Vascular access sites for acute renal replacement in intensive care units

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.

Risk factors of hemodialysis catheter dysfunction in patients undergoing continuous renal replacement therapy: a retrospective study

BACKGROUND

Continuous renal replacement therapy is a relatively common modality applied to critically ill patients with renal impairment. To maintain stable continuous renal replacement therapy, sufficient blood flow through the circuit is crucial, but catheter dysfunction reduces the blood flow by inadequate pressures within the circuit. Therefore, exploring and modifying the possible risk factors related to catheter dysfunction can help to provide continuous renal replacement therapy with minimal interruption.

METHODS

Adult patients who received continuous renal replacement therapy at Seoul National University Hospital between January 2019 and December 2021 were retrospectively analyzed. Patients who received continuous renal replacement therapy via a temporary hemodialysis catheter, inserted at the bedside under ultrasound guidance within 12 h of continuous renal replacement therapy initiation were included.

RESULTS

A total of 507 continuous renal replacement therapy sessions in 457 patients were analyzed. Dialysis catheter dysfunction occurred in 119 sessions (23.5%). Multivariate analysis showed that less prolonged prothrombin time (adjusted OR 0.49, 95% CI, 0.30-0.82, p = 0.007) and activated partial thromboplastin time (adjusted OR 1.01, 95% CI, 1.00-1.01, p = 0.049) were associated with increased risk of catheter dysfunction. Risk factors of re-catheterization included vascular access to the left jugular and femoral vein.

CONCLUSIONS

In critically ill patients undergoing continuous renal replacement therapy, less prolonged prothrombin time was associated with earlier catheter dysfunction. Use of left internal jugular veins and femoral vein were associated with increased risk of re-catheterization compared to the right internal jugular vein.

Non-pharmacological interventions for preventing clotting of extracorporeal circuits during continuous renal replacement therapy

BACKGROUND

Acute kidney injury (AKI) is a common complication amongst people who are critically ill, and it is associated with an increased risk of death. For people with severe AKI, continuous kidney replacement therapy (CKRT), which is delivered over 24 hours, is needed when they become haemodynamically unstable. When CKRT is interrupted due to clotting of the extracorporeal circuit, the delivered dose is decreased and thus leading to undertreatment.

OBJECTIVES

This review assessed the efficacy of non-pharmacological measures to maintain circuit patency in CKRT.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 25 January 2021 which includes records identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) (parallel-group and cross-over studies), cluster RCTs and quasi-RCTs that examined non-pharmacological interventions to prevent clotting of extracorporeal circuits during CKRT.  DATA COLLECTION AND ANALYSIS: Three pairs of review authors independently extracted information including participants, interventions/comparators, outcomes, study methods, and risk of bias. The primary outcomes were circuit lifespan and death due to any cause at day 28. We used a random-effects model to perform quantitative synthesis (meta-analysis). We assessed risk of bias in included studies using the Cochrane Collaboration's tool for assessing risk of bias. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

