Quality of life after acute kidney injury

Amino acids and the kidney; friends or foes?

PURPOSE OF REVIEW

Acute kidney injury (AKI) is common in hospitalized patients and is independently associated with morbidity and mortality. Moreover, AKI increases the risk of chronic kidney disease, which is a major healthcare problem. Currently, no single therapy has been proven to be effective in preventing AKI. The role of amino acids in the context of kidney function and AKI prevention has been controversial and most of the evidence is available from nutritional studies. However, knowledge of amino acids in recruiting renal functional reserve and their potential role to protect renal function under stress has recently expanded.

RECENT FINDINGS

The nephroprotective effects of amino acids were first postulated in 1973. Recently, this strategy gained renewed interest and has been more extensively studied, reintroducing their use in clinical situations characterized by a high incidence of AKI. Intravenous amino acids administration for kidney protection is now supported by a large multinational randomized double-blind controlled trial in cardiac surgery and by experimental and observational data. All such data support the rationale for a biologically and clinically important nephroprotective effect.

SUMMARY

The infusion of amino acids was recently found to reduce the incidence of AKI in cardiac surgery patients and surgical patients. This strategy for the protection of renal function is supported by a multicenter, international, double-blind randomized trial, with a huge potential for additional application in several clinical fields. Several mechanisms of action support the robustness of these findings and are summarized in this manuscript.

Acute kidney injury

Acute kidney injury (AKI) is a common, heterogeneous, multifactorial condition, which is part of the overarching syndrome of acute kidney diseases and disorders. This condition's incidence highest in low-income and middle-income countries. In the short term, AKI is associated with increased mortality, an increased risk of complications, extended stays in hospital, and high health-care costs. Long-term complications include chronic kidney disease, kidney failure, cardiovascular morbidity, and an increased risk of death. Several strategies are available to prevent and treat AKI in specific clinical contexts. Otherwise, AKI care is primarily supportive, focused on treatment of the underlying cause, prevention of further injury, management of complications, and short-term renal replacement therapy in case of refractory complications. Evidence confirming that AKI subphenotyping is necessary to identify precision-oriented interventions is growing. Long-term follow-up of individuals recovered from AKI is recommended but the most effective models of care remain unclear.

Amino Acid Infusion for Perioperative Functional Renal Protection: A Meta-analysis

OBJECTIVES

Acute kidney injury (AKI) is a common perioperative complication. To date, no single intervention has been proven effective for AKI prevention in this setting. However, intravenous amino acids (AA) administration may recruit renal functional reserve and, thereby, attenuate the perioperative loss of the glomerular filtration rate.

DESIGN

We performed a meta-analysis to assess the efficacy of AA infusion for perioperative renal functional protection.

SETTING AND PARTICIPANTS

We performed a meta-analysis of controlled studies in perioperative patients evaluating intravenous AA infusion versus any comparator.

MEASUREMENTS

The primary outcome was AKI at longest follow-up. We performed a random effects meta-analysis on the relative risk (RR) scale to assess the effect of AA infusion. We used a Bayesian approach to estimate the probability of benefit (RR < 1) for the primary outcome. Secondary outcomes included renal replacement therapy, serum creatinine, and estimated glomerular filtration rate. Tertiary outcomes included mechanical ventilation duration, intensive care unit and hospital length of stay and mortality (PROSPERO: CRD42024547225).

RESULTS

We identified 15 studies (14 randomized controlled trials and 1 prospective before-after study) reporting at least one outcome of interest (4,544 patients), with 6 studies (4,084 patients) reporting the primary outcome. AKI occurred 504 of 2,041 (24.7%) in AA patients versus 614 of 2,041 (30.1%) in controls (RR, 0.66; 95% confidence interval, 0.47-0.94; I2 = 50%; p = 0.02), which corresponded with a 99.1% probability of AKI reduction with AA. Moreover, consistent with these findings, AA decreased serum creatinine and hospital length of stay and increased the estimated glomerular filtration rate.

CONCLUSIONS

This meta-analysis suggests that AA administration likely decreased the perioperative incidence of AKI.

Biomarkers in acute kidney injury

Acute kidney injury (AKI) is a multifactorial syndrome with a high risk of short- and long-term complications as well as increased health care costs. The traditional biomarkers of AKI, serum creatinine and urine output, have important limitations. The discovery of new functional and damage/stress biomarkers has enabled a more precise delineation of the aetiology, pathophysiology, site, mechanisms, and severity of injury. This has allowed earlier diagnosis, better prognostication, and the identification of AKI sub-phenotypes. In this review, we summarize the roles and challenges of these new biomarkers in clinical practice and research.

