The Supporting Role of Combined and Sequential Extracorporeal Blood Purification Therapies in COVID-19 Patients in Intensive Care Unit

Critical clinical forms of COVID-19 infection often include Acute Kidney Injury (AKI), requiring kidney replacement therapy (KRT) in up to 20% of patients, further worsening the outcome of the disease. No specific medical therapies are available for the treatment of COVID-19, while supportive care remains the standard treatment with the control of systemic inflammation playing a pivotal role, avoiding the disease progression and improving organ function. Extracorporeal blood purification (EBP) has been proposed for cytokines removal in sepsis and could be beneficial in COVID-19, preventing the cytokines release syndrome (CRS) and providing Extra-corporeal organ support (ECOS) in critical patients. Different EBP procedures for COVID-19 patients have been proposed including hemoperfusion (HP) on sorbent, continuous kidney replacement therapy (CRRT) with adsorbing capacity, or the use of high cut-off (HCO) membranes. Depending on the local experience, the multidisciplinary capabilities, the hardware, and the available devices, EBP can be combined sequentially or in parallel. The purpose of this paper is to illustrate how to perform EBPs, providing practical support to extracorporeal therapies in COVID-19 patients with AKI.

Impact of different hemodiafiltration solutions on ionemia in long-term CRRT

Critical patients with Acute Kidney Injury (AKI) requiring renal replacement therapy are in most cases eligible only for continuous modalities where the electrolyte balance control is a critical issue. The standard solutions used for hemodiafiltration, containing potassium at 2 mmol/L and no phosphorus, determines during the extended renal replacement therapy hypokalemia and hypophosphatemia. Therefore, solutions containing potassium and phosphate in physiological concentrations were formulated to avoid electrolyte imbalances and reduce ion alterations in prolonged treatments, these solutions are not routinely used in the standard clinical practice. To avoid electrolyte imbalances, we have first introduced in our practice two different solutions and then we have retrospectively analyzed the electrolyte balance upon these two solutions in order to identity the impact of these solutions on potassium and phosphate according to our clinical practice. We retrospectively analyzed 96 patients treated with Continuous Renal Replacement Therapy (CRRT) in the intensive care units (ICU) at Padua's University Hospital to evaluate the role on electrolyte balance of Phoxilium^® and Prismasol 2^® that differ in their composition and the need for electrolytes infusions. In the Phoxilium group the frequency of hypokalemia, hypophosphatemia, and the need of potassium and phosphate replacement were significantly reduced resulting in a reduction in complications, workload, and clinical risk associated with infusions of electrolytes. Our data demonstrated that the use of these two different hemodiafiltration solutions can reduce the occurrence of hypokalemia and hypophosphatemia during CRRT performing personalized treatments without the use of potassium and phosphate infusions.

Impact of hemoperfusion with polymyxin B added to hemofiltration in patients with endotoxic shock: a case-control study

Background

Septic shock is a leading cause of death in critical patients. In patients with gram-negative septic shock, hemoperfusion with polymyxin B aims to remove endotoxins from plasma. We analyzed the clinical and biological response to hemoperfusion in patients with septic shock and acute kidney injury.

Methods

This prospective case–control study in the medical–surgical intensive care unit of a university hospital included consecutive adults patients with septic shock and suspected gram-negative bacteria infection with elevated plasma endotoxin activity (EAA > 0.6 EU/ml) and acute kidney injury requiring continuous renal replacement therapy (CRRT). At onset of septic shock, half underwent CRRT plus hemoperfusion with polymyxin B for two hours a day during two consecutive days (hemoperfusion group) and half received only CRRT (control group). We measured clinical, physiological, and biological parameters (EAA, C-reactive protein, procalcitonin, and cytokines) daily during the first 5 days.

