METHODS	Postoperative pain therapy by i.v. PCA : group 1 morphine 0.75 mg.ml + ketorolac 0.75 mg.ml ; group 2 morphine 0.50 mg.ml + ketorolac 1.50 mg.ml ; group 3 morphine 0.25 mg.ml + ketorolac 1.50 mg.ml ; in saline solution .\