The Gunners have injury problems in defence after William Gallas aggravated a calf problem in last week's 2-2 draw at home in the first leg.
Alex Song had been pencilled in to start the return at Camp Nou on Tuesday night, but picked up a groin injury against Wolves at the weekend in addition to carrying a knee complaint.
Veteran defender Campbell is the likeliest option to partner Thomas Vermaelen against the holders, but Wenger is concerned about the 35-year-old being able to play back-to-back matches.
Mikael Silvestre is the other contender to slot into central defence against Barcelona and Wenger will make a late decision regarding his team.
"Ideally I wanted Song available, but he is not, so the decision is between Sol Campbell and Silvestre," said Wenger.
"The disadvantage of Sol is that it is his second game in four days, while the disadvantage with Silvestre and Vermaelen is that it is two left-footed players.
"I will make the decision, but Sol is experienced enough to tell me if he is fit enough or not. I trust him completely to be responsible.
"He is not on an ego trip, and does not want to let the team down.
"At some stage, if he feels fit to play, then I will make the decision about who starts the game.
"However, we have to focus on the team performance - if we do not win the ball and give Barcelona the ball at the Nou Camp, then no matter who plays centre-back, he will have problems."