Insertion Through the Mouth Anterograde Approach

Before starting the oral insertion, a lubricant (such as Xylocaine jelly) is applied to the distal end of the endoscope (including the balloon). As in the case of upper gastrointestinal endoscopy, a mouthpiece is used. The endoscope is advanced into the stomach without the aid of an assistant, as in the case of conventional upper gastrointestinal endoscopy. Unlike the conventional upper gastrointestinal endoscope, the thin, flexible endoscope tends to bend in the mouth, and it is rather difficult to transmit the force to the endoscope tip. Another difference is that the endoscope between the two hands tends to trail down because of its long total length. These two issues can be addressed by inserting the overtube along the endoscope with the assistant holding the overtube; therefore, attention is given to these issues only during the initial phase of insertion.

When the endoscope tip is advanced into the stomach, gastric contents are suctioned well to prevent aspiration during the examination and unnecessary looping in the stomach. Air insufflation should be kept to a minimum, and the endoscope tip is advanced to the gastric antrum.

At this stage, the assistant stands between the operator and the patient to insert the overtube along the endoscope while straightening the overtube. The overtube is inserted with the balloon at the endoscope tip deflated because inflation of the balloon in the stomach may damage the balloon. Because insertion through the mouth causes the greatest discomfort to the patient when the endoscope and the overtube advance beyond the larynx, application of adequate lubricant jelly is necessary at the time of the initial insertion of the endoscope as well as insertion of the overtube. Manipulation of the endoscope without movement of the overtube causes no irritation in the larynx, but manipulation of the overtube may irritate the larynx and cause discomfort to the patient. Thus, the overtube should be gently manipulated with particular attention paid to this point.

After the rear end of the overtube reaches the 155-cm marking on the endoscope, the endoscope tip is advanced into the descending or horizontal part of the duodenum with the overtube balloon deflated, after which the balloon at the endoscope tip is inflated. The overtube is inserted along the endoscope until the rear end of the overtube reaches the 155-cm marking on the endoscope; then the overtube balloon is inflated to secure the tip of the overtube in the duodenum. When it is difficult to insert the overtube, pulling back and straightening the endoscope may facilitate insertion, as in the case of conventional upper gastrointestinal endoscopy.

The tip of the overtube may not be secured in the duodenum and may slip back into the stomach. One can estimate whether it is successfully secured on the basis of the condition of the air supply from the pump. A small volume of air allows the internal pressure of the balloon in the duodenum to reach the set pressure, and the pump automatically stops supplying air. When the balloon is in the stomach, however, even a large volume of air may fail to elevate the balloon pressure, and an alarm is activated. In such cases, the pump should be stopped temporarily because continued air supply from the pump may damage the balloon. In this case, there should be no further attempts to secure the tip of the overtube in the duodenum at this stage. Instead, the balloon at the endoscope tip is deflated, and the endoscope is pushed into the deeper portion of the duodenum. Then the balloon at the endoscope tip is inflated, the overtube is advanced again, and the tip of the overtube is secured in the duodenum.

After the endoscope and the overtube are withdrawn with both balloons inflated to reduce looping in the stomach, the balloon at the endoscope tip is deflated, and the endoscope is advanced beyond the ligament of Treitz. During the process, the tip of the overtube is secured in the duodenum, which allows deep insertion of the endoscope without loops in the stomach.

The endoscope is advanced as far as possible, and the balloon at the endoscope tip is inflated and secured in the intestine. Then the overtube balloon is deflated, and the overtube is inserted along the endoscope. After the overtube balloon is inflated again and secured in the intestine, both the endoscope and the overtube are pulled back slowly with both balloons inflated to eliminate redundant loops, followed by deflation of the balloon at the endoscope tip and insertion of the endoscope. These procedures are repeated to advance the endoscope while the fixed support established by the overtube balloon is moved more deeply (Fig. 8.2).

Fig. 8.2. Insertion

Fig. 8.2. Insertion through the mouth

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