Urine Output and Mortality in Patients Resuscitated from Out of Hospital Cardiac Arrest

Abstract

Background: Limited data exist regarding urine output (UO) as a prognostic marker in out-of-hospital-cardiac-arrest (OHCA) survivors undergoing targeted temperature management (TTM).

Methods: We included 247 comatose adult patients who underwent TTM after OHCA between 2007 and 2017, excluding patients with end-stage renal disease. Three groups were defined based on mean hourly UO during the first 24 hours: Group 1 (<0.5 ml/kg/hr, n=73), Group 2 (0.5-1 ml/kg/hr, n=81) and Group 3 (>1 ml/kg/hr, n=93). Serum creatinine was used to classify acute kidney injury (AKI). The primary and secondary outcomes respectively were in-hospital mortality and favorable neurological outcome at hospital discharge (modified Rankin Scale [mRS]<3).

Results: In-hospital mortality decreased incrementally as UO increased (adjusted OR 0.9 per 0.1 ml/kg/hr higher; p=0.002).  UO<0.5 ml/kg/hr was strongly associated with higher in-hospital mortality (adjusted OR 4.2 [1.6-10.8], p=0.003) and less favorable neurological outcomes (adjusted OR 0.4 [0.2-0.8], p=0.007). Even among patients without AKI, lower UO portended higher mortality (40% vs. 15% vs. 9% for UO groups 1, 2, and 3 respectively, p<0.001).

Conclusion: Higher UO is incrementally associated with lower in-hospital mortality and better neurological outcomes. Oliguria may be a more sensitive early prognostic marker than creatinine-based AKI after OHCA.

Note:
Funding Information: No extramural source of funding was involved in this research.

Conflict of Interests: None.

Ethical Approval: The Institutional Review Board of Mayo Clinic approved this retrospective cohort study as minimal risk to patients (#15-007334). It was performed under a waiver of informed consent for patients who have provided Minnesota Research Authorization.

Keywords: Out-of-hospital-cardiac-arrest, Post Cardiac Arrest Care, Acute Kidney Injury, Urine Output, Shock, Prognostication