A resource of Calculate by QxMD at https://www.qxmd.com/calculate
Over 400 decision support tools available • get the app for iOS or Android at qx.md/calculate
Options for correction of metabolic acidosis in patients with AKI include acetate, lactate, bicarbonate, and citrate. The use of acetate has been largely abandoned in view of the associated hemodynamic instability and weight loss, probably related to excessive nitric oxide production and cytokine synthesis.748 Citrate, used for regional anticoagulation of the extracorporeal circuit, is alkalinizing, and most patients receiving citrate anticoagulation do not need an additional buffer in the dialysate or replacement fluid.
Original HF solutions contained lactate as a buffer. Under normal circumstances, this lactate is metabolized, resulting in adequate correction of acidosis in most patients. A survey in 34 Australian ICUs concluded that 55% of the ICU patients with AKI were treated with lactate-based solutions710 that, in most countries, are less expensive than bicarbonate solutions. In addition, bicarbonate solutions have a higher risk of bacterial contamination and the solution is unstable in the presence of calcium and magnesium. However, in recent years, bicarbonate has gained popularity because of concerns that lactate may not be rapidly metabolized in the setting of multiple-organ failure.749 Since lactate is a strong anion, insufficient lactate conversion will result in worsening acidosis, especially since bicarbonate losses are ongoing in the extracorporeal circuit. Hyperlactatemia has also been linked to impaired cellular function and catabolism due to lowering of the cellular redox state and phosphorylation potential.750 In addition, iatrogenic increases in lactate levels may lead to misinterpretation of the clinical situation. The risk of ‘‘lactate intolerance’’ is highest in patients with liver failure (impaired lactate clearance) or circulatory shock (increased endogenous lactate production).
Few adequately designed trials have compared different buffers during RRT in AKI patients, and most of them have been performed during CRRT. Barenbrock et al.751 randomized 117 AKI patients to CVVH with lactate or bicarbonate replacement fluid. The use of bicarbonate resulted in better correction of acidosis and lower lactate levels. Also, the incidence of hypotension and other cardiovascular events was lower with bicarbonate. In the subgroup of patients with cardiac failure, mortality tended to be lower with bicarbonate, whereas in the subgroup of septic patents no difference in outcome was found (Suppl Table 36). A nonrandomized crossover study in 54 patients with multiple-organ dysfunction undergoing CVVHDF confirmed the superior control of acidosis and better hemodynamic tolerance with bicarbonate.752 However, another RCT in 40 patients treated with CVVH could not find a difference in hemodynamic tolerance, despite the higher lactate levels in the lactatebuffered group.753 Differences in the case-mix may explain these different results.
Two small prospective randomized crossover comparisons of bicarbonate- and lactate-buffered solutions in AKI patients treated with CVVH or CVVHDF found elevated serum lactate levels with lactate, an effect that was more pronounced in patients with hepatic insufficiency.754,755 An observational trial in 27 patients found a compromised lactate tolerance in patients with coincidental liver disease, those on inotropic support, and in patients with initial blood lactate measurements of > 90.1 mg/dl ( > 10 mmol/l) and large base deficits.756
In conclusion, the use of bicarbonate as a buffer in the dialysate or replacement fluid of AKI patients results in better correction of acidosis, lower lactate levels, and improved hemodynamic tolerance. This effect is most pronounced in patients with circulatory problems and in those with liver dysfunction.
| ANSI/AAMI/ISO763–765 | ERA-EDTA guidelines765a | |
|---|---|---|
| Water for dialysis | ||
| Bacteria (CFU/ml) | < 100 (action level at 50) | < 100 |
| Endotoxin (EU/ml) | < 0.5 | < 0.25 |
| Dialysate | ||
| Bacteria (CFU/ml) | < 100 (action level at 50) | < 100 |
| Endotoxin (EU/ml) | < 0.5 | < 0.25 |
| Ultrapure dialysate | ||
| Bacteria (CFU/ml) | < 0.1 | < 0.1 |
| Endotoxin (EU/ml) | < 0.03 | < 0.03 |
| Substitution fluid for infusion | ||
| Bacteria (CFU/ml) | Sterile | < 10-6 |
| Endotoxin (EU/ml) | Undetectable | < 0.03 |
AAMI, Association for the Advancement of Medical Instrumentation; ANSI, American National Standards Institute; CFU, colony-forming units; ERA-EDTA, European Renal Association—European Dialysis and Transplant Asssociation; EU, endotoxin units; ISO, International Organization for Standardization.
Do you have an enquiry or suggestion? Get in touch with us through Twitter @QxMD, Facebook QxMD, or email contact@qxmd.com