Predictors of acute kidney injury in patients undergoing adult cardiac surgery

Association of urine output during cardiopulmonary bypass and postoperative acute kidney injury in patients undergoing coronary artery bypass graft

Acute kidney injury (AKI) is a common complication in patients undergoing coronary artery bypass graft (CABG) surgery and is associated with significant morbidity and mortality. We investigated the association of urine output (U/O) during cardiopulmonary bypass (CPB) with postoperative AKI in a cohort of patients undergoing elective CABG.

This single-center retrospective study used data from patients undergoing elective CABG with CPB (March 2015 to March 2020). Demographic data and perioperative information were extracted from the Patients' records. Urine output during CPB and in the first 3 days after surgery was also recorded. Acute kidney injury was defined according to the Acute Kidney Injury Network (AKIN) classification. Spearman's correlation analysis was used to evaluate the relationship between quantitative variables and multiple logistic regression analysis was applied to determine AKI predictors.

A total of 532 patients with a mean age of 56.83 ± 7.99 years were analyzed. In the first 48 h after surgery, the incidence of AKI was 18%, of which, 7 (2.7%) patients developed stage II of AKI. There was no significant correlation between U/O during CPB and change in postoperative blood urea nitrogen (BUN) and creatinine. Oliguria during CPB was not observed in any of the patients. Age and duration of bypass were identified as predictors of AKI.

In this study, the incidence of AKI was 18% and there was no significant correlation between U/O during CPB and changes in postoperative BUN and creatinine. Age and duration of bypass were independent risk factors of AKI.

Cardiac Surgery-associated Acute Kidney Injury in Patients with Preserved Baseline Renal Function

INTRODUCTION

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a powerful predictor of perioperative outcomes. We evaluated the burden of CSA-AKI in patients with preserved baseline renal function.

METHODS

The data of 2,162 adult patients who underwent cardiac surgery from January 2005 to December 2020 were analyzed. Logistic regression models were used to determine predictors of CSA-AKI and their associations with hospital mortality up to 30 days.

RESULTS

The prevalence of acute kidney injury was 43.0%, and 2.0% of patients required renal replacement therapy. Hospital mortality rate was 5.6% (non-acute kidney injury = 2.0% vs. CSA-AKI = 10.4%, P<0.001), and any degree of CSA-AKI was associated with a significant increase in death rates (stage 1 = 4.3%, stage 2 = 23.9%, stage 3 = 59.7%). Multivariable logistic regression analysis identified age, obesity, left ventricular dysfunction, previous cardiac surgery, and cardiopulmonary bypass duration as predictors of CSA-AKI. Moreover, CSA-AKI was confirmed as independent predictor of hospital mortality for stage 1 (odds ratio, 2.02; 95% confidence interval, 1.16 to 3.51; P=0.013), stage 2 (odds ratio, 9.18; 95% confidence interval, 4.54 to 18.58; P<0.001), and stage 3 (odds ratio, 37.72; 95% confidence interval, 18.87 to 75.40; P<0.001) patients.

CONCLUSION

Age, obesity, left ventricular dysfunction, previous cardiac surgery, and cardiopulmonary bypass duration are independent predictors of CSA-AKI in patients with preserved baseline renal function. The development of CSA-AKI is significantly associated with worse outcomes, and there is a dose-response relationship between acute kidney injury stages and hospital mortality.

Hyperchloremia and Postoperative Acute Kidney Injury in Adult Cardiac Patients: A Propensity-Matched Cohort Study

OBJECTIVES

Hyperchloremia is a potential risk factor for acute kidney injury (AKI) in critically ill patients. However, the relationship between hyperchloremia and postoperative AKI in adult patients undergoing cardiovascular surgery with cardiopulmonary bypass (CPB) remains unclear. The authors aimed to determine whether postoperative hyperchloremia was associated with postoperative AKI in these populations.

OBJECTIVES

Retrospective, single-center study.

SETTING

Tertiary care hospital.

