Citrate pathophysiology and metabolism

Platelets isolation and ectonucleotidase assay: Revealing functional aspects of the communication between the vasculature and the immune system

Platelets are enucleated fragments of cells with a diversity of internal granules. They are responsible for functions related to hemostasis, coagulation, and inflammation. The activation of these processes depends on a cascade coordinated by cytokines, chemokines, and components of purinergic signaling, such as ATP, ADP, and adenosine. Platelets express distinct components of the purinergic system: P2X1, P2Y1, PY12, and P2Y14 receptors; and the ectonucleotidases NTPDase, NPP, and 5NTE (ecto-5'-nucleotidase). Except for P2Y14, which has not yet exhibited a known function, all other components relate to the biological processes mentioned before. Platelets are known to display specific responses to microorganisms, being capable of recognizing pathogen-associated molecular patterns (PAMPs), engulfing certain classes of viruses, and participating in NETosis. Platelet function dysregulation implicates various pathophysiological processes, including cardiovascular diseases (CVDs) and infections. In COVID-19 patients, platelets exhibit altered purinergic signaling and increased activation, contributing to inflammation. Excessive platelet activation can lead to complications from thrombosis, which can affect the circulation of vital organs. Therefore, controlling the activation is necessary to end the inflammatory process and restore homeostasis. Ectonucleotidases, capable of hydrolyzing ATP, ADP, and AMP, are of fundamental importance in activating platelets, promising pharmacological targets for clinical use as cardiovascular protective drugs. In this review, we revisit platelet biology, the purinergic receptors and ectonucleotidases on their surface, and their importance in platelet activity. Additionally, we describe methods for isolating platelets in humans and murine, as well as the main techniques for detecting the activity of ectonucleotidases in platelets. Considering the multitude of functions revealed by platelets and their potential use as potent bioreactors able to secrete and present molecules involved in the communication of the vasculature with the immune system, it is crucial to deeply understand platelet biology and purinergic signaling participation to contribute to the developing of therapeutic strategies in diseases of the cardiovascular, inflammatory, and immune systems.

Citrate-Buffered, Magnesium-Enriched Dialysate on Calcification Propensity in Hemodialysis Patients - The CitMag Study

Introduction

Serum calcification propensity (T50 time) is associated with mortality in patients on dialysis. Several solitary interventions improve T50. However, whether a combination of interventions yields further increases in T50 is unknown. We hypothesized that a combination of 2 interventions, namely increasing magnesium concentration while simultaneously substituting acetate for citrate in the dialysis fluid, leads to increases in T50 values.

Methods

In a randomized controlled trial, 60 patients on chronic hemodialysis were allocated to either continue on standard (S) dialysate (3 mmol/l acetate, 0.5 mmol/l magnesium) or a sequence of magnesium-enriched (Mg0.75) dialysate (3 mmol/l acetate, 0.75 mmol/l magnesium) for 2 weeks followed by combination treatment using citrate-buffered, magnesium-enriched (Cit+Mg0.75) dialysate (1 mmol/l citrate, 0.75 mmol/l magnesium) for 3 weeks. The primary end point was the difference in T50 times between the S group and the Cit+Mg0.75 group.

Results

There was no significant difference in T50 time between the S group and the Cit+Mg0.75 group (236 ± 77 vs. 265 ± 97 min, P = 0.23). The size (hydrodynamic radius) of secondary calciprotein particles did not differ between the S group and the Cit+Mg0.75 group (294 ± 95 vs. 309 ± 91 nm, P = 0.56). In longitudinal analyses, serum magnesium concentrations increased from 1.07 ± 0.17 to 1.24 ± 0.17 mmol/l with the Mg0.75 dialysate (P < 0.0001) but decreased again to 1.19 ± 0.16 mmol/l with the Cit+Mg0.75 dialysate (P < 0.0001).

Conclusion

The combination of citrate buffer with increased magnesium concentration in dialysate does not improve T50.

Higher Doses of Calcium Associated With Survival in Trauma Patients

INTRODUCTION

Calcium is required for coagulation, cardiac output, and peripheral vascular resistance. Between 85% and 94% of trauma patients treated with massive blood transfusion develop hypocalcemia.1 The aim of this study is to evaluate the relationship between increased intravenous calcium administration during massive transfusion and improved survival of trauma patients.

METHODS

We performed a retrospective analysis of trauma patients who received massive transfusion over a 2-y period. Doses of elemental calcium administered per unit of blood product transfused were calculated by calcium to blood product ratio (CBR). Chi-square test evaluated association between coagulopathy and 30-d mortality. Two-sample t-test evaluated association between CBR and coagulopathy. Bivariate regression analysis evaluated association between CBR and blood products transfused per patient. Multivariable logistic regression analysis, controlling for age, sex, coagulopathy, and Injury Severity Score evaluated the association between CBR and mortality.

