Comparison of the Effectiveness of Sedation With i.v. Dexmedetomidine in Combination With Midazolam Alone or Midazolam and Low Dose Ketamine for Extraction of Third Molars.

Subjects who have been screened medically and are scheduled for third molar surgery in the University of North Carolina (UNC)Oral and Maxillofacial Surgery (OMFS) clinic will be asked to volunteer for the study by the evaluating OMFS resident or attending physician. No additional x-rays will be taken other than those usually indicated for 3rd molar surgery. Informed consent will be obtained by study investigators.

Subjects will be instructed to fast for at least 8 hours prior to their appointment. Surgery will be performed in the Oral & Maxillofacial Surgery operating/sedation clinic where all monitoring equipment as well as emergency equipment is readily available, including the ability to ventilate the patient with oxygen (bag-mask), the ability to intubate, resuscitation drugs and equipment including a defibrillator. Patients will be positioned in a semi-reclining position in the dental chair and all monitors applied. A 20 gauge i.v. catheter will be placed and normal saline infusion attached. Supplemental oxygen will be administered via nasal cannula at 3 liters per minute. A picture will then be shown for recall testing. Pulse rate, arterial oxygen saturation (SpO2), respiratory rate, blood pressure, end-tidal CO2 (ETCO2), Ramsey Sedation Score (RSS sedation score) and Bispectral Index Scale (BIS) value will be recorded as a baseline and at 5 minute intervals during the procedure. Any SpO2 values below 90% as well as any episodes of apnea greater than 20 seconds will be recorded. Monitoring and recording of all data will be done by one of the investigators. Data will be recorded on pre-printed data forms. The surgical procedure will be performed by an oral and maxillofacial surgery resident physician.

Following the administration of 0.12 mg/kg of dexamethasone , dexmedetomidine will be infused at a rate of 6 mcg/kg/hr for four minutes; resulting in a loading dose of 0.4 mcg/kg. All of the above parameters will again be obtained and recorded. Patients will be randomly assigned by block randomization to receive either midazolam 0.04 mg/kg i.v. (50 patients), or midazolam 0.04 mg/kg plus 0.25 mg/kg of ketamine (50 patients). The operating surgeon and the patient will be blinded as to which protocol is being used. A dexmedetomidine infusion of 0.5 mcg/kg/hr will be initiated and continued until the completion of surgery. At this point local anesthesia will be administered in all four quadrants. Pain reaction during injections will be recorded. When efficacy of local anesthesia has been confirmed, surgery will commence. The surgery will be interrupted at 15 and 30 minutes to show a picture for recall testing by an investigator. If at any point the patient is deemed to be uncomfortable or uncooperative due to inadequate sedation, the protocol will be broken and additional sedation administered as per usual standards. The rescue therapy may include additional midazolam, ketamine, narcotic or propofol at the discretion of the anesthetist/sedationist. At the conclusion of surgery the dexmedetomidine infusion will be discontinued and the patient will be attended by a recovery nurse for collection of postoperative data. During recovery the physiologic parameters will be recorded at 10 minute intervals. When the patient achieves a recovery Aldrete score of >9, they will be asked by an investigator to recall pictures for amnesia assessment, and asked to assess patient satisfaction before leaving with an escort. The patient will be contacted on the day following surgery by phone or e-mail by one of the investigators to test for recall of pictures shown (amnesia testing) and patient satisfaction