Abstract
We studied the relative efficacy of two plasma substitute therapies in a canine model for hemorrhagic shock. Anesthetized dogs were bled to maintain a mean arterial pressure (mAP) at 50 mmHg and then administered a single bolus injection of 6 % hydroxyethyl starch (HES) with a molecular weight of 70 kDa (HES70 group) or 200 kDa (HES200 group) at a volume equivalent to the blood withdrawn. The efficacy of both therapies in maintaining the hemodynamic variables, the plasma colloidal and crystalloidal osmotic pressures (Pcop and Posm), and the circulating blood volume (CBV) were investigated. CBV was measured by the pulse-dye densitometry (PDD) method. After resuscitation, hemodynamic variables were better maintained in the HES200 group than in the HES70 group. Particularly, mAP, mean pulmonary arterial pressure, pulmonary arterial wedge pressure, cardiac index, left ventricular stroke work index, and maximum rate of left ventricular pressure change, were maintained at a satisfactorily stable level in the HES200 group as compared with the HES70 group. Moreover, Pcop and CBV in the HES200 group were significantly greater than those in the HES70 group. On the other hand, Posm did not differ between the two groups. HES200 may be a more effective volume replacement therapy than HES70 for induced hemorrhagic shock because of improvement and maintenance of hemodynamic variables, CBV and Pcop.