RESULTS

The study included 77 patients. Coagulopathy was associated with increased 30-d mortality (P < 0.05). Patients who survived had higher CBR than those who died (P < 0.05). CBR was associated with a significant reduction in total blood products transfused per patient (P < 0.05). CBR was not associated with coagulopathy (P = 0.24). Multivariable logistic regression analysis demonstrated that Injury Severity Score ≥16, coagulopathy and decreased CBR were significant predictors of mortality (P < 0.05). CBR above 50 mg was a predictor of survival (P < 0.05).

CONCLUSIONS

Higher doses of calcium given per blood product transfused were associated with improved 30-d survival and decreased blood product transfusions.

PROSPECTIVE EXAMINATION OF THE K/ICA RATIO AS A PREDICTOR FOR MORTALITY IN SEVERE HEMORRHAGE

ABSTRACT

Background: Patients receiving massive transfusion protocol (MTP) are at risk for posttransfusion hypocalcemia and hyperkalemia. Previous retrospective analysis has suggested the potassium/ionized calcium (K/iCa) ratio as a prognostic indicator of mortality. This prospective study sought to validate the value of the K/iCa ratio as a predictor for mortality in patients receiving MTP. Methods: This was a prospective analysis of adult trauma patients who underwent MTP activation from May 2019 to March 2021 at an urban level 1 trauma center. Serum potassium and iCa levels within 0 to 1 h of MTP initiation were used to obtain K/iCa. Receiver operator characteristic curve analysis assessed predictive capacity of K/iCa on mortality. Kaplan-Meier survival analysis and Cox regression examined the effect of K/iCa ratio on survival. Results: A total of 110 of 300 MTP activation patients met inclusion criteria. Overall mortality rate was 31.8%. No significant differences between the elevated K/iCa and lower K/iCa groups were found for prehospital or emergency department initial vitals, shock index, or injury severity. However, nonsurvivors had a significantly higher median K/iCa ratio compared with those who survived ( P < 0.01). Multivariable logistic regression revealed the total number of blood products to be significantly associated with elevated K/iCa (odds ratio, 1.02; 95% CI, 1.01-1.04; P = 0.01). The Kaplan Meier survival curve demonstrated a significantly increased rate of survival for those with an elevated K/iCa ratio ( P < 0.01). Multivariable Cox regression adjusted for confounders showed a significant association between K/iCa and mortality (Hazard Ratio, 4.12; 95% CI, 1.89-8.96; P < 0.001). Conclusion: This evidence further highlights the importance of the K/iCa ratio in predicting mortality among trauma patients receiving MTP. Furthermore, it demonstrates that posttransfusion K levels along with iCa levels should be carefully monitored in the MTP setting. Level of Evidence: Level II. Study Type: Prognostic/epidemiological.

First In Vivo Applicational Data of Foam-Based Intrathoracic Chemotherapy (FBiTC) in a Swine Model

BACKGROUND

For decades, both intraperitoneal and pleural chemotherapy (IPC) have been delivered as a liquid solution. Recent studies suggest that foam carriers outperform liquid carriers for locoregional chemotherapy. For the first time, this study aims to evaluate the feasibility, safety, and characteristics of foam-based intrathoracic chemotherapy (FBiTC) in an in vivo setting.

METHODS

In this study, contrast-enhanced FBiTC with doxorubicin was delivered via video-assisted thoracoscopy (VAT) in three swine under general anesthesia. Intraoperative and postoperative parameters, blood analyses, vital signs, and anesthesiologic data were collected. Additionally, an intraoperative computer tomography (CT) scan was performed, and histological tissue sections were collected and further analyzed using fluorescence microscopy.

RESULTS

FBiTC was delivered without major complications. End-tidal capnometry detected increased CO2 levels with reduced peripheral oxygen saturation and increased blood pressure and heart rate. No major intra- or postoperative complications were observed. CT scans confirmed a multidirectional distribution pattern of foam. Postoperative laboratory workup did not reveal any critical changes in hemoglobin, white blood count, or platelets. There was no evidence of critical kidney impairment or liver function. Fluorescence microscopy of tissue specimen detected doxorubicin in pleural tissues.

DISCUSSION

Our preliminary results are encouraging and indicate that FBiTC is feasible. However, to consider a possible clinical application, further studies are required to investigate the pharmacologic, pharmacodynamic, and physical properties of FBiTC and to ensure the safety of the overall procedure regarding oxygenation levels and capnography parameters.

