Key points

Terminology surrounding endoscopist-directed propofol

Endoscopist-directed propofol (EDP) was a term that developed late in the history of propofol administration without involvement of anesthesia specialists. The term “EDP” was meant in part to emphasize that the process of delivering propofol without the involvement of anesthesia specialists remains under the control of, direction of, and the responsibility of the endoscopist. As such, EDP encompasses and includes the earlier term nurse-administered propofol sedation (NAPS). The introduction of NAPS for endoscopy to the United States is credited to John Walker, a private practice gastroenterologist in Medford, Oregon. With the cooperation and direction of an anesthesiologist working in his surgery center, Dr Walker developed protocols for registered nurses to carefully titrate propofol as a single agent for endoscopic procedures. Many early adopters, including myself, began the administration of propofol without anesthesia specialists by traveling with key nurses to Medford, Oregon, to observe Dr Walker’s practice of NAPS.

Despite the remarkable success and safety record of Dr Walker’s program, it became clear that propofol as a single agent was very difficult to use outside of deep sedation or general anesthesia. Although some groups have titrated single-agent propofol to moderate sedation, most endoscopists feel that initiating upper endoscopy in a patient sedated with propofol alone while still in moderate sedation results in marked coughing and gagging. The natural impulse is then to administer additional propofol and push the patient into deep sedation or general anesthesia. Colonoscopy with single-agent propofol is safer and easier compared with upper endoscopy, but in moderate sedation with single-agent propofol, colonoscopy patients may posture and move, and the typical inclination is to push the patient into deep sedation. “Balanced propofol sedation” (BPS) was developed specifically to allow propofol to be titrated to moderate sedation. The key to achieving moderate sedation in BPS is to administer a small amount of an opioid and/or benzodiazepine before the first dose of propofol. Some experts have argued that the potential for synergism between drugs in different classes creates excessive risk with combination therapy that should be avoided. However, any such assertion reflects an insufficient experience with using propofol in combination with other agents for procedural sedation, as combination therapy virtually enables the targeting of propofol to moderate sedation. During upper endoscopy, fentanyl blocks the tendency of patients to cough, and during colonoscopy, fentanyl provides some pain relief, whereas a benzodiazepine (almost always midazolam) provides excellent amnesia for the patient in moderate sedation. Further, the opioid and benzodiazepine block the posturing and withdrawal responses when procedures are performed in moderate sedation with single-agent propofol. During BPS, doses of fentanyl are typically 50 to 75 μg, and midazolam doses are 1 to 2 mg. Following the initial dose of opioid and/or benzodiazepine, all further doses are with propofol. During BPS, both upper endoscopy and colonoscopy can be carried out at the level of the moderate sedation, and the total dose of propofol is usually reduced by half or more compared with the amount of propofol administered as a single agent. Dosing of propofol in BPS is less frequent compared with single-agent propofol, which reduces stress for the individual who is titrating the drug.

In our experience, we settled into a pattern of using BPS for all upper endoscopic procedures and for all colonoscopies that we considered at higher risk for airway obstruction, such as patients with obesity or obstructive sleep apnea. For thin patients with low-risk airways, we often used single-agent propofol for colonoscopy, as the risk of airway obstruction or prolonged apnea in thin patients with low-risk airways during colonoscopy was almost negligible in our experience. This was true despite our consistent targeting of deep sedation when using single-agent propofol. Both NAPS in any format, as well as BPS, are encompassed under the term EDP. The simple requirement for EDP is the administration of propofol by a registered nurse (occasionally by the endoscopist), with supervision by the endoscopist, without any involvement of anesthesia specialists (either an anesthesiologist or a nurse anesthetist).

Terminology surrounding endoscopist-directed propofol

Endoscopist-directed propofol (EDP) was a term that developed late in the history of propofol administration without involvement of anesthesia specialists. The term “EDP” was meant in part to emphasize that the process of delivering propofol without the involvement of anesthesia specialists remains under the control of, direction of, and the responsibility of the endoscopist. As such, EDP encompasses and includes the earlier term nurse-administered propofol sedation (NAPS). The introduction of NAPS for endoscopy to the United States is credited to John Walker, a private practice gastroenterologist in Medford, Oregon. With the cooperation and direction of an anesthesiologist working in his surgery center, Dr Walker developed protocols for registered nurses to carefully titrate propofol as a single agent for endoscopic procedures. Many early adopters, including myself, began the administration of propofol without anesthesia specialists by traveling with key nurses to Medford, Oregon, to observe Dr Walker’s practice of NAPS.