A total of 20 studies involving 1143 randomised participants were included in the review. The methodological quality of the included studies was low, mainly due to the unclear randomisation process and blinding of the intervention. We found evidence on the following 11 comparisons: (i) continuous venovenous haemodialysis (CVVHD) versus continuous venovenous haemofiltration (CVVH) or continuous venovenous haemodiafiltration (CVVHDF); (ii) CVVHDF versus CVVH; (iii) higher blood flow (≥ 250 mL/minute) versus standard blood flow (< 250 mL/minute); (iv) AN69 membrane (AN69ST) versus other membranes; (v) pre-dilution versus post-dilution; (vi) a longer catheter (> 20 cm) placing the tip targeting the right atrium versus a shorter catheter (≤ 20 cm) placing the tip in the superior vena cava; (vii) surface-modified double-lumen catheter versus standard double-lumen catheter with identical geometry and flow design; (viii) single-site infusion anticoagulation versus double-site infusion anticoagulation; (ix) flat plate filter versus hollow fibre filter of the same membrane type; (x) a filter with a larger membrane surface area versus a smaller one; and (xi) a filter with more and shorter hollow fibre versus a standard filter of the same membrane type. Circuit lifespan was reported in 9 comparisons. Low certainty evidence indicated that CVVHDF (versus CVVH: MD 10.15 hours, 95% CI 5.15 to 15.15; 1 study, 62 circuits), pre-dilution haemofiltration (versus post-dilution haemofiltration: MD 9.34 hours, 95% CI -2.60 to 21.29; 2 studies, 47 circuits; I² = 13%), placing the tip of a longer catheter targeting the right atrium (versus placing a shorter catheter targeting the tip in the superior vena cava: MD 6.50 hours, 95% CI 1.48 to 11.52; 1 study, 420 circuits), and surface-modified double-lumen catheter (versus standard double-lumen catheter: MD 16.00 hours, 95% CI 13.49 to 18.51; 1 study, 262 circuits) may prolong circuit lifespan. However, higher blood flow may not increase circuit lifespan (versus standard blood flow: MD 0.64, 95% CI -3.37 to 4.64; 2 studies, 499 circuits; I² = 70%). More and shorter hollow fibre filters (versus standard filters: MD -5.87 hours, 95% CI -10.18 to -1.56; 1 study, 6 circuits) may reduce circuit lifespan. Death from any cause was reported in four comparisons We are uncertain whether CVVHDF versus CVVH, CVVHD versus CVVH or CVVHDF, longer versus a shorter catheter, or surface-modified double-lumen catheters versus standard double-lumen catheters reduced death due to any cause, in very low certainty evidence. Recovery of kidney function was reported in three comparisons. We are uncertain whether CVVHDF versus CVVH, CVVHDF versus CVVH, or surface-modified double-lumen catheters versus standard double-lumen catheters increased recovery of kidney function. Vascular access complications were reported in two comparisons. Low certainty evidence indicated using a longer catheter (versus a shorter catheter: RR 0.40, 95% CI 0.22 to 0.74) may reduce vascular access complications, however the use of surface-modified double lumen catheters versus standard double-lumen catheters may make little or no difference to vascular access complications.

AUTHORS' CONCLUSIONS

The use of CVVHDF as compared with CVVH, pre-dilution haemofiltration, a longer catheter, and surface-modified double-lumen catheter may be useful in prolonging the circuit lifespan, while higher blood flow and more and shorter hollow fibre filter may reduce circuit life. The Overall, the certainty of evidence was assessed to be low to very low due to the small sample size of the included studies. Data from future rigorous and transparent research are much needed in order to fully understand the effects of non-pharmacological interventions in preventing circuit coagulation amongst people with AKI receiving CKRT.

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.

Vascular access for renal replacement therapy among 459 critically ill patients: a pragmatic analysis of the randomized AKIKI trial

BACKGROUND

Vascular access for renal replacement therapy (RRT) is routine question in the intensive care unit. Randomized trials comparing jugular and femoral sites have shown similar rate of nosocomial events and catheter dysfunction. However, recent prospective observational data on RRT catheters use are scarce. We aimed to assess the site of RRT catheter, the reasons for catheter replacement, and the complications according to site in a large population of critically ill patients with acute kidney injury.

PATIENTS AND METHODS

We performed an ancillary study of the AKIKI study, a pragmatic randomized controlled trial, in which patients with severe acute kidney injury (KDIGO 3 classification) with invasive mechanical ventilation, catecholamine infusion or both were randomly assigned to either an early or a delayed RRT initiation strategy. The present study involved all patients who underwent at least one RRT session. Number of RRT catheters, insertion sites, factors potentially associated with the choice of insertion site, duration of catheter use, reason for catheter replacement, and complications were prospectively collected.

RESULTS

Among the 619 patients included in AKIKI, 462 received RRT and 459 were finally included, with 598 RRT catheters. Femoral site was chosen preferentially (n = 319, 53%), followed by jugular (n = 256, 43%) and subclavian (n = 23, 4%). In multivariate analysis, continuous RRT modality was significantly associated with femoral site (OR = 2.33 (95% CI (1.34-4.07), p = 0.003) and higher weight with jugular site [88.9 vs 83.2 kg, OR = 0.99 (95% CI 0.98-1.00), p = 0.03]. Investigator site was also significantly associated with the choice of insertion site (p = 0.03). Cumulative incidence of catheter replacement did not differ between jugular and femoral site [sHR 0.90 (95% CI 0.64-1.25), p = 0.67]. Catheter dysfunction was the main reason for replacement (n = 47), followed by suspected infection (n = 29) which was actually seldom proven (n = 4). No mechanical complication (pneumothorax or hemothorax) occurred.

