A medical pump includes first and second compartments, which are configured to accept respective first and second containers of fluid to be pumped to a medical device, and a paddle, which is fitted between the first and second compartments. The pump additionally includes a control module, which is configured to drive the paddle to alternate between first time periods in which the paddle applies pressure to the first container so as to pump the fluid therefrom, and second time periods in which the paddle applies the pressure to the second container so as to pump the fluid therefrom.
