Читать книгу Successful Training in Gastrointestinal Endoscopy - Группа авторов - Страница 37

Once the endoscope is successfully introduced, the next goal is advancement of the scope to a specific extent, as indicated by the clinical reason for the endoscopy. For upper GI endoscopy, this is usually down to the third stage of the duodenum; for colonoscopy, it would be to the cecum, terminal ileum, or to an anastomosis, for example. Scope navigation is accomplished by a series of maneuvers that include tip deflection, scope rotation/application of torque, external compression of the abdomen, adjusting the patient position, insufflation and suction of air or fluids, and insertion and withdrawal of the scope.

Control of the tip of the endoscope is necessary when navigating to maintain an adequate luminal view, as well as to assist in advancement of the endoscope. Depending on the type of endoscopy being performed, tip control may be done in different ways by nature of the physical characteristics of the endoscopes. Standard esophagogastroduodenoscopy (EGD) (hereafter referred to as EGD, or gastroscopy) requires very different maneuvers than endoscopic retrograde cholangiopancreatography (ERCP) or colonoscopy, for example. In the case of ERCP, the increased endoscope stiffness and oblique viewing angle mandates very different technical skills. Intubation, manipulation of the endoscope tip through the stomach, traversing the pylorus, and positioning in front of the papilla require very different maneuvers and changes in body position than are required for other procedures. It is our preference to train endoscopists to use the left hand to grip the handle of the endoscope and to manipulate the wheels using the thumb of the left hand for all procedures, particularly during colonoscopy. The main advantage of this approach is to reserve the right hand for advancement and withdrawal of the endoscope, and application of torque when necessary. This allows us to focus our trainees’ attention upon the sensation of resistance or torque in their right hand. If additional tip deflection is required, small movements of the wheels using the left thumb is typically sufficient. This awareness of changing resistance, possible impending scope movement/stability or response to torque is particularly important when attempting to perform maneuvers such as shortening the endoscope in ERCP, resolving a loop in colonoscopy, or when performing controlled small repositioning maneuvers in endoscopic ultrasound, for example. It is useful to also train in the use of imaging techniques such as fluoroscopy or scope imaging devices [10] for those situations when the endoscopic image does not provide sufficient information to guide scope navigation. Although some endoscopists prefer to use alternative navigation methods such as controlling tip deflection via two hands on both endoscopy wheels while an assistant advances, rotates, and applies torque to the scope, we feel that this is less than optimal for training purposes for a variety of reasons, particularly for more advanced or difficult endoscopic procedures and maneuvers and techniques.

With appropriate insufflation (of air, water, or carbon dioxide), the lumen of the GI tract can be identified and the scope advanced to the desired limit of examination. Too much insufflation adds to patient discomfort, may precipitate cardiovascular instability, and can increase the risk of perforation or aspiration. Insufflation is required only to achieve sufficient distension of the bowel for an adequate view of the circumference of the bowel wall, to assist in identifying the lumen or differentiating the lumen from a diverticular opening, and to provide adequate focal distance between the lens of the scope and the object being viewed. The endoscopist should also be trained in the use of pharmacological agents that can assist in maintaining stability of position (e.g., in ERCP) or inspection (e.g., screening for early gastric cancer) by decreasing bowel contractions.

The endoscopist should be familiar with the unique endoscopic characteristics of the portion of the GI tract being examined. For example, the sigmoid, descending colon, colonic flexures, transverse colon, and ileocecal region all have specific endoscopic appearances. In most cases, knowledge of these appearances is useful feedback for the endoscopist in knowing where he is within the colon and what strategies need to be used if advancement of the scope is not successful. This is particularly relevant during colonoscopy in which different strategies may be employed in the right versus the left colon. Furthermore, it is important to understand the concept of paradoxical movement. In this situation, the endoscope is being advanced, but its distal tip is retracting as a loop is forming within the bowel. Similarly, the endoscopist should recognize both in the endoscopic image and in the sensation perceived by the right hand when advancement of the endoscope is not producing an associated advancement of the tip of the scope. This can lead to patient discomfort and increase the risk for perforation. At this point, consideration should be given to strategies for dealing with such difficulties. Depending on the type of endoscopy and patient factors (tortuous anatomy, altered anatomy, presence of surgical adhesions, etc.), strategies may vary.

Attention to landmarks within the upper GI tract such as the Z‐line marking the squamocolumnar junction, the location of the hiatus, the various regions of the stomach (cardia vs. fundus, body vs. antrum, lesser curve vs. greater curvature, incisura angularis) should also be considered during upper endoscopic training. In endoscopic ultrasound (EUS) training, knowledge of vascular anatomy forms the linchpin for orientation and imaging of many intrathoracic and intra‐abdominal structures. Without this understanding, it is impossible for the endoscopist to accurately communicate the location of observed pathology.

Some knowledge of surgical anatomy is also essential. The endoscopist should know the implications of an end‐to‐end versus end‐to‐side versus side‐to‐side anastomosis. Without this understanding, it is possible to perforate the bowel while attempting to navigate the scope through a dead‐end or blind segment.

Assessment of scope navigation requires the consideration of efficiency, patient comfort, and success at reaching the desired end point. Further assessment of navigation skills will be incorporated in the section on mucosal evaluation. Clearly, excellent control of the scope is required to thoroughly evaluate the entire mucosal surface.

Coordinating all of these maneuvers may seem overwhelming to a novice endoscopist, particularly if they occur during a particularly challenging point in an endoscopy. This raises several key points for the training of endoscopy. As these points are outlined, consider your own experience with trainees who are attempting to learn how to traverse the pylorus in upper endoscopy or to resolve a loop in lower endoscopy for example. The first training point is the need for using a common terminology during endoscopy [3, 4]. This is particularly important when several trainers are involved in training the same individual over time or when there is a potential for misinterpretation or misunderstanding. It is important to be as specific as possible in instruction so that the trainee understands what is to be accomplished, how it is to be accomplished, and how to assess the level of success. As an example, providing a specific instruction, such as giving a directional reference of “12 o’clock,” is more useful than “tip up.” Whenever possible, orienting the learner to the video image is preferable to providing instruction describing movements [11, 12].

Figure 2.1 An example of a stepwise or “progressive” model of simulation‐based training for endoscopy whereby learners gradually complete more difficult tasks as their skills improved. The simulators are matched to each task.

A second important consideration when giving feedback on performance during endoscopy is the influence of cognitive overload or dual task interference [13–15]. If a specific situation is particularly challenging to an individual, then they may not be able to pay attention to other “distractions” such as the voice of an instructor because all of their concentration is directed to the task at hand. This implies that feedback on performance should not be constant or ongoing, but rather be intermittent and focused. In particular, in situations where decision‐making may be involved, it may be more useful to have the trainee pause during the endoscopy, stabilize their position, and direct their attention to the trainer. This requires a significant level of trust and rapport between the trainer and trainee, and again illustrates the importance of attending to all aspects of training, including the training environment.

The concept of cognitive overload during endoscopy also illustrates the importance of using specific learning objectives at an appropriate level of difficulty for the learner. Learning activities should be focused on simple, well‐defined, and achievable points. Using a stepwise educational program can be useful since as each new skill is acquired, gradual introduction of progressively more difficult components of each task becomes easier as they build on prior successes [16]. Ideally, these steps are acquired along with conscious understanding of the steps and how they were taught, allowing the trainee to become a future trainer. This “progressive” learning approach can also be incorporated into simulation‐based training (Figure 2.1).