Oliguria on the Day of Intubation Is Associated With Mortality in Patients With Acute Respiratory Distress Syndrome

Abstract

OBJECTIVES:To investigate the relationship between oliguric acute kidney injury (AKI) and mortality in patients with acute respiratory distress syndrome (ARDS). DESIGN: Retrospective cohort study.SETTING: This investigation took place at a single-center, tertiary referral multidisciplinary comprehensive healthcare hospital in metropolitan Detroit, Michigan. PATIENTS:Adult patients 18 years old or older hospitalized in the ICU and diagnosed with ARDS on mechanical ventilation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS:Three hundred eight patients were included in the final analysis. Risk factors associated with mortality included advanced age (p < 0.001), increased body mass index (p = 0.008), and a history of chronic kidney disease (p = 0.023). Presence of AKI by day 1 of intubation, with elevated creatinine (p = 0.003) and oliguria (p < 0.001), was significantly associated with mortality. On multivariate analysis, advanced age (relative risk [RR], 1.02), urine output on the day of intubation (RR, 0.388), bicarbonate level (RR, 0.948), and Sequential Organ Failure Assessment severity score (RR, 1.09) were independently associated with mortality. A receiver operating characteristic curve identified a threshold urine output on the day of intubation of 0.7 mL/kg/hr (area under the curve, 0.75; p < 0.001) as most closely associated with inpatient mortality (i.e., urine output < 0.7 mL/kg/hr is associated with mortality). CONCLUSIONS:For patients with ARDS, oliguria on the day of intubation was independently associated with increased mortality. Urine output of less than 0.7 mL/kg/hr predicted 80% of inpatient deaths. These findings herald an augmented understanding of the role of urine output in medical decision-making and prognostication.

Tocilizumab Associated With Survival in Patients Hospitalized for COVID-19 Acute Respiratory Distress Syndrome and Low Urine Output

“…Interestingly, similar to a previous investigation at our institution, we reported a strong association between low urine output on the day of intubation and mortality in this group of patients with moderate-severe ARDS. 4 This finding is an important one, as the threshold for low urine output in our study is slightly higher than the traditional cutoff for oliguria of 0.5 mL/kg/h. Recognizing that patients with low urine output, despite not yet having met formal criteria for AKI by oliguria, may still have progressive ongoing renal injury that ultimately plays a role in the complex pathophysiology of ARDS, resulting in a higher mortality rate.…”

“…On this note, approximately 92% of the patients with low urine output by our threshold did ultimately meet criteria for AKI on the day of intubation, which further suggests that monitoring dynamic changes in urine output can help guide clinical decision making in such patients. 3,4 Additionally, although those receiving tocilizumab were predominantly Black, a larger proportion of Black patients included in the study were not treated with tocilizumab, while the proportion of White patients was reversed. The reason for this difference is unclear and should warrant consideration of healthcare disparities in Blacks, resulting from healthcare provider bias and/or a cultural apprehension to receive therapies with novel indications in the context of notorious historical race-based medical studies.…”

“…On this note, approximately 92% of the patients with low urine output by our threshold did ultimately meet criteria for AKI on the day of intubation, which further suggests that monitoring dynamic changes in urine output can help guide clinical decision making in such patients. 3,4…”

“…In our study, the urine output on the day of intubation was used to determine presence of oliguria, alternatively defined as a urine output of ≤ 0.7 mL/kg/h, consistent with our previous study. 4 Baseline serum creatinine was defined as the last serum creatinine value preceding the index hospitalization. 15% of patients did not have a baseline serum creatinine prior to hospitalization, and in such cases the urine output was used to define AKI.…”

“…Acute respiratory distress syndrome (ARDS) in combination with acute kidney injury (AKI) is associated with increased mortality upwards of 80%, [1][2][3] and presence of oliguria at a threshold of 0.7 milliliters of urine per body weight in kilograms per hour (mL/kg/h) has been independently associated with mortality in prior reports. 4 Such associations between ARDS and AKI have been analyzed most recently in the context of Coronavirus Disease 2019 (COVID- 19), which has demonstrated a higher incidence of AKI and increased mortality in critically ill patients. 5,6 With infectious pneumonia recognized as the most common cause of ARDS, 7 COVID-19 resulted in an overwhelming majority of ARDS cases during the pandemic and was associated with high overall mortality in the critically ill population.…”