The Effect of Dexmedetomidine on Hemodynamics, Platelet Aggregation and Intraoperative Blood Loss Under Sevoflurane Anesthesia During Total Hip Arthroplasty

Background: Sevoflurane is suggested to exert platelet anti-aggregation effect. Dexmedetomidine which is nowadays progressively used as anesthetic sparing was demonstrated experimentally to impair platelet aggregation. The purpose of the present work was to study the effect of addition of dexmedetomidine to both anesthetics on blood loss and platelet aggregation in total hip arthroplasty (THA) patients. Methods: We prospectively studied thirty adult ASA I-III patients, who were randomly allocated into two groups (15 patients each). Group (S) received sevoflurane, while group (SD) received sevoflurane anesthesia, with dexmedetomidine infused perioperatively as an adjunct to anesthesia. Hemodynamics (HR MAP), bleeding time, platelet count, intraoperative blood loss and platelet aggregation induced by ADP, Adrenaline and Collagen were assessed. Results: There was no statistically significant difference between the two groups as regards the platelet count or bleeding time. Blood loss was found to be statistically significant under evoflurane/Dexmedetomidine anesthesia, with no clinical deterioration of bleeding time or effect on blood loss. Intraoperative platelet aggregation was found to be impaired under both techniques, though more statistically significant in the Dexmedetomidine group. Dexmedetomidine still exerted inhibition of platelet aggregation 3 hours after anesthetic offset although much less inhibition was observed and limited to Adrenaline induced aggregation. Conclusion: In patients undergone THA, the present study showed that platelet aggregation was markedly depressed with the combination of Dexmedetomidine (as a loading dose of 1μg/kg/over 20 minutes, then continued at a dose of 0.2- 0.5μg/kg/hour) and inhaled anesthetic sevoflurane (1-2 vol. %) which was less significant under sevoflurane only, although clinical deterioration of bleeding time or blood loss was not observed, and this may be related to the relative reduction in blood pressure and heart rate under sevoflurane anesthesia and the more reduction under dexmedetomidine/sevoflurane anesthesia.