Physiologic effects of colloidal (5%
albumin, 6% hydroxyethylstarch, 6%
dextran-70) and crystalloidal (
Ringer's lactate) fluids were examined in rats (six in each fluid group) after infusion of an LD99 of
rattlesnake venom, previously shown to produce
shock secondary to increased vascular permeability.
Venom infusion (iv, 2.0 mg/kg, 30 min) was followed by fluid infusion (iv, 30 min) in quantities sufficient to reverse
venom-induced hemoconcentration.
Venom infusion decreased mean arterial pressure, increased blood
lactate, and increased hematocrit in all animals (p less than .01). Fluid infusion reversed these changes, although six times the volume of
crystalloid was required to produce
hemodilution comparable to the colloidal fluids (120 ml/kg
Ringer's lactate, 20 ml/kg
colloids). Although no significant changes in the respiratory parameters were noted after administration of the three
colloids,
Ringer's lactate produced decreases in PaC2 (107 +/- 6 torr, mean +/- SEM to 72 +/- 7, p less than .05), increases in PaCO2 (30 +/- 4 torr to 55 +/- 5, P less than .001), decreases in plasma
colloid osmotic pressure (14.2 +/- 0.8 torr to 6.6 +/- 0.9, p less than .001) at the end of fluid infusion. These changes were associated with significantly increased wet-dry lung ratios (p less than .001) in identically prepared animals, sacrificed after fluid infusion. In spite of the development of
pulmonary edema in the
crystalloid-treated animals, survival was similar for each group (6/6 for
albumin and
dextran, 5/6 for hydroxyethylstarch and
Ringer's lactate). We thus conclude that both colloidal and crystalloidal fluid
resuscitation leads to survival in permeability
shock.
Resuscitation with crystalloidal fluid, however, requires significantly greater volumes and is associated with the development of
pulmonary edema.