Early Net Ultrafiltration during Continuous Renal Replacement Therapy: Impact of Admission Diagnosis and Association with Mortality

INTRODUCTION

Continuous renal replacement therapy (CRRT) is common in the intensive care unit (ICU) but a high net ultrafiltration rate (UFNET) calculated with daily data may increase mortality. We aimed to study early UFNET practice using minute-by-minute CRRT machine recordings and to assess its association with admission diagnosis and mortality.

METHODS

We studied CRRT treatments in three adult ICUs over 7 years. We calculated early UFNET rates minute-by-minute and categorized UFNET into tertiles of mean UFNET in the first 72 h and admission diagnosis. We applied Cox-proportional hazards modelling with censoring of patients who died within 72 h.

RESULTS

We studied 1,218 patients, 154,712 h, and 9,282,729 min of CRRT (5,702 circuits). Mean early UFNET was 1.52 (1.46-1.57) mL/kg/h. Early UFNET tertiles were similar to, but somewhat higher than, previously reported values at 0.00-1.20 mL/kg/h, 1.21-1.93 mL/kg/h, and >1.93 mL/kg/h. UFNET values were similar whether evaluated at 24 or 72 h or for the entire duration of CRRT. There was, however, significant variation in UFNET practice by admission diagnosis: higher in respiratory diseases (pneumonia p = 0.01, other p < 0.0001) and cardiovascular disease (p = 0.005) but lower in cardiothoracic surgery (p = 0.04), renal (p = 0.0003) and toxicology-associated diagnoses (p = 0.01). Higher UFNET was associated with an increased hazard of death, HR 1.24 (1.13-1.37), independent of admission diagnosis, weight, age, sex, presence of end-stage kidney disease, and severity of illness.

CONCLUSION

Early UFNET practice varies significantly by admission diagnosis. Higher early UFNET is independently associated with mortality. Impacts of UFNET on mortality may vary by admission diagnosis. Further work is required to elucidate the nature and mechanisms responsible for this association.

Pseudo-outbreak of haemodiafiltration dialysis fluid contamination: results of a detailed epidemiologic investigation

Background

Compliance with dialysis fluid ultrapurity standards is a paramount for online modalities. More than 200 dialysis fluid samples have been analyzed monthly for years in our two dialysis units, with compliant microbiological results until mid-2020.

Aim

In mid-2020, an unusual occurrence (30%) of contaminated dialysis fluids in dialysis units led us to investigate to determine the source.

Methods

Microbiological methods for aquaphilic bacteria culturing and endotoxin detection in dialysis fluids were routinely performed on a monthly basis for all dialysis machines. As the contamination appeared randomly and almost simultaneously in our two units without any routine change or febrile syndrome, we searched for a common cause. Supplier's sampling kits as well as microbiological laboratory procedures were scrupulously investigated.

Findings

21 out of 30 sampling bags filled with sterile water brought back numerous fungi and bacteria. Laboratory's investigation, through the negative control tests performed routinely, exonerated the lab. All batches of bags analyzed later showed variable levels of contamination according to their transport/storage mode or date of manufacturing. Analyses performed by the supplier - methods complying with the medical device's standards but different from those recommended for dialysis fluids purity - remained negative.

Conclusion

Our investigation revealed that the contamination of our sampling kits came presumably from the manufacturer's supplying chain. Such false-positive results findings, created serious safety issues and disturbed clinical activities since positive machines were quarantined. Furthermore, it raised a serious concern about manufacturing, microbiological checking and shipping methods for the medical device industry that deserve further attention.

Continuous Renal Replacement Therapy during Extracorporeal Membrane Oxygenation: Circuit Haemodynamics and Circuit Failure

INTRODUCTION

Treatment with continuous renal replacement therapy (CRRT) is common during extracorporeal membrane oxygenation (ECMO). Such ECMO-CRRT has specific technical characteristics, which may affect circuit life. Accordingly, we studied CRRT haemodynamics and circuit life during ECMO.

