Smaller circuits for smaller patients: improving renal support therapy with Aquadex™

Pediatric continuous renal replacement therapy: have practice changes changed outcomes? A large single-center ten-year retrospective evaluation

Background

To evaluate changes in population characteristics and outcomes in a large single-center pediatric patient cohort treated with continuous renal replacement therapy (CRRT) over a 10 year course, coincident with multiple institutional practice changes in CRRT delivery.

Methods

A retrospective cohort study with comparative analysis of all patients treated from 2004 to 2013 with CRRT in the neonatal, pediatric, and cardiovascular intensive care units within a free-standing pediatric tertiary care hospital.

Results

Three hundred eleven total patients were identified, 38 of whom received concurrent treatment with extracorporeal membrane oxygenation. 273 patients received CRRT only and were compared in two study eras (2004–2008 n = 129; 2009–2013 n = 144). Across eras, mean patient age decreased (9.2 vs 7.7 years, p = 0.08), and the most common principal diagnosis changed from cardiac to liver disease. There was an increase in patients treated with continuous renal replacement therapy between cohorts for acute kidney injury of multi factorial etiology (44% vs 56%) and a decrease in treated patients with sepsis (21% vs 11%, p = 0.04). There was no significant difference in survival to hospital discharge between eras (47% vs 49%). Improvement in outpatient follow-up after discharge amongst survivors was seen between study eras (33% vs 54%).

Conclusions

Despite multiple institutional practice changes in provision of CRRT, few changes were seen regarding patient demographics, diseases treated, indications for therapy, and survival over 10 years at a single tertiary care. Recognition of need for follow-up nephrology care following CRRT is improving. Ongoing assessment of the patient population in a changing landscape of care for critically ill pediatric patients remains important.

Treatment of AKI in developing and developed countries: An international survey of pediatric dialysis modalities

HYPOTHESIS

Acute kidney injury (AKI) is a common cause of morbidity and mortality worldwide, with a pediatric incidence ranging from 19.3% to 24.1%. Treatment of pediatric AKI is a source of debate in varying geographical regions. Currently CRRT is the treatment for pediatric AKI, but limitations due to cost and accessibility force use of adult equipment and other therapeutic options such as peritoneal dialysis (PD) and hemodialysis (HD). It was hypothesized that more cost-effective measures would likely be used in developing countries due to lesser resource availability.

METHODS

A 26-question internet-based survey was distributed to 650 pediatric Nephrologists. There was a response rate of 34.3% (223 responses). The survey was distributed via pedneph and pcrrt email servers, inquiring about demographics, technology, resources, pediatric-specific supplies, and preference in renal replacement therapy (RRT) in pediatric AKI. The main method of analysis was to compare responses about treatments between nephrologists in developed countries and nephrologists in developing countries using difference-of-proportions tests.

RESULTS

PD was available in all centers surveyed, while HD was available in 85.1% and 54.1% (p = 0.00), CRRT was available in 60% and 33.3% (p = 0.001), and SLED was available in 20% and 25% (p = 0.45) centers of developed and developing world respectively. In developing countries, 68.5% (p = 0.000) of physicians preferred PD to costlier therapies, while in developed countries it was found that physicians favored HD (72%, p = 0.00) or CRRT (24%, p = 0.041) in infants.

CONCLUSIONS

Lack of availability of resources, trained physicians and funds often preclude standards of care in developing countries, and there is much development needed in terms of meeting higher global standards for treating pediatric AKI patients. PD remains the main modality of choice for treatment of AKI in infants in developing world.

Acute kidney injury in the fetus and neonate

Acute kidney injury (AKI) is an under-recognized morbidity of neonates; the incidence remains unclear due to the absence of a unified definition of AKI in this population and because previous studies have varied greatly in screening for AKI with serum creatinine and urine output assessments. Premature infants may be born with less than half of the nephrons compared with term neonates, predisposing them to chronic kidney disease (CKD) early on in life and as they age. AKI can also lead to CKD, and premature infants with AKI may be at very high risk for long-term kidney problems. AKI in neonates is often multifactorial and may result from prenatal, perinatal, or postnatal insults as well as any combination thereof. This review focuses on the causes of AKI, the importance of early detection, the management of AKI in neonates, and long-term sequela of AKI in neonates.

Neonatal extracorporeal renal replacement therapy-a routine renal support modality?

Peritoneal dialysis (PD) is generally considered the preferred extracorporeal therapy for neonates with acute kidney injury (AKI). However, there are situations when PD is not suitable, such as in patients with previous abdominal surgery, hyperammonemia and significant ascites or anasarca. Additionally, with a need to start PD soon after catheter placement, there is increased risk of PD catheter leak and infection. Extracorporeal continuous renal replacement therapy (CRRT) is challenging in severely ill neonates as it requires obtaining adequately sized central venous access to accommodate adequate blood flow rates and also adaptation of a CRRT machine meant for older children and adults. In addition, ultrafiltration often cannot be set in sufficiently small increments to be suitable for neonates. Although CRRT practices can be modified to fit the needs of infants and neonates, there is a need for a device designed specifically for this population. Until that becomes available, providing the highest level of care for neonates with AKI is dependent on the shared experiences of members of the pediatric nephrology community.