CONCLUSION

Femoral site was preferentially used in this prospective study of RRT catheters in 31 French intensive care units. The choice of insertion site depended on investigating center habits, weight, RRT modality. A high incidence of catheter infection suspicion led to undue replacement.

Surface modification strategies for hemodialysis catheters to prevent catheter-related infections: A review

Insertion of a central venous catheter is one of the most common invasive procedures applied in hemodialysis therapy for end-stage renal disease. The most important complication of a central venous catheter is catheter-related infections that increase hospitalization and duration of intensive care unit stay, cost of treatment, mortality, and morbidity rates. Pathogenic microorganisms, such as, bacteria and fungi, enter the body from the catheter insertion site and the surface of the catheter can become colonized. The exopolysaccharide-based biofilms from bacterial colonies on the surface are the main challenge in the treatment of infections. Catheter lock solutions and systemic antibiotic treatment, which are commonly used in the treatment of hemodialysis catheter-related infections, are insufficient to prevent and terminate the infections and eventually the catheter needs to be replaced. The inadequacy of these approaches in termination and prevention of infection revealed the necessity of coating of hemodialysis catheters with bactericidal and/or antiadhesive agents. Silver compounds and nanoparticles, anticoagulants (e.g., heparin), antibiotics (e.g., gentamicin and chlorhexidine) are some of the agents used for this purpose. The effectiveness of few commercial hemodialysis catheters that were coated with antibacterial agents has been tested in clinical trials against catheter-related infections of pathogenic bacteria, such as Staphylococcus aureus and Staphylococcus epidermidis with promising results. Novel biomedical materials and engineering techniques, such as, surface micro/nano patterning and the conjugation of antimicrobial peptides, enzymes, metallic cations, and hydrophilic polymers (e.g., poly [ethylene glycol]) on the surface, has been suggested recently.

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.

Dialysis catheters in the ICU: selection, insertion and maintenance

PURPOSE OF REVIEW

Choosing the best catheter for renal replacement therapy (RRT) is not an easy task. Beyond catheter length, many of its properties can influence effectiveness of the RRT session. Maintenance between sessions, particularly the locking solution, also impacts catheter lifespan and infection rates.

RECENT FINDINGS

Many innovations in dialysis catheters have been proposed by the industry over the past decade, including the material used, the shape of the lumens and the position of the inflow and outflow holes. Impregnated catheters have also been developed to prevent catheter-related infections. Many locking solutions are available, either for maintaining catheter patency or for preventing infections.

SUMMARY

Although studies conducted in the specific context of the ICU are still scarce, some conclusions can be drawn. Catheter length must be adapted to the insertion site to reach an area of high blood flow. Kidney-shape lumens appear to be less thrombogenic and seem to prevent catheter dysfunction. Catheter tip and lumen holes also affect catheter function. For catheter locking, 4% citrate appears nowadays as one of the best options, but taurolidine-based solutions are also interesting.

Common errors in temporary hemodialysis catheter insertion

Non-tunneled hemodialysis catheter (NTHC) insertion is an essential skill for nephrology practice and remains a requirement of training. However, improper insertion technique can increase the risk of potentially fatal infectious and mechanical complications. Evidence-based strategies can reduce the rates of such complications and should be integrated into practice and training. Ultrasound (US) guidance should routinely be used for NTHC insertion at the femoral and internal jugular sites (with avoidance of the subclavian site). Nephrologists should receive proper training in the use of US for line insertion. With respect to other aspects of the procedure, proper insertion technique readily prevents guidewire-induced arrhythmias. In addition, adherence to infection-control guidelines results in a sustainable reduction in bloodstream infections. All these aspects of NTHC insertion may be best taught and evaluated through a program that includes simulation-based mastery learning (SBML) training. As a separate issue, nephrologists (and intensivists) should be aware that a dysfunctional catheter should be replaced at a new site rather than being changed over a guidewire. This review of common errors related to NTHC insertion seeks to highlight evidence-based approaches to practice and training.