METHODS

ECMO and non-ECMO-CRRT treatments in two adult intensive care units were compared using data collected over a 3-year period. A potential predictor of circuit survival identified in a 60% training data subset as a time-varying covariate within a Cox proportional hazard model was subsequently assessed in the complementary remaining data (40%).

RESULTS

Median [interquartile range] CRRT circuit life was greater when associated with ECMO (28.8 [14.0-65.2] vs. 20.2 [9.8-40.2] h, p &lt; 0.0001). Access, return, prefilter, and effluent pressures were also greater during ECMO. Higher ECMO flows were associated with higher access and return pressures. Classification and regression tree analysis identified an association between high access pressures and accelerated circuit failure, while both first access pressures ≥190 mm Hg (HR 1.58 [1.09-2.30]) and patient weight (HR 1.85 [1.15-2.97] third tertile vs. first tertile) were independently associated with circuit failure in a multivariable Cox model. Access dysfunction was associated with a stepwise increase in transfilter pressure, suggesting a potential mechanism of membrane injury.

CONCLUSION

CRRT circuits used in conjunction with ECMO have a longer circuit life than usual CRRT despite exposure to higher circuit pressures. Markedly elevated access pressures, however, may predict early CRRT circuit failure during ECMO, possibly via progressive membrane thrombosis as evidenced by increased transfilter pressure gradients.

Better Anti-Spike IgG Antibody Response to SARS-CoV-2 Vaccine in Patients on Haemodiafiltration than on Haemodialysis

INTRODUCTION

The antibody response to SARS-CoV-2 vaccine in haemodialysis (HD) patients is diminished compared to healthy subjects. The aim of this study was to compare the presence of reactive SARS-CoV-2 antibodies in patients with high-flux HD and on-line haemodiafiltration (HDF) three and 6 months after the second dose of SARS-CoV-2 vaccine since previous studies indicate that a sustained antibody response correlates with protection from disease.

METHODS

We included 216 HD patients of which 157 had on-line HDF and 59 high-flux HD and 46 health care workers as controls and studied the presence of reactive anti-spike IgG antibodies three and 6 months after the second dose of SARS-CoV-2 vaccine. Clinical features between the patient groups were similar, but patients with on-line HDF had significantly higher Kt/V.

RESULTS

The percentage of participants with reactive antibodies was significantly lower in patients compared to controls, both three and 6 months after the second dose of vaccine. Furthermore, the proportion of patients with reactive anti-spike IgG ≥1.0 6 months after the second dose of vaccine was significantly higher in patients with on-line HDF compared to in patients with high-flux HD. In logistic regression analyses adjusted for several clinical features, the variables associated with presence of reactive anti-spike IgG at 3 months after the second dose of vaccine were lower age, HDF treatment, not being obese and not having a previous solid organ transplant. The two variables with the strongest influence on the presence of reactive anti-spike IgG levels 6 months after the second dose of vaccine were treatment with on-line HDF and not having immunosuppressive therapy.

CONCLUSION

This is the first study to show that on-line HDF preserves the antibody response better than high-flux HD after vaccination with SARS-CoV-2 vaccine. Treatment strategies that sustain the vaccine response are essential to apply in this vulnerable group of patients.

The high-volume haemodiafiltration vs high-flux haemodialysis registry trial (H4RT): a multi-centre, unblinded, randomised, parallel-group, superiority study to compare the effectiveness and cost-effectiveness of high-volume haemodiafiltration and high-flux haemodialysis in people with kidney failure on maintenance dialysis using linkage to routine healthcare databases for outcomes

BACKGROUND

More than a third of the 65,000 people living with kidney failure in the UK attend a dialysis unit 2-5 times a week to have their blood cleaned for 3-5 h. In haemodialysis (HD), toxins are removed by diffusion, which can be enhanced using a high-flux dialyser. This can be augmented with convection, as occurs in haemodiafiltration (HDF), and improved outcomes have been reported in people who are able to achieve high volumes of convection. This study compares the clinical- and cost-effectiveness of high-volume HDF compared with high-flux HD in the treatment of kidney failure.

