EFFECT OF KETOROLAC TROMETHAMINE ON BLEEDING AND ON REQUIREMENTS FOR ANALGESIA AFTER TOTAL KNEE ARTHROPLASTY

The effect of ketorolac tromethamine, a non-steroidal anti-inflammator y drug, on postoperative blood loss and on the requirement for morphin e was assessed after total knee arthroplasty, an operation in which bl ood loss is mainly measured rather than estimated. The purpose of this prospective, randomized, double-blind clinical trial was to determine whether administration of ketorolac in the perioperative period would increase bleeding related to the operation. Fifty-nine patients who h ad a total knee arthroplasty received either thirty milligrams of keto rolac or a placebo consisting of saline solution, intravenously, every six hours, in four doses. The first dose was administered about an ho ur before the end of the operation. Blood loss and use of morphine for pain control were measured for the first twenty-four hours postoperat ively. The per cent change in the hematocrit and the amount of transfu sed blood were also recorded. The patients who received ketorolac used 27 per cent less morphine than those who received the placebo (40.0 /- 23.4 milligrams compared with 55.1 +/- 23.5 milligrams [mean and st andard deviation]); this difference was significant (p < 0.05). On the first day after the operation, the hematocrit decreased from 0.364 +/ - 0.043 preoperatively to 0.278 +/- 0.032 in the patients who received ketorolac and from 0.363 +/- 0.046 to 0.298 +/- 0.030 in the patients who received the placebo. The 6 per cent greater decrease in the grou p that received ketorolac was significant (p < 0.05) but not clinicall y important. There were no important differences between the two treat ment groups with respect to the blood loss, amount of transfused blood , or change in the hematocrit on the second postoperative day. An incr eased tendency for postoperative bleeding could be a serious problem i n patients who receive a 120-milligram dose of ketorolac daily and rou tine anticoagulation for prophylaxis against thromboembolism. It is th erefore meaningful that ketorolac, given in four thirty-milligram dose s, did not increase postoperative blood loss but was associated with d ecreased use of morphine. Ketorolac appears to be both safe and effect ive? for use as a component of therapy for pain after total knee repla cement.