Normotensive ischemic acute renal failure

Impact of Renal Impairment on Intensive Blood-Pressure-Lowering Therapy and Outcomes in Intracerebral Hemorrhage: Results From ATACH-2

Background and Objective

The clinical effect of renal impairment on intracerebral hemorrhage (ICH) is unknown. This study sought to assess whether estimated glomerular filtration rate (eGFR) affects clinical outcomes or modifies the efficacy of intensive systolic blood pressure (BP) control (target, 110–139 mm Hg) against the standard (target, 140–179 mm Hg) among patients with ICH.

Methods

We conducted post hoc analyses of ATACH-2, a randomized, 2-group, open-label trial. The baseline eGFR of each eligible patient was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. The outcome of interest was death or disability at 90 days. Multivariate logistic regression models were used for analysis.

Results

Among the 1,000 patients randomized, 974 were analyzed. The median baseline eGFR was 88 (interquartile range, 68, 99) mL/min/1.73 m²; 451 (46.3%), 363 (37.3%), and 160 (16.4%) patients had baseline eGFR values of ≥90, 60–89, and <60 mL/min/1.73 m², respectively. Compared with normal eGFR (≥90 mL/min/1.73 m²), higher odds of death or disability were noted among those with eGFR values of <60 mL/min/1.73 m² (adjusted odds ratio [OR], 2.02; 95% confidence interval [CI], 1.25–3.26) but not among those with eGFR values of 60–89 mL/min/1.73 m² (OR, 1.01; 95% CI, 0.70–1.46). The odds of death or disability were significantly higher in the intensive arm among patients with decreased eGFR; the ORs were 0.89 (95% CI, 0.55–1.44), 1.13 (0.68–1.89), and 3.60 (1.47–8.80) in patients with eGFR values of ≥90, 60–89, and <60 mL/min/1.73 m², respectively (p for interaction = 0.02).

Discussion

Decreased eGFR is associated with unfavorable outcomes following ICH. The statistically significant interaction between the eGFR group and treatment assignment raised safety concerns for the intensive BP-lowering therapy among patients with renal impairment.

Trial Registration Information

Clinicaltrials.gov identifier: NCT01176565.

Classification of Evidence

This study provides Class II evidence that in spontaneous ICH, decreased eGFR identifies patients at risk of death or disability following intensive BP control.

Impact of acute kidney injury in patients prescribed angiotensin-converting enzyme inhibitors over the first two years of life

BACKGROUND

The association of long-term acute kidney injury (AKI) risk with angiotensin-converting enzyme (ACE) inhibitor use in neonates/infants is poorly understood. We examined this association to identify potential AKI risk factors.

METHODS

We retrospectively evaluated 119 children aged < 2 years (72 boys; median age, 5.0 months) who received ACE inhibitors for congenital heart disease for ≥ 6 months between January 2009 and June 2019. We monitored the occurrence of AKI, defined according to the Kidney Disease Improving Global Outcomes guidelines. Demographic and clinical data were extracted from medical records. Risk factors associated with AKI onset were identified by a Cox proportional hazards regression analysis of variables previously identified as risk factors of AKI and those significant in a univariate analysis.

RESULTS

Thirty-three of 119 patients (28%) developed AKI at a median follow-up of 1.3 years (interquartile range, 0.8-3.2 years). AKI incidence was 1257 events per 10,000 patient-years. Concomitant tolvaptan use (hazard ratio [HR], 3.81; 95% confidence interval [CI], 1.82-7.97; P < 0.01) and Down syndrome (HR, 3.22; 95% CI, 1.43-7.29; P < 0.01) were identified as independent risk factors of AKI onset.

CONCLUSIONS

AKI was strongly associated with concomitant tolvaptan use and Down syndrome in our study population. Physicians should consider these factors when prescribing ACE inhibitors for neonates/infants. Low-dose ACE inhibitors slow CKD progression because of their antifibrotic properties. ACE inhibitors may be beneficial for patients with Down syndrome who have underlying CKD in a non-acute setting. Therefore, they should be administered to such patients with caution.

Pro Re Nata Antihypertensive Medications and Adverse Outcomes in Hospitalized Patients: A Propensity-Matched Cohort Study

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The potential renal toxicity of silver nanoparticles after repeated oral exposure and its underlying mechanisms

BACKGROUND

Silver nanoparticles (AgNPs) can accumulate in various organs after oral exposure. The main objective of the current study is to evaluate the renal toxicity induced by AgNPs after repeated oral exposure and to determine the relevant molecular mechanisms.

METHODS

In this study, 40 male Wistar rats were treated with solutions containing 30, 125, 300, and 700 mg/kg of AgNPs. After 28 days of exposure, histopathological changes were assessed using hematoxylin-eosin (H&E), Masson's trichrome, and periodic acid-Schiff (PAS) staining. Apoptosis was quantified by TUNEL and immunohistochemistry of caspase-3, and the level of expression of the mRNAs of growth factors was determined using RT-PCR.

RESULTS

Histopathologic examination revealed degenerative changes in the glomeruli, loss of tubular architecture, loss of brush border, and interrupted tubular basal laminae. These changes were more noticeable in groups treated with 30 and 125 mg/kg. The collagen intensity increased in the group treated with 30 mg/kg in both the cortex and the medulla. Apoptosis was much more evident in middle-dose groups (i.e., 125 and 300 mg/kg). The results of RT-PCR indicated that Bcl-2 and Bax mRNAs upregulated in the treated groups (p < 0.05). Moreover, the data related to EGF, TNF-α, and TGF-β1 revealed that AgNPs induced significant changes in gene expression in the groups treated with 30 and 700 mg/kg compared to the control group.

CONCLUSION

Our observations showed that AgNPs played a critical role in in vivo renal toxicity.

Telmisartan Exacerbates Cisplatin-Induced Nephrotoxicity in a Mouse Model

Cisplatin (CDDP; cis-diamine dichloroplatinum)-induced nephrotoxicity is the main reason for dose limitations, which can reduce the efficacy of cancer treatment. Lower blood pressure and administration of renin angiotensin system (RAS) inhibitors have been reported as factors that exacerbate CDDP-induced nephrotoxicity; however, the detailed mechanisms remain unknown and the results of previous studies are conflicting. In this study, we examined the influence of various hypotensive drugs, including RAS inhibitors and calcium channel blockers, on CDDP-induced nephrotoxicity in BALB/c mice. The mice were divided into nine groups: (1) CDDP group (15 mg/kg CDDP), (2) AML group (5 mg/kg amlodipine), (3) ENA group (2.5 mg/kg enalapril), (4) telmisartan (TEL) group (10 mg/kg telmisartan), (5) LOS group (10 mg/kg losartan), (6) CDDP + AML group, (7) CDDP + ENA group, (8) CDDP + TEL group, and (9) CDDP + LOS group. Nephrotoxicity was evaluated by measuring serum creatinine (CRE) and blood urea nitrogen (BUN) levels. In addition, the kidney sections were stained with Masson's trichrome and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) to assess the renal fibrosis area and apoptotic area. Serum CRE and BUN levels were increased in the CDDP + ENA, CDDP + LOS, and CDDP + TEL groups compared to those in the CDDP alone group, and the CDDP + AML group showed an increasing trend. However, there was no correlation between ∆CRE or ∆BUN levels and ∆ systolic blood pressure. The CDDP + TEL group showed a significant increase in the renal fibrosis area. These results suggest that exacerbation of CDDP-induced nephrotoxicity is not correlated with systolic blood pressure but is associated with administration of RAS inhibitors, particularly TEL.

Diabetic kidney disease: new clinical and therapeutic issues. Joint position statement of the Italian Diabetes Society and the Italian Society of Nephrology on "The natural history of diabetic kidney disease and treatment of hyperglycemia in patients with type 2 diabetes and impaired renal function"

Aims

This joint document of the Italian Diabetes Society and the Italian Society of Nephrology reviews the natural history of diabetic kidney disease (DKD) in the light of the recent epidemiological literature and provides updated recommendations on anti-hyperglycemic treatment with non-insulin agents.

