Management of acute renal failure in the elderly patient: a clinician's guide

Protective effects of astaxanthin solid lipid nanoparticle as a promising candidate against acute kidney injury in rats

Acute kidney injury (AKI) is a sudden onset of renal injury that occurs within a few hours or days. Ischemia-reperfusion (IR) is a major cause of AKI. There are multiple dysregulated mechanisms behind the pathogenesis of AKI and IR which urges the need for finding multi-targeting therapies. Natural products are multi-targeting agents with promising sources of anti-inflammation, antioxidant, and antiapoptosis. Among them, astaxanthin (AST) is a keto-carotenoid with a high antioxidant potential. Using solid lipid nanoparticles (SLNs) as a novel formulation of AST helps to increase its efficacy and reduce side effects against AKI. After SLN preparation and loading of AST, the physicochemical properties were evaluated, using scanning electron microscopy (SEM) and dynamic light scattering (DLS) tests. For the in vivo study, 28 rats were divided into four groups, including sham, ischemia/reperfusion (I/R), and groups receiving protective and daily doses of AST-SLN (5 and 10 mg/kg, i.p.) during all 5 days before ischemia. Exactly 24 h after ischemia, kidneys were isolated for histological studies, and also, serum levels of catalase (CAT), glutathione (GSH), nitrite, blood urea, and creatinine were measured. The results indicated that intraperitoneal administration of SLN-AST reduced oxidative stress by decreasing serum nitrite levels, while increasing CAT and GSH. SLN-AST also improved renal function by decreasing serum urea and creatinine and preventing tissue damage. Therefore, SLN-AST could be a hopeful adjuvant candidate to prevent AKI by modulating renal function, preventing tissue damage, and through antioxidant mechanisms.

The impact of serum potassium ion variability on 28-day mortality in ICU patients

OBJECTIVE

Potassium ion disorders are prevalent among patients in Intensive Care Units (ICUs), yet there is a notable deficiency in established protocols and supplemental plans for potassium management. This retrospective study conducted at a single center aims to explore the relationship between potassium levels, their variability, and the 28-day mortality rate in ICU patients.

METHODS

This study analyzed data from patients admitted to the ICU of the First Affiliated Hospital of Guangxi Medical University between October 2022 and October 2023. We assessed serum potassium variability using the coefficient of variation and categorized it into four quartile groups (Q1, Q2, Q3, Q4). Additionally, patients were classified into six groups based on serum potassium concentrations. The associations between these categories and the 28-day mortality rate were evaluated using binary logistic regression, adjusting for potential confounders.

RESULTS

A total of 506 patients and 12,099 potassium measurements were analyzed. The group with the lowest potassium variability (Q1) exhibited the lowest mortality rate at 21% (P<0.01). It is noteworthy that within 28 days in the intensive care unit (ICU), the coefficient of variation (CV) of potassium levels significantly increased among deceased patients compared to surviving patients (P < 0.01).

CONCLUSION

Significant variability in potassium levels is associated with an increased risk of 28-day mortality among ICU patients, underscoring the need for stringent monitoring and management of potassium levels in this population.

Optimisation of a Method for the Differentiation of Human Umbilical Cord-derived Mesenchymal Stem Cells Toward Renal Epithelial-like Cells

Human umbilical cord-derived mesenchymal stem cells (hucMSCs) can differentiate into multiple cell lineages, but few methods have been developed to generate kidney lineage cells. Due to their human origin, pluripotent nature and immunomodulatory properties, these stem cells are attractive candidates for clinical applications such as the repair or regeneration of damaged organs. This study evaluated the renal differentiation potential of hucMSCs, when exposed for 10 days to optimised concentrations of retinoic acid, activin-A and bone morphogenetic protein-7 (BMP-7) in various combinations, with and without the priming of the cells with a Wnt signalling pathway activator (CHIR99021). The hucMSCs were isolated and characterised according to surface marker expression (CD73, CD90, CD44, CD146 and CD8) and tri-lineage differentiation potential. The expression of key marker genes (OSR1, TBXT, HOXA13, SIX2, PAX2, KRT18 and ZO1) was examined by qRT-PCR. Specific marker protein expression (E-cadherin, cytokeratin-8 and cytokeratin-19) was analysed by immunocytochemistry. CHIR99021-primed cells treated with the retinoic acid, activin-A and BMP-7 cocktail showed epithelial cell-like differentiation - i.e. distinct phenotypic changes, as well as upregulated gene and protein expression, were observed that were consistent with an epithelial cell phenotype. Thus, our results showed that hucMSCs can efficiently differentiate into renal epithelial-like cells. This work may help in the development of focused therapeutic strategies, in which lineage-defined human stem cells can be used for renal regeneration.

