Prefilter Replacement Research Articles

Switching from continuous veno-venous hemodiafiltration to intermittent sustained low-efficiency daily hemodiafiltration (SLED-f) in pediatric acute kidney injury: A prospective cohort study.

Continuous kidney replacement therapy (CKRT) is the preferred modality in critically ill children with acute kidney injury. Upon improvement, intermittent hemodialysis is usually initiated as a step-down therapy, which can be associated with several adverse events. Hybrid therapies such as Sustained low-efficiency daily dialysis with pre-filter replacement (SLED-f) combines the slow sustained features of a continuous treatment, ensuring hemodynamic stability, with similar solute clearance along with the cost effectiveness of conventional intermittent hemodialysis. We examined the feasibility of using SLED-f as a transition step-down therapy after CKRT in critically ill pediatric patients with acute kidney injury. A prospective cohort study was conducted in children admitted to our tertiary care pediatric intensive care units with multi-organ dysfunction syndrome including acute kidney injury who received CKRT for management. Those patients receiving fewer than two inotropes to maintain perfusion and failed a diuretic challenge were switched to SLED-f. Eleven patients underwent 105 SLED-f sessions (mean of 9.55 +/- 4.90 sessions per patient), as a part of step-down therapy from continuous hemodiafiltration. All (100%) our patients had sepsis associated acute kidney injury with multiorgan dysfunction and required ventilation. During SLED-f, urea reduction ratio was 64.1 +/- 5.3%, Kt/V was 1.13 +/- 0.1, and beta-2 microglobulin reduction was 42.5 +/-4%. Incidence of hypotension and requirement of escalation of inotropes during SLED-f was 18.18%. Filter clotting occurred twice in one patient. SLED-f is a safe and effective modality for use as a transition therapy between CKRT and intermittent hemodialysis in children in the PICU.

Safely correct hyponatremia with continuous renal replacement therapy: A flexible, all-purpose method based on the mixing paradigm.

Treating chronic hyponatremia by continuous renal replacement therapy (CRRT) is challenging because the gradient between a replacement fluid's [sodium] and a patient's serum sodium can be steep, risking too rapid of a correction rate with possible consequences. Besides CRRT, other gains and losses of sodium- and potassium-containing solutions, like intravenous fluid and urine output, affect the correction of serum sodium over time, known as osmotherapy. The way these fluids interact and contribute to the sodium/potassium/water balance can be parsed as a mixing problem. As Na/K/H2 O are added, mixed in the body, and drained via CRRT, the net balance of solutes must be related to the change in serum sodium, expressible as a differential equation. Its solution has many variables, one of which is the sodium correction rate, but all variables can be evaluated by a root-finding technique. The mixing paradigm is proved to replicate the established equations of osmotherapy, as in the special case of a steady volume. The flexibility to solve for any variable broadens our treatment options. If the pre-filter replacement fluid cannot be diluted, then we can compensate by calculating the CRRT blood flow rate needed. Or we can deduce the infusion rate of dextrose 5% water, post-filter, to appropriately slow the rise in serum sodium. In conclusion, the mixing model is a generalizable and practical tool to analyze patient scenarios of greater complexity than before, to help doctors customize a CRRT prescription to safely and effectively reach the serum sodium target.

A Retrospective Chart Review to Determine Hypophosphatemia Incidence and Phosphorus Supplementation Requirements in Patients With Severe Thermal Cutaneous Injuries Receiving High-Volume Hemofiltration.

