Key points

Introduction

The role of the anesthesia service in sedation for gastrointestinal endoscopy (GIE) has been steadily increasing. The goals of preprocedural assessment for GIE are determined by the specific details of the procedure, the issues related to the illness that requires the endoscopy, comorbidities, the goals for sedation, and the risk of complications from the sedation and the endoscopic procedure. Rather than consider these issues as separate entities, they should be considered as part of a continuum of preparation for GIE. This is told from the perspective of an anesthesiologist who regularly participates in the full range of sedation for the full spectrum of GIE.

Introduction

The role of the anesthesia service in sedation for gastrointestinal endoscopy (GIE) has been steadily increasing. The goals of preprocedural assessment for GIE are determined by the specific details of the procedure, the issues related to the illness that requires the endoscopy, comorbidities, the goals for sedation, and the risk of complications from the sedation and the endoscopic procedure. Rather than consider these issues as separate entities, they should be considered as part of a continuum of preparation for GIE. This is told from the perspective of an anesthesiologist who regularly participates in the full range of sedation for the full spectrum of GIE.

The anesthesia approach to preparation for a procedure

Because any anesthesia case can evolve in complexity, preparation focuses on the needs for the most complex. The starting point is a traditional history and physical (H&P) examination, with all additional interventions driven by the results. The age and weight are the context, but do not dictate any specific testing. The present illness dictates further preparation, when there are interventions that delineate diminished functional capacity, or by virtue of events, such as hemorrhage. The comorbidities are identified in the context of how the disease influences functional reserves of major organs. The physical examination is targeted to the heart, lungs, central nervous system, and gastrointestinal (GI) tract with special attention to the airway. The penultimate element of preparation is the use of all of these elements to create a plan for the anesthetic intervention. For GIE, this would range from mild sedation to general anesthesia (GA). The plan requires realistic descriptions to the patient of the options for sedation and informed consent. For upper endoscopy, the invasiveness of upper endoscopy intubation requires either a cooperative or unconscious patient. This is a key element of the plan as well as consent.

Contrast between the endoscopy suite and the operating room

In the operating room (OR), the surgeon is the primary care physician (PCP) for the patient, and directly or indirectly responsible for all elements of preparation, even those delegated to the anesthesia team. In contrast, many endoscopy suites are often open units, and the endoscopist is rarely the PCP. In the absence of protocols, many elements of preparation can be variable in this setting. Even the basic H&P and preprocedural instructions may not occur without specific unit protocol. Preparation is limited to those measures that prepare the patient for endoscopy with little attention to preparation for an anesthetic intervention. On the other hand, the conditions during endoscopy are different from surgery, where immobility, total anesthesia, and complete analgesic are assumed. During endoscopy with conscious sedation, some movement is the rule rather than the exception, and the discussion of approaches to sedation reflects this set point for both the patient and the endoscopist. Also, procedural amnesia is not always required during some GIEs. Inadequate preparation by the referring PCP that necessitates cancelling the case requires education of the PCP as to the needs for proper preparation to facilitate safe sedation for GIE.

Gastrointestinal endoscopy procedures

Most GEI procedures (GIEPs) are esophagogastroduodenoscopy (EGD) or colonoscopy for diagnoses of benign conditions or cancer screening for healthy, ambulatory patients. The sedation needs are limited and the preparation is mainly determined by the needs of the endoscopy procedure. Physical preparation of the patient is the responsibility of the PCP or the physician ordering the endoscopy. Laboratory testing is unusual and nothing by mouth (NPO) intervals are short, accommodating the needs of the intestinal preparation, especially for colonoscopy. When a GIEP requires deep sedation or GA, this level of preparation may be inadequate. Participation or direction by the anesthesia team may improve efficiency of the endoscopy suite.

With repeat procedures, the outcome of previous sedation can dictate the degree of preparation required. When the procedure is brief, the sedation minimal, and the patient satisfaction with the previous procedure high, minimal preparation is again reasonable. When the outcome is otherwise, deeper sedation may be necessary and more involved preparation and longer NPO intervals may be required. When the next procedure is more involved, such as endoscopic ultrasound (EUS) or endoscopic retrograde cholangiopancreatography (ERCP), the depth of sedation needed is deeper. The need for preparation is greater as is the need to inform the patient of the need for deeper sedation. If deep sedation or GA is required, the patient must be clearly informed of the correct NPO interval, especially if bowel preparation is required.

The gastrointestinal illnesses that requires endoscopy

An increasing number of patients require these routine GIEs for various chronic GI diseases, such as Crohn disease, Barrett esophagus, or ulcerative colitis, and may require sedation administered by an anesthesia team for patient comfort or safety. These patients may need to be prepared in a manner analogous to the process used before ambulatory surgery. A subset of these patients will require formal GA for which preparation is directed by the need for GA.

When GI bleeding is involved, preparation is directed toward anemia. With chronic anemia, the minimum hemoglobin level allowable for deep sedation or GA is considered to be approximately 8 g/dL. In the setting of acute GI bleeding with deep endoscopy (double-balloon, single-balloon, or spiral endoscopy), deep sedation or GA may be required. Acute hemorrhage in the face of myocardial or cerebral ischemia may require higher hemoglobin levels for sedation. The availability of blood is best determined by a type and screen that could identify any problems, such as the presence of antibodies. This could adversely affect quick availability of blood products.

Altered gastrointestinal motility

When GI mobility is decreased, preparation for sedation is dictated by the risk of aspiration. With gastroparesis or achalasia, dietary restrictions may need to be extended and NPO intervals for liquids 8 hours or greater. With gastric outlet obstruction, the potential full stomach may require GA with endotracheal intubation. This is also true with anticipated tight esophageal stricture, where residual liquid or solid may be encountered. Preparation may extend to the approach to upper endoscopy, with a small endoscope and topical anesthesia allowing entry to the esophagus and stomach. If empty, the procedure proceeds. If high liquid gastric or esophageal residual is encountered, one of the choices is to empty the liquid with endoscopic suction and proceed. If excessive liquid or solid residual is encountered, the endoscope is withdrawn and either intubation of the trachea to protect from aspiration or terminate the procedure and reschedule after a longer liquid diet regimen are the options. Although clear liquids have the fastest transit time, and all colonoscopy preparation solutions are clear liquids, their large volumes can affect the residual left in the stomach if they are consumed right before the procedure and increase the risk of regurgitation, which could cause aspiration.

Infection

When the indication for the endoscopy is infection (abscess, cholangitis), the goal of preparation for sedation is to determine if the patient is hemodynamically stable. Signs of sepsis include fever, hypotension, and tachycardia. Laboratory investigation should focus on identification of leukocytosis and metabolic acidosis. Optimization requires antibiotic administration and correction of intravascular volume deficits, as hypovolemia can cause hemodynamic instability during sedation.

Biliary and pancreatic diseases

Most of the endoscopy procedures involving the biliary tract require advanced endoscopic techniques, such as ERCP or EUS with deep sedation, which dictates preparation for anesthesia delivered service. Procedures that involve common duct obstructions can be associated with cholangitis with liberation of purulent material into the proximal upper GI tract and may require general endotracheal anesthesia (GETA). Copious stones in the ductal system may require high-volume irrigation, which creates the potential for regurgitation of liquid that exceeds the performance of endoscopic suction with the potential of pulmonary aspiration, also requiring GETA. Drainage of large pancreatic cysts also may overwhelm endoscopic suction, with the potential for infected pulmonary aspiration, another indication of GETA. EUS-guided biopsy of the pancreas may be more successful with anesthesia-directed deep sedation.