Quantification of Systemic Delivery of Substrates for Intermediate Metabolism during Citrate Anticoagulation of Continuous Renal Replacement Therapy

Abstract

Background: There are limited data on systemic delivery of metabolic substrates during citrate anticoagulation. The direct citrate measurements are usually not available. Methods: Patients on 2.2% acid-citrate-dextrose (ACD, n = 41) were compared to a control group on unfractionated heparin (n = 17). All were treated on 1.9-m² polysulfone filters. Samples were taken from the central venous catheter, ports pre- and post-filter and from effluent. Results: The gain of citrate in CVVH (n = 18) was not different from CVVHDF (n = 23, p = 0.8). Mean gain of citrate was 25.4 ± 6.4 mmol/h. The systemic loads of lactate (p = 0.12) and glucose (p = 0.23) in CVVH were similar to CVVHDF. Mean inputs of lactate and glucose were 62.9 ± 21.1 and 26.6 ± 10.4 mmol/h, respectively. The mean difference between post- and prefilter unmeasured anions (d-UA) correlated with mean difference of citrate concentrations (p < 0.0001, r² = 0.66). The estimated caloric load of the citrate modalities was 5,536 ± 1,385 kJ/ 24 h. Conclusions: ACD might represent a significant load of metabolic substrates, particularly if used with lactate buffer. Systemic delivery of citrate can be predicted using d-UA in the extracorporeal circuit.

Continuous renal replacement therapy: a potential source of calories in the critically ill,

“…In the absence of high lactate delivery, a substantial gain or loss of energy would not be expected from the replacement fluids because of the small difference in glucose concentrations between these fluids and blood. The only previous demonstration of energy gain with the use of citrate for anticoagulation to our knowledge is that from Balik et al (10,11), who reported that when an acid-citrate-dextrose solution is used with high lactate replacement fluids, CRRT can provide #1300 kcal/d. Our results are more relevant to the most recently published Improving Global Outcomes Acute Kidney Injury Work Group acute kidney injury guidelines (14), which recommend lactate-free replacement fluids.…”

“…In patients who require nutritional support, there is a strong relation between the amount of feeding administered and both hyperglycemia and insulin requirements (8). Continuous renal replacement therapy (CRRT) is now used universally in hemodynamically unstable individuals with acute and chronic kidney impairment, and it has been recognized as a potential source for macronutrient losses as well as macronutrient uptake, depending on the composition of the fluids used (9)(10)(11)(12). However, to our knowledge, the possibility for net macronutrient uptake has not been mentioned in published guidelines from nephrology and nutrition societies (13)(14)(15).…”

The Effects of a Novel Calcium-Free Lactate Buffered Dialysis and Substitution Fluid for Regional Citrate Anticoagulation - Prospective Feasibility Study

“…Besides a mildly higher lactate load in CVVHDF there were no clinically important differences between the modalities confirming similar impact of diffusive and convective membrane transfer on small molecules with a sieving coefficient about 1.0 [7,18]. Higher gain of lactate in CVVHDF could be explained by the countercurrent effect of dialysis fluid plus significant postdilution [3,7]. …”

“…The aim of calorimetry was to compare the impact of citrate and lactate on oxygen consumption (VO 2 ) and CO 2 production, RQ and energy expenditure (EE) [13]. The bioenergetic gains of citrate and lactate [3,7] as well as loss of glucose were quantified at 9-hour intervals. All patients received a standard nutritional regimen of 3 g/kg/day of glucose, 1.5 g/kg/day of amino acids, and 1 g/kg/day of fat.…”

“…Recently, there is also growing interest in providing exogenous lactate as a metabolic substrate with positive impact on cardiac performance [4]. Lactate buffer in combination with RCA had been used previously [3,5,6,7] as a combination of ordinary calcium containing lactate-buffered bags with less concentrated citrate solution (2.2% Acid-Citrate-Dextrose). The presence of calcium in the dialysis/substitution fluid neutralises the citrate that is already present in the proximal blood set, unnecessarily increasing the requirements for citrate, its systemic load and side effects, and causes shorter filter life compared to calcium-free fluid [3].…”