Nephroprotective and antilithiatic activities of Costus spicatus (Jacq.) Sw.: Ethnopharmacological investigation of a species from the Dourados region, Mato Grosso do Sul State, Brazil

ETHNOPHARMACOLOGICAL RELEVANCE

Costus spicatus (Jacq.) Sw., also known as "cana-do-brejo," is a species that is widely used in Brazilian traditional medicine for the treatment of kidney diseases. However, no studies have evaluated its nephroprotective and antilithiatic effects.

AIM

To investigate nephroprotective and antilithiatic effects of C. spicatus in a preclinical model of acute kidney injury (AKI) and in vitro nephrolithiasis.

MATERIALS AND METHODS

C. spicatus leaves were collected directly from the natural environment in the Dourados region, Mato Grosso do Sul State, Brazil. The ethanol-soluble fraction of C. spicatus (ESCS) was obtained by infusion. Phytochemical characterization was performed by liquid chromatography coupled to diode array detector and mass spectrometer (LC-DAD-MS). We assessed whether ESCS has acute or prolonged diuretic activity. The nephroprotective effects of ESCS were evaluated in a model of AKI that was induced by glycerol (10 ml/kg, intramuscularly) in Wistar rats. Different doses of ESCS (30, 100, and 300 mg/kg) were administered orally for 5 days before the induction of AKI. Urinary parameters were measured on days 1, 3, 5, and 7. Twenty-four hours after the last urine collection, blood samples were obtained for the biochemical analysis. Blood pressure levels, renal vascular reactivity, renal tissue redox status, and histopathological changes were measured. Antilithiatic effects were evaluated by in vitro crystallization. Calcium oxalate precipitation was induced by sodium oxalate in urine samples with ESCS at 0.05, 0.5, and 5 mg/ml.

RESULTS

From LC-DAD-MS analyses, flavonoids, saponins and other phenolic compounds were determined in the composition of ESCS. Significant reductions of the excretion of urinary total protein, creatinine, sodium, and potassium were observed in the AKI group, with significant histopathological damage (swelling, vacuolization, necrosis, and inflammatory infiltration) in the proximal convoluted tubule. Treatment with ESCS exerted a significant nephroprotective effect by increasing the urinary excretion of total protein, urea, creatinine, sodium, potassium, calcium, and chloride. All of the groups that were treated with ESCS exhibited a reduction of histopathological lesions and significant modulation of the tissue redox state. We also observed a concentration-dependent effect of ESCS on the crystallization of urinary crystals, with reductions of the size and proportion of monohydrated crystals.

CONCLUSION

The data suggest that C. spicatus has nephroprotective and antilithiatic effects, suggesting possible effectiveness in its traditional use.

The Effect of Aging Physiology on Critical Care

Older patients experience a decline in their physiologic reserves as well as chronic low-grade inflammation named "inflammaging." Both of these contribute significantly to aging-related factors that alter the acute, subacute, and chronic response of these patients to critical illness, such as sepsis. Unfortunately, this altered response to stressors can lead to chronic critical illness followed by dismal outcomes and death. The primary goal of this review is to briefly highlight age-specific changes in physiologic systems majorly affected in critical illness, especially because it pertains to sepsis and trauma, which can lead to chronic critical illness and describe implications in clinical management.

A Review on Drug-Induced Nephrotoxicity: Pathophysiological Mechanisms, Drug Classes, Clinical Management, and Recent Advances in Mathematical Modeling and Simulation Approaches

A variety of marketed drugs belonging to various therapeutic classes are known to cause nephrotoxicity. Nephrotoxicity can manifest itself in several forms depending on the specific site involved as well as the underlying pathophysiological mechanisms. As they often coexist with other pathophysiological conditions, the steps that can be taken to treat them are often limited. Thus, drug-induced nephrotoxicity remains a major clinical challenge. Prior knowledge of risk factors associated with special patient populations and specific classes of drugs, combined with early diagnosis, therapeutic drug monitoring with dose adjustments, as well as timely prospective treatments are essential to prevent and manage them better. Most incident drug-induced renal toxicity is reversible only if diagnosed at an early stage and treated promptly. Hence, diagnosis at an early stage is the need of the hour to counter it. Significant recent advances in the identification of novel early biomarkers of nephrotoxicity are not beyond limitations. In such a scenario, mathematical modeling and simulation (M&S) approaches may help to better understand and predict toxicities in a clinical setting. This review summarizes pathophysiological mechanisms of drug-induced nephrotoxicity, classes of nephrotoxic drugs, management, prevention, and diagnosis in clinics. Finally, it also highlights some of the recent advancements in mathematical M&S approaches that could be used to better understand and predict drug-induced nephrotoxicity.

