Regional citrate anticoagulation for renal replacement therapies in patients with acute kidney injury: a position statement of the Work Group “Renal Replacement Therapies in Critically Ill Patients” of the Italian Society of Nephrology

Citrate and low-dose heparin combined anticoagulation in pediatric continuous renal replacement therapy

There remains no optimal anticoagulation protocol for continuous renal replacement therapy (CRRT) with regional citrate anticoagulation (RCA) in pediatric patients with elevated D-dimer levels. We aimed to assess the effects of different anticoagulation strategies on the risk of CRRT filter clotting in these patients. Pediatric patients undergoing CRRT were retrospectively grouped based on pre-CRRT D-dimer levels and anticoagulant: D-RCA group (normal D-dimer, RCA only, n = 22), D+ RCA group (elevated D-dimer, RCA only, n = 50), and D+ RCA+ systemic heparin anticoagulation (SHA) group (elevated D-dimer, RCA combined with SHA, n = 55). The risk of filter clotting and incidence of bleeding were compared among the groups. Among the groups, the D+ RCA+ SHA group had the longest filter lifespan; further, the incidence of bleeding was not increased by concurrent use of low-dose heparin for anticoagulation. Moreover, concurrent heparin anticoagulation was associated with a decreased risk of filter clotting. Contrastingly, high pre-CRRT hemoglobin and D-dimer levels and post-filter ionized calcium level > 0.4 mmol/L were associated with an increased risk of filter clotting. RCA combined with low-dose heparin anticoagulation could reduce the risk of filter clotting and prolong filter lifespan without increasing the risk of bleeding in patients with elevated D-dimer levels undergoing CRRT.

Citrate anticoagulation in plasma exchange followed by continuous renal replacement therapy in critically ill children

OBJECTIVE

To investigate the effectiveness and safety of regional citrate-anticoagulated (RCA) plasma exchange (PE) and whether citrate-related metabolic disorders can be improved by sequential RCA continuous renal replacement therapy (CRRT).

METHODS

This retrospective, single-center observational study included 79 critically ill children requiring PE followed by CRRT (June 2018 to June 2021) at the Pediatric Intensive Care Unit of Hunan Children's Hospital, China. Patients were divided into the RCA-PE (n = 30) and systemic heparin anticoagulation (SHA-PE) (n = 49) groups. Filter level comparison post-PE assessed RCA-PE efficacy, and metabolic changes occurring pre- and post-PE and CRRT were used to evaluate the effect of CRRT on RCA-based anticoagulation safety.

RESULTS

The RCA-PE group had a better overall filter performance than the SHA-PE group. Two hours after PE, pH and HCO₃- levels increased more significantly for the RCA-PE than the SHA-PE group. The RCA-PE incidence of metabolic alkalosis was 48.3%, higher by 4.2% (p < 0.001) compared to the SHA-PE group. In the RCA-PE group, pH and HCO₃- decreased significantly 4 h after CRRT; the metabolic alkalosis caused by RCA-PE decreased to 13.8% (p = 0.005). No significant difference in pH, HCO₃-, and metabolic alkalosis incidence was observed between the two groups 4 h after CRRT.

CONCLUSIONS

The overall filtration performance of RCA-PE is superior to that of SHA-PE followed by CRRT. The metabolic complications associated with RCA-PE are mainly metabolic alkalosis that can be improved by using CRRT after RCA-PE and this is a better alternative for anticoagulation during PE in critically ill children.

Comparison of diluted vs concentrated regional citrate anticoagulation in continuous renal replacement therapy: A quasi-experimental study

BACKGROUND

The incidence of coagulation of continuous renal replacement therapy circuits remains high. To the best of our knowledge, no scholar has published a protocol to avoid management errors when different types of citrates coexist in the same Intensive Care Unit.

AIM

To assess the safety and efficacy of the unification of two protocols with different concentrations of citrate solution.

STUDY DESING

A prospective, quasi-experimental study was carried out in the intensive care unit of a tertiary referral hospital (in Barcelona, Spain), over 3 years. Consecutive adult patients requiring continuous renal replacement therapy with citrate were included. The sample was divided into two groups, a control group (concentrated citrate) and an intervention group (diluted citrate). The decision to initiate anticoagulation with diluted (18 mmol/L) or concentrated (136 mmol/L) citrate was made based on the machine available and the decision of the doctor responsible for the patient. It was not possible to randomize the sample. Both protocols were matched with a starting citrate dose of 3.5 mmol/L, and a dialysis solution was used. Post-filter replacement was not used, and the citrate solution was the only fluid administered pre-filter.

