# 🩺 Renal Replacement Therapy in AKI

**🏅 KDIGO 2026 draft AKI/AKD Guideline — Chapter 5: Renal Replacement Therapy**

## ⏱️ RRT Initiation — Deferred Strategy

**Rec 5.1.1 (1C):** We suggest a **deferred timing strategy** for RRT initiation over an early/pre-emptive strategy in critically ill adults with AKI.

This recommendation is grounded in three landmark trials demonstrating no benefit (and potential harm) from early RRT initiation:

**STARRT-AKI (2020)**

N=2,927. No mortality benefit with accelerated vs. standard strategy. More adverse events with early RRT.

**AKIKI (2016)**

N=620. Delayed strategy: 49% of patients never needed RRT. No mortality difference.

**IDEAL-ICU (2018)**

N=488. Early RRT in septic shock: no mortality benefit. Stopped early for futility.

**PP 5.1.1:** Shared decision-making with patients and families regarding RRT initiation, goals, and potential outcomes should be incorporated into clinical practice. **PP 5.1.2:** For patients with a high probability of needing RRT, plan BEFORE absolute indications are met — including transfer to centers with nephrology services if needed.

### 🚨 Indications for RRT Initiation (Deferred Strategy)

#### 🔴 Absolute Indications

- **Refractory fluid overload**
- **Refractory hyperkalemia**
- **Severe metabolic acidosis** (refractory to medical therapy)
- **Uremic complications** — encephalopathy, pericarditis, bleeding

#### ⚠️ Special Situations

- Consider CRRT for **hepatic encephalopathy ≥grade 2** with hyperammonemia even without conventional AKI indications
- **Time-limited trial of RRT** can be started if uremic/metabolic complications are plausibly confounding neurological evaluation (PP 5.1.5)

## 🔄 RRT Modality Selection

| Feature | CRRT | IRRT (IHD) | PIRRT (SLED) | Acute PD |
|----|----|----|----|----|
| Hemodynamic Stability | Best | Worst | Good | Good |
| Solute Clearance | Continuous | Intermittent high | Intermediate | Lower |
| Preferred For | Unstable, brain injury, liver failure | Stable patients | Alternative to CRRT | Resource-limited, select peds |
| Anticoagulation | Citrate preferred | UFH / LMWH | UFH / LMWH | None |

### 📋 Key Modality Recommendations

**Rec 5.2.1 (2C):** We suggest CRRT or acute PD over conventional IRRT for **hemodynamically unstable** patients. **PP 5.2.2:** CRRT is preferred in patients with **acute brain injury or increased ICP** (avoids rapid osmotic shifts). **PP 5.2.4:** Prolonged intermittent RRT (**PIRRT / SLED**) is an acceptable alternative to CRRT where resources or expertise favor it. **PP 5.2.5:** Transition from CRRT → IRRT when the patient is **hemodynamically stable** and ICP risks have resolved.

## 💉 RRT Dose-Intensity

#### CRRT Dose (Rec 5.3.1, 1B)

20–25 mL/kg/h

Effluent volume target

Use ideal or adjusted body weight for BMI ≥30

#### IRRT / PIRRT Dose (Rec 5.3.1, 1B)

Kt/V 3.9/week

Minimum delivered dose target

Review adequacy before each IRRT session

#### Acute Peritoneal Dialysis

Kt/V 2.2/week

18–24 L PD fluid per day

Review adequacy daily for CRRT, before each IRRT session

### 🚫 AGAINST High-Volume Hemofiltration (HVHF) in Sepsis (Rec 5.3.2, 1B)

KDIGO 2026 draft **recommends against** high-volume hemofiltration (\>35–45 mL/kg/h) in sepsis and septic shock.

