Renal functional reserve (RFR) represents the capacity of the kidney to increase glomerular filtration rate (GFR) in response to certain physiological or pathological stimuli or conditions. Once baseline GFR is determined, RFR can be assessed clinically after an oral protein load or intravenous amino acid infusion. In clinical practice, baseline GFR displays variable levels due to diet or other factors. RFR is the difference between peak ‘stress' GFR induced by the test (p.o. or i.v.) and the baseline GFR. In clinical scenarios where hyperfiltration is present (high baseline GFR due to pregnancy, hypertension or diabetic nephropathy, in solitary kidney or kidney donors), RFR may be fully or partially used to achieve normal or supranormal renal function. Since commonly used renal function markers, such as GFR, may remain within normal ranges until 50% of nephrons are lost or in patients with a single remnant kidney, the RFR test may represent a sensitive and early way to assess the functional decline in the kidney. RFR assessment may become an important tool to evaluate the ability of the kidney to recover completely or partially after a kidney attack. In case of healing with a defect and progressive fibrosis, recovery may appear complete clinically, but a reduced RFR may be a sign of a maladaptive repair or subclinical loss of renal mass. Thus, a reduction in RFR may represent the equivalent of renal frailty or susceptibility to insults. The main aim of this article is to review the concept of RFR, its utility in different clinical scenarios, and future perspective for its use.

During the last decade, blood purification therapies have been proposed as an effective therapy to control the cytokines dysregulation in systemic inflammatory syndromes. Among them, the treatment with high cut-off membranes is characterized by larger pore size and more effective clearance for middle molecular weight molecules (cytokines). In this paper, we performed a thoughtful review of the literature on HCO being used for blood purification indications in all systemic inflammation syndromes. Clinical and experimental studies show that the use of high effluent flows in a pure diffusive treatment effectively removes serum cytokines with a safe profile in albumin clearance. In clinical studies, the removal of these inflammatory mediators is associated with a significant improvement in hemodynamic condition, oxygenation indices, and organ dysfunction. © 2014 S. Karger AG, Basel

Background: Refractory congestive heart failure (RCHF) is associated with a high mortality rate and is a major contributor to hospital admissions. Peritoneal dialysis (PD) is an option to control volume overload and perhaps improve outcomes in this challenging patient population. The aim of this systematic review is to describe the relative risk-benefit ratio based on data reported regarding the use of PD in RCHF. This study was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. An electronic search of PubMed, Embase, and the Cochrane Library was performed to identify relevant studies published from January 1951 to February 2014. Eligible studies selected were prospective or retrospective adult population studies on PD in the setting of RCHF. The following clinical outcomes were used to assess PD therapy: (1) hospitalization rates; (2) heart function; (3) renal function; (4) fluid overload, and (5) adverse clinical outcomes. Summary: Of 864 citations, we excluded 843 citations and included 21 studies (n = 673 patients). After PD, hospitalization days declined significantly (p = 0.0001), and heart function improved significantly (left ventricular ejection fraction: p = 0.0013; New York Heart Association classification: p = 0.0000). There were no statistically significant differences in glomerular filtration rate after PD treatment in non-chronic kidney disease stage 5D patients (p = 0.1065). Among patients treated with PD, body weight decreased significantly (p = 0.0006). The yearly average peritonitis rate was 14.5%, and the average yearly mortality was 20.3%. Key Messages: This systematic review suggests that PD may be an effective and safe therapeutic tool for patients with RCHF.

Among elective cardiac surgical patients with normal resting glomerular filtration rates, preoperative RFR was highly predictive of AKI. A reduced RFR appears to be a novel risk factor for AKI, and measurement of RFR preoperatively can identify patients who are likely to benefit from preventive measures or to select for use of biomarkers for early detection. Larger prospective studies to validate the use of RFR in strategies to prevent AKI are warranted. ClinicalTrials.gov identifier: NCT03092947, ISRCTN Registry: ISRCTN16109759.