RESULTS

The analysis included 59 circuits in the concentrated citrate group and 40 circuits in the diluted citrate group. An increased need for electrolyte replacement was observed in the diluted group (p < .001). The concentrated citrate group had a longer filter life (p < .05), and there was a slight trend toward alkalosis.

CONCLUSION

The diluted citrate group had a higher incidence of electrolyte replacement. The concentrated citrate group had longer circuit lifespan and a trend toward metabolic alkalosis, although this was not statistically significant. If these conclusions are considered, the protocol can be unified.

RELEVANCE TO CLINICAL PRACTICE

The present work aims to provide information on the differences in the use of regional anticoagulation with diluted or concentrated citrate. The objective is to pay special attention to aspects that can lead to complications. The unified protocol proposed in this paper could be extrapolated to any machine on the market that uses either of these two types of citrate concentration.

Calcium-Citrate Anticoagulation during Continuous Renal Replacement Therapy in Patients with Metformin Intoxication: A Case Series, Mathematical Estimation of Citrate Accumulation, and Literature Review

INTRODUCTION

Metformin intoxication causes lactic acidosis by inhibiting Krebs' cycle and oxidative phosphorylation. Continuous renal replacement therapy (CRRT) is recommended for metformin removal in critically ill patients. According to current guidelines, regional citrate anticoagulation (RCA) is the first-line strategy. However, since metformin also inhibits citrate metabolism, a risk of citrate accumulation could be hypothesized. In the present study, we monitored the potential citrate accumulation in metformin-associated lactic acidosis (MALA) patients treated with CRRT and RCA using the physical-chemical approach to acid-base interpretation.

METHODS

We collected a case series of 3 patients with MALA. Patients were treated with continuous venovenous hemofiltration (CVVH), and RCA was performed with diluted citrate solution. Citrate accumulation was monitored through two methods: the ratio between total and ionized plasma calcium concentrations (T/I calcium ratio) above 2.5 and the strong ion gap (SIG) to identify an increased concentration of unmeasured anions. Lastly, a mathematical model was developed to estimate the expected citrate accumulation during CVVH and RCA.

RESULTS

All 3 patients showed a resolution of MALA after the treatment with CVVH. The T/I calcium ratio was consistently below 2.5, and SIG decreased, reaching values lower than 6 mEq/L after 48 h of CVVH treatment. According to the mathematical model, the estimated SIG without citrate metabolism should have been around 21 mEq/L due to citrate accumulation.

CONCLUSIONS

In our clinical management, no signs of citrate accumulation were recorded in MALA patients during treatment with CVVH and RCA. Our data support the safe use of diluted citrate to perform RCA during metformin intoxication.

Metabolic and nutritional aspects in continuous renal replacement therapy

Nutrition is one of the foundations for supporting and treating critically ill patients. Nutritional support provides calories, protein, electrolytes, vitamins, and trace elements via the enteral or parenteral route. Acute kidney injury (AKI) is a common and devastating problem in critically ill patients and has significant metabolic and nutritional consequences. Moreover, renal replacement therapy (RRT), whatever the modality used, also profoundly impacts metabolism. RRT and of the extracorporeal circuit impede 'effect the evaluation of a patient's energy requirements by clinicians. Substrates added and removed within the extracorporeal treatment are not always taken into consideration, making treatment even more challenging. Furthermore, evidence on nutritional support during continuous renal replacement therapy (CRRT) is scarce, and there are no clinical guidelines for nutrition adaptations during CRRT in critically ill patients. Most recommendations are based on expert opinions. This review discusses the complex interaction between nutritional support and CRRT and presents some milestones for nutritional support in critically ill patients on CRRT.

Regional Citrate Anticoagulation in Continuous Renal Replacement Therapy: Is Metabolic Fear the Enemy of Logic? A Systematic Review and Meta-Analysis of Randomised Controlled Trials

BACKGROUND

Anticoagulation is recommended to maintain the patency of the circuit in continuous renal replacement therapy (CRRT). However, anticoagulation-associated complications can occur. We performed a systematic review and meta-analysis to compare the efficacy and safety of citrate anticoagulation to heparin anticoagulation in critically ill patients treated with CRRT.

