Anesthesia for ERCP: Clinical Practice and Safety Aspects

Authors: Daniel Wolfe, MD, Assistant Professor, University of Arkansas for Medical Sciences, Little Rock, AR, and Sorin J. Brull, MD, Professor, University of Arkansas for Medical Sciences, Little Rock, AR.

Peer reviewer: E. Christopher Ellison, MD, Robert M. Zollinger Professor and Chairman, Department of Surgery, The Ohio State University, College of Medicine and Public Health, Columbus, OH.

Same-Day Surgery Reports

A number of factors have interacted to encourage the participation of anesthesiologists and other anesthesia providers in endoscopic retrograde cholangiopancreatography (ERCP) procedures. First, the increased scrutiny of sedation procedures has prompted gastroenterologists to be more cautious in their approach to sedating patients for endoscopic procedures. Second, the Park Ridge, IL-based American Society of Anesthesiologists (ASA) (www.ASAhq.org) and the Joint Commission on Accreditation of Healthcare Organizations (www.JCAHO.org) have reclassified the levels of sedation as a continuum consisting of: (1) minimal sedation (anxiolysis), (2) moderate sedation/analgesia ("conscious sedation"), (3) deep sedation/analgesia, (4) general anesthesia.

This reclassification has prompted the realization that ERCP, more so than other endoscopic procedures, often requires deep sedation/analgesia to facilitate patient cooperation. Third, the introduction and popularity of propofol have made its use a widespread technique for sedation in the endoscopy suite, and many facilities limit the use of propofol to anesthesiologists. Finally, the most recent Joint Commission standards for sedation1 dictate that supervising physicians have the ability to "rescue" their patients from one level of sedation deeper than the target level.

If deep sedation/analgesia is necessary for ERCP, then the supervising physician must be able to rescue the patient from the unintended foray into general anesthesia.

Few gastroenterologists are willing to shoulder the responsibility for managing a general anesthetic, even if it is brief and/or unintentional. In response to the above considerations, many endoscopists are requesting anesthesiologists’ services to help ensure the comfort and safety of their patients undergoing ERCP and to comply with the newly published Joint Commission standards.

Location of Procedure

Having accepted responsibility for the anesthetic management of the ERCP patient, the anesthesiologist is faced with a number of problems unique to this procedure. First is the anesthetizing location for the patient. The Joint Commission initially established an Ambulatory Health Care accreditation program in 1975 in an attempt "to encourage quality patient care in all types of freestanding ambulatory care facilities." Today, ERCPs are performed at sites ranging from the gastroeneterologist’s office to the main operating room of a hospital. Ensuring the safe provision of anesthesia often will require the physician/anesthesiologist to evaluate, and if needed, upgrade the facility where the procedure is performed. Various ASA policy documents, including the Guidelines for Ambulatory Anesthesia and Surgery,2 suggest that all anesthetics should be delivered by, or under the medical direction of, an anesthesiologist.

ASA recognizes, however, that Medicare regulations allow that where anesthesiologist participation is not practicable, nonphysician anesthesia providers must, at a minimum, be supervised by the operating practitioner or other licensed physician.

Furthermore, ASA believes that specific anesthesia training for supervising operating practitioners or other licensed physicians, while important in all anesthetizing locations, is especially critical in connection with office-based surgery, where normal institutional backup or emergency facilities and capacities often are not available.

Regardless of the type of anesthetic chosen, the location where ERCPs are performed should be upgraded to comply with the ASA guidelines for the provision of general anesthesia. These guidelines include the Standards for Basic Anesthetic Monitoring,3 which can be accessed at the ASA web site, www.asahq.org, or by writing to the ASA directly (Headquarters Office, 520 N. Northwest Highway, Park Ridge, IL 60068-2573). Additionally, the following ASA documents are extremely helpful and should be consulted if anesthesia for ERCP is to be given outside the hospital environment:

  • Guidelines for Office Based Anesthesia;4
  • Guidelines for Ambulatory Anesthesia and Surgery;2
  • Guidelines for Nonoperating Room Anesthetizing Locations.5

Existing Joint Commission regulations make compliance with these standards mandatory for hospitals, should general anesthesia be anticipated as an option during ERCP. Even if deep sedation is the only anticipated anesthetic modality for ERCP, the recent Joint Commission requirements mandate that the capability to rescue patients from the next deeper stage of sedation be available.1

These standards thus dictate the use of a facility at which administration of general anesthesia is possible, if only for a short time. At the least, current guidelines encourage upgrading anesthetic locations to meet the requirements of provision of general anesthesia care.1 (See "Patient Positioning, Preoperative Evaluation, Patient Selection for ERCP" in this issue.)

