**5.3.5 Improvement of dialysis delivery**

Hemodialysis and UF may cause vasoconstriction of peripheral vascular beds, thus reducing peripheral tissue perfusion. This phenomenon may cause sequestration of urea, as only a central vascular loop of blood remains to be dialyzed. When hypotension occurs, this phenomenon may be aggravated leading to enhanced urea compartmentalization and reduced HD efficiency. Hence, it was proposed that improved hemodynamic stability during dialysis may improve urea removal and increase Kt/V.

Ronco et al. (2000) conducted a multi-center, cross-over randomized trial of 12 IDH-prone patients treated for two weeks with acetate-free biofiltration (AFB, schedule A) and for two weeks with AFB plus Hemocontrol® (schedule B). Parameters of urea kinetics were significantly improved when patients were on schedule B, with higher equilibrated Kt/V (1,12 vs. 1,03, p<0,001), and lower urea rebound at 30 minutes post-HD (6,4 vs. 14,2 g, p<0,001), despite similar predialysis urea concentration, HD prescriptions and treatment time.

However, a larger randomized trial of 26 patients followed for 12 weeks and treated with standard HD or BVM-controlled HD in a cross-over fashion did not find any significant improvement of equilibrated Kt/V in the treatment group (1,17 vs. 1,12, p=0,156) in spite of a slightly but significant higher treatment time and a 20% reduction of intradialytic morbid events (Gabrielli et al., 2009).

### **5.3.6 Morbidity and mortality**

With improved hemodynamic tolerance, reduction of left ventricular wall dysfunction, and superior dialysis delivery, it would be reasonable to assume that the use of biofeedback systems would improve morbidity and mortality in chronic dialysis patients. Unfortunately, no trial to date has examined this issue and the question remains open.

Nevertheless, one large trial published in 2005 assessed the effect on morbidity of a BVmonitor based algorithm of UF control versus conventional management of volemia. The CLIMB (Crit-Line® Intradialytic Monitoring Benefit) study (Reddan et al., 2005) was a

the standard group was as effective, and the overall difference between the groups was not

In summary, no randomized trial has clearly demonstrated that the use of biofeedback devices is superior to standard HD and clinical judgement in reducing dry weight in volume expanded patients. Biofeedback devices may be of value in reducing blood pressure in hypertensive patients, although a systematic and clinical treatment algorithm may be as

Cardiovascular morbidity and mortality are extremely high among chronic HD patients. Aside from the conventional risk factors for atherosclerosis, it was proposed that recurrent subclinical myocardial ischemia occurring during HD, as a result of silent decrease in myocardial perfusion, may contribute to the excessive cardio-vascular burden. In support of this hypothesis, Selby et al. (2006) demonstrated that reversible regional wall motion abnormalities which develop in a majority of hypotension-prone patients during HD, were substantially reduced with biofeedback dialysis. However, the observation period in this study was only 4 weeks, and it is unknown at the present time whether biofeedback HD

Hemodialysis and UF may cause vasoconstriction of peripheral vascular beds, thus reducing peripheral tissue perfusion. This phenomenon may cause sequestration of urea, as only a central vascular loop of blood remains to be dialyzed. When hypotension occurs, this phenomenon may be aggravated leading to enhanced urea compartmentalization and reduced HD efficiency. Hence, it was proposed that improved hemodynamic stability

Ronco et al. (2000) conducted a multi-center, cross-over randomized trial of 12 IDH-prone patients treated for two weeks with acetate-free biofiltration (AFB, schedule A) and for two weeks with AFB plus Hemocontrol® (schedule B). Parameters of urea kinetics were significantly improved when patients were on schedule B, with higher equilibrated Kt/V (1,12 vs. 1,03, p<0,001), and lower urea rebound at 30 minutes post-HD (6,4 vs. 14,2 g, p<0,001),

However, a larger randomized trial of 26 patients followed for 12 weeks and treated with standard HD or BVM-controlled HD in a cross-over fashion did not find any significant improvement of equilibrated Kt/V in the treatment group (1,17 vs. 1,12, p=0,156) in spite of a slightly but significant higher treatment time and a 20% reduction of intradialytic morbid

With improved hemodynamic tolerance, reduction of left ventricular wall dysfunction, and superior dialysis delivery, it would be reasonable to assume that the use of biofeedback systems would improve morbidity and mortality in chronic dialysis patients. Unfortunately,

Nevertheless, one large trial published in 2005 assessed the effect on morbidity of a BVmonitor based algorithm of UF control versus conventional management of volemia. The CLIMB (Crit-Line® Intradialytic Monitoring Benefit) study (Reddan et al., 2005) was a

despite similar predialysis urea concentration, HD prescriptions and treatment time.

no trial to date has examined this issue and the question remains open.

significant.

useful.

**5.3.4 Reduction of left ventricular dysfunction**

provides any benefit on long-term cardiac dysfunction.

during dialysis may improve urea removal and increase Kt/V.

**5.3.5 Improvement of dialysis delivery**

events (Gabrielli et al., 2009).

**5.3.6 Morbidity and mortality**

multi-centered, randomized, controlled trial of 443 chronic HD patients followed for 6 months during which ultrafiltration was either managed according to Crit-Line® values of RBV reduction, or by usual clinical strategies. Patients were not selected on a basis of prior IDH history, and the algorithm of the treatment group was only proposed and not mandatory. During the follow-up period, there were no statistically significant differences between the two groups regarding the number of IDH, the occurrence of intradialytic symptoms and the control of BP. Surprisingly, the risk ratios for both non-access and accessrelated hospitalizations were higher in the Crit-Line® group (adjusted RR 1,61 and 1,52; pvalue 0,01 and 0.04, respectively). Mortality was 8.7% in the treatment group and 3.3% in the control group (p=0.021). The authors concluded that the availability of Crit-Line® may alter clinicians' behaviour and may cause a risk for patients, although these results have to be interpreted cautiously since the control group had an atypically low hospitalization and mortality rate.