Heparin anticoagulation versus regional citrate anticoagulation for membrane therapeutic plasma exchange in patients with increased bleeding risk

Background Heparin anticoagulation (HA) is commonly employed for membrane therapeutic plasma exchange (mTPE). However, for patients with increased bleeding risk, there were controversial opinions on the use of HA versus regional citrate anticoagulation (RCA) for mTPE. Our present study aimed to evaluate the efficacy and safety of HA vs. RCA for mTPE in patients with increased bleeding risk.Methods Patients with increased bleeding risk who underwent mTPE between 2014 and 2021 in our center were screened. Observations of anticoagulation efficacy and safety were used as the study endpoints.Results A total of 108 patients with 368 mTPE sessions were included. Of the included patients, 38 and 70 received HA and RCA mTPE, respectively. There was no significant difference in the clotting of extracorporeal circuits between the HA and RCA groups (4.1% vs. 4.4%, p = 0.605). More bleeding episodes were observed in the HA group compared to the RCA group (16.4% vs. 4.4% mTPE sessions, p < 0.001). The frequency of postoperative transfusion within 24 h (11% vs. 3.4%, p = 0.007) was significantly different in the HA and RCA group. Anticoagulation strategy (HA vs. RCA; OR 5.659, 95%CI 2.266-14.129; p < 0.001), and mean arterial pressure (prior treatment, OR 1.052, 95%CI 1.019-1.086; p = 0.002) were independent risk factors of bleeding episodes. At the end of mTPE treatment, the incidence of metabolic alkalosis (16.7% vs. 54.1%, p = 0.027) and hypocalcemia (41.7% vs. 89.2%, p = 0.001) was significantly different in the HA (n = 5, 12 sessions) and RCA (n = 22, 74 sessions) groups, respectively.Conclusion RCA is as effective as HA for mTPE. However, for patients with increased bleeding risk, RCA is associated with a lower risk of bleeding, compared with HA. With careful monitoring and timely adjustment, RCA most likely is a safe and effective anticoagulation option for mTPE in patients with increased bleeding risk.

Drug Distribution and Penetration of Foam-Based Intraperitoneal Chemotherapy (FBIC)

For decades, intraperitoneal chemotherapy (IPC) was used as a liquid solution for the treatment of peritoneal metastasis. Due to its advantageous physical properties, foam-based intraperitoneal chemotherapy (FBIC) was recently proposed as a treatment for peritoneal metastasis. For the first time, this study intends to examine the feasibility, expansion, drug distribution, and penetration of FBIC in vivo. Three swine received contrast-enhanced FBIC doxorubicin delivered using a bicarbonate carrier system. During the procedure, intraoperative blood analyses and periumbilical diameter, as well as foam distribution, penetration, and expansion of the FBIC were analyzed. The swine received an abdominal CT scan to evaluate the contrast distribution. Furthermore, a hematoxylin-eosin (HE) staining of peritoneal samples was performed, and fluorescence microscopy was conducted. FBIC was performed without complications. The periumbilical diameter peaked after 5 min and then decreased. Blood analyses showed changes in blood parameters, with a reduction in the pH levels of serum calcium and potassium. CT scan detected contrast-enhanced FBIC throughout the abdominal cavity. Fluorescence microscopy confirmed that all areas were exposed to doxorubicin and no pathologies were detected in the HE histology. Our preliminary results are quite encouraging and indicate that FBIC is a feasible approach. However, in order to discuss possible clinical applications, further studies are required to investigate the pharmacologic, pharmacodynamic, and physical properties of FBIC.

Impact of Transfused Citrate on Pathophysiology in Massive Transfusion

This narrative review article seeks to highlight the effects of citrate on physiology during massive transfusion of the bleeding patient.

DATA SOURCES

A limited library of curated articles was created using search terms including "citrate intoxication," "citrate massive transfusion," "citrate pharmacokinetics," "hypocalcemia of trauma," "citrate phosphate dextrose," and "hypocalcemia in massive transfusion." Review articles, as well as prospective and retrospective studies were selected based on their relevance for inclusion in this review.

STUDY SELECTION

Given the limited number of relevant studies, studies were reviewed and included if they were written in English. This is not a systematic review nor a meta-analysis.

DATA EXTRACTION AND SYNTHESIS

As this is not a meta-analysis, new statistical analyses were not performed. Relevant data were summarized in the body of the text.