Data Synthesis

Recent epidemiological studies have disclosed a wide heterogeneity of DKD. In addition to the classical albuminuric phenotype, two new albuminuria-independent phenotypes have emerged, i.e., “nonalbuminuric renal impairment” and “progressive renal decline”, suggesting that DKD progression toward end-stage kidney disease (ESKD) may occur through two distinct pathways, albuminuric and nonalbuminuric. Several biomarkers have been associated with decline of estimated glomerular filtration rate (eGFR) independent of albuminuria and other clinical variables, thus possibly improving ESKD prediction. However, the pathogenesis and anatomical correlates of these phenotypes are still unclear. Also the management of hyperglycemia in patients with type 2 diabetes and impaired renal function has profoundly changed during the last two decades. New anti-hyperglycemic drugs, which do not cause hypoglycemia and weight gain and, in some cases, seem to provide cardiorenal protection, have become available for treatment of these individuals. In addition, the lowest eGFR safety thresholds for some of the old agents, particularly metformin and insulin secretagogues, have been reconsidered.

Conclusions

The heterogeneity in the clinical presentation and course of DKD has important implications for the diagnosis, prognosis, and possibly treatment of this complication. The therapeutic options for patients with type 2 diabetes and impaired renal function have substantially increased, thus allowing a better management of these individuals.

Ultra-small natural product based coordination polymer nanodots for acute kidney injury relief

Acute kidney injury (AKI) is frequently associated with reactive oxygen species (ROS) and causes high mortality in clinics annually, and nanotechnology-mediated antioxidative therapy is emerging as a novel strategy for AKI treatment. Herein, four kinds of natural antioxidants are able to coordinate with iron (Fe) ions to form ultra-small coordination polymer nanodots (CPNs) with good water dispersibility and strong ROS scavenging ability. In particular, Fe-curcumin CPNs (Fe-Cur CPNs) are applied for cellular ROS scavenging and rhabdomyolysis-induced AKI relief.

Predictors of postoperative acute kidney injury in patients undergoing hip fracture surgery: A systematic review and meta-analysis

BACKGROUND

The present study aimed to summarize the predictors of acute kidney injury (AKI) in patients after hip surgery.

METHODS

A literature search was performed using PubMed, EMBASE, Cochrane Library, and Web of Science for studies assessing the predictors of AKI after hip fracture surgery. Pooled odds ratio (OR) and mean difference (MD) of those who experienced AKI compared to those who did not were calculated for each variable. Evidence was assessed using the Newcastle-Ottawa Scale.

RESULTS

Ten studies with 34 potential factors were included in the meta-analysis. In the primary analysis, 12 factors were associated with AKI, comprising males (OR 1.25; 95% confidence interval (CI) 1.14-1.36), advanced age (MD 2.28; 95% CI 0.80-3.75), myocardial infarction (OR 1.39; 95% CI 1.18-1.63), hypertension (OR 1.46; 95% CI 1.13-1.89), diabetes (OR 1.84; 95% CI 1.40-2.42), chronic kidney disease (OR 3.66; 95% CI 2.21-6.07), hip arthroplasty (OR 1.35; 95% CI 1.22-1.50), angiotensin-converting enzyme inhibitors/angiotensin receptor blockers use (OR 2.28; 95% CI 1.68-3.08), more intraoperative blood loss (MD 44.06; 95% CI 2.88-85.24), higher preoperative blood urea nitrogen levels (MD 5.29; 95% CI 3.38-7.20), higher preoperative serum creatinine levels (MD 0.4; 95% CI 0.26-0.53), and lower preoperative estimated glomerular filtration rate (MD -19.59; 95% CI -26.92--12.26). Another 13 factors related to AKI in individual studies were identified in the systematic review.

CONCLUSION

Related prophylaxis strategies should be implemented in patients involved with the above-mentioned characteristics to prevent AKI after hip surgery.

Low hemoglobin levels are independently associated with neonatal acute kidney injury: a report from the AWAKEN Study Group

BACKGROUND

Studies in adults showed a relationship between low hemoglobin (Hb) and acute kidney injury (AKI). We performed this study to evaluate this association in newborns.

METHODS

We evaluated 1891 newborns from the Assessment of Worldwide AKI Epidemiology in Neonates (AWAKEN) database. We evaluated the associations for the entire cohort and 3 gestational age (GA) groups: <29, 29-<36, and ≥36 weeks' GA.

RESULTS

Minimum Hb in the first postnatal week was significantly lower in neonates with AKI after the first postnatal week (late AKI). After controlling for multiple potential confounders, compared to neonates with a minimum Hb ≥17.0 g/dL, both those with minimum Hb ≤12.6 and 12.7-14.8 g/dL had an adjusted increased odds of late AKI (aOR 3.16, 95% CI 1.44-6.96, p = 0.04) and (aOR 2.03, 95% CI 1.05-3.93; p = 0.04), respectively. This association was no longer evident after controlling for fluid balance. The ability of minimum Hb to predict late AKI was moderate (c-statistic 0.68, 95% CI 0.64-0.72) with a sensitivity of 65.9%, a specificity of 69.7%, and a PPV of 20.8%.

CONCLUSIONS

Lower Hb in the first postnatal week was associated with late AKI, though the association no longer remained after fluid balance was included.

IMPACT

The current study suggests a possible novel association between low serum hemoglobin (Hb) and neonatal acute kidney injury (AKI). The study shows that low serum Hb levels in the first postnatal week are associated with increased risk of AKI after the first postnatal week. This study is the first to show this relationship in neonates. Because this study is retrospective, our observations cannot be considered proof of a causative role but do raise important questions and deserve further investigation. Whether the correction of low Hb levels might confer short- and/or long-term renal benefits in neonates was beyond the scope of this study.

Identification of a Novel Natriuretic Protein in Patients With Cerebral-Renal Salt Wasting-Implications for Enhanced Diagnosis

BACKGROUND

The most vexing problem in hyponatremic conditions is to differentiate the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) from cerebral/renal salt wasting (C-RSW). Both have identical clinical parameters but diametrically opposite therapeutic goals of water- restricting water-logged patients with SIADH or administering salt and water to dehydrated patients with C-RSW. While C-RSW is considered a rare condition, the report of a high prevalence of C-RSW in the general hospital wards creates an urgency to differentiate one syndrome from the other on first encounter. We decided to identify the natriuretic factor (NF) we previously demonstrated in plasma of neurosurgical and Alzheimer diseases (AD) who had findings consistent with C-RSW.

METHODS

We performed the same rat renal clearance studies to determine natriuretic activity (NA) in serum from a patient with a subarachnoid hemorrhage (SAH) and another with AD and demonstrated NA in their sera. The sera were subjected to proteomic and SWATH (Sequential Windowed Acquisition of All) analyses which identified increased levels of haptoglobin related protein (Hpr) without signal peptide (Hpr-WSP).

RESULTS

Recombinant Hpr with His tag at the N terminus had no NA. Hpr-WSP had a robust NA in a dose-dependent manner when injected into rats. Serum after recovery from C-RSW in the SAH patient had no NA.

CONCLUSIONS

Hpr-WSP may be the NF in C-RSW which should be developed as a biomarker to differentiate C-RSW from SIADH on first encounter, introduces a new syndrome of C-RSW in AD and can serve as a proximal diuretic to treat congestive heart failure.

Therapeutic approaches targeting renin-angiotensin system in sepsis and its complications

Sepsis, caused by the inappropriate host response to infection, is characterized by excessive inflammatory response and organ dysfunction, thus becomes a critical clinical problem. Commonly, sepsis may progress to septic shock and severe complications, including acute kidney injury (AKI), acute respiratory distress syndrome (ARDS), sepsis-induced myocardial dysfunction (SIMD), liver dysfunction, cerebral dysfunction, and skeletal muscle atrophy, which predominantly contribute to high mortality. Additionally, the global pandemic of coronavirus disease 2019 (COVID-19) raised the concern of development of effectve therapeutic strategies for viral sepsis. Renin-angiotensin system (RAS) may represent as a potent therapeutic target for sepsis therapy. The emerging role of RAS in the pathogenesis of sepsis has been investigated and several preclinical and clinical trials targeting RAS for sepsis treatment revealed promising outcomes. Herein, we attempt to review the effects and mechanisms of RAS manipulation on sepsis and its complications and provide new insights into optimizing RAS interventions for sepsis treatment.

