Long-term sequelae of acute kidney injury in the ICU:

Soluble Programmed Cell Death Protein 1 and Its Ligand: Potential Biomarkers to Predict Acute Kidney Injury After Surgery in Critically Ill Patients

Purpose

Programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) have been detected in injury kidney. However, their expressions are unclear in mice kidneys under renal ischemia-reperfusion injury (IRI). In this study, we would observe the expressions of PD-1 and PD-L1 in kidney tissues and analyze the association between the concentrations of PD-1 and PD-L1 in mouse kidney homogenate and the corresponding concentrations of soluble PD-1 (sPD-1) and soluble PD-L1 (sPD-L1) in plasma after renal IRI. Further, we explored the predictive value of sPD-1 and sPD-L1 for acute kidney injury (AKI) in high-risk patients after surgery.

Methods

This study established an AKI model induced by IRI in mice. Plasma, kidney samples, and homogenate were collected 0h, 24h, and 48h after surgery for immunohistochemistry and enzyme-linked immunosorbent assay. Then, we continuously enrolled 88 AKI high-risk patients who underwent noncardiac surgery. The biomarkers, including sPD-1, sPD-L1, and urine neutrophil gelatinase-associated lipocalin (NGAL), tissue inhibitor of metalloproteinase-2 (TIMP-2), insulin-like growth factor-binding protein 7 (IGFBP7), were detected immediately after surgery.

Results

Our data revealed the concentrations of PD-1 and PD-L1 in kidney homogenate, and sPD-1 and sPD-L1 in plasma significantly increased at 0h, 24h, and 48h after IRI. A positive association was found between PD-1 and sPD-1 (r = 0.774, p < 0.001), and between PD-L1 and sPD-L1 (r = 0.881, p < 0.001). Compared to NGAL, [TIMP-2]*[IGFBP7], sPD-1 and sPD-L1 showed better predictive abilities for AKI with an area under the ROC curve of 0.856 (95% confidence interval [CI]: 0.825-0.958, p < 0.001) and 0.906 (95% CI: 0.764-0.921, p < 0.001).

Conclusion

The increased expressions of PD-1 and PD-L1 in kidneys under IRI suggested they may play essential roles in AKI development. sPD-1 and sPD-L1 can indirectly reflect the expressions of PD-1 and PD-L1 in kidneys, respectively. sPD-1 and sPD-L1 showed excellent predictive ability for AKI in high-risk patients.

Plasma osteopontin levels in patients with acute kidney injury requiring dialysis: a study in a tertiary care institute in South India

PURPOSE

Osteopontin (OPN) is evolving as a novel biomarker of injury, overall survival and renal outcome in critically ill patients with acute kidney injury (AKI), requiring renal replacement therapy.

METHODS

We performed a prospective study on 35 consecutive patients of acute kidney injury requiring renal replacement therapy (AKIN stage 3). OPN levels were measured in the patients and in the controls. The relation between OPN and the severity of illness and its effect on the AKI and renal outcome were studied.

RESULTS

There was a statistically significant elevation of OPN in patients of AKIN stage 3 in comparison to healthy controls (p = 0.001). The Sequential Organ Function Assessment (SOFA) scores were found to be higher in septic group in comparison to non-septic group and it was statistically significant (p = 0.014). There was significant correlation between SOFA scoring and OPN levels suggesting its association with severity (r = 0.382, p = 0.023).

CONCLUSIONS

In our study, OPN was found to be a valuable marker of severity of injury, its association with sepsis and renal recovery, in patients with acute kidney injury needing renal replacement therapy.

Sickle cell disease: Clinical presentation and management of a global health challenge

Sickle cell disease is an autosomal recessive, multisystem disorder, characterised by chronic haemolytic anaemia, painful episodes of vaso-occlusion, progressive organ failure and a reduced life expectancy. Sickle cell disease is the most common monogenetic disease, with millions affected worldwide. In well-resourced countries, comprehensive care programs have increased life expectancy of sickle cell disease patients, with almost all infants surviving into adulthood. Therapeutic options for sickle cell disease patients are however, still scarce. Predictors of sickle cell disease severity and a better understanding of pathophysiology and (epi)genetic modifiers are warranted and could lead to more precise management and treatment. This review provides an extensive summary of the pathophysiology and management of sickle cell disease and encompasses the characteristics, complications and current and future treatment options of the disease.

