1. Volume 65, Issue 4, Pages 1499-1510 (April 2004)
Model-based study of the effects of the hemodialysis technique on the compensatory response to hypovolemia 
Silvio Cavalcanti, Andrea Ciandrini, Stefano Severi, Fabio Badiali, Stefano Bini, Andrea Gattiani, Leonardo Cagnoli, Antonio Santoro 
Kidney International 
Volume 65, Issue 4, Pages (April 2004)
DOI: /j x
Copyright © 2004 International Society of Nephrology Terms and Conditions

2. Figure 1
Block diagram illustrating the model used to simulate the short-term compensatory mechanisms to hypovolemia. Variations of arterial (Pa) and right atrial (Pra) pressures compared with the values at the beginning of treatment (Pae and Prae, respectively) excite the efferent adrenergic tone (T), which actuates vasoconstriction of both venous (Vvu) and microcirculatory (Rm) vessels, as well as improving cardiac function through inotropic regulation of stroke volume (SV) and chronotropic regulation of heart rate (HR). Adrenergic stimulation modifies the conditions of effectors relative to initial values (Vvue, Rme, SVe, and HRe). The effectiveness of each of these regulatory pathways was characterized by a parameter (Kv, Kr, Ksv, and Khr) that can range from 0 to 1 (0 = total inhibition and 1 = maximal efficiency).
Kidney International  , DOI: ( /j x)
Copyright © 2004 International Society of Nephrology Terms and Conditions

3. Figure 2
Comparison of hypotensive episodes and collapse. (A) Frequency of dialyses complicated by hypotensive episodes [hypotension 51%± 30% for bicarbonate dialysis (BD) vs. 27%± 30% for acetate-free biofiltration (AFB)] and by at least one symptom (symptoms 18%± 19% for BD vs. 7%± 15% for AFB). Frequencies were calculated for each patient as the incidence of sessions with complications over the six BD and six AFB sessions, respectively; mean ± standard deviation of these frequencies for the 11 patients are shown. (B) Percentage reduction in blood volume before the hypotension episode [collapse percentage reduction of blood volume (%R-BV) 7.9%± 2.0%, N = 34 for BD vs. 10.9%± 2.6%, N = 18 for AFB) and time of hypotension (collapse time 123 ± 41 minutes for BD vs. 183 ± 25 minutes for AFB).
Kidney International  , DOI: ( /j x)
Copyright © 2004 International Society of Nephrology Terms and Conditions

4. Figure 3
Bland-Altman scatter plot of differences between simulated and measured heart rate (A), systolic pressure (B), and diastolic pressure (C) for bicarbonate dialysis (BD) (○) and acetate-free biofiltration (AFB) (+). Mean values ± standard deviations of the differences were: 0.01 ± 4.59bpm for heart rate, 0.74 ± 6.46mm Hg for systolic pressure, and ± 6.38mm Hg for diastolic pressure.
Kidney International  , DOI: ( /j x)
Copyright © 2004 International Society of Nephrology Terms and Conditions

5. Figure 4
Percentage reduction in blood volume in 12 bicarbonate dialysis (BD) (•) and in 12 acetate-free biofiltration (AFB) (▪) sessions without hypotension. No significant difference was found between the two treatments (see Table 3).
Kidney International  , DOI: ( /j x)
Copyright © 2004 International Society of Nephrology Terms and Conditions

6. Figure 5
Comparison of simulated and measured arterial pressure and heart rate (mean±SD) in bicarbonate dialysis (BD) (A) and acetate-free biofiltration (AFB) (B) sessions without hypotension. Model simulated pressure and heart rate (continuous lines) used the percentage reduction of blood volume (%R-BV) curves shown in Figure 4. as input. For the simulation, the mean values of parameters identified in the hypotension-free sessions (see Table 4) were assigned (BD Kv= 0.35, Kr= 0.24, and Ksv= 0.21; AFB Kv= 0.60, Kr= 0.90, Ksv= 0.73).
Kidney International  , DOI: ( /j x)
Copyright © 2004 International Society of Nephrology Terms and Conditions

7. Figure 6
Percentage changes in total peripheral resistance (TPR) (A), cardiac output (CO) (B), venous pressure (Pv) (C), and stroke volume (SV) (D) simulated by the model during bicarbonate dialysis (BD) and acetate-free biofiltration (AFB) without hypotension. The percentage reduction of blood volume (%R-BV) curves used as model inputs are shown in Figure 4. Parameters are those reported in Figure 5. Peripheral resistance and stroke volume exhibited notable differences.
Kidney International  , DOI: ( /j x)
Copyright © 2004 International Society of Nephrology Terms and Conditions

8. Figure 7
Percentage change of systolic pressure simulated by the model during a treatment that produces a percentage blood volume reduction of 15% after 4hours. The parameter values used for the simulations are the mean values identified in hypotensive sessions [bicarbonate dialysis (BD) Kv= 0.02, Kr= 0.05, Ksv= 0.05; acetate-free biofiltration (AFB) Kv= 0.01, Kr= 0.49, Ksv= 0.50]. The critical percentage reduction of blood volume (%R-BV) for the occurrence of hypotensive episodes in BD and AFB treatments are also shown (mean ± SD).
Kidney International  , DOI: ( /j x)
Copyright © 2004 International Society of Nephrology Terms and Conditions