A comparison of the Niagara and Medcomp catheters for continuous renal replacement therapy

The Association Between Catheter Type and Dialysis Treatment: A Retrospective Data Analysis at Two U.S.-Based ICUs

Dialysis catheter type may be associated with differences in continuous renal replacement therapy (CRRT) treatment in the critically ill, with potential implications for patient outcomes and healthcare costs.

OBJECTIVES

To evaluate the association between the catheter type and multiple dialysis treatment outcomes among the critically ill.

DESIGN

Retrospective, observational study.

SETTING

Two U.S.-based ICUs.

PARTICIPANTS

Critically ill patients receiving CRRT between April 1, 2018, and July 1, 2020. A total of 1,037 CRRT sessions were analyzed.

MAIN OUTCOMES AND MEASURES

Circuit life, alarm interruption frequency (including a subset of vascular access [VA]-related alarms), termination type (elective vs nonelective), and blood flow rates. Pre- (n = 530) and post-catheter change (n = 507) periods were assessed, and the post-change period was further divided into intervals of pre-COVID (n = 167) and COVID contemporaneous (n = 340) to account for the pandemic's impact.

RESULTS

Compared with pre-change sessions, post-change sessions had 31% longer circuit life (95% CI, 1.14-1.49; p < 0.001), 3% higher blood flow rate (1.01-1.05; p < 0.01), and lower proportion of nonelective terminations (adjusted odds ratio [OR], 0.42 [0.28-0.62]; p < 0.001). There were fewer interruptions for all alarms (adjusted count ratio, 0.95 [0.87-1.05]; p = 0.31) and VA-related alarms (0.80 [0.66-0.96]; p = 0.014). The sessions during COVID period were statistically similar to pre-COVID sessions for all outcomes except a lower proportion of nonelective terminations (adjusted OR, 0.39 [0.22-0.70]; p < 0.01).

CONCLUSIONS

A change in catheter type was associated with longer CRRT sessions with fewer interruptions and unexpected terminations in a population of critical patients.

Vascular access, membranes and circuit for CRRT

The advances in the technology for providing continuous renal replacement therapy (CRRT) have led to an increase in its utilization throughout the world. However, circuit life continues to be a major problem. It leads not only to decreased delivery of dialysis but also causes blood loss, waste of disposables, alters dose delivery of medications and nutrition, and increases nurse workload, all of which increases healthcare cost. Premature circuit failure can be caused by numerous factors that can be difficult to dissect out. The first component is the vascular access; without a well-placed, functioning access, delivery of CRRT becomes very difficult. This is usually accomplished by placing a short-term dialysis catheter into either the right internal jugular or femoral vein. The tips should be located at the caval atrial junction or inferior vena cava. In addition to establishing suitable vascular access, a comprehensive understanding of the circuit facilitates the development of a methodical approach in providing efficient CRRT characterized by optimal circuit life. Moreover, it aids in determining the cause of circuit failure in patients experiencing recurrent episodes. This review therefore summarizes the essential points that guide providers in establishing optimal vascular access. We then provide an overview of the main components of the CRRT circuit including the blood and fluid pumps, the hemofilter, and pressure sensors, which will assist in identifying the key mechanisms contributing to premature failure of the CRRT circuit.

Clinical Survey of Decreased Blood Flow Rate in Continuous Renal Replacement Therapy: A Retrospective Observational Study

Background

Continuous renal replacement therapy (CRRT) is an essential procedure for patients with acute kidney injury in intensive care. It is important to maintain an adequate blood flow rate during CRRT. Several previous studies have reported the relationships between blood flow rate and filter lifespan, or circuit life, in CRRT. Here, we aim at elucidating the incidence and factors associated with a decreased blood flow rate in CRRT.

Methods

This is a retrospective observational study. From January 2014 to June 2017, 119 patients who underwent CRRT in the intensive care unit were enrolled. The definition of a decreased blood flow rate included situations in which the medical staff needed to decrease the blood flow volume. We statistically analyzed the association of the decreased blood flow rate with patients' clinical characteristics.

Results

Of 119 patients, 52 required a decreased blood flow rate during CRRT. Almost half of the cases occurred within one day of starting CRRT. None of the clinical factors (age, sex, height, sequential organ failure assessment (SOFA) score, catheter position, systemic infection, albumin, hemoglobin, and activating coagulation time) were significantly associated with decreased blood flow rate.

Conclusions

A decreased blood flow rate often occurs during CRRT. Clinical factors significantly associated with the occurrence of the decreased blood flow rate were not detected in the current study. Further investigation regarding the occurrence of a decreased blood flow is warranted.

Non anti-coagulant factors associated with filter life in continuous renal replacement therapy (CRRT): a systematic review and meta-analysis

BACKGROUND

Optimising filter life and performance efficiency in continuous renal replacement therapy has been a focus of considerable recent research. Larger high quality studies have predominantly focussed on optimal anticoagulation however CRRT is complex and filter life is also affected by vascular access, circuit and management factors. We performed a systematic search of the literature to identify and quantify the effect of vascular access, circuit and patient factors that affect filter life and presented the results as a meta-analysis.

