[Regional citrate anticoagulation in renal replacement therapy in the intensive care station : Recommendations from the renal section of the DGIIN, ÖGIAIN and DIVI]

Let's stop talking about 'citrate toxicity'

PURPOSE OF REVIEW

Continuous renal replacement therapy (CRRT) is a vital medical intervention used in critically ill patients with acute kidney injury (AKI). One of the key components of adequate clearance with CRRT is the use of anticoagulants to prevent clotting of the extracorporeal circuit. Regional citrate anticoagulation is the most often recommended modality. The term 'citrate toxicity' is used to describe potential adverse effects of accumulation of citrate and subsequent hypocalcemia. However, citrate is itself not inherently toxic. The term and diagnosis of citrate toxicity are questioned in this review.

RECENT FINDINGS

Citrate is being increasingly used for regional anticoagulation of the CRRT circuit. Citrate accumulation is infrequent and can cause hypocalcemia and metabolic alkalosis, which are potential adverse effects. Citrate itself, however, is not a toxic molecule. The term 'citrate toxicity' has been used to denote hypocalcemia and metabolic acidosis. However, citrate administration is well known to cause systemic and urinary alkalinization and under certain circumstances, metabolic alkalosis, but is not associated itself with any 'toxic' effects.We review the existing literature and debunk the perceived toxicity of citrate. We delve into the metabolism and clearance of citrate and question current data suggesting metabolic acidosis occurs as the result of citrate accumulation.

SUMMARY

In conclusion, this article calls into question prevailing concerns about 'citrate toxicity'. We emphasize the need for a more nuanced understanding of its safety profile. We recommend discarding the term 'citrate toxicity' in favor of another frequently used, but more meaningful term: 'citrate accumulation'.

Application of regional citrate anticoagulation in patients at high risk of bleeding during intermittent hemodialysis: a prospective multicenter randomized controlled trial

OBJECTIVES

Safe and effective anticoagulation is essential for hemodialysis patients who are at high risk of bleeding. The purpose of this trial is to evaluate the effectiveness and safety of two-stage regional citrate anticoagulation (RCA) combined with sequential anticoagulation and standard calcium-containing dialysate in intermittent hemodialysis (IHD) treatment.

METHODS

Patients at high risk of bleeding who underwent IHD from September 2019 to May 2021 were prospectively enrolled in 13 blood purification centers of nephrology departments, and were randomly divided into RCA group and saline flushing group. In the RCA group, 0.04 g/mL sodium citrate was infused from the start of the dialysis line during blood draining and at the venous expansion chamber. The sodium citrate was stopped after 3 h of dialysis, which was changed to sequential dialysis without anticoagulant. The hazard ratios for coagulation were according to baseline.

RESULTS

A total of 159 patients and 208 sessions were enrolled, including RCA group (80 patients, 110 sessions) and saline flushing group (79 patients, 98 sessions). The incidence of severe coagulation events of extracorporeal circulation in the RCA group was significantly lower than that in the saline flushing group (3.64% vs. 20.41%, P<0.001). The survival time of the filter pipeline in the RCA group was significantly longer than that in the saline flushing group ((238.34±9.33) min vs. (221.73±34.10) min, P<0.001). The urea clearance index (Kt/V) in the RCA group was similar to that in the saline flushing group with no statistically significant difference (1.12±0.34 vs. 1.08±0.34, P=0.41).

CONCLUSIONS

Compared with saline flushing, the two-stage RCA combined with a sequential anticoagulation strategy significantly reduced extracorporeal circulation clotting events and prolonged the dialysis time without serious adverse events.