Association of Urinary Neutrophil Gelatinase-Associated Lipocalin With Long-Term Renal Outcomes in ICU Survivors: A Retrospective Observational Cohort Study

BACKGROUND

Epidemiological studies recently suggested that acute kidney injury (AKI) in intensive care units (ICUs) increases the risk of chronic kidney disease development and progression. However, whether any AKI biomarker can predict long-term renal outcomes in ICU survivors remains unclear. This study was undertaken to elucidate the role of urinary biomarkers for long-term renal outcome prediction after ICU discharge.

METHODS

This retrospective observational study examined 495 adult patients who had been admitted to the ICU of the University of Tokyo Hospital. Major adverse kidney events (MAKE): death, incident end-stage renal disease (ESRD), and halving of estimated glomerular filtration rate (eGFR), at hospital discharge and long-term renal outcomes of 30% reduction of eGFR or incident ESRD were evaluated.

RESULTS

Among all the enrolled 495 patients, 393 patients were discharged from the hospital without MAKE. Data of eGFR up to two years after ICU discharge were available for 173 patients; 63 patients (36.4%) were positive for long-term renal outcomes. Step-wise logistic regression analysis demonstrated that male sex and urinary neutrophil gelatinase-associated lipocalin (NGAL) measured at ICU admission showed significant associations with long-term renal outcomes. Receiver operating characteristic curve analysis showed the area under the curve of 0.66 (95% confidence interval 0.57-0.74) for prediction of long-term renal outcome by urinary NGAL.

CONCLUSION

Urinary NGAL measured at ICU admission was significantly associated with long-term renal outcomes after hospital discharge in MAKE-free ICU survivors. Urinary NGAL measurements at ICU might be useful to identify a high risk population of kidney disease progression after intensive care.

Response to different furosemide doses predicts AKI progression in ICU patients with elevated plasma NGAL levels

BACKGROUND

Furosemide responsiveness (FR) is determined by urine output after furosemide administration and has recently been evaluated as a furosemide stress test (FST) for predicting severe acute kidney injury (AKI) progression. Although a standardized furosemide dose is required for FST, variable dosing is typically employed based on illness severity, including renal dysfunction in the clinical setting. This study aimed to evaluate whether FR with different furosemide doses can predict AKI progression. We further evaluated the combination of an AKI biomarker, plasma neutrophil gelatinase-associated lipocalin (NGAL), and FR for predicting AKI progression.

RESULTS

We retrospectively analyzed 95 patients who were treated with bolus furosemide in our medical-surgical intensive care unit. Patients who had already developed AKI stage 3 were excluded. A total of 18 patients developed AKI stage 3 within 1 week. Receiver operating curve analysis revealed that the area under the curve (AUC) values of FR and plasma NGAL were 0.87 (0.73-0.94) and 0.80 (0.67-0.88) for AKI progression, respectively. When plasma NGAL level was < 142 ng/mL, only one patient developed stage 3 AKI, indicating that plasma NGAL measurements were sufficient to predict AKI progression. We further evaluated the performance of FR in 51 patients with plasma NGAL levels > 142 ng/mL. FR was associated with AUC of 0.84 (0.67-0.94) for AKI progression in this population with high NGAL levels.

CONCLUSIONS

Although different variable doses of furosemide were administered, FR revealed favorable efficacy for predicting AKI progression even in patients with high plasma NGAL levels. This suggests that a combination of FR and biomarkers can stratify the risk of AKI progression in a clinical setting.

Long-term renal and overall survival of critically ill patients with acute renal injury who received continuous renal replacement therapy

BACKGROUND

Acute kidney injury (AKI) is associated with the increased short-term mortality of critically ill patients on continuous renal replacement therapy (CRRT). The aim of this research was to evaluate the association of kidney function at discharge with the long-term renal and overall survival of critically ill patients with AKI who were on CRRT in an intensive care unit (ICU).