METHODS

Randomised controlled trials (RCTs) evaluating the safety and efficacy of citrate anticoagulation and heparin in CRRT were included. Articles not describing the incidence of metabolic and/or electrolyte disturbances induced by the anticoagulation strategy were excluded. The PubMed, Embase, and MEDLINE electronic databases were searched. The last search was performed on 18 February 2022.

RESULTS

Twelve articles comprising 1592 patients met the inclusion criteria. There was no significant difference between the groups in the development of metabolic alkalosis (RR = 1.46; (95% CI (0.52-4.11); p = 0.470)) or metabolic acidosis (RR = 1.71, (95% CI (0.99-2.93); p = 0.054)). Patients in the citrate group developed hypocalcaemia more frequently (RR = 3.81; 95% CI (1.67-8.66); p = 0.001). Bleeding complications in patients randomised to the citrate group were significantly lower than those in the heparin group (RR 0.32 (95% CI (0.22-0.47); p < 0.0001)). Citrate showed a significantly longer filter lifespan of 14.52 h (95% CI (7.22-21.83); p < 0.0001), compared to heparin. There was no significant difference between the groups for 28-day mortality (RR = 1.08 (95% CI (0.89-1.31); p = 0.424) or 90-day mortality (RR 0.9 (95% CI (0.8-1.02); p = 0.110).

CONCLUSION

regional citrate anticoagulation is a safe anticoagulant for critically ill patients who require CRRT, as no significant differences were found in metabolic complications between the groups. Additionally, citrate has a lower risk of bleeding and circuit loss than heparin.

Regional citrate anticoagulation (RCA) in critically ill patients undergoing renal replacement therapy (RRT): expert opinion from the SIAARTI-SIN joint commission

Renal replacement therapies (RRT) are essential to support critically ill patients with severe acute kidney injury (AKI), providing control of solutes, fluid balance and acid-base status. To maintain the patency of the extracorporeal circuit, minimizing downtime periods and blood losses due to filter clotting, an effective anticoagulation strategy is required.Regional citrate anticoagulation (RCA) has been introduced in clinical practice for continuous RRT (CRRT) in the early 1990s and has had a progressively wider acceptance in parallel to the development of simplified systems and safe protocols. Main guidelines on AKI support the use of RCA as the first line anticoagulation strategy during CRRT in patients without contraindications to citrate and regardless of the patient's bleeding risk.Experts from the SIAARTI-SIN joint commission have prepared this position statement which discusses the use of RCA in different RRT modalities also in combination with other extracorporeal organ support systems. Furthermore, advise is provided on potential limitations to the use of RCA in high-risk patients with particular attention to the need for a rigorous monitoring in complex clinical settings. Finally, the main findings about the prospective of optimization of RRT solutions aimed at preventing electrolyte derangements during RCA are discussed in detail.

Calcium-containing versus calcium-free replacement solution in regional citrate anticoagulation for continuous renal replacement therapy: a randomized controlled trial

BACKGROUND

A simplified protocol for regional citrate anticoagulation (RCA) using a commercial calcium-containing replacement solution, without continuous calcium infusion, is more efficient for use in continuous renal replacement therapy (CRRT). We aim to design a randomized clinical trial to compare the safety and efficacy between calcium-free and calcium-containing replacement solutions in CRRT with RCA.

METHODS

Of the 64 patients receiving RCA-based postdilution continuous venovenous hemodiafiltration (CVVHDF) enrolled from 2017 to 2019 in West China Hospital of Sichuan University, 35 patients were randomized to the calcium-containing group and 29 to the calcium-free replacement solution group. The primary endpoint was circuit lifespan and Kaplan-Meier survival analysis was performed. Secondary endpoints included hospital mortality, kidney function recovery rate, and complications. The amount of 4% trisodium citrate solution infusion was recorded. Serum and effluent total (tCa) and ionized (iCa) calcium concentrations were measured during CVVHDF.