[Present practise patterns of renal replacement therapy in German intensive care medicine]

About 50% of all critically ill patients develop acute kidney injury (AKI) and approximately 15% receive renal replacement therapy (RRT). Although RRT is frequently used in intensive care units in Germany, it is currently unknown which RRT procedures are available, which qualification the involved staff has, which anticoagulation strategies are used and how RRT doses are prescribed. To investigate quality and structural characteristics of the performance of RRT in intensive care units throughout Germany, the German Interdisciplinary Society of Intensivists (Deutsche Interdisziplinäre Vereinigung für Intensiv- und Notfallmedizin [DIVI]) performed an inquiry among their members. A total of 897 members participated in the survey in which practical aspects were queried. In 69.1% of the cases, RRT was performed in hospitals with more than 400 beds and in 74.5% in university hospitals or other primary care hospitals. Furthermore, 93.3% of clinics are equipped with continuous and 75.8% with intermittent renal replacement devices. In 91.9%, indication for initiation of RRT was performed by trained physicians specialized in intensive care medicine or nephrologists. Intermittent as well as continuous modalities are both present in three-quarters of cases, which allows for individualized therapy. However, the documentation of dialysis dose needs to be improved.

Low bicarbonate replacement fluid normalizes metabolic alkalosis during continuous veno-venous hemofiltration with regional citrate anticoagulation

Background

Metabolic alkalosis is a frequently occurring problem during continuous veno-venous hemofiltration (CVVH) with regional citrate anticoagulation (RCA). This study aimed to evaluate the effectiveness of switching from high to low bicarbonate (HCO₃⁻) replacement fluid in alkalotic critically ill patients with acute kidney injury treated by CVVH and RCA.

Methods

A retrospective-comparative study design was applied. Patients who underwent CVVH with RCA in the ICU between 09/2016 and 11/2017 were evaluated. Data were available from the clinical routine. A switch of the replacement fluid Phoxilium^® (30 mmol/l HCO₃⁻) to Biphozyl^® (22 mmol/l HCO₃⁻) was performed as blood HCO₃⁻ concentration persisted ≥ 26 mmol/l despite adjustments of citrate dose and blood flow. Data were collected from 72 h before the switch of the replacement solutions until 72 h afterwards.

Results

Of 153 patients treated with CVVH during that period, 45 patients were switched from Phoxilium^® to Biphozyl^®. Forty-two patients (42 circuits) were available for statistical analysis. After switching the replacement fluid from Phoxilium^® to Biphozyl^® the serum HCO₃⁻ concentration decreased significantly from 27.7 mmol/l (IQR 26.9–28.9) to 25.8 mmol/l (IQR 24.6–27.7) within 24 h (p < 0.001). Base excess (BE) decreased significantly from 4.0 mmol/l (IQR 3.1–5.1) to 1.8 mmol/l (IQR 0.2–3.4) within 24 h (p < 0.001). HCO₃⁻ and BE concentration remained stable from 24 h till the end of observation at 72 h after the replacement fluid change (p = 0.225). pH and PaCO₂ did not change significantly after the switch of the replacement fluid until 72 h.

Conclusions

This retrospective analysis suggests that for patients developing refractory metabolic alkalosis during CVVH with RCA the use of Biphozyl^® reduces external HCO₃⁻ load and sustainably corrects intracorporeal HCO₃⁻ and BE concentrations. Future studies have to prove whether correcting metabolic alkalosis during CVVH with RCA in critically ill patients is of relevance in terms of clinical outcome.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-021-00850-4.

[Long-term outcome after dialysis-dependent renal failure on the intensive care unit]

Hintergrund

Das akute dialysepflichtige Nierenversagen („dialysis-requiring acute kidney injury“ [AKI‑D]) ist eine häufige und schwerwiegende Komplikation bei intensivmedizinisch behandelten Patienten.

Fragestellung

Im Rahmen dieser Studie sollte untersucht werden, welchen Einfluss ein AKI‑D auf die Sterblichkeit von Intensivpatienten besitzt, bei welchem Anteil der überlebenden Patienten auch bei Entlassung noch ein Nierenersatzverfahren benötigt wird und wie sich dies auf die Langzeitmortalität und die längerfristige Notwendigkeit einer Dialysetherapie auswirkt.

Material und Methoden

Auswertung von 118 Patientenfällen mit AKI‑D zwischen November 2016 und Dezember 2017 auf einer internistischen Intensivstation am Universitätsklinikum Tübingen. Die Dialysefreiheit zum Entlasszeitpunkt und die 1‑Jahres-Mortalität wurden als primäre Endpunkte definiert. Den sekundären Endpunkt stellte die Dialysepflichtigkeit nach 18 Monaten dar.