Correct use of non-indexed eGFR for drug dosing and renal drug-related problems at hospital admission

Purpose

Two to seven percent of the German adult population has a renal impairment (RI) with an estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73m². This often remains unrecognized and adjustment of drug therapy is lacking. To determine renal function in clinical routine, the CKD-EPI equation is used to calculate an indexed eGFR (ml/min/1.73m²). For drug dosing, it has to be individualized to a non-indexed eGFR (ml/min) by the patient’s body surface area. Here, we investigated the number of patients admitted to urological wards of a teaching hospital with RI between July and December 2016. Additionally, we correctly used the eGFR_non-indexed for drug and dosage adjustments and to analyse the use of renal risk drugs (RRD) and renal drug-related problems (rDRP).

Methods

In a retrospective observational study, urological patients with pharmacist-led medication reconciliation at hospital admission and eGFR_indexed (CKD-EPI) of 15–59 ml/min/1.73m² were identified. Indexed eGFR (ml/min/1.73m²) was recalculated with body surface area to non-indexed eGFR (ml/min) for correct drug dosing. Medication at admission was reviewed for RRD and based on the eGFR_non-indexed for rDRP, e.g. inappropriate dose or contraindication.

Results

Of 1320 screened patients, 270 (20.5%) presented with an eGFR_indexed of 15–59 ml/min/1.73m². After readjustment, 203 (15.4%) patients had an eGFR_non-indexed of 15–59 ml/min. Of these, 190 (93.6%) used ≥ 1 drugs at admission with 660 of 1209 (54.7%) drugs classified as RRD. At least one rDRP was identified in 115 (60.5%) patients concerning 264 (21.8%) drugs.

Conclusion

Renal impairment is a common risk factor for medication safety in urologic patients admitted to a hospital. Considerable shifts were seen in eGFR-categories when correctly calculating eGFR_non-indexed for drug dosing purposes. The fact that more than half of the study patients showed rDRP at hospital admission underlines the need to consider this risk factor appropriately.

Electronic supplementary material

The online version of this article (10.1007/s00228-020-02953-6) contains supplementary material, which is available to authorized users.

Magnitude of and Characteristics Associated With the Treatment of Calcium Channel Blocker-Induced Lower-Extremity Edema With Loop Diuretics

IMPORTANCE

Calcium channel blockers, specifically dihydropyridine calcium channel blockers (DH CCBs, eg, amlodipine), may cause lower-extremity edema. Anecdotal reports suggest this may result in a prescribing cascade, where DH CCB-induced edema is treated with loop diuretics.

OBJECTIVE

To assess the magnitude and characteristics of the DH CCB prescribing cascade.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study used a prescription sequence symmetry analysis to assess loop diuretic initiation before and after the initiation of DH CCBs among patients aged 20 years or older without heart failure. Data from a private insurance claims database from 2005 to 2017 was analyzed. Use of loop diuretics associated with initiation of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and other commonly used medications was used as negative controls. Data were analyzed from March 2019 through October 2019.

EXPOSURES

Initiation of DH CCB or negative control medications.

MAIN OUTCOMES AND MEASURES

The temporality of loop diuretic initiation relative to DH CCB or negative control initiation. Secular trend-adjusted sequence ratios (aSRs) with 95% CIs were calculated using data from 360 days before and after initiation of DH CCBs.

RESULTS

Among 1 206 093 DH CCB initiators, 55 818 patients (4.6%) (33 100 [59.3%] aged <65 years; 32 916 [59.0%] women) had a new loop diuretic prescription 360 days before or after DH CCB initiation, resulting in an aSR of 1.87 (95% CI, 1.84-1.90). An estimated 1.44% of DH CCB initiators experienced the prescribing cascade. The aSR was disproportionately higher among DH CCB initiators who were prescribed high doses (aSR, 2.20; 95% CI, 2.13-2.27), initiated amlodipine (aSR, 1.89; 95% CI, 1.86-1.93), were men (aSR, 1.96; 95% CI, 1.91-2.01), and used fewer antihypertensive classes (aSR, 2.55; 95% CI, 2.47-2.64). The evaluation of ACE inhibitors or ARBs as negative controls suggested hypertension progression may have tempered the incidence of the prescribing cascade (aSR for ACE inhibitors and ARBs, 1.27; 95% CI, 1.24-1.29).

