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Preparation for and Complications of Gastrointestinal Endoscopy
Complications of Newer Endoscopic Techniques
GI endoscopy plays an integral part in the diagnosis and management of a variety of GI ailments. Risks and benefits are inherent to the performance of any procedure. In recent years, the “scope” of GI endoscopy keeps expanding to include procedures such as peroral endoscopic myotomy (POEM), endoscopic submucosal dissection (ESD) of tumors, and endoscopic bariatric procedures. With such expansion comes the need to understand these risks and weigh them against the potential benefits. The importance of this process cannot be minimized. Complications are inevitable, but strict attention to the appropriate indications for such procedures by incorporating optimal technical and cognitive abilities can minimize complications.
Preparation of the Patient for Endoscopy
History and Physical Examination
A thorough and pertinent medical history should be obtained prior to endoscopy. A careful review of previous endoscopic procedures should also be performed. This should include recognition of any adverse events, the targeted level of sedation, and the patient’s satisfaction with the sedation. A list of current medication usage along with relevant allergies should also be obtained. Use of sedatives, analgesics, and alcohol by the patient can predict the need for larger doses of sedatives and analgesics or the use of monitored anesthesia care. A focused physical examination including the airway, heart, lungs, and abdomen should be performed prior to each endoscopy. Assignment of an American Society of Anesthesiology Physical Status (ASA PS) category ( Table 42.1 ) is strongly encouraged because it has been shown to predict adverse cardiopulmonary events.
TABLE 42.1
ASA PS Classification System Used to Assess Risk of GI Endoscopic Procedures
| ASA PS Category | Pre-Procedure Health Status |
|---|---|
| 1 | Healthy (normal) |
| 2 | Mild systemic disease |
| 3 | Severe systemic disease |
| 4 | Severe systemic disease that is a constant threat to life |
| 5 | Moribund (not expected to survive without the procedure) |
| 6 | Brain death (for organ harvest) |
ASA PS , American Society of Anesthesiologists Physical Status.
Antibiotic Prophylaxis
There are several GI endoscopic procedures in which antibiotic prophylaxis is warranted ( Table 42.2 ). The strongest level of evidence for prophylactic administration of antibiotics is prior to percutaneous endoscopic gastrostomy (PEG) placement to reduce the risk of peristomal cellulitis. Antibiotic prophylaxis has also been recommended in all liver transplant patients undergoing ERCP, but the necessity of antibiotics in such patients has been questioned. Intended or unintended manipulation of sterile pancreatic necrosis or a pancreatic pseudocyst during ERCP or EUS, as well as EUS-guided FNA of cystic structures within and surrounding the GI tract, should receive antibiotic prophylaxis. Patients undergoing ERCP with anticipated incomplete drainage of the biliary tree secondary to extensive PSC or hilar tumors should also receive antibiotic prophylaxis. Of note, not all patients with cardiac valvular conditions, synthetic vascular grafts, and prosthetic joints should receive antibiotic prophylaxis because there are no data demonstrating a clear link between GI procedures and infectious complications or demonstrating that antibiotic prophylaxis prevents infectious complications after endoscopic procedures. When prophylactic antibiotics are given, the choice of antibiotic(s) depends upon the specific GI procedure, clinical scenario, and allergy history of the patient.
