Routine assessment of kidney urea clearance, dialysis dose and protein catabolic rate in the once-weekly haemodialysis regimen.

BACKGROUND: The dialysis dose (Kt/V) and normalized protein catabolic rate (PCRn) are the most useful indices derived from the urea kinetic model (UKM) in haemodialysis (HD) patients. The kidney urea clearance (Kru) is another important UKM parameter which plays a key role in the prescription of incremental HD. Ideally, the three kinetic parameters should be assessed using the complex software Solute Solver based on the double pool UKM. In the clinical setting, however, the three indices are estimated with simplified formulae. The recently introduced software SPEEDY assembles the aforementioned equations in a plain spreadsheet, to produce quite accurate results of Kru, Kt/V and PCRn. Unfortunately, specific equations to compute Kt/V and PCRn for patients on a once-weekly HD regimen (1HD/wk) were not available at the time SPEEDY was built-up. We devised a new version of SPEEDY (SPEEDY-1) and an even simpler variant (SPEEDY-1S), using two recently published equations for the 1HD/wk schedule . Moreover, we also added a published equation to estimate the equivalent renal clearance (EKR) normalized to urea distribution volume (V) of 35 L (EKR35) from Kru and Kt/V . Aim of the present study was to compare the results obtained using the new methods (SPEEDY-1 and SPEEDY-1S) with those provided by the reference method Solute Solver. SUBJECTS AND METHODS: One hundred historical patients being treated with the once-weekly HD regimen were enrolled. A total of 500 HD sessions associated to the availability of monthly UKM studies were analysed in order to obtain Kru, single pool Kt/V (spKt/V), equilibrated Kt/V (eKt/V), V, PCRn and EKR35 values by using Solute Solver, SPEEDY-1 and SPEEDY-1S. RESULTS: When comparing the paired values of the above UKM parameters, as computed by SPEEDY-1 and Solute Solver, respectively, all differences but one were statistically significant at the one-sample t-test; however, the agreement limits at Bland-Altman analysis showed that all differences were negligible. When comparing the paired values of the above UKM parameters, as computed by SPEEDY-1S and Solute Solver, respectively, all differences were statistically significant; however, the agreement limits showed that the differences were negligible as far as Kru, spKt/V and eKt/V are concerned, though much larger regarding V, PCRn and EKR35. CONCLUSIONS: We implemented SPEEDY with a new version specific for the once-weekly HD regimen, SPEEDY-1. It provides accurate results and is presently the best alternative to Solute Solver. Using SPEEDY-1S led to a larger difference in PCRn and EKR35, which could be acceptable for clinical practice if SPEEDY-1 is not available.

High convection volume in online post-dilution haemodiafiltration: relevance, safety and costs.

Increasing evidence suggests that treatment with online post-dilution haemodiafiltration (HDF) improves clinical outcome in patients with end-stage kidney disease, if compared with haemodialysis (HD). Although the primary analyses of three large randomized controlled trials (RCTs) showed inconclusive results, post hoc analyses of these and previous observational studies comparing online post-dilution HDF with HD showed that the risk of overall and cardiovascular mortality is lowest in patients who are treated with high-volume HDF. As such, the magnitude of the convection volume seems crucial and can be considered as the 'dose' of HDF. In this narrative review, the relevance of high convection volume in online post-dilution HDF is discussed. In addition, we briefly touch upon some safety and cost issues.

Preoperative assessment and planning of haemodialysis vascular access.

Effective haemodialysis (HD) requires a reliable vascular access (VA). Clinical practice guidelines strongly recommend the arteriovenous fistula (AVF) as the preferred VA in HD patients. The creation of an AVF should be promoted in all eligible patients who choose HD, as it improves outcomes and reduces costs when compared with central venous catheters. Fistula eligibility is a 'work in progress'. Three steps in order to increase the pool of eligible patients can be individualized: (i) process of care, which includes three fundamental items: the VA team, early VA education and timely VA surgery referral; (ii) preoperative evaluation; (iii) surgical strategy. Nephrologists should be able to play a leading and coordinating role of the VA team. They should design a plan that identifies a sequence of options that can be used to provide adequate renal replacement therapy throughout the life span of every end-stage renal disease patient. The main points of this strategy are (i) early vascular education, in which a 'save the vein program' should always be implemented; (ii) timely VA surgery referral and preoperative evaluation: careful examination of arterial and venous beds is mandatory before VA placement; physical examination in addition to colour Doppler ultrasound mapping improves AVF outcomes; (iii) surgical strategy: a successful VA strategy must take into account vascular anatomy, clinical factors and prognosis.

The long-term prognosis of acute kidney injury: acute renal failure as a cause of chronic kidney disease.

There is a widespread opinion that acute kidney injury (AKI) is a rather harmless complication and that survival is determined not by renal dysfunction per se, but by the severity of the underlying disease. This opinion is in sharp contrast to evidence from several recent experimental and clinical investigations indicating that AKI is a condition which exerts a fundamental impact on the course of the disease, the evolution of associated complications and on prognosis, independently from the type and severity of the underlying condition. In conclusion, severe AKI in the critically ill patient is associated with high rates of morbidity, mortality and consumption of health care resources.