Fluid Resuscitation in a Model of Uncontrolled Hemorrhage: Too Much Too Early, or Too Little Too Late?

Abstract

Early fluid resuscitation in hypotensive trauma patients is controversial due to the risk of increasing blood loss and mortality. We determined the effects of infusion rate and time of resuscitation on blood loss and mortality and compared the outcome to nonresuscitated animals in severe, uncontrolled hemorrhagic shock in a rat model. In anesthetized rats, piercing of the infrarenal aorta with a 25-G needle caused a fall of mean arterial pressure to <20 mm Hg and blood loss of about 20 ml/kg in 90% of the animals. Animals were assigned to the following treatment groups (n= 6): 60 ml/kg of lactated Ringer's solution (LR) infused at a rate of 1.5 ml/min and given at 2.5 min (Group I), 5 min (Group II), or 10 min (Group III) postinjury, or LR infused at a rate of 3.0 ml/min and given at 5 min (Group IV) or 10 min (Group V) postinjury. Another group (n= 9) was not resuscitated. The animals were followed for 3 hr. Total blood loss in Group I (30.5 ± 2.6 ml/kg) was significantly (P< 0.05) higher when compared to nonresuscitated animals (22.1 ± 0.8 ml/kg) or Group III (22.7 ± 1.0 ml/kg), and also significantly higher in Group IV (35.8 ± 4.1 ml/kg) when compared to nonresuscitated animals or Group V (23.0 ± 1.2 ml/kg). The mortality rate was 7/9 in nonresuscitated animals and 5/6 in Group IV; both were significantly higher than in Groups II, III, and V (0 or 1/6) and markedly higher than in Group I (2/6). Conclusions: In this model of uncontrolled hemorrhage, initially uncorrected severe shock resulted in a high mortality rate. The risk of increased blood loss and mortality associated with early fluid resuscitation could be diminished by avoiding too fast of infusion rates early after the injury.