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The effect of pre-induction clonidine on platelet aggregation during minor surgery
E A Akpek1, S Kahraman, A Yaman
1Department of Anaesthesiology, Hacettepe University Medical School, Ankara, Turkey.
Objective:
This paper reports the results of a prospective randomized double-blind trial on the effects of pre-operative clonidine on platelet aggregation.
Methods:
Thirty adult (ASA I-II) patients undergoing elective minor orthopaedic surgery were randomly allocated into three groups of ten patients each. In group I clonidine 2 microg x kg(-1), in group II clonidine 4 microg x kg(-1) and in group III saline placebo was administered intravenously before the induction of anaesthesia. Anaesthesia was induced with propofol and vecuronium and maintained with halothane-nitrous oxide. Platelet counts and aggregation tests were performed before (t0) and 1 h (t1) and 24 h (t24) after administration of the study drug.
Results:
Changes in platelet counts among the groups and values over time were not significant. Both maximum rate and intensity of collagen-induced aggregation in both clonidine groups and maximum intensity of adenosine 5'-diphosphate (ADP)-induced aggregation in the high-dose clonidine group increased significantly at t1. However, all these increases in aggregation were within the normal ranges.
Conclusion:
The effects of both low and high doses of clonidine on platelet aggregation appeared to be minor, and we did not observe any increases above the normal ranges.