Effects of Reduced Intradialytic Urea Generation Rate and Residual Renal Clearance on Modeled Urea Distribution Volume andKt/Vin Conventional, Daily, and Nocturnal Dialysis

Are dialysis adequacy indices independent of solute generation rate?

KT/V is by definition independent of solute generation rate. Alternative dialysis adequacy indices (DAIs) such as equivalent renal clearance (EKR), standard KT/V (stdKT/V), and solute removal index (SRI) are estimated as the ratio of solute mass removed to an average solute mass in the body or solute concentration in blood; both nominator and denominator in these formulas depend on the solute generation rate. Our objective was to investigate whether and under which conditions the alternative DAIs are independent of solute generation rate. By using general compartment modeling, we show that for the metabolically stable patient (in whom the solute generated during the dialysis cycle, typically, 1 week, is equal to the solute removed from the body), DAIs estimated for the dialysis cycle are in general independent of the average solute generation rate (although they may depend on the pattern of oscillations in the generation rate). However, the alternative adequacy parameters (such as EKR, stdKT/V, and SRI) may depend on solute generation rate for metabolically unstable patients.

Nocturnal hemodialysis

Patients receiving conventional hemodialysis have high hospitalisation rates, poor quality of life and survival compared to the general population. Many centres around the world are providing longer hours of hemodialysis - short daily hemodialysis and nocturnal hemodialysis - with a view to improving patient survival and quality of life. Studies have shown that nocturnal haemodiaysis is more effective than conventional hemodialysis in clearing most small, middle and larger molecule toxins and suggest nocturnal dialysis enhances patient survival and quality of life. Concerns include patient acceptance, vascular access related complications and increased cost. The purpose of this review is to examine the advantages and drawbacks of nocturnal dialysis, with a focus on applicability to India where the renal physician has to face cultural and economic barriers, erratic power supply and poor water quality.

Nocturnal hemodialysis: effects on solute clearance, quality of life, and patient survival

PURPOSE OF REVIEW

Conventional hemodialysis is often an incomplete treatment for uremia. People receiving hemodialysis often report a poor quality of life and suffer from an accelerated mortality rate. Nocturnal hemodialysis provides long treatments at night in the home or dialysis center. This review will examine how long nocturnal treatments have impact on the clearance of small and larger retention products, and how these treatments influence quality of life and survival.

RECENT FINDINGS

Nocturnal hemodialysis is more effective at clearing most small and middle molecule retention products, and has been associated with improvements in quality of life, especially in those domains related to the effects of kidney disease. Survival on nocturnal hemodialysis is higher than expected, and studies suggest that patients receiving nocturnal hemodialysis have a mortality rate that is about one third of what is seen in similar patients receiving conventional hemodialysis.

SUMMARY

Although impressive, it is difficult to be sure how much of the results of these studies is due to the duration and timing of dialysis and how much relates to patient level factors and residual confounding, and further research in this area is required.