INTRAVENOUS KETOROLAC TROMETHAMINE WORSENS PLATELET-FUNCTION DURING KNEE ARTHROSCOPY UNDER SPINAL-ANESTHESIA

Ketorolac prolongs bleeding time and inhibits platelet aggregation and platelet thromboxane production in healthy, awake volunteers. However , platelet function was recently shown not to worsen after ketorolac w as given during general anesthesia. The purpose of this study was to i nvestigate platelet function changes during a standardized spinal anes thetic and surgery, as well as after a single intraoperative dose of i ntravenous (IV) ketorolac. The study comprised 30 ASA physical status I patients undergoing spinal anesthesia for knee arthroscopy. Subjects were randomized to receive either ketorolac 60 mg TV 15 min after ski n incision or placebo IV. Platelet function testing consisted of an Iv y bleeding time, platelet aggregometry with adenosine diphosphate (ADP ) and collagen, thromboelastography (TEG), and serum thromboxane B-2 ( TxB(2)) assays. Platelet function testing was performed: 1) 15 min pri or to the performance of spinal anesthesia; 2) 10 min after surgical s kin incision; and 3) 45 min after administration of study drug. The pl acebo group demonstrated no changes in any platelet function variable during spinal anesthesia and surgery relative to preoperative values. The ketorolac group, however, demonstrated a significant increase in b leeding time from postincision to poststudy drug data points (213 +/- 60 s to 275 +/- 85 s, mean +/- SD P < 0.01). Further, platelet aggrego metry to collagen was diminished in the ketorolac group from preoperat ive to poststudy drug data points (90.8% +/- 7.6% to 60.5% +/- 32.5%; P < 0.01). Platelet aggregometry with ADP, however, was unchanged in t he ketorolac group. Platelet TxB(2), production decreased dramatically in the ketorolac group from preoperative to poststudy drug data point s (157.2 +/- 129.4 to 0.3 +/- 0.3 ng/mL; P < 0.01). Platelet function does not appear to be accentuated during spinal anesthesia as it is du ring general anesthesia. Unlike during general anesthesia, platelet fu nction during spinal anesthesia is impaired, with respect to bleeding time and platelet aggregometry to collagen, by a single intraoperative dose of IV ketorolac.