CONCLUSIONS AND RELEVANCE

This study found an excessive use of loop diuretics following initiation of DH CCBs that cannot be completely explained by secular trends or hypertension progression. The prescribing cascade was more pronounced among those initially prescribed a high dose of DH CCBs.

[Kidney disease care for the elderly]

In our aging population, kidney disease management needs to take into account the frailty of the elderly. Standardized geriatric assessments can be proposed to help clinicians apprehend this dimension in their daily practice. These tools allow to better identify frail patients and offer them more personalized and harmless treatments. This article aims to focus on the kidney diseases commonly observed in elderly patients and analyze their specific nephrogeriatric care modalities. It should be noticed that all known kidney diseases can be also observed in the elderly, most often with a quite similar clinical presentation. This review is thus focused on the diseases most frequently and most specifically observed in elderly patients (except for monoclonal gammopathy associated nephropathies, out of the scope of this work), as well as the peculiarities of old age nephrological care.

An evaluation of a potential calcium channel blocker-lower-extremity edema-loop diuretic prescribing cascade

OBJECTIVES

Dihydropyridine calcium channel blockers (DH-CCB) are associated with lower-extremity edema (LEE). Loop diuretics have been used inappropriately to treat DH-CCB-associated LEE, constituting a prescribing cascade (PC). The aim of this work was to identify the prevalence and factors associated with potential DH-CCB-LEE-loop diuretic PC.

METHODS

The 2014 National Ambulatory Medical Care Survey was used to identify patient visits in which a DH-CCB was continued. The definition of a potential PC was the continuation or initiation of a loop diuretic in the absence of congestive heart failure, cancer, obstructive sleep apnea, chronic kidney disease or end-stage renal disease, obesity, or resistant hypertension. Multivariable logistic regression was used to identify factors related to a potential PC, including demographic information, number of medications, number of patient visits in the previous 12 months, and comorbid conditions.

RESULTS

Among the estimated 47.5 million patient visits in which a DH-CCB was continued, 4.6% had a potential PC. Visits in patients 65 to 84 years of age (odds ratio [OR] 2.56, 95% CI 1.20-5.43) and 85 years of age and older (OR 3.89, 95% CI 1.76-8.61) were more likely to have potential PC compared with patients 18 to 64 years of age. Visits in patients with 5 to 7 (OR 3.75, 95% CI 1.72-8.19), 8 to 11 (OR 2.20, 95% CI 1.09-4.44), and 12 or more (OR 5.23, 95% CI 2.29-11.94) medications were more likely to have potential PC compared with patients with 4 or fewer medications.

CONCLUSION

A potential DH-CCB-associated LEE loop diuretic PC was present in approximately 2.2 million patient visits in which DH-CCB was continued. Older age and an increasing number of concomitant medications were associated with this potential PC.

Drug-Induced Kidney Injury in the Elderly

The incidence of acute kidney injury in the elderly has grown over the past decade. One of the primary drivers is drug-induced nephrotoxicity, which is the result of a combination of the unique susceptibilities to kidney injury and the increased use of medications in the elderly population. Specific drug classes are associated with increased rates of kidney injury including agents that block the renin angiotensin system, antimicrobials, and chemotherapeutic agents. Mechanistically, injury may be due to hemodynamic effects, tubular or glomerular toxicity, and interstitial nephritis. Early recognition of nephrotoxicity is critical, as are preventative steps when applicable. Unfortunately, treatment for established drug-induced kidney injury is limited and supportive care is required. Limiting exposure to nephrotoxic drugs is critical in decreasing the incidence of acute kidney injury in the elderly patient.

Incidence of and Risk Factors for Severe Adverse Events in Elderly Patients Taking Angiotensin-Converting Enzyme Inhibitors or Angiotensin II Receptor Blockers after an Acute Myocardial Infarction

STUDY OBJECTIVE

To assess the incidence of and risk factors associated with severe adverse events in elderly patients who used angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) after an acute myocardial infarction (AMI).

DESIGN

Retrospective cohort study.

DATA SOURCES

Centers for Medicare & Medicaid Services Chronic Conditions Data Warehouse (Medicare service claims database), American Community Survey of the U.S. Census Bureau, and Multum Lexicon Drug database.

PATIENTS

A total of 101,588 eligible Medicare fee-for-service beneficiaries 66 years or older, who were hospitalized for AMI between January 1, 2008, and December 31, 2009, and used ACEIs or ARBs within 30 days after discharge.

