Use of Dexmedetomidine for Deep Sedation in Patients Undergoing Outpatient Hysteroscopic Surgery

Overview

Patients undergoing deep sedation for outpatient procedures typically receive a combination of benzodiazepines, propofol, and opioids. Side effects of such anesthetics include respiratory depression, nausea and vomiting, and urinary retention, with resultant extended hospital stays and unanticipated admission. The use of dexmedetomidine for deep sedation may increase patient safety by maintaining respiratory drive, while providing sedation, hypnosis, and analgesia. Furthermore, patients may experience decreased pain, nausea, and time to discharge in the PACU, especially if dexmedetomidine decreases the requirement of other drugs such as opioids. The hypothesis of this study is administration of dexmedetomidine during deep sedation for ambulatory hysteroscopic surgery will result in a 50% reduction of intraoperative opioid compared to sedation with propofol.

Patients will be recruited up to 21 days prior to the day of surgery. Preoperatively: A full preoperative assessment will be completed. Preoperatively, patients will be instructed on the proper use of the verbal rating scale (VRS) for pain and nausea scores. Patients will be randomized by a computer-generated scheme to receive prepared infusions containing either dexmedetomidine (4grams per milliliter or propofol (10 milligrams per milliliter) intraoperatively. The study drug infusions will be prepared by study personnel who are not involved in the assessments. Patients, medical personnel other than the anesthesiologist, and outcome assessors will be blinded to treatment allocation. Only the anesthesiologist administering the treatment infusion and medications intraoperatively will be aware of group allocation. Intraoperatively: A standardized intraoperative anesthetic plan will be utilized by the anesthesia personnel.All patients will receive premedication with midazolam 2 milligrams intravenous bolus and ketorolac 30 milligrams via the intravenous catheter. Intraoperative monitoring will include standard monitoring which includes noninvasive blood pressure, electrocardiography, pulse oximetry, and capnography. In addition transcutaneous CO2 will be monitored using the Tosca monitor.(Radiometer, Basel, Austria). The study drug infusion will be started as either dexmedetomidine (1gram per kilogram over 10 min as a loading dose, followed by a maintenance infusion 0.2 to 1.5 grams per kilogram or propofol (started at 75gram per kilogram per minute and ranging from 12.5 to 125 gram per kilogram per minute titrated to maintain the Observer's Assessment of Alertness/Sedation Scale (OAA/SS) between 0-1. Intraoperative fluids will be restricted to 500 milliliter + 100mililiterml of Lactated Ringer's solution. At the onset of the procedure, the anesthesiologist will administer 0.7gram/kilogram bolus of fentanyl intravenous, followed by additional 25-50gram boluses for any patient movement to surgical stimulus. All patients will receive ondansetron 4 milligram IV 15-20 minutes prior to the end of surgery. Patients will receive glycopyrrolate 0.2 mg IV if HR decreases below 50 bpm. Postoperatively: In the recovery room, VRS for pain will be assessed upon admission and at 30 minute intervals thereafter. Analgesics will be administered according to the severity of the pain and degree of alertness.Vomiting and retching episodes.will be assessed at 30 minute intervals using a VRS, and patients with scores greater than 4 or those who request antiemetic treatment will be treated with metoclopramide 10 mg IV. Recovery from anesthesia and return of psychomotor ability will be assessed using the Modified Post Anesthesia Discharge Scoring System (MPADSS). A score of 8 or greater will indicate discharge readiness. Discharge readiness requires that a patient be awake and alert with stable vital signs, able to ambulate without assistance, and free of side effects. 24 hours after discharge. Times from end of surgery to oral intake and readiness for discharge, , and all adverse events and medications administered will be recorded. These data will be recorded by research staff blinded to the study group assignments. Subjects will be contacted by telephone 24 hours after surgery to obtain post-discharge data, including a repeat QoR-40 assessment.