The clinical relevance of oliguria in the critically ill patient: analysis of a large observational database

Crit Care. 2020 Apr 23;24(1):171. doi: 10.1186/s13054-020-02858-x.

Abstract

Background: Urine output is widely used as one of the criteria for the diagnosis and staging of acute renal failure, but few studies have specifically assessed the role of oliguria as a marker of acute renal failure or outcomes in general intensive care unit (ICU) patients. Using a large multinational database, we therefore evaluated the occurrence of oliguria (defined as a urine output < 0.5 ml/kg/h) in acutely ill patients and its association with the need for renal replacement therapy (RRT) and outcome.

Methods: International observational study. All adult (> 16 years) patients in the ICON audit who had a urine output measurement on the day of admission were included. To investigate the association between oliguria and mortality, we used a multilevel analysis.

Results: Of the 8292 patients included, 2050 (24.7%) were oliguric during the first 24 h of admission. Patients with oliguria on admission who had at least one additional 24-h urine output recorded during their ICU stay (n = 1349) were divided into three groups: transient-oliguria resolved within 48 h after the admission day (n = 390 [28.9%]), prolonged-oliguria resolved > 48 h after the admission day (n = 141 [10.5%]), and permanent-oliguria persisting for the whole ICU stay or again present at the end of the ICU stay (n = 818 [60.6%]). ICU and hospital mortality rates were higher in patients with oliguria than in those without, except for patients with transient oliguria who had significantly lower mortality rates than non-oliguric patients. In multilevel analysis, the need for RRT was associated with a significantly higher risk of death (OR = 1.51 [95% CI 1.19-1.91], p = 0.001), but the presence of oliguria on admission was not (OR = 1.14 [95% CI 0.97-1.34], p = 0.103).

Conclusions: Oliguria is common in ICU patients and may have a relatively benign nature if only transient. The duration of oliguria and need for RRT are associated with worse outcome.

Keywords: Mortality; Renal replacement therapy; Urine output.

Publication types

  • Observational Study

MeSH terms

  • Acute Kidney Injury / prevention & control
  • Acute Kidney Injury / therapy
  • Adult
  • Aged
  • Aged, 80 and over
  • Analysis of Variance
  • Critical Illness / epidemiology
  • Critical Illness / mortality
  • Critical Illness / therapy*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Mortality*
  • Oliguria / etiology*
  • Oliguria / mortality*
  • Prospective Studies
  • Renal Replacement Therapy / methods*
  • Renal Replacement Therapy / trends
  • Statistics, Nonparametric