Tumour lysis syndrome

Tumour lysis syndrome (TLS) represents a critical oncological emergency characterized by extensive tumour cell breakdown, leading to the swift release of intracellular contents into the systemic circulation, outpacing homeostatic mechanisms. This process results in hyperuricaemia (a by-product of intracellular DNA release), hyperkalaemia, hyperphosphataemia, hypocalcaemia and the accumulation of xanthine. These electrolyte and metabolic imbalances pose a significant risk of acute kidney injury, cardiac arrhythmias, seizures, multiorgan failure and, rarely, death. While TLS can occur spontaneously, it usually arises shortly after the initiation of effective treatment, particularly in patients with a large cancer cell mass (defined as ≥500 g or ≥300 g/m2 of body surface area in children). To prevent TLS, close monitoring and hydration to improve renal perfusion and urine output and to minimize uric acid or calcium phosphate precipitation in renal tubules are essential. Intervention is based on the risk of a patient of having TLS and can include rasburicase and allopurinol. Xanthine, typically enzymatically converted to uric acid, can accumulate when xanthine oxidases, such as allopurinol, are administered during TLS management. Whether measurement of xanthine is clinically useful to optimize the use of allopurinol or rasburicase remains to be determined.

The Road to Precision Medicine for Acute Kidney Injury

OBJECTIVES

Acute kidney injury (AKI) is a common form of organ dysfunction in the ICU. AKI is associated with adverse short- and long-term outcomes, including high mortality rates, which have not measurably improved over the past decade. This review summarizes the available literature examining the evidence of the need for precision medicine in AKI in critical illness, highlights the current evidence for heterogeneity in the field of AKI, discusses the progress made in advancing precision in AKI, and provides a roadmap for studying precision-guided care in AKI.

DATA SOURCES

Medical literature regarding topics relevant to precision medicine in AKI, including AKI definitions, epidemiology, and outcomes, novel AKI biomarkers, studies of electronic health records (EHRs), clinical trial design, and observational studies of kidney biopsies in patients with AKI.

STUDY SELECTION

English language observational studies, randomized clinical trials, reviews, professional society recommendations, and guidelines on areas related to precision medicine in AKI.

DATA EXTRACTION

Relevant study results, statements, and guidelines were qualitatively assessed and narratively synthesized.

DATA SYNTHESIS

We synthesized relevant study results, professional society recommendations, and guidelines in this discussion.

CONCLUSIONS

AKI is a syndrome that encompasses a wide range of underlying pathologies, and this heterogeneity has hindered the development of novel therapeutics for AKI. Wide-ranging efforts to improve precision in AKI have included the validation of novel biomarkers of AKI, leveraging EHRs for disease classification, and phenotyping of tubular secretory clearance. Ongoing efforts such as the Kidney Precision Medicine Project, identifying subphenotypes in AKI, and optimizing clinical trials and endpoints all have great promise in advancing precision medicine in AKI.

Comorbidities, acute kidney injury and long-term mortality in elderly patients hospitalized because of hip fracture: a moderation analysis

INTRODUCTION

Femoral fractures in elderly individuals present significant health challenges, often leading to increased morbidity and mortality. Acute kidney injury (AKI) during hospitalization further complicates outcomes, yet the interaction between AKI severity and comorbidities, as quantified by the Charlson Comorbidity Index (CCI), remains poorly understood in this population. This study aimed to assess the associations between AKI severity and the CCI and between AKI severity and one-year mortality postfemoral fracture in elderly patients.

METHODOLOGY

This study utilized data from the Multiparameter Intelligent Monitoring in Intensive Care (MIMIC-IV) database and focused on elderly patients (> 65 years) admitted with hip fractures. Patients were categorized based on AKI stage according to the KDIGO criteria and CCI scores. The primary outcome assessed was all-cause mortality one year after hospital discharge. The statistical analyses included logistic regression, Cox proportional hazards regression and moderation analysis with the Johnson-Neyman technique to evaluate associations between AKI and long-term mortality and between the CCI and long-term mortality.

RESULTS

The analysis included 1,955 patients and revealed that severe AKI (stages 2 and 3) was independently associated with increased one-year mortality. Notably, the CCI moderated these associations significantly. A lower CCI score was significantly correlated with greater mortality in patients with severe AKI. The impact of severe AKI was greater for those with a CCI as low as 3, more than doubling the observed one-year mortality rate. In contrast, higher CCI scores (≥8) did not significantly impact mortality. Sensitivity analyses supported these findings, underscoring the robustness of the observed associations.

CONCLUSION

This study elucidates the complex interplay between AKI severity and comorbidities and long-term mortality in elderly hip fracture patients. These findings underscore the importance of considering both AKI severity and comorbidity burden in prognostic assessments and intervention strategies for this vulnerable population. Targeted interventions tailored to individual risk profiles may help mitigate the impact of AKI on mortality outcomes, ultimately improving patient care and outcomes. Further research is warranted to explore the underlying mechanisms involved and refine risk stratification approaches in this population.