MEASUREMENTS AND MAIN RESULTS

Primary outcomes were hospitalizations for acute renal failure (ARF) and hyperkalemia. The secondary outcome was discontinuation or suspension of ACEI/ARB therapy after a visit to a health care provider. The primary risk factors of interest were age, sex, race/ethnicity, and chronic kidney disease (CKD). Cumulative incidence curves and multivariable Fine-Gray proportional hazards models with 95% confidence intervals (CIs) were used with death as a competing risk in both intention-to-treat (ITT) and as-treated (AT) analyses. In the study cohort, 2.8% experienced ARF, 0.5% experienced hyperkalemia, and 63.7% discontinued ACEI/ARB therapy within 1 year after hospital discharge. Approximately half of the incidence of ARF and hyperkalemia occurred within 6 months after hospital discharge, but the cumulative incidence increased after 6 months. Patients older than 85 years had a higher rate of ARF (ITT hazard ratio [HR] 1.15, 95% CI 1.04-1.28) and hyperkalemia (ITT HR 1.33, 95% CI 1.05-1.68) compared with those aged 65-74 years. Patients with baseline CKD had higher rates of ARF (ITT HR 1.61, 95% CI 1.42-1.82), hyperkalemia (ITT HR 1.41, 95% CI 1.11-1.77), and ACEI/ARB therapy discontinuation or suspension (ITT HR 1.05, 95% CI 1.02-1.09).

CONCLUSION

We found a low incidence of ARF and hyperkalemia in elderly patients treated with ACEIs or ARBs after AMI hospitalization. However, a high rate of treatment discontinuation might prevent a higher rate of occurrence of these events. Long-term careful monitoring of severe adverse events and timely discontinuation of ACEIs or ARBs among elderly patients with advancing age and CKD after an AMI is warranted in clinical practice.

Prognostic role of lactate on mortality in younger and older patients with cardio-respiratory failure admitted to an acute intensive care unit

BACKGROUND AND AIM

Acidosis is able to induce negative changes of different organs that increase progressively with aging. At present it is not known whether the levels of lactate may differently influence the prognosis of younger and older patients. Thus, the aim of this study is to evaluate the prognostic value of lactate levels after admission of younger and older patients to an acute intensive care unit.

METHODS

Younger (<65 years, n = 118) and older (≥65 years, n = 165) patients admitted to an acute intensive care unit were prospectively enrolled and classified according to diagnosis of acute heart or/and respiratory failure. For each patient, APACHE II score, time of hospitalization and mortality, blood levels of lactate were collected.

RESULTS

Both in-hospital mortality and lactate >2.5 mmol/L at the admission was higher in the older than in the younger patients (42.4 vs. 20.3 %, p < 0.01 and 57.8 vs. 31.9 %, p < 0.01, respectively). Lactate level was higher in older than in the younger patients both at admission and after 24 h (3.9 ± 3.4 vs. 2.4 ± 2.2 mmol/L and 2.4 ± 2.0 vs. 1.4 ± 1.3 mmol, p < 0.01, respectively). Accordingly, multivariate analysis shows that lactate was predictive of mortality in younger (OR = 2.65, 95 % CI 1.62-5.24, p = 0.03) and even more in the older (OR = 4.74, 95 % CI 2.10-6.70, p < 0.01) patients.

CONCLUSIONS

Lactate concentration increase is associated with increased mortality in younger patients but, even more so, in older patients admitted to an acute intensive care unit. These results confirm the experimental evidence showing acidosis has a greater effect of leading to organ failure and higher mortality with increasing age.

The perfect storm: older adults and acute kidney injury

Older adults have a high risk for acute kidney injury (AKI), often necessitating critical care admission. The majority of older adults live with 1 or more chronic conditions requiring multiple medications, and when faced with acute illness increased vulnerability can lead to poor health outcomes. When combined with circumstances that exacerbate chronic conditions, clinicians may witness the perfect storm. Some factors that contribute to AKI risk include the aging kidney, sepsis, polypharmacy, and nephrotoxic medications and contrast media. This paper discusses specific risks and approaches to care for older adults with AKI who are in critical care.

