**8. References**


IDH is the most frequent complication of dialysis, and is associated with significant patient morbidity. Although pathogenesis is multifactorial, blood volume reduction appears to be central in the development of such events, especially when cardio-vascular compensatory mechanisms are impaired. In an attempt to reduce hypotensive episodes, blood volume biofeedback devices have been developed. The underlying premise of such devices is to automatically adjust dialysis parameters such as UF rate and dialysate conductivity, in response to variations of monitored patient's characteristics, in order to make dialysis sessions more physiological and to prevent IDH by acting on subclinical signs of hemodynamic instability. Evidence supports BV biofeedback in hypotensive prone patients to reduce occurrence of IDH, nursing interventions, and probably intra- and inter- dialytic symptoms, although no large scale randomized trial has been published to date. BV biofeedback may also be helpful to enhance vascular tolerance in stable patients, but literature is limited. Data concerning improvement of hypertension and volume overload, as well as improvement of dialysis delivery, is conflicting. Finally, there is no large randomized trial that assessed the impact of automatic BV control on morbidity and mortality. Data suggesting that Crit-line® based algorithm of hypertension management is associated with higher hospitalisation and mortality rates are of concern. Larger and longterm randomized trials comparing BV biofeedback devices to standard HD are needed to

better define the impact of these novel technologies on patient outcomes.

Andrulli, S., Colzani, S., Mascia, F., Lucchi, L., Stipo, L., Bigi, MC., Crepaldi, M., Redaelli, B.,

Bégin, V., Déziel, C. & Madore, F. (2002). Biofeedback regulation of ultrafiltration and

Burton, JO., Jefferies, HJ., Selby, NM. & McIntyre CW. (2009). Hemodialysis-induced cardiac

Dasselaar, JJ., Huisman, RM., De Jong, PE. & Franssen, CFM. (2007a). Relative blood volume

Dasselaar, JJ., Huisman, RM., De Jong, PE., Burgerhof, JGM. & Franssen, CFM. (2007b).

volume status in hypertensive patients. *ASAIO J.* Vol.53, No.3, pp. 357-364 Daugirdas, JT. (2001). Pathophysiology of dialysis hypotension: an update. (2001). *Am J* 

devices. *Hemodialysis International*. Vol.11, No.4, pp. 448-455

*Kidney Dis*. Vol.38, No.4, suppl 4, pp. S11-S17

Albertazzi, A. & Locatelli, F. (2002). The role of blood volume reduction in the genesis of intradialytic hypotension. *Am J Kidney Dis.* Vol.40, No.6, pp. 1244-54 Basile, C., Giordano, R., Vernaglione, L., Montanaro, A., De Maio, P., De Padova, F.,

Marangi, AL., Di Marco, L., Santese, D., Semeraro, A. & Liogorio, VA. (2001). Efficacy and safety of haemodialysis treatment with the Hemocontrol biofeedback system: a prospective medium-term study. *Nephrol Dial Transplant.* Vol.16, No.2,

dialysate conductivity for the prevention of hypotension during hemodialysis.

injury: determinants and associated outcomes. *Clin J Am Soc Nephrol.* Vol.4, No.5,

measurements during hemodialysis: Comparisons between three noninvasive

Effects of relative blood volume-controlled hemodialysis on blood pressure and

**7. Conclusions**

**8. References**

pp. 328-334

pp. 914-20

*ASAIO J.* Vol.48, No.3, pp. 312-315


**3** 

*USA* 

**Sodium and Hemodialysis** 

The original dialysate sodium prescription was 126.5 mEq/L (Kolff, 1947). Before volumetric controlled ultrafiltration, sodium was removed primarily, slowly and most predictably by diffusion. With the development of high flux dialysis membranes, dialysate osmolality asserted a faster and more dramatic effect on serum osmolality. Hypotonic dialysate rapidly drops serum osmolality that leads to net fluid shift out of the vascular space, causing significant intradialytic symptoms (Stewart et al., 1972). Further, the duration of dialysis sessions was shortened as clearance of urea was improved, requiring an accelerated rate of

To counter symptoms of hypo-osmolarity and rapid ultrafiltration, dialysate sodium concentration was increased. In the early 1970s, Stewart demonstrated less cramping with sodium of 145 mEq/L than with 132 mEq/L (Stewart et al., 1972). In the early 1980s, Locatelli showed improved cardiovascular stability when sodium concentration was raised to 148 mEq/L from 142 mEq/L (Locatelli et al., 1982). As the sodium prescription increased, concerns about sodium overloading arose. In 1985, Cybulsky demonstrated worsening of hypertension in already hypertensive patients (Cybulsky et al., 1985); and Daugirdas showed increasing thirst and interdialytic weight gain (IDWG), in both level and modelled high sodium techniques (Daugirdas et al., 1985). Nevertheless, intradialytic hemodynamic stability remained a valid concern and the data were not always clear. For example, Barré showed no worsening of hypertension and pulmonary edema at [Na+] 145, 150 and 155 mEq/L (Barré, 1988). The technique of sodium modelling offered a theoretical means to attenuate the risk of sodium loading. By the early 1990s, Acchiardo advocated, "[s]odium modelling [149mEq/L dropping to 140 mEq/L] should always be used in patients being maintained on high flux dialysis" (Acchiardo & Hayden, 1991). This approach was widely practiced throughout the 1990s. After more than a decade of high sodium and sodium profiling dialysis, trends toward exacerbation of hypertension and interdialytic weight gain

Despite a growing body of literature on the effects of dialysis sodium, the sodium prescription is frequently overlooked or ineffectually utilized. Further, despite the increasing sophistication of dialysis delivery systems, the sodium prescription is often not adjusted to suit individual patient needs. First, we will erect a conceptual framework for understanding the dialysate sodium prescription. Second, we will review the primary literature regarding dialysate sodium and outcomes. Third, we will formulate recommendations on prescribing dialysate sodium. Finally, we will explore the technical and systems challenges to adjusting the actual sodium delivered to an individual patient.

**1. Introduction** 

ultrafiltration.

were becoming evident (Song, 2002).

Matthew Gembala and Satish Kumar

*University of Oklahoma* 

