Intensive Monitoring of Urine Output Is Associated With Increased Detection of Acute Kidney Injury and Improved Outcomes

Chest. 2017 Nov;152(5):972-979. doi: 10.1016/j.chest.2017.05.011. Epub 2017 May 17.


Background: Urine output (UO) is a vital sign for critically ill patients, but standards for monitoring and reporting vary widely between ICUs. Careful monitoring of UO could lead to earlier recognition of acute kidney injury (AKI) and better fluid management. We sought to determine if the intensity of UO monitoring is associated with outcomes in patients with and those without AKI.

Methods: This was a retrospective cohort study including 15,724 adults admitted to ICUs from 2000 to 2008. Intensive UO monitoring was defined as hourly recordings and no gaps > 3 hours for the first 48 hours after ICU admission.

Results: Intensive monitoring for UO was conducted in 4,049 patients (26%), and we found significantly higher rates of AKI (OR, 1.22; P < .001) in these patients. After adjustment for age and severity of illness, intensive UO monitoring was associated with improved survival but only among patients experiencing AKI. With or without AKI, patients with intensive monitoring also had less cumulative fluid volume (2.98 L vs 3.78 L; P < .001) and less fluid overload (2.49% vs 5.68%; P < .001) over the first 72 hours of ICU stay.

Conclusions: In this large ICU population, intensive monitoring of UO was associated with improved detection of AKI and reduced 30-day mortality in patients experiencing AKI, as well as less fluid overload for all patients. Our results should help inform clinical decisions and ICU policy about frequency of monitoring of UO, especially for patients at high risk of AKI or fluid overload, or both.

Keywords: acute renal failure; critical illness; fluid overload; mortality; serum creatinine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Kidney Injury / diagnosis*
  • Acute Kidney Injury / physiopathology
  • Adult
  • Aged
  • Disease Progression
  • Female
  • Follow-Up Studies
  • Humans
  • Intensive Care Units*
  • Male
  • Middle Aged
  • Monitoring, Physiologic / methods*
  • Predictive Value of Tests
  • Retrospective Studies
  • Time Factors
  • Urination / physiology*