Continuous venovenous hemofiltration improves cardiac performance by mechanisms other than tumor necrosis factor-alpha attenuation during endotoxic shock.

Abstract

To assess the effects of continuous venovenous hemofiltration (CWH) on global and regional hemodynamics, plasma lactate, and tumor necrosis factor-oa (TNF-a) levels during endotoxic shock in dogs. Thirty pentobarbital-anesthetized and mechanically ventilated dogs were divided into six groups of five dogs each. Group 1 served as a control, undergoing CWH at 3 Uhr without endotoxin. Group 2 served as the endotoxin-alone time-matching group. Group 3 received CWH 1 hr after endotoxin at 3 Uhr for 270 mins. Group 4 received CWH 1 hr after endotoxin at 3 Uhr for 150 mins and at 6 Uhr for an additional 120 mins. Group 5 and group 6 received the ultrafiltrate from group 1 and group 3, respectively. Three hours after endotoxin challenge, dogs treated with CWH at 3 Uhr had a higher cardiac output (4.9 + 0.6 vs. 2.9 + 0.6 Umin; p < .05) and stroke volume (35 + 7 vs. 20 + 4 mL; p < .05) and a lower pulmonary vascular resistance (116 26 vs. 331 + 126 dyne-sec/cm5; p < .05) than the endotoxin-alone group. Five hours after endotoxin, dogs treated with CWH at 6 Uhr also had higher hepatic (464 + 164 vs. 126 + 75 mUmin; p < .05) and femoral (95 + 46 vs. 30 + 34 mL/min; p < .05) blood flow. Moreover, dogs treated with CWH at 6 Uhr had higher mean arterial blood pressure (84 + 24 vs. 40 + 15 mm Hg; p < .05) and left ventricular stroke work index (1.1 + 0.6 vs. 0.2 + 0.2 g/kg; p < .05) than the endotoxin-alone group. Plasma lactate levels were lower in the CWH group at 6 Uhr (2.7 + 1.1 mmol/L) than in the endotoxin-alone group (4.4 + 0.6 mmol/L; p < .05). Plasma TNF-ao levels were unaffected, and only minor amounts of TNF-o were found in the ultrafiltrate. In this acute endotoxic shock model, CWH at 3 Uhr improved cardiac performance and decreased pulmonary vasoconstriction. Moreover, CWH at 6 LUhr also increased arterial blood pressure and left ventricular stroke work, increased hepatic and femoral arterial blood flow, and decreased blood lactate levels. These effects were not attributable to TNF-alpha removal.