Diuresis Effectiveness of Furosemide is Confounded by Propofol Sedation During Pediatric Renography.

Introduction: We observed an increased frequency of below-hydration post-furosemide urinary outputs (BHPFUO) during diuresis renography (DR), which can cause a false-positive obstruction diagnosis. This investigation evaluated propofol sedations’ role in causing BHPFUO.

Methods: All patients referred for Tc-99m-MAG3 DR during the last 4 months were reviewed. Per protocol, all patients’ bladders were catheterized for timed recording of the urinary output (outs). Hydration (ins) starts 15 min before imaging, using the 2018 SNMMI/EANM recommended 15 mL/kg fluid calculation (given IV), continuing to match the total ins and outs. Furosemide (F) was given (1.5 mg/kg for age <6 mo and 1.0 mg/kg for age ≥6 mo) during the F+30 DR. Post-F outs were historically always greater than the calculated/administered hydration. Those not meeting this expectation in the current study are defined as BHPFUO.

Results: There were 47 patients, 10 adults (excluded) and 37 children (included) who were ages 0.1 - 17.4 years and given 7 - 60 mg of F during the DR. Six of six children who received propofol sedation (100%) met BHPFUO criteria. The most recent of thesix (the index case) showed >20 min post-F half-time, implying obstruction. But DR without sedation 18 mo before was unobstructed and without BHPFUO. Additional imaging disputed obstruction. 13 out of 31 children studied without sedation (42%) met BHPFUO criteria, which was significantly less than in the sedation group (two-tailed p = 0.009). Additionally, 9 out of the 37 children had earlier F+30 DR (none sedated), but only one (11%) met the BHPFUO criteria.

Conclusions: There is a strong association between propofol anesthesia and BHPFUO, which raises concern for causing false positive diagnoses of obstruction. While anesthesia emerged in this review as one confounder of effective diuresis, it cannot explain all cases of BHPFUO observed in the past 4 months. Further investigations are needed to identify additional confounders in our practice and at other institutions.