RESULTS

A total of 149 circuits (82 in the calcium-containing group and 67 in the calcium-free group) and 7609 circuit hours (4335 h vs. 3274 h) were included. The mean circuit lifespan was 58.1 h (95% CI 53.8-62.4 h) in the calcium-containing group vs. 55.3 h (95% CI 49.7-60.9 h, log rank P = 0.89) in the calcium-free group. The serum tCa and iCa concentrations were slightly lower in the calcium-containing group during CRRT, whereas the postfilter iCa concentration was lower in the calcium-free group. Moreover, the mean amounts of 4% trisodium citrate solution infusion were not significantly different between the groups (171.1 ± 15.9 mL/h vs. 169.0 ± 15.1 mL/h, P = 0.49). The mortality (14/35 [40%] vs. 13/29 [45%], P = 0.70) and kidney function recovery rates of AKI patients (19/26, 73% vs. 14/24, 58%, P = 0.27) were comparable between the calcium-containing and calcium-free group during hospitalization, respectively. Six (three in each group) patients showed signs of citrate accumulation in this study.

CONCLUSIONS

When compared with calcium-free replacement solution, RCA-based CVVHDF with calcium-containing replacement solution had a similar circuit lifespan, hospital mortality and kidney outcome. Since the calcium-containing solution obviates the need for a separate venous catheter and a large dose of intravenous calcium solution preparation for continuous calcium supplementation, it is more convenient to be applied in RCA-CRRT practice.

REGISTRATION

Chinese Clinical Trial Registry (www.chictr.org.cn, ChiCTR-IPR-17012629).

Comparison of different modalities of continuous renal replacement therapy with regional sodium citrate anticoagulation in paediatric patients

BACKGROUND

To evaluate the efficacy and safety of continuous renal replacement therapy (CRRT) modalities with regional sodium citrate anticoagulation (RCA) in children.

METHODS

This retrospective study was conducted at the paediatric intensive care unit of Hunan Children's Hospital in China. Medical records of paediatric patients hospitalised for RCA-CRRT between April 2017 and March 2021 were reviewed. Patients received continuous venovenous haemodialysis, continuous venovenous haemofiltration (CVVH), or continuous venovenous haemodiafiltration (CVVHDF).

RESULTS

Patients on continuous venovenous haemodialysis (n = 2) were excluded because of their small sample size. The remaining participants were divided into CVVH and CVVHDF groups; 80 patients received CRRT, with 40 and 62 sessions in the CVVH and CVVHDF groups, respectively. The filtre lifespan was longer in the CVVHDF group than in the CVVH group (median value [interquartile range]; 47 [15] hours vs. 35 [17.5] hours; p = 0.029). Compared with the CVVHDF group, the hazard ratio for filtre lifespan in the CVVH group was 3.023 (95% confidence interval 1.820-5.023, p < 0.001). There were no significant differences in ionised calcium levels of the circuits between the two groups at different time points (p < 0.05). Metabolic alkalosis, hyperlactataemia, hypocalcaemia, and hypercalcaemia occurred in both groups, with metabolic alkalosis being the most common complication. No patients in either group experienced sodium citrate accumulation or hypernatraemia. Inter-group differences in the incidence of these complications were not statistically significant (p > 0.05).

CONCLUSIONS

Our results suggest that CVVHDF is a better option for RCA-CRRT than CVVH.

Continuous Renal Replacement Therapy in Pediatric Patients With Acute Kidney Injury After Liver Transplantation

Objective

This study aimed to explore the clinical application of continuous renal replacement therapy (CRRT) in pediatric patients with acute kidney injury (AKI) after liver transplantation.

Methods

Pediatric patients who underwent liver transplantation were retrospectively investigated. Those who developed AKI within 1 year after the surgery were included and divided into a CRRT group and a non-CRRT group. The perioperative conditions and postoperative complications of the two groups were compared along with the prognoses of the groups to analyze the high-risk factors of the postoperative CRRT.