Equipment and Monitoring

Appropriate equipment for provision of safe patient care and resuscitation must be available. Monitoring equipment capable of measuring vital signs (heart and respiratory rates), oxygenation (pulse oximetry equipment), pulmonary ventilation (capnography), and body temperature should be available.3

The primary causes of morbidity associated with sedation/ analgesia are drug-induced respiratory depression and airway obstruction.6,7 Monitoring of ventilatory function by observation or auscultation reduces the risk of adverse outcomes associated with sedation/analgesia, and the use of supplemental oxygen markedly reduces the risk of hypoxia during the procedure.8 In circumstances in which patients are physically separated from the caregiver, automated apnea monitoring (by detection of exhaled CO2 or other means) may decrease risks during both moderate and deep sedation;9 impedance plethysmography, however, may fail to detect airway obstruction.10 Since ventilation and oxygenation are separate — though related — physiological processes, monitoring oxygenation by pulse oximetry is not a substitute for monitoring ventilatory function.11 Published data also suggest that oximetry effectively detects oxygen desaturation and hypoxemia in patients who receive sedatives and/or analgesics.11-13

Early detection of hypoxemia (which is more likely to be detected by oximetry than by clinical assessment alone) during sedation/analgesia decreases the likelihood of adverse outcomes such as cardiac arrest and death.8 The recent introduction of bispectral index monitoring (as an attempt to provide an objective measure of sedation level by measuring cerebral activity) may further improve the efficacy and safety of ERCPs performed with sedation.14

The patient’s response to care provided throughout the sedation-supported procedure should be documented in the patient’s record. The Joint Commission standards suggest that outcomes of patients undergoing moderate and deep sedation be collected and analyzed in the aggregate to identify opportunities to improve care.1

Anesthetic Technique

The combination of a sedative with an opioid provides effective moderate sedation; it is equivocal, however, whether the combination of a sedative and an opioid may be more effective than a sedative or an opioid alone in providing adequate moderate sedation.15,16

For deep sedation, the literature is insufficient to compare the efficacy of sedative-opioid combinations with that of a sedative alone. Combinations of sedatives and opioids, administered judiciously and with appropriate monitoring, provide satisfactory moderate and deep sedation. However, the published data also suggest that combinations of sedatives and opioids may increase the likelihood of adverse outcomes including ventilatory depression and hypoxemia.7

Fixed combinations of sedative and analgesic agents may not allow the individual components of sedation/analgesia to be appropriately titrated to meet the individual requirements of the patient and procedure while reducing the associated risks.16 Thus, each agent should be administered individually to achieve the desired effect (e.g., additional analgesic medication to relieve pain; additional sedative medication to decrease awareness or anxiety). The propensity for combinations of sedative and analgesic agents to cause respiratory depression and airway obstruction underscores the need to reduce the dose of each combination agent as well as the need to continually monitor respiratory function and level of consciousness.15,17

Current scientific data are insufficient to determine whether administration of small, incremental doses of intravenous sedative/analgesic drugs is preferable to a single bolus dose based on patient size, weight, or age. There are, however, studies that have shown good sedation results under a continuous (target-controlled) infusion of agents.18 It is generally agreed, however, that incremental drug administration improves patient comfort and decreases risks for both moderate and deep sedation.9,18 Intravenous sedative/analgesic drugs should be given in small, incremental doses that are titrated to the desired endpoints of analgesia and sedation, and sufficient time must elapse between doses to allow the effect of each dose to be assessed before subsequent drug administration.17,19

There are several anesthetic induction agents that can be used safely for sedation and analgesia (propofol, methohexital, and ketamine). Literature suggests that when administered by nonanesthesiologists, propofol and ketamine can provide satisfactory moderate sedation (in the emergency department), while methohexital can provide satisfactory deep sedation.18,20 The literature, however, is insufficient to evaluate the efficacy of propofol or ketamine administered by nonanesthesiologists for deep sedation, or to unequivocally prove whether moderate or deep sedation with propofol is associated with a different incidence of adverse outcomes than similar levels of sedation with midazolam.

