CRRT (Continuous Renal Replacement Therapy) is a dialysis technique used in intensive care for patients with acute kidney injury. It offers slow, continuous removal of waste and fluids, maintaining hemodynamic stability and supporting critical care management
Introduction
Continuous Renal Replacement Therapy (CRRT) is a cornerstone in the management of critically ill patients with acute kidney injury (AKI), particularly when conventional intermittent haemodialysis is not feasible. CRRT allows for the gradual and continuous removal of solutes and fluid, minimising haemodynamic instability.
Definition of CRRT
CRRT encompasses a group of blood purification therapies performed over 24 hours or more, providing continuous support to patients with renal failure, especially in intensive care settings. Unlike intermittent haemodialysis, CRRT offers slower solute and fluid removal, reducing the risk of complications in haemodynamically unstable patients.
Indications for CRRT
- Acute kidney injury (AKI) with haemodynamic instability
- Severe fluid overload unresponsive to diuretics
- Electrolyte imbalances (e.g., hyperkalaemia, hypercalcaemia)
- Severe metabolic acidosis
- Sepsis with multi-organ dysfunction
- Drug or toxin overdose requiring extracorporeal removal
Purpose of CRRT
- To maintain fluid, electrolyte, and acid-base balance in critically ill patients
- To support renal function until recovery or transition to another modality
- To prevent or manage complications associated with renal failure
Overview of CRRT Modalities
Types of CRRT
- Continuous Venovenous Haemofiltration (CVVH): Removes solute by convection.
- Continuous Venovenous Haemodialysis (CVVHD): Removes solute by diffusion.
- Continuous Venovenous Haemodiafiltration (CVVHDF): Combines convection and diffusion.
- Slow Continuous Ultrafiltration (SCUF): Primarily for fluid removal.
Mechanisms of Action
- Diffusion: Movement of solutes from an area of higher to lower concentration across a semipermeable membrane (as in CVVHD).
- Convection: Solutes are dragged along with water removal across the membrane (as in CVVH and CVVHDF).
- Ultrafiltration: Removal of plasma water through a pressure gradient (as in SCUF).
Indications for Each Modality
- CVVH: Useful for patients with significant fluid overload and solute removal needs.
- CVVHD: Preferred when solute clearance is the priority.
- CVVHDF: Ideal for patients requiring both fluid and solute removal.
- SCUF: Selected when fluid removal is the sole requirement.
Pre-procedure Preparation
Patient Assessment
- Review patient history and indication for CRRT.
- Assess vital signs, mental status, and fluid balance.
- Evaluate laboratory results: renal function tests, electrolytes, clotting profile.
- Inspect vascular access sites for infection or patency.
Equipment Preparation
- CRRT machine (ensure functionality and calibration)
- Sterile CRRT circuit and filter
- Appropriate dialysate and replacement fluids
- Anticoagulation agents as prescribed (e.g., heparin, citrate)
- Personal protective equipment (PPE)
- Emergency resuscitation equipment at bedside
Consent
- Obtain informed consent from patient or next of kin as per institutional policy.
- Explain the procedure, its purpose, potential risks, and benefits in clear, simple terms.
- Address patient or family concerns and answer questions.
Procedure for CRRT
| S.No | Nursing Action | Rationale |
| 1 | Review physician’s order and patient’s clinical status | Ensures appropriateness of CRRT modality and settings for the patient’s current needs |
| 2 | Perform hand hygiene and use PPE | Prevents nosocomial infections and protects healthcare workers |
| 3 | Confirm patient identity using two identifiers | Reduces risk of patient misidentification and associated errors |
| 4 | Inspect and prepare vascular access (e.g., central line) | Maintains access patency, prevents infection, and ensures therapy effectiveness |
| 5 | Prime CRRT circuit and filter | Removes air and contaminants; prevents air embolism and infection |
| 6 | Connect patient to CRRT circuit using aseptic technique | Reduces risk of catheter-related infections |
| 6 | Initiate CRRT as per prescribed parameters | Delivers therapy tailored to patient’s clinical requirements |
| 7 | Monitor vital signs (BP, HR, RR, SpO₂, temperature) at least hourly | Detects early signs of haemodynamic instability or complications |
| 8 | Assess fluid input/output and daily weights | Guides fluid management and assesses therapy effectiveness |
| 9 | Monitor laboratory values (electrolytes, urea, creatinine, ABG, coagulation) | Identifies metabolic imbalances and therapy adequacy |
| 10 | Check CRRT circuit for alarms, pressure changes, and filter clotting | Ensures uninterrupted therapy and early identification of technical problems |
| 11 | Assess vascular access for infection, bleeding, or dislodgement | Prevents access-related complications |
| 12 | Administer anticoagulation as prescribed and monitor for bleeding | Prevents circuit clotting while minimising bleeding risk |
| 13 | Provide skin care and frequent position changes | Prevents pressure ulcers and maintains skin integrity |
| 14 | Educate patient and family about CRRT and signs of complications | Promotes cooperation, reduces anxiety, and supports early identification of problems |
| 15 | Document all assessments, interventions, and patient responses | Ensures continuity of care and legal compliance |
Monitoring and Ongoing Care
- Vital Signs: Monitor blood pressure, heart rate, respiratory rate, oxygen saturation, and temperature at least hourly. Sudden changes may indicate complications such as hypotension, sepsis, or bleeding.
