Low Systemic Oxygen Delivery and BP and Risk of Progression of Early AKI

Abstract

Background and objectives The optimal hemodynamic management of patients with early AKI is unknown. This study aimed to investigate the association between hemodynamic parameters in early AKI and progression to severe AKI and hospital mortality.Design, setting, participants, & measurements This study retrospectively analyzed the data of all patients admitted to the adult intensive care unit in a tertiary care center between July 2007 and June 2009 and identified those with stage 1 AKI (AKI I) per the AKI Network classification. In patients in whom hemodynamic monitoring was performed within 12 hours of AKI I, hemodynamic parameters in the first 12 hours of AKI I and on the day of AKI III (if AKI III developed) or 72 hours after AKI I (if AKI III did not develop) were recorded. Risk factors for AKI III and mortality were identified using univariate and multivariate logistic regression analyses.Results Among 790 patients with AKI I, 210 (median age 70 years; 138 men) had hemodynamic monitoring within 12 hours of AKI I; 85 patients (41.5%) progressed to AKI III and 91 (43%) died in the hospital. AKI progressors had a significantly higher Sequential Organ Failure Assessment score (8.0 versus 9.6; P,0.001), lower indexed systemic oxygen delivery (DO 2 I) (median 325 versus 405 ml/min per m 2 ; P,0.001), higher central venous pressure (16 versus 13; P=0.02), and lower mean arterial blood pressure (MAP) (median 71 versus 74 mmHg; P=0.01) in the first 12 hours of AKI I compared with nonprogressors. Multivariate analysis confirmed that raised lactate, central venous pressure, and Sequential Organ Failure Assessment score as well as mechanical ventilation were independently associated with progression to AKI III; higher DO 2 I and MAP were independently associated with a lower risk of AKI III but not survival. The associations were independent of sepsis, heart disease, recent cardiac surgery, or chronic hypertension. ConclusionsHigher DO 2 I and MAP in early AKI were independently associated with a lower risk of progression.

The Golden Hours of AKI

“…This continued exploration of hemodynamic and physiologic parameters mirrors other efforts in critical care medicine, where there is a renewed focus on vital signs and other parameters to help risk stratify and prevent adverse patient outcomes (28,29). Although it is important to stress the need for prospective validation of these data, as a field we can remain hopeful that follow-up investigations will validate the findings of Raimundo et al Additional investigation may even expand the window for intervention and modification of the AKI trajectory to a period of time longer than the initial 12 golden hours reported in this study (23).…”

“…However, the broad application of such an MAP goal to all patients is not feasible, and the ideal hemodynamic strategy for the prevention of progressive AKI remains unproven. It is with this background that Raimundo et al (23) reported, in this issue of CJASN, their findings from a single-center, retrospective cohort study investigating the association between hemodynamic parameters in early AKI and AKI progression and inpatient mortality.…”

“…However, urine output and fluid balance, vasopressor use, and severity of illness scores were not associated with AKI progression in the multivariate analysis. Importantly, when Raimundo et al (23) looked at many of the hemodynamic parameters over 12-72 hours after AKI and adjusted for the initial hemodynamic measurements, the associations were no longer significant for all indices, except MAP. Not surprisingly, cumulative fluid balance, which has been previously shown to affect AKI outcomes (24,25), was associated with higher risk of AKI progression in 12-72 hours but not over the first 12 hours.…”

“…In their 790 patients in the mixed medical-surgical intensive care unit (ICU) with AKI Network Stage 1 AKI, 210 (26.6%) had hemodynamic monitoring in place within the initial 12 hours of AKI onset (23). Importantly, given the retrospective nature of this study, the decision to place hemodynamic monitoring was made at the discretion of the treating teams.…”

Relationship Between Short-Term Blood Pressure Variability and Incidence of Acute Kidney Injury in Critically Ill Patients

“…Enhanced BP variability increases variations in blood perfusion of different organs; of which, kidneys are the most susceptible because of the low renal oxygen extraction proportion (approximately 10–15%) [19]. Thus, AKI is more common in critically ill patients with enhanced BP variability, after renal function is affected by altered renal perfusion.…”