Anesthesia and Competitive Strategies

Practice Patterns in Non–Operating Room Sedation

Sedation practice in the non–operating room setting varies widely throughout the world. This is exemplified by routine diagnostic GI endoscopy. In the United States, it is frequently assumed most patients want sedation for endoscopy. A study of U.S. gastroenterologists found that more than 98% of routine endoscopies are performed with sedation and approximately 25% of these providers now use propofol sedation. In addition, 68% of gastroenterologists using conventional sedation would consider using propofol if it were easily available. When propofol was used, it was provided by anesthesia-trained personnel in almost 90% of cases, with the remainder being directed by the endoscopist. Large regional variations are seen in the use of propofol from a low of 7% in the Northeast to a high of 37% in the Mid-Atlantic region. This variation appears to be driven by local reimbursement policies for sedation. In addition, an increasing number of more complex non–operating room procedures are performed in the United States. These factors have led to a dramatic increase in the need for high-quality sedation.

A review of sedation practice in 1998 revealed that in much of the world outside the United States and United Kingdom, the norm was for unsedated routine endoscopy. However, by 2006 this standard had begun to change in Europe; an observational study of 6004 patients undergoing colonoscopy found that 17% of patients had no sedation, 53% had moderate sedation, and 30% had deep sedation. More recently, Ladas et al collected data regarding the sedation rate for EGD and colonoscopy in Europe, North America, Asia, Africa, and Australia. No data were available from the last three continents, so questionnaire surveys were mailed to gastroenterologists in those locations. For upper GI endoscopy, rates of sedation varied in European countries from less than 20% to more than 75%; in the United States and Australia, over 98% of upper GI endoscopies were performed with sedation; in Asian countries many areas performed upper GI endoscopies without sedation, although some centers reported a 100% sedation rate. Finally, the surveys showed that 25% to 50% of patients received sedation in African countries. The authors note that the survey respondents reported that in as many as 46% of the countries, monitoring was not available in the majority of endoscopy suites; this lack of monitoring could be a factor in the low sedation rate. The rates of sedation for colonoscopy were shown to be quite variable among countries and among centers within each country. Sedation medication varied as well, although it was noted that propofol has been used in each country that responded to the survey. These data support an increasing expectation and use of sedation for endoscopy worldwide.

Propofol Use by Nonanesthesiologists

Propofol is used extensively in non–operating room sedation practice by both anesthesia-trained and nonanesthesiologist providers. Non–operating room settings where propofol frequently is given by nonanesthesiologists include the GI endoscopy suite, the electrophysiology laboratory, and, to a lesser degree, both diagnostic and interventional radiology areas. Propofol is a unique intravenous medication available as an oil-in-water emulsion for induction or maintenance of moderate-to-deep sedation and general anesthesia through facilitation of inhibitory neurotransmission mediated by gamma–aminobutyric acid (GABA). It is highly lipid-soluble, which results in an onset of action that is rapid; awakening from a single bolus dose is very rapid as well, because of a short initial redistribution half-life of 2 to 8 minutes. Propofol is cleared partly via hepatic conjugation and renal elimination of those inactive metabolites, but it also likely has a component of extrahepatic metabolism as the clearance of propofol exceeds hepatic blood flow. Propofol has many effects on the organ systems. It decreases arterial blood pressure as a result of a drop in systemic vascular resistance, cardiac contractility, and preload. It is a profound respiratory depressant and causes dose-dependent apnea while it inhibits hypoxic ventilatory drive and depresses the normal response to hypercarbia at sub–general anesthetic doses. It has antipruritic properties as well as antiemetic effects.

Propofol is preferred by many endoscopists and patients and has been shown in multiple studies to be associated with a faster induction of sedation and faster full recovery time, higher postprocedure patient satisfaction, and quicker anticipated return to baseline function. Dewitt et al demonstrated these findings in a prospective randomized, single-blinded trial of 80 consecutive patients who were randomized to receive either sedation with nurse-administered propofol sedation or midazolam and meperidine for EUS procedures. Nayar et al performed a retrospective analysis comparing outcomes of 1000 EUS procedures performed with anesthesia-assisted propofol sedation (propofol deep sedation) and 1000 EUS procedures performed under conventional sedation using midazolam and meperidine titrated to moderate sedation and found that sedation time, induction time, and intraprocedural time were significantly shorter in the propofol group. Randomized trials by Cohen, Sipe et al, and Ulmer et al that compared endoscopist-directed propofol (EDP) with traditional sedation with opioids and benzodiazepines in patients undergoing endoscopy or colonoscopy found that EDP resulted in faster onset of sedation, faster recovery, and similar or better patient satisfaction.

Not surprisingly, the use of propofol by non–anesthesia trained providers has led to some controversy. Anesthesiologists are concerned that propofol can induce general anesthesia and apnea very rapidly and that nonanesthesiologists lack sufficient airway expertise to rescue patients who receive propofol. The package insert for propofol states that propofol should be administered only by persons trained in rescue from unintended general anesthesia. At least 12 states in the United States have laws or regulations regarding nursing practice that prevent the administration of propofol to nonintubated patients. However, propofol has been and continues to be administered in the GI endoscopy suite without anesthesia-trained personnel. Several protocols have been described, but the generic term for this practice is nonanesthesiologist administration of propofol (NAAP). In the gastroenterology literature, it is also frequently referred to as EDP. Nonanesthesiologists believe that propofol is safe if used according to the principles that underlie safe procedural sedation with any agent—namely, slow titration to the desired level of sedation and awareness of individual variability in pharmacological response.

Two protocols for EDP sedation exist: nurse-administered propofol sedation (NAPS) and balanced propofol sedation (BPS). In NAPS a trained registered nurse’s sole responsibilities are patient monitoring and the administration of propofol, titrated to deep sedation. BPS combines several drugs in small doses, including fentanyl, midazolam, and propofol. Both the nurse and endoscopist participate in all dosing decisions that involve propofol. The nurse has primary responsibility for monitoring the patient, but the nurse also may perform brief tasks such as assisting with tissue acquisition. Both methods of sedation have been studied extensively, and gastroenterologists claim that these practices are safe for many patients.

Anesthesiologists counter that anesthesia care in remote locations, such as the GI endoscopy suite, poses a significant risk for the patient. This risk has been shown with data from the ASA closed claims database, with risks to the patient related to oversedation and ventilatory failure. The severity of these injuries was greater than those occurring within the operating room, and more than half of all sedation-related complications resulted in death. In addition, data from closed claims indicate that risk for complications increases when the number of agents used to provide sedation is greater than two. This may call into question the use of BPS by nonanesthesiologists, especially when a dedicated sedation provider is not used.