METHODS

We retrospectively collected data for critically ill patients with AKI who were admitted to ICU on CRRT at a tertiary metropolitan hospital in China between 2008 and 2013. The patients were followed up to their death or to 30 September 2016 by telephone.

RESULTS

A total of 403 patients were enrolled in this study. The 1-, 3- and 5-year patient survival rates were 64.3 ± 2.4, 55.8 ± 2.5 and 46.3 ± 2.7%, respectively. In multivariate analysis, age, sepsis, decreased renal perfusion (including volume contraction, congestive heart failure, hypotension and cardiac arrest), preexisting kidney disease, Apache II score, Saps II score, vasopressors and eGFR <45 mL/min/1.73 m2 at discharge were independent factors for worse long-term patient survival. And age, preexisting kidney disease, Apache II score, mechanical ventilation (MV) and eGFR <45 mL/min/1.73 m2 at discharge were also associated with worse renal survival.

CONCLUSIONS

This study showed that impaired kidney function at discharge was shown to be an important risk factor affecting the long-term renal survival rates of critically ill patients with AKI. An eGFR <45 mL/min/1.73 m2 was an independent risk factor for decreased overall survival and renal survival.

Acute kidney injury during a pediatric sickle cell vaso-occlusive pain crisis

BACKGROUND

Patients who develop sickle cell disease (SCD) nephropathy are at a high risk for mortality. The pathophysiology of vaso-occlusive pain crisis may contribute to acute kidney injury (AKI). Non-steroidal anti-inflammatory drugs, known inducers of AKI, are used to treat pain crises. Multiple gaps exist in the knowledge about the impact of AKI in SCD.

METHODS

We conducted a 2-year retrospective review of AKI events in patients admitted for vaso-occlusive crisis. AKI was defined by an increase of ≥0.3 mg/dL or 50% in serum creatinine from baseline. Laboratory values and ketorolac administration by days and dose (mg/kg) were identified from hospital records. A generalized mixed effects model for binary outcomes evaluated AKI based on laboratory variables and ketorolac administration. A generalized mixed Poisson effects model analyzed the association of AKI with hospital length of stay.

RESULTS

Thirty-three out of 197 admissions for vaso-occlusive pain crisis (17%) were associated with AKI. Fifty-two percent of the cases presented to the Emergency Room (ER) with AKI. Every one unit decrease in hemoglobin from baseline to admission increased the risk of AKI by 49%. Among patients who received ketorolac for pain, both total days and doses of ketorolac were associated with AKI. Finally, patients with pain and AKI required longer periods of hospitalization than patients without AKI.

CONCLUSION

Acute kidney injury during sickle cell pain crisis is common and may be an important modifiable risk factor for developing chronic kidney disease (CKD). Further studies are needed to determine the impact of nephrotoxic medications on progressive SCD nephropathy.

Two-year follow-up of patients with septic shock presenting with low HDL: the effect upon acute kidney injury, death and estimated glomerular filtration rate

BACKGROUND

Sepsis is associated with decreased levels of high-density lipoprotein (HDL) cholesterol. HDL has anti-inflammatory properties, and the use of Apo A-I mimetic peptides is associated with renal function improvement in animal models of sepsis. However, it is not known whether decreased HDL level results in impaired renal function in human sepsis. We investigated whether low levels of HDL conferred an increased risk of sepsis-associated acute kidney injury (AKI) or long-term decreased estimated glomerular filtration rate (eGFR) after sepsis.

METHODS

HDL concentration (mg dL^-1 ) was measured in plasma samples from 180 patients with septic shock at admission to the Emergency Department (ED). We divided the patients using median HDL as a cut-off value and assessed the frequency of sepsis-associated AKI and long-term decreased eGFR after sepsis. Univariate and multivariate analyses were performed.

RESULTS

Patients with low HDL had a significantly greater frequency of KDIGO 2 or 3 sepsis-associated AKI [39/90 (43.3%) vs. 12/90 (13.3%), P < 0.001] and decreased long-term eGFR [24/58 (41.4%) vs. 11/57 (19.3%), P = 0.018] compared to those with high HDL. The adjusted OR for sepsis-associated AKI and decreased eGFR after sepsis in the lower HDL group was 2.80 (95% CI 1.08-7.25, P = 0.033) and 5.45 (95% CI 1.57-18.93, P = 0.008), respectively.

