EMPLOYEE WAS ATTEMPTING TO SHORTEN A PLASTIC DRAIN LINE WITH A POCKET KNIFE. SHE WAS HOLDING THE TUBING IN A ""U"" POSITION AND ATTEMPTED TO PUSH THE KNIFE AWAY FROM HER TO COMPLETE A CUT. HER L EFT INDEX FINGER WAS STABLIZING TUBE AND KNIFE CUT THROUGH TUBING INTO TOP OF FINGER. LACERATION REQUIRING THREE SUTURES.