Effect of continuous arteriovenous hemofiltration combined with systemic vasopressor therapy on depressed left ventricular contractility and tissue oxygen delivery in canine Escherichia coli sepsis

Abstract

Background: In a previous study, we showed that continuous arteriovenous hemofiltration (CAVH) reversed the depression in left ventricular (LV) contractility in canine Escherichia coli sepsis by the removal of a circulating substance the molecular weight of which is less than 30,000. Despite the normalization of LV contractility, however, we were unable to demonstrate an improvement in systemic arterial blood pressure (BP), presumably because the mechanisms underlying the depression in LV contractility and the decrease in BP are different in sepsis. In the current study, we examined the effect of combined treatment with CAVH and the α- adrenergic agonist phenylephrine on LV mechanics and tissue oxygen delivery in our canine E. coli model. Methods: Measurements were obtained at baseline (condition B), after 4 h of sepsis (condition S), and after 2 h of CAVH and phenylephrine (condition P) (total of 6 h of sepsis). During P, phenylephrine was infused to restore BP to that found at baseline. The slope of the end- systolic pressure-dimension relation was used as the index of LV contractility; LV anterior-posterior dimensions were measured by sonomicrometry. Results: During combined CAVH and phenylephrine treatment, the decrease in the slope of the end-systolic pressure-dimension relation otherwise observed at S was reversed. The slope (mean ± SD) was 57.5 ± 32 mmHg/mm at B versus 22.2 ± 8 mmHg/mm at S (P < 0.05, B vs. S) versus 62 ± 37 mmHg at P (P < 0.05 S vs. P) (analysis of variance). Mean BP was restored to that found at B (123 ± 19 mmHg versus 82 ± 14 mmHg (P< 0.05 B vs. S) versus 116 ± 27 mmHg (P< 0.05 S vs. P). Combination treatment with CAVH and phenylephrine also improved stroke volume (39.3 ± 13.5 versus 32 ± 8 versus 44 ± 12 ml) and tissue oxygen delivery during P compared with results obtained when phenylephrine was given alone. Conclusions: Our study offers a rationale for the combined use of phenylephrine and CAVH in the reversal of cardiac depression and hypotension in sepsis.