CONCLUSIONS

The physiologic effects of citrate independent of hypocalcemia are poorly understood. While a healthy individual can rapidly clear the citrate in a unit of blood (either through the citric acid cycle or direct excretion in urine), the physiology of hemorrhagic shock can lead to decreased clearance and prolonged circulation of citrate. The so-called "Diamond of Death" of bleeding-coagulopathy, acidemia, hypothermia, and hypocalcemia-has a dynamic interaction with citrate that can lead to a death spiral. Hypothermia and acidemia both decrease citrate clearance while circulating citrate decreases thrombin generation and platelet function, leading to ionized hypocalcemia, coagulopathy, and need for further transfusion resulting in a new citrate load. Whole blood transfusion typically requires lower volumes of transfused product than component therapy alone, resulting in a lower citrate burden. Efforts should be made to limit the amount of citrate infused into a patient in hemorrhagic shock while simultaneously addressing the induced hypocalcemia.

Analysis of influencing factors of serum total protein and serum calcium content in plasma donors

Background and objectives

The adverse effects of plasma donation on the body has lowered the odds of donation. The aim of this study was to investigate the prevalence of abnormal serum calcium and total serum protein related to plasma donation, identify the influencing factors, and come up with suggestions to make plasma donation safer.

Methods

Donors from 10 plasmapheresis centers in five provinces of China participated in this study. Serum samples were collected before donation. Serum calcium was measured by arsenazo III colorimetry, and the biuret method was used for total serum protein assay. An automatic biochemical analyzer was used to conduct serum calcium and total serum protein tests.

Results

The mean serum calcium was 2.3 ± 0.15 mmol/L and total serum protein was 67.75 ± 6.02 g/L. The proportions of plasma donors whose serum calcium and total serum protein were lower than normal were 20.55% (815/3,966) and 27.99% (1,111/3,969), respectively. There were significant differences in mean serum calcium and total serum protein of plasma donors with different plasma donation frequencies, gender, age, regions, and body mass index (BMI), (all p < 0.05). Logistic regression analysis revealed that donation frequencies, age, BMI and regions were significantly associated with a higher risk of low serum calcium level, and donation frequencies, gender, age and regions were significant determinants factors of odds of abnormal total serum protein.

Conclusions

Donation frequencies, gender, age, regions, and BMI showed different effects on serum calcium and total serum protein. More attention should be paid to the age, donation frequency and region of plasma donors to reduce the probability of low serum calcium and low total serum protein.

Citric Acid: A Multifunctional Pharmaceutical Excipient

Citric acid, a tricarboxylic acid, has found wide application in the chemical and pharmaceutical industry due to its biocompatibility, versatility, and green, environmentally friendly chemistry. This review emphasizes the pharmaceutical uses of citric acid as a strategic ingredient in drug formulation while focusing on the impact of its physicochemical properties. The functionality of citric acid is due to its three carboxylic groups and one hydroxyl group. These allow it to be used in many ways, including its ability to be used as a crosslinker to form biodegradable polymers and as a co-former in co-amorphous and co-crystal applications. This paper also analyzes the effect of citric acid in physiological processes and how this effect can be used to enhance the attributes of pharmaceutical preparations, as well as providing a critical discussion on the issues that may arise out of the presence of citric acid in formulations.

Regional citrate versus heparin anticoagulation for CRRT in critically ill patients: a meta-analysis of RCTS

INTRODUCTION

This study aimed to compare the efficacy and safety of citrate and heparin in continuous renal replacement therapy (CRRT) for critically ill patients.

METHODS

Searched in PubMed, Embase, and Cochrane Library databases.

RESULTS

Analyses showed that there no difference existed in mortality, metabolic alkalosis, circuit loss, and the number of transfused between the two group(RR=0.95, P=0.40; RR=1.73, P=0.40; RR=0.64, P=0.09; RR=1.05, P=0.70). The filter life of the citrate group was longer than heparin group(MD=16.98, P<0.0001). The risk of bleeding and HIT was significantly lower in the citrate(RR=0.32, P<0.00001; RR=0.55, P=0.04). The citrate group was more susceptible to hypocalcemia(RR=4.85, P=0.0004).

CONCLUSION

Citrate anticoagulant therapy should have priority for CRRT in most critically ill patients. This article is protected by copyright. All rights reserved.

Collection, cryopreservation and thawing of stem cells for children weighing less than 25 Kg with high-risk neuroblastoma: A single center results in Morocco

Introduction

An important component of the advances made in neuroblastoma treatment has been the use of peripheral blood stem cells to support high-dose chemotherapy. In this study, we report our experience on a series of small children who have undergone standard and large volume leukaphersis (LVL) procedures, provide an update on a single institution's experience with cryopreservation of autologous peripheral blood stem cells (PBSCs), using 10% dimethyl sulfoxide (DMSO) and applying post-thaw DMSO depletion and analyze a number of variables that may affect viability.

