We always use surgical mask for this procedure, however our goggles was changed to face shield. Is it necessary to use a mask, mind you, breathing is quite difficult!

Are you referring to accessing an AVF/AVG or a CVC? If a CVC you MUST wear a surgical mask to prevent exhaling germs onto the access site. In the case of an AVF/AVG the face shield alone is sufficient, but if you want to wear a mask too that's ok. The idea is to protect yourself from blood splatters. Henry schein makes a combination eye shield and surgical mask. They are disposables, HS#104-7321 and come 25/box