Early Postoperative Acetaminophen Administration and Severe Acute Kidney Injury After Cardiac Surgery.

RATIONALE & OBJECTIVE: Oxidative stress may contribute to the development of acute kidney injury (AKI) after cardiac surgery. Acetaminophen can be considered an antioxidant because it inhibits hemoprotein-catalyzed lipid peroxidation. We hypothesized that perioperative acetaminophen administration is associated with reduced AKI after cardiac surgery. STUDY DESIGN: Retrospective observational cohort study. SETTING & PARTICIPANTS: Patients aged≥18 years who had cardiac surgery were identified from 2 publicly available clinical registries: the Medical Information Mart for Intensive Care III (MIMIC-III) and the eICU Collaborative Research Database (eICU). EXPOSURE: Administration of acetaminophen in the first 48 hours after surgery. OUTCOME: Severe AKI in the first 7 days after surgery, defined as stage 2 or stage 3 AKI according to KDIGO criteria. ANALYTICAL APPROACH: Multivariable cause-specific hazards regression analysis. RESULTS: We identified 5,791 patients from the MIMIC-III and 3,840 patients from the eICU registries. The overall incidence of severe AKI was 58% (3,390 patients) in the MIMIC-III cohort and 37% (1,431 patients) in the eICU cohort. Acetaminophen was administered in the early postoperative period to 4,185 patients (72%) and 2,737 patients (71%) in these 2 cohorts, respectively. In multivariable regression models, early postoperative use of acetaminophen was associated with a lower risk of severe AKI in both the MIMIC-III (adjusted hazard ratio [AHR], 0.86 [95% CI, 0.79-0.94]) and eICU (AHR, 0.84 [95% CI, 0.72-0.97]) cohorts. The benefit was consistent across sensitivity and subgroup analyses. LIMITATIONS: No data on acetaminophen dose. CONCLUSIONS: Early postoperative acetaminophen administration was independently associated with a lower risk of severe AKI in adults recovering from cardiac surgery. Prospective trials are warranted to assess the extent to which the observed association is causal and estimate the extent to which acetaminophen administration might prevent or reduce the severity of AKI. PLAIN-LANGUAGE SUMMARY: There is uncertainty about whether antioxidant medications such as acetaminophen may protect against kidney injury. Therefore, we evaluated the associations between acetaminophen use and kidney outcomes in adults recovering from cardiac surgery in 2 large clinical registries. Acetaminophen treatment was significantly associated with a 14%-16% lower risk of severe and any-stage acute kidney injury but similar risks of kidney replacement therapy and in-hospital mortality. Our findings suggest that acetaminophen use may protect against kidney injury in adult patients recovering from cardiac surgery.

Preoperative Ionized Magnesium Levels and Risk of Acute Kidney Injury After Cardiac Surgery.

RATIONALE & OBJECTIVE: Although postoperative acute kidney injury (AKI) is a serious complication after cardiac surgery, preventive measures are limited. Despite the known association of preoperative low magnesium levels with cardiac surgery-related atrial fibrillation, the association between preoperative magnesium concentration and postoperative AKI has not been fully elucidated. This study evaluated the association between preoperative serum magnesium level and the development of AKI after cardiac surgery. STUDY DESIGN: Retrospective observational cohort study. SETTING & PARTICIPANTS: Patients aged≥18 years who underwent cardiac surgery at 2 South Korean tertiary hospitals between 2006 and 2020 were identified from medical records. Patients with missing information, an estimated glomerular filtration rate<15mL/min/1.73m2, receiving maintenance dialysis, or a history of AKI treated by dialysis within 1 year before surgery were excluded. EXPOSURE: Preoperative serum magnesium levels. OUTCOME: Postoperative AKI within 48 hours after surgery, defined using the Acute Kidney Injury Network (AKIN) criteria, and dialysis-treated AKI within 30 days after surgery. ANALYTICAL APPROACH: Multivariable logistic regression analysis. RESULTS: Among the 9,766 patients (median age, 64.0 years; 60.1% male), postoperative AKI and dialysis-treated AKI were observed in 40.1% and 4.3% patients, respectively. Postoperative AKI was more prevalent in patients with lower serum magnesium levels (44.9%, 41.4%, 39.4%, and 34.8% in quartiles 1-4, respectively). Multivariable logistic regression analysis revealed that the odds ratios (ORs) for postoperative AKI were progressively larger across progressively lower quartiles of serum magnesium concentration (adjusted ORs of 1.53 [95% CI, 1.33-1.76], 1.29 [95% CI, 1.12-1.48], 1.15 [95% CI, 1.01-1.31] for quartiles 1-3, respectively, relative to quartile 4, P for trend<0.001). Preoperative hypomagnesemia (serum magnesium level<1.09mg/dL) was also significantly associated with AKI (adjusted OR, 1.39 [95% CI, 1.10-1.77]) and dialysis-treated AKI (adjusted OR, 1.67 [95% CI, 1.02-2.72]). LIMITATIONS: Causality could not be evaluated in this observational study. CONCLUSIONS: Lower serum magnesium levels were associated with a higher incidence of AKI in patients undergoing cardiac surgery.