Availability of right femoral vein as a route for tunneled hemodialysis catheterization

Purpose

This study was performed to investigate the primary patency rate and catheter-related problems associated with use of the femoral vein as a route for tunneled hemodialysis catheterization compared with those of the right internal jugular vein as the first-choice route in patients undergoing maintenance hemodialysis.

Patients and methods

Twenty-two patients underwent placement of indwelling tunneled hemodialysis catheters in the right internal jugular vein as the first option for maintenance hemodialysis, and 20 patients underwent placement in the right femoral vein as the second option. The primary patency rate of the catheters and catheter-related problems at 1, 3, 6, and 12 months after placement were investigated.

Results

The 1-, 3-, 6-, and 12-month primary patency rates of the tunneled hemodialysis catheters in the right internal jugular vein were 95.5%, 95.5%, 81.3%, and 58.3%. The primary patency rates of the catheters in the right femoral vein were 95.0%, 89.5%, 86.7%, and 66.7%. There were no statistically significant differences in the primary patency rates at 1, 3, 6, and 12 months or in catheter-related problems between the right internal jugular vein and right femoral vein.

Conclusion

The primary patency rate and catheter-related problems of indwelling tunneled hemodialysis catheters placed in the right femoral vein were not different from those in the right internal jugular vein in patients undergoing maintenance hemodialysis. These results suggest that the right femoral vein might be a useful option for placement of indwelling tunneled hemodialysis catheters in patients undergoing maintenance hemodialysis.

Acute kidney injury in the ICU: from injury to recovery: reports from the 5th Paris International Conference

The French Intensive Care Society organized its yearly Paris International Conference in intensive care on June 18-19, 2015. The main purpose of this meeting is to gather the best experts in the field in order to provide the highest quality update on a chosen topic. In 2015, the selected theme was: "Acute Renal Failure in the ICU: from injury to recovery." The conference program covered multiple aspects of renal failure, including epidemiology, diagnosis, treatment and kidney support system, prognosis and recovery together with acute renal failure in specific settings. The present report provides a summary of every presentation including the key message and references and is structured in eight sections: (a) diagnosis and evaluation, (b) old and new diagnosis tools,

Acute kidney injury in the ICU: from injury to recovery: reports from the 5th Paris International Conference

The French Intensive Care Society organized its yearly Paris International Conference in intensive care on June 18-19, 2015. The main purpose of this meeting is to gather the best experts in the field in order to provide the highest quality update on a chosen topic. In 2015, the selected theme was: "Acute Renal Failure in the ICU: from injury to recovery." The conference program covered multiple aspects of renal failure, including epidemiology, diagnosis, treatment and kidney support system, prognosis and recovery together with acute renal failure in specific settings. The present report provides a summary of every presentation including the key message and references and is structured in eight sections: (a) diagnosis and evaluation, (b) old and new diagnosis tools,

Haemodialysis catheters in the intensive care unit

Ten to 15% of critically ill patients need renal replacement therapy (RRT) for severe acute kidney injury. The dialysis catheter is critical for RRT quality and efficiency. Catheters have several properties that must be optimized to promote RRT success. The distal tip has to be located in a high blood flow location, which means central venous territory. Therefore, catheters are mostly inserted into the right internal jugular vein or in femoral veins. External diameter should vary from 12 to 16 Fr in order to ensure adequate blood flow inside the catheter. Lumen shapes are theoretically designed to limit thrombotic risk with low turbulences and frictional forces against the internal wall. With low aspiration pressure, distal tip shape has to deliver sufficient blood flow, while limiting recirculation rate. Catheter material should be biocompatible. Despite in vitro data, no strong evidence supports the use of coated catheters in the ICU in order to reduce infectious risk. Antibiotic "lock" solutions are not routinely recommended. Ultrasound guidance for catheterization significantly decreases mechanical complications. Clinicians should select the optimal catheter according to patient body habitus, catheter intrinsic properties and RRT modality to be used.

Microbiology of Non-Tunnelled Catheter-Related Infections

INTRODUCTION

Aerobic bacterial infections often complicate vascular access in patients receiving haemodialysis, leading to Catheter-Related Blood Stream Infections (CRBSI). Various studies report Gram - positive bacteria, Staphylococcus aureus (S. aureus) in particular, as the most common aetiologic agent. Studies on microbiological analysis in this subset of population from India are very few.

