Anaesthetic considerations during endoscopic retrograde cholangiopancreatography.
Endoscopic retrograde cholangiopancreatography has evolved from being a simple diagnostic procedure, performed under proceduralist-administered sedation, to a therapeutic one involving increasingly complex techniques that require a high degree of patient cooperation. The anaesthetist has become a vital member of the team. Many of the patients are medically unfit for surgery. Sedation or general anaesthesia is generally indicated for the increasingly complex, long and painful procedures being performed. Although there is very little published evidence of specific anaesthetic techniques in this area, knowledge of these problems allows the anaesthetist to select an appropriate technique to provide safe and effective anaesthesia.
Key Words: endoscopic retrograde cholangiopancreatography, endoscopy, anaesthesia, conscious sedation
Using the key terms anaesthesia, endoscopic retrograde cholangiopancreatography, endoscopy, conscious sedation and combinations of these, a Medline, Cochrane Library and National Library of Medicine PubMed (http://www.ncbi.nlm.nih.gov) search of publications identified over 200 original papers and reviews. Of these, information was extracted from 41 studies which illustrated the evolution of the modern practice of ERCP and the issues of relevance to anaesthetic practice. The bibliographies of included studies were also scanned for additional references.
ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY
Endoscopic cannulation of the major papilla with imaging of the pancreatic duct and biliary tree was first reported in 1968 (1). Since then, rapid advances in endoscopic technology have led to dramatic changes in the diagnosis and treatment of biliopancreatic disease and endoscopic retrograde cholangiopancreatography (ERCP) has evolved from being a simple diagnostic procedure to a therapeutic one of increasing length and complexity.
Less invasive imaging techniques, such as endoscopic ultrasound, and magnetic resonance cholangiopancreatography have become more widely utilized to the extent that ERCP should now be reserved for patients in whom a therapeutic intervention is likely. A prospective single centre study (2) of 1223 ERCPs (45.3% diagnostic, 54.7% therapeutic) focused on post-ERCP complications and on identifying risk factors for acute pancreatitis after diagnostic and therapeutic ERCP. The overall complication rate was 11.2% (7.2% pancreatitis, 0.8% bleeding, 0.7% fever, 0.25% cholecystitis, 0.08% perforation and 1.5% other). Pancreatitis was mild in 68% of cases, moderate in 25% and severe in 7%. Two patients died due to severe pancreatitis.
However, the spectrum of therapeutic applications of ERCP continues to expand, enabling treatment of more complex biliopancreatic disease. The requirement for open surgical and percutaneous techniques has diminished and almost all biliary diseases are now amenable to endoscopic treatment. As a result of this, many patients who were previously considered to be inoperable or with life-threatening conditions are presenting for therapeutic ERCP The anaesthetist is increasingly called on to provide either sedation or general anaesthesia in the radiology department. The anaesthetic management of these patients requires a good understanding of both the pathophysiology of the disease and the endoscopic procedure. The aim of this article is to elucidate this expanding field and provide an overview of the anaesthetic issues.
BILE DUCT CANNULATION
After cannulation of the duodenal papilla, the catheter tip is orientated towards the bile duct and contrast media is injected with continuous fluoroscopic monitoring to define the biliary duct system. New devices are constantly being developed to improve the success rate of cannulation, such as a new steerable catheter resulting in successful cholangiography in over 95% of cases (3). Glucagon or hyoscine-N-butylbromide (Buscopan) are often used to inhibit duodenal motility and enhance cannulation during ERCP. Glucagon may elicit hyperglycaemia whereas Buscopan manifests an anticholinergic effect but there appears to be no difference between the two with regard to success rate for cholangiopancreatography (4,5).
BILIARY SPHINCTEROTOMY AND PRECUT PROCEDURES
Endoscopic sphincterotomy of the bile duct is commonly performed prior to removing bile duct stones or placing a biliary stent. Minor bleeding may occur but usually stops spontaneously. This is relatively contraindicated in patients with a known coagulopathy who are anticoagulated or on antiplatelet drugs. A prospective study of 250 patients undergoing endoscopic biliary sphincterotomy for common bile duct stones demonstrated an overall complication rate of 8.4%, with bleeding in 2.8% of cases and 4.8% developing pancreatitis (6).
