Objectives: To evaluate the effect of clonidine as a single dose oral preoperative medication on surgical blood loss in posterior spinal fusion surgery and compare it with that of placebo
Design: double-blinded randomized clinical trial
Setting and conduct: 30 patients candidated for lumbar spine posterior fusion at 3-4 levels, in Rassoul e Akram hospital (Tehran (previous Iran) university of medical sciences); are randomly allocated into 2 groups. The study group (Clonidine group) receive 200micg oral clonidine tablet 60-90 minutes before anesthesia and the control group receive placebo at the same time. Induction and maintenance of anesthesia and the target mean arterial pressure for controlled hypotension with remifentanil are the same in the 2 groups. We compare the amount of blood loss, dose of remifentanil /hour administered, need for nitroglycerine to reach the target mean arterial pressure when remifentanil was not enough, duration of operation and surgeon's satisfaction of a bloodless field between the 2 groups.
Participants including major eligibility criteria: 20-65yr old with American Society of Anesthesia (ASA) physical status of I-II candidated for posterior fusion of lumbar spine at 3 to 4 levels due to traumatic vertebral fracture; who don't have any significant underlying disease (hypertension, hepatic or renal disease, coagulation defects, diabetes mellitus), beta-blocker, calcium channel blocker, dioxin, tricyclic antidepressant, anticoagulant or clonidine treatment, drug or alcohol abuse.
Intervention: 200 microgram Clonidine tablet administered to the patients in intervention group as a single dose, 60 to 90 minutes before anesthesia
Main outcome measures (variables): The amount of blood loss during operation, dose of remifentanil /hour administered, need for nitroglycerine to reach the target mean arterial pressure when remifentanil is not enough, duration of operation and surgeon's satisfaction of a bloodless field