METHODS

This is a UK-based, multi-centre, non-blinded randomised controlled trial. Adult patients already receiving HD or HDF will be randomised 1:1 to high-volume HDF (aiming for 21+ L of substitution fluid adjusted for body surface area) or high-flux HD. Exclusion criteria include lack of capacity to consent, life expectancy less than 3 months, on HD/HDF for less than 4 weeks, planned living kidney donor transplant or home dialysis scheduled within 3 months, prior intolerance of HDF and not suitable for high-volume HDF for other clinical reasons. The primary outcome is a composite of non-cancer mortality or hospital admission with a cardiovascular event or infection during follow-up (minimum 32 months, maximum 91 months) determined from routine data. Secondary outcomes include all-cause mortality, cardiovascular- and infection-related morbidity and mortality, health-related quality of life, cost-effectiveness and environmental impact. Baseline data will be collected by research personnel on-site. Follow-up data will be collected by linkage to routine healthcare databases - Hospital Episode Statistics, Civil Registration, Public Health England and the UK Renal Registry (UKRR) in England, and equivalent databases in Scotland and Wales, as necessary - and centrally administered patient-completed questionnaires. In addition, research personnel on-site will monitor for adverse events and collect data on adherence to the protocol (monthly during recruitment and quarterly during follow-up).

DISCUSSION

This study will provide evidence of the effectiveness and cost-effectiveness of HD as compared to HDF for adults with kidney failure in-centre HD or HDF. It will inform management for this patient group in the UK and internationally.

TRIAL REGISTRATION

ISRCTN10997319 . Registered on 10 October 2017.

Distinct Solute Removal Patterns by Similar Surface High-Flux Membranes in Haemodiafiltration: The Adsorption Point of View

INTRODUCTION

Haemodialysis (HD) allow depuration of uraemic toxins by diffusion, convection, and adsorption. Online haemodiafiltration (HDF) treatments add high convection to enhance removal. There are no prior studies on the relationship between convection and adsorption in HD membranes. The possible benefits conferred by intrinsic adsorption on protein-bound uraemic toxins (PBUTs) removal are unknown.

METHODS

Twenty-two patients underwent their second 3-days per week HD sessions with randomly selected haemodialysers (polysulfone, polymethylmethacrylate, cellulose triacetate, and polyamide copolymer) in high-flux HD and HDF. Blood samples were taken at the beginning and at the end of the treatment to assess the reduction ratio (RR) in a wide range of molecular weight uraemic toxins. A mid-range removal score (GRS) was also calculated. An elution protocol was implemented to quantify the amount of adsorbed mass (Mads) for each molecule in every dialyser.

RESULTS

All synthetic membranes achieved higher RR for all toxins when used in HDF, specially the polysulfone haemodialyser, resulting in a GRS = 0.66 ± 0.06 (p < 0.001 vs. cellulose triacetate and polyamide membranes). Adsorption was slightly enhanced by convection for all membranes. The polymethylmethacrylate membrane showed expected substantial adsorption of β2-microglobulin (MadsHDF = 3.5 ± 2.1 mg vs. MadsHD = 2.1 ± 0.9 mg, p = 0.511), whereas total protein adsorption was pronounced in the cellulose triacetate membrane (MadsHDF = 427.2 ± 207.9 mg vs. MadsHD = 274.7 ± 138.3 mg, p = 0.586) without enhanced PBUT removal.

DISCUSSION/CONCLUSION

Convection improves removal and slightly increases adsorption. Adsorbed proteins do not lead to enhanced PBUTs depuration and limit membrane efficiency due to fouling. Selection of the correct membrane for convective therapies is mandatory to optimize removal efficiency.

