After the patient is intubated in the operating room, the endotracheal tube is secured to the right side of the mouth. He/she will need to be under general endotracheal anesthesia for the entirety of the case. Preoperative antibiotics are used prior to mucosotomy—a second-generation cephalosporin is administered. Sequential compression devices are used for deep vein thrombosis prophylaxis. Subcutaneous heparin and urinary catheters are not routinely used, given the relatively short duration of the procedure, typically less than two hours. The left arm is tucked due to the placement of equipment on the patient’s left side. The right arm can remain abducted. The patient’s abdomen is exposed to periodically monitor for gastric distention and pneumoperitoneum. Figure 5.3 shows the patient on the operating room table, the position of the monitor, and the anesthesia equipment.

Step stools are placed at the head of the bed. For optimal comfort and positioning, the operating surgeon stands on the step stools a few steps away from the patient’s head. The energy foot pedal is placed on one of the stools. He/she will be manipulating the gastroscope dials and instruments via the channel as well as controlling the energy foot pedal. The assistant surgeon supports and manipulates the gastroscope. He/she usually stands to the left of the operating surgeon and closer to the patient. An endoscopic assistant can stand to either side of the surgeons. We recommend the involvement of two surgeons for the procedure, generally an attending surgeon and a surgical fellow or chief resident at our institution, with additional assistants as needed.

The overtube is loaded onto the gastroscope, as shown in Fig. 1.1. The air is turned off and the CO₂ is turned on at this point. After passing the gastroscope into the esophagus, the overtube is advanced such that the end of the overtube is placed in the proximal esophagus. This allows the gastroscope to pass in and out easily with minimal trauma to the oropharynx and proximal esophagus. The esophagus is assessed and suctioned of all fluid and food debris. This may require the assistance of a double-channel therapeutic gastroscope. The stomach is assessed, taking care to examine the gastroesophageal (GE) junction on retroflexion to exclude neoplasms as a source for pseudoachalasia. The distance from the incisors to the GE junction is measured several times with the overtube in place. A flashlight is used to aid in seeing the marks on the gastroscope while the operating room lights are dimmed.

The gastroscope is removed, and the cap is secured to the end with an electrical tape. The hole in the cap is positioned at 6 o’clock to facilitate drainage of the water used to wash the lens. We found that electrical tape works well in keeping the cap firmly secured. The gastroscope is advanced again until it is approximately 14 cm from the GE junction. The distance from the GE junction and the anterior/posterior position on which to create the mucosotomy varies among operators. Some groups begin the mucosotomy at 6 cm from the GE junction [5], some use 7–10 cm [6], and some use 10–15 cm [7]. We choose to use 14 cm from the GE junction in the event there is mucosal damage while creating the proximal submucosal tunnel. To determine the anterior and posterior esophageal walls, a small volume of Methylene Blue is injected in the lumen with the Articulator injection needle, and the orientation is determined by gravity, as shown in Fig. 5.4. The anterior approach is thought to be technically easier than the posterior approach [1]. For patients who have not previously undergone myotomy for achalasia, we use a strictly anterior approach at the 12 o’clock position. Some groups create the submucosal tunnel at the 2 o’clock [1] or 3 o’clock [7] position in order to be aligned with the lesser curvature of the stomach. The angle of His, which is at approximately 8 o’clock with the patient supine, is avoided to prevent disturbance of natural antireflux mechanisms. For patients who have previously undergone Heller myotomy with fundoplication for achalasia, the patient is routinely positioned with several blankets under the right side, so that the adjusted 12 o’clock position is aligned with the lesser curvature of the stomach. However, another consideration for those who have undergone anterior myotomies via Heller or POEM is a posterior approach [8]. There are groups that routinely utilize the posterior approach for the POEM, with results similar to those using the anterior approach [9, 10]. There currently is no clear evidence that one approach is more effective for first-time myotomies. Once the position of the mucosotomy is determined, the Articulator injector needle is used to inject 8–10 cm³ of the Methylene Blue solution into the submucosal space to lift the mucosa from the muscular layers, as shown in Fig. 5.5. A 2 cm longitudinal mucosotomy is created with the triangle-tip knife on the cut current, as shown in Fig. 5.6 [10]. The length of the mucosotomy is likely not significant, provided the gastroscope with the cap affixed can easily fit into the submucosal space, and the entire length of the mucosotomy is closed securely at the conclusion of the procedure. If the mucosotomy is created and is not long enough for the cap and endoscope to easily pass, the mucosotomy may inadvertently tear, resulting in a longer mucosotomy that will require closure.