Patients with severe thermal injuries have increased metabolic demands necessitating frequent phosphate supplementation. Patients with acute renal failure may have less requirements, due to reduced elimination. However, patients being supported with renal replacement therapy have varying degree of requirements. Little published evidence depicts the incidence of hypophosphatemia and repletion requirements in patients with severe thermal injuries treated with high-volume hemofiltration (HVHF) and a high-flux membrane. The objective of this retrospective chart review was to determine the incidence of hypophosphatemia and characterize repletion requirements and response in this population. Enrolled patients had at least 20% TBSA thermal injuries and required continuous hemofiltration with prefilter replacement fluid doses ≥35 mL/kg IBW/hr. A randomly selected cohort without acute kidney injury (AKI) and matched based on age and extent of TBSA was used to compare phosphorus requirements over an initial 14-day period. Demographics, diet, and variables affecting phosphorus concentrations were collected. Sixteen patients were included in the retrospective HVHF group and 16 patients in a case-control cohort to better depict the impact of HVHF. The average age was 60.2 ± 15.1 years and median TBSA was 30% (23.4, 56.3) in the HVHF group, compared to 53.3 ± 16.4 years (P = .22) and TBSA 29% (26.4, 33.9; P = .73). All patients in the HVHF group were started on HVHF with a 1.6 m2 polyethersulfone membrane for AKI. As expected, the HVHF group exhibited statistically higher than normal baseline potassium and phosphorous laboratory values. The HVHF group experienced more days with hypophosphatemia (49.6 ± 12.4% vs 29.3 ± 16.3%, P = .012), despite 0.75 mmol/kg/day phosphorous supplementation (compared to 0.66 mmol/kg/day for the control group, P = .45). Patients with longer durations of HVHF therapy experienced increasing risk of hypophosphatemia, reaching 100% by the end of the study period. This study demonstrates severe thermally injured patients receiving HVHF for AKI are at increased risk for hypophosphatemia, and require high phosphate supplementation.

P0232 / #904: FIRST INFANT EXPERIENCE IN AMERICA HEMOPHILTED WITH CARDIO – RENAL PEDIATRIC DIALYSIS EMERGENCY MACHINE (CARPEDIEM)

Aims & Objectives: To present the first use case of CARPEDIEM in America. Methods: Case report, the examination of clinical files of infant 1.5 months, weight 3.7 Kg, with transposition of the great arteries operated, in ECMO 7 days, post-ECMO evolves with heart failure and anasarca; admitted to the pediatric intensive care unit of Roberto del Rio Hospital, Santiago, Chile. Hemofiltrates with CARPEDIEM in September 2019. Results: For 3 days continuous veno-venous hemofiltra with Carpediem machine. At the beginning, 0.15 m2 filter was used that required 2 central venous catheters (one entry and one return), plus an arterial bridge. When switching to the smallest filter (area 0.075 m2), only 1 central venous catheter 5 Fr femoral (entry and return) was required. Priming volume required between 26 to 32 ml. It was programmed with 6 ml / k / min blood flow, 25 ml / k / h prefilter replacement, 33 ml / h extraction, with 790 ml ultrafiltrate in 24 hrs. The circuit pressures were within the recommended safety range, and the filtration fraction was 11%. The filters lasted between 24 to 36 hrs. She maintained normal hemodynamics during connection, and while hemofiltration lasted. It remained normothermic. She did not present hemorrhagic, metabolic or electrolytic complications. Conclusions: Hemofiltration with CARPEDIEM proved to be safe and effective for the management of volume overload in this infant.

Revisiting Filtration Fraction as an Index of the Risk of Hemofilter Clotting in Continuous Venovenous Hemofiltration.

Hemofilter clotting is a major challenge in continuous venovenous hemofiltration (CVVH). Experts recommend keeping filtration fraction, the fraction of plasma water that is removed by ultrafiltration, below 20% or 30% to avoid clotting ([1][1]). Clotting risk is believed to markedly increase when