PARTICIPANTS

Adult patients who underwent cardiovascular surgery with CPB.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients with and without postoperative hyperchloremia were matched (1:1). The primary outcome was the rate of postoperative AKI diagnosed using the Kidney Disease: Improving Global Outcomes consensus criteria. Postoperative hyperchloremia was defined as postoperative serum chloride levels of >110 mmol/L during the first 48 hours. An increase in serum chloride levels (Δ[Cl^-]) was defined as the difference between the preoperative and maximum postoperative serum chloride levels during the first 48 hours ([Cl^-]_max). Propensity-score matching and univariate and multivariate logistic regression analyses were employed. A total of 323 patients were included. Propensity-score matching selected 55 pairs for the final comparison. The incidence of postoperative AKI did not differ between the two groups (47% v 46%, p = 1.0). In the multivariate logistic regression analysis, Δ[Cl^-] was associated independently with the development of postoperative AKI (odds ratio, 1.13; 95% confidence interval, 1.06-1.21; p < 0.001).

CONCLUSIONS

Exposure to postoperative hyperchloremia was not associated with postoperative AKI in adult patients undergoing cardiovascular surgery with CPB. However, an increase in the serum chloride level might be associated with postoperative AKI.

Prognostic Utility of KDIGO Urine Output Criteria After Cardiac Surgery

OBJECTIVES

Kidney Disease: Improving Global Outcomes (KDIGO) guidelines include assessment of creatinine and urine output to identify acute kidney injury (AKI). Whether urine output is an accurate indicator of AKI after cardiac surgery, however, is unclear. The authors' goal was to examine whether cardiac surgery patients who fulfilled criteria for AKI by KDIGO urine output criteria also demonstrated kidney injury by elevated creatinine, other kidney biomarkers, or had worse clinical outcomes.

DESIGN

Secondary analysis of prospectively collected data from a clinical trial, "6% Hydroxyethyl starch 130/0.4 in Cardiac Surgery (NCT02192502)."

SETTING

Academic, quaternary care hospital.

PARTICIPANTS

Patients undergoing elective aortic valve replacement INTERVENTIONS: None MEASUREMENTS AND MAIN RESULTS: One hundred forty-one patients were classified into AKI stage by KDIGO urine output criteria within 24 hours after surgery. Kidney biomarkers (serum creatinine, urinary neutrophil gelatinase-associated lipocalin [NGAL], urinary interleukin-18 [IL-18]) and hospital and intensive care unit length of stay were analyzed across AKI stages. Urine output criteria classified four times as many patients with AKI than creatinine criteria (95 [67%] v 21 [15%]). Most patients meeting KDIGO urine output criteria for AKI postoperatively did not satisfy KDIGO creatinine criteria for AKI within one week (77 of 95 [81%]) or six-to-12 months (27 of 29 [93%]). Higher AKI stage assessed by urine output was not associated with higher NGAL, IL-18, or longer hospital or intensive care unit stays.

CONCLUSIONS

Acute kidney injury classified by KDIGO urine output criteria was not associated with other biomarkers of kidney injury or worse patient outcomes. These data suggested that KDIGO urine output criteria after cardiac surgery may overclassify AKI stage; further research is needed.

Mild AKI is associated with mortality of patients who underwent cardiopulmonary bypass surgery

Acute kidney injury (AKI) stage I is the most common stage of AKI observed among patients who underwent cardiac surgery with cardiopulmonary bypass (CPB). The relationship between AKI stage I and mortality requires further investigation. Patients aged 18 years or older who underwent cardiac surgery with CPB between July 1, 2013 and May 31, 2014, were reviewed in the present study. Patients were dichotomized into: i) The AKI stage I group, and ii) the non-AKI group. The primary measured characteristic in the present study was the relationship between AKI and mortality. Kaplan-Meier survival analyses were taken to obtain survival curves. A total of 1,846 patients were included in this present study. The mean age was 51.76±13.56 years. A total of 1,508 patients did not develop AKI and 338 developed AKI stage I. The mean follow-up period among survivors was 9.95±3.45 months. Kaplan-Meier survival analyses showed that patients with AKI stage I were at an increased mortality risk (P<0.0001). In multivariate Cox regression analysis, AKI stage I remained independently associated with a reduced survival. Using a subgroup analysis, patients with non-recovery AKI (defined as non-recovery AKI if the serum level does not return before surgery) had a higher mortality rate than patients with recovery AKI (P<0.0001). AKI stage I is the most common form of AKI and it is independently related to all-cause mortality in patients who underwent cardiovascular surgery with cardiopulmonary bypass.