Despite the remarkable success and safety record of Dr Walker’s program, it became clear that propofol as a single agent was very difficult to use outside of deep sedation or general anesthesia. Although some groups have titrated single-agent propofol to moderate sedation, most endoscopists feel that initiating upper endoscopy in a patient sedated with propofol alone while still in moderate sedation results in marked coughing and gagging. The natural impulse is then to administer additional propofol and push the patient into deep sedation or general anesthesia. Colonoscopy with single-agent propofol is safer and easier compared with upper endoscopy, but in moderate sedation with single-agent propofol, colonoscopy patients may posture and move, and the typical inclination is to push the patient into deep sedation. “Balanced propofol sedation” (BPS) was developed specifically to allow propofol to be titrated to moderate sedation. The key to achieving moderate sedation in BPS is to administer a small amount of an opioid and/or benzodiazepine before the first dose of propofol. Some experts have argued that the potential for synergism between drugs in different classes creates excessive risk with combination therapy that should be avoided. However, any such assertion reflects an insufficient experience with using propofol in combination with other agents for procedural sedation, as combination therapy virtually enables the targeting of propofol to moderate sedation. During upper endoscopy, fentanyl blocks the tendency of patients to cough, and during colonoscopy, fentanyl provides some pain relief, whereas a benzodiazepine (almost always midazolam) provides excellent amnesia for the patient in moderate sedation. Further, the opioid and benzodiazepine block the posturing and withdrawal responses when procedures are performed in moderate sedation with single-agent propofol. During BPS, doses of fentanyl are typically 50 to 75 μg, and midazolam doses are 1 to 2 mg. Following the initial dose of opioid and/or benzodiazepine, all further doses are with propofol. During BPS, both upper endoscopy and colonoscopy can be carried out at the level of the moderate sedation, and the total dose of propofol is usually reduced by half or more compared with the amount of propofol administered as a single agent. Dosing of propofol in BPS is less frequent compared with single-agent propofol, which reduces stress for the individual who is titrating the drug.

In our experience, we settled into a pattern of using BPS for all upper endoscopic procedures and for all colonoscopies that we considered at higher risk for airway obstruction, such as patients with obesity or obstructive sleep apnea. For thin patients with low-risk airways, we often used single-agent propofol for colonoscopy, as the risk of airway obstruction or prolonged apnea in thin patients with low-risk airways during colonoscopy was almost negligible in our experience. This was true despite our consistent targeting of deep sedation when using single-agent propofol. Both NAPS in any format, as well as BPS, are encompassed under the term EDP. The simple requirement for EDP is the administration of propofol by a registered nurse (occasionally by the endoscopist), with supervision by the endoscopist, without any involvement of anesthesia specialists (either an anesthesiologist or a nurse anesthetist).

Basic principles of endoscopist-directed propofol

Whether propofol is used as a single agent or as the core drug in BPS, the basic principles of its administration are similar. In BPS, the doses administered should be approximately half of those used when administering propofol as a single agent. The optimal method of administering propofol to maximize safety in EDP is different from the way I commonly see it used by anesthesiologists. Anesthesia specialists often use propofol as an induction agent in the United States before general anesthesia. As such, they frequently give a single bolus of 100 to 200 mg, which frequently induces coma and apnea. Although I see anesthesia specialists safely administer similar doses when using propofol for endoscopic procedures, this is not the best way to achieve a good safety record in EDP.

The principal factor governing dosing in EDP is that the drug has no reversal agent. If enough propofol is given as a single bolus, one can induce apnea and general anesthesia for a number of minutes, certainly long enough to have a very bad outcome in the absence of effective resuscitation. The key to safety with EDP is to titrate the dose and avoid overshooting as much as possible. If done effectively, cautiously, and with constant monitoring of the sedation level and ventilation, any overshoot will be very brief. In effect, with appropriate caution in the titration of propofol, there is no need for a reversal agent because the short duration of action of propofol ensures a brief duration for any apnea that is induced.

In our practice, we limited initial doses of propofol to 50 mg or less. In small, elderly, or frail patients, and those with multiple comorbidities, initial boluses were commonly 20 to 30 mg. After the initial bolus, a useful rule developed by Ludwig Heuss and colleagues was the 20/20 rule, which is no more than 20 mg of propofol administered at an interval no shorter than every 20 seconds.

Colonoscopy can be done with an initial bolus of propofol followed by an intravenous infusion. However, for upper endoscopy and colonoscopy, our observation was that bolus administration throughout provided the best speed to initial intubation and less likelihood of full arousal during the procedure. As noted, the frequency of bolus administration is reduced and therefore administration is simplified compared with bolus titration with single-agent propofol. Training in procedural sedation is covered elsewhere in this issue (see Ben Da, James Buxbaum: Training and Competency in Sedation Practice , in this issue), but training in EDP should follow recommended training guidelines.

Colonoscopy technique is somewhat different in deep sedation compared with moderate sedation. In particular, there tends to be more reliance on abdominal pressure compared with position change to advance the colonoscope during insertion.