(1) Objectives: Thiamine is a water-soluble vitamin of the B complex. First named aneurin for the negative neurological effects if not present in the diet, it was finally assigned the generic name vitamin B1. Thiamine plays a key role in certain metabolic reaction, including: nervous system and muscle functioning; flow of electrolytes in and out of nerve and muscle cells (through ion channels); multiple enzyme processes (via the coenzyme thiamin pyrophosphate); carbohydrate metabolism; and production of hydrochloric acid (which is necessary for proper digestion). Thiamine is generally considered safe and relatively nontoxic, even at high doses. Thiamine also helps convert carbohydrate to fat for storage of potential energy. Thiamine is a major factor in the metabolism of carbohydrate, fat, amino acid, glucose, and alcohol . It is a co-factor of pyruvate dehydrogenase and necessary for aerobic metabolism , that may increase oxygen extraction in critically ill patients. The purpose of this study was to evaluate the ability of intravenous thiamine for postoperative pain reduction in oral and maxillofacial surgery.
(2) Design: This is a double-blind randomised clinical trial study, that evaluate the effect of intraveneous thiamine on postoperative pain reduction in patients requiring maxillofacial surgery whom will be admitted in the Shiraz-chamran hospital. The following parameters such as: Individual patient information, medical history, the patient's hemodynamic values before- during and after surgery, duration of operation will be recorded. Severity of pain was evaluated by visual analoug scale (VAS) (100-mm) and the amount of opioid consumption after surgery, was recorded in maxillofacial ward. pain was measured after patient transfered to recovery room.
(3) Setting and conduct: A total of 50 adult patients were selected for this randomized controlled trial. All subjects were divided into two groups to receive thiamine or placebo. While anesthesiologist, and student project manager would be unaware of an intravenous drugs. ( Medications taken by nurses are randomly coded ). An informed consent approved by the Ethics Committee of the Shiraz University of Medical Sciences. The anesthesiologist administered 200 mg of thiamine intravenously with 20 cc of 5% dextrose solution in study group and in the control group patients received placebo (IV) with 20 cc of 5% dextrose solution. Blood pressure and heart rate will be monitored and anesthetic drugs requirements during surgery, postoperative pain and necessity for postoperative opioids immediately after surgery, in the recovery room and until 12 hours after operation will be calculated and recorded.
(4) Participants including major eligibility criteria: Inclusion criteria included 16-40year old patients whom were scheduled to undergo maxillofacial surgery؛ Subjects who had systemic disease and history of drug consumption, history of drug allergic reaction, hepatic and renal dysfunction and lack of signed informed consent will be excluded from the study sample .
(5) Intervention: Patients in the study group will be received an intravenous "Thiamine hydrochloride" 200 mg dissolved in Dextrose Water 5% via pump infusion bolus for 15 min and the placebo group will receive " Dextrose Water 5% " as same bolus volume in a 15-minute intravenous infusion.
(6) main outcome measures: During surgery heart rate, blood pressure and blood oxygen saturation is recorded at specified intervals and at the end of the operation analgesics usage were recorded. After surgery the patients were monitored for up to 4 hours in the recovery room and pain intensity (VAS 100-mm) is measured by a person who was uninformed about case and control groups every half hour. Pain relief drug consumption for patients will be recorded up to 12 hours in maxillofacial ward. post-operative complications will be asked in the questionnaire. Patient's satisfaction was evaluated as poor (0), moderate (1), good (2), and excellent (3).