The one prospective, randomized study that evaluated sedation with propofol plus midazolam vs. propofol alone for ERCP found that propofol allowed faster post-procedure recovery than the combination.21 It also must be noted that ketamine, methohexital, and propofol can produce rapid, profound decreases in level of consciousness and cardiorespiratory function, potentially culminating in a state of general anesthesia. Although it may be associated with less cardiorespiratory depression than other sedatives, ketamine nevertheless can induce airway obstruction, laryngospasm, and pulmonary aspiration of gastric contents. Furthermore, because of its dissociative properties, some of the usual signs of depth of sedation may not apply when ketamine is used (e.g., the patient’s eyes may be open while in a state of deep sedation or general anesthesia).

The practitioners also must note that there are no specific pharmacological antagonists for any of these medications. Accordingly, practitioners administering ketamine, methohexital, or propofol should be qualified to rescue patients from any level of sedation, including general anesthesia.

If deep sedation is used for ERCP, propofol is an ideal medication to maintain adequate sedation and adequate spontaneous respiration. The transient effect of propofol allows it to be given as a continuous infusion for precise titration of the depth of sedation. Once the infusion is stopped, the rapid recovery from sedation with propofol is a significant safety factor that makes the use of propofol more attractive, as are its mild anti-emetic properties. Premedication with droperidol also has been shown to be effective in decreasing the postoperative nausea and vomiting.22 The rapid recovery from sedation and effective antiemetic therapy facilitate room turnover and timely discharge in the outpatient setting. Careful topical anesthesia of the mouth and oropharynx should be used when sedating a patient for ERCP. Significantly less medication is necessary to produce sedation if the stimulus of the endoscope passing through the mouth is ablated. Any of the topical anesthetic formulations available for use on the mucous membranes should be adequate for this purpose.

The practitioners should bear in mind that topical oral anesthesia inevitably will impair the normal gag reflex and consequently increase the risk of aspiration in susceptible patients.23 The patient should be positioned and all pressure points carefully padded during the procedure, but providers should remember that ERCP procedures can sometimes last as long as three hours. A deeply sedated patient is unlikely to maintain protective reflexes against pressure necrosis and, therefore, is at particular risk for injury due to improper positioning.

Appropriate IV access with readily available injection ports is critical to this procedure, as with any other anesthetic. Supplemental oxygen should be supplied via nasal cannulae, and some means of monitoring end-tidal CO2 must be used to assess the maintenance of adequate ventilation. Pulse oximetry, blood pressure, and continuous ECG monitoring should be maintained throughout the procedure.

General anesthesia for ERCP is performed in much the same fashion as for any other procedure, except that endotracheal intubation is mandatory. It is essential to carefully secure the endotracheal tube since both the patient’s position and the passage of the endoscope will increase the chances of the tracheal tube being dislodged. Induction and maintenance of anesthesia can be achieved with any number of medications, but once again, propofol is ideal because of the rapid recovery it facilitates. Careful positioning and adequate padding are as important as with deep sedation. In contrast to deep sedation, however, the problems of hypoventilation and aspiration during general anesthesia are negligible. It is for this reason that some practitioners choose general anesthesia exclusively for ERCP.

At the end of the procedure, the patient should be taken to the recovery area where monitoring can continue until the patient’s mental status returns to baseline level. The patient is at particular risk for oversedation immediately following the cessation of the procedure and transport to the recovery room, since there is an abrupt end to stimulation while sedation has only begun to wane. If sedatives other than propofol are used during the ERCP, close attention to the half lives of those drugs is important to avoid recrudescence of their effects. Optimally, a patient should not be released from the recovery area until his or her condition is assessed by the operating physician and found to meet acceptable recovery criteria. If benzodiazepine or opioid antagonists (flumazenil, naloxone) are used to facilitate recovery, these agents’ duration of action may be shorter than that of the benzodiazepine or opioid. Thus, the possibility of sedation or hypoventilation should be kept in mind.

Availability of Emergency Equipment

The ready availability of appropriately sized emergency equipment reduces the risk of morbidity with moderate and deep sedation. Although there are no requirements regarding the need for cardiac defibrillators, during moderate sedation a defibrillator should be immediately available for patients with both mild (e.g., hypertension) and severe (e.g., ischemia, congestive failure) cardiovascular disease.