Dos métodos de anticoagulación en técnicas continuas de depuración extrarrenal

Introducción: Las técnicas continuas de depuración extrarrenal son la terapia de elección en pacientes críticos. Pero, no están exentas de complicaciones como la coagulación del circuito extracorpóreo. El fármaco usado tradicionalmente para la anticoagulación, es la heparina sódica. Aunque también son empleados otros métodos de anticoagulación, como el citrato. Objetivo: Evaluar la eficacia y seguridad de dos métodos de anticoagulación en pacientes tratados con terapias continuas, en unidades de cuidados intensivos del Hospital Clínic. Material y Método: Estudio observacional, retrospectivo de 54 sujetos. Se aplicaron los criterios de Insuficiencia renal aguda, descritos en el protocolo “Guía para el tratamiento sustitutivo renal en la insuficiencia renal aguda del Hospital Clínic”. Tratados mediante hemodiafiltración, combinando terapias de convección y difusión. Con fracción de filtración < 25%, y dosis de efluente de 30 ml/kg/h. 27 sujetos realizaron hemodiafiltración, reposición pre-filtro y anticoagulación con heparina sódica. El resto, hemodiafiltración, reposición post-filtro y anticoagulación con citrato. Se valoraron episodios de sangrado y duración en horas de los circuitos extracorpóreos, durante 72 horas de terapia. Resultados: El citrato demostró una mayor supervivencia de filtros (95% IC, MD 65, 44.00-72.00 vs MD 36.00, 15.00-22.00, p=0,02). Los pacientes tratados con heparina presentaron más episodios de sangrado, sin diferencias estadísticamente significativas (95% IC, n=6 vs n=9, p=0.537). Hubo un episodio de hipocalcemia en el grupo citrato, corregido según protocolo. En el grupo heparina, no se presentaron casos de trombocitopenia inducida por heparina. Conclusiones: El presente estudio, demuestra una mayor eficacia en la supervivencia de los filtros en el grupo citrato. PALABRAS CLAVE: citrato; heparina; anticoagulación regional; terapia continua depuración extrarrenal; fracaso renal agudo.

Membrane pressures predict clotting of pediatric continuous renal replacement therapy circuits

Clotting of continuous renal replacement therapy (CRRT) circuits leads to inadequate clearance, decreased ultrafiltration, and increased resource use. We identified factors associated with premature clotting of circuits during CRRT in children. In a retrospective cohort of 26 children (median age 11.8years) receiving 79 CRRT circuits (51 heparin, 22 citrate, 6 using no anticoagulation), we captured hourly pressure, flow, and fluid removal rates along with all activated clotting time (ACT) and circuit ionized calcium measurements. Cox and logistic regression models were used to examine factors associated with premature circuit clotting before the scheduled 3-day circuit change. Of the 79 circuits, 51 (64.6%) underwent unplanned filter change due to filter clotting (median duration 18.25h, interquartile range [IQR] 9.25, 33.5h), and 28 (35.4%) underwent scheduled change (median duration 66h, IQR 61.00, 69.00h). Patient age, catheter size and location, blood flow rate, and the percentage of pre-filter replacement fluid were not associated with premature clotting. Heparin circuits were less likely than citrate circuits to clot prematurely. Each 1-mmHg increase in the transmembrane or filter pressure was independently associated with a 1.5% (95% confidence interval [CI] 1.0-2.0%) and 1.5% (95% CI 1.0-2.0%) higher risk of clotting, respectively. Higher ACTs were associated with lower transmembrane (p = 0.03) and filter (p < 0.001) pressures. The majority of circuits in our cohort were subject to unplanned filter changes. Elevated transmembrane and filter pressures were associated with clotting. Our results suggest that maintaining higher ACT may decrease the risk of circuit clotting. Larger studies are needed to examine other factors that may prolong the lifespan of the CRRT circuit in this high-risk population.

Renal Replacement Therapy in Healthy Adult Horses

Renal replacement therapy (RRT) has been implemented extensively in people to facilitate recovery from acute renal failure (ARF). RRT has not been explored in horses, but might provide a further treatment option in horses with ARF. To investigate efficacy and safety of RRT in horses. Five healthy adult horses. A prospective study was performed on horses restrained in stocks and intravenously connected to a commercial RRT machine to allow continuous venovenous hemodiafiltration to be performed for 6hours. The RRT machine was set at the following flow rates: blood flow rate 250mL/min; dialysate rate 3,000mL/h; prefilter replacement pump 3,000mL/h; and postfilter replacement pump rate 2,000mL/h. Balanced electrolyte solution was used as dialysate and replacement fluid. Heart rate, respiratory rate, body temperature, direct arterial blood pressure, urine output, and various clinicopathologic parameters were measured over the study period. Renal replacement therapy was successfully performed in horses, resulting in a mean creatinine clearance of 0.127mL/kg/min (68.9mL/min) and urea reduction ratio of 24%. No adverse effects were detected although a significant decrease in rectal temperature was observed (P≤.007). A significant increase in serum phosphorus (P≤.001) and decrease in BUN (P<.001) were also noted. A significant prolongation of prothrombin (P<.01) and partial thromboplastin time (P<.0001) were observed along with a decrease in platelet count (P≤.04). Renal replacement therapy can safely and effectively be used in adult horses.