New strategies to optimize renal haemodynamics

PURPOSE OF REVIEW

This review discusses the macrocirculatory and microcirculatory aspects of renal perfusion, as well as novel methods by which to measure renal blood flow. Finally, therapeutic options are briefly discussed, including renal-specific microcirculatory effects.

RECENT FINDINGS

The optimal mean arterial pressure (MAP) needed for preservation of renal function has been debated but is most likely a MAP of 60-80 mmHg. In addition, attention should be paid to renal outflow pressure, typically central venous pressure. Heterogeneity in microcirculation can exist and may be mitigated through appropriate use of vasopressors with unique microcirculatory effects. Excessive catecholamines have been shown to be harmful and should be avoided. Both angiotensin II and vasopressin may improve glomerular flow through a number of mechanisms. Macrocirculatory and microcirculatory blood flow can be measured through a number of bedside ultrasound modalities, sublingual microscopy and urinary oxygen measurement, SUMMARY: Acute kidney injury (AKI) is a common manifestation of organ failure in shock, and avoidance of hemodynamic instability can mitigate this risk. Measurement of renal haemodynamics is not routinely performed but may help to guide therapeutic goals. A thorough understanding of pathophysiology, measurement techniques and therapeutic options may allow for a personalized approach to blood pressure management in patients with septic shock and may ultimately mitigate AKI.

Association between levosimendan, postoperative AKI, and mortality in cardiac surgery: Insights from the LEVO-CTS trial

OBJECTIVES

We aimed to evaluate the association between levosimendan treatment and acute kidney injury (AKI) as well as assess the clinical sequelae of AKI in cardiac surgery patients with depressed left ventricular function (ejection fraction <35%).

METHODS

Patients in the LEVO-CTS trial undergoing on-pump coronary artery bypass grafting (CABG), valve, or CABG/valve surgery were stratified by occurrence and severity of postoperative AKI using the AKIN classification. The association between levosimendan infusion and AKI was modeled using multivariable regression.

RESULTS

Among 854 LEVO-CTS patients, 231 (27.0%) experienced postoperative AKI, including 182 (21.3%) with stage 1, 35 (4.1%) with stage 2, and 14 (1.6%) with stage 3 AKI. The rate of AKI was similar between patients receiving levosimendan or placebo. The odds of 30-day mortality significantly increased by AKI stage compared to those without AKI (stage 1: adjusted odds ratio [aOR] 2.0, 95% confidence interval [CI] 0.8-4.9; stage 2: aOR 9.1, 95% CI 3.2-25.7; stage 3: aOR 12.4, 95% CI 3.0-50.4). No association was observed between levosimendan, AKI stage, and odds of 30-day mortality (interaction P = .69). Factors independently associated with AKI included increasing age, body mass index, diabetes, and increasing baseline systolic blood pressure. Increasing baseline eGFR and aldosterone antagonist use were associated with a lower risk of AKI.

CONCLUSIONS

Postoperative AKI is common among high-risk patients undergoing cardiac surgery and associated with significantly increased risk of 30-day death or dialysis. Levosimendan was not associated with the risk of AKI.

PEGylated and Acylated Elabela Analogues Show Enhanced Receptor Binding, Prolonged Stability, and Remedy of Acute Kidney Injury

Acute kidney injury (AKI), mostly caused by renal ischemia-reperfusion (I/R) injury and nephrotoxins, is characterized by rapid deterioration in renal-functions without effective drug treatment available. Through activation of a G protein-coupled receptor APJ, a furin-cleaved fragment of Elabela (ELA[22-32], E11), an endogenous APJ ligand, protects against renal I/R injury. However, the poor plasma stability and relatively weak APJ-binding ability of E11 limit its application. To address these issues, we rationally designed and synthesized a set of E11 analogues modified by palmitic acid (Pal) or polyethylene glycol; improved plasma stability and APJ-binding capacity of these analogues were achieved. In cultured renal tubular cells, these analogues protected against hypoxia-reperfusion or cisplatin-caused injury. For renal I/R-injured mice, these analogues showed improved reno-protective effects than E11; notably, Pal-E11 showed therapeutic effects at 24 h post I/R injury. These results present ELA analogues as potential therapeutic options in managing AKI.

Predictive effect of salt intake on patient and kidney survival in non-dialysis CKD: competing risk analysis in older versus younger patients under nephrology care

BACKGROUND

The optimal level of salt intake remains ill-defined in non-dialysis chronic kidney disease (CKD) patients under regular nephrology care. This unanswered question becomes critical in older patients who are exposed to higher risk of worsening of cardiorenal disease due to volemic changes.

METHODS

In this pooled analysis of four prospective studies in CKD, we compared the risk of all-cause mortality and end-stage kidney disease (ESKD) between patients ≤65 and >65 years of age stratified by salt intake level (<6, 6-8 and >8 g/day) estimated from two measurements of 24-h urinary sodium.

RESULTS

The cohort included 1785 patients. The estimated glomerular filtration rate was 37 ± 21 mL/min/1.73 m2 overall, 41 ± 25 in younger patients and 34 ± 16 in older patients (P < 0.001). The median 24-h urinary sodium excretion was 143 mEq [interquartile range (IQR) 109-182] in all, 147 (112-185) in younger patients and 140 (106-179) in older patients (P = 0.012). Salt intake was ≤6, 6-8 and >8 g sodium chloride/day in 21.9, 26.2 and 52.0% of older patients and 18.6, 25.2 and 56.2% in younger patients, respectively (P = 0.145). During a median follow-up of 4.07 years we registered 383 ESKD and 260 all-cause deaths. In the whole cohort, the risks of ESKD and all-cause death did not differ by salt intake level. In older patients, ESKD risk [multi-adjusted hazard ratio (HR) and 95% confidence interval (CI)] was significantly lower at salt intakes of 6-8 g/day [HR 0.577 (95% CI 0.361-0.924)] and >8 g/day [HR 0.564 (95% CI 0.382-0.833)] versus the reference group (<6 g/day). Mortality risk was higher in older versus younger patients, with no difference across salt intake categories. No effect of salt intake on ESKD and mortality was observed in younger patients.

CONCLUSIONS

CKD patients under nephrology care show a moderate salt intake (8.4 g/day) that is lower in older versus younger patients. In this context, older patients are not exposed to higher mortality across different levels of salt intake, while salt intake <6 g/day poses a greater risk of ESKD.

Novel Evidence of Acute Kidney Injury in COVID-19

The coronavirus 2019 (COVID-19) pandemic has caused a huge impact on health and economic issues. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes cellular damage by entry mediated by the angiotensin-converting enzyme 2 of the host cells and its conjugation with spike proteins of SARS-CoV-2. Beyond airway infection and acute respiratory distress syndrome, acute kidney injury is common in SARS-CoV-2-associated infection, and acute kidney injury (AKI) is predictive to multiorgan dysfunction in SARS-CoV-2 infection. Beyond the cytokine storm and hemodynamic instability, SARS-CoV-2 might directly induce kidney injury and cause histopathologic characteristics, including acute tubular necrosis, podocytopathy and microangiopathy. The expression of apparatus mediating SARS-CoV-2 entry, including angiotensin-converting enzyme 2, transmembrane protease serine 2 (TMPRSS2) and a disintegrin and metalloprotease 17 (ADAM17), within the renal tubular cells is highly associated with acute kidney injury mediated by SARS-CoV-2. Both entry from the luminal and basolateral sides of the renal tubular cells are the possible routes for COVID-19, and the microthrombi associated with severe sepsis and the dysregulated renin-angiotensin-aldosterone system worsen further renal injury in SARS-CoV-2-associated AKI. In the podocytes of the glomerulus, injured podocyte expressed CD147, which mediated the entry of SARS-CoV-2 and worsen further foot process effacement, which would worsen proteinuria, and the chronic hazard induced by SARS-CoV-2-mediated kidney injury is still unknown. Therefore, the aim of the review is to summarize current evidence on SARS-CoV-2-associated AKI and the possible pathogenesis directly by SARS-CoV-2.