Results

189 (36.91%) patients developed AKI within 1 year after the liver transplantation surgery. There were 18 patients in the CRRT group and 171 in the non-CRRT group. The differences in the preoperative conditions were not statistically significant between the two groups. Compared with the non-CRRT group, patients in the CRRT group had significantly longer transplantation times, higher volumes of intraoperative hemorrhage, and increased incidence of postoperative unscheduled surgery, postoperative primary nonfunction of the transplanted liver, secondary liver transplantation, hepatic artery occlusion, and intestinal fistula (P < 0.05). Moreover, the proportion of patients in AKI stage 3 is higher in the CRRT group (83.33%) than that in the non-CRRT group (11.11%), P < 0.001. The median time to initiate CRRT was 10 days postoperatively, the median number of CRRT treatments per patient was 2 times, the average duration of each CRRT treatment was 10.1 h, and the average rate of the decrease in blood creatinine per treatment was 25.6%. Results of multivariate logistic regression analysis showed that AKI stage 3 [OR=40.000, 95%CI (10.598, 150.969), P = 0.016], postoperative unscheduled surgery [OR=6.269, 95%CI (3.051, 26.379), P = 0.007], and hepatic artery occlusion [OR = 17.682, 95%CI (1.707, 40.843), P = 0.001] were recognized as risk factors for postoperative AKI with CRRT therapy. The one- and two-year survival rates were 72.22% and 72.22% in the CRRT group, respectively; and 97.08% and 96.49% in the non-CRRT group, accordingly. There were statistically significant differences in the one- and two-year survival rates between the two groups (P < 0.001).

Conclusion

The incidence of AKI after liver transplantation in pediatric patients was high. Patients with AKI stage 3, hepatic artery occlusion, and underwent unscheduled surgery postoperatively were with a high likelihood of receiving CRRT, which was related to a lower one- and two-year survival rates. CRRT effectively improved the one- and two-year survival rates.

Colistin Therapy, Survival and Renal Replacement Therapy in Burn Patients: A 10-Year Single-Center Cohort Study

Purpose

Patients and Methods

Results

Conclusion

Heparin-free regional anticoagulation of haemodialysis filters with calcium-free dialysate: is citrate mandatory?

Background

There is an unmet need to develop safe and successful heparin-free regional anticoagulation modalities in haemodialysed patients at risk of bleeding. Whether the addition of citrate as a prefilter injection or in the dialysate itself is required to reach anticoagulation objectives when calcium-free dialysate is used as regional anticoagulation remains unclear.

Methods

In this monocentric retrospective study, we report our experience of 908 dialysis sessions performed with a calcium-free citrate-containing dialysate and calcium reinjection according to the ionic dialysance, without additional heparin.

Results

Premature termination for filter clotting occurred in 20 sessions (2.2%) and duration of session was >4.5 h in 135 (15%; maximum duration 6 h). In addition, we could investigate the citrate, calcium and acid–basis status during haemodialysis sessions performed with (citrate group, n = 20 sessions) or without (citrate-free group, n = 19 sessions) citrate in the dialysate. In 20 sessions performed in patients with underlying liver disorders and using calcium-free citrate-containing dialysate, patients’ ionized calcium (iCa) and serum citrate levels were stable and remained within the normal range, respectively. Post-filter iCa was below 0.4 mmol/L in 19/20 sessions and citrate was 0.304 mmol/L (range: 0.011; 0.548). In 19 sessions that used calcium and citrate-free dialysate, post-filter iCa was 0.41 mmol/L (0.34; 0.5) and all sessions extended to 4 h or beyond.

Conclusions

Regional anticoagulation of haemodialysis with a calcium-free dialysate and calcium reinjection according to the ionic dialysance is safe. Adding citrate to the dialysate is not mandatory to prevent dialysis circuit clotting in most patients.

A simplified protocol for individualized regional citrate anticoagulation for hemodialysis: A single-center, randomized clinical study

INTRODUCTION

The lack of individualized treatment protocols and complicated procedures are important factors limiting the use of regional citrate anticoagulation (RCA) technology in hemodialysis. This study aims to validate the safety and efficacy of a simplified individualized RCA protocol for hemodialysis.

MATERIALS AND METHODS

From June 2019 to August 2019, 45 patients with active bleeding or bleeding tendency undergoing maintenance hemodialysis in the Nephrology Department of the First Affiliated Hospital of Nanchang University were randomly divided into a modified conventional RCA protocol group with a low-flux dialyzer, a simplified individualized RCA protocol group with a high-flux dialyzer, and a simplified individualized RCA protocol group with a low-flux dialyzer.

