This study will test whether patients who already have a permanent dialysis access (an arteriovenous fistula or graft) can safely use that access for continuous dialysis (CRRT) while they are critically ill in the intensive care unit, instead of requiring a temporary central venous catheter. About 50 patients will participate. Researchers will monitor how well the access works, whether any complications occur, and whether there are differences between fistulas and grafts. The goal is to determine whether using a patient's existing dialysis access is a safe and practical option that could reduce the need for temporary catheters and their associated risks, such as infection and bleeding.

Synopsis: This is a single-arm, single-center, pragmatic prospective study evaluating the safety and feasibility of using existing arteriovenous access (arteriovenous fistulas or arteriovenous grafts) to deliver continuous renal replacement therapy in critically ill end-stage kidney disease patients admitted to the intensive care unit. A target of 50 patients will be enrolled consecutively. The study intervention consists of CRRT delivery via AVA using standard steel hemodialysis needles (14-17 gauge) with continuous bedside monitoring by ICU nursing staff and dialysis nurse support for cannulation and decannulation. Data will be collected from the electronic health record, structured CRRT flowsheets, standardized monitoring checklists, and bedside ultrasound flow studies performed at baseline and upon CRRT discontinuation. Primary analyses will include descriptive statistics for access viability rates and complication frequencies, with exploratory subgroup analysis by access type. An independent Data Safety Monitoring Board will provide continuous safety oversight with pre-specified stopping rules.

Objectives: This study evaluates the safety and feasibility of using arteriovenous access (AVA) to deliver continuous renal replacement therapy (CRRT) in critically ill patients with end-stage kidney disease (ESKD). By utilizing existing permanent vascular access, this intervention seeks to minimize central venous catheter exposure and its associated complications. The primary aims are to investigate the technical feasibility of using AVA for the first CRRT run (Aim 1) and to evaluate the safety via serious complications associated with AVA use (Aim 2) in ESKD patients admitted to the ICU. Finally, feasibility and safety outcomes will also be summarized by access type, separately for participants with arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) (Aim 3).

Endpoints: The primary endpoint for feasibility is AVA viability for subsequent dialysis upon discontinuation of the first CRRT run, defined as functional access confirmed within 24-48 hours by the presence of thrill and/or bruit and post-CRRT flow studies showing less than 25% reduction from baseline. The primary endpoint for safety is access-related serious complications per patient, including major bleeding, access thrombosis requiring intervention, acute limb ischemia, or death related to AVA. Secondary feasibility endpoints include time on CRRT via AVA and mean blood flow rate achieved during CRRT. Secondary safety endpoints include minor access-related complications. All endpoints will additionally be summarized descriptively by access type (AVF vs. AVG) as an exploratory analysis.

Population: 50 adult patients (≥18 years), all genders, with ESKD on chronic hemodialysis for >1 year, admitted to the ICU with a functioning AVF or AVG, requiring CRRT, mechanically ventilated with an expected RASS of 0 or less. Enrollment will require agreement from both the prescribing nephrologist and the ICU physician that AVA use for CRRT is clinically appropriate and safe for the individual patient. Patients with significant coagulopathy, acute liver failure, high risk for rapid clinical deterioration, or those deemed unsuitable for AVA-based CRRT by the prescribing nephrologist or ICU attending will be excluded. Additionally, the prescribing nephrologist and ICU attending will retain the authority to discontinue the intervention at any time based on clinical judgment.

Phase: Investigator-initiated feasibility study; no investigational drug or device.

Number of Sites Enrolling Participants: 1 (ECU Health Medical Center, Greenville, NC).

Description of Study Intervention: The intervention involves the use of an existing, mature arteriovenous access (AVF or AVG) for CRRT delivery in lieu of standard non-tunneled dialysis catheter placement. AVA cannulation is performed using standard steel hemodialysis needles (14-17 gauge) by certified dialysis nurses. These needles are FDA-cleared for intermittent hemodialysis; however, their use in this protocol involves prolonged dwell times during continuous therapy, which falls outside the manufacturer's cleared labeling. As such, this application represents an off-label use of a cleared device, and systematic documentation of needle dwell duration is a component of this study. CRRT is delivered via the institutional CRRT platform (CVVH or CVVHD) at blood flow rates of 150-300 mL/min and effluent doses of 20-40 mL/kg/hour per nephrologist prescription. No investigational drugs or biologics are used.

Study Duration: Approximately 20 months (14 months enrollment plus 6 months for final follow-up completion, data cleaning, and analysis).

Participant Duration: Approximately 1 month. Active study participation spans from enrollment through CRRT discontinuation (variable, typically days), with follow-up assessments at CRRT discontinuation (ultrasound within 24-48 hours), ICU discharge or 7 days post-CRRT (whichever occurs first), and 30 days post-CRRT via chart review.

Inclusion Criteria:

1. Age ≥18 years.
2. ESKD patients on chronic hemodialysis for >1 year in duration who are admitted to the ICU and in need of CRRT.
3. Anticipated CRRT duration ≥24 hours, based on clinical assessment of the renal trajectory.
4. Patient with functioning arteriovenous access, either arteriovenous fistula or arteriovenous graft.
5. Expected mechanical ventilation for a minimum of 12 hours, based on clinical assessment of the underlying diagnosis.
6. Expected Richmond Agitation Sedation Scale (RASS) goal of 0 or less for a minimum of 12 hours, based on clinical assessment of the underlying diagnosis.
7. Patients able to tolerate placement of an arm board at the vascular access site.
8. Baseline AVA blood flow of at least 600 mL/min for AVG and 500 mL/min for AVF during ultrasonography evaluation upon enrollment.

Exclusion Criteria:

1. Age less than 18 years old.
2. Patients who receive dialysis via hemodialysis catheter or existing central catheter suitable for hemodialysis.
3. ESKD patients who, at the time of enrollment, have a sacral pressure ulcer or other clinically significant skin integrity impairment requiring frequent repositioning, extensive patient rotation, or advanced wound care management.
4. Patients with elevated INR above 5 at the time of study enrollment.
5. Patients with acute liver failure, defined as AST >1000 U/L and/or ALT >1000 U/L at the time of study enrollment.
6. Patients with a platelet count of less than 50,000 (10⁹ plt/L) at the time of study enrollment.
7. Patients with evidence of disseminated intravascular coagulation at the time of study enrollment.
8. Known pregnancy at the time of study enrollment.
9. Patients at high risk for rapid clinical deterioration, or those deemed unsuitable for AVA-based CRRT by the prescribing nephrologist or ICU physician.