The key to the generation of flashbacks in the venous system of the pediatric simulator:
The simulator will only generate blood return when there is sufficient pressure in the venous system. The magnitude of the pressure depends on the placement of the reservoir bag. When the pressure is small, we have two ways to solve it.
Solution A: Fill approx 450 ml or more liquid to the reservoir, make reservoir inflate to create enough pressure, or anyway you can give pressure to the reservoir, like putting weighty stuff on it. Enough pressure could help flashback effect come out readily.