A surgical system having a cassette with an aspirant collection chamber and an aspiration exhaust line that drains into the aspirant collection chamber. A fluid line containing a valve allowing fluid from the irrigation fluid container to be vented into the aspirant collection chamber. A source of pressurized air is connected to the irrigation fluid container and is used to pressurize the fluid container. When the pressure within the fluid container needs to be increased, pressurized air from the pressurized air source is allowed to enter the fluid container. When the pressure within the fluid container needs to be decreased, irrigation fluid is allowed to be bled out of the fluid container and enter the collection chamber. In this manner, a direct fluidic connection with the gas contained within the fluid container does not need to be maintained.