AIM

To examine clinical and bacteriological profiles of haemodialysis patients developing CRBSI, the antibiotic susceptibility of the bacteria isolated from these patients and determine nasal carriage of S. aureus in the study subjects.

MATERIALS AND METHODS

Using a prospective observational design 127 patients receiving haemodialysis (84 males; 43 females) from October 2011 to March 2013 were enrolled in this study. At each dialysis session, catheters were examined for any evidence of infection. In case of suspicion for infection, pus swab, blood culture and the catheter tips were sent to microbiology laboratory for site specific investigations. Vancomycin injection was empirically administered to these patients pending culture results. Data obtained was examined for relationship of CRBSI with clinical and socio-demographic risk factors.

RESULTS

Out of 127 patients, 19 developed CRBSI, 10 developed exit-site infections and 33 patients were noted to have colonization of their catheters. The most common organisms included S. aureus in 24 (45.2%) catheter tips, followed by Pseudomonas aeruginosa in 9 (17%), Acinetobacter spp. in 5 (9%), Enterobacter spp. in 4 (7.5%) and Klebsiella pneumoniae in 3 (5.6%) catheter tips. Bacteraemia was found in 19 (20.7%) patients and P. aeruginosa was the most commonly isolated organism amongst them (38.8%). Staphylococcal nasal carriage was seen in 60 (69%) patients and 36 (41.4%) of these isolates were methicillin-resistant. Significant factors associated with CRBSI included history of bacteraemia, presence of diabetes mellitus, long duration (>15 days) of catheterization and antibiotic use within three months (p<0.05 for all).

CONCLUSION

Although S. aureus was the most common colonizer of non-tunnelled central access catheters among haemodialysis patients, CRBSI was most frequently caused by P. aeruginosa, which may have a bearing on our current antibiotic policy.

Renal replacement therapy in adult and pediatric intensive care : Recommendations by an expert panel from the French Intensive Care Society (SRLF) with the French Society of Anesthesia Intensive Care (SFAR) French Group for Pediatric Intensive Care Emergencies (GFRUP) the French Dialysis Society (SFD)

Acute renal failure (ARF) in critically ill patients is currently very frequent and requires renal replacement therapy (RRT) in many patients. During the last 15 years, several studies have considered important issues regarding the use of RRT in ARF, like the time to initiate the therapy, the dialysis dose, the types of catheter, the choice of technique, and anticoagulation. However, despite an abundant literature, conflicting results do not provide evidence on RRT implementation. We present herein recommendations for the use of RRT in adult and pediatric intensive care developed with the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system by an expert group of French Intensive Care Society (SRLF), with the participation of the French Society of Anesthesia and Intensive Care (SFAR), the French Group for Pediatric Intensive Care and Emergencies (GFRUP), and the French Dialysis Society (SFD). The recommendations cover 4 fields: criteria for RRT initiation, technical aspects (access routes, membranes, anticoagulation, reverse osmosis water), practical aspects (choice of the method, peritoneal dialysis, dialysis dose, adjustments), and safety (procedures and training, dialysis catheter management, extracorporeal circuit set-up). These recommendations have been designed on a practical point of view to provide guidance for intensivists in their daily practice.

Real-time, ultrasound-guided infraclavicular axillary vein cannulation for renal replacement therapy in the critical care unit—A prospective intervention study

PURPOSE

The cannulation of the axillary vein for renal replacement therapy is a rarely performed procedure in the critical care unit. We defined the venipuncture and catheterization success rates and early mechanical complication rates of this technique in critical care patients with acute kidney injury.

MATERIALS AND METHODS

Twenty-nine mechanically ventilated patients with clinical indications for insertion of temporary hemodialysis catheters enrolled in a registered trial (NCT01919528) as a pilot cohort. We performed 29 real-time, ultrasound-guided infraclavicular axillary vein cannulation attempts for renal replacement therapy. We defined the venipuncture and catheterization success rates and early mechanical complication rates for this technique.

