Changing of capacity during the sprint

Hello everybody, I am the Scrum Master of a small team of 4 dev (including me) + P.O.

My question is: how to deal with a change of capacity during the current sprint?

E.g.: if something unexpected come up for a team member and he has to leave for 3/4 days (the sprint length is 2 weeks), what is the best thing to do? Would it be correct to set-up a meeting to review the scope of the sprint?

And what if the changing of capacity is small, like 1 or 2 days ? Maybe a provisioning of 1 day for each team member shall be counted when planning capacity?

Thank you,