Cardiopulmonary and splanchnic blood flow during 48 hours of a continuous infusion of endotoxin in conscious rigs: A model of hyperdynamic shock

Hyperdynamic shock can be modeled in pigs by chronic administration of a co ntinuous, low-dose infusion of endotoxin. Lipopolysaccharide (LPS, E. coli 0111:B4, 80 ng/kg/min i.v.) initially resulted in a hypodynamic shock state with significant decreases in mean arterial pressure (112 +/- 3 mmHg at ba seline to 94 +/- 4 mmHg at 8 h) and cardiac index (5.35 +/- 0.32 L/min/m(2) at baseline to 4.07 +/- 0.32 L/min/m(2) at 4 h). Eight hours after the ini tiation of the LPS infusion, cardiac index rose to above baseline values (5 .82 +/- 0.4 L/min/m(2) at 8 h) and remained elevated for the duration of th e 48-h study (6.54 +/- 0.39 L/min/m(2) at 48 h). Similarly, systemic vascul ar resistance fell significantly by 8 h (1640 +/- 100 dyne sec cm(-5) at ba seline to 1239 +/- 80 dyne sec cm(-5) at 8 h) and remained decreased for th e duration of the study. Blood flow in major abdominal vessels, including t he left renal artery, the cranial mesenteric artery, and the portal vein, p aralleled changes in the cardiac index. Serum concentrations of tumor necro sis factor were increased after 2 h of LPS infusion, but did not remain ele vated above baseline concentrations for more than about 4 h despite continu ous LPS challenge. Concentrations of tumor necrosis factor did not differ b etween arterial and portal Venous samples. This model of hyperdynamic shock should be useful to assess potential therapies for septic shock.