High-volume online haemodiafiltration treatment and outcome of end-stage renal disease patients: more than one mode

The reduction of the dismally high mortality of current end-stage renal disease patients maintained on conventional standard haemodialysis (HD) remains an unmet medical need. Online haemodiafiltration (HDF) modes with various sites of fluid substitution (post-, pre-, mixed- and mid-dilution) are increasingly used worldwide as promising alternatives to conventional HD. Large scale cohort studies, post hoc analyses of randomized trials, and individual participant meta-analyses suggest that post-dilution and pre-dilution, especially with high substitution volumes, improve outcomes compared with conventional standard HD. However, there is no definitive proof of a survival advantage of HDF over standard HD. The different modes of high-volume HDF should be considered a therapeutic platform allowing to personalize and tailor routine HDF treatment. The selection of the HDF mode should be made according to individual patient characteristics. Utilizing high retention onset membranes, expanded haemodialysis (HDx) can achieve the same solute removal performance as HDF. Subgroups of high-volume OL-HDF patients could benefit from HDx. Ongoing and future trials should provide definitive proof for the superiority of high-volume OL-HDF over conventional HD or HDx to give guidance for the most favourable mode of dialytic therapy for clinical use.

Haemodiafiltration use in children: data from the Italian Pediatric Dialysis Registry

BACKGROUND

High volume haemodiafiltration (HDF) is associated with better survival than conventional haemodialysis (HD) in adults, but data concerning its use in children are lacking. The aim of this study was to assess the prevalence of paediatric HDF use and its associated factors in recent years in Italy.

METHODS

We retrospectively reviewed the files of patients from the Italian Pediatric Dialysis Registry's database who were registered between January 1, 2004 and December 31, 2016 and treated with extracorporeal dialysis for at least 6 months, looking in particular at modality and its associated factors.

RESULTS

One hundred forty-one out of 198 patients were treated exclusively with bicarbonate HD (71.2%), 57 with HDF (28.8%). Patients treated with HDF were younger (median 9.7 vs 13.2 years, p = 0.0008), were less often incident patients (52.6% vs 75.9%, p = 0.0031), had longer duration of the HD cycle (26.9 vs 20.8 months, p = 0.0036) and had a longer time to renal transplantation (32 vs 25 months, p = 0.0029) than those treated with bicarbonate HD only. The percentage of patients treated with HDF increased with dialysis vintage (16.9% at 6 months, 38.1% after more than 2 years of dialysis). The use of HDF was stable over time and was more common in the largest centres.

CONCLUSIONS

Over the observation period, HDF use in Italy has been limited to roughly a quarter of patients on extracorporeal dialysis, in particular to those with high dialysis vintage, younger age or a long expected waiting time to renal transplantation.

Perspectives in renal replacement therapy: Haemodialysis

Haemodialysis (HD) was the first procedure that had demonstrated the ability to partially replace renal function, and became the most widely utilized treatment for patients with end-stage renal disease (ESRD). In a great majority of countries around the world, conventional in-centre HD had become the predominant renal replacement therapy, being touted as able to achieve better solute clearance and more successful in attaining euvolemia than patients on peritoneal dialysis. This is despite the antecedent hemodynamic risks, more rapid loss of residual renal function, greater infectious perils, excessive erythropoietin requirements and higher infrastructure costs. In addition, quality of life had been suggested to be worse among patients on HD, though this had been challenged repeatedly. Consequently, the concept of integrated ESRD care over the last few decades had placed HD, as a complementary rather than a competitive treatment modality to the entire armamentarium of renal replacement therapies. Incorporating HD as part of integrated care into health-care policies and national resource planning will become an essential strategy in improving access and outcome to care among the ESRD population. The improvement in technologies and innovation in prescription had brought forth enhanced dialyzer membrane and machine upgrades, and expanded modalities including more frequent HD and haemodiafiltration. While boasting of controversial improvement in outcomes, many of these therapies remain expensive and insurmountable for widespread utility in many countries. In addition, the results of these new technologies had been conflicting across studies, with some even suggesting that they could be detrimental. Therefore, judicial consideration has to be undertaken to appropriate their use in clinical practice.

High convective volumes are associated with improvement in metabolic profile in diabetic patients on online haemodiafiltration

BACKGROUND AND OBJECTIVE

Online haemodiafiltration (OL-HDF) with high convective transport volumes improves patient survival in haemodialysis. Limiting the amount of convective volume has been proposed in patients with diabetes mellitus due to glucose load that is administered with replacement fluid. The objective of the study was to analyse the influence of substitution volume on the evolution of the metabolic profile and body composition of incident diabetic patients on OL-HDF.