Physiological factors characterizing heat-vulnerable older adults: A narrative review

More frequent and intense periods of extreme heat (heatwaves) represent the most direct challenge to human health posed by climate change. Older adults are particularly vulnerable, especially those with common age-associated chronic health conditions (e.g., cardiovascular disease, hypertension, obesity, type 2 diabetes, chronic kidney disease). In parallel, the global population is aging and age-associated disease rates are on the rise. Impairments in the physiological responses tasked with maintaining homeostasis during heat exposure have long been thought to contribute to increased risk of health disorders in older adults during heatwaves. As such, a comprehensive overview of the provisional links between age-related physiological dysfunction and elevated risk of heat-related injury in older adults would be of great value to healthcare officials and policy makers concerned with protecting heat-vulnerable sectors of the population from the adverse health impacts of heatwaves. In this narrative review, we therefore summarize our current understanding of the physiological mechanisms by which aging impairs the regulation of body temperature, hemodynamic stability and hydration status. We then examine how these impairments may contribute to acute pathophysiological events common during heatwaves (e.g., heatstroke, major adverse cardiovascular events, acute kidney injury) and discuss how age-associated chronic health conditions may exacerbate those impairments. Finally, we briefly consider the importance of physiological research in the development of climate-health programs aimed at protecting heat-vulnerable individuals.

Renin-angiotensin aldosterone inhibitor use at hospital discharge among patients with moderate to severe acute kidney injury and its association with recurrent acute kidney injury and mortality

Recurrent episodes of acute kidney injury (AKI) are common among AKI survivors. Renin-angiotensin aldosterone inhibitors (RAASi) are often indicated for these patients but may increase the risk for recurrent AKI. Here, we examined whether RAASi associates with a higher risk for recurrent AKI and mortality among survivors of moderate to severe AKI in a retrospective cohort of Veterans who survived Stage II or III AKI. The primary exposure was RAASi at hospital discharge and the primary endpoint was recurrent AKI within 12 months. Cox proportional hazards models were fit on a propensity score-weighted cohort to compare time to recurrent AKI and mortality by RAASi exposure. Among 96,983 patients, 40% were on RAASi at discharge. Compared to patients who continued RAASi use, those discontinuing use experienced no difference in risk for recurrent AKI but had a significantly higher risk of mortality [hazard ratio 1.33 (95% confidence interval1.26-1.41)]. No differences in recurrent AKI risk was observed for non-users started or not on RAASi compared to prevalent users who continued RAASi. Subgroup analyses among those with diabetes, chronic kidney disease, heart failure, and malignancy were similar with exception of a modest reduction in recurrent AKI risk among RAASi discontinuers with chronic kidney disease. Thus, RAASi use among survivors of moderate to severe AKI was associated with little to no difference in risk for recurrent AKI but was associated with improved survival. Reinitiating or starting RAASi among patients with strong indications is warranted but should be balanced with individual overall risk for recurrent AKI and with adequate monitoring.

Impact of 6% balanced hydroxyethyl starch following cardiopulmonary bypass on renal function: a retrospective study

Background

We aimed to evaluate the effect of limited volume of hydroxyethyl starch (HES) administration on postoperative renal function in patients undergoing cardiac surgery under cardiopulmonary bypass (CPB).

Methods

One thousand six hundred fifty-seven patients undergoing cardiac surgery under CPB over two years were included. The patients were divided according to the amount of HES administrated during the first 2 days post-surgery; moderate dose HES (≥20 ml/kg) versus low dose HES (< 20 ml/kg). Outcomes were compared by using inverse probability weighting.

Results

Incidence of acute kidney injury (AKI) was higher in the moderate HES group (p = .02). However, new renal replacement therapy (RRT) (P = .30) and early mortality (p = .97) was similar between the groups. When adjusted, the moderate HES use was associated with AKI (OR, 1.66; 95% CI, 1.12–2.44; p = .01), but did not increase the risk of new RRT (OR, 1.27; 95% CI, 0.71–2.18; p = .40) or early mortality (HR, 0.73; 95% CI, 0.29–1.81; p = .50).

Conclusions

The moderate dose administration of HES (≥20 ml/kg) in the postoperative period following cardiac surgery might be associated with the risk of AKI. However, it was not associated with serious adverse outcomes such as new RRT or mortality. Further randomized controlled studies are needed to validate study results.

Delayed Implantation of Pumped Kidneys Decreases Renal Allograft Futility in Combined Liver-Kidney Transplantation

BACKGROUND

Combined liver-kidney transplantation (CLKT) improves survival for liver transplant recipients with renal dysfunction; however, the tenuous perioperative hemodynamic and metabolic milieu in high-acuity CLKT recipients increases delayed graft function and kidney allograft failure. We sought to analyze whether delayed KT through pumping would improve kidney outcomes following CLKT.

METHODS

A retrospective analysis (University of California Los Angeles [n = 145], Houston Methodist Hospital [n = 79]) was performed in all adults receiving CLKT at 2 high-volume transplant centers from February 2004 to January 2017, and recipients were analyzed for patient and allograft survival as well as renal outcomes following CLKT.

RESULTS

A total of 63 patients (28.1%) underwent delayed implantation of pumped kidneys during CLKT (dCLKT) and 161 patients (71.9%) received early implantation of nonpumped kidneys during CLKT (eCLKT). Most recipients were high-acuity with median biologic model of end-stage liver disease (MELD) score of, 35 for dCLKT and 34 for eCLKT (P = ns). Pretransplant, dCLKT had longer intensive care unit stay, were more often intubated, and had greater vasopressor use. Despite this, dCLKT exhibited improved 1-, 3-, and 5-year patient and kidney survival (P = 0.02) and decreased length of stay (P = 0.001), kidney allograft failure (P = 0.012), and dialysis duration (P = 0.031). This reduced kidney allograft futility (death or continued need for hemodialysis within 3 mo posttransplant) for dCLKT (6.3%) compared with eCLKT (19.9%) (P = 0.013).

CONCLUSIONS

Delayed implantation of pumped kidneys is associated with improved patient and renal allograft survival and decreased hospital length of stay despite longer kidney cold ischemia. These data should inform the ethical debate as to the futility of performing CLKT in high-acuity recipients.

Sodium Intake and Chronic Kidney Disease

In Chronic Kidney Disease (CKD) patients, elevated blood pressure (BP) is a frequent finding and is traditionally considered a direct consequence of their sodium sensitivity. Indeed, sodium and fluid retention, causing hypervolemia, leads to the development of hypertension in CKD. On the other hand, in non-dialysis CKD patients, salt restriction reduces BP levels and enhances anti-proteinuric effect of renin-angiotensin-aldosterone system inhibitors in non-dialysis CKD patients. However, studies on the long-term effect of low salt diet (LSD) on cardio-renal prognosis showed controversial findings. The negative results might be the consequence of measurement bias (spot urine and/or single measurement), reverse epidemiology, as well as poor adherence to diet. In end-stage kidney disease (ESKD), dialysis remains the only effective means to remove dietary sodium intake. The mismatch between intake and removal of sodium leads to fluid overload, hypertension and left ventricular hypertrophy, therefore worsening the prognosis of ESKD patients. This imposes the implementation of a LSD in these patients, irrespective of the lack of trials proving the efficacy of this measure in these patients. LSD is, therefore, a rational and basic tool to correct fluid overload and hypertension in all CKD stages. The implementation of LSD should be personalized, similarly to diuretic treatment, keeping into account the volume status and true burden of hypertension evaluated by ambulatory BP monitoring.

Comparison of Hilar Clamping Techniques in Partial Nephrectomy: Is Artery Only Clamping Beneficial?

Hilar clamping is widely adopted in open partial nephrectomy, which is a treatment option for small renal cancer to reduce blood loss and improve surgical exposure, but whether to clamp either only artery or both artery and vein remains controversial. The purpose of this study is to determine whether artery only (AO) clamping is more beneficial than en bloc clamping by comparing perioperative variables in patients who underwent partial nephrectomy with either AO clamping or en bloc clamping. Eighty-eight patients with T1 renal tumor who underwent open partial nephrectomy with either AO or en bloc clamping between 2015 and 2018 at our institution were enrolled. They were randomly divided into two groups: AO group (n = 43) and artery and vein (AV) group (n = 45). Renal function was evaluated by serum creatinine (SCr) and differential renal function as determined by mercaptoacetyltriglycine renogram. AO clamping was associated with less total renal functional decrease until postoperative 7th day (P < 0.05). After postoperative 15th day, however, there was no significant difference in total renal functional impairment between AO and AV groups. There was also no significant difference in differential renal function change. Furthermore, AO clamping caused more blood loss and hemoglobin (Hb) decrease than en bloc clamping (P < 0.05). AO clamping is no more beneficial than en bloc clamping in partial nephrectomy, presenting with not significantly better long-term postoperative renal function than en bloc clamping.