Methods

A total of 36 aphereses were performed on 29 children weighing less than 25 kg between July 2016 and October 2019 at the Ibn Sina university hospital.

Results

Seven females and twenty-two males, median bodyweight 14 kg (9 - 22). A single apheresis was sufficient to obtain at least 3 × 10⁶/kg body weight (BW) of CD34+ cells in 82.8% of the cases. The LVL was performed in 22 aphereses. A median number of 5.9 × 10⁶/kg CD34 cells were collected per apheresis. A total of 60 PBSC samples were cryopreserved and 46 samples were infused. The mean cell viability percentage decreased from 94.75 ± 1.14% before freezing to 70.84 ± 8.6% after thawing (p < 0.001). No correlation was found between post-thaw viability and storage time (r = -0.233; p = 0.234) or number of total nucleated cells (r = 0.344; p = 0.073).

Conclusion

Leukapheresis is safe and feasible in small pediatric patients if the appropriate measures are used. Cryopreservation poses numerous challenges, especially a decrease in cell viability after thawing.

Regional Hypertonic Citrate Anticoagulation in Membrane Therapeutic Plasma Exchange: A Case Series

Rationale:

Protocols for regional citrate anticoagulation with the hypertonic 4% trisodium citrate solution have been recently described as an anticoagulation strategy during membrane therapeutic plasma exchange (mTPE). The effect of citrate in the patient’s systemic hemostasis is negligible, thus regional citrate anticoagulation application is advantageous in circumstances in which heparin-based protocols are deemed unsafe for patients with a high risk of bleeding. The downsides of using hypertonic citrate solutions are mainly hypocalcemia and hypernatremia that ultimately can cause adverse clinical events.

Presenting concerns of the patient:

(1) A 57-year-old Caucasian female with a history of active vaginal bleeding secondary to endometrial hyperplasia. She had a history of antiphospholipid syndrome, and systemic lupus erythematosus with marked refractory autoimmune thrombocytopenia. Her platelet count was persistently below 4,000/mm³ even after different immunosuppressive regimens and daily platelet transfusions. (1) A 70-year-old Caucasian female was hospitalized presenting acute kidney injury stage 3 due to rapidly progressive antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, however without the need for renal replacement therapy. At admission, serum creatinine (sCr) was 3.56 mg/dL (normal range: 0.53-1.00 mg/dL). Her baseline sCr was 0.8 mg/dL obtained 6 months earlier. Chest tomography revealed bilateral masses compatible with granulomatous lesions and no signs of alveolar bleeding. Since severe cases of ANCA vasculitis involving the lungs may evolve with alveolar hemorrhage, heparin was avoided.

Diagnoses:

(1) Systemic lupus erythematosus-associated autoimmune thrombocytopenia and (2) ANCA-associated vasculitis with kidney and lung involvement.

Interventions:

Herein, we describe a case series of 12 consecutive mTPE treatments in 2 different patients using regional 4% trisodium citrate anticoagulation.

Outcomes:

All the sessions were uneventful, presented only minor electrolyte imbalances, and were effectively completed without early interruptions due to clotting of the plasmafilter.

Teaching points:

In our 2 cases, extracorporeal regional citrate anticoagulation was successful in optimizing plasmafilter patency without bleeding events in 2 high-risk patients using established protocols for the citrate and calcium infusions.

Alteration in biochemical parameters during plateletpheresis in healthy donors: A compendious analysis

OBJECTIVES

During plateletpheresis, citrate induces hypocalcemia and hypomagnesemia, which are usually transient and self-limiting, but they can lead to significant donor discomfort. The aim of study was to determine the effect of citrate infusion on a multitude of biochemical parameters during plateletpheresis in healthy donors and to correlate changes with adverse donor reactions.

METHODS

The study was conducted on 60 healthy plateletpheresis donors. Blood samples were drawn on three occasions, a baseline pre-donation sample, 30min at start of procedure and 30min post procedure. Heparinized samples were taken to measure ionized calcium and plain samples to measure serum calcium, serum magnesium, parathyroid hormone, total protein and serum albumin.