RESULTS

The puncture of the axillary vein was successful in 28 (96.5%) patients. In 22 patients (75.9%), venipuncture occurred during the first attempt and in 6 patients during the second (20.7%). The overall cannulation success rate was 93.1% (95% confidence interval, 77%-99%). We noted 6.8% potentially serious complications rate, 10.3% minor complications rate, and 0% life-threatening early mechanical complications. We achieved an 89.6% renal replacement therapy success rate and low rate of catheters malfunction.

CONCLUSIONS

Real-time, ultrasound-guided, infraclavicular axillary vein cannulation for renal replacement therapy in the critical care unit is a reliable method of dual-lumen hemodialysis catheter insertion and can be considered a reasonable alternative to jugular and femoral routes in special clinical circumstances.

Anticoagulation strategies in venovenous hemodialysis in critically ill patients: a five-year evaluation in a surgical intensive care unit

Renal failure is a common complication among critically ill patients. Timing, dosage, and mode of renal replacement (RRT) are under debate, but also anticoagulation strategies and vascular access interfere with dialysis success. We present a retrospective, five-year evaluation of patients requiring RRT on a multidisciplinary 50-bed surgical intensive care unit of a university hospital with special regard to anticoagulation strategies and vascular access. Anticoagulation was preferably performed with unfractionated heparin or regional citrate application (RAC). Bleeding and suspected HIT-II were most common causes for RAC. In CVVHD mode filter life span was significantly longer under RAC compared to heparin or other anticoagulation strategies (P = 0.001). Femoral vascular access was associated with reduced filter life span (P = 0.012), especially under heparin anticoagulation (P = 0.015). Patients on RAC had higher rates of metabolic alkalosis (P = 0.001), required more transfusions (P = 0.045), and showed higher illness severity measured by SOFA scores (P = 0.001). RRT with unfractionated heparin represented the most common anticoagulation strategy in this study population. However, patients with bleeding risk and severe organ dysfunction were more likely placed on RAC. Citrate provided longer filter life spans regardless of vascular access site. Attention has to be paid to metabolic disturbances.

Gender differences in randomised, controlled trials in intensive care units

There is a male dominance among patients in intensive care units (ICUs). Potentially, this will increase the risk of a skewed male/female distribution in randomised, controlled trials (RCTs). We have evaluated if this has in fact happened when randomising and whether the authors have been aware of that. We performed a systematic search on PubMed from 1 January 2011 to 31 May 2012 using the mesh terms 'randomized controlled trial' and 'intensive care unit'. Twenty-five RCTs with a total of 12,788 patients met the inclusion criteria, with an overall male dominance of 63.6% (P < 0.0001). Eighteen of the 25 papers had an individually statistically significant gender difference in their total trial population. None of the 18 trials with a significant gender difference in their overall trial population had calculated the P-value for this overall difference. In the randomised groups, there was a significant gender difference in five papers. Seventeen had no significant gender difference in the randomised groups, and three papers did not state gender in the randomised groups. This study show that there is a marked male dominance in RCTs conducted in ICUs. We recommend that when planning future RCTs, the authors contemplate if their results can be used indiscriminately among ICU patients if the distribution of males and females is much skewed. It is relevant to determine if ones endpoint can be influenced by gender differences and if there is a risk of gender influence on data, proportional allocation or stratification should be considered.

Quasi-experimental study of sodium citrate locks and the risk of acute hemodialysis catheter infection among critically ill patients

Critically ill patients who require renal replacement therapy (RRT) are vulnerable to catheter-related bloodstream infections (CRBSI). This study compared the risks of dialysis catheter infection according to the choice of locking solution in the intensive care unit (ICU). A prospective quasi-experimental study with marginal structural models (MSM) and 2:1 greedy propensity-score matching (PSM) was conducted at nine university-affiliated hospitals and three general hospitals. A total of 596 critically ill patients received either saline solution or heparin lock solution (the standard of care [SOC]) from 2004 to 2007 in the Cathedia cohort (n = 464 for MSM; n = 124 for PSM) or 46.7% citrate lock from 2011 to 2012 in the citrate (CLock) cohort (n = 132 for MSM; n = 62 for PSM) to perform RRT using intermittent hemodialysis. Catheter-tip colonization and CRBSI were analyzed. The mean duration (standard deviation [SD]) of catheterization was 7.1 days (6.1) in the SOC group and 7.0 days (5.9) in the CLock group (P = 0.84). The risk of dialysis catheter-tip colonization was lower in the CLock group (20.5 versus 38.7 per 1,000 catheter-days in the SOC group; hazard ratio [HR] from MSM, 0.73; 95% confidence interval [CI], 0.57 to 0.93; P < 0.02). Consistent findings were found from PSM (HR, 0.46; 95% CI, 0.22 to 0.95; P < 0.04). The risk of CRBSI was nonsignificantly different in the CLock group (1.1 versus 1.8 per 1,000 catheter-days in the SOC group; HR from MSM, 0.48; 95% CI, 0.12 to 1.87; P = 0.29). By reducing the risk of catheter-tip colonization, citrate lock has the potential to improve hemodialysis safety in the ICU. Additional studies are warranted before the routine use of citrate locks can be recommended in the ICU.

