Reduction of Oxygen-Carrying Capacity Weakens the Effects of Increased Plasma Viscosity on Cardiac Performance in Anesthetized Hemodilution Model

We investigated the effects of reduced oxygen-carrying capacity on cardiac function during acute hemodilution, while the plasma viscosity was increased in anesthetized animals. Two levels of oxygen-carrying capacity were created by 1-step and 2-step hemodilution in male golden Syrian hamsters. In the 1-step hemodilution (1-HD), 40% of the animals' blood volume (BV) was exchanged with 6% dextran 70 kDa (Dx70) or dextran 2000 kDa (Dx2M). In the 2-step hemodilution (2-HD), 25% of the animals' BV was exchanged with Dx70 followed by 40% BV exchanged with Dx70 or Dx2M after 30 minutes of first hemodilution. Oxygen delivery in the 2-HD group consequently decreased by 17% and 38% compared to that in the 1-HD group hemodiluted with Dx70 and Dx2M, respectively. End-systolic pressure and maximum rate of pressure change in the 2-HD group significantly lowered compared with that in the 1-HD group for both Dx70 and Dx2M. Cardiac output in the 2-HD group hemodiluted with Dx2M was significantly higher compared with that hemodiluted with Dx70. In conclusion, increasing plasma viscosity associated with lowering oxygen-carrying capacity should be considerably balanced to maintain the cardiac performance, especially in the state of anesthesia.