Influence of hypotensive and normotensive anesthesia on platelet aggregability and hemostatic markers in orthognathic surgery

This prospective randomized study investigated the influence of normotensiv e and hypotensive general anesthesia on platelet aggregability, intraoperat ive blood loss and parameters of plasmatic coagulation during extensive ort hognathic surgery. A total of 30 patients were randomly allocated for eithe r normotensive anesthesia maintained by continuous infusion of propofol and remifentanil (NORMO, n = 10) or hypotensive anesthesia, whereby hypotensio n was induced by increasing the infusion rate of remifentanil (HYPO-R, n = 10) or by administration of nitroglycerin (HYPO-N, n = 10). Whole blood pla telet aggregability was significantly reduced during hypotension compared t o normotensive anesthesia (P < .01, HYPO-N and HYPO-R vs. NORMO). Mean arte rial blood pressure during hypotension correlated well with adenosinediphos phate (R = .712, P < .001) and collagen-induced platelet aggregability (R = .685, P < .001). Within hypotensive study groups, postoperative fibrinogen levels were significantly different, whereas intraoperative platelet aggre gability, postoperative platelet count, prothrombin time, activated partial thromboplastin time and antithrombin levels were not different. Normotensi ve anesthesia, however, caused significant decreases in platelet count (-29 %), prothrombin time (-24%), fibrinogen (-41%) and antithrombin (-28%) and a significant prolongation in activated partial thromboplastin time (+21%) and thrombin time (+18%). There was a trend to reduced intraoperative blood loss in hypotensive study groups; however, differences were not significan t. In conclusion, induced hypotension - independent of substances used for induction of hypotension - reduces intraoperative platelet aggregability, s ubsequently protecting the coagulation system against subclinical consumpti on coagulopathy. Induced hypotension-caused platelet dysfunction does not l ead to an increased intraoperative blood loss, but quite on the contrary sh ows a trend to reduced intraoperative blood loss, possibly by preventing pl atelet-induced subclinical consumption coagulopathy. (C) 2001 Elsevier Scie nce Ltd. All rights reserved.