VanNatta and Rex from Indiana compared four sedation regimens in a group of outpatients undergoing colonoscopy.66 In each group the propofol dose was titrated according to sedation requirements: (i) propofol alone; (ii) fentanyl (50 µg with an optional further 25 µg being given subsequently for pain at the discretion of the endoscopist) and propofol; (iii) midazolam (1 mg) and propofol and (iv) all three of fentanyl (50 µg), midazolam (1 mg) and propofol. Where combination sedation was used, in each case, propofol was administered last. Those receiving propofol alone had the deepest sedation scores and received on average 215 mg of the drug

compared with 82.5 mg in those receiving antecedent doses of both midazolam and fentanyl. Propofol requirements in the other two groups were 140 mg (fentanyl selleck inhibitor alone group) and 125 mg (midazolam alone group). Those in the combination groups were discharged from hospital more quickly. Those in the fentanyl combination group remembered more pain associated with the procedure than those given propofol alone. This study is noteworthy for there being an almost 50% reduction in propofol requirements with only 1 mg of midazolam. Compared with the Australian study,37 the MG132 doses of fentanyl and particularly

midazolam were lower with correspondingly higher propofol requirements. Interpretation of the Indiana study must be guarded in view of the small numbers (200 patients in total). Careful administration of appropriately adjusted doses, particularly to the frail and the elderly, is essential

if unwanted cardiorespiratory depression is to be avoided during endoscopy. There is evidence that supplemental oxygen reduces the risk of hypoxemia during colonoscopy,67 although there are concerns that when supplemental oxygen is administered, oxygen saturation levels no longer reflect ventilatory function and may mask CO2 retention.68 Nonetheless, a recent Australian survey of anesthetists revealed that the use of supplemental oxygen was universal.36 Expertise in managing airway obstruction and apnea is essential. Measures undertaken include chin lift, jaw thrust, placement of oral and nasal airway STK38 tubes, and for more prolonged periods of respiratory compromise, bag and mask ventilation. Reversal agents, including noloxone and flumazenil, are occasionally indicated. More advanced life support measures, including the use of laryngeal masks and endotracheal intubation are very rarely required in the ambulatory setting.5 For patients developing hypotension related to sedation agents, intravenous fluids may be indicated. For endoscopic procedures carried out in hospitals, ready access to a ‘Medical Emergency’ button is recommended. Traditionally, endoscopists have either given sedation themselves before and sometimes during procedures or have directed nursing staff to do this.