A cassette holder includes an actuator assembly and a cassette plate. The actuator assembly includes an actuator (e.g., a valve actuator or a sensing actuator) and a shaft, with the shaft including a head, a base, and a perimeter groove defined between the head and the base. The cassette plate includes an opening aligned with the actuator and a keyhole at least partially aligned with the shaft. The keyhole is associated with a channel of the cassette plate, which is configured to receive at least a portion of a lever. The lever is movable between a locked position (in which the lever is primarily positioned within the channel) preventing removal of the shaft from the keyhole and an unlocked position (in which the lever is primarily positioned outside of the channel) allowing for removal of the shaft from the keyhole.
