Miniaturized Artificial Kidney Based on Hemoperfusion Ultrafiltration

A third approach is to construct a truly miniaturized artificial kidney based on hemoperfusion in series with small ultrafiltrator (Chang etal., 1975, 1979a, 1977b, Chang, 1976c) (Fig. 10.9). In clinical studies, a small Amicon ultratiltrator was used (Fig. 10.11). Hydrostatic pressure from the blood pump alone gave effective ultrafiltration. Dialysis fluid is not required, the ultrafiltrate flowing directly into a measuring cylinder.

This ultrafiltrator in series with ACAC hemoperfusion was studied in two patients, one for three and the other for six months. The patient, treated for 6 months, had a creatinine clearance of 0.2 mL/min

Fig. 10.11. ACAC hemoperfusion in series with a small ultrafiltrator.

and a urine volume of 50 ml/day. He was followed for a 6-month control period of thrice weekly hemodialysis treatments. This was followed by a 6-month test period when a 2.5 h hemoperfusion-ultrafiltration replaced one of the 6h three weekly hemodialysis treatments (Fig. 10.12).

The patient felt well throughout. Hematocrit increased slightly from 25.15% ± 3.61 to 26.6% ± 1.73. Fluid retentions diminished as body weight fell from 82.6 ±1.2 to the optimal dry weight of 78.0 ± 0.8 kg and hypertension improved. More fluid could be removed without side effects in 2.5 h of hemoperfusion-ultrafiltration compared to 6 h of hemodialysis. "Middle" molecule clearance in this patient was 113 mL/min at a blood flow rate (QB) of 200 ml/min and 160 mL/min at

Control

Test

Post-test

6 months

6 months

6 months

30%

____

, 0 Hematocrit

o--- "

0

100

--o bun

0

20

____

O Creatinine

(j----

o

_•-

- 0 Uric acid

0

180

O'--

^ Body weight

- - - - ■ (dry weight)

120

10

--

-•-

-o Ca mg/dl

o

-m

0 P mg/dl

0--

O K meq/L

0

Fig. 10.12. Laboratory data of patient. 6-month control period followed by 6-month test period. During the 6-month test period, one of the weekly 6h hemodialysis treatment was replaced by 2.5 h of treatment using the miniaturized hemoperfusion-ultrafiltration device.

Fig. 10.12. Laboratory data of patient. 6-month control period followed by 6-month test period. During the 6-month test period, one of the weekly 6h hemodialysis treatment was replaced by 2.5 h of treatment using the miniaturized hemoperfusion-ultrafiltration device.

Table 10. Patient on Hemoperfusion-Ultrafiltraion

Clearance (ml/min) (Blood Flow: 300 ml/min)

Hemoperfusion

Hemoperufsion-Ultrafiltration

Creatinine

230

235

Uric acid

235

235

300-1500 MW

120

134

PTH free

73

81

Fluid removal/2 h

0

2500-2700 ml

NaCl removal/2 h

0

17.0-18.4 g

creatinine clearance: 0.2ml/min;urine output: 50 ml/24 h creatinine clearance: 0.2ml/min;urine output: 50 ml/24 h a QB of 300. This was significantly higher than for hemodialysis. Nerve conduction velocity did not change. Hemoperfusion-ultrafiltration was more effective than hemodialysis in removing "middle" molecules, creatinine, uric acid, sodium chloride and water (Table 10). On the other hand, it did not remove sufficient potassium and urea since after 6 months on this regime, there was an increase in mean blood urea nitrogen from 86 ± 14mg/dl to 105 ± 18mg/dl and potassium from 5.2 ± 0.57mEq/l to 5.8 ± 0.08mEq/l. Oral adsorbents can remove potassium and phosphate. An urea removal system is being developed to complete this miniaturized artificial kidney system. For this, artificial cells containing multi-enzyme systems and artificial cells containing urea removing microorganisms are being investigated.

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