RESULTS

There was statistically significant decline in mean total calcium (9.27±0.66mg/dl to 8.72±0.87mg/dl) and ionized calcium (3.8±0.51mg/dl to 2.9±0.67mg/dl) from baseline until 30min after the start of procedure respectively. A significant fall in serum magnesium, total protein and serum albumin was observed. The mean parathyroid hormone showed significant increase from baseline levels till at the completion of procedure (19.94±12.1pg/ml to 92.08±36.78pg/ml). If the yield was set constant, there was negative correlation between ACD used and pre-donation platelet count. Majority of adverse donor reactions were hypocalcemic reactions, which were more with Amicus double yield plateletpheresis and were managed with calcium supplementation.

CONCLUSION

Plateletpheresis induces marked reduction in serum calcium and magnesium levels. Moreover, increase in parathyroid hormone levels was significant. In addition, decline in total protein and serum albumin may be a concern in donors also participating in plasmapheresis.

Development of a Multivariable Prediction Model for Citrate Accumulation in Liver Transplant Patients Undergoing Continuous Renal Replacement Therapy with Regional Citrate Anticoagulation

INTRODUCTION

Patients with impaired citrate metabolism may experience citrate accumulation (CA), which causes life-threatening metabolic acidosis and hypocalcemia. CA poses a challenge for clinicians when deciding on the use of regional citrate anticoagulation (RCA) for patients with liver dysfunction. This study aimed to develop a prediction model integrating multiple clinical variables to assess the risk of CA in liver transplant patients.

METHODS

This single-center prospective cohort study included postoperative liver transplant patients who underwent continuous renal replacement therapy (CRRT) with RCA. The study end point was CA. A prediction model was developed using a generalized linear mixed-effect model based on the Akaike information criterion. The predictive values were assessed using the receiver operating characteristic curve and bootstrap resampling (times = 500) to estimate the area under the curve (AUC) and the corresponding 95% confidence interval (CI). A nomogram was used to visualize the model.

RESULTS

This study included 32 patients who underwent 133 CRRT sessions with RCA. CA occurred in 46 CRRT sessions. The model included lactate, norepinephrine >0.1 μg/kg/min, alanine aminotransferase, total bilirubin, and standard bicarbonate, which were tested before starting each CRRT session and body mass index, diabetes mellitus, and chronic kidney disease as predictors. The AUC of the model was 0.867 (95% CI 0.786-0.921), which was significantly higher than that of the single predictor (p < 0.05). A nomogram visualized the prediction model.

CONCLUSIONS

The prediction model integrating multiple clinical variables showed a good predictive value for CA. A nomogram visualized the model for easy application in clinical practice.

Continuous renal replacement therapy and extended indications

Extracorporeal blood purification (EBP) techniques provide support for critically ill patients with single or multiple organ dysfunction. Continuous renal replacement therapy (CRRT) is the modality of choice for kidney support for those patients and orchestrates the interactions between the different artificial organ support systems. Intensive care teams should be familiar with the concept of sequential extracorporeal therapy and plan on how to incorporate new treatment modalities into their daily practices. Importantly, scientific evidence should guide the decision-making process at the bedside and provide robust arguments to justify the costs of implementing new EBP treatments. In this narrative review, we explore the extended indications for CRRT as an adjunctive treatment to provide support for the heart, lung, liver, and immune system. We detail practicalities on how to run the treatments and how to tackle the most frequent complications regarding each of the therapies, whether applied alone or integrated. The physicochemical processes and technologies involved at the molecular level encompassing the interactions between the molecules, membranes, and resins are spotlighted. A clinical case will illustrate the timing for the initiation, maintenance, and discontinuation of EBP techniques.

Cryopreservation of platelets treated with riboflavin and UV light and stored at -80°C for 1 year

BACKGROUND

The combination of pathogen reduction technologies (PRTs) and cryopreservation can contribute to building a safe and durable platelet (PLT) inventory. Information about cryopreserved riboflavin and UV light-treated PLTs is scarce.

STUDY DESIGN AND METHODS

Twenty-four buffy coat (BC) PLT concentrates were grouped into 12 type-matched pairs, pooled, and divided into 12 non-PRT-treated control units and 12 riboflavin and UV light PRT-treated test units. Both were cryopreserved with 5% DMSO and stored at -80°C for 1 year. The cryopreservation method used was designed to avoid the formation of aggregates. PLT variables (PLT recovery, swirling, pH, MPV, and LDH) and hemostatic function measured by thromboelastography (TEG) were analyzed before cryopreservation (day 1) and post-cryopreservation at day 14 and months 3, 6, and 12 of storage at -80°C. The analyses were carried out within 1-h post-thaw.

RESULTS

No aggregates were found in either PLT group at any time. Swirling was observed in both groups. MPV increased and mean pH values decreased over time (p < .001), but the mean pH value was never below 6.4 in either group after 12 months of storage at -80°C. PLT recovery was good and clotting time became significantly shorter over the storage period in both groups (p < .001).

