Customized bicarbonate buffered dialysate and replacement solutions for continuous renal replacement therapies: effect of crystallization on the measured levels of electrolytes and buffer

A comparison of the potential for acute cardiopulmonary adverse effects in dogs during continuous veno-venous hemofiltration with accusol 35 solution with and without induced calcium carbonate particles

BACKGROUND

Baxter received reports of visible precipitate, identified as calcium carbonate, forming during hemofiltration with Accusol 35 solution.

AIM

To evaluate the potential for acute cardiopulmonary adverse effects of Accusol 35 containing exaggerated calcium carbonate particles.

METHODS

Anesthetized dogs underwent continuous veno-venous hemofiltration (CVVH) with Accusol 35 containing visible and subvisible particles (≥10 µm) 36 times higher than the maximum concentration specified in the European Pharmacopoeia (P-Accusol), or Accusol 35 conforming to specification (Accusol). Select cardiovascular and blood gas parameters were evaluated during CVVH. Lung tissue samples were collected following CVVH.

RESULTS

No differences were observed in cardiovascular and blood gas parameters or lung histology between P-Accusol and Accusol.

CONCLUSION

Accusol 35 containing visible and subvisible particles (≥10 µm) 36 times higher than the maximum concentration specified in the European Pharmacopoeia resulted in no acute cardiopulmonary adverse effects compared with Accusol 35 containing no visible particles and subvisible particles within European Pharmacopoeia specification.

Purity and stability of online-prepared hemodiafiltration fluid after storage

BACKGROUND/AIMS

Previous studies have suggested that online hemodiafiltration (OL-HDF) fluid can be used as dialysate for continuous renal replacement therapies, and thus HDF costs can be reduced. The aims of this study were to determine the purity of OL-HDF fluid and to verify the stability of the electrolyte composition and acid-base balance during its storage.

METHODS

OL-HDF fluid was collected in 70 individual bags and stored for up to 7 days. The following tests were performed daily in 10 bags: natural visible precipitation (macrocrystallization), sample collection for chemical analysis and fluid culture, limulus amebocyte lysate endotoxin test, standard culture of NALGENE® filters after passing of the fluid, and molecular analysis of bacterial DNA.

RESULTS

The values of pH and pCO(2) showed a significant change starting at 24 h (p < 0.001); after 72 h, their values were beyond the measurable range. Coefficient of variation for pCO(2) was as high as 25.7%. Electrolyte composition (Na(+), K(+), Cl(-), Ca(2+) and glucose) showed a statistically significant difference over time (p < 0.05); however, their coefficients of variation were low (1.7, 1.4, 0.6, 2.3 and 0.9%, respectively), which might not be considered clinically significant. Negative results were obtained at all points by fluid and filter cultures, endotoxin test and molecular analysis. No macrocrystallization was observed at any time point.

CONCLUSIONS

We demonstrate the microbiological purity of OL-HDF fluid stored for up to 7 days. The electrolyte composition was stable, except for a relevant change in pCO(2) and consequently in pH (first noted at 24 h), emphasizing the need to reassess the acid-base balance in multilayer plastic bags in future studies.

Development of a clipped single-bag with bicarbonate replacement fluid to ensure proper mixing

A clipped single-bag for bicarbonate replacement fluid was developed to ensure proper mixing before administering to the patient. Nonmixture can cause imbalances of electrolytes and pH, which is a key problem for the current double-bag type bicarbonate replacement fluid sets. To resolve this problem, this single bag properly mixes the solutions before use. The new bag consists of a clip that is placed in the middle to keep the two solutions separated and sealed. When the caregiver is ready to administer treatment, the bag is simply unfolded and the clip automatically detaches, releasing the fluids. Thereby, the bicarbonate fluids are effectively mixed. An optimal clip size with an outer diameter of 16 mm and thickness of 2 mm was determined using compression tests and drop tests. This bag may be a safer and more effective way to provide proper replacement fluid supply for both hemofiltration and hemodiafiltration.

Effects of customized bicarbonate buffered solutions for continuous renal replacement therapies on polymorphonuclear leukocytes function and viability

It has previously been shown that the mixture of bicarbonate and calcium in the solutions used for continuous renal replacement therapy led to crystallization and significant changes in calcium concentration and pH. The aim of this study was to investigate the impact of bicarbonate/calcium and lactate/calcium solutions for Continuous Renal Replacement Therapies (CRRT) on the viability and function of polymorphonuclear cells (PMN). We tested four customized bicarbonate buffered solutions: single bag (bicarbonate and calcium mixed 24 h before testing), double bag (mixed immediately before testing), filtered single bag and double bag solutions, and a commercial lactate buffered solution. Blood from 6 volunteers was incubated with the solutions for 30 min followed by PMN isolation. After overnight incubation, viability, phagocytosis, and peroxide production by PMN were determined by flow cytometry. There was no difference between the test solutions with respect to PMN viability and function. Therefore, the presence of microcrystals and the consequent changes in electrolyte concentrations do not seem to impair PMN function.

Rationale and experience with short daily hemofiltration

Patients with end-stage renal disease (ESRD) have morbidity and mortality rates that are much higher than those found in the general population. The nonphysiologic nature of thrice-weekly hemodialysis may be partially responsible for the poor outcomes in this patient population. In response to the problems encountered with conventional hemodialysis schedules, a number of investigators have explored potential solutions to the problem. One such solution is to increase the time and/or frequency of hemodialysis. With this approach, ESRD patients have been observed to have better anemia management and blood pressure control, as well as improvements in quality of life. Hemodialysis is based on diffusion of solutes across a semipermeable membrane such that only small molecules are readily removed. Therefore a second solution has been to utilize hemofiltration instead of hemodialysis. Hemofiltration utilizes convective clearance of molecules, resulting in an improvement in the removal of larger solutes, much like the glomerular basement membrane of the kidney. Despite the accumulated evidence that thrice-weekly hemofiltration adds to the benefits seen with increasing hemodialysis time and/or frequency, the use of hemofiltration has been limited by the available technology, cost, and low access blood flows. However, current technological advances in equipment and access creation are addressing these problems. With these advances, a number of investigators have also explored the potential benefits of daily hemofiltration as a treatment option for ESRD. The preliminary results suggest that improvements in blood pressure, beta2-microglobulin (beta2M) levels, and quality of life are possible.