The sieving coefficient and clearance of vasopressin during continuous renal replacement therapy in critically ill children

Hypothesis As vasopressin is a small peptide, its sieving coefficient (SC) and clearance (CL) during continuous renal replacement therapy may be intermediate to those for urea and β2 microglobulin (commonly used markers for small– and middle–molecular weight solutes, respectively). Methods A prospective, minimal-risk study was undertaken of the SC and CL of vasopressin in critically ill children on the first day of continuous renal replacement therapy using AN69 membrane filters and prefilter replacement fluid. All prefilter plasma (vasopressin) samples were drawn from the arterial port after predilution. Results Nine patients with fluid overload, renal failure, or both were recruited (median age, 14 years) during the first day of either continuous venovenous hemofiltration (n = 3) or hemodiafiltration (n = 6). Multiorgan dysfunction syndrome was present in 8 patients, and 3 were in shock (2 were receiving a vasopressin infusion). Median prefilter plasma (vasopressin) was 1.7 pg/mL, although data points were skewed: 5 patients had a low prefilter plasma (vasopressin) (<2 pg/mL), and 4 patients (including 2 receiving a continuous vasopressin infusion) had a prefilter plasma (vasopressin) between 4.2 and 56.4 pg/mL. All those with low prefilter plasma (vasopressin) had an effluent (vasopressin) less than the detection limit (0.6 pg/mL). The median SC was 1 in the 4 patients with a measurable effluent (vasopressin), and their median filter CL was 48 mL/min or 39 mL/(min 1.73 m 2). Conclusions The SC and CL of vasopressin by continuous venovenous hemofiltration or hemodiafiltration in these critically ill children were similar to values for urea.

Using continuous renal replacement therapy to manage patients of shock and acute renal failure

Background:The incidence of acute renal failure (ARF) in the hospital setting is increasing. It portends excessive morbidity and mortality and a considerable burden on hospital resources. Extracorporeal therapies show promise in the management of patients with shock and ARF. It is said that the potential of such therapy goes beyond just providing renal support. The aim of our study was to analyze the clinical setting and outcomes of critically ill ARF patients managed with continuous renal replacement therapy (CRRT).Patients and Methods:Ours was a retrospective study of 50 patients treated between January 2004 and November 2005. These 50 patients were in clinical shock and had concomitant ARF. All of these patients underwent CVVHDF (continuous veno-venous hemodiafiltration) in the intensive care unit. For the purpose of this study, shock was defined as systolic BP < 100 mm Hg in spite of administration of one or more inotropic agents. SOFA (Sequential Organ Failure Assessment) score before initiation of dialysis support was recorded in all cases. CVVHDF was performed using the Diapact® (Braun) CRRT machine. The vascular access used was as follows: femoral in 32, internal jugular in 8, arteriovenous fistula (AVF) in 4, and subclavian in 6 patients. We used 0.9% or 0.45% (half-normal) saline as a prefilter replacement, with addition of 10% calcium gluconate, magnesium sulphate, sodium bicarbonate, and potassium chloride in separate units, while maintaining careful monitoring of electrolytes. Anticoagulation of the extracorporeal circuit was achieved with systemic heparin in 26 patients; frequent saline flushes were used in the other 24 patients.Results:Of the 50 patients studied, 29 were males and 21 females (1.4:1). The average age was 52.88 years (range: 20–75 years). Causes of ARF included sepsis in 24 (48%), hemodynamically mediated renal failure (HMRF) in 18 (36%), and acute over chronic kidney disease in 8 (16%) patients. The overall mortality was 74%. The average SOFA score was 14.31. The variables influencing mortality on multivariate analysis were: age [odds ratio (OR):1.65; 95% CI: 1.35 to 1.92; P = 0.04], serum creatinine (OR:1.68; 95% CI: 1.44 to 1.86; P = 0.03), and serum bicarbonate (OR: 0.76; 95% CI: 0.55 to 0.94; P = 0.01). On univariate analysis the SOFA score was found to be a useful predictor of mortality.Conclusions:Despite advances in treating critically ill patients with newer extracorporeal therapies, mortality is dismally high. Multiorgan dysfunction adversely affects outcome of CRRT. Older age, level of azotemia, and severity of metabolic acidosis are important predictors of adverse outcome.

