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

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.

Association of Oliguria With Acute Kidney Injury Diagnosis, Severity Assessment, and Mortality Among Patients With Critical Illness

“…These discrepancies with our study could be explained by (1) nonstandardized UO assessment and different management of missing values, (2) distinct populations with a higher prevalence of medical patients and respiratory issues, and (3) differences in fluid management leading to different incidence of AKI. 9 Nevertheless, on multivariate analyses, UO criteria were also found to be an independent risk factor for 90-day mortality (OR, 2.89; 95% CI, 1.96-4.25; P < .001).…”

“… 4 Most studies reporting AKI outcomes have solely relied on sCr criteria or have applied modified/simplified UO criteria. 2 , 5 , 6 , 7 , 8 , 9 Indeed, sCr levels are regularly monitored in hospitalized patients and can easily be retrieved through electronic medical records. Hence, sCr-based staging is straightforward and can even trigger bedside e-alerts.…”

COVID‐19 patients in intensive care develop predominantly oliguric acute kidney injury

“…In patients with oliguria classified as AKI stage 2, isolated oliguria was common and lower levels of U‐Cystatin C and NGAL were found. Although little is known about the clinical relevance of oliguric renal failure in COVID‐19, several studies have investigated oliguria in the ICU and found that both duration and severity of oliguria is associated with increased risk of end‐stage renal disease and death 16‐18 but not in parity with the Creatinine criteria 19 . This strengthen the notion that these pathways also benefit exploration individually.…”

A deep-learning model to continuously predict severe acute kidney injury based on urine output changes in critically ill patients

“…When urine output is considered, whether or not it is associated with an increase in serum creatinine, a higher number of AKI cases are diagnosed, and the detection can be made earlier [ 19 ]. The duration of oliguria appears to be associated with the beginning of dialysis and an increased risk of death [ 23 ]. The definition of oliguria has recently received critical appraisal: the impact of both the volume of urine as well as the duration of oliguria on AKI prediction is controversial: KDIGO Clinical Practice Guidelines for Acute Kidney Injury [ 24 ] define a urine output < 0.5 ml/kg/h for > 6 h as AKI stage 1, < 0.5 ml/kg/h for > 12 h as AKI stage 2, and a < 0.3 ml/kg/h for 24 h or anuria for 12 h as AKI stage 3.…”