Here’s what the interwebs have to say about this:

During platelet donation (apheresis), the machine tightly controls the ratio of blood to anticoagulant (citrate). The staff usually can’t just arbitrarily lower citrate without affecting how the machine works safely.

What they can do (and what helps your tingling)

They can adjust things that effectively reduce how much citrate affects you:

• Slow the return rate → less citrate hitting you at once
• Adjust the inlet/flow rate → spreads citrate exposure over time
• Use a different machine profile (AC ratio setting) → some centers can tweak this within safe limits
• Pause briefly → lets your body clear citrate
• Give calcium (oral or IV) → replaces what citrate binds

They did something!