CONCLUSION

Our cryopreservation and thawing method prevented aggregate formation in cryopreserved riboflavin-UV-light-treated PLTs, which exhibited good recovery, swirling, pH > 6.4, and procoagulant potential, as evidenced by a reduced clotting time after 12 months of storage at -80°C. The clinical relevance of these findings should be further investigated in clinical trials.

Impact of anion exchange adsorbents on regional citrate anticoagulation

INTRODUCTION

Heparin and citrate are commonly used anticoagulants in membrane/adsorption based extracorporeal liver support systems. However, anion exchange resins employed for the removal of negatively charged target molecules including bilirubin may also deplete these anticoagulants due to their negative charge. The aim of this study was to evaluate the adsorption of citrate by anion exchange resins and the impact on extracorporeal Ca²⁺ concentrations.

METHODS

Liver support treatments were simulated in vitro. Citrate and Ca²⁺ concentrations were measured pre and post albumin filter as well as pre and post adsorbents. In addition, batch experiments were performed to quantify citrate adsorption.

RESULTS

Pre albumin filter target Ca²⁺ concentrations were reached well with only minor deviations. Citrate was adsorbed by anion exchange resins, resulting in a higher Ca²⁺ concentration downstream of the adsorbent cartridges during the first hour of treatment.

CONCLUSIONS

The anion exchange resin depletes citrate, leading to an increased Ca²⁺ concentration in the extracorporeal circuit, which may cause an increased risk of clotting during the first hour of treatment. An increase of citrate infusion during the first hour of treatment should therefore be considered to compensate for the adsorption of citrate.

Application of regional citrate anticoagulation in membrane therapeutic plasma exchange

BACKGROUND

Both regional citrate anticoagulation (RCA) and heparin are used as anticoagulants during membrane therapeutic plasma exchange (mTPE). However, there are few reports of comparisons of the two methods. The aim of this study was to compare different anticoagulants in mTPE and observe the effectiveness, safety, and advantages of RCA.

METHODS

We retrospectively included 85 patients who underwent mTPE in the past 1 year, and divided them into three groups. Patients with no bleeding tendency were administered heparin anticoagulation; patients with bleeding tendency/with liver dysfunction/who had undergone an operation were treated with RCA, or did not receive anticoagulation. In the heparin group, low-dose heparin anticoagulation was administered; in the RCA group, 4% sodium citrate solution was administered, and 10% calcium gluconate solution was pumped from the venous circuit tube. The peripheral blood platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT), and electrolytes were detected before and after treatment in all patients.

RESULTS

A total of 255 sessions of mTPE were performed in 85 patients (2-7 times/case) with 120 sessions of heparin anticoagulation, 93 sessions of RCA, and 42 sessions of no anticoagulation. Compared with pretreatment values, the platelet count decreased by 53.7% and the PT and APTT increased (p < 0.05) in the heparin group after treatment. There were no differences in platelet count and PT before and after treatment in the RCA group. In the RCA group, the patients did not experience hypocalcemia or hypercalcemia, and no separator clotting occurred.

CONCLUSION

RCA is safe, feasible, and effective in mTPE, especially for patients with bleeding tendency and frequent monitoring is needed. It is worth widely developing and applying it in clinical practice.

Regional citrate anticoagulation versus no-anticoagulation for continuous venovenous hemofiltration in patients with liver failure and increased bleeding risk: A retrospective case-control study

Objective

There are controversial opinions on anticoagulation for continuous venovenous hemofiltration (CVVH) in patients with liver failure (LF) and increased bleeding risk. Therefore, we conducted a retrospective study to evaluate the efficacy and safety of regional citrate anticoagulation (RCA) versus no-anticoagulation for CVVH in these patients.

Methods

The included patients were divided into RCA and no-anticoagulation group according to the CVVH anticoagulation strategy they accepted for CVVH. Filter lifespan, bleeding, citrate accumulation, catheter occlusion, and totCa/ionCa ratio were evaluated as outcomes.

Results

In the original cohort, the filter lifespan of the RCA group (41 patients, 79 filters) was significantly longer than the no-anticoagulation group (62 patients, 162 filters) (> 72 hours vs 39.5 hours (IQR 31.2–47.8), P = 0.002). The adjusted results demonstrated that RCA could significantly reduce the risk of filter failure (HR = 0.459, 95%CI 0.26–0.82, P = 0.008). Four episodes of totCa/ionCa > 2.5 were observed in the RCA group and continuously accepted RCA-CVVH after the reduction of citrate dose and blood flow. No obvious citrate accumulation was observed in these patients. In the matched cohort, the filter lifespan of the RCA group was significantly longer than the no-anticoagulation group (P = 0.013) as well. No significant difference in the episodes of totCa/ionCa > 2.5 was observed between the two matched groups (P = 0.074). Both in the original cohort and the matched cohort, the bleeding, acidosis, alkalosis, and catheter occlusion incidences were not significantly different between the two groups.