**Rationale:**

- HVHF was proposed to remove inflammatory cytokines in sepsis
- Evidence does NOT support a mortality benefit

**Key Trials:**

- **IVOIRE trial:** No survival benefit with HVHF vs. standard dose
- **ATN trial:** Intensive dose (35 mL/kg/h) = standard dose (20 mL/kg/h)
- **RENAL trial:** Higher intensity CRRT did not reduce mortality

**Harms of HVHF:**

- Increased electrolyte losses (hypokalemia, hypophosphatemia)
- Enhanced antibiotic clearance → subtherapeutic levels
- Greater nursing workload and cost

**Bottom Line:** Standard dose (20–25 mL/kg/h) is the evidence-based target. More is NOT better.

## 🩸 Vascular Access for RRT

#### 📋 Catheter Management

- Use **standardized care bundles** for catheter insertion and maintenance
- **No routine or scheduled catheter changes**
- Replace poorly performing catheters via **new venipuncture** or **guidewire exchange** (individualize decision)

#### 🔌 AV Fistula / Graft Use

- Existing AV fistulas and grafts are **suitable for IRRT**
- **AVOID using AV access for CRRT** — dislodgement risk with continuous use

#### 🔄 Tunneled Catheter Transition

- Transition to **tunneled dialysis catheter** if low probability of AKI resolution
- Also consider when preparing for **discharge with ongoing RRT need**

## 💊 Anticoagulation for RRT

**Rec 5.5.1 (1B):** We recommend **regional citrate anticoagulation** over heparin for CRRT in patients without contraindications to citrate.

#### 🧪 Regional Citrate (Preferred for CRRT)

- Chelates calcium in the circuit → prevents clotting
- Calcium infused separately to patient
- Longer circuit life vs. heparin
- Lower bleeding risk
- **Also preferred in HIT** (PP 5.5.5)

#### 💉 Alternatives When Citrate Contraindicated

- **Unfractionated heparin (UFH)**
- **Epoprostenol** (prostacyclin)
- **Nafamostat** (serine protease inhibitor)

**PP 5.5.2:** Regional citrate + systemic anticoagulation may be combined for hypercoagulable states

#### 🩸 Heparin-Induced Thrombocytopenia (HIT)

- **Argatroban** (direct thrombin inhibitor)
- **Danaparoid**
- **Bivalirudin**
- **Regional citrate** also preferred in HIT (PP 5.5.5)

**IHD / PIRRT Anticoagulation:** UFH or LMWH are standard for patients without increased bleeding risk. Regional citrate is not typically used for intermittent modalities.

## 🧫 Hemofilters & Solutions

#### 🧬 Membrane Selection

- Use **biocompatible membranes**
- Synthetic membranes (polysulfone, polyethersulfone) preferred

#### ⏳ Maximize Circuit Life (Non-Pharmacologic)

- Optimal **catheter tip position** — right atrium
- Use **predilution** mode when possible
- Prefer **CVVHD or CVVHDF** over CVVH (convection-only modes clot faster)

#### 🧪 Solution Specifications

- **Bicarbonate buffer** (not lactate) in shock, liver failure, lactic acidemia
- Use **sterile CRRT solutions**
- Use **AAMI-compliant solutions** for IRRT

## ✅ RRT Discontinuation

Discontinue RRT when kidney function is adequate for clinical needs, or per patient/family preference aligned with goals of care.

#### 📊 Predictors of Successful Discontinuation

\>450 mL/24h UOP without diuretics \>2300 mL/24h UOP with diuretics ≥23 mL/min 2-hour timed creatinine clearance

#### 💊 Diuretics Around Discontinuation

- Diuretics may **augment urine output**
- However, diuretics are **NOT proven to facilitate AKI resolution**
- Use for volume management, not to "kick-start" kidneys

**Clinical Pearl:** A rising urine output trend — especially if sustained for 24–48 hours — is more meaningful than any single measurement.