BILE DUCT STONES
Balloon catheters and retrieval baskets are used for extracting stones. In experienced hands, common duct stones can be successfully removed in 80-90% of patients after sphincterotomy using standard baskets and balloon catheters (7).
A variety of lithotripsy and dissolution therapies have been used to facilitate the retrieval of stones not removable by standard methods (8). When stone extraction is incomplete or failed, biliary drainage should be established to prevent stone impaction and cholangitis. In most situations, this serves as a temporary measure allowing for improvement in the patient's clinical condition pending repeat attempts at stone removal.
Biliary drainage procedures are indicated for a variety of conditions, including benign biliary strictures occurring after cholecystectomy, distal common bile duct strictures secondary to chronic pancreatitis, primary sclerosing cholangitis and malignancies. The indications for considering endoscopic management in these conditions are the treatment of jaundice, pruritus, symptomatic cholangitis, deteriorating hepatic function and if suspicion of bile duct cancer is high. Acute suppurative cholangitis due to common bile duct stones is a life-threatening condition that requires immediate biliary drainage; endoscopic biliary drainage is associated with a lower morbidity and mortality rate than surgery in this setting (9). The techniques that may be utilized to achieve this goal are endoscopic sphincterotomy and placement of stents or nasobiliary tubes.
Progress in therapeutic biliary endoscopy is currently focusing on identifying the best treatment options to be used in each case in relation to the available evidence (10). The same techniques and instruments used to treat biliary tract disease have been adapted for use in the pancreatic duct. The aim of these therapies is to alleviate the obstruction to exocrine juice outflow in such conditions as chronic pancreatitis, pancreatic strictures and pancreatic duct stones.
The safety of ERCP is dependent upon the medical condition of the patient undergoing the procedure. The importance of familiarity with the patient's medical history prior to a procedure is paramount; many of these patients present with jaundice, gallstone pancreatitis, acute cholangitis, malignant biliary strictures or pancreatic cancer, which may be associated with ascites or pleural effusions. In general this group of patients are sicker than those undergoing upper gastrointestinal endoscopy and require full pre-operative assessment in accordance with guidelines published by the Australian and New Zealand College of Anaesthetists (ANZCA) (11). However, because they are admitted under physicians, they often appear on a list without having been to a pre-assessment clinic or may be in-patients on a ward.
Patients presenting for this procedure may have a history of hepatic dysfunction with associated coagulopathy and metabolic disturbances. Haemodynamic stabilization and protection against pulmonary aspiration are important in all patients, but particularly those who are septic. In those with severe ascites, ventilation may be impaired by the elevation of the diaphragm and the resulting raised intra-abdominal pressure. Large volumes of gas may be used during the procedure and this can lead to respiratory difficulties in patients with impaired respiratory function. In our institution, 46% of those who present for ERCP are American Society of Anesthesiologists physical status 3-5.
Preparation for ERCP involves assembly of a skilled team that includes physicians, nursing personnel, anaesthetic support and a radiology technician. A quality fluoroscopic unit is needed, which is usually located in the radiology suite, without immediate access to the operating department and its coexisting benefits. The provision of safe anaesthesia outside the operating suite requires appropriate staff, facilities and equipment in accordance with ANZCA guidelines (12). In common with other radiological procedures, the anaesthetist is working in a darkened room with limited access to the patient, who is on a radiology table that does not readily tilt. The procedure room is usually cluttered with large pieces of fixed equipment and several staff members. Cardiopulmonary resuscitation can be difficult in this crowded environment.
Patient monitoring should include pulse oximetry, ECG, capnography and blood pressure recording, which on occasion should be intra-arterial depending on the patient's condition.
An appropriately staffed and equipped recovery area should be available until patients return to their pre-sedation state of consciousness and cardiopulmonary function. However this is not always available in the radiology suite and the anaesthetist may find himself or herself recovering the patients until they can safely return to the ward.
In order to facilitate the performance of complex therapeutic ERCP, conscious sedation has become standard practice in most developed countries, especially because patient cooperation is necessary for successful completion of interventional biliopancreatic procedures (13,14).
