 a. Changes in mediator levels in the IV acetaminophen versus placebo groups will be compared. Plasma samples will be collected before administration of any drug after placement of IV lines, before incision, and 60 minutes after arrival in PACU. Blood 15millLiters will be collected at the time points described above from an additional intravenous catheter placed in the patients arm. These specimens will be placed in vacutainer tubes with no anti-coagulant. Blood will be drawn with a syringe attached directly to the angiocatheter which has been placed intravenously. To prevent hemolysis, blood will be transferred without a needle, to a vacutainer whose top has been removed. The vacutainer top will be replaced and specimens labeled with study name, subjects study IDentification number, sample number 1, 2, 3,, and dated. Bloods from the first two time points will be kept refrigerated until the final sample is obtained postoperatively. They will be centrifuged, serum removed, aliquoted and stored at -80 degrees C until analysis. All samples will be run in duplicate on with plates and reagents of the same lot. Any samples varying greater than 15 between duplicates 