Change in renal function associated with drug treatment in heart failure: national guidance

Inhibitors of the renin–angiotensin–aldosterone (RAAS) system are cornerstones of the management of patients with heart failure with reduced left ventricular ejection fraction (HFrEF). However, RAAS inhibitors may cause decline in renal function and/or hyperkalaemia, particularly during initiation and titration, intercurrent illness and during worsening of heart failure. There is very little evidence from clinical trials to guide the management of renal dysfunction. The Renal Association and British Society for Heart Failure have collaborated to describe the interactions between heart failure, RAAS inhibitors and renal dysfunction and give clear guidance on the use of RAAS inhibitors in patients with HFrEF. During initiation and titration of RAAS inhibitors, testing renal function is mandatory; a decline in renal function of 30% or more can be acceptable. During intercurrent illness, there is no evidence that stopping RAAS inhibitor is beneficial, but if potassium rises above 6.0 mmol/L, or creatinine rises more than 30%, RAAS inhibitors should be temporarily withheld. In patients with fluid retention, high doses of diuretic are needed and a decline in renal function is not an indication to reduce diuretic dose: if the patient remains congested, more diuretics are required. If a patient is hypovolaemic, diuretics should be stopped or withheld temporarily. Towards end of life, consider stopping RAAS inhibitors. RAAS inhibition has no known prognostic benefit in heart failure with preserved ejection fraction. Efforts should be made to initiate, titrate and maintain patients with HFrEF on RAAS inhibitor treatment, whether during intercurrent illness or worsening heart failure.

Vasopressor Therapy and Blood Pressure Management in the Setting of Acute Kidney Injury

Acute kidney injury (AKI) is common in the setting of shock. Hemodynamic instability is a risk factor for the development of AKI, and pathophysiological mechanisms include loss of renal perfusion pressure and impaired microcirculation. Although restoration of mean arterial pressure (MAP) may mitigate the risk of AKI to some extent, evidence on this is conflicting. Also debatable is the optimal blood pressure needed to minimize the risk of kidney injury. A MAP of 65 mm Hg traditionally has been considered adequate to maintain renal perfusion pressure, and studies have failed to consistently show improved outcomes at higher levels of MAP. Therapeutic options to support renal perfusion consist of catecholamines, vasopressin, and angiotensin II. Although catecholamines are the most studied, they are associated with adverse events at higher doses, including AKI. Vasopressin and angiotensin II are noncatecholamine options to support blood pressure and may improve microcirculatory hemodynamics through unique mechanisms, including differential vasoconstriction of efferent and afferent arterioles within the nephron. Future areas of study include methods by which clinicians can measure renal blood flow in a macrocirculatory and microcirculatory way, a personalized approach to blood pressure management in septic shock using patient-specific measures of perfusion adequacy, and novel agents that may improve the microcirculation within the kidneys without causing adverse microcirculatory effects in other organs.

The effect of maintaining high hemoglobin levels on long-term kidney function in kidney transplant recipients: a randomized controlled trial

Background

Posttransplant anemia may be a major determinant of chronic allograft nephropathy. However, the impact of correcting anemia on graft function remains controversial.

Methods

A 3-year follow-up of an open-label, multicenter, randomized controlled trial involving kidney transplantation recipients examined whether sustained maintenance of target hemoglobin (Hb) concentrations at a high level (12.5–13.5 g/dL, n = 64) with either darbepoetin alfa or epoetin beta pegol would slow the graft function decline rate as the primary efficacy endpoint, compared with maintenance of a low Hb concentration (10.5–11.5 g/dL, n = 63).

Results

The mean blood pressures in the two groups were well controlled throughout the study. In the high Hb group, mean Hb concentrations increased to >12 g/dL at 3 months, reaching the target range at 18 months. At the end of this study (36 months), the mean Hb concentration was 12.8 ± 0.7 g/dL in the high Hb group and 11.5 ± 1.2 g/dL in the low Hb group. The decline rate of the estimated glomerular filtration (eGFR) rate was considerably greater in the low Hb group (ΔeGFR, −5.1 ± 9.5 mL/min/1.73 m²) than in the high Hb group (−1.0 ± 8.4 mL/min/1.73 m²) (P = 0.02). Of note, only a few high Hb patients developed cardiovascular events and returned to hemodialysis, but the low Hb patients did not.

Conclusion

This prospective study suggests that correcting anemia to the target Hb level range (12.5–13.5 g/dL) slows renal function deterioration by >3 years in the chronic phase of allograft nephropathy.

Impact of concomitant peripheral artery disease on contrast-induced acute kidney injury and mortality in patients with acute coronary syndrome after percutaneous coronary intervention

Subclinical peripheral artery disease (PAD) might be associated with pathophysiology of contrast-induced acute kidney injury (CI-AKI). We hypothesized that concomitant PAD in patients with the acute coronary syndrome (ACS) would represent a high-risk subgroup with a greater incidence of CI-AKI, both of which lead to higher mortality after percutaneous coronary intervention (PCI). Six hundred and seventy-five consecutive patients with ACS who underwent PCI and examination of ankle-brachial index (ABI) were analyzed retrospectively. The presence of PAD was defined as an ABI < 0.9. We investigated whether (1) PAD was an independent predictor of CI-AKI (≥ 0.3 mg/dL or ≥ 50% relative increase in serum creatinine within 48 h after PCI) and (2) PAD and CI-AKI were independently associated with long-term mortality. Of the 675 patients with ACS, 114 (17%) exhibited PAD. The incidence of CI-AKI was significantly higher in PAD patients, compared with the remaining patients (12% vs. 4%, p < 0.001). Multivariate logistic regression analysis revealed that the presence of PAD was an independent predictor for the development of CI-AKI [odds ratio 2.50, 95% confidence interval (CI) 1.07-5.73, p < 0.05]. During the median 4-year follow-up, there were 65 incidents of all-cause death. In the multivariate Cox proportional hazard regression analysis, the presence of PAD [hazard ratio (HR) 2.08, 95% CI 1.17-3.65, p < 0.05] and CI-AKI (HR 2.23, 95% CI 1.08-4.26, p < 0.05) were associated with an increased risk of all-cause mortality. Assessment of ABI provides useful information for predicting CI-AKI and long-term mortality in patients with ACS after PCI.

Comparison of pancreatic and renal blood flow in a canine tachycardia-induced cardiomyopathy model

The pancreas is believed to be vulnerable to hypoperfusion. In dogs with acute pancreatitis, pancreatic ischemia due to heart failure can worsen the condition. However, changes in pancreatic blood flow associated with decreased cardiac function have not been previously studied in dogs. Therefore, we aimed to identify and compare changes in pancreatic versus renal blood flow as a result of cardiac dysfunction. Seven dogs were subjected to rapid ventricular pacing to create heart failure models. Noninvasive blood pressure measurement, ultrasonic cardiography, contrast-enhanced ultrasonography for pancreatic blood flow measurement, and para-aminohippuric acid clearance for renal blood flow measurement were performed before starting and at 2 and 4 weeks after starting the pacing. Left ventricular cardiac output and mean blood pressure decreased at 2 and 4 weeks after starting the pacing, and pancreatic blood flow decreased at 2 and 4 weeks after starting the pacing. However, renal blood flow did not change at 2 weeks but decreased 4 weeks after starting the pacing. Overall, this study demonstrated that reduced pancreatic blood flow due to cardiac dysfunction occurs, similar to renal blood flow. This suggests that decreased pancreatic blood flow is not unusual and may frequently occur in dogs with heart failure. The results of this study support the speculation that heart failure can exacerbate acute pancreatitis. Additionally, this study provides useful basic information for designing further studies to study this association.

Predictors of Acute Kidney Injury After Hip Fracture in Older Adults

INTRODUCTION

This study aimed to investigate the prevalence of acute kidney injury (AKI) following hip fracture surgery in geriatric patients and to identify predictors for development of AKI with a focus on possible preventable risk factors.

