occlusion is the blockage or closing of a blood vessel or hollow...

occlusion is
the blockage or closing of a blood vessel or hollow organ.

the control devices are the devices that are not the unilife device
Control Device: FDA-cleared syringe driver with FDA-cleared infusion set, 4) Control Device: FDA-cleared syringe driver attached to investigational device. Three milliliters of saline were infused through the four devices over 3 minutes.