Membrane pressures predict clotting of pediatric continuous renal replacement therapy circuits

A predictive model for real-time LSTM methods: Monitoring dynamic transmembrane pressure improves loop life and anticoagulant therapy accuracy in continuous renal replacement therapy

BackgroundContinuous Renal Replacement Therapy (CRRT), is essential for managing acute kidney injury (AKI) Dynamic monitoring of transmembrane pressure (TMP) during CRRT is crucial for predicting filter clotting and optimizing filter lifespan, which indirectly supports anticoagulation management.ObjectiveTo prolong the lifespan of CRRT circuits and enhance the precision of anticoagulation therapy by developing a predictive early warning model for CRRT circuit life, based on dynamic TMP monitoring.MethodsWe conducted a retrospective analysis in the ICU of the First Affiliated Hospital of Army Medical University. Leveraging the TMP data recorded by CRRT machines, we established an adaptive real-time predictive modeling framework, termed DTP (Dynamic Transmembrane Pressure Prediction), utilizing Long Short-Term Memory (LSTM) networks. This framework predicts TMP trends as an early indicator of filter clotting. Our models were validated using over 20,000 min of clinical data from 405 CRRT cases, predicting TMP trajectories within 50 min.ResuitsIn simulated treatment evaluations, our LSTM models accurately identified impending TMP increases, achieving recall rates exceeding 0.97 and F2 scores above 0.93. Notably, an average warning time of 23 min was provided prior to the TMP reaching the critical 260 mmHg threshold, indicating substantial filter clotting. An analysis of false alarms revealed patterns consistent with emerging instability and transient artifacts.ConclusionThe personalized early warning model developed within the DTP framework effectively predicts TMP changes, enhancing the accuracy and timeliness of medical interventions. This improvement reduces the incidence of adverse events, maximizes the lifespan of CRRT circuits, and ultimately decreases treatment and personnel costs.

Comparison of regional citrate anticoagulation and nafamostat mesylate anticoagulation during plasma exchange for children at high bleeding risk: a retrospective study

BACKGROUND

There is currently no established optimal anticoagulation protocol for plasma exchange (PE) in pediatric patients at a high risk of bleeding. Therefore, we aimed to evaluate the efficacy and safety of regional citrate anticoagulation (RCA) and nafamostat mesylate (NM) for PE anticoagulation in this patient group.

METHODS

This retrospective study analyzed data from 66 children with high bleeding risk who underwent PE in the Pediatric Intensive Care Unit of Hunan Children's Hospital between June 2018 and January 2023. Patients were divided into two groups: RCA-PE (n = 45) and NM-PE (n = 21), and filter performance and adverse reaction rates were compared. Statistical analysis utilized SPSS 25.0, comprising two-sample t-tests, chi-square or Fisher's exact tests, and Mann-Whitney U tests, as appropriate. Data visualization was performed using ggplot2 in R-studio. P < 0.05 was considered statistically significant.

RESULTS

No statistically significant differences were found between the two groups in initial transmembrane pressure (TMP) [17.0 (14.0, 21.5) mmHg vs. 16.0 (14.0, 19.5) mmHg, P = 0.614], maximum TMP [46.0 (42.0, 49.5) mmHg vs. 43.0 (41.5, 49.5) mmHg, P = 0.689], and final TMP [40.0 (35.5, 45.0) mmHg vs. 38.0 (35.0, 42.0) mmHg, P = 0.298]. Filter grade distribution and bleeding events also showed no statistically significant difference between the groups. However, the NM-PE group had significantly lower overall adverse reaction and metabolic alkalosis rates (both P < 0.05) compared to the RCA-PE group.

CONCLUSIONS

NM demonstrates similar efficacy but superior safety compared with RCA, making it a more suitable anticoagulation strategy for children with high bleeding risk. Study limitations include single-center design, selection bias, and uncertain NM dosage.

Change in prefilter pressure as a key determinant in the decision to return blood in continuous renal replacement therapy: An observational study

BACKGROUND

During continuous renal replacement therapy (CRRT), circuit coagulation is an important event that can result in suboptimal outcomes. Nurses must remain alert throughout the treatment and observe machine pressures. Transmembrane pressure (TMP) is commonly used for monitoring but it is sometimes too late to return blood to the patient.

AIM

To compare the capacity of prefilter pressure (FP) versus TMP to predict the risk of circuit coagulation in adult patients with acute renal failure on CRRT.

STUDY DESIGN

An observational, longitudinal, prospective study. This study was carried out in a tertiary referral hospital over 2 years. Data collected included the following variables: TMP, filter or FP, effluent pressure, venous and arterial pressure, filtration fraction, and ultrafiltration constant of each circuit. Means and their trends over time were collected, for both diffusive and convective therapy and for two membrane types.