Sedation includes the administration by any route or technique of all forms of drugs that result in depression of the central nervous system, in order to produce a degree of sedation, without loss of consciousness, so that uncomfortable diagnostic and surgical procedures may be facilitated (15).
The drugs and techniques used should provide a margin of safety that is wide enough to render loss of consciousness unlikely, as loss of consciousness due to sedation has the same risks as general anaesthesia". Excessive sedation may result in cardiac or respiratory depression and depression of protective airway reflexes. Conversely, inadequate sedation may result in patient discomfort or even injury because of lack of cooperation or adverse physiological response to stress.
The ideal goal is a medically controlled state of depressed consciousness which allows protective reflexes to be maintained, retains the patient's ability to maintain a patent airway independently and continuously and permits appropriate response by the patient to physical stimulation or verbal commands (16,17).
However, in contrast to upper gastrointestinal endoscopy, patients undergoing therapeutic ERCP are often subjected to long and uncomfortable procedures that require them to keep absolutely still in order to facilitate a difficult intervention requiring precision from the endoscopist. Any movement by the patient can have considerable effect on the success of the technique. It may be difficult for conscious sedation alone to fulfil these requirements.
Gastrointestinal endoscopists have traditionally provided sedation whilst simultaneously performing ERCE Providing safe and adequate sedation may occasionally be as challenging as the technical aspects of the procedure itself. It is not infrequent to find patients fulfilling the criteria for deep sedation in order to facilitate acceptance of the procedure.
Furthermore, moving from a state of consciousness to deep sedation is a dose-related continuum that depends on patient response and the state originally intended might not be the one ultimately achieved. There is wide variability in the pharmacokinetics and pharmacodynamics of sedative drugs; thus a 'standard' dose of sedatives may produce undersedation in some patients and substantial oversedation resulting in anaesthesia in others (18,19). Indeed, physicians' and nurses' assessments of patient satisfaction with sedation for endoscopic procedures correlate poorly with the patients' own assessments (20).
Although endoscopy under sedation is generally regarded as safe, there are few prospective data regarding cardiopulmonary complications. One large multicentre study from North America demonstrated that the leading cause of death from ERCP and sphincterotomy were cardiopulmonary complications (21); and in a large audit of upper endoscopy from the U.K., cardiopulmonary complications resulted in mortality in 1 in 2000 procedures (22). The cardiopulmonary mortality of endoscopy likely exceeds that of general anaesthesia (20,23). Sedation-related complications were attributed to high doses of benzodiazepines combined with opioids and a lack of adequate monitoring. Subsequently, recommendations for minimum standards of monitoring and supplementary oxygen were introduced (24,25,26) and an increased awareness of the appropriate dosage of benzodiazepines and opioids followed.
Nonetheless, during upper gastrointestinal endoscopy, ST segment changes have been found in a significant number of healthy patients: a recent study from Northern Ireland of 41 patients undergoing ERCP with gastroenterologist-administered sedation, found that nine patients (22%) experienced ST depression during the procedure, of whom four (10%) showed significant ST depression ([greater than or equal to]2 mm), only one of whom had a previous cardiac history (27). There were no adverse cardiovascular events noted and the clinical significance of myocardial ischaemia in healthy patients is unknown; however, experimental studies suggest that repeated episodes of ischaemia may have a cumulative adverse effect and may eventually lead to myocardial infarction (28).
Christensen and co-workers evaluated changes in myocardial blood flow in ten patients with no previous cardiac history undergoing ERCP (29). Myocardial perfusion was evaluated using Holter monitoring and perfusion scintigraphy, performed at rest and during and after ERCE Two patients developed signs of ischaemia on both Holter recording and on myocardial scintigraphy.
The risk of myocardial ischaemia appears to be higher for ERCP than for either gastroscopy or colonoscopy (30). The mechanisms for this probably relate to tachycardia, associated with the greater stress response, or hypoxaemia. Further confirmatory studies in these areas are required to determine the precise incidence and mechanism. Assessment of patients by means of troponin, creatine kinase measurements or by exercise stress testing would have provided useful additional information as to the significance of the observed myocardial ischaemia.
