A gas inflation/evacuation system and sealing system for use with occlusive devices in vascular procedures. The gas inflation/evacuation system is removably connectable via the sealing system to a proximal portion of a guidewire assembly having a guidewire that defines a lumen and includes a first syringe system for evacuating the lumen and a second syringe system for introducing a biocompatible gas into the lumen to inflate an occlusive balloon that is in fluid communication with the lumen a plurality of times. The sealing system selectively seals the proximal portion of the guidewire and includes a crimping mechanism and a compression sealing mechanism having a resilient seal for sealing around the proximal portion of the guidewire when it is passed therethrough.