TABLE 42.2
Conditions and Procedures Requiring Antibiotic Prophylaxis for Endoscopic Procedures
| Patient Condition | Procedure | Goal of Prophylaxis |
|---|---|---|
| Bile duct obstruction without cholangitis | ERCP with anticipated incomplete biliary drainage | Prevention of cholangitis |
| Sterile pancreatic fluid collections that communicate with the pancreatic duct | ERCP | Prevention of cyst infection |
| Sterile pancreatic fluid collection | Transmural drainage | Prevention of cyst infection |
| Cystic lesions along the GI tract, including the mediastinum | EUS-FNA | Prevention of cyst infection |
| Cirrhosis with acute GI bleeding | All endoscopic procedures | Prevention of infectious complications including SBP |
| Any condition | Percutaneous endoscopic feeding tube placement | Prevention of peristomal infection (cellulitis) |
Management of Anticoagulant and Antiplatelet Drugs
With the advent of newer and novel antiplatelet drugs and anticoagulants, it is important for the practicing gastroenterologist to understand the duration of action such agents to decrease bleeding and thrombotic complications. The management of antithrombotic and antiplatelet drugs should be based on the urgency of the endoscopic procedure and the bleeding risk associated with the procedure if the agent is not discontinued. A good framework is required to classify endoscopic procedures as low versus high risk for bleeding and the underlying disease condition as high versus low risk for a thrombotic complication. The ASGE position statement on the management of antithrombotic agents for patients undergoing GI endoscopy is a useful resource. For example, procedures such as biliary sphincterotomy, EUS with FNA, percutaneous gastrostomy, and polypectomy have increased risks of bleeding in patients being treated with warfarin. In high-risk elective procedures, warfarin should be held so that the INR can return to normal; warfarin can usually be restarted within a week after the procedure. In patients with high-risk conditions such as mechanical heart valves, the use of a low molecular weight heparin “bridge” should be used until 12 hours prior to the endoscopic procedure to minimize the thromboembolic risk.
When antithrombotic therapy is temporary, such as in the treatment of venous thromboembolism, elective GI procedures should be delayed if possible until the anticoagulation is no longer indicated. For procedures such as EGD and colonoscopy with biopsy that carry a low bleeding risk, aspirin, NSAIDs, and clopidogrel may be continued. For procedures with a higher bleeding risk, such as endoscopic sphincterotomy, the decision to continue the antiplatelet agent will relate to the risk of a thromboembolic event.
There are limited data currently on optimal management of patients receiving either anticoagulation with newer drugs that have a shorter half-life than warfarin, such as the direct thrombin inhibitor dabigatran or the direct Xa inhibitor rivaroxaban or receiving antiplatelet therapy with a newer P2Y 12 ADP receptor inhibitor such as ticagrelor.
Informed Consent
Written informed consent should be obtained by the endoscopist before performance of any endoscopic procedure. The process of obtaining informed consent is a legal requirement as well as a basic ethical obligation. It allows the patient to gain a thorough understanding of the proposed procedure including the potential risks involved and possible alternatives and to have all questions answered. The components of the informed consent should include a discussion of the procedure itself, including the risks, benefits, and alternatives. The frequency and severity of complications should also be reviewed.
Sedation
Sedation is used for most endoscopic procedures in order to provide a comfortable and safe milieu for the conduct of the procedure. The majority of ambulatory cases including EGD and colonoscopy are performed by targeting a moderate level of sedation. Typically, a combination of a benzodiazepine and opiate is used, although there has been a growth in the application of propofol-mediated sedation over the past decade. Deep sedation or general anesthesia is usually targeted for advanced endoscopic procedures such as ERCP, EUS, ESD, POEM, etc., and in those patients in whom medications used to target moderate sedation could be problematic. This may potentially include patients using narcotic and/or sedative agents as well as those with significant comorbidities who would be at risk for untoward cardiopulmonary events. Patients with hemodynamic instability or respiratory compromise may also benefit from anesthesia-assisted sedation.
Unplanned cardiopulmonary events such as hypotension and hypoxemia occur in 0.9% of procedures. Risk factors for these events include age, ascending ASA PS category (see Table 42.1 ), inpatient procedures, as well as procedures that are targeted for prolonged deep sedation or general anesthesia, such as ERCP. Respiratory complications include hypoxemia and hypoventilation. In ASA PS 1 and 2 patients undergoing ambulatory endoscopy, risk factors for hypoxemia include BMI, advancing age, and higher doses of narcotic analgesics during the procedure. Use of pulse oximetry allows for early identification of hypoxemia, and routine use of supplemental O 2 can prevent hypoxemia in most cases. Alveolar hypoventilation can be due either to central nervous system depression or to relaxation of the hypopharyngeal muscles. The use of capnography to measure effective CO 2 elimination significantly decreases the occurrence of apnea in patients undergoing colonoscopy, ERCP, and EUS in which deep sedation is used. However, there are currently no data supporting routine use of capnography in subjects undergoing EGD or colonoscopy when targeting moderate sedation.
