Responsiveness to different volume therapies following hemodilution and hemorrhagic shock: a comparative experimental study in rats

Abstract

Guidelines for volume replacement for acutely hemorrhaged and hemodiluted trauma patients have not been well established. To evaluate the effects of acute hemodilution on mean arterial pressure (MAP), and responsiveness of acutely hemodiluted and subsequently hemorrhaged rats to different volume therapies. 180 rats were hemodiluted to simulate hemorrhaged trauma patients with persistent bleeding after high volume replacement with isotonic solutions. Thirty hemodiluted [Anemia (ANE) group] animals received no further treatment. The remaining 150 animals were subjected to hypovolemic shock and randomized into five groups, according to the treatment option employed: Control (CTL) animals did not receive subsequent treatment after hemorrhagic hypovolemia, SAL4 animals received isotonic saline 4 mL/kg, SAL32 animals received isotonic saline 32 mL/kg, HS animals received hypertonic saline 4 mL/kg and BLD animals received re-infusion of drawn blood. Highest mean arterial pressure (MAP) was achieved by BLD, followed by SAL32 and HS. MAP after treatment of BLD, HS, SAL32 and ANE were higher than CTL (p=0.036). At 85 and 95 minutes of experiment, SAL4, SAL32 and HS presented the lowest hematocrit levels (p<0.01). At day 3, ANE, CTL and HS had the highest hematocrit. SAL4 and CTL groups presented the highest mortality rates. Hypertonic saline is an effective and safe initial therapy for hemodiluted rats undergoing hemorrhagic shock, with an overall outcome comparable to blood replacement or high volume isotonic saline administration.