Kean's side are bottom of the league table and he made five changes for the 2-0 loss in south Wales and also elected not to risk the defensive trio of Christopher Samba, Martin Olsson and Michel Salgado, who have all had hamstring injuries.
The Scot said: "Before the game I had a decision to make in as far as I wanted to push Samba, Olsson and Salgado, who never travelled for this game. They could have played at a push and if we had been in a slightly different position in the league."
He added: "We have Swansea coming up so I made five changes and left those lads behind. We wanted to make sure we have those lads available for Saturday. Saturday has to kick-start our season. We are in a position where we have forfeited going through in this competition and having the chance to reach a cup final.
"We now have games against sides who are within touching distance of us in the league and we need to treat those games as cup finals because we have not got through to the final of this competition."
Prior to the game a tribute was paid to Wales manager Gary Speed who died on Sunday when the stadium united in a round of applause in recognition of his career before a minute's silence. Both managers and Football Association of Wales chief executive Jonathan Ford also laid floral tributes on a Welsh flag, and during the game there were chants of "there's only one Gary Speed".
And Cardiff manager Malky Mackay said the result was a fitting tribute.
"I am very proud of the group, and proud of everyone at the football club," he said. "It was an emotional evening for everyone at the club and everyone in Wales.
"We knew that going out tonight we would have a big attendance and it was a very moving tribute to Gary.
"We wanted to get through just as that little tribute to him to get Wales into the semi-finals of the Carling Cup."
Source: PA
Source: PA