METHODS

In this retrospective cohort study, we reviewed electronic medical records of all patients above 65 years of age who underwent hip fracture surgery at Copenhagen University Hospital, Bispebjerg, Denmark, in 2018. Acute kidney injury was assessed according to the Kidney Disease Improving Global Outcomes guidelines. Multivariate logistic regression analyses were used to identify independent risk factors for AKI.

RESULTS

Postoperative AKI developed in 28.4% of the included patients (85/299). Acute kidney injury was associated with increased length of admission (11.3 vs 8.7 days, P < .001) and 30-day mortality (18/85 vs 16/214, P = .001). In multivariable analysis, higher age (odds ratio [OR]: 1.05, 95% confidence interval [CI]: 1.01-1.08, P = .004), heart disease (OR: 1.78, 95% CI: 1.01-3.11, P = .045), and postoperative blood transfusion (OR: 1.84, 95% CI: 1.01-3.36, P = .048) were associated with AKI. Moreover, a higher postoperative C-reactive protein (199.0 ± 99.9 in patients with AKI, 161.3 ± 75.2 in patients without AKI) and lower postoperative diastolic blood pressure were observed in patients developing AKI.

DISCUSSION AND CONCLUSION

Acute kidney injury was common following hip fracture surgery and associated with longer admissions and increased mortality. Patients developing AKI were older and showed several postoperative similarities, including higher C-reactive protein, lower postoperative diastolic pressure, and the need for blood transfusion.

Perioperative Acute Kidney Injury

Perioperative organ injury is among the leading causes of morbidity and mortality of surgical patients. Among different types of perioperative organ injury, acute kidney injury occurs particularly frequently and has an exceptionally detrimental effect on surgical outcomes. Currently, acute kidney injury is most commonly diagnosed by assessing increases in serum creatinine concentration or decreased urine output. Recently, novel biomarkers have become a focus of translational research for improving timely detection and prognosis for acute kidney injury. However, specificity and timing of biomarker release continue to present challenges to their integration into existing diagnostic regimens. Despite many clinical trials using various pharmacologic or nonpharmacologic interventions, reliable means to prevent or reverse acute kidney injury are still lacking. Nevertheless, several recent randomized multicenter trials provide new insights into renal replacement strategies, composition of intravenous fluid replacement, goal-directed fluid therapy, or remote ischemic preconditioning in their impact on perioperative acute kidney injury. This review provides an update on the latest progress toward the understanding of disease mechanism, diagnosis, and managing perioperative acute kidney injury, as well as highlights areas of ongoing research efforts for preventing and treating acute kidney injury in surgical patients.

Preoperative platelet count, preoperative hemoglobin concentration and deep hypothermic circulatory arrest duration are risk factors for acute kidney injury after pulmonary endarterectomy: a retrospective cohort study

Background

Acute kidney injury (AKI) is a major postoperative morbidity of patients undergoing cardiac surgery and has a negative effect on prognosis. The kidney outcomes after pulmonary endarterectomy (PEA) have not yet been reported; However, several perioperative characteristics of PEA may induce postoperative AKI. The objective of our study was to identify the incidence and risk factors for postoperative AKI and its association with short-term outcomes.

Methods

This was a single-center, retrospective, observational, cohort study. Assessments of AKI diagnosis was executed based on the Kidney Disease Improving Global Outcomes (KDIGO) criteria.

Results

A total of 123 consecutive patients who underwent PEA between 2014 and 2018 were included.

The incidence of postoperative AKI was 45% in the study population. Stage 3 AKI was associated with worse short-term outcomes and 90-day mortality (p < 0.001, p = 0.002, respectively). The independent predictors of postoperative AKI were the preoperative platelet count (OR 0.992; 95%CI 0.984–0.999; P = 0.022), preoperative hemoglobin concentration (OR 0.969; 95%CI 0.946–0.993; P = 0.01) and deep hypothermic circulatory arrest (DHCA) time (OR 1.197; 95%CI 1.052–1.362; P = 0.006) in the multivariate analysis.

Conclusion

The incidence of postoperative AKI was relatively high after PEA compared with other types of cardiothoracic surgeries. The preoperative platelet count, preoperative hemoglobin concentration and DHCA duration were modifiable predictors of AKI, and patients may benefit from some low-risk, low-cost perioperative measures.

Estimating the risk of acute kidney injury associated with use of diuretics and renin angiotensin aldosterone system inhibitors: A population based cohort study using the clinical practice research datalink

Background

The risk of acute kidney injury (AKI) attributable to renin angiotensin aldosterone (RAAS) inhibitors and diuretics remains unclear.

Methods

We conducted a prospective cohort study using the Clinical Practice Research Datalink (2008–2015) linked to Hospital Episode Statistics – Admitted Patient Care and Office for National Statistics mortality data. Patients were included if they had one or more chronic diagnoses requiring medication. Exposed patients had a first ever prescription for RAAS inhibitors/diuretics during the study period. AKI risk associated with exposure was determined by multivariable Cox regression, propensity score-adjusted Cox regression and a prior event rate ratio (PERR) analysis.

Results

One hundred forty thousand nine hundred fifty-two individuals were included. Increased AKI risk in the exposed group was demonstrated in both the multivariable and propensity score-adjusted cox regressions (HR 1.23 (95% CI 1.04–1.45) and HR 1.24 (1.05–1.47) respectively). The PERR analysis provided a similar overall hazard ratio with a wider confidence interval (HR 1.29 (0.94–1.63)). The increased AKI risk in the exposed group was present only in those receiving two or more antihypertensives. Absolute AKI risk was small.

Conclusions

RAAS inhibitors/diuretics result in an increased risk of AKI. The absolute increase in AKI risk is small, however, and needs to be considered in the context of any potential benefits.

Diabetic kidney disease: New clinical and therapeutic issues. Joint position statement of the Italian Diabetes Society and the Italian Society of Nephrology on "The natural history of diabetic kidney disease and treatment of hyperglycemia in patients with type 2 diabetes and impaired renal function"

AIMS

This joint document of the Italian Diabetes Society and the Italian Society of Nephrology reviews the natural history of diabetic kidney disease (DKD) in the light of the recent epidemiological literature and provides updated recommendations on anti-hyperglycemic treatment with non-insulin agents.

DATA SYNTHESIS

Recent epidemiological studies have disclosed a wide heterogeneity of DKD. In addition to the classical albuminuric phenotype, two new albuminuria-independent phenotypes have emerged, i.e., "nonalbuminuric renal impairment" and "progressive renal decline", suggesting that DKD progression toward end-stage kidney disease (ESKD) may occur through two distinct pathways, albuminuric and nonalbuminuric. Several biomarkers have been associated with decline of estimated glomerular filtration rate (eGFR) independent of albuminuria and other clinical variables, thus possibly improving ESKD prediction. However, the pathogenesis and anatomical correlates of these phenotypes are still unclear. Also the management of hyperglycemia in patients with type 2 diabetes and impaired renal function has profoundly changed during the last two decades. New anti-hyperglycemic drugs, which do not cause hypoglycemia and weight gain and, in some cases, seem to provide cardiorenal protection, have become available for treatment of these individuals. In addition, the lowest eGFR safety thresholds for some of the old agents, particularly metformin and insulin secretagogues, have been reconsidered.

CONCLUSIONS

The heterogeneity in the clinical presentation and course of DKD has important implications for the diagnosis, prognosis, and possibly treatment of this complication. The therapeutic options for patients with type 2 diabetes and impaired renal function have substantially increased, thus allowing a better management of these individuals.

Molecular optical imaging probes for early diagnosis of drug-induced acute kidney injury

Drug-induced acute kidney injury (AKI) with a high morbidity and mortality is poorly diagnosed in hospitals and deficiently evaluated in drug discovery. Here, we report the development of molecular renal probes (MRPs) with high renal clearance efficiency for in vivo optical imaging of drug-induced AKI. MRPs specifically activate their near-infrared fluorescence or chemiluminescence signals towards the prodromal biomarkers of AKI including the superoxide anion, N-acetyl-β-D-glucosaminidase and caspase-3, enabling an example of longitudinal imaging of multiple molecular events in the kidneys of living mice. Importantly, they in situ report the sequential occurrence of oxidative stress, lysosomal damage and cellular apoptosis, which precedes clinical manifestation of AKI (decreased glomerular filtration). Such an active imaging mechanism allows MRPs to non-invasively detect the onset of cisplatin-induced AKI at least 36 h earlier than the existing imaging methods. MRPs can also act as exogenous tracers for optical urinalysis that outperforms typical clinical/preclinical assays, demonstrating their clinical promise for early diagnosis of AKI.

