Early but not delayed continuous arteriovenous hemofiltration improves cardiovascular function in sepsis in dogs

Continuous arteriovenous hemofiltration (CAVH) has been advocated as treatment to remove inflammatory mediators and thereby to improve hemodynamic parameters in sepsis. However, the results obtained with CAVH have been inconsistent. In a canine model of bacteremic Pseudomonas aeruginosa pneumonia, we tested the hypothesis that the time course of the institution of CAVH may be important in obtaining a beneficial treatment effect.

Two protocols were performed in phenobarbital-anesthetized dogs. In the early hemofiltration study (EHS), CAVH for 3 h was initiated 2 h post-pneumonia before mean arterial pressure (MAP) fell. In the late hemofiltration study (LHS), CAVH for 3 h was initiated at 5 h post-pneumonia when a decrease in MAP had already occurred. Hemodynamic measurements included cardiac output (CO), stroke volume (SV), and stroke work (SW). Myocardial depressant activity [filterable cardiodepressant substance (FCS)] found in plasma was assessed by bioassay at each measurement interval.

In EHS, after 5 h of sepsis, SW, CO, and SV in the hemofiltered pneumonia group were higher as compared with the nonhemofiltered pneumonia group. In contrast, in LHS, no differences in hemodynamic parameters were found between the two pneumonia groups. In both EHS and LHS, plasma FCS activity was decreased to similar extents by CAVH.

These results suggest the time course of institution of CAVH may be important in obtaining a beneficial treatment effect in sepsis.