Occludin Content Modulates Hydrogen Peroxide-Induced Increase in Renal Epithelial Paracellular Permeability

The ability of hydrogen peroxide (H2O2) to increase paracellular permeability of renal epithelial cell monolayers was examined and the role of occludin in this regulation was investigated. H2O2 treatment increased the paracellular movement of calcein, a marker for the leak pathway permeability, across monolayers of two renal epithelial cell lines, MDCK and LLC-PK1, in a concentration-dependent manner. At the same concentrations, H2O2 did not alter transepithelial resistance (TER) nor increase cell death. The magnitude of the H2O2-induced increase in leak pathway permeability was inversely related to cellular occludin protein content. H2O2 treatment did not produce any major change in total cellular content or Triton X-100-soluble or -insoluble fraction content of occludin protein. Occludin protein staining at the tight junction region was diminished following H2O2 treatment. The most dramatic effect of H2O2 was on the dynamic mobility of GFP-occludin into the tight junction region. H2O2 treatment slowed lateral movement of GFP-occludin into the tight junction region but not on the apical membrane. Further, removal of the cytoplasmic C-terminal region of occludin protein eliminated the effect of H2O2 on GFP-occludin lateral movement into the tight junction region. An increase in the mobile fraction of GFP-occludin was associated with a loss of response to H2O2. These data indicate that the H2O2-induced increase in renal epithelial cell paracellular permeability is mediated, at least in part, through occludin protein, possibly through a slowing of the rate of occludin movement into the tight junction region.

Critical Care Issues of the Geriatric Patient

Medical care of the geriatric patient is an important area of focus as the population ages and life expectancy increases. In particular, critical care of the geriatric patient will be especially affected, because geriatric patients will consume most critical care beds in the future and subsequently require increased use of resources. This review focuses on the physiologic effects of aging on all body systems. Focus on frailty and its effect on recovery from critical illness and its potential to modify the course of patient care will be important areas of research in the future.

Risk factors and outcomes of acute kidney injury after intracoronary stent implantation

BACKGROUND

Acute kidney injury following percutaneous coronary intervention (PCI) is associated with a worse outcome. However, the risk factors and outcomes of acute kidney injury (AKI) in patients after intracoronary stent implantation are still unknown.

METHODS

A retrospective case control study was done in 325 patients who underwent intracoronary stent implantation from January 2010 to March 2011 at the Drum Tower Hospital of Nanjing University School of Medicine. Those were excluded from the study if they had incomplete clinical data. The patients were divided into a normal group and a AKI group according to the standard of post-operation day 7 to identify AKI. The parameters of the patients included: 1) pre-operative ones: age, gender, hypertension, diabetes mellitus, cerebrovascular disease, left ventricular insufficiency, peripheral angiopathy, creatinine, urea nitrogen, estimated glomerular filtration rate (eGFR), hyperuricemia, proteinuria, emergency operation, hydration, medications (ACEI/ARBs, statins); 2) intraoperative ones: dose of contrast media, operative time, hypotension; and 3) postoperative one: hypotension. The parameters were analyzed with univariate analysis and multivariate logistical regression analysis.

RESULTS

Of the 325 patients, 51(15.7%) developed AKI. Hospital day and in-hospital mortality were increased significantly in the AKI-group. Univariate analysis showed that age, pre-operative parameters (left ventricular insufficiency, peripheral angiopathy, creatinine, urea nitrogen, estimated glomerular filtration rate, hyperuricemia, proteinuria, hydration), emergency operation, intraoperative parameters (operative time, hypotension) and postoperative hypotension were significantly different. However, multivariate logistic regression analysis revealed that increased age (OR=0.253, 95%CI=0.088-0.727), pre-operative proteinuria (OR=5.351, 95%CI=2.128-13.459), pre-operative left ventricular insufficiency (OR=8.704, 95%CI=3.170-23.898), eGFR≤60 ml/min/1.73 m(2) (OR=6.677, 95%CI=1.167-38.193), prolonged operative time, intraoperative hypotension (OR=25.245, 95%CI=1.001-1.034) were independent risk factors of AKI.

CONCLUSIONS

AKI is a common complication and associated with ominous outcome following intracoronary stent implantation. Increased age, pre-operative proteinuria, pre-operative left ventricular insufficiency, pre-operative low estimated glomerular filtration rate, prolonged operative time, intraoperative hypotension were the significant risk factors of AKI.

The aging kidney: increased susceptibility to nephrotoxicity

Three decades have passed since a series of studies indicated that the aging kidney was characterized by increased susceptibility to nephrotoxic injury. Data from these experimental models is strengthened by clinical data demonstrating that the aging population has an increased incidence and severity of acute kidney injury (AKI). Since then a number of studies have focused on age-dependent alterations in pathways that predispose the kidney to acute insult. This review will focus on the mechanisms that are altered by aging in the kidney that may increase susceptibility to injury, including hemodynamics, oxidative stress, apoptosis, autophagy, inflammation and decreased repair.

Acute kidney injury in the elderly hospitalized patients

OBJECTIVE

We aimed to evaluate acute kidney injury (AKI), occurrence of recovery and risk factors associated with permanent kidney injury and mortality in the elderly individuals.

