Comparison of polyacrylonitrile (AN69) and polysulphone membrane during hemofiltration in canine endotoxic shock

This study was designed to compare the effects of continuous venovenous hemofiltration (CVVH) with two different membranes, polysulphone and polyacrylonitrile (AN69), on global and regional hemodynamics, plasma lactate, tumor necrosis factor-alpha levels, and plasma nitrite/nitrate during endotoxic shock in dogs.

Fifteen pentobarbital anesthetized and mechanically ventilated dogs were randomized into three groups of five dogs each. One group served as an endotoxin alone, time matching group and, 1 hr after endotoxin administration, the two other groups received CVVH at 3 L/hr for 270 mins, with either a polysulphone membrane or an polyacrylonitrile membrane.

At 90 mins after endotoxin administration, dogs receiving CVVH with polyacrylonitrile membranes had a higher cardiac output, stroke volume, and left-ventricular stroke work index than the endotoxin alone and the polysulphone groups. CVVH with either polyacrylonitrile or polysulphone membranes prevented the rise in pulmonary artery pressure and pulmonary vascular resistance compared with the endotoxin alone group. Plasma lactate levels were not significantly altered, but the fall in bicarbonate seen in the endotoxin alone group did not occur in the two CVVH groups. Tumor necrosis factor levels in the plasma were not significantly altered by CVVH and remained very low (<50 pg/mL) in the ultrafiltrate fluid.

In this acute endotoxic shock model, CVVH with the polyacrylonitrile membrane improved cardiac performance when compared with the polysulphone membrane. These effects could be caused by a more effective adsorption of inflammatory mediators other than tumor necrosis factor. Whether the polyacrylonitrile membrane should be preferred over the polysulphone membrane for CVVH in severe sepsis warrants further experimental and clinical study.