Results

We included 18 patients (male, 33%; mean age, 67.5; mean SOFA score, 11.3). Abdominal infections predominated (50% had peritonitis). At the beginning of CRRT, RIFLE classification was “failure” for 72% and “injury” for 28%. Baseline characteristics did not differ between groups. Patients in the hemoperfusion group required longer mechanical ventilation (12.4 vs. 9.4 days, p = 0.03) and CRRT (8.5 vs. 6 days, p = 0.01) than in the control group. Noradrenaline doses, lactate, procalcitonin, and C-reactive protein decreased in both groups. At day 5, EAA was significantly lower in the hemoperfusion group (0.58 EU/ml vs. 0.73 EU/ml in controls, p = 0.03). There were no significant differences between groups in other biomarkers or ICU mortality (33.3% in the treatment group vs. 44.4% in the control group, p = 0.5). No adverse effects of hemoperfusion were observed.

Conclusions

Hemoperfusion with polymyxin B added to CRRT resulted in faster decrease in endotoxin levels, but we observed no improvements in clinical, physiological, or biological parameters.

Electronic supplementary material

The online version of this article (10.1186/s13613-018-0465-8) contains supplementary material, which is available to authorized users.

Differences in acute kidney injury ascertainment for clinical and preclinical studies

Background

Acute kidney injury (AKI) is a common clinical condition directly associated with adverse outcomes. Several AKI biomarkers have been discovered, but their use in clinical and preclinical studies has not been well examined. This study aims to investigate the differences between clinical and preclinical studies on AKI biomarkers.

Methods

We performed a systematic review of clinical and preclinical interventional studies that considered AKI biomarkers in enrollment criteria and/or outcome assessment and described the main differences according to their setting, the inclusion of biomarkers in the definition of AKI and the use of biomarkers as primary or secondary end points.

Results

In the 151 included studies (76 clinical, 75 preclinical), clinical studies have prevalently focused on cardiac surgery (38.1%) and contrast-associated AKI (17.1%), while the majority of preclinical studies have focused on ether ischemia-reperfusion injury or drug-induced AKI (42.6% each). A total of 57.8% of clinical studies defined AKI using the standard criteria and only 19.7% of these studies used AKI biomarkers in the definition of renal injury. Conversely, the majority of preclinical studies defined AKI according to the increase in serum creatinine and blood urea nitrogen, and 32% included biomarkers in that definition. The percentage of both clinical and preclinical studies with biomarkers as a primary end point has not significantly increased in the last 10 years; however, preclinical studies are more likely to use AKI biomarkers as a primary end point compared with clinical studies [odds ratio 2.31 (95% confidence interval 1.17-4.59); P  =  0.016].

Conclusion

Differences between clinical and preclinical studies are evident and may affect the translation of preclinical findings in the clinical setting.

Effects of continuous renal replacement therapy on serum cytokines, neutrophil gelatinase-associated lipocalin, and prognosis in patients with severe acute kidney injury after cardiac surgery

The aim of our study was to evaluate the effect of continuous renal replacement therapy (CRRT) on serum cytokines, neutrophil gelatinase-associated lipocalin (NGAL), and prognosis in patients with severe acute kidney injury (AKI) following cardiac surgery. A total number of 153 patients with severe AKI following cardiac surgery were treated with CRRT. They were divided into the survival and non-survival groups. Clinical data from these two groups before and after CRRT were recorded and analyzed. It was found that the number of impaired organs, MODS and APACHE II scores were significantly higher in the non-survival group than those in the survival group before CRRT. After CRRT, MODS and APACHE II scores decreased significantly. The post-CRRT levels of serum TNF-a and IL-6 were significantly decreased. After CRRT, serum NGAL decreased in the two groups, but the levels were higher in the non-survival group than those in the survival group. MODS and APACHE II scores could be used to evaluate the severity of AKI in patients after cardiac surgery. CRRT is an effective treatment for these patients and high levels of TNF-a, IL-6, and NGAL are associated with a poor prognosis in these patients.

Biomarkers upon discontinuation of renal replacement therapy predict 60-day survival and renal recovery in critically ill patients with acute kidney injury

INTRODUCTION

There is no consensus on the specific indications for weaning critically ill patients with acute kidney injury (AKI) off renal replacement therapy (RRT). This study aimed to explore the prognostic value of several biomarkers measured upon discontinuation of RRT for their value in predicting 60-day survival and renal recovery in an effort to add knowledge to the decision-making process regarding RRT withdrawal.