DESIGN

Evidence for this study was obtained from retrospective cohort study from our center.

PATIENTS

A total of 193 patients (>65 years, mean age: 79.99 ± 6.93) with acute kidney injury were enrolled in this study between 2011 and 2012. PATIENTS with kidney failure or renal replacement therapy (RRT) history at admission were excluded.

INTERVENTION

Main outcome measurements: serum creatinine (SCr), estimated GFR (with CKD-Epi) and complete blood counts were evaluated at baseline and daily basis thereafter. The AKI was defined based on Kidney Disease Improving Global Outcomes (KDIGO) classification.

RESULTS

Among 193 patients, 43 (22%) patients required RRT. Mortality rate was 18% (n = 36) SCr levels were restored within 9.9 ± 6.7days on average (8-39 days). Sixteen patients (12.7%) required RRT after discharge. The mean hospital stay was 10.1 ± 8.6 days (7-41 days). Mortality rate of patients who have no renal recovery was higher (44.8% vs. 4.8%) than renal recovery group (p < 0.01).

CONCLUSION

The AKI represents a frequent complication in the elderly patients with longer hospital stay and increased mortality and morbidity. Our results show that dialytic support requirement is an independent predictor of permeant kidney injury in the elderly AKI patients. Older age, low diastolic blood pressure, high CRP and low hemoglobin levels were independent risk factors for mortality.

Acute kidney injury, sodium disorders, and hypercalcemia in the aging kidney: diagnostic and therapeutic management strategies in emergency medicine

This article summarizes the current literature regarding the structural and functional changes of the aging kidney and describes how these changes make the older patient more susceptible to acute kidney injury and fluid and electrolyte disorders. It discusses the clinical manifestations, evaluation, and management of hyponatremia and shows how the management of hypernatremia in geriatric patients involves addressing the underlying cause and safely correcting the hypernatremia. The current literature regarding evaluation and management of hypercalcemia in older patients is summarized. The management of severe hypercalcemia is discussed in detail. The evaluation and management of acute kidney injury is described.

The influence of mean arterial blood pressure during cardiopulmonary bypass on postoperative renal dysfunction in elderly patients

The aim of the study was to find out if there is an optimal mean arterial blood pressure (MABP) during cardiopulmonary bypass (CPB) for renal function in elderly patients during the early postoperative period. We analysed the data of 122 patients >70 years of age with normal preoperative renal function who had been subjected to coronary artery bypass grafting (CABG) procedures on CPB. Patients were divided into 3 groups, according to MABP during CPB: group MP (n=50) included patients whose MABP was maintained between 60-70 mmHg; group LP (n=36), the MABP was <60 mmHg; and group HP (n=36) where the MABP was >70 mmHg. The patients' clinical data were evaluated during the first three postoperative days. The rate of renal impairment (urine output <50ml/h) in the early postoperative period after cardiac surgery did not differ among the groups. Oliguria developed in 3 patients (6%) of the MP group, in 2 patients (5.6%) in the LP group and in 6 patients (16.7%) in the HP group (χ(2)=3.6, df=2, p=0.161). Evaluation of MABP on renal excretion showed that there was no difference in urine output among the groups. Serum creatinine levels at the end of the first postoperative day in groups MP, LP and HP were 102.7±20.1, 116.4±58.6 and 113.2±39.8 µmol/L, respectively (F=0.5, df=2, p=0.640). There were no significant differences among the groups at the end of the second and the third day either. Volume balance at the end of surgery and during the early postoperative period was similar in all groups. The need for diuretics did not differ among the groups. The length of postoperative hospital stay was not significantly different among the groups. Our study did not reveal any relationship between a MABP of 48-80 and postoperative renal dysfunction in elderly patients after CABG surgery.

Toward the optimal clinical use of the fraction excretion of solutes in oliguric azotemia

While the fractional excretion of solutes have long been considered excellent research tools to investigate tubular physiology, their clinical use has become common over the last 40 years in the diagnoses of many disorders; however, none have reached the clinical utility of the fractional excretion of sodium in the ability to distinguish pre-renal azotemia from acute tubular necrosis. Nevertheless, there are many drugs and medical conditions that interfere with that utility and recently other solutes, including urea, uric acid and lithium, have been recently investigated to improve the diagnostic ability in clinical situations where the fractional excretion of sodium is known to be unreliable. We review the tubular physiology of these solutes and show how the differences in tubular physiology might be exploited to develop a strategy for their optimal clinical use.