Critical Care Nephrology: Core Curriculum 2020.

The intensive care unit (ICU) is a common source of high-acuity nephrology consultations. Although advanced chronic kidney disease is associated with increased ICU mortality, the prognosis of acute kidney injury (AKI) requiring renal replacement therapy is far worse, with short-term mortality rates that often exceed 50%. As such, it is essential that practicing nephrologists be comfortable caring for critically ill patients. This Core Curriculum article emphasizes the developments of the last decade since the last Core Curriculum installment on this topic in 2009. We focus on some of the most common causes of AKI in the critical care setting and use these AKI causes to delve into specific topics most relevant to critical care nephrology, including acute respiratory distress syndrome, extracorporeal membrane oxygenation, evolving concepts in fluid management, and shock. We conclude by reviewing the basics of palliative care nephrology and dialysis decision making in the ICU.

Acute kidney injury after heart transplant in young children: risk factors and outcomes.

BACKGROUND: Critical illness following heart transplantation can include acute kidney injury (AKI). Study objectives were to define the epidemiology of, risk factors for, or impact on outcomes of AKI after pediatric heart transplant. METHODS: Using data from a prospective study of 66 young children, we evaluated: (1) post-operative AKI rate (by pediatric modified RIFLE criteria); (2) pre, intra, and early post-operative AKI risk factors using stepwise logistic regression (3) effect of AKI on short-term outcomes (ventilation and length of pediatric intensive care unit (PICU) stay) using stepwise multiple regression. RESULTS: AKI occurred in 73 % of children. Pre-transplant ventilation and higher baseline estimated creatinine clearance (eCCl) were independent risk factors for AKI. Pre-operative inotrope use was associated with reduced risk of AKI. Tacrolimus level emerged as important in multivariable risk prediction. Children with AKI had a longer duration of ventilation and length of pediatric intensive care unit (PICU) stay, with AKI being an independent predictor. CONCLUSIONS: AKI was common after heart transplant and associated with more complicated early post-transplant course. Lower baseline eCCl was associated with lower incidence of AKI; this merits further investigation. The association of pre-operative inotropes with less AKI may reflect a pathophysiological mechanism or be a surrogate for clinical factors and management prior to transplant. Avoiding high tacrolimus levels may be a modifiable risk factor for AKI.

Diagnosis of Cardiac Surgery-Associated Acute Kidney Injury: State of the Art and Perspectives.

Diagnosis of cardiac surgery-associated acute kidney injury (CSA-AKI), a syndrome of sudden renal dysfunction occurring in the immediate post-operative period, is still sub-optimal. Standard CSA-AKI diagnosis is performed according to the international criteria for AKI diagnosis, afflicted with insufficient sensitivity, specificity, and prognostic capacity. In this article, we describe the limitations of current diagnostic procedures and of the so-called injury biomarkers and analyze new strategies under development for a conceptually enhanced diagnosis of CSA-AKI. Specifically, early pathophysiological diagnosis and patient stratification based on the underlying mechanisms of disease are presented as ongoing developments. This new approach should be underpinned by process-specific biomarkers including, but not limited to, glomerular filtration rate (GFR) to other functions of renal excretion causing GFR-independent hydro-electrolytic and acid-based disorders. In addition, biomarker-based strategies for the assessment of AKI evolution and prognosis are also discussed. Finally, special focus is devoted to the novel concept of pre-emptive diagnosis of acquired risk of AKI, a premorbid condition of renal frailty providing interesting prophylactic opportunities to prevent disease through diagnosis-guided personalized patient handling. Indeed, a new strategy of risk assessment complementing the traditional scores based on the computing of risk factors is advanced. The new strategy pinpoints the assessment of the status of the primary mechanisms of renal function regulation on which the impact of risk factors converges, namely renal hemodynamics and tubular competence, to generate a composite and personalized estimation of individual risk.

Cardiac Surgery Associated AKI Prevention Strategies and Medical Treatment for CSA-AKI.

Acute kidney injury (AKI) is common after cardiac surgery. To date, there are no specific pharmacological therapies. In this review, we summarise the existing evidence for prevention and management of cardiac surgery-associated AKI and outline areas for future research. Preoperatively, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers should be withheld and nephrotoxins should be avoided to reduce the risk. Intraoperative strategies include goal-directed therapy with individualised blood pressure management and administration of balanced fluids, the use of circuits with biocompatible coatings, application of minimally invasive extracorporeal circulation, and lung protective ventilation. Postoperative management should be in accordance with current KDIGO AKI recommendations.