- Fluid Balance: Record input and output meticulously, including all intravenous fluids, oral intake, urine output, and ultrafiltration volumes. Daily weights provide an additional measure of fluid status.
- Electrolyte Monitoring: Check serum electrolytes (potassium, sodium, calcium, magnesium, phosphate) regularly. Adjust replacement fluids and therapy parameters as needed.
- Laboratory Assessment: Monitor urea, creatinine, arterial blood gases, and coagulation profile per protocol.
- CRRT Circuit Surveillance: Inspect for alarms, pressure changes, filter clotting, and blood leaks. Respond promptly to any issues.
- Vascular Access Assessment: Check for signs of infection (redness, swelling, discharge), bleeding, or dislodgement at the catheter site.
- Anticoagulation: Administer and monitor anticoagulants as per prescription. Watch for signs of bleeding or clotting.
- Skin and Pressure Area Care: Provide regular skin assessment and repositioning to prevent pressure ulcers.
- Pain and Comfort Measures: Assess for discomfort and provide analgesia or comfort interventions as needed.
Special Considerations
- Infection Control: Stringent aseptic technique is critical during all procedures related to CRRT, especially vascular access care. Use of PPE and proper hand hygiene must be emphasised.
- Vascular Access Maintenance: Central venous catheters are the most common access for CRRT. Secure the catheter properly, inspect frequently, and avoid unnecessary handling to minimise infection and dislodgement risks.
- Patient Comfort and Dignity: Provide privacy, explain all procedures, and address pain or anxiety promptly. Maintain warmth and comfort during the therapy.
- Haemodynamic Instability: Be vigilant for hypotension, arrhythmias, or signs of shock. Adjust therapy settings and notify the physician promptly if instability occurs.
- Psychosocial Support: Offer emotional support to the patient and family. Involve them in care decisions and provide clear, culturally sensitive communication.
- Drug Dosing Adjustments: Many medications are cleared by CRRT. Collaborate with the medical team for appropriate dose adjustments to avoid toxicity or subtherapeutic effects.
- Transport and Mobility: Plan for safe transport if required. Ensure CRRT circuit and vascular access are secure during movement.
- Nutritional Support: Collaborate with dietitians to provide adequate nutrition, as patients on CRRT may have increased protein and caloric needs.
Patient and Family Education
- Explain the purpose and process of CRRT using simple, non-technical language.
- Discuss possible sensations (e.g., coldness, discomfort at access site) and what to expect during therapy.
- Highlight the importance of reporting symptoms such as chills, fever, bleeding, or pain.
- Provide written materials and reinforce verbal teaching, considering language and literacy levels.
- Encourage family involvement in care and decision-making, respecting cultural values and preferences.
- Clarify the need for ongoing monitoring and potential duration of therapy.
Documentation
- Record all baseline and ongoing assessment findings, including vital signs, laboratory values, and fluid balance data.
- Document all interventions, changes in therapy settings, and patient responses.
- Note any complications, alarms, or technical issues with the CRRT machine and actions taken.
- Include patient and family education provided and their understanding of information shared.
- Report significant findings promptly to the medical team and record all communications.
REFERENCES
- Annamma Jacob, Rekha, Jhadav Sonali Tarachand: Clinical Nursing Procedures: The Art of Nursing Practice, 5th Edition, March 2023, Jaypee Publishers, ISBN-13: 978-9356961845 ISBN-10: 9356961840
- Omayalachi CON, Manual of Nursing Procedures and Practice, Vol 1, 3 Edition 2023, Published by Wolters Kluwer’s, ISBN: 978-9393553294
- Sandra Nettina, Lippincott Manual of Nursing Practice, 11th Edition, January 2019, Published by Wolters Kluwers, ISBN-13:978-9388313285
- Adrianne Dill Linton, Medical-Surgical Nursing, 8th Edition, 2023, Elsevier Publications, ISBN: 978-0323826716
- Donna Ignatavicius, Medical-Surgical Nursing: Concepts for Clinical Judgment and Collaborative Care, 11th Edition ,2024, Elsevier Publications, ISBN: 978-0323878265
- Lewis’s Medical-Surgical Nursing, 12th Edition,2024, Elsevier Publications, ISBN: 978-0323789615
- AACN Essentials of Critical Care Nursing, 5th Ed. Sarah. Delgado, 2023, Published by American Association of Critical-Care Nurses ISBN: 978-1264269884
- Ernstmeyer K, Christman E, editors. Nursing Fundamentals [Internet]. 2nd edition. Eau Claire (WI): Chippewa Valley Technical College; 2024. PART IV, NURSING PROCESS. Available from: https://www.ncbi.nlm.nih.gov/books/NBK610818/
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