RESULTS

A total of 45 patients were included in this study. The mean age of the patients was 57.38 ± 19.05 years, and 78% were men. Forty-three patients completed 4 hours of hemodialysis, and the median total clotting scores in the 3 groups were 11, 12, and 12. Compared with the modified conventional RCA protocol group with a low-flux dialyzer, the 2 simplified individualized RCA protocol groups had better clotting scores for the dialyzer, arterial bubble trap, and single-pool urea clearance index (spKt/VBUN) and lower costs. Moreover, these parameters did not differ between the 2 simplified individualized RCA protocol groups. No electrolyte or acid-base imbalances or citrate poisoning was observed in any of the 3 groups. Adverse events did not differ significantly among the 3 groups.

CONCLUSIONS

The simplified individualized RCA protocol is safe, effective, and easy to implement. Therefore, this protocol can be promoted for clinical practice.

TRIAL REGISTRATION

This study was registered in the Chinese Clinical Study Registry under registration number ChiCTR1900023801.

Citrate high volume on-line hemodiafiltration modulates serum Interleukin-6 and Klotho levels: the multicenter randomized controlled study "Hephaestus"

BACKGROUND

Studies addressing the anti-inflammatory properties of citrate dialysate enrolled patients in both hemodialysis (HD) and hemodiafiltration (HDF), the latter not adjusted for adequate convective exchange. This is a potential source of confounding in that HDF itself has anti-inflammatory effects regardless of the buffer, and optimal clinical outcomes are related to the amount of convection.

METHODS

To distinguish the merits of the buffer from those of convection, we performed a 6-month, prospective, randomized, crossover AB-BA study. Comparisons were made during the 3-month study period of on-line HDF with standard dialysate containing three mmol of acetic acid (OL-HDFst) and the 3-month of OL-HDF with dialysate containing one mmol of citric acid (OL-HDFcit). Primary outcome measure of the study was interleukin-6 (IL-6). Klotho, high sensitivity C-reactive protein (hsCRP), fetuin and routine biochemical parameters were also analyzed.

RESULTS

We analyzed 47 patients (mean age 64 years, range 27-84 years) enrolled in 10 participating Nephrology Units. Convective volumes were around 25 L/session with 90 percent of sessions > 20 L and ß2-microglobulin reduction rate 76% in both HDFs. Baseline median IL-6 values in OL-HDFst were 5.6 pg/ml (25:75 interquartile range IQR 2.9:10.6) and in OL-HDFcit 6.6 pg/ml (IQR 3.4:11.4 pg/ml). The difference was not statistically significant (p 0.88). IL-6 values were lower during OL-HDFcit than during OL-HDFst, both when analyzed as the median difference of overall IL-6 values (p 0.02) and as the median of pairwise differences between the baseline and the 3-month time points (p 0.03). The overall hsCRP values too, were lower during OL-HDFcit than during OL-HDFst (p 0.01). Klotho levels showed a time effect (p 0.02) and the increase was significant only during OL-HDFcit (p 0.01).

CONCLUSIONS

Citrate buffer modulated IL-6, hsCRP and Klotho levels during high volume OL-HDF. These results are not attributable to differences in the dialysis technology that was applied and may suggest a potential biological effect of citrate on CKD-associated inflammatory state. ClinicalTrials.gov identifier NCT02863016.

Sustained low-efficiency dialysis with regional citrate anticoagulation in critically ill patients with COVID-19 associated AKI: A pilot study

Acute Kidney Injury (AKI) is a frequent complication in critically ill patients with Coronavirus disease 2019 (COVID-19), and it has been associated with worse clinical outcomes, especially when Kidney Replacement Therapy (KRT) is required. A condition of hypercoagulability has been frequently reported in COVID-19 patients, and this very fact may complicate KRT management. Sustained Low Efficiency Dialysis (SLED) is a hybrid dialysis modality increasingly used in critically ill patients since it allows to maintain acceptable hemodynamic stability and to overcome the increased clotting risk of the extracorporeal circuit, especially when Regional Citrate Anticoagulation (RCA) protocols are applied. Notably, given the mainly diffusive mechanism of solute transport, SLED is associated with lower stress on both hemofilter and blood cells as compared to convective KRT modalities. Finally, RCA, as compared with heparin-based protocols, does not further increase the already high hemorrhagic risk of patients with AKI. Based on these premises, we performed a pilot study on the clinical management of critically ill patients with COVID-19 associated AKI who underwent SLED with a simplified RCA protocol. Low circuit clotting rates were observed, as well as adequate KRT duration was achieved in most cases, without any relevant metabolic complication nor worsening of hemodynamic status.