Optimal systolic blood pressure in noncritically ill patients with acute kidney injury: A retrospective cohort study

Background

Few data showed the optimal blood pressure (BP) in noncritically ill patients with acute kidney injury (AKI) relative to mortality or severe AKI. We therefore sought to analyze the data that exist for the ideal target range for BP in noncritically ill patients with AKI.

Methods

We performed a retrospective cohort study involving 1,612 hospitalized patients who were diagnosed with AKI using the Kidney Disease: Improving Global Outcomes definition based on serum creatinine measurements for a period of 1 year. The average systolic BP (SBP) was categorized into 10-mmHg increments (within 48 hours after the development of AKI). The primary outcome was a composite of severe AKI or 90-day mortality.

Results

The composite outcome rate in patients was 18.7% (302/1,612). The relationship between BP and the composite outcome followed a U-shaped curve, with an increased event rate observed at both low and high BP values. The average SBP after AKI predicted the composite outcome after adjusting for baseline variables (reference SBP: 120–129 mmHg; < 100 mmHg: hazard ratio [HR] 1.84, P = 0.015; 100–109 mmHg: HR 1.56, P = 0.038; 110–119 mmHg: HR 1.15, P = 0.483; 130–139 mmHg: HR 1.51, P = 0.045; ≥ 140 mmHg: HR 1.73, P = 0.005).

Conclusion

Among noncritically ill patients with AKI, a U-shaped curve association was observed between the average SBP within 48 hours after AKI and the composite primary outcome of this study, with the lowest event rate for SBP ranging from approximately 110 to 129 mmHg.

Dynamic Contrast-Enhanced Ultrasound Identifies Microcirculatory Alterations in Sepsis-Induced Acute Kidney Injury

OBJECTIVES

We developed quantitative methods to analyze microbubble kinetics based on renal contrast-enhanced ultrasound imaging combined with measurements of sublingual microcirculation on a fixed area to quantify early microvascular alterations in sepsis-induced acute kidney injury.

DESIGN

Prospective controlled animal experiment study.

SETTING

Hospital-affiliated animal research institution.

SUBJECTS

Fifteen female pigs.

INTERVENTIONS

The animals were instrumented with a renal artery flow probe after surgically exposing the kidney. Nine animals were given IV infusion of lipopolysaccharide to induce septic shock, and six were used as controls.

MEASUREMENTS AND MAIN RESULTS

Contrast-enhanced ultrasound imaging was performed on the kidney before, during, and after having induced shock. Sublingual microcirculation was measured continuously using the Cytocam on the same spot. Contrast-enhanced ultrasound effectively allowed us to develop new analytical methods to measure dynamic variations in renal microvascular perfusion during shock and resuscitation. Renal microvascular hypoperfusion was quantified by decreased peak enhancement and an increased ratio of the final plateau intensity to peak enhancement. Reduced intrarenal blood flow could be estimated by measuring the microbubble transit times between the interlobar arteries and capillary vessels in the renal cortex. Sublingual microcirculation measured using the Cytocam in a fixed area showed decreased functional capillary density associated with plugged sublingual capillary vessels that persisted during and after fluid resuscitation.

CONCLUSIONS

In our lipopolysaccharide model, with resuscitation targeted at blood pressure, contrast-enhanced ultrasound imaging can identify renal microvascular alterations by showing prolonged contrast enhancement in microcirculation during shock, worsened by resuscitation with fluids. Concomitant analysis of sublingual microcirculation mirrored those observed in the renal microcirculation.

Study of kidney morphologic and structural changes related to different ischemia times and types of clamping of the renal vascular pedicle

Purpose

This study aimed to study morphological and renal structural changes in relation to different ischemic times and types of renal vascular pedicle clamping.

Methods

Sixteen pigs were divided into two groups (n = 8): Group AV - unilateral clamping of the renal artery and vein and Group A - unilateral clamping of the renal artery only, both with the contralateral kidney used as control. Serial biopsies were performed at 0, 10, 20, 30, 40, 50, 60, 70, 80, and 90 minutes after clamping.

Results

there is a correlation between the occurrence of renal damage as a function of time (p <0.001), with a higher frequency of Group A lesions for cellular alterations (vascular congestion and edema, interstitial inflammatory infiltrate, interstitial hemorrhage and cell degeneration), with the exception of in the formation of pigmented cylinders that were evidenced only in the AV Group.

Conclusion

the number of lesions derived from ischemia is associated with the duration of the insult, there is a significant difference between the types of clamping, and the AV Group presented a lower frequency of injuries than Group A. The safety time found for Group A was 10 minutes and for Group AV 20 minutes.

Outcomes in Patients with Vasodilatory Shock and Renal Replacement Therapy Treated with Intravenous Angiotensin II

Supplemental Digital Content is available in the text.

Objective:

Acute kidney injury requiring renal replacement therapy in severe vasodilatory shock is associated with an unfavorable prognosis. Angiotensin II treatment may help these patients by potentially restoring renal function without decreasing intrarenal oxygenation. We analyzed the impact of angiotensin II on the outcomes of acute kidney injury requiring renal replacement therapy.

Design:

Post hoc analysis of the Angiotensin II for the Treatment of High-Output Shock 3 trial.

Setting:

ICUs.

Patients:

Patients with acute kidney injury treated with renal replacement therapy at initiation of angiotensin II or placebo (n = 45 and n = 60, respectively).

Interventions:

IV angiotensin II or placebo.

Measurements and Main Results:

Primary end point: survival through day 28; secondary outcomes included renal recovery through day 7 and increase in mean arterial pressure from baseline of ≥ 10 mm Hg or increase to ≥ 75 mm Hg at hour 3. Survival rates through day 28 were 53% (95% CI, 38%–67%) and 30% (95% CI, 19%–41%) in patients treated with angiotensin II and placebo (p = 0.012), respectively. By day 7, 38% (95% CI, 25%–54%) of angiotensin II patients discontinued RRT versus 15% (95% CI, 8%–27%) placebo (p = 0.007). Mean arterial pressure response was achieved in 53% (95% CI, 38%–68%) and 22% (95% CI, 12%–34%) of patients treated with angiotensin II and placebo (p = 0.001), respectively.

Conclusions:

In patients with acute kidney injury requiring renal replacement therapy at study drug initiation, 28-day survival and mean arterial pressure response were higher, and rate of renal replacement therapy liberation was greater in the angiotensin II group versus the placebo group. These findings suggest that patients with vasodilatory shock and acute kidney injury requiring renal replacement therapy may preferentially benefit from angiotensin II.

New mouse model of chronic kidney disease transitioned from ischemic acute kidney injury

Acute kidney injury (AKI) significantly increases the risk of development of chronic kidney disease (CKD), which is closely associated with the severity of AKI. However, the underlying mechanisms for the AKI to CKD transition remain unclear. Several animal models with AKI to CKD transition have been generated and widely used in research; however, none of them exhibit the typical changes in glomerular filtration rate or plasma creatinine, the hallmarks of CKD. In the present study, we developed a novel model with a typical phenotype of AKI to CKD transition in C57BL/6 mice. In this model, life-threatening ischemia-reperfusion injury was performed in one kidney, whereas the contralateral kidney was kept intact to maintain animal survival; then, after 2 wk of recovery, when the renal function of the injured kidney restored above the survival threshold, the contralateral intact kidney was removed. Animals of this two-stage unilateral ischemia-reperfusion injury model with pedicle clamping of 21 and 24 min exhibited an incomplete recovery from AKI and subsequent progression of CKD with characteristics of a progressive decline in glomerular filtration rate, increase in plasma creatinine, worsening of proteinuria, and deleterious histopathological changes, including interstitial fibrosis and glomerulosclerosis. In conclusion, a new model of the AKI to CKD transition was generated in C57BL/6 mice.