Initial and extended use of femoral versus nonfemoral double-lumen vascular catheters and catheter-related infection during continuous renal replacement therapy

BACKGROUND

The risk of catheter-related infection or bacteremia, with initial and extended use of femoral versus nonfemoral sites for double-lumen vascular catheters (DLVCs) during continuous renal replacement therapy (CRRT), is unclear.

STUDY DESIGN

Retrospective observational cohort study.

SETTING & PARTICIPANTS

Critically ill patients on CRRT in a combined intensive care unit of a tertiary institution.

FACTOR

Femoral versus nonfemoral venous DLVC placement.

OUTCOMES

Catheter-related colonization (CRCOL) and bloodstream infection (CRBSI).

MEASUREMENTS

CRCOL/CRBSI rates expressed per 1,000 catheter-days.

RESULTS

We studied 458 patients (median age, 65 years; 60% males) and 647 DLVCs. Of 405 single-site only DLVC users, 82% versus 18% received exclusively 419 femoral versus 82 jugular or subclavian DLVCs, respectively. The corresponding DLVC indwelling duration was 6±4 versus 7±5 days (P=0.03). Corresponding CRCOL and CRBSI rates (per 1,000 catheter-days) were 9.7 versus 8.8 events (P=0.8) and 1.2 versus 3.5 events (P=0.3), respectively. Overall, 96 patients with extended CRRT received femoral-site insertion first with subsequent site change, including 53 femoral guidewire exchanges, 53 new femoral venipunctures, and 47 new jugular/subclavian sites. CRCOL and CRBSI rates were similar for all such approaches (P=0.7 and P=0.9, respectively). On multivariate analysis, CRCOL risk was higher in patients older than 65 years and weighing >90kg (ORs of 2.1 and 2.2, respectively; P<0.05). This association between higher weight and greater CRCOL risk was significant for femoral DLVCs, but not for nonfemoral sites. Other covariates, including initial or specific DLVC site, guidewire exchange versus new venipuncture, and primary versus secondary DLVC placement, did not significantly affect CRCOL rates.

LIMITATIONS

Nonrandomized retrospective design and single-center evaluation.

CONCLUSIONS

CRCOL and CRBSI rates in patients on CRRT are low and not influenced significantly by initial or serial femoral catheterizations with guidewire exchange or new venipuncture. CRCOL risk is higher in older and heavier patients, the latter especially so with femoral sites.

Temporary hemodialysis catheters: recent advances

The insertion of non-tunneled temporary hemodialysis catheters (NTHCs) is a core procedure of nephrology practice. While urgent dialysis may be life-saving, mechanical and infectious complications related to the insertion of NTHCs can be fatal. In recent years, various techniques that reduce mechanical and infectious complications related to NTHCs have been described. Evidence now suggests that ultrasound guidance should be used for internal jugular and femoral vein NTHC insertions. The implementation of evidence-based infection-control ‘bundles' for central venous catheter insertions has significantly reduced the incidence of bloodstream infections in the intensive care unit setting with important implications for how nephrologists should insert NTHCs. In addition, the Cathedia Study has provided the first high-level evidence about the optimal site of NTHC insertion, as it relates to the risk of infection and catheter dysfunction. Incorporating these evidence-based techniques into a simulation-based program for training nephrologists in NTHC insertion has been shown to be an effective way to improve the procedural skills of nephrology trainees. Nonetheless, there are some data suggesting nephrologists have been slow to adopt evidence-based practices surrounding NTHC insertion. This mini review focuses on techniques that reduce the complications of NTHCs and are relevant to the practice and training of nephrologists.

