The Senegalese striker has been struck down with a bout of flu and has not been able to get out of bed to join his teammates for the Round of 16 first leg.
"Papiss has been sick since Sunday, so myself and the doctor went to see him this morning to see whether we felt he could travel, with me definitely thinking he could," said Pardew.
"But he didn't look well, to be honest, so we have had to leave him behind, unfortunately. That's one of the reasons I brought Shola, because I didn't have any intention of bringing Shola.
"It's a surface that he's been advised in the past not really to play on, so it leaves me a little bit short of striking options."