Protective effect of piperine in ischemia-reperfusion induced acute kidney injury through inhibition of inflammation and oxidative stress

Background and aim

Renal ischemia-reperfusion is associated with inflammation and oxidative stress. As a major compound in black pepper, piperine has anti-inflammatory and anti-oxidative properties. In present study, the protective effects of oral administration of piperine in renal ischemia-reperfusion (IR) induced acute kidney injuries (AKI) were investigated.

Experimental procedure

Male Wistar rats received piperine (10 or 20 mg/kg.bw) or vehicle for 10 days. The artery and vein of both kidneys were then clamped for 30 min, followed by a 24-h reperfusion period. Concentrations of creatinine and urea-nitrogen in descending aorta blood were measured, and malondialdehyde (MDA) and ferric reducing/antioxidant power (FRAP) levels were measured in kidney tissue to evaluate the oxidative stress. Inflammation was evaluated by measuring the TNF-α and ICAM-1 mRNA expression levels in renal cortical tissue using Real Time PCR method and counting leukocytes infiltration to interstitium. Further measured were tissue damages in H & E stained sections.

Results

Renal IR reduced FRAP, while increasing the plasma concentrations of creatinine and urea-nitrogen, tissue MDA level, TNF-α and ICAM-1 mRNA expressions, leukocyte infiltration and histopathologic injuries. Piperine administration significantly reduced the plasma concentrations of creatinine and urea-nitrogen, expression of pro-inflammatory factors, oxidative stress and renal histopathologic injuries. It is to be noted that 20 mg/kg dose was more effective.

Conclusion

Our results suggest piperine protects the kidney against ischemia-reperfusion induced acute kidney injuries by its anti-inflammatory and anti-oxidative properties.

•

Renal ischemia-reperfusion increased the inflammation and oxidative stress parameters.

•

Ischemia-reperfusion increased histopathological damages and functional parameters.

•

Piperine pretreatment significantly reduced the inflammation and oxidative stress.

•

Piperine administration ameliorated renal function and histopathologic damages.

Prediction of Acute Glomerular Filtration Rate Reductions Following Renin-angiotensin System Blockade in Chronic Kidney Disease: A Possible Application of Ultrasonography in Clinical Practice

Objective Renal arteriolosclerosis is a risk factor for acute reductions in the glomerular filtration rate (GFR) when renin-angiotensin system (RAS) inhibitors are administered. Renal arteriolosclerosis can be detected by an increase in the resistive index (RI) on Doppler ultrasonography. The purpose of the present study is to determine whether or not the RI can predict acute GFR reductions following RAS blockade in chronic kidney disease (CKD). Methods We surveyed all CKD patients who were hospitalized in Otemae Hospital from January 2008 to December 2017. One hundred and eight patients who had been newly treated with RAS inhibitors were able to be followed for 14 weeks. The end point was an acute reduction in the GFR, defined as a decrease of ≥30%. Results Twenty-three of the 108 patients presented with acute GFR reductions. The cumulative probability of acute GFR reductions was 3.3% and 53% in patients with RI ≤0.70 and RI >0.70, respectively (p<0.001). A univariate Cox proportional-hazards analysis showed that the RI, age, GFR, systolic blood pressure, urinary protein excretion, diabetic kidney disease, coronary artery disease, and use of diuretics were significant variables. Multivariate hazard ratios were calculated from the RI and three established variables (age, GFR, diuretics), and the RI and use of diuretics were shown to be significant risk factors for acute GFR reductions. Conclusion These results suggest that an increase in the RI, as well as the use of diuretics, may be risk factors for acute GFR reductions following RAS blockade.

"I don't get no respect": the role of chloride in acute kidney injury

Acute kidney injury (AKI) is a major public health problem that complicates 10-40% of hospital admissions. Importantly, AKI is independently associated with increased risk of progression to chronic kidney disease, end-stage renal disease, cardiovascular events, and increased risk of in-hospital and long-term mortality. The chloride content of intravenous fluid has garnered much attention over the last decade, as well as its association with excess use and adverse outcomes, including AKI. Numerous studies show that changes in serum chloride concentration, independent of serum sodium and bicarbonate, are associated with increased risk of AKI, morbidity, and mortality. This comprehensive review details the complex renal physiology regarding the role of chloride in regulating renal blood flow, glomerular filtration rate, tubuloglomerular feedback, and tubular injury, as well as the findings of clinical research related to the chloride content of intravenous fluids, changes in serum chloride concentration, and AKI. Chloride is underappreciated in both physiology and pathophysiology. Although the exact mechanism is debated, avoidance of excessive chloride administration is a reasonable treatment option for all patients and especially in those at risk for AKI. Therefore, high-risk patients and those with "incipient" AKI should receive balanced solutions rather than normal saline to minimize the risk of AKI.

Effect of high- versus low-volume saline administration on acute kidney injury after cardiac surgery

Background

Fluid resuscitation is critical to perioperative maintenance of adequate preload and cardiac output after cardiac surgery. Liberal use of saline, however, is reportedly associated with an increased risk of acute kidney injury (AKI) in critically ill patients. This study examined the effects of high- versus low-volume saline administration on AKI after cardiac surgery.

Methods

In this retrospective study, we evaluated 1,740 consecutive patients who underwent cardiac surgery over a 2-year period. The patients were divided into high-volume saline (n=328, 18.8%) and low-volume saline (n=1,412, 81.2%) groups based on the amount of saline (>1 or ≤1 L, respectively) administered during the first 48 postoperative hours.

Results

AKI, the primary outcome, was defined according to the Risk, Injury, Failure, Loss, End Stage classification. There were no significant differences in the incidence of AKI (P=0.46), new renal replacement therapy (RRT) (P=0.39), and early mortality (P=0.52) between the 2 groups. Adjustment of baseline characteristics using propensity score matching showed that high-volume of saline administration was not significantly associated with an increased risk of AKI (OR, 1.22; 95% CI, 0.77-1.93; P=0.38), new RRT (OR, 1.25; 95% CI, 0.68-2.28; P=0.45), or early mortality (HR, 0.98; 95% CI, 0.48-2.02; P=0.97). These results were validated by further adjustments for significant covariates.

Conclusions

High-volume administration of saline in the period following cardiac surgery was not associated with a significant increase in the risk of AKI.

Determining Fractional Urate Excretion Rates in Hyponatremic Conditions and Improved Methods to Distinguish Cerebral/Renal Salt Wasting From the Syndrome of Inappropriate Secretion of Antidiuretic Hormone

Our evaluation of hyponatremic patients is in a state of confusion because the assessment of the volume status of the patient and determinations of urine sodium concentrations (UNa) >30–40 mEq/L have dominated our approach despite documented evidence of many shortcomings. Central to this confusion is our inability to differentiate cerebral/renal salt wasting (C/RSW) from the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), syndromes with diametrically opposing therapeutic goals. The recent proposal to treat most or all hyponatremic patients makes differentiation even more important and reports of C/RSW occurring without cerebral disease leads to a clinically important proposal to change cerebral to renal salt wasting (RSW). Differentiating SIADH from RSW is difficult because of identical clinical parameters that characterize both syndromes. Determination of fractional urate excretion (FEurate) is central to a new algorithm, which has proven to be superior to current methods. We utilized this algorithm and differences in physiologic response to isotonic saline infusions between SIADH and RSW to evaluate hyponatremic patients from the general medical wards of the hospital. In 62 hyponatremic patients, 17 (27%) had SIADH, 19 (31%) had reset osmostat (RO), 24 (38%) had RSW, 1 due to HCTZ and 1 Addison's disease. Interestingly, 21 of 24 with RSW had no evidence of cerebral disease and 10 of 24 with RSW had UNa < 20 mEqL. We conclude that 1. RSW is much more common than is perceived, 2.the term cerebral salt wasting should be changed to RSW 3. RO should be eliminated as a subclass of SIADH, 4. SIADH should be redefined 5. The volume approach is ineffective and 6. There are limitations to determining UNa, plasma renin, aldosterone or atrial/brain natriuretic peptides. We also present data on a natriuretic peptide found in sera of patients with RSW and Alzheimer's disease.