RESULTS

A total of 151 circuits (24 polysulfone and 127 acrylonitrile) were analysed, from 71 patients (n = 22 [34%] women; mean age, 66.5 [36-84] years). Of the total treatments, 80 were diffusive, and the rest were convective or mixed. In the diffusive circuits, a progressive rise in FP was observed without an increase in TMP and with an increasing trend in effluent pressure. Circuit lifespan was between 2 and 90 h. In 11% (n = 17) of the cases, the blood could not be returned to the patient.

CONCLUSION

These findings allowed the creation of graphs that indicate the appropriate point to return blood to the patient. FP was a major determinant in this decision; in most cases, TMP was not a reliable parameter. Our findings are applicable to convective, diffusive, and mixed treatments as well as both types of membranes used in this acute setting.

RELEVANCE TO CLINICAL PRACTICE

This study provides two clear reference graphs showing risk scales for the assessment of circuit pressures in CRRT. The graphs proposed here can be used to evaluate any machine on the market and the two types of membranes used in this acute setting. Both convective and diffusive circuits can be assessed, allowing safer evaluation in patients who change treatment.

Development and external validation of a prediction model for the premature circuit clotting of continuous renal replacement therapy in critically ill patients

OBJECTIVE

This study aimed to develop and validate a prediction model for premature circuit clotting of continuous renal replacement therapy (CRRT) in critically ill patients.

DESIGN

A retrospective cohort study was conducted on ICU patients undergoing CRRT. The Medical Information Mart for Intensive Care-III Clinical Database CareVue subset and Medical Information Mart for Intensive Care-IV were utilized for model development, while the eICU Collaborative Research Database was employed for external validation. Predictive factors were selected through Least Absolute Shrinkage and Selection Operator Regression and univariate logistic regression. A prediction model was then developed using binary logistic regression. Internal and external validations assessed the model's discrimination, calibration, and clinical net benefit.

RESULTS

This study encompassed 2531 patients overall, with a premature circuit clotting rate of 31.88 %. The prediction model comprises five variables: body temperature, anticoagulation, mean arterial pressure, maximum transmembrane pressure change within two hours, and vasopressor. The model demonstrated robust predictive performance, achieving an area under the receiver operating characteristic curve of 0.897 (95 % CI: 0.879-0.915) in the training set and 0.877 (95 % CI: 0.852-0.902) in the external validation set. Internal validation yielded a Brier score of 0.087, while external validation showed a Brier score of 0.120. Calibration curves indicated good model calibration for both validations. The decision curve analysis indicates that the model yields a clinical net benefit across a wide range of decision thresholds.

CONCLUSION

The model demonstrates robust discrimination, calibration, and clinical net benefit, with readily available variables indicating substantial potential for valuable clinical applications.

IMPLICATIONS FOR CLINICAL PRACTICE

Healthcare providers in the ICU can leverage the model to evaluate the risk of premature circuit clotting in critically ill patients undergoing continuous renal replacement therapy, facilitating timely intervention to mitigate its incidence.

How to safeguard the continuous renal replacement therapy circuit: a narrative review

The high prevalence of acute kidney injury (AKI) in ICU patients emphasizes the need to understand factors influencing continuous renal replacement therapy (CRRT) circuit lifespan for optimal outcomes. This review examines key pharmacological interventions-citrate (especially in regional citrate anticoagulation), unfractionated heparin (UFH), low molecular weight heparin (LMWH), and nafamostat mesylate (NM)-and their effects on filter longevity. Citrate shows efficacy with lower bleeding risks, while UFH remains cost-effective, particularly in COVID-19 cases. LMWH is effective but associated with higher bleeding risks. NM is promising for high-bleeding risk scenarios. The review advocates for non-tunneled, non-cuffed temporary catheters, especially bedside-inserted ones, and discusses the advantages of surface-modified dual-lumen catheters. Material composition, such as polysulfone membranes, impacts filter lifespan. The choice of treatment modality, such as Continuous Veno-Venous Hemodialysis (CVVHD) or Continuous Veno-Venous Hemofiltration with Dialysis (CVVHDF), along with the management of effluent volume, blood flow rates, and downtime, are critical in prolonging filter longevity in CRRT. Patient-specific conditions, particularly the type of underlying disease, and the implementation of early mobilization strategies during CRRT are identified as influential factors that can extend the lifespan of CRRT filters. In conclusion, this review offers insights into factors influencing CRRT circuit longevity, supporting evidence-based practices and suggesting further multicenter studies to guide ICU clinical decisions.

Impact of Continuous Renal Replacement Therapy Initiation Time, Kidney Injury, and Hypervolemia in Critically Ill Children

BACKGROUND

The mortality rate of pediatric patients who require continuous renal replacement therapy is approximately 42%, and outcomes vary considerably depending on underlying disease, illness severity, and time of dialysis initiation. Delay in the initiation of such therapy may increase mortality risk, prolong intensive care unit stay, and worsen clinical outcomes.