Urinary levels of regenerating islet-derived protein III β and gelsolin differentiate gentamicin from cisplatin-induced acute kidney injury in rats

A key aspect for the clinical handling of acute kidney injury is an early diagnosis, for which a new generation of urine biomarkers is currently under development including kidney injury molecule 1 and neutrophil gelatinase-associated lipocalin. A further diagnostic refinement is needed where one specific cause among several potentially nephrotoxic insults can be identified during the administration of multidrug therapies. In this study we identified increases in regenerating islet-derived protein III beta (reg IIIb) and gelsolin as potential differential urinary markers of gentamicin's nephrotoxicity. Indeed, urinary levels of both reg IIIb and gelsolin distinguish between the nephrotoxicity caused by gentamicin from that caused by cisplatin where these markers were not increased by the latter. Reg IIIb was found to be overexpressed in the kidneys of gentamicin-treated rats and excreted into the urine, whereas urinary gelsolin originated from the blood by glomerular filtration. Our results illustrate an etiological diagnosis of acute kidney injury through analysis of urine. Thus, our results raise the possibility of identifying the actual nephrotoxin in critically ill patients who are often treated with several nephrotoxic agents at the same time, thereby providing the potential for tailoring therapy to an individual patient, which is the aim of personalized medicine.

Achievements and challenges in bioartificial kidney development

Bioartificial kidneys (BAKs) combine a conventional hemofilter in series with a bioreactor unit containing renal epithelial cells. The epithelial cells derived from the renal tubule should provide transport, metabolic, endocrinologic and immunomodulatory functions. Currently, primary human renal proximal tubule cells are most relevant for clinical applications. However, the use of human primary cells is associated with many obstacles, and the development of alternatives and an unlimited cell source is one of the most urgent challenges. BAKs have been applied in Phase I/II and Phase II clinical trials for the treatment of critically ill patients with acute renal failure. Significant effects on cytokine concentrations and long-term survival were observed. A subsequent Phase IIb clinical trial was discontinued after an interim analysis, and these results showed that further intense research on BAK-based therapies for acute renal failure was required. Development of BAK-based therapies for the treatment of patients suffering from end-stage renal disease is even more challenging, and related problems and research approaches are discussed herein, along with the development of mobile, portable, wearable and implantable devices.

Acute kidney injury in the elderly

The aging kidney undergoes several important anatomic and physiologic changes that increase the risk of acute kidney injury (formerly acute renal failure) in the elderly. This article reviews these changes and discusses the diagnoses frequently encountered in the elderly patient with acute kidney injury. The incidence, staging, evaluation, management, and prognosis of acute kidney injury are also examined with special focus given to older adults.

Clinical evidence from ONTARGET: the value of an angiotensin II receptor blocker and an angiotensin-converting enzyme inhibitor

The Heart Outcomes Prevention Evaluation study established the angiotensin-converting enzyme inhibitor ramipril, versus placebo, for prevention of cardiovascular events in high-risk patients. The ONgoing Telmisartan Alone and in combination with Ramipril Global Endpoint Trial (ONTARGET) was later conducted in similar high-risk patients using multifactorial treatment to control hypertension, platelet aggregation, and dyslipidemia, while comparing ramipril, telmisartan, or their combination, without placebo. In ONTARGET, the first angiotensin II receptor blocker-based study to be performed in a broader population of patients without congestive heart failure and/or left ventricular hypertrophy/dysfunction, telmisartan provided cardiovascular protection that was noninferior to ramipril. However, greater blockade of the renin-angiotensin system, using their combination, was not superior to ramipril alone. Telmisartan was better tolerated than ramipril in this high-risk population: notably, the incidence of cough and angioedema was significantly lower with telmisartan alone. Thus, telmisartan provides comparable efficacy to ramipril with less adverse events, which may encourage patient compliance.

Acute kidney injury in the elderly: pathogenesis, diagnosis and therapy

Elderly patients, especially those with chronic kidney disease, are at least a 3.5-fold higher risk for the development of acute kidney injury (AKI). With aging, renal functional reserve is lower owing to specific cellular changes that affect function. Molecular studies are elucidating these cellular changes and offer the prospect of designing novel therapeutics. The spectrum of AKI in elderly patients is wide but is over-represented by prerenal and postrenal (obstructive) etiologies. This reflects potentially nephrotoxic clinical variables, such as combordid states, impaired baseline renal function, polypharmacy and an increase in high-risk procedures. In this population, the development of AKI can lead to longer hospital stays, higher mortality rates and an increased risk for the development of chronic kidney disease and end-stage renal disease. Careful attention to clinical risk factors, avoidance of nephrotoxic insults and meticulous supportive care for patients who develop AKI is critical in alleviating the burden of this problem.