Anesthesiologists are usually consulted when any of the following pertinent items in the history are obtained: an obvious/known difficult airway, a previous failed sedation by the gastroenterology team, problems associated with prior anesthetic exposure, morbid obesity, stridor, snoring, sleep apnea, gastroesophageal reflux/aspiration risk and procedures performed in the prone position. Patients may be tolerant to sedative medications if they are chronic users of benzodiazepines, narcotics, alcohol or other drugs. Patients with neurologic diseases may be more susceptible to sedative medications and may hypoventilate. Patients with psychiatric disorders or extremely anxious patients may not cooperate during the procedure. Patients who have had a previous unsatisfactory experience with sedation for this procedure may request general anesthesia. Patients who have a known difficult airway or who have features suggestive of a difficult airway/difficult mask (small mouth opening; head and neck cancer patients, particularly after radiation therapy; patients with cervical fusions and limited airway/extension of the neck) are frequently scheduled with an anesthesiologist from the beginning. (Cole & Schlunt, 2004, p. 393)