LOCAL PROBLEM

In the pediatric intensive care unit of an urban level I trauma children's hospital, continuous renal replacement therapy initiation times and factors associated with delays in therapy were unknown.

METHODS

This quality improvement process involved a retrospective review of data on patients who received continuous dialysis in the pediatric intensive care unit from January 1, 2017, to December 31, 2021. The objectives were to examine the characteristics of the children requiring continuous renal replacement therapy, therapy initiation times, and factors associated with initiation delays that might affect unit length of stay and mortality.

RESULTS

During the study period, 175 patients received continuous renal replacement therapy, with an average initiation time of 11.9 hours. Statistically significant associations were found between the degree of fluid overload and mortality (P < .001) and between the presence of acute kidney injury and prolonged length of stay (P = .04). No significant association was found between therapy initiation time and unit length of stay or mortality, although the average initiation time of survivors was 5.9 hours shorter than that of nonsurvivors.

CONCLUSION

Future studies are needed to assess real time delays and to evaluate if the implementation of a standardized initiation process decreases initiation time.

Solute Clearance Evaluation and Filter Clotting Prediction in Continuous Renal Replacement Therapy

Unexpected filter clotting is a major problem in continuous renal replacement therapy (CRRT). Reduced solute clearance is observed prior to filter clotting. This single-center, retrospective, observational study aimed to determine whether reduced solute clearance of low- and medium-molecular-weight molecules in CRRT can predict filter clotting. Solute clearances of urea and myoglobin (Mb) were measured at 24 h after initiation of continuous hemodiafiltration (CHDF). Clearance per flow (CL/F) was calculated. The primary outcome was clotting of the filter in the subsequent 24 h, and 775 CHDF treatments conducted on 230 patients for at least 24 consecutive hours in our ICU were analyzed. Filter clotting was observed in 127 treatments involving 39 patients. Urea and Mb CL/F at 24 h were significantly lower in the patients who experienced clotting. Further analysis was limited to the first CHDF treatment of each patient to adjust for confounding factors. Multivariate logistic regression analysis revealed that both urea CL/F < 94% and Mb CL/F < 64% were significant predictors of clotting within the next 24 h. Lower urea and Mb CL/F measured at 24 h after CRRT initiation were associated with filter clotting in the next 24 h. Further study is necessary to ascertain whether measurement of urea and MB CL/F will help with avoiding unexpected filter clotting.

Anticoagulation in patients with acute kidney injury undergoing kidney replacement therapy

Kidney replacement therapy (KRT) is used to provide supportive therapy for critically ill patients with severe acute kidney injury and various other non-renal indications. Modalities of KRT include continuous KRT (CKRT), intermittent hemodialysis (HD), and sustained low efficiency daily dialysis (SLED). However, circuit clotting is a major complication that has been investigated extensively. Extracorporeal circuit clotting can cause reduction in solute clearances and can cause blood loss, leading to an upsurge in treatment costs and a rise in workload intensity. In this educational review, we discuss the pathophysiology of the clotting cascade within an extracorporeal circuit and the use of various types of anticoagulant methods in various pediatric KRT modalities.

Regional Citrate Anticoagulation and Systemic Anticoagulation during Pediatric Continuous Renal Replacement Therapy: A Systematic Literature Review

Background: Clotting is a major drawback of continuous renal replacement therapy (CRRT) performed on critically ill pediatric patients. Although anticoagulation is recommended to prevent clotting, limited results are available on the effect of each pharmacological strategy in reducing filter clotting in pediatric CRRT. This study defines which anticoagulation strategy, between regional citrate anticoagulation (RCA) and systemic anticoagulation with heparin, is safer and more efficient in reducing clotting, patient mortality, and treatment complications during pediatric CRRT. Methods: A systematic literature review was run considering papers published in English until December 2021 and describing patients’ and treatments’ complications in CRRT performed with heparin and RCA on patients aged less than 18 years. Results: Eleven studies were considered, cumulatively comprising 1.706 CRRT sessions (62% with systemic anticoagulation and 38% with RCA). Studies have consistently identified RCA’s superiority over systemic anticoagulation with heparin in prolonging circuit life. The pooled estimate (95% CI) of filter clotting risk showed that RCA is a protective factor for clotting risk (RR = 0.204). Conclusions: RCA has a potential role in prolonging circuit life and seems superior to systemic anticoagulation with heparin in decreasing the risk of circuit clotting during CRRT performed in critically ill pediatric patients.

