Low urine output in acute renal dysfunction (ARI/ARFS) diagnosis

Introduction

Low urine output (UO) has been recently suggested to define acute renal dysfunction/failure (ARI/ARFS) in addition to urea/creatinine levels [1]. We tested how inclusion of UO would change the incidence of ARI/ARFS in long term ICU patients.

Patients and methods

Medical records of long term ICU patients (>3 days) hospitalised in 2000 were analysed for UO during the first 8 days of ICU stay. When low UO (<200 ml/6 hours or 800 ml/24 hours minimal) was found scoring for ARI/ARFS was performed. In case creatinine was not available urea was considered sufficient for ARI/ARFS diagnosis. Furosemide medication was also recorded.

Results

Out of 189 admissions in 2000, 90 patients (62 males, 28 females), in age of 59 years (median; range 16-85 years) were hospitalised >3 days. Altogether 98 hospitalisations were analysed (eight re-admissions in seven patients). APACHE II on admission was 25.4 ± 7.7. Four patients died within the period analysed and one was discharged from the ICU. Thirty-nine ICU days when seven patients required renal replacement therapies were also excluded from the analysis. Altogether 735 ICU days were subject to analysis.

Based on decreased UO 66 ARI/ARFS days in 34 patients were recorded. Twenty five ARI/ARFS days were found in nine patients with normal urea/creatinine values (14 in a single patient). In three cases classification of ARI/ARFS including UO would lead to a more severe classification of renal dysfunction. Eight patients would have been missed if ARI/ARFS was based on urea/creatinine values only. In all but one patient where an episode with low UO was recorded no furosemide was given.

Conclusion

When diuretics are not given, inclusion of low urine output into an acute renal dysfunction definition significantly increases the number of ARI/ARFS patients.