Use of tissue plasminogen activator in catheters used for extracorporeal renal replacement therapy

Background

Intraluminal thrombosis of central venous catheters used for renal replacement therapy (RRT) decreases the ability to provide adequate treatment. Alteplase is a recombinant tissue plasminogen activator that has been used to improve the function of catheters used for RRT in humans.

Objectives

To retrospectively review alteplase instillation in dysfunctional catheters used for RRT in dogs and cats.

Animals

Seventeen dogs and 8 cats receiving RRT for kidney failure.

Methods

Medical records of patients in which alteplase was used for RRT catheter dysfunction from 2004 to 2012 were retrospectively reviewed to characterize reasons for use, improvement in function, increase in blood flow, and duration of improvement.

Results

Alteplase was instilled 43 times in 29 catheters, most commonly because of suspicion that the catheter would not provide sufficient flow on the next treatment (n = 21). The second most common reason was inability to start a dialysis treatment (n = 12). Catheter function improved after alteplase instillation in 34 of 43 treatments (79%). Median blood flow rate increased by 13% (18 mL/min) in the dialysis session after alteplase instillation. Seven of 29 catheters (24%) were treated with alteplase on >1 occasion (median time to second treatment, 8 days), and 1 catheter had to be replaced because of intractable dysfunction.

Conclusions and Clinical Importance

Alteplase is effective at improving function of central venous catheters used to provide RRT, but the results are short‐lived.

Clinically manifest thromboembolic complications of femoral vein catheterization for continuous renal replacement therapy

PURPOSE

The safety of femoral vein (FV) catheterization for continuous renal replacement therapy is uncertain. We sought to determine the incidence of clinically manifest venous thromboembolism (VTE) in such patients.

METHODS

We retrospectively studied patients with femoral high flow catheters (≥ 13F) (December 2005 to February 2011). Discharge diagnostic codes were independently screened for VTE. The incidence of VTE was also independently similarly assessed in a control cohort of patients ventilated for more than 2 days (January 2011 to December 2011) in the same intensive care unit (ICU).

RESULTS

We studied 380 patients. Their mean age was 61 years, and 59% were male. The mean Acute Physiology and Chronic Health Evaluation III score was 84; average duration of continuous renal replacement therapy was 74 hours, and 232 patients (61%) survived to hospital discharge with an average length of hospital stay of 22 days. Only 5 patients (1.3%) had clinically manifest VTE after FV catheterization. In the control cohort of 514 ICU patients, the incidence of VTE was 4.4% (P < .05 compared with FV group).

CONCLUSION

The incidence of clinically manifest VTE after FV catheterization with high flow catheters is low and lower to that seen in general ICU patients.

How to deal with dialysis catheters in the ICU setting

Acute kidney insufficiency (AKI) occurs frequently in intensive care units (ICU). In the management of vascular access for renal replacement therapy (RRT), several factors need to be taken into consideration to achieve an optimal RRT dose and to limit complications. In the medium and long term, some individuals may become chronic dialysis patients and so preserving the vascular network is of major importance. Few studies have focused on the use of dialysis catheters (DC) in ICUs, and clinical practice is driven by the knowledge and management of long-term dialysis catheter in chronic dialysis patients and of central venous catheter in ICU patients. This review describes the appropriate use and management of DCs required to obtain an accurate RRT dose and to reduce mechanical and infectious complications in the ICU setting. To deliver the best RRT dose, the length and diameter of the catheter need to be sufficient. In patients on intermittent hemodialysis, the right internal jugular insertion is associated with a higher delivered dialysis dose if the prescribed extracorporeal blood flow is higher than 200 ml/min. To prevent DC colonization, the physician has to be vigilant for the jugular position when BMI < 24 and the femoral position when BMI > 28. Subclavian sites should be excluded. Ultrasound guidance should be used especially in jugular sites. Antibiotic-impregnated dialysis catheters and antibiotic locks are not recommended in routine practice. The efficacy of ethanol and citrate locks has yet to be demonstrated. Hygiene procedures must be respected during DC insertion and manipulation.