T. Ayuse et al., ALTERATIONS IN LIVER HEMODYNAMICS IN AN INTACT PORCINE MODEL OF ENDOTOXIN-SHOCK, American journal of physiology. Heart and circulatory physiology, 37(3), 1995, pp. 1106-1114
Septic shock decreases preload, increases splanchnic blood pooling and
edema formation, and induces hepatic dysfunction. We hypothesized tha
t the hemodynamic effects of endotoxemic shock on the portal venous (P
V) and hepatic arterial (HA) vascular beds contribute to this picture.
Multipoint pressure-flow relationships were generated to evaluate the
slope (resistance or conductance) and effective back pressure (P-back
) in each bed in an intact porcine model of endotoxemia. Slope and P-b
ack were determined during endotoxemia over 300 min (n = 8) and compar
ed with sham-treated control studies (n = 5). At time (t) = 60 min, HA
slope significantly decreased (P < 0.05) without a change in P-back.
The HA buffer response (HABR), defined as a decrease in HA resistance
produced by reduction in PV flow (Q(pv)), was abolished at t = 90 min.
The PV P-back significantly increased without a change in PV slope. A
t t = 300 min, HA slope returned to baseline, and the HABR was present
while PV slope and P-back increased (P < 0.05). Fractional flow (flow
relative to cardiac output) was constant except for a transient incre
ase in HA fractional flow at t = 60 min. Histological studies showed f
ocal necrosis and hemorrhage without evidence of vasoconstriction or t
hrombosis. In conclusion, endotoxic shock leads to time-dependent impa
irment of Q(pv) with increased PV resistance, causing an increase in s
planchnic blood pooling and subsequent decrease in venous return. The
HA bed is dilated early with an absent HABR. Later an HABR is present
but defined by increased HA resistance for a given Q(pv). These altera
tions in hemodynamic homeostasis help to account for the specific invo
lvement of the splanchnic bed in septic shock, the high incidence of l
iver dysfunction, and, if generalized to other organ beds, the roles o
f arterial and venous compartments in sepsis.