys, NORA and OE obtained on late images after micturition were, respectively, below 1.5 and above 80%.