We have a 225 bed Women's (10%) and Children's (90%) hospital nearby. Our experience is the oxygen consumption is similar (or greater) than a regular hospital. Our biggest problem is the medical air system. It's frequently undersized on the pumps and pipe size causing lag pump alarms and significant pressure drops.
If the Med Air pipe sizing is the same as the Oxygen pipe sizing, you're much better off.
Don't come up short and anticipate what the consumption will be in 30-50 years from now. You don't customers paying for the same thing a second time later on.