MATERIAL AND METHODS

Prospective observational study in 29 incident diabetic patients on postdilution OL-HDF. Baseline data included clinical and demographic data, laboratory parameters (metabolic, nutritional and inflammatory profile) and body composition with bioimpedance spectroscopy (BIS). Laboratory parameters and mean substitution volume per session were collected every 4 months, and in 23 patients a further BIS was performed after a minimum of one year. Variations in glycosylated haemoglobin (HbA1c), triglycerides, total cholesterol, LDL-c, HDL-c, albumin, prealbumin and C reactive protein (CRP) were calculated at one year, 2 years, 3 years, and at the end of follow-up. Quarterly and annual variations were calculated as independent periods, and changes in body composition were analysed.

RESULTS

Age at baseline was 69.7±13.6 years, 62.1% were male, 72.3±13.9kg, 1.78±0.16m², with 48 (35.5-76) months on dialysis. Approximately 81.5% received insulin, 7.4% antidiabetic drugs and 51.9% statins. Mean substitution volume was 26.9±2.9L/session and follow-up period (time on OL-HDF) was 40.4±26 months. A significant correlation was observed between mean substitution volume and the increase in HDL-c (r=0.385, p=0.039) and prealbumin levels (r=0.404, p=0.003) throughout follow-up. Moreover, substitution volume was correlated with a reduction in CRP levels at one year (r=-0.531, p=0.005), 2 years (r=-0.463, p=0.046), and at the end of follow-up (r=-0.498, p=0.007). Patients with mean substitution volume >26.9L/session had a higher reduction in triglycerides and CRP, and an increase in HDL-c levels. These patients with >26.9L/session finished the study with higher HDL-c (48.1±9.4mg/dL vs. 41.2±11.6mg/dL, p=0.025) and lower CRP levels (0.21 [0.1-2.22] mg/dL vs. 1.01 [0.15-6.96] mg/dL, p=0.001), with no differences at baseline. Quarterly comparisons between substitution volume and laboratory changes [n=271] showed a significant correlation with a reduction in HbA1c (r=-0.146, p=0.021). Similar findings were obtained with annual comparisons [n=72] (r=-0.237, p=0.045). An annual mean substitution volume over 26.6L/session (29.3±1.7L/session vs. 23.9±1.9L/session) was associated with a reduction in HbA1c (-0.51±1.24% vs. 0.01±0.88%, p=0.043). No correlation was observed between substitution volume and changes in weight, body mass index or BIS parameters.

CONCLUSION

There is not enough evidence to restrict convective transport in diabetic patients on OL-HDF due to the glucose content of the replacement fluid.

The Novel PrisMax Continuous Renal Replacement Therapy System in a Multinational, Multicentre Pilot Setting

BACKGROUND/AIMS

We assessed how the novel PrisMax continuous renal replacement therapy (CRRT) system performed in a prospective international multicentre setting. We compared this device to its predecessor, the Prismaflex, with regards to multiple treatment parameters. Additionally, we performed a survey, aiming to measure user satisfaction.

METHODS

Data was prospectively collected from 7 intensive care units (ICU) in 6 countries. The PrisMax device data logs constituted the raw material. Clinical parameters like treatment time, filter life span, downtime, delivered dose and number and type of alarms were recorded. A user questionnaire was sent out to 3 of the participating ICUs.

RESULTS

Filter life, downtime, blood pump stops, bag changing time and number of malfunction alarms showed significantly improved values compared to the historic Prismaflex data. The survey showed high scores with regards to user friendliness.

CONCLUSION

The PrisMax CRRT device is safe and outperformed its' previous generation counterpart in virtually all aspects. Video Journal Club "Cappuccino with Claudio Ronco" at http://www.karger.com/?doi=489213.

