The purpose of this protocol is to evaluate the safety of a selective cytopheretic device (SCD) in patients that are on continuous renal replacement therapy (CRRT) for acute renal failure (ARF).

Acute renal failure is a condition where the kidneys are not capable of producing adequate urine. Therefore, another way to remove waste from the body is needed to hopefully allow time for the kidneys to heal. One method of removing waste from the body is called Continuous Renal Replacement Therapy (CRRT) or variations of that therapy. This study will evaluate the safety of the device while it is connected to the CRRT tubing for up to 7 days. Patients will be followed up until day 60 following the treatment.

Inclusion Criteria:

1. A patient, or legal representative, has signed a written informed consent form.
2. Must be receiving medical care in an intensive care unit (e.g., ICU, MICU, SICU, CTICU, Trauma, Mixed, other).
3. Age 18 to 80 years.
4. Females of child bearing potential who are not pregnant (confirmed by a negative serum pregnancy test) and not lactating if recently post-partum.
5. Must be receiving and tolerating CRRT therapy for a minimum of 4 hours, but not longer than 24 hours.
6. Expected to remain in the ICU for at least 96 hours after evaluation for enrollment.
7. A clinical diagnosis of ATN due to hemodynamic or toxic etiologies. ATN is defined as acute renal failure occurring in a setting of acute ischemic or nephrotoxic injury with oliguria (average <20 mL/hr) for >6-12 hours or: an increase in serum creatinine ≥2 mg/dL (≥1.5 mg/dL in females) over a period of ≤4 days. (Note: Prerenal, hepatorenal, vascular, interstitial, glomerular, and obstructive etiologies are excluded on clinical or other diagnostic grounds.)
8. At least one non-renal organ failure (modified SOFA organ system score >2), as defined in Appendix A or presence (proven or suspected) of sepsis as defined in Appendix B.
9. All patients must be able to tolerate regional citrate anticoagulation.

Exclusion Criteria:

1. Contraindications to regional citrate anticoagulation.
2. Irreversible brain damage based on available historical and clinical information.
3. Presence of a renal transplant at any time.
4. Non-candidacy for acute renal replacement therapy.
5. Non-renal organ transplantation within six months of screening date.
6. Presence of preexisting chronic renal failure prior to this episode of ARF. Preexisting chronic renal failure is defined as baseline serum creatinine >2.5 mg/dL (men), or >2.0 mg/dL (women).
7. ARF occurring in the setting of burns, obstructive uropathy, allergic interstitial nephritis, acute or rapidly progressive glomerulonephritis, vasculitis, hemolytic-uremic syndrome, thrombotic thrombocytopenic purpura (TTP), malignant hypertension, scleroderma renal crisis, atheroembolism, functional or surgical nephrectomy, hepatorenal syndrome, cyclosporine or tacrolimus nephrotoxicity.
8. Metastatic malignancy which is actively being treated or may be treated by chemotherapy or radiation during the subsequent three month period after study therapy
9. Chronic immunosuppression (e.g., AIDS, chronic glucocorticoid therapy >20 mg/day prednisone equivalent on a chronic basis, or chemotherapy). The acute use of glucocorticoids is permissible
10. Severe liver failure as documented by a Child-Pugh Liver Failure Score >12.
11. Do Not Resuscitate (DNR) status.
12. Comfort measures only.
13. Patient is moribund or for whom full supportive care is not indicated.
14. Patient not expected to survive 28 days because of an irreversible medical condition.
15. Any medical condition that the Investigator thinks may interfere with the study objectives.
16. Physician refusal.
17. Patient pregnant.
18. Patient is a prisoner.
19. Pre-morbid weight >128.5 kg.
20. More than one hemodialysis treatment or longer than 24 hours since starting CRRT.
21. Platelet count <30,000/mm3.
22. Concurrent enrollment in another interventional clinical trial. Patients enrolled in clinical trials where only measurements and or samples are taken (NO TEST DEVICE OR DRUG USED) are allowed to participate.
23. Use of any other Investigational drug or device within the previous 30 days.