Page 704 - Fluid, Electrolyte, and Acid-Base Disorders in Small Animal Practice

Hemodialysis and Extracorporeal Blood Purification 691

TABLE 29-1 Recommended Extracorporeal Volumes and Characteristics of
Hemodialyzers Used for Hemodialysis in Dogs and Cats
Total
Body Dialyzer Extracorporeal
Weight Volume Volume % BV

Cats, dogs <6kg <20 mL <60 mL 13-40
Cats >6kg <30 mL <70 mL <23
Dogs 6-12 kg <45 mL <90 mL 9-19
Dogs 12-20 kg <80 mL 100-160 mL 6-17
Dogs 20-30 kg <120 mL 150-200 mL 6-13
Dogs >30 kg >80 mL 150-250 mL 6-10
Kuf Area Volume
Kd urea Kd creat Kd phos Kd B12
2
Dialyzer (mL/min) (mL/min) (mL/min) (mL/min) (mL/hr/mm Hg) (m ) (mL)
Low Volume/Flux Dialyzer
F3* 125 95 47 20 1.7 0.4 28
F4* 155 128 78 32 2.8 0.7 42
F5* 170 149 103 45 4.0 1.0 63
F6* 180 164 123 60 5.5 1.3 82
F7* 184 169 132 68 6.4 1.6 98
F8* 186 172 138 76 7.5 1.8 110
High-Flux Dialyzer
Polyflux 6H { 167 146 137 90 33 0.6 52
F40* 165 140 138 75 20 0.7 42
F80 A* 190 180 177 135 55 1.8 110
Polyflux Revaclear { 196 189 185 144 50 1.4 84
Polyflux Revaclear Max { 198 195 191 158 60 1.8 100
Polyflux F140 H { 193 181 174 128 60 1.4 94
Polyflux170 H { 196 186 180 137 70 1.7 115
Optiflux F160 NR* 194 181 178 128 45 1.5 84
Optiflux F180 NR* 196 187 180 141 55 1.8 105
Optiflux F200 NR* 197 191 183 148 56 2 112
In vitro clearances @ Q b , 200 mL/min; Qd, 500 mL/min; UF, 0 mL/hr.
All conventions as defined in the text.
*Fresenius Medical Care, North America.
{ Gambro Renal Products, CO.

inadequate URR outcomes that delay resolution of the rate of urea reduction is more likely to cause intradialytic
azotemia. A patient with an initial BUN concentration complications than the absolute decrease in BUN over
of 250 mg/dL treated for 120 minutes to yield a URR the dialysis session. 96 The risk of dialysis disequilibrium
of 0.2 (0.1 URR/hr, postdialysis BUN, 200 mg/dL) syndrome can be minimized by adherence to the hourly
may rebound to a BUN approaching 250 mg/dL by URR recommendations as indexed to the degree of azo-
the next treatment. The subsequent treatment will be temia in Table 29-2. With these guidelines, an appropri-
constrained by the same concerns for rapid urea reduction ate treatment time can be determined readily by dividing
and dialysis disequilibrium at issue for the initial treat- the URR goal for the treatment by the designated hourly
ment because no progress was made to resolve the azote- URR. Animals become more tolerant to rapid urea shifts
mia. A safe and more effective approach for initial as their azotemia is reduced and as the number of dialysis
treatments is to prescribe extended-slow dialysis to target treatments is increased. More aggressive hourly URR
a URR between 0.4 and 0.5 (or more) over 4 to 8 (or goals can be prescribed beyond the initial two to three
more) hours. Once the predialysis BUN is less than treatments at a later stage of management. It should be
150 mg/dL, dialysis time can be maintained or increased emphasized that URR is determined cumulatively over
in both dogs and cats concurrent with faster blood flow the entire dialysis treatment, but the rate and absolute
rates to achieve higher URRs. change in serum urea and osmolality will be highest at
The hourly URR can be used as an additional guide to the beginning of the treatment. Despite appropriate
determine the appropriate treatment time. An excessive URR prescription for the treatment, hourly URR