METHODS

A systematic review and meta-analysis was performed by searching Pubmed (MEDLINE) and Ovid EMBASE libraries from inception to 29th February 2016 for all studies with a comparator or independent variable relating to CRRT circuits and reporting filter life. Included studies documented filter life in hours with a comparator other than anti-coagulation intervention. All studies comparing anticoagulation interventions were searched for regression or hazard models pertaining to other sources of variation in filter life.

RESULTS

Eight hundred nineteen abstracts were identified of which 364 were selected for full text analysis. 24 presented data on patient modifiers of circuit life, 14 on vascular access modifiers and 34 on circuit related factors. Risk of bias was high and findings are hypothesis generating. Ranking of vascular access site by filter longevity favours: tunnelled semi-permanent catheters, femoral, internal jugular and subclavian last. There is inconsistency in the difference reported between femoral and jugular catheters. Amongst published literature, modality of CRRT consistently favoured continuous veno-venous haemodiafiltration (CVVHD-F) with an associated 44% lower failure rate compared to CVVH. There was a trend favouring higher blood flow rates. There is insufficient data to determine advantages of haemofilter membranes. Patient factors associated with a statistically significant worsening of filter life included mechanical ventilation, elevated SOFA or LOD score, elevations in ionized calcium, elevated platelet count, red cell transfusion, platelet factor 4 (PF-4) antibodies, and elevated fibrinogen. Majority of studies are observational or report circuit factors in sub-analysis. Risk of bias is high and findings require targeted investigations to confirm.

CONCLUSION

The interaction of patient, pathology, anticoagulation, vascular access, circuit and staff factors contribute to CRRT filter life. There remains an ambiguity from published data as to which site and side should be the first choice for vascular access placement and what interaction this has with patient factors and timing. Early consideration of tunnelled semi-permanent access may provide optimal filter life if longer periods of CRRT are anticipated. There remains an absence of robust evidence outside of anti-coagulation strategies despite over 20 years of therapy delivery however trends favour CVVHD-F over CVVH.

Implementation of a Simplified Regional Citrate Anticoagulation Protocol for Post-Dilution Continuous Hemofiltration Using a Bicarbonate Buffered, Calcium Containing Replacement Solution

Background/Aims: Recent updates to the Nikkiso Aquarius continuous renal replacement therapy (CRRT) platform allowed us to develop a post-dilution protocol for regional citrate anticoagulation (RCA) using standard bicarbonate buffered, calcium containing replacement solution with acid citrate dextrose formula-A as a citrate source. Our objective was to demonstrate that the protocol was safe and effective. Methods: Prospective audit of consecutive patients receiving RCA for CRRT within intensive care unit, who were either contraindicated to heparin or had poor filter lifespan (<12 h for 2 consecutive filters) on heparin. Results: We present the first 29 patients who used 98 filters. After excluding ‘non-clot' filter loss, 50% had a duration of >27 h. Calcium supplementation was required for 30 (30%) filter circuits, in 17 of 29 (58%) patients. One patient discontinued the treatment due to metabolic alkalosis, but there were no adverse bleeding events. Conclusion: Post-dilution RCA system is effective and simple to use on the Aquarius platform and results in comparable filter life for patients relatively contraindicated to heparin.

Early mobilization on continuous renal replacement therapy is safe and may improve filter life

Introduction

Despite studies demonstrating benefit, patients with femoral vascular catheters placed for continuous renal replacement therapy are frequently restricted from mobilization. No researchers have reported filter pressures during mobilization, and it is unknown whether mobilization is safe or affects filter lifespan. Our objective in this study was to test the safety and feasibility of mobilization in this population.

Methods

A total of 33 patients undergoing continuous renal replacement therapy via femoral, subclavian or internal jugular vascular access catheters at two general medical-surgical intensive care units in Australia were enrolled. Patients underwent one of three levels of mobilization intervention as appropriate: (1) passive bed exercises, (2) sitting on the bed edge or (3) standing and/or marching. Catheter dislodgement, haematoma and bleeding during and following interventions were evaluated. Filter pressure parameters and lifespan (hours), nursing workload and concern were also measured.

Results

No episodes of filter occlusion or failure occurred during any of the interventions. No adverse events were detected. The intervention filters lasted longer than the nonintervention filters (regression coefficient = 13.8 (robust 95% confidence interval (CI) = 5.0 to 22.6), P = 0.003). In sensitivity analyses, we found that filter life was longer in patients who had more position changes (regression coefficient = 2.0 (robust 95% CI = 0.6 to 3.5), P = 0.007). The nursing workloads between the intervention shift and the following shift were similar.

Conclusions

Mobilization during renal replacement therapy via a vascular catheter in patients who are critically ill is safe and may increase filter life. These findings have significant implications for the current mobility restrictions imposed on patients with femoral vascular catheters for renal replacement therapy.

Trial registration

Australian and New Zealand Clinical Trials Registry ACTRN12611000733976 (registered 13 July 2011)

Electronic supplementary material

The online version of this article (doi:10.1186/cc14001) contains supplementary material, which is available to authorized users.