The management of neonatal acute and chronic renal failure: A review

Most babies with chronic renal failure are identified antenatally, and over half that are treated with peritoneal dialysis receive kidney transplants before school age. Most infants that develop acute renal failure have hypotension following cardiac surgery, or multiple organ failure. Sometimes the falls in glomerular filtration and urine output are physiological and reversible, and sometimes due to kidney injury, but (illogically) it is now common to define them all as having 'acute kidney injury'. Contrary to widespread opinion, careful interpretation of the plasma creatinine concentrations can provide sensitive evidence of early acute renal failure. Conservative management frequently leads to under-nutrition or fluid overload. Acute peritoneal dialysis is often technically fraught in very small patients, and haemotherapies have been limited by vascular access and anticoagulation requirements, the need to blood-prime circuits, and serious limitations in regulating fluid removal. Newer devices, including the Nidus, have been specifically designed to reduce these difficulties.

CVVHD treatment with CARPEDIEM: small solute clearance at different blood and dialysate flows with three different surface area filter configurations

BACKGROUND

The CARdiorenal PEDIatric EMergency (CARPEDIEM) machine was originally designed to perform only continuous venovenous hemofiltration (CVVH) in neonatal and pediatric patients. In some cases, adequate convective clearance may not be reached because of a limited blood flow. In such conditions, the application of diffusive clearance [continuous venovenous hemodialysis (CVVHD)] would help optimize blood purification. In this study, the CARPEDIEM™ machine was modified to enable the circulation of dialysis through the filter allowing testing of the performance of CARPEDIEM™ machine in CVVHD.

METHODS

Three different polyethersulfone hemodialyzers (surface area = 0.1 m(2), 0.2 m(2), and 0.35 m(2), respectively) were tested in vitro with a scheduled combination of plasma flow rates (Qp = 10-20-30 ml/min) and dialysis fluid flow rate (Qd = 5-10-15 ml/min). Three sessions were performed in co-current and one in counter-current configuration (as control) for each filter size. Clearance was measured from the blood and dialysate sides and results with mass balance error greater than 5 % were discarded.

RESULTS

Urea and creatinine clearances for each plasma/dialysate combination are reported: clearance increase progressively for every filter proportionally to plasma flow rates. Similarly, clearances increase progressively with dialysate flow rates at a given plasma flow. The clearance curve tends to present a steep increase for small increases in plasma flow in the range below 10 ml/min, while the curve tends to plateau for values averaging 30 ml/min. As expected, the plateau is reached earlier with the smaller filter showing the effect of membrane surface-area limitation. At every plasma flow, the effect of dialysate flow increase is evident and well defined, showing that saturation of effluent was not achieved completely in any of the experimental conditions explored. No differences (p > 0.05 for all values) were obtained in experiments using whole blood instead of plasma or using co-current versus counter-current dialysate flow configuration.

CONCLUSIONS

Although plasma flow and filter surface give an important contribution to the level of clearance urea and creatinine, it appears evident that dialysate flow plays an essential role in the blood purification process, justifying the use of CVVHD versus CVVH in case of high dialysis dose requirement and/or limited blood flow rate.

Novel Use of an Ultrafiltration Device as an Alternative Method for Fluid Removal in Critically Ill Pediatric Patients with Cardiac Disease: A Case Series

Fluid overload (FO) is a common complication for pediatric patients in the intensive care unit. When conventional therapy fails, hemodialysis or peritoneal dialysis is classically used for fluid removal. Unfortunately, these therapies are often associated with cardiovascular or respiratory instability. Ultrafiltration, using devices such as the Aquadex™ system (Baxter Healthcare, Deerfield, IL, USA), is an effective tool for fluid removal in adult patients with congestive heart failure. As compared to hemodialysis, ultrafiltration can be performed using smaller catheters, and the extracorporeal volume and minimal blood flow rates are lower. In addition, there is no associated abdominal distension as is seen in peritoneal dialysis. Consequently, ultrafiltration may be better tolerated in critically ill pediatric patients. We present three cases of challenging pediatric patients with FO in the setting of congenital heart disease in whom ultrafiltration using the Aquadex™ system was successfully utilized for fluid removal while cardiorespiratory stability was maintained.

Use of an Amnioport to Maintain Amniotic Fluid Volume in Fetuses with Oligohydramnios Secondary to Lower Urinary Tract Obstruction or Fetal Renal Anomalies

OBJECTIVE

We describe a technique to maintain amniotic fluid in fetuses with severe oligo-/anhydramnios secondary to lower urinary tract obstruction or fetal renal disease when urine production is inadequate to maintain a normal amniotic fluid volume (AFV).

METHODS

An amnioport was inserted into the amniotic space. The catheter was secured to prevent dislodgment and tunneled to a subcutaneous reservoir. The reservoir was accessed as necessary, infusing normal saline to maintain AFV. Pregnancy continued until term or indicated delivery.

RESULTS

Since 2010, 15 patients in this category were considered for an amnioport. Six chose comfort care and one elected percutaneous amnioinfusions. Nine amnioport procedures were performed in eight patients. There were no fetal deaths. All eight had successful restoration and maintenance of amniotic fluid. Delivery ranged from 9 to 96 days after placement (mean 63.7 days). One died due to unrecognized laryngeal web and another one died of pulmonary hypoplasia after preterm premature rupture of membranes. None of the remaining six had pulmonary hypoplasia. Three remain alive.

DISCUSSION

Severe oligo-/anhydramnios in the second trimester secondary to fetal anomalies is almost uniformly lethal due to pulmonary hypoplasia without restoration of amniotic fluid. The amnioport procedure may allow pulmonary survival but commits families to postnatal care decisions regarding pulmonary and renal complications.