Standard versus High-Dose CVVHDF for ICU-Related Acute Renal Failure

The effect of dosage of continuous venovenous hemodiafiltration (CVVHDF) on survival in patients with acute renal failure (ARF) is unknown. In this study, 200 critically ill patients with ARF were randomly assigned to receive CVVHDF with prefilter replacement fluid at an effluent rate of either 35 ml/kg per h (high dosage) or 20 ml/kg per h (standard dosage). The primary study outcome, survival to the earlier of either intensive care unit discharge or 30 d, was 49% in the high-dosage arm and 56% in the standard-dosage arm (odds ratio 0.75; 95% confidence interval 0.43 to 1.32; P = 0.32). Among hospital survivors, 69% of those in the high-dosage arm recovered renal function compared with 80% of those in the standard-dosage arm (P = 0.29); therefore, a difference in patient survival or renal recovery was not detected between patients receiving high-dosage or standard-dosage CVVHDF.

A Comparison of Two Citrate Anticoagulation Regimens for Continuous Veno-Venous Hemofiltration

To assess the safety and efficacy of two different commercial citrate containing pre-filter replacement fluids during continuous veno-venous hemofiltration (CVVH) in patients with frequent filter clotting. Four intensive care units. Sixty-three critically ill patients with acute renal failure (ARF). Prospective observational study. We used a commercial citrate fluid (citrate: 11 mmol/L -fluid A) as predilution replacement for CVVH. We then changed to a new commercial citrate fluid (citrate: 14 mmol/L-fluid B) as replacement fluid and performed statistical comparisons. Replacement fluid rate was fixed at 2,000 ml/hour. Filter life was 12.2 hour with fluid A compared with 17.1 hour with fluid B on average (p=0.0001). Mean post filter ionized calcium concentration was 0.52 mmol/L with fluid A compared with 0.40 mmol/L with fluid B (p<0.0001). Citrate intolerance led to cessation of treatment in one patient with fluid A and one patient with fluid B. Overall ionized calcium levels were higher (A: 1.18 vs B: 1.13 mmol/L; p<0.0001) and bicarbonate was lower (A: 22.4 vs B: 24.5 mmol/L; p<0.0001) during treatment with fluid A. Alkalemia was seen in 10 patients treated with fluid A and 16 patients treated with fluid B (NS). We have developed a simple approach to regional citrate anticoagulation for CVVH using a commercial citrate-containing fluid as replacement fluid. Increasing citrate concentration from 11 to 14 mmol/L increased filter life while maintaining relative safety and simplicity.

Commercial Low-citrate Anticoagulation Haemofiltration in High Risk Patients with Frequent Filter Clotting