Prevention of hypomagnesemia in critically ill patients with acute kidney injury on continuous kidney replacement therapy: the role of early supplementation and close monitoring

Hypomagnesemia is a common electrolyte disorder in critically ill patients and is associated with increased morbidity and mortality risk. Many clinical conditions may contribute to hypomagnesemia through different pathogenetic mechanisms. In patients with acute kidney injury (AKI) the need for continuous or prolonged intermittent kidney replacement therapy (CKRT and PIKRT, respectively) may further add to other causes of hypomagnesemia, especially when regional citrate anticoagulation (RCA) is used. The basic principle of RCA is chelation of ionized calcium by citrate within the extracorporeal circuit, thus blocking the coagulation cascade. Magnesium, a divalent cation, follows the same fate as calcium; the amount lost in the effluent includes both magnesium-citrate complexes and the free fraction directly diffusing through the hemofilter. While increasing the magnesium content of dialysis/replacement solutions may decrease the risk of hypomagnesemia, the optimal concentration for the variable combination of solutions adopted in different KRT protocols has not yet been identified. An alternative and effective approach is based on including early intravenous magnesium supplementation in the KRT protocol, and close monitoring of serum magnesium levels, especially in the setting of RCA. Thus, strategies aimed at precisely tailoring both dialysis prescriptions and the composition of KRT fluids, as well as early magnesium supplementation and close monitoring, could represent a cornerstone in reducing KRT-related hypomagnesemia.

Albumin Loss and Citrate Load in Pre-Dilution High Cut-Off-CVVHDF with Regional Citrate (18 mmol/L) and High Cut-Off CVVHD with Systemic Heparin: An in vitro Study

BACKGROUND

Convective therapies with high cut-off membranes (HCO) are usually not recommended because of theoretical excessive albumin loss. The aim of this in vitro study is to demonstrate the noninferior safety of pre-dilution hemodiafiltration with HCO (HCO-CVVHDF) with isotonic citrate anticoagulation (18 mmol/L) with respect to heparin anticoagulated hemodialysis with HCO (HCO-CVVHD) in terms of albumin removal and citrate load.

METHOD

-Albumin removal was compared in vitro between 3 pre--dilution-HCO-CVVHDF with citrate anticoagulation and 3 -HCO-CVVHD with heparin anticoagulation during 30-min single-pass and 180-min recirculation phases.

RESULTS

Considering concentrations and flows in the extracorporeal circuit, the transmembrane albumin removal was 2.06 (1.51; 2.09) g and 2.09 (1.9; 2.8) g respectively for HCO-CVVHDF and HCO-CVVHD, during the single-pass phase; 2.8 (2.67; 4.59) g and 2.54 (2.35; 4.67) g, respectively, for HCO-CVVHDF and HCO-CVVHD during the recirculation phase. Based on the citrate saturation coefficients, a citrate metabolic load of 8.86 mmol/h has been calculated for HCO-CVVHDF.

CONCLUSION

HCO-CVVHDF performed with regional anticoagulation with 18 mmol/L citrate solution does not induce higher -albumin transmembrane removal compared to HCO-CVVHD.

Heparin-Free Prolonged Intermittent Hemodialysis Using Calcium-Free Citrate Dialysate in Critically Ill Patients

OBJECTIVES

Critically ill patients who have a high risk of bleeding but require prolonged intermittent dialysis need a heparin-free easy-to-use alternative type of anticoagulation within the dialysis circuit. We assessed the safety and efficiency of heparin-free regional citrate anticoagulation of the dialysis circuit using a calcium-free citrate-containing dialysate, with calcium reinjected according to ionic dialysance.

DESIGN

Prospective cohort study.

SETTING

Critical care units.