In the light of these developments, it is becoming increasingly common for anaesthetists to give sedation, monitor patients, or even administer general anaesthesia for ERCP where indicated. Debate continues over the ideal sedative agent and the ideal dosage regimen.
There are numerous studies demonstrating the equivalency of benzodiazepines with respect to safety (31-34). ". Propofol has been evaluated in the endoscopy suite in a variety of regimens (35-37) and has been shown to provide the same or superior sedation quality as midazolam with the advantage of a shorter recovery time (38,39). The Australian and New Zealand College of Anaesthetists does not condone the administration of intravenous anaesthetic agents such as propofol by non-anaesthetists.
Although the majority of endoscopic procedures are successful under conscious sedation, therapeutic ERCP usually requires deep sedation or general anaesthesia. Patients often need to be unconscious to tolerate this procedure and therefore an anaesthetist needs to be present (40,41). General anaesthesia has historically been provided during ERCP only when prior attempts using conscious sedation have failed. With the development of newer, more advanced endoscopic techniques, it is now more frequently indicated.
General anaesthesia is generally regarded as being a continuum in which increasing depth of anaesthesia results in loss of consciousness, loss of recall and reflexes, in particular, loss of protective airway reflexes. During anaesthesia for ERCP, patients are either intubated with an endotracheal tube, or spontaneously breathe oxygen via nasal prongs with an unprotected airway, depending on their comorbidities and fasting status. However, one group from New York looked at the feasibility of using the laryngeal mask airway during ERCP (42). Of 40 patients undergoing ERCP, 20 were managed with a laryngeal mask airway versus 21 with an endotracheal tube. Laryngeal mask airway use was associated with shorter extubation time compared with endotracheal intubation (7.2 vs 12 minutes) and there were no airway complications. A therapeutic duodenoscope was passed beyond the LMA with little or no resistance in all cases.
The risk of aspiration in the patient who is under general anaesthesia with an unprotected airway must be considered on an individual basis depending on the preoperative assessment and the duration and complexity of the procedure. The practitioner must also be able to detect and manage appropriately any complications arising from this technique. The semiprone position facilitates this, but good communication with the proceduralist and close attention to the patient's airway are required at all times during the procedure.
The indications for general anaesthesia are also related to the type of procedure planned. A large retrospective analysis from Germany found that painful dilatations were performed more frequently with patients under general anaesthesia, and that under conscious sedation, the ERCP failure rate was double that with general anaesthesia (43).
In another large study from U.S.A. (44) it was noted that the overall complication rate associated with therapeutic interventions during ERCP was significantly lower in patients who had received a general anaesthetic than those who had undergone conscious sedation. It was thought that less patient movement and duodenal aperistalsis related to general anaesthesia may have made procedures technically easier and might have contributed to the low complication rate.
Despite this, ERCP under general anaesthesia has several limitations. The procedure is often prolonged as a result of extra time required for patient preparation, induction of anaesthesia and tracheal intubation. In addition, the cost per procedure may be higher. However, the efficacy of ERCP with general anaesthesia supports a continued preference for general anaesthesia rather than conscious sedation when complex and painful interventional ERCP procedures are planned.
Enormous progress has been made in techniques of therapeutic biliary endoscopy, which has contributed to the rapid expansion of this field and the improving success rate of procedures. Gastroenterologists have recognized the need for anaesthetists in therapeutic ERCP, but there is a lack of data in the anaesthetic literature regarding techniques and potential pitfalls. It is hoped that increasing understanding and awareness of this evolving field will stimulate further research, especially with regard to morbidity resulting from cardiopulmonary complications.
Accepted for publication on May 9, 2006.
(1.) McCune WS, Shorb PE, Moscovitz H. Endoscopic cannulation of the ampulla of vater: a preliminary report. Ann Surg 1968; 167:752-6.
(2.) Vandervoort J, Soetikno MR, Tham TCK et al. Risk factors for complications after performance of ERCP Gastrointest Endosc 2002; 56:652-656.
(3.) Igarashi Y, Tada T, Shimura J et al. A new cannula with a flexible tip (swing tip) may improve success rate of endoscopic retrograde cholangiopancreatography. Endoscopy 2002; 34:628-631.