Conclusions

In LF patients with increased bleeding risk who underwent CVVH, RCA could prolong the filter lifespan and be safely used with careful blood gas monitoring and citrate dose adjusting. Further prospective, randomized, control studies are warranted to obtain robust evidences.

Urine Recirculation Improves Hemodynamics and Enhances Function in Normothermic Kidney Perfusion

Supplemental Digital Content is available in the text.

The study compares urine recirculation (URC) to urine replacement (UR) with Ringer’s lactate in a porcine normothermic kidney machine perfusion (NMP) model using a preclinical prototype device.

Regional citrate anticoagulation for continuous renal replacement therapy

PURPOSE OF REVIEW

The delivery of an effective dialysis dose in continuous renal replacement therapy (CRRT) depends on adequate anticoagulation of the extracorporeal circuit. In most patients, either systemic heparin anticoagulation (SHA) or regional citrate anticoagulation (RCA) is used. This review will outline the basics and rationale of RCA and summarize data on safety and efficacy of both techniques.

RECENT FINDINGS

The basic principle of RCA is to reduce the level of ionized calcium in the extracorporeal circuit via infusion of citrate. This way, effective anticoagulation restricted to the extracorporeal circuit is achieved. SHA and RCA were compared in a variety of studies. RCA significantly prolonged filter lifetime, reduced bleeding complications and provided excellent control of uremia and acid-base status. RCA was also safe in the majority of patients with impaired liver function, whereas caution must be exerted in those with severe multiorgan failure and persistent hyperlactatemia.

SUMMARY

RCA per se is safe and effective for anticoagulation of CRRT. Compared to SHA, efficacy of anticoagulation is improved and adverse effects are reduced. RCA can be recommended as the anticoagulation mode of choice for CRRT in most ICU patients.

Renal replacement therapy: a practical update

Acute kidney injury (AKI) is defined as an abrupt decrease in kidney function, with the most severe form requiring some method of renal replacement therapy (RRT). The use of RRT is required in 5-10% of critically ill patients who develop severe AKI. Renal replacement therapy can be provided as either intermittent hemodialysis or one of the various modes of continuous renal replacement therapy (CRRT), with CRRT potentially conferring an advantage with respect to renal recovery and dialysis independence. There is no difference in mortality when comparing low (< 25 mL·kg^-1·hr^-1) vs high (> 40 mL·kg^-1·hr^-1) RRT dosing. Continuous renal replacement therapy may be run in different modes of increasing complexity depending on a given patient's clinical needs. Regional citrate anticoagulation is recommended as the therapy of choice for the majority of critically ill patients requiring CRRT.

Probable Hypocalcemia Induced Ventricular Fibrillation and Torsades de Pointes following Blood Product Administration

A 35-year-old male underwent open-heart surgery and required multiple blood product transfusions. Citrate, a preservative in blood products, caused serum ionized calcium chelation leading to hypocalcemia, a prolonged corrected QT (QTc) interval, and separate episodes of ventricular fibrillation and torsades de pointes (TdP). This case highlights an uncommon complication of blood product transfusion-induced hypocalcemia with precipitant arrhythmia.

Renal replacement therapy and anticoagulation

Today, up to 20% of all intensive care unit patients require renal replacement therapy (RRT), and continuous renal replacement therapies (CRRT) are the preferred technique. In CRRT, effective anticoagulation of the extracorporeal circuit is mandatory to prevent clotting of the circuit or filter and to maintain filter performance. At present, a variety of systemic and regional anticoagulation modes for CRRT are available. Worldwide, unfractionated heparin is the most widely used anticoagulant. All systemic techniques are associated with significant adverse effects. Most important are bleeding complications and heparin-induced thrombocytopenia (HIT-II). Regional citrate anticoagulation (RCA) is a safe and effective technique. Compared to systemic anticoagulation, RCA prolongs filter running times, reduces bleeding complications, allows effective control of acid-base status, and reduces adverse events like HIT-II. In this review, we will discuss systemic and regional anticoagulation techniques for CRRT including anticoagulation for patients with HIT-II. Today, RCA can be recommended as the therapy of choice for the majority of critically ill patients requiring CRRT.