Resuscitation fluids for the treatment of hemorrhagic shock in dogs: effects on myocardial blood flow and oxygen transport

Abstract

Background and methods: The efficacy of using colloids vs. crystalloids in the treatment of hemorrhagic shock remains controversial. An important aspect in the treatment of hemorrhagic shock is the reestablishment of normal myocardial blood flow after fluid resuscitation. This study, therefore, was designed to investigate the effect of resuscitation with different plasma substitutes on myocardial blood flow and oxygen transport after acute hemorrhage in dogs. Forty-three dogs were anesthetized and bled into a heparinized Wiggers' reservoir to a mean arterial pressure of 35 mm Hg. The animals were maintained at this level of hypotension for 90 mins, whereupon the animals were infused with one of five randomly selected fluids: a) succinylated gelatin (Gelofusine); b) urea-linked gelatin (Haemaccel); c) 6% hetastarch (Hespan); d) lactated Ringer's solution; or e) shed blood. Myocardial blood flow was measured using the radiolabeled microsphere technique.

Results: Resuscitation with succinylated gelatin, urea-linked gelatin, and hetastarch resulted in significant hemodilution. However, infusion of these fluids resulted in a compensatory hyperemia that increased myocardial blood flow and maintained oxygen transport at preshock values. No hyperemia was observed with reinfusion of shed blood. Resuscitation with lactated Ringer's solution produced significant hemodilution without hyperemia and, consequently, a significant decrease in oxygen transport.

Conclusions: These results suggest that in lieu of blood, the artificial colloids are more effective than crystalloids in restoring myocardial blood flow and oxygen transport after acute experimental hemorrhage in dogs.