Left-handed reliever Glendon Rusch was diagnosed with a blood clot on his right lung. He is out for the rest of the season, and it's unknown if his career is in jeopardy.
"We're not concerned about his career right now," Cubs manager Dusty Baker said. "We're concerned about his life."
"It's scary and really puts things in perspective," Cubs closer Ryan Dempster said.
It's been a frustrating year for Rusch, who enjoyed two banner seasons as a starter and reliever for the Cubs in 2004 and 2005. But this year, he was 3-8 with a 7.46 ERA and spent time on the disabled list with back and elbow injuries.
REPLAY: The Cubs' modest two-game win streak was snapped with a 6-0 loss to the Dodgers on Wednesday night. The Cubs are 58-88 overall and have dropped 20 of their last 26 games.
Chicago mustered just seven hits on the night, with Aramis Ramirez leading the way with two. The Cubs have 16 games left and likely will suffer their first 90-loss season since 2002.
NOTES, QUOTESC Jose Reyes made his major league debut when he came into Wednesday's game against the Dodgers in the sixth inning. He went 0-for-2 with a strikeout.
RHP Angel Guzman once again failed to earn his first major league win when he gave up five runs in four-plus innings Wednesday. It's the seventh time in 10 starts he failed to go at least five innings.
RHP Wade Miller will make his second start of the season Thursday against the Dodgers. Miller had shoulder surgery performed last September and made his Cubs debut Saturday against Atlanta, lasting just three innings.
RHP Ryan Dempster blew his eighth save opportunity Tuesday night against the Dodgers, but he was the victim of bad luck when he gave up an unearned run in the ninth inning. SS Cesar Izturis and 1B Derrek Lee -- both past Gold Glove award winners -- committed errors in the inning.
2B Freddie Bynum's three errors against Los Angeles on Tuesday night marked the first time a Cubs fielder committed three errors since Shawon Dunston committed three against San Francisco on May 9, 1997.