Slow blood flow rates in CAVH caused hemofilter clotting, and the waste and water removal was variable.
One key advantage of the CVVH system is the ability to provide higher, consistent blood flow rates, usually greater than 150 mL/min using a blood pump, compared to CAVH. The use of a blood pump to provide higher blood flow rates increased the ultrafiltrate volumes that could be attained in CAVH (see Table 2).
CAVH CVVH Blood flow dependent on blood Blood flow rates set on pump pressure Slow blood flow Ability to adjust blood flow rates Less efficient water removal, More efficient water removal, less solute clearance and better solute clearance Frequent clotting Brisk blood flow decreases clotting No alarm system Arterial, venous, and air pressure alarms Risk using femoral artery No femoral artery used, large veins only CAVH = continuous arteriovenous hemofiltration CVVH = continuous venovenous hemofiltration