CONCLUSION

Low HDL levels during sepsis are associated with increased risk of sepsis-associated AKI, and/or subsequent decreased eGFR. These results suggest that HDL may be involved and/or may be a marker of kidney injury during and after sepsis.

Erythropoietin concentration in acute kidney injury is associated with insulin-like growth factor-binding protein-1

AIM

Erythropoietin (EPO) production is stimulated by hypoxia in the kidney. Ischaemic injury plays a crucial role in the pathogenesis of acute kidney injury (AKI). However, EPO concentrations in critically ill patients complicated with AKI have not been evaluated sufficiently. This study was conducted to clarify the factors associated with plasma EPO concentrations in AKI.

METHODS

This study prospectively enrolled 98 critically ill adult patients treated at the adult mixed ICU. Plasma EPO, insulin-like growth factor-binding protein-1 (IGFBP-1), neutrophil gelatinase-associated lipocalin (NGAL), interleukin-6 (IL-6) and urinary N-acetyl-β-D-glucosaminidase (NAG) were measured on ICU admission.

RESULTS

Acute kidney injury occurred in 42 (42.9%) patients. Significantly higher plasma EPO in the AKI group was detected than in the non-AKI group (16.13 (9.87-28.47) mIU/mL versus 27.81 (10.16-106.02) mIU/mL, P < 0.05). Plasma IGFBP-1 in the AKI group was also significantly higher than in the non-AKI group (19 208 (8820-50 780) pg/mL versus 63 199 (25 289-147 489) pg/mL, P < 0.05). Plasma EPO concentration was negatively correlated with haemoglobin in the non-AKI group with statistical significance, but not in the AKI group. Multiple logistic regression analysis revealed that plasma EPO in the AKI group was associated significantly with plasma IGFBP-1 and complication of diabetes mellitus, but not the haemoglobin concentration, partial pressure of arterial oxygen (PaO2 ), and IL-6.

CONCLUSIONS

Not low arterial oxygen tension, haemoglobin concentration, and inflammation evaluated by IL-6 but plasma IGFBP-1 was significantly associated with plasma EPO concentration in AKI, suggesting an unknown mechanism related to systemic stress conditions for EPO regulation in AKI.

Recovery from AKI in the critically ill: potential confounders in the evaluation

PURPOSE

Studies on recovery from acute kidney injury (AKI) in ICU patients yield variable results. We assessed the impact of different recovery definitions, of different exclusion criteria, and of imputing missing baseline creatinine on AKI recovery in a heterogeneous ICU population.

METHODS

Secondary analysis of the EPaNIC database. Recovery of kidney function in patients who developed AKI in ICU was assessed at hospital discharge. We studied recovery rates of different AKI stages with different definitions of recovery after inclusion or exclusion of non-survivors and in patients with or without chronic kidney disease (CKD). In addition, the impact of imputing missing baseline creatinine was investigated.

RESULTS

A total of 1310 AKI patients were studied of which 977 were discharged alive from hospital. Rate of complete recovery (absence of KDIGO criteria) was markedly higher in survivors than in all AKI patients (79.5 vs 67.0%), especially for more severe forms of AKI. For patients with CKD, only the need for renal replacement therapy worsened kidney outcome as compared with no-CKD patients. Using stricter definitions of complete recovery significantly reduced its occurrence. New or worsening CKD occurred in 30% of AKI survivors. In no-CKD patients with available baseline creatinine, using an imputed baseline did not affect recovery. Patients with unavailable baseline creatinine were different from those with known baseline and revealed different recovery patterns.

CONCLUSION

These results indicate the need for rigorous description of AKI severity, the included population, definitions, and baseline creatinine handling in reports on AKI recovery.

