Kidney Replacement Therapy for Fluid Management

The Science of Extracorporeal Ultrafiltration: Introducing a Novel Miniaturized Device

INTRODUCTION

Fluid overload has been associated with untoward outcomes in a variety of clinical settings. Isolated extracorporeal ultrafiltration (UF) allows for mechanical extraction of excess fluid and optimization of volume status without the established risks associated with use of high-dose diuretics. Conventional machines for renal replacement therapy can be used to perform isolated UF. However, they typically need high blood flow rates with high circuit volumes and the therapy has to be performed by trained nurses. Herein, we describe a novel device, the Artificial Diuresis-1, or AD 1 (Medica S.p.A., Medolla, Italy), which is a portable technology designed to perform extracorporeal UF at bedside.

MATERIALS AND METHODS

The AD 1 uses a polysulfone mini-filter to generate ultrafiltrate with the help of two forces: blood flow (Qb) and gravity (based on the height at which the ultrafiltrate collection bag is placed). In vitro experiments were performed using human blood to evaluate vascular access pressures and ultrafiltrate volumes using various central venous catheters (CVCs; 12 Fr bilume, 10 Fr with 2 separate lumens, pediatric catheter 7 Fr). A variety of combinations were tested with Qb of 20, 35, 50 mL/min and collection bag height at 20, 40, 60 cm, measuring the UF rate per minute while monitoring the pressures in the venous and arterial lines and filtration fraction.

RESULTS

The device's performance was as expected. Regarding the pediatric CVC, it was possible to perform measurements only with a Qb of 20 mL/min due to increased venous pressure. UF rates when lines were directly connected to the blood container as well as for CVC Tesio ranged from 3.7 to 11 mL/min, for the CVC Niagara™ from 4.5 to 12.5 mL/min, and for the CVC 7 Fr from 8.5 to 10 mL/min. The pressures of the vascular accesses were kept within a range of -5/-40 mm Hg for the artery and +10/+70 mm Hg for the vein. The highest venous pressure values were found with the CVC 7 Fr (+80/+100 mm Hg).

CONCLUSIONS

This novel device allows to treat patients with fluid overload in a variety of settings, from low-intensity department such as long-term care facilities to the intensive care unit. The device is small and portable, has a simple design, and is user friendly. Future studies will be needed to evaluate whether gentle UF and treatment of volume overload will translate into improvement in clinical outcomes such as a reduction in congestion-related hospital admissions.

Prediction of hemodynamic tolerance of intermittent hemodialysis in critically ill patients: a cohort study

The evaluation and management of fluid balance are key challenges when caring for critically ill patients requiring renal replacement therapy. The aim of this study was to assess the ability of clinical judgment and other variables to predict the occurrence of hypotension during intermittent hemodialysis (IHD) in critically ill patients. This was a prospective, observational, single-center study involving critically ill patients undergoing IHD. The clinical judgment of hypervolemia was determined by the managing nephrologists and critical care physicians in charge of the patients on the basis of the clinical data used to calculate the ultrafiltration volume and rate for each dialysis treatment. Seventy-nine (31.9%) patients presented with hypotension during IHD. Patients were perceived as being hypervolemic in 109 (43.9%) of the cases by nephrologists and in 107 (43.1%) by intensivists. The agreement between nephrologists and intensivists was weak (kappa = 0.561). Receiver operating characteristic curve analysis yielded an AUC of 0.81 (95% CI 0.75 to 0.84; P < 0.0001), and a cutoff value of 70 mm for the vascular pedicle width (VPW) had the highest accuracy for the prediction of the absence of hypotension. The clinical judgment of hypervolemia did not predict hypotension during IHD. The high predictive ability of the VPW may assist clinicians with critical thinking.

Multiorgan Transplant From a Donor With Solid Renal Masses: An Initial Experience and Clinical Considerations

BACKGROUND

Patients with early-stage renal cell carcinoma (RCC) are considered to be eligible donors. Although preliminary experience in using kidneys of specific pathologic types, mainly those with small renal masses (SRMs), have been established, multiorgan utilization of the same donor with SRMs is limited.

METHODS

One deceased donor whose left-side kidney was diagnosed with Fuhrman grade I RCC was included. The tumor mass in the kidney was removed through partial nephrectomy according to the gold standard. Then, 3 transplant surgeries were performed, in which 1 recipient accepted kidney transplant after tumor exeresis, 1 simultaneous heart-kidney (the contralateral one) transplant, and 1 liver transplant. Recipients were followed up according to our standard protocol for renal cancers. (All allografts were allocated in compliance with the Declaration of Helsinki and the Declaration of Istanbul.) RESULTS: After 32 months, no radiographic findings showed any morphologic changes of the lesion, and all patients were in good condition, with neither tumor recurrence nor allograft rejection or infection. No complaints such as pain, oliguria, dyspnea, nausea, or fatigue were recorded.

CONCLUSIONS

To the best of knowledge, this initial work takes the lead in elaborating the organ utilization of multiorgan donors with SRMs. We hope the experience will provide support for cross discussion concerned with multiorgan transplant from tumor-affected donors in clinical practices, further expand the donor pool and address the donor shortage problem.