[Continuous hemofiltration: an extrarenal filtration method used in intensive care]

Area of Science:

• Nephrology and Critical Care Medicine
• Renal Replacement Therapy
• Extracorporeal Blood Purification

Context:

• Continuous haemofiltration (CHF) is a renal replacement therapy that mimics physiological glomerular filtration.
• It is used in intensive care settings for patients with acute renal failure and fluid/electrolyte imbalances.
• Various techniques exist, including continuous arteriovenous haemofiltration (CAVH) and continuous venovenous haemofiltration (CVVH), with or without diffusive transport.

Purpose:

• To describe the principles, techniques, and clinical applications of continuous haemofiltration.
• To highlight the management of fluid balance, electrolyte disturbances, and acid-base balance using CHF.
• To discuss challenges such as anticoagulation, drug clearance, and infection risk associated with CHF.

Summary:

• CHF filters water and small solutes (up to 6,000 d) from blood, requiring replacement with electrolyte solutions.
• CAVH uses arterial pressure for blood flow, while CVVH requires a blood pump; diffusive transport can enhance toxin clearance.
• Effective fluid management allows for standard intravenous feeding in acute renal failure patients; careful anticoagulation and drug selection are crucial.

Impact:

• CHF can fully replace renal function, producing significant ultrafiltrate volume daily.
• Early initiation of CHF is recommended for acute renal failure, especially with elevated blood urea levels.
• Consideration of potential complications like bleeding, hypothermia, and bacterial contamination is essential for optimal patient management.