The effects of normotensive anesthesia and controlled hypotensive anesthesia upon platelet aggregation

This study aimed to compare the effect of controlled hypotensive anesthesia using esmolol upon platelet functions with normotension desfuranremifentanil anesthesia in the PFA-100 system. After receiving the approval of the faculty ethics committee, 30 ASA I-II risk status patients to be undergoing middle ear surgery, who were informed and from whom written consent was received, were included in the study. General anesthesia was induced by 0.5 mg.kg?1 lidokain hydrochloride, 0.5 ?g.kg-1 remifentanil, 5?7 mg.kg?1 Na-tiyopental and 0.6 mg.kg?1 rocuronium intravenously, and maintained after endotracheal intubation with desflurane and remifentanil in all patients. After intubation when hemodynamic stabilization was sustained, the target mean arterial pressure (MAP) (55-65 mmHg) levels were obtained in the hypotensive group (Group H) with the infusion of esmolol, the doses of which ranged between 50-300 ?g.kg-1dk-1, before surgery and after 0.5 mg iv bolus. The infusion of esmolol was ended after the microscopic process was finished. In the control normotensive group (Group N), MAP was continued between 80-90 mmHg and in all patients desflurane-remifentanil anesthesia was administered for the maintenance. Peroperative hemodynamic variables, unwanted effects and hourly urine quantities were recorded. PFA-100 Collogen/ADP and Collogen/Epinephrine durations before induction, at the 60th minute of surgery and hypotension and after surgery were examined. An analysis was made of arterial blood gas at the end of induction, at the 60th minute of hypotension and surgery and at the end of surgery, and the Hb and Htc values were recorded. In statistical analyses p<0.05 was regarded significant. No statistical difference was observed between the groups regarding patient characteristics and presurgical hematological tests. The total amount of remifentanil used, the average remifentanil dose and hourly urine quantity were found significant in Group H. In between-group analysis, there was significant difference in systolic-diastolic-mean blood pressure, and heart rate at all measurment during the observation period. The average Hb and Htc values at 3 measurement times were found to show similarity between the groups. When PFA-100 closure times were compared at the 60th minute and at the end of the surgery, the Collogen/ADP durations in Group H was observed to be significantly longer than that in Group N (p <0.05). The Collogen/Epi durations in Group H was observed to be significantly longer than that in Group N at the 60th minute and at the end of the surgery (p<0.001, p< 0.01,respectively). The Collogen/ADP durations in Grup H was observed to be significantly longer than that in control at the 60th minute of the surgery ( p<0.001) and at the end of the surgery it was lower in Group N compared to control (p<0.01). The amount of blood loss in Group H was found to be significantly lower than that in Group N (p<0.001). When the appearance of the surgical sites were compared, in 10 out of 15 patients (66.7%), there was bad surgical site appearance, and in the remaining 5 patients (33.7%) a good surgical site appearance was obtained. There was no difference between two groups for patient satisfaction. In this homeostasis study carried out on patients whose general health conditions was good, who did not have bleeding disorders and who were not using any drugs, we found that hypotensive anesthesia, formed by adding esmolol to desfluran-remifentanil normotensive anesthesia, caused reflexive inhibition in platelet functions. Consequently, we believe that desflurane remifentanil normotensive anesthesia, instead of hypotensive anesthesia, would be a more appropriate preference in patients under the risk of intraoperative bleeding risk; however, in patients under the high risk of thrombosis, it would be appropriate to administer hypotensive anesthesia with esmolol.