METHODS

We prospectively enrolled 102 patients with AKI who required RRT from the intensive care unit. Serum osteopontin (sOPN), serum interleukin 6 (sIL-6), serum cystatin C (sCysC), sIL-18, serum neutrophil gelatinase-associated lipocalin and urinary IL-18 and urinary neutrophil gelatinase-associated lipocalin were measured upon discontinuation of RRT. Patients were followed up at 60 days for survival and renal recovery.

FINDINGS

Patients who survived showed lower levels of all serum and urinary biomarkers. Serum OPN (OR 1.029, 95% CI 1.013-1.047, P = 0.001), diabetes (OR 23.157, 95% CI 4.507-118.981, P < 0.001) and APACHE II score (OR 1.308, 95% CI 1.121-1.527, P = 0.001) were independent predictors of 60-day mortality. Patients whose sOPN values fell within the highest and middle tertiles showed 5.25- and 2.31-fold increased risks of mortality, respectively, compared with that of patients in the lowest tertile. The addition of sOPN to the clinical model resulted in significant net reclassification improvement of 0.453 (P = 0.026) and an integrated discriminative index of 0.155 (P = 0.032). Lower levels of sOPN and sIL-6 were associated with greater odds of 60-day survival (AUC 0.812 and 0.741). The AUC value for predicting survival reached its highest level when all biomarkers were combined with urine output (UO) and urinary and serum creatinine upon discontinuation of RRT (0.882). Lower sCysC performed as well as higher UO in predicting 60-day renal recovery with the greatest AUC of 0.743.

DISCUSSION

Upon discontinuation of RRT, serum and urinary biomarkers, particularly sOPN, may predict 60-day survival and renal recovery in critically ill patients with AKI. The serum levels of OPN, IL-6 and CysC may be useful when considering withdrawal of RRT on the basis of conventional indicators.

A Single-Center Randomized Trial of Intraoperative Zero-Balanced Ultrafiltration During Cardiopulmonary Bypass for Patients With Impaired Kidney Function Undergoing Cardiac Surgery

OBJECTIVES

The authors investigated whether zero-balance ultrafiltration (Z-BUF) during bypass significantly improves clinical and cost outcomes or biomarkers of kidney injury for patients with preoperative kidney impairment (estimated glomerular filtration rate [eGFR]<60 mL/minute) undergoing cardiac surgery.

DESIGN

A single-center randomized controlled trial recruited, patients between 2010 and 2013, with a 12-months follow-up.

SETTING

Hospital.

PARTICIPANTS

One hundred ninety-nine patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

INTERVENTIONS

Patients were assigned randomly to receive zero-balance ultrafiltration (Z-BUF) or not, with stratification for degree of kidney dysfunction and diabetes.

MEASUREMENTS AND MAIN RESULTS

The authors assessed clinical efficacy and kidney function biomarkers. Cumulative probability of discharge from the intensive care unit (ICU) was assessed by Kaplan-Meier plots and was found not to be significantly different between the two trial arms (p = 0.61). After adjusting for EuroSCORE, diabetes, eGFR, cardioplegia types and type of surgery in a Cox proportional hazard model, hazard ratios (HR) for ICU length of stay between the Z-BUF and no-Z-BUF groups was not significantly different: HR (95% CI): 0.89 (0.66, 1.20; p = 0.44). In contrast, significant reductions in postoperative chest infections and the composite of clinical endpoints (death, strokes, and myocardial infarctions) in the Z-BUF group were observed. In addition, Z-BUF significantly abrogated the rise in the kidney damage markers urinary NGAL/creatinine ratio, urea, creatinine and eGFR during CPB and adverse events risks.

CONCLUSIONS

Z-BUF during bypass surgery is associated with significant reductions in morbidity and biomarkers of CPB-induced acute kidney injury soon after CPB, which are indicative of clearance of inflammatory/immune mediators from the circulation.

Measuring biomarkers of acute kidney injury during renal replacement therapy: wisdom or folly?

Early data are now appearing relating to the measurement of biomarkers of acute kidney injury during renal replacement therapy. These data go some way in describing the clearance of these molecules during renal support. Understanding the potential clearance, or otherwise, of these proteins may lead to directing our therapies in the future particularly with regard to cessation of renal support. We describe a recent study which has provided data that may aid in addressing this issue.