(4.) Chang FY, Guo WS, Liao TM, Lee SD. A randomized study comparing glucagon and hyoscine N-butyl bromide before endoscopic retrograde cholangiopancreatography. Scand J Gastroenterol 1995; 30:283-286.
(5.) Lahoti S, Catalano M, Geenen J, Hogan WJ. A prospective, double-blind trial of L-hyoscyamine versus glucagon for the inhibition of small intestinal motility during ERCE Gastrointest Endosc 1997; 46:139-142.
(6.) Mavrogiannis C, Liatsos C, Papanikolaou IS et al. Safety of extension of a previous endoscopic sphincterotomy: a prospective study. Am J Gastroenterol 2003; 98:72-76.
(7.) Foutch PG. Endoscopic management of large common duct stones. Am J Gastroenterol 1991; 86:1561.
(8.) Graham SM, Flowers JL, Zucker KA. Endoscopic management of the difficult common bile duct stone. Surg Laparosc Endosc 1993; 3:54-9.
(9.) Leese T, Neoptolemos J, Baker A, Carr-Locke D. The management of acute cholangitis and the impact of endoscopic sphincterotomy. Br J Surg 1986; 73:988-92.
(10.) Mutignani M, Tringali A, Costamagna G. Therapeutic biliary endoscopy. Endoscopy 2004; 36:147-159.
(11.) Recommendations on the Pre-Anaesthetic Consultation. PS7 ANZCA.
(12.) Recommendations on minimum facilities for safe anaesthesia practice outside operating suites. T2 (2000) ANZCA.
(13.) Daneshmed TK, Bell GD, Logan RE Sedation for upper gastrointestinal endoscopy: results of a nationwide survey. Gut 1991; 32:12-15.
(14.) Keeffe EB, O'Connor AW 1989 A S G E survey of endoscopic sedation and monitoring practices. Gastrointest Endosc 1990; 36:S13-18.
(15.) Guidelines on conscious sedation for diagnostic, interventional medical and surgical procedures. PS9 (2001) ANZCA.
(16.) Epstein B. Physiology of the sedated patient: how to properly monitor. In: Conscious sedation, its reversal and monitoring in gastrointestinal endoscopy: a clinical symposium. San Francisco: American Society for Gastrointestinal Endoscopy, May, 1992.
(17.) Joint Commission on Accreditation of Healthcare Organisations. Comprehensive accreditation manual for hospitals: the official handbook. January 1997.
(18.) Cousins MJ. Monitoring--the anaesthetist's view. Scand J Gastroenterol Suppl 1990; 179:12-17.
(19.) Gourlay G, Kowalski S, Plummer J et al. Fentanyl blood concentration--analgesic response relationship in the treatment of postoperative pain. Anesth Analg 1988; 67:329-337.
(20.) Jowell P, Eisen G, Onken J, Bute BP, Ginsberg B. Patient-controlled analgesia for conscious sedation during endoscopic retrograde cholangiopancreatography: a randomized, controlled trial. Gastrointest Endosc 1996; 43:490-494.
(21.) Freeman ML, Nelson DB, Sherman S et al. Complications of endoscopic biliary sphincterotomy. N Engl J Med 1996; 335:909-918.
(22.) Quine MA, Bell GD, McCloy RF et al. Prospective audit of upper gastrointestinal endoscopy in two regions of England: safety, staffing and sedation methods. Gut 1995; 36:462-467.
(23.) McCloy R. Asleep on the job: sedation and monitoring during endoscopy. Scand J Gastroenterol Suppl 1992; 192:97-101.
(24.) Standards of Practice Committee. American Society for Gastrointestinal Endoscopy. Monitoring of patients undergoing gastrointestinal endoscopic procedures. Guidelines for clinical application. Gastrointest Endosc 1991; 37:120-121.
(25.) Bell G, McCloy R, Charlton J et al. Recommendations for standards of sedation and patient monitoring during gastrointestinal endoscopy. Gut 1991; 32:823-827.
(26.) Practice guidelines for sedation and analgesia by non-anesthesiologists. A report by the American Society of Anesthesiologists Task Force on Sedation and Analgesia by non anesthesiologists. Anesthesiology 1996; 84:459-471.