Enhancing dialyser clearance-from target to development

Products of metabolism accumulate in kidney failure and potentially have toxic effects. Traditionally these uraemic toxins are classified as small, middle-sized and protein-bound toxins, and clearance during dialysis is affected by diffusion, convection and adsorption. As current dialysis practice effectively clears small solutes, increasing evidence supports a toxic effect for middle-sized and protein-bound toxins. Therefore, newer approaches to standard dialysis practice are required to look beyond urea clearance. Current dialysers have been developed to effectively clear small solutes and secondly to increase middle-sized toxin clearances. However, there is no ideal dialyser which can effectively clear all uraemic toxins. Advances in nanotechnology have led to improvements in manufacturing, with the production of smoother membrane surfaces and uniformity of pore size. The introduction of haemodiafiltration has led to changes in dialyser design to improve convective clearances. Both diffusional and convectional clearances can be increased by changing dialyser designs to alter blood and dialysate flows, and novel dialyser designs using microfluidics offer more efficient solute clearances. Adjusting surface hydrophilicity and charge alter adsorptive properties, and greater clearance of protein-bound toxins can be achieved by adding carbon or other absorptive monoliths into the circuit or by developing composite dialyser membranes. Other strategies to increase protein-bound toxins clearances have centred on disrupting binding and so displacing toxins from proteins. Just as the hollow fibre design replaced the flat plate dialyser, we are now entering a new era of dialyser designs aimed to increase the spectrum of uraemic toxins which can be cleared by dialysis.

Haemodiafiltration elicits less platelet activation compared to haemodialysis

Background

Mortality in patients with end-stage renal disorders is often a consequence of cardiovascular complications. Renal replacement therapies may contribute to this morbidity by promoting cellular activation. In renal failure patients peripheral blood samples were investigated for platelet and endothelial cell activation markers to compare the effects of haemodiafiltration (HDF) and haemodialysis (HD).

Methods

Overall 28 patients were included in the study. Platelet P-selectin and leukocyte - platelet heterotypic aggregates were studied by flow cytometry. Soluble P- and E-selectin values were determined by ELISA, while von Willebrand factor (vWF) antigen levels were measured by immunoturbidimetry. Statistical analysis was done by the SPSS v22 software.

Results

Platelet surface P-selectin was below 3.0 % in healthy controls, but it was higher during the dialysis after 4 h, 8 % and 14.3 % in HDF and HD, respectively. Monocyte-platelet heterotypic aggregates were significantly elevated after 4 h in both treatments, up to 69.2 % in HDF and to 82.9 % in HD. Soluble P-selectin levels were also significantly elevated by the end of both treatment procedures (p < 0.001), vWF antigen values, however, showed elevation only during HD treatment.

Conclusions

The attenuated platelet activating effects of HDF compared to HD may contribute to a less unfavourable vascular effect in this treatment modality.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-016-0364-x) contains supplementary material, which is available to authorized users.

Chronic haemodialysis in small children: a retrospective study of the Italian Pediatric Dialysis Registry

BACKGROUND

Chronic haemodialysis (HD) in small children has not been adequately investigated.

METHODS

This was a retrospective investigation of the use of chronic HD in 21 children aged  <2 years (n = 12 aged <1 year) who were registered in the Italian Pediatric Dialysis Registry. Data collected over a period of >10 years were analysed.

RESULTS

The median age of the 21 children at start of HD was 11.4 [interquartile range (IQR) 6.2-14.6] months, and HD consisted mainly of haemodiafiltration for 3-4 h in  ≥4 sessions/week. A total of 51 central venous catheters were placed, and the median survival of tunnelled and temporary lines was 349 and 31 days, respectively (p  < 0.001). Eight children (38 %) showed evidence of central vein thrombosis. Although 19 % of patients received growth hormone and 63.6 % received enteral feeding, the weight and height of these patients remained suboptimal. During the HD period the haemoglobin level increased in all patients, but not to normal levels (from 8.5 to 9.6 g/dl) despite erythropoietin administration (503-600 U/kg/week). The hospitalisation rate was 1.94/patient-year. Seventeen patients underwent renal transplantation at a median age of 3.0 years. Four patients, all affected by severe comorbidities, died during follow-up (in 2 cases due to absence of a vascular access). The 5- and 10-year cumulative survival was 82.4 and 68.7 %, respectively.

CONCLUSIONS

Extracorporeal dialysis is feasible in children aged  <2 years, but comorbidities, vascular access, growth and anaemia remain major concerns.