The plasma level and biomarker value of neutrophil gelatinase-associated lipocalin in critically ill patients with acute kidney injury are not affected by continuous venovenous hemofiltration and anticoagulation applied

Introduction

Neutrophil gelatinase-associated lipocalin (NGAL) is a biomarker of acute kidney injury (AKI), and levels reflect severity of disease in critically ill patients. However, continuous venovenous hemofiltration (CVVH) may affect plasma levels by clearance or release of NGAL by activated neutrophils in the filter, dependent on the anticoagulation regimen applied. We therefore studied handling of NGAL by CVVH in patients with AKI.

Methods

Immediately before initiation of CVVH, prefilter blood was drawn. After 10, 60, 180, and 720 minutes of CVVH, samples were collected from pre- and postfilter (in- and outlet) blood and ultrafiltrate. CVVH with the following anticoagulation regimens was studied: no anticoagulation in case of a high bleeding tendency (n = 13), unfractionated heparin (n = 8), or trisodium citrate (n = 21). NGAL levels were determined with enzyme-linked immunosorbent assay (ELISA).

Results

Concentrations of NGAL at inlet and outlet were similar, and concentrations did not change over time in any of the anticoagulation groups; thus no net removal or production of NGAL occurred. Concentrations of NGAL at inlet correlated with disease severity at initiation of CVVH and at the end of a CVVH run. Concentrations of NGAL in the ultrafiltrate were lower with citrate-based CVVH (P = 0.03) and decreased over time, irrespective of anticoagulation administered (P < 0.001). The sieving coefficient and clearance of NGAL were low and decreased over time (P < 0.001).

Conclusions

The plasma level and biomarker value of NGAL in critically ill patients with AKI are not affected by CVVH, because clearance by the filter was low. Furthermore, no evidence exists for intrafilter release of NGAL by neutrophils, irrespective of the anticoagulation method applied.

[NGAL, biomarker of acute kidney injury in 2012]

Neutrophil Gelatinase Associated Lipocalin (NGAL) is one of the most promising biomarkers for acute kidney injury (AKI). Although urinary NGAL is intuitively more appropriate to apprehend renal injury, clinical data have accumulated on the potential interest of NGAL measured indifferently in serum or urine. Diagnostic performance of NGAL greatly varies across studies according to different factors such as the type of patients (pediatric versus adult) and the clinical situations (surgery versus intensive care). Overall, NGAL is presented as a useful tool to diagnose and predict AKI outcome but several issues (the absence of a unique pertinent threshold value, the incomplete analytical validation of its measurement and, its apparent limited clinical added value as compared to traditional AKI markers) remain to be addressed in order to definitely recommend its use in clinical practice.

Levels of neutrophil gelatinase-associated lipocalin in 2 patients with crush syndrome after a mudslide

Neutrophil gelatinase-associated lipocalin is one of the most promising biomarkers for the diagnosis of acute kidney injury. An increase in the level of neutrophil gelatinase-associated lipocalin is a good predictor of acute kidney injury and is associated with an increase in the serum level of creatinine. Two victims of a mudslide in Messina, Italy, initially had crush syndrome followed by development of acute kidney injury. The development of acute kidney injury is the second most common cause of death after large earthquakes and other natural disasters, but at the same time, crush-related acute kidney injury is one of the few life-threatening complications of crush injuries that can be reversed if diagnosed early and treated. In this case, measuring the level of neutrophil gelatinase-associated lipocalin enabled early diagnosis of acute kidney injury and anticipation of the changes in levels of conventional markers such as creatinine.

New biomarkers for acute renal injury

Incidence of acute kidney injury (AKI) is increasing rapidly to epidemic proportions. Development of AKI, especially in intensive care settings, is associated with increased morbidity, mortality and hospitalization costs. Currently available diagnostic tools are mostly insensitive for early diagnosis, however prompt diagnosis and risk stratification are necessary for guiding therapy and preventing progression of disease. Finding an early, reliable, suitable, easily reproducible, economical and accurate biomarker for AKI is a top research priority. In recent years, many urinary and serum proteins have been investigated as possible early markers of AKI and some of them have shown great promise. This topic reviews some of the emerging biomarkers of AKI.