(27.) Johnston SD, McKenna A, Tham TCK. Silent Myocardial Ischaemia during Endoscopic Retrograde Cholangiopancreato graphy. Endoscopy 2003; 35:1039-1042.
(28.) Geft JL, Fishbein MC, Ninomiya K et al. Intermittent brief periods of ischaemia have a cumulative effect and may cause myocardial necrosis. Circulation 1982; 66:1150-1153.
(29.) Christensen M, Hendel HW, Rasmussen V et al. ERCP causes reduced myocardial blood flow. Endoscopy 2002; 34:797-800.
(30.) Thorton J, Axon A. Towards safer endoscopic retrograde cholangiopancreatography. Gut 1993; 34:721-724.
(31.) Bell GD, Morden A, Coady T, Lee J, Logan RFA. A comparison of diazepam and midazolam as endoscopy premedication assessing changes in ventilation and oxygen saturation. Br J Clin Pharmacol 1988; 36:595-600.
(32.) Arrowsmith JB, Gertsman BB, Fleischer DE, Benjamin SB. Results from the American Society for Gastrointestinal Endoscopy/US Food and Drug Administration collaborative study on complication rates and drug use during gastrointestinal endoscopy.
(33.) Daneshmend TK, Bell GD, Logan RFA. Sedation for upper gastrointestinal endoscopy: results of a nationwide survey. Gut 1991; 32:12-15.
(34.) Power SJ, Morgan M, Chakrabarti MK. Carbon dioxide response curves following midazolam and diazepam. Br J Anaesth 1983; 55:837-841.
(35.) Patterson K, Casey P, Murray J, O'Boyle CA, Cunningham AJ. Propofol sedation for outpatient upper gastrointestinal endoscopy: comparison with midazolam. Br J Anaesth 1991; 67:108-111.
(36.) Carlsson U, Grattidge P Sedation for upper gastrointestinal endoscopy: a comparative study of propofol and midazolam. Endoscopy 1995; 27:240-243.
(37.) Oei-Lim V, Kalkman C, Bartelsman J et al. Cardiovascular responses, arterial oxygen saturation and plasma catecholamine concentration during upper gastrointestinal endoscopy using conscious sedation with midazolam or propofol. Eur J Anaesthesiol 1998; 15:535-543.
(38.) Wehrmann T, Kokabpick S, Lembcke B, Caspary WF, Seifert H. Efficacy and safety of intravenous propofol sedation during routine ERCP: a prospective, controlled study. Gastrointest Endosc 1999; 49:677-683.
(39.) Krugliak P, Ziff B, Rusabrov Y, Rosenthal A, Fich A, Gurman GM. Propofol versus midazolam for conscious sedation guided by processed EEG during endoscopic retrograde cholangiopancreatography: A prospective, randomized, double-blind study. Endoscopy 2000; 32:677-682.
(40.) Statement on Credentialling in Anaesthesia PS2 (2001) ANZCA.
(41.) Statement on standards of Practice of a Specialist Anaesthetist PS16 (2001) ANZCA.
(42.) Osborn IP, Cohen J, Soper RJ, Roth LA. Laryngeal mask airway--a novel method of airway protection during ERCP: comparison with endotracheal intubation. Gastrointest Endosc 2002; 56:122-128.
(43.) Raymondos K, Panning B, Bachem I et al. Evaluation of endoscopic retrograde cholangiopancreatography under conscious sedation and general anesthesia. Endoscopy 2002; 34:721-726.
(44.) Etzkorn KP, Diab F, Brown R et al. Endoscopic retrograde cholangiopancreatography under general anesthesia: indications and results. Gastrointest Endosc 1998; 47:363-367.
S. J. MARTINDALE *
Department of Anaesthesia, Sir Charles Gairdner Hospital, Nedlands, Perth, Western Australia, Australia * B.Sc., M.B., B.S., F.R.C.A., L.L.M., Consultant.
Address for reprints: Dr S. J. Martindale, Department of Anaesthesia, Sir Charles Gairdner Hospital, Hospital Ave, Nedlands, Perth, WA. 6009.
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|Publication:||Anaesthesia and Intensive Care|
|Date:||Aug 1, 2006|
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