PATIENTS

Critically ill patients who required renal replacement therapy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A total of 101 dialysis sessions were performed in 35 patients (mechanical ventilation n = 78; norepinephrine n = 13). Median duration of dialysis was 294 minutes (interquartile range, 240-300), and median ultrafiltration volume was 2.3 L (1-2.8). Urea and β2-microglobulin reduction rates were 64.5% ± 0.4% and 48% ± 0.13%, respectively. Postfilter ionized calcium was 0.35 ± 0.17 and 0.38 ± 0.14 mmol/L at 1 and 3 hours, respectively, within the extracorporeal circuit. A major clotting event that led to premature termination of the session occurred in only three of 101 sessions. In these three cases, major catheter dysfunction occurred before clotting within the circuit. Prefilter ionized calcium remained within narrow ranges (before/after change +0.07 ± 0.006 mmol/L), and total-to-ionized calcium ratio, a surrogate marker for citratemia, was unchanged.

CONCLUSIONS

Dialysis anticoagulation with calcium-free citrate-containing dialysate and calcium reinjection according to ionic dialysance is an easy-to-use, efficient, and inexpensive form of heparin-free regional anticoagulation. It allows prolonged hemodialysis sessions in critically ill patients without the need to systemically monitor ionized calcium. Furthermore, sessions can be safely extended according to the hemodynamic tolerance to ensure an adequate dose of dialysis and a negative water balance, a major point in patients with severe acute kidney disease.

Considerations for Medication Management and Anticoagulation During Continuous Renal Replacement Therapy

Providing safe and high-quality care to critically ill patients receiving continuous renal replacement therapy (CRRT) includes adequate drug dosing and evaluation of patients' response to medications during therapy. Pharmacokinetic drug studies in acute kidney injury and CRRT are limited, considering the number of medications used in critical care. Therefore, it is important to understand the basic principles of drug clearance during CRRT by evaluating drug properties, CRRT modalities, and how they affect medication clearance. Few published studies have addressed drug disposition and clinical response during CRRT. Additionally, clotting in the CRRT circuit is a concern, so a few options for anticoagulation strategies are presented. This article reviews (1) the CRRT system and drug property factors that affect medication management, (2) the evidence available to guide drug dosing, and (3) anticoagulation strategies for critically ill patients receiving CRRT.

Sustained low-efficiency extended dialysis (SLED) with single-pass batch system in critically-ill patients with acute kidney injury (AKI)

BACKGROUND

Single-pass batch dialysis (SBD) is a well-established system for treatment of end-stage renal disease. However, little evidence is available on sustained low-efficiency extended dialysis (SLED) performed with SBD in patients with acute kidney injury (AKI) in the intensive care unit (ICU).

METHODS

All SLED-SBD sessions conducted on AKI patients in nine ICUs between March and June 2010 were retrospectively analyzed regarding the achieved metabolic and fluid control. Logistic regression was performed to identify the risk factors associated with hypotension and clotting during the sessions.

RESULTS

Data from 106 patients and 421 sessions were analyzed. Patients were 54.2 ± 17.0 years old, 51 % males, and the main AKI cause was sepsis (68 %); 80 % of patients needed mechanical ventilation and 55 % vasoactive drugs. Hospital mortality was 62 %. The median session time was 360 min [interquartile range (IQR) 300-360] and prescribed ultrafiltration was 1500 ml (IQR 800-2000). In 272 sessions (65 %) no complications were recorded. No heparin was used in 269/421 procedures (64 %) and system clotting occurred in 63 sessions (15 %). Risk factors for clotting were sepsis [odds ratio (OR) 2.32 (1.31-4.11), p = 0.004], no anticoagulation [OR 2.94 (1.47-5.91), p = 0.002] and the prescribed time (hours) [OR 1.14 (1.05-1.24), p = 0.001]. Hypotension occurred in 25 % of procedures and no independent risk factors were identified by logistic regression. Adequate metabolic and fluid balance was achieved during SLED sessions. Median blood urea decreased from 107 to 63 mg/dl (p < 0.001), potassium from 4.1 to 3.9 mEq/l (p < 0.001), and increased bicarbonate (from 21.4 to 23.5 mEq/l, p < 0.001). Median fluid balance during session days ranged from +1300 to -20 ml/24 h (p < 0.001).

CONCLUSIONS

SLED-SBD was associated with a low incidence of clotting despite frequent use of saline flush, and achieved a satisfactory hemodynamic stability and reasonable metabolic and fluid control in critically-ill AKI patients.