Long-term sequelae of severe acute kidney injury in the critically ill patient without comorbidity: a retrospective cohort study

BACKGROUND AND OBJECTIVES

Acute kidney injury (AKI) necessitating renal replacement therapy (RRT) is associated with high mortality and increased risk for end stage renal disease. However, it is unknown if this applies to patients with a preliminary unremarkable medical history. The purpose of this study was to describe overall and renal survival in critically ill patients with AKI necessitating RRT stratified by the presence of comorbidity.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

A retrospective cohort study was performed, between 1994 and 2010, including all adult critically ill patients with AKI necessitating RRT, stratified by the presence of comorbidity. Logistic regression, survival curve and cox proportional hazards analyses were used to evaluate overall and renal survival. Standardized mortality rate (SMR) analysis was performed to compare long-term survival to the predicted survival in the Dutch population.

RESULTS

Of the 1067 patients included only 96(9.0%) had no comorbidity. Hospital mortality was 56.6% versus 43.8% in patients with and without comorbidity, respectively. In those who survived hospitalization 10-year survival was 45.0% and 86.0%, respectively. Adjusted for age, sex and year of treatment, absence of comorbidity was not associated with hospital mortality (OR=0.74, 95%-CI=0.47-1.15), while absence of comorbidity was associated with better long-term survival (adjusted HR=0.28, 95%-CI = 0.14-0.58). Compared to the Dutch population, patients without comorbidity had a similar mortality risk (SMR=1.6, 95%-CI=0.7-3.2), while this was increased in patients with comorbidity (SMR=4.8, 95%-CI=4.1-5.5). Regarding chronic dialysis dependency, 10-year renal survival rates were 76.0% and 92.9% in patients with and without comorbidity, respectively. Absence of comorbidity was associated with better renal survival (adjusted HR=0.24, 95%-CI=0.07-0.76).

CONCLUSIONS

While hospital mortality remains excessively high, the absence of comorbidity in critically ill patients with RRT-requiring AKI is associated with a relative good long-term prognosis in those who survive hospitalization.

The relationship of intravenous fluid chloride content to kidney function in patients with severe sepsis or septic shock

BACKGROUND

Previous studies suggest a relationship between chloride-rich intravenous fluids and acute kidney injury in critically ill patients.

OBJECTIVES

The aim of this study was to evaluate the relationship of intravenous fluid chloride content to kidney function in patients with severe sepsis or septic shock.

METHODS

A retrospective chart review was performed to determine (1) quantity and type of bolus intravenous fluids, (2) serum creatinine (Cr) at presentation and upon discharge, and (3) need for emergent hemodialysis (HD) or renal replacement therapy (RRT). Linear regression was used for continuous outcomes, and logistic regression was used for binary outcomes and results were controlled for initial Cr. The primary outcome was change in Cr from admission to discharge. Secondary outcomes were need for HD/RRT, length of stay (LOS), mortality, and organ dysfunction.

RESULTS

There were 95 patients included in the final analysis; 48% (46) of patients presented with acute kidney injury, 8% (8) required first-time HD or RRT, 61% (58) were culture positive, 55% (52) were in shock, and overall mortality was 20% (19). There was no significant relationship between quantity of chloride administered in the first 24 hours with change in Cr (β = -0.0001, t = -0.86, R(2) = 0.92, P = .39), need for HD or RRT (odds ratio [OR] = 0.999; 95% confidence interval [CI], 0.999-1.000; P = .77), LOS >14 days (OR = 1.000; 95% CI, 0.999-1.000; P = .68), mortality (OR = 0.999; 95% CI, 0.999-1.000; P = .88), or any type of organ dysfunction.

CONCLUSION

Chloride administered in the first 24 hours did not influence kidney function in this cohort with severe sepsis or septic shock.

Continuous renal replacement therapy with regional citrate anticoagulation: do we really know the details?

PURPOSE OF REVIEW

A significant proportion of critically ill patients with acute kidney injury require continuous renal replacement therapy (CRRT). This article summarizes current evidence on the diagnosis and treatment of acute kidney injury. Regional citrate anticoagulation (RCA) is an emerging but complex technique. A variety of solutions and systems are currently used for RCA. Descriptions of the dosage and methods differ significantly and may cause confusion in everyday practice. This article reviews important scientific findings and highlights pharmacological and pathophysiological aspects of RCA, with a special emphasis on practical clinical issues regarding dosage and available citrate solutions.