### 🎯 Key Learning Points — RRT in AKI

#### ⏱️ Timing

- Deferred strategy preferred (STARRT-AKI, AKIKI, IDEAL-ICU)
- Initiate for refractory complications, not arbitrary thresholds
- Plan ahead if RRT likely needed
- Shared decision-making essential

#### 🔄 Modality

- CRRT for hemodynamic instability, brain injury, liver failure
- PIRRT is acceptable alternative to CRRT
- Transition CRRT → IRRT when stable
- PD for resource-limited settings

#### 💉 Dose & Anticoagulation

- CRRT: 20–25 mL/kg/h (standard, not high-volume)
- HVHF does NOT improve outcomes in sepsis
- Regional citrate preferred for CRRT
- Bicarbonate buffer in shock and liver failure

#### ✅ Discontinuation

- UOP \>450 mL/24h (no diuretics) predicts success
- 2h CrCl ≥23 mL/min also predictive
- Diuretics augment UOP but don't resolve AKI
- Tunneled catheter if prolonged need expected

## 📚 Sources

1.  **STARRT-AKI Investigators; Bagshaw SM, Wald R, Adhikari NKJ, et al.** Timing of Initiation of Renal-Replacement Therapy in Acute Kidney Injury. *N Engl J Med.* 2020;383(3):240-251. [PMID: 32668114](https://pubmed.ncbi.nlm.nih.gov/32668114/). *— Accelerated vs standard KRT initiation; no mortality benefit, more dialysis dependence with accelerated.*
2.  **Gaudry S, Hajage D, Schortgen F, et al; AKIKI Study Group.** Initiation Strategies for Renal-Replacement Therapy in the Intensive Care Unit. *N Engl J Med.* 2016;375(2):122-133. [PMID: 27181456](https://pubmed.ncbi.nlm.nih.gov/27181456/). *— Early vs delayed RRT in ICU AKI; no difference in mortality.*
3.  **Barbar SD, Clere-Jehl R, Bourredjem A, et al; IDEAL-ICU Trial Investigators.** Timing of Renal-Replacement Therapy in Patients with Acute Kidney Injury and Sepsis. *N Engl J Med.* 2018;379(15):1431-1442. [PMID: 30304656](https://pubmed.ncbi.nlm.nih.gov/30304656/). *— Early vs delayed RRT in septic AKI; no mortality benefit; trial stopped early for futility.*
4.  **RENAL Replacement Therapy Study Investigators; Bellomo R, Cass A, Cole L, et al.** Intensity of continuous renal-replacement therapy in critically ill patients. *N Engl J Med.* 2009;361(17):1627-1638. [PMID: 19846848](https://pubmed.ncbi.nlm.nih.gov/19846848/). *— RENAL trial — high-intensity (40 mL/kg/hr) vs standard (25 mL/kg/hr) CRRT; no difference in mortality.*
5.  **VA/NIH Acute Renal Failure Trial Network; Palevsky PM, Zhang JH, O'Connor TZ, et al.** Intensity of renal support in critically ill patients with acute kidney injury (ATN). *N Engl J Med.* 2008;359(1):7-20. [PMID: 18492867](https://pubmed.ncbi.nlm.nih.gov/18492867/). *— ATN trial — intensive vs less-intensive RRT; no mortality benefit.*
6.  Kidney Disease: Improving Global Outcomes (KDIGO) Acute Kidney Injury Work Group. KDIGO Clinical Practice Guideline for Acute Kidney Injury. Kidney Int Suppl. 2012;2:1–138. [Official KDIGO guideline](https://kdigo.org/wp-content/uploads/2016/10/KDIGO-2012-AKI-Guideline-English.pdf).

📚 For Educational Purposes Only — KDIGO 2026 draft AKI/AKD Guideline Recommendations

© 2025 Andrew Bland MD - All Rights Reserved

### Also on this topic

The same subject at other levels of depth.

- **Primer chapter:** [Chapter 25: Dialysis & Renal Replacement Therapy](https://urinenephrology.org/nephrology-textbook/chapters/chapter-22-dialysis.html)


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