This study assessed the safety and efficacy of a commercial low-citrate concentration-based pre-filter replacement fluid during continuous veno-venous haemofiltration (CVVH) in patients with frequent filter clotting and high risk of bleeding. We used a commercial low-citrate fluid as pre-dilution replacement fluid during CVVH (citrate: 11 mmol/l (33 meq/l), sodium: 140 mmol/l, chloride: 108 mmol/l and potassium: 1 mmol/l). A calcium and magnesium infusion was delivered separately by central line for the maintenance of serum ionized calcium (Cai) and total magnesium (Mg). In this prospective observational study, 30 patients, 124 filters and 1,515 treatment-hours were observed. Median filter life of citrate CVVH was 9.5 hours. Filter life in the 48 hours prior to citrate CVVH was also observed. In the patients on prior non-anticoagulant CVVH (n=14) filter life increased significantly with citrate (9.5 hours vs 5 hours; P<0.0001). In patients on prior heparin CVVH (n = 15), filter life was similar with citrate (10 hours vs 8 hours; P = 0.68). However, in patients with prior early/frequent filter clotting despite heparin (n = 11) filter life increased significantly (10 hours vs 7 hours; P=0.038). Of 411 serum Cai measurements, none showed a Cai < 0.85 mmol/l and, of 84 observations, none showed a serum Mg<0. 6 mmol/l. One patient with sepsis and shock needed to cease citrate CVVH because of progressive ionized hypocalcaemia and increasing anion gap. No other adverse effects were observed. In selected patients, CVVH with a commercial low-citrate concentration solution as pre-filter replacement fluid and a simultaneous calcium and magnesium infusion protocol appears generally safe. Filter life was acceptable and superior to that achieved with previous treatment.

Hyperosmolar solutions in continuous renal replacement therapy for hyperosmolar acute renal failure: A preliminary report*

To demonstrate the efficacy of hyperosmolar dialysis and prefilter replacement fluid solutions for continuous renal replacement therapies in the correction of hyperosmolar disorders in acute renal failure. An Institutional Review Board-approved pediatric acute renal failure database at the University of Michigan C. S. Mott Children's Hospital. Three patients were identified meeting the inclusion criteria. The mean serum sodium concentration and plasma osmolality were 158 mmol/L and 357 mOsm/kg, respectively, at the time of initiation of renal replacement therapy. The sodium and/or dextrose concentrations of the dialysate or replacement fluids initially were increased and subsequently decreased to affect the solutions' calculated osmolalities in an effort to control the rate of decline of the patients' measured plasma osmolalities. The case patients' serum sodium concentrations and plasma osmolalities were measured. Additionally, the sodium and dextrose concentrations of the dialysate or replacement fluid were recorded and the solutions' osmolalities calculated. The three patients experienced a mean rate of reduction of their serum sodium concentration and plasma osmolality of 0.5 mmol/L/hr and 1.6 mOsm/kg/hr, respectively. Hyperosmolar dialysis or prefilter replacement fluid solutions can affect a slow decline in both the serum sodium and plasma osmolality in cases of hyperosmolar acute renal failure.

Pediatric convective hemofiltration: Normocarb replacement fluid and citrate anticoagulation

Background: Continuous venovenous hemofiltration (CVVH) may be preferable over continuous venovenous hemodialysis (CVVHD) in sepsis; however, CVVH use is limited by the lack of commercially produced bicarbonate replacement solutions in the United States. Anticoagulation used for hemofiltration traditionally has been either heparin or citrate based, but to date, citrate protocols have been used predominately in CVVHD. When CVVH has been used with citrate anticoagulation, replacement solutions have had to be custom made in the pharmacy. Methods: We describe a protocol used in a series of 9 children with sepsis who underwent CVVH with the use of a commercially available bicarbonate solution (Normocarb; Dialysis Solutions Inc, Richmond Hill, Ontario, Canada) and a commercially available citrate solution (Anticoagulant Citrate Dextrose Solution Formula A [ACD-A]; Baxter Health Care, Deerfield, IL). This simplified approach to citrate anticoagulation with CVVH used Normocarb as a prefilter replacement solution under provisions of the 1997 Food and Drug Administration Modernization Act. Results: All patients had acceptable levels of solute and ultrafiltration clearance with this approach. CVVH circuit life averaged 71 hours (range, 37 to 131 hours), influenced in part by the industry recommendation to change the circuit at 72 hours, whereas no complications from this protocol were identified. Conclusion: Similar to CVVHD, this protocol is effective and simple in its components, using industry-produced solutions, avoiding the need for pharmacy-made solutions, and limiting cost and potential risk for compounding errors. Although not the purpose of this report, the patient survival rate was 55%.