RECENT FINDINGS

RCA provides a similar or even longer circuit run, with manageable metabolic complications. Although large-scale multicentre trials are needed, there is increasing evidence for the benefits of citrate solutions in CRRT. International guidelines recommend using citrate anticoagulation rather than heparin in patients without contraindications against citrate.

SUMMARY

RCA-CRRT is a technique that can be safely used in the majority of intensive care patients with severe multiple-organ failure. The range of citrate solutions available, the different methods in use--continuous venovenous haemofiltration, continuous venovenous haemodialysis and continuous venovenous haemodiafiltration--and the lack of a generally accepted complete CRRT 'set' have impeded implementation of the technique in clinical practice. Unresolved questions regarding dosage and assessment preclude evidence-based comparison in prospective, multicentre studies. For the moment, each institution has to develop a local working protocol. In clinical practice, detailed staff training and monitoring of possible metabolic disturbances for this complex intervention is essential.

In nonagenarians, acute kidney injury predicts in-hospital mortality, while heart failure predicts hospital length of stay

BACKGROUND/AIMS

The elderly constitute an increasing proportion of admitted patients worldwide. We investigate the determinants of hospital length of stay and outcomes in patients aged 90 years and older.

METHODS

We retrospectively analyzed all admitted patients aged >90 years from the general medical wards in a tertiary referral medical center between August 31, 2009 and August 31, 2012. Patients' clinical characteristics, admission diagnosis, concomitant illnesses at admission, and discharge diagnosis were collected. Each patient was followed until discharge or death. Multivariate logistic regression analysis was utilized to study factors associated with longer hospital length of stay (>7 days) and in-hospital mortality.

RESULTS

A total of 283 nonagenarian in-patients were recruited, with 118 (41.7%) hospitalized longer than one week. Nonagenarians admitted with pneumonia (p = 0.04) and those with lower Barthel Index (p = 0.012) were more likely to be hospitalized longer than one week. Multivariate logistic regression analysis revealed that patients with lower Barthel Index (odds ratio [OR] 0.98; p = 0.021) and those with heart failure (OR 3.05; p = 0.046) had hospital stays >7 days, while patients with lower Barthel Index (OR 0.93; p = 0.005), main admission nephrologic diagnosis (OR 4.83; p = 0.016) or acute kidney injury (OR 30.7; p = 0.007) had higher in-hospital mortality.

CONCLUSION

In nonagenarians, presence of heart failure at admission was associated with longer hospital length of stay, while acute kidney injury at admission predicted higher hospitalization mortality. Poorer functional status was associated with both prolonged admission and higher in-hospital mortality.

Renal oxygenation and haemodynamics in acute kidney injury and chronic kidney disease

Acute kidney injury (AKI) is a major burden on health systems and may arise from multiple initiating insults, including ischaemia-reperfusion injury, cardiovascular surgery, radiocontrast administration and sepsis. Similarly, the incidence and prevalence of chronic kidney disease (CKD) continues to increase, with significant morbidity and mortality. Moreover, an increasing number of AKI patients survive to develop CKD and end-stage renal disease. Although the mechanisms for the development of AKI and progression to CKD remain poorly understood, initial impairment of oxygen balance likely constitutes a common pathway, causing renal tissue hypoxia and ATP starvation that, in turn, induce extracellular matrix production, collagen deposition and fibrosis. Thus, possible future strategies for one or both conditions may involve dopamine, loop diuretics, atrial natriuretic peptide and inhibitors of inducible nitric oxide synthase, substances that target kidney oxygen consumption and regulators of renal oxygenation, such as nitric oxide and heme oxygenase-1.

The promise of immune cell therapy for acute kidney injury

Acute kidney injury (AKI) often results from ischemia reperfusion, sepsis, or exposure to nephrotoxins and is associated with a high rate of mortality and morbidity. Advances in understanding the pathophysiology of AKI may lead to the development of specific therapies. Although there is evidence of an important role for immune cells in AKI, the specific relevant populations and the mechanisms of their actions are unclear. In this issue of the JCI, Li et al. demonstrate that adenosine manipulates DC responses to kidney injury, raising hope that immunotherapy could be a tangible approach to AKI.