"Splanched" is a portmanteau word combining "spent" and "blanched". To say that someone is "splanched out" is to say he looks like he's been through the ringer; that he's pale, drawn, slightly unwell; like he's just undergone a draining personal ordeal; like he's just seen a ghost.
"Wow, have you seen Calvin? He just got back from Japan where he was searching the bins for old vinyl copies of LibbyTitus' second album and he looks totally splanched out.