The effects of
Dextran 70 with NaCl as against
Ringer's acetate on hemodynamics, gas exchange,
oxygen transport and survival were evaluated in a porcine model of pulmonary and circulatory insufficiency induced by a continuous i.v.
endotoxin infusion over 6 h.
Dextran and
Ringer's acetate were infused continuously to maintain baseline mean left atrial pressure (MLAP) throughout the
endotoxin period. Twelve pigs receiving
endotoxin +
Ringer's acetate displayed a progressive 45% decline in cardiac output (Qt) and a two peaked increase in pulmonary vascular resistance (PVR) with a late increase of 250%. Venous admixture (Qva/Qt) increased progressively more than 6-fold and extravascular lung water (EVLW) increased by 55%. Mean arterial blood pressure (MAP) fell by 25%,
oxygen delivery by 40%, base excess (BE) ranged between - 4.5 and - 9 mmol.1(-1) at the end of the
endotoxin period and 4 of 12 animals died. Polymorphonuclear cell count (PMNs) fell rapidly by 90% and was severely decreased throughout the
endotoxin period. Contrastingly, the 12 pigs that received
endotoxin +
Dextran maintained Qt near baseline and PVR was significantly lower in this group. Qva/Qt increased progressively more than 4-fold, but was significantly lower than in the Ringer's group as was the increase in EVLW (23%). MAP only decreased by 10%,
oxygen delivery only decreased by 20%. BE ranged between - 1.0 and - 3.0 at the end of the
endotoxin period and all animals survived. PMNs fell by 90% at 0.5 h but subsequently tended to return towards baseline. PMNs were significantly increased compared with the Ringer's group. The amount of
Ringer's acetate necessary to maintain a stable MLAP averaged 4.6 times the
Dextran volume. The superiority of
Dextran as compared with
Ringer's acetate in this endotoxemic
shock model seems to be consequent to better rheological effects combined with pharmacological interactions with granulocytes.