Ergebnisse

Die Krankenausmortalität der Patienten mit AKI‑D betrug 45,8 % (54/118). Von den 64 überlebenden Patienten mit AKI‑D waren 41 (64,1 %) zum Zeitpunkt der Entlassung nicht mehr auf ein Nierenersatzverfahren angewiesen. Im Vergleich dazu war die 1‑Jahres-Mortalität bei den 23 (35,9 %) Patienten, bei denen zur Krankenhausentlassung noch eine Dialysepflicht bestand, signifikant höher (24,4 % vs. 60,9 %, p = 0,004). Eine Dialysepflichtigkeit 18 Monate nach Krankenhausentlassung bestand bei 7 Patienten (10,9 %). Zu diesem Zeitpunkt waren überwiegend noch Patienten von einer Dialyse abhängig, bei denen bereits zum Entlasszeitpunkt ein Nierenersatzverfahren notwendig war (71,4 % vs. 7,1 %, p = 0,001).

Schlussfolgerungen

Schwere AKI-Episoden, bei denen ein Nierenersatzverfahren auf einer Intensivstation notwendig wird, sind auch 1 Jahr bzw. 18 Monate nach Entlassung mit einer erhöhten Mortalität bzw. einer anhaltenden Dialysepflichtigkeit assoziiert.

Hemofiltration in Patients with Severe Acute Pancreatitis (Review)

Questions regarding the application of extracorporeal detoxification to patients with severe acute pancreatitis have been considered. Hemodialysis, the historically first method of extracorporeal detoxification for such patients, has been also described in the review. Appropriateness of using renal replacement therapy methods and among them continued renal replacement therapy has been shown. Hemofiltration and hemodiafiltration technologies are described in detail including different modes of their application and the possibility of using various types of filters. Available data on hemofiltration for patients with severe acute pancreatitis have been analyzed. Great attention is paid to the unsolved aspects of hemofiltration in severe acute pancreatitis such as determining renal and extrarenal indices; time of starting hemofiltration; selection of volume replacement modes and a buffer system; procedure duration; anticoagulation measures, defining criteria to assess the adequacy of hemofiltration, state severity, and organ dysfunction degree. Further multicenter investigations are necessary to be able to assess the efficacy of the hemofiltration procedures on the basis of the thoroughly worked out and pathogenically grounded protocol using adequate control methods taking into consideration endogenic intoxication phases and intensity of the multiple organ failure syndrome.

[Renal replacement therapy in acute kidney injury : From the indications to cessation]

BACKGROUND

The incidence of acute kidney injury (AKI) has increased over the last decades. Renal replacement therapy (RRT) is increasingly being used. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines define AKI by serum creatinine (SCr) elevation and decrease in urinary output (UO) and suggest prevention strategies and recommendations on the management of RRT. Treatment options are limited and RRT remains the gold standard as supportive treatment but implies a substantial escalation of treatment. With respect to the indications and management of RRT, there are only a few evidence-based recommendations.

OBJECTIVE

This review summarizes the clinical relevance of AKI and presents the most important aspects on the indications and implementation of RRT.

MATERIAL AND METHODS

The available evidence is summarized based on the current literature.

RESULTS

Implementation of the KDIGO bundles to prevent AKI in high-risk patients reduces the incidence of AKI. In the absence of absolute indications, the evidence-based recommendations on when to initiate RRT are limited and controversial. Intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT) procedures can be considered as complementary therapeutic strategies. The CRRT is recommended in hemodynamically unstable patients. Regional citrate anticoagulation is the recommended anticoagulation in CRRT. The optimal effluent dose is effectively 20-25 ml/kg body weight and hour. Spontaneous diuresis is a best predictor of successful cessation of RRT.

CONCLUSION

Risk identification and prevention of AKI are essential. In the absence of absolute indications, initiation and accomplishment of RRT should be patient-adapted and carried out in the clinical context. Newly developed biomarkers could be helpful in the future for a better estimation of the prognosis and for a more precise definition of therapeutic strategies of RRT.