A Meta-Analysis of Extracorporeal Anticoagulants in Pediatric Continuous Kidney Replacement Therapy

OBJECTIVE

Continuous kidney replacement therapy (CKRT) is the primary therapeutic modality utilized in hemodynamically unstable patients with severe acute kidney injury. As the circuit is extracorporeal, it poses an increased risk of blood clotting and circuit loss; frequent circuit losses affect the provider's ability to provide optimal treatment. The objective of this meta-analysis is to evaluate the safety and efficacy of the extracorporeal anticoagulants in the pediatric CKRT population.

DATA SOURCES

We conducted a literature search on PubMed/Medline and Embase for relevant citations.

STUDY SELECTION

Studies were included if they involved patients under the age of 18 years undergoing CKRT, with the use of anticoagulation (heparin, citrate, or prostacyclin) as a part of therapy. Only English articles were included in the study.

DATA EXTRACTION

Initial search yielded 58 articles and a total of 24 articles were included and reviewed. A meta-analysis was performed focusing on the safety and effectiveness of regional citrate anticoagulation (RCA) vs unfractionated heparin (UFH) anticoagulants in children.

DATA SYNTHESIS

RCA had statistically significantly longer circuit life of 50.65 hours vs. UFH of 42.10 hours. Two major adverse effects metabolic alkalosis and electrolyte imbalance seen more commonly in RCA compared to UFH. There was not a significant difference in the risk of systemic bleeding when comparing RCA vs. UFH.

CONCLUSION

RCA is the preferred anticoagulant over UFH due to its significantly longer circuit life, although vigilant circuit monitoring is required due to the increased risk of electrolyte disturbances. Prostacyclin was not included in the meta-analysis due to the lack of data in pediatric patients. Additional studies are needed to strengthen the study results further.

Disruptive technologies for hemodialysis: medium and high cutoff membranes. Is the future now?

In the past decade, a new class of hemodialysis (HD) membranes (high retention onset class) became available for clinical use. The high cutoff (HCO) and the medium cutoff (MCO) membranes have wider pores and more uniformity in pore size, allowing an increased clearance of uremic toxins. Owing to the mechanism of backfiltration/internal filtration, middle molecules are dragged by the convective forces, and no substitution solution is needed. The HCO dialyzer is applied in septic patients with acute kidney injury requiring continuous kidney replacement therapy. The immune response is modulated thanks to the removal of inflammatory mediators. Another current application for the HCO dialyzer is in hematology, for patients on HD secondary to myeloma-kidney, since free light chains are more efficiently removed with the HCO membrane, reducing their deleterious effect on the renal tubules. In its turn, the MCO dialyzer is used for maintenance HD patients. A myriad of clinical trials published in the last three years consistently demonstrates the ability of this membrane to remove uremic toxins more efficiently than the high-flux membrane, an evolutionary disruption in the HD standard of care. Safety concerns regarding albumin loss as well as blood contamination from pyrogens in the dialysate have been overcome. In this update article, we explore the rise of new dialysis membranes in the light of the scientific evidence that supports their use 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.

The Effect of Patient- and Treatment-Related Factors on Circuit Lifespan During Continuous Renal Replacement Therapy in Critically Ill Children

OBJECTIVES

To examine the effects of patient and treatment variables on circuit lifespan in critically ill children requiring continuous renal replacement therapy.

DESIGN

Retrospective observational study based on a prospective registry.

SETTING

Tertiary referral 30-bed PICU.

PATIENTS

One hundred sixty-one critically ill children undergoing continuous renal replacement therapy during an 8-year period (2007-2014) were included in the study.

INTERVENTIONS

Continuous renal replacement therapy.

MEASUREMENTS AND MAIN RESULTS

During the study period, 161 patients received a total of 22,190 hours of continuous renal replacement therapy, with a median duration of 74.75 hours (interquartile range, 32-169.5) per patient. Of the 572 filter circuits used, 276 (48.3%) were changed due to circuit clotting and 262 (45.8%) were electively changed. Median circuit life was 24.62 hours (interquartile range, 10.6-55.3) for all filters and significantly longer for those electively removed as compared to those prematurely removed because of clotting (35.50 hr [interquartile range, 16.9-67.6] vs 22.00 hr [interquartile range, 13.8-42.5]; p < 0.001). Multivariate regression analyses revealed that admission diagnosis (p < 0.001), anticoagulation type (p < 0.001), access type (p = 0.016), and circuit size (p = 0.027) were associated with prolonged circuit life, as well as, in patients on heparin anticoagulation, with higher doses of heparin (p < 0.001) and a prolonged activated partial thromboplastin time (p < 0.001).

CONCLUSIONS

In this study, circuit lifespan in pediatric continuous renal replacement therapy was low and appeared to depend upon the patient's diagnosis, the type of access and anticoagulation used as well as the size of the circuit used.