CVVH

CVVH stands for continuous veno-venous hemofiltration, a modality of continuous renal replacement therapy (CRRT) used to treat acute kidney injury and fluid or solute overload in critically ill patients who cannot tolerate intermittent hemodialysis. The treatment runs continuously, typically over 24 hours, in an intensive care setting.

CVVH relies on convective solute transport. Blood from a central venous catheter passes through a hemofilter; plasma water and dissolved solutes are filtered across the membrane as ultrafiltrate. Replacement fluid is infused into the circuit to maintain fluid balance and solute concentrations. The prescribed ultrafiltration rate determines the amount of fluid and solutes removed.

A CRRT machine with a hemofilter and circuit is used, usually via veno-venous access. Anticoagulation is common, using systemic heparin or regional citrate. Replacement fluid composition is adjusted for electrolytes and acid-base status. Therapy can be delivered pre-filter, post-filter, or in a combined approach to optimize stability and filter life.

Indications include acute kidney injury with oliguria or anuria, fluid overload unresponsive to diuretics, and toxin removal when rapid clearance is needed or the patient is hemodynamically unstable. Contraindications include active major bleeding, severe coagulopathy, or circumstances that make CRRT impractical.

Compared with other CRRT modalities, CVVH emphasizes convective clearance, while CVVHD relies on diffusion and CVVHDF combines both. Convective methods are effective for middle-molecular solutes, whereas diffusion favors small solutes. Choice depends on patient status and available resources.

Possible complications include hypotension, electrolyte disturbances, acid-base shifts, bleeding with anticoagulation, and circuit clotting. Ongoing monitoring of hemodynamics, labs, filter life, and anticoagulation is required.