Hypotension during endoscopy is usually due to medication-induced venodilation in patients who are volume depleted and is usually responsive to IV fluid boluses. A vasovagal reaction is the most common cause of arrhythmias seen during endoscopy. This reaction is usually due to a painful stimulus and can usually be remedied by improving endoscope positioning and reducing bowel distention. Occasionally, intravenous atropine and fluid boluses are required. The use of electrocardiographic monitoring should be considered in patients with a history of cardiac disease, in those over the age of 55 years, and in all cases where deep sedation or general anesthesia is targeted. The endoscopist should be familiar with the pharmacokinetics and adverse effect profiles of all sedative medications they use, including their reversal agents such as flumazenil for benzodiazepines and naloxone for narcotics. Having a posted placard in the endoscopy suite with this information readily accessible is prudent.
In the recovery area, there is a risk of re-sedation once the stimulus of the procedure has been removed. Recovery to baseline vital signs is an important discharge criterion. It should be emphasized that psychomotoric recovery can be delayed even in patients receiving fast-acting agents such as propofol. It is therefore advisable to have the patient accompanied by another individual on discharge and to recommend that the patient not drive or operate machinery until the day following the procedure.
Infections
It has been estimated that the rate of transmission infection via GI endoscopy is 1 per 1.8 million in the USA. Infectious adverse events are a consequence of a failure to follow established reprocessing guidelines for endoscopic devices and accessories, failure to follow sterile technique using sedatives such as propofol, or from the procedure itself. Transient bacteremia is not uncommon during endoscopic procedures, but the infectious sequelae from bacteremia, such as endocarditis or seeding of other sites, is so rare that current recommendations from the American Heart Association and the ASGE recommends antibiotic prophylaxis for only very specific situations (see earlier, Antibiotic Prophylaxis, and Table 42.2 ). Because the GI tract is not sterile, high-level disinfection of endoscopes between uses is deemed to be sufficient for preventing transmission of infectious organisms between patients. This process includes mechanical cleaning of channels and the exterior of the endoscope, followed by soaking in disinfectant solutions such as glutaraldehyde or peracetic acid followed by thorough rinsing and drying of the instruments. The recent outbreak of carbapenem-resistant enterococci infection from duodenoscopes raises the specter of scope designs limitations and the need for meticulous disinfection protocols. One outbreak of hepatitis C was linked to improper sterile technique and the use of a vial of sedative on multiple patients. It should be emphasized that high-level disinfection kills most pathogens that could contaminate endoscopes, including HBV, HCV, and HIV. Although prions, such as the Jakob-Creutzfeldt agent, are not inactivated by high-level disinfection, prions are not found in saliva, intestinal tissue, feces, and blood, and hence are judged by the WHO as being noninfectious for the purposes of infection control.
Electrosurgery
The presence of a cardiac pacemaker or implantable cardiac defibrillator (ICD) requires special consideration because electrocautery performed during an endoscopic procedure can inhibit cardiac pacemaker function and can lead to an inappropriate discharge of a defibrillator. It is therefore prudent to place the grounding pad away from the pacemaker on the patient’s thigh or buttock and to use brief bursts of electrosurgical output. Additionally, utilizing a bipolar platform or, in the case of endoscopic hemostasis, a mechanical or thermal device can minimize risk. In the case of an ICD, electrosurgery can induce an unwarranted activation of the device. Temporary deactivation of the ICD with an external defibrillator, coupled with continuous cardiac monitoring of the patient’s cardiac rhythm, should be used.
It is of extreme importance to understand the operational capabilities of the electrosurgical unit used. This should include understanding the various settings on the device and their correlation with the desired tissue effect. Additionally, the endoscopist should be able to troubleshoot the device, should an error message or a disruption in the circuit be noted.
Timing and Severity of Complications
Endoscopic complications can occur during a procedure or may be delayed. Knowledge of the potential complications is a critical element of the informed consent process (see earlier). Just as important is patient education to allow early recognition of signs and symptoms that may indicate a delayed complication, and availability of a streamlined process for contacting the endoscopist about a potential complication for appropriate management. From a quality-improvement and treatment perspective, it is important to use this standard set of definitions for adverse outcomes, which would include elements of timing, attribution, severity, and ultimate outcome.
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