A pulsatile pump the output of which is infinitely variable between a slow pulsatile flow and increased up to a sharply pulsed flow rate until the pulses run together and a smooth flow results, and which may be varied between wide output pressure and frequency limits. The pump is comprised of a pneumatic control circuit, at least two pneumatically isolated compression chambers, and a novel inlet/outlet pump cartridge and condition-responsive locking means. Operation of the pump is controlled by the use of novel tactile pneumatic response switches. Each compression chamber is communicated with a supply of working fluid through the cartridge. Means are provided for varying the operation of the pneumatic circuit and hence the pump. A flow of pressurized fluid, such as air or nitrogen, is used as the operating media of the pneumatic circuit, although other fluids may be used. Means for monitoring and adjusting pump system parameters are also provided. The pump operates entirely through the use of pneumatic energy, avoiding the use of electricity.