During deep sedation, a defibrillator should be available immediately for all patients. Pharmacologic antagonists, as well as appropriately sized equipment for establishing a patent airway and providing positive pressure ventilation with supplemental oxygen, should be present whenever sedation/ analgesia is administered. Suction, resuscitation medications, and advanced airway equipment should be available immediately and in good working order,23 while the ability to place the patient in head-down (Trendelenburg) position should be present. Considerations for recovery from general anesthesia should not be significantly different than recovery from deep sedation. All the same precautions should be taken to prevent complications. Depending on the anesthetics chosen, it may require longer for the patient to return to their baseline mental status, and the incidence of postoperative nausea and vomiting may be increased over that seen with deep sedation. Both of these factors can be problematic in the outpatient environment and should be considered when choosing general anesthesia as the anesthetic technique.

Conclusion

Successful anesthesia for ERCP depends primarily upon recognizing the special problems presented by the procedure, the patient’s health status and comorbidities, the positioning during the procedure, and the availability of appropriate equipment and personnel. The environment, positioning, and patient population for ERCP will affect the choices that can be made for the conduct of anesthesia. Deep sedation or general anesthesia are acceptable options if the anesthesia care provider is careful to optimize the anesthetic facilities, assess the patient’s susceptibility to airway compromise, and evaluate each patient with safety as the primary focus. The national shortage of anesthesiologists and certified nurse anesthetists is reaching critical levels,24 and manpower projections are not optimistic for at least a decade. Because of this paucity of available personnel, other physicians with specific training and expertise in moderate and deep sedation will need institutional credentialing to ensure efficient, effective, and safe patient care.

References

1. Joint Commission on Accreditation of Healthcare Organizations. Care of Patients (TX): Standards, Intent Statements, and Examples for Sedation and Anesthesia Care. Comprehensive Accreditation Manual for Hospitals (CAMH): The Official Handbook. Oakbrook Terrace, IL: Joint Commission Resources; August 2000.

2. American Society of Anesthesiologists. Guidelines for Ambulatory Anesthesia and Surgery: 2001 Manual for Anesthesia Department Organization and Management (Section 5-4). Park Ridge, IL; 2001.

3. American Society of Anesthesiologists. Standards for Basic Anesthetic Monitoring: 2001 Manual for Anesthesia Department Organization and Management (Section 3-5). Park Ridge, IL; 2001.

4. American Society of Anesthesiologists. Guidelines for Office-Based Anesthesia: 2001 Manual for Anesthesia Department Organization and Management (Section 5-5). Park Ridge, IL; 2001.

5. American Society of Anesthesiologists. Guidelines for Nonoperating Room Anesthetizing Locations: 2001 Manual for Anesthesia Department Organization and Management (Section 3-12). Park Ridge, IL; 2001.

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18. Gillham MJ, Hutchinson RC, Carter R, et al. Patient-maintained sedation for ERCP with a target-controlled infusion of propofol: A pilot study. Gastrointest Endosc 2001; 54:14-17.

19. Wong RC. The menu of endoscopic sedation: All-you-can-eat, combination set, a la carte, alternative cuisine, or go hungry. Gastrointest Endosc 2001; 54:122-126.

20. Sobel RM, Morgan BW, Murphy M. Ketamine in the ED: Medical politics versus patient care. Am J Emerg Med 1999; 17:722-725.

21. Seifert H, Schmitt TH, Gultekin T, et al. Sedation with propofol plus midazolam versus propofol alone for interventional endoscopic procedures: a prospective, randomized study. Aliment Pharmacol thera 2000; 14:1,207-1,214.

22. Wille RT, Barnett JL, Chey WD, et al. Routine droperidol pre-medication improves sedation for ERCP. Gastrointest Endosc 2000; 52:362-366.

23. Stone DJ, Gal TJ. "Airway Management." In: Anesthesia, 5th Ed. Philadelphia: Churchill Livingstone; 2000. Chapter 39.

24. Schubert A, Eckhout G, Cooperider T, et al. Evidence of a current and lasting national anesthesia personnel shortfall: Scope and implications. Mayo Clin Proc 2001; 76:995-1,010.