Peroral Endoscopic Myotomy (POEM)

A never-empty esophagus - an achalasic esophagus sits above a sphincter that does not open, so it holds undigested food and secretions from previous days no matter how long the patient has fasted. Nothing on the fasting record tells you it is empty. Build the anesthetic around a full stomach.

Preoperative preparation - the reservoir empties by dilution, not by time, so many centers use clear liquids for 24 to 48 hours beforehand and ask the patient to sleep propped up. Ask about nocturnal regurgitation, waking with food on the pillow, and treated pneumonia, which mean months of microaspiration and less reserve than the chart suggests.

Cuffed tube, not sedation - this is a shared airway with active insufflation into a lumen that drains straight into the pharynx, and a supraglottic device protects against neither regurgitated retained food nor gas pushed up the esophagus. Do not let the endoscopy-suite setting talk you into sedation.

Induction and suction - rapid sequence induction with the head elevated and large-bore suction already in your hand before drugs go in. Head-up positioning uses gravity to hold the passive column below the cricopharyngeus while you secure the airway, since there is no functioning sphincter at either end of it.

Clearance before the tunnel - once the cuff is up, the endoscopist should suction and lavage the esophagus empty under vision before any dissection starts. Watch that this actually happens, because it is your best protection for the rest of the case and it gets rushed when the room is behind.

Nothing passed blindly - pass nothing blindly down the esophagus at any point, and say so to anyone else working at the head of the bed, because after the mucosotomy an orogastric tube can go straight through the fresh closure.

Expected gas findings - the tunnel is created and held open with insufflated gas that dissects through the esophageal wall, so capnoperitoneum, capnomediastinum, capnothorax and subcutaneous emphysema up the neck and chest are common findings rather than disasters, and most settle on their own once insufflation stops.

CO2, never room air - confirm what the insufflator is running before the case starts. CO2 is absorbed and reabsorbed within hours, while air is not and can produce a persistent gas embolism or a trapped pneumothorax.

Tense capnoperitoneum - gas tracking into the peritoneum can accumulate faster than it is absorbed and splint the diaphragm: rising peak inspiratory pressure, falling tidal volume, hypotension, and a tympanitic distended abdomen. Say it out loud to the endoscopist and have it decompressed with a Veress needle rather than fighting the ventilator.

Absorbed CO2 versus capnothorax - both raise the end-tidal CO2; airway pressure separates them. A steady climb with stable peak pressures and blood pressure is absorption: increase minute ventilation. An abrupt peak pressure jump with desaturation, hypotension and unilateral breath sounds is tension capnothorax - stop insufflation and decompress.

Deep paralysis - the tunnel dissection runs millimeters off intact mucosa and a single cough or diaphragmatic twitch perforates it, so maintain deep neuromuscular blockade for the whole dissection and judge depth with quantitative twitch monitoring, not clinical impression.

Emergence and recovery - the aspiration risk does not stop when the scope comes out. Have the pharynx and esophagus suctioned under vision before withdrawal, extubate awake, and keep the patient head-up through transport with suction on the bed. Give antiemetic prophylaxis: retching against a fresh mucosal closure threatens the repair.

Achalasia is the loss of inhibitory ganglion cells in the myenteric (Auerbach) plexus of the distal esophagus. Without them the lower esophageal sphincter (LES) never relaxes fully and the esophageal body loses coordinated peristalsis, so the gastroesophageal junction becomes a functional obstruction with no pump behind it. Over years the esophagus above dilates into a passive reservoir that collects saliva, undigested food, and pills, and empties only by gravity and overflow. Patients report dysphagia to both solids and liquids, regurgitation of old food, nocturnal cough, and weight loss. POEM relieves the obstruction from inside the lumen: the endoscopist tunnels under the mucosa and divides the circular muscle of the LES, leaving the mucosa intact and the abdomen unopened. No anti-reflux wrap is built, so postoperative reflux is the accepted trade.

Setup - the patient is supine with the table tilted head-up, a cuffed endotracheal tube in place, and a therapeutic gastroscope with a distal cap and a CO2 insufflator. There is no incision anywhere on the body surface; everything happens through the mouth.

Esophageal clearance - the scope is passed and the retained column of saliva and undigested food is suctioned and lavaged out under direct vision before any dissection begins. In a dilated esophagus this can take several minutes and several liters of irrigation.

Mucosotomy - a submucosal cushion is raised with injected saline and dye roughly 10 to 15 cm proximal to the gastroesophageal junction, and a 1.5 to 2 cm longitudinal mucosal incision is cut to make the tunnel entrance.

Submucosal tunnel - the scope is driven into the plane between mucosa and muscularis and the tunnel is dissected downward past the gastroesophageal junction and 2 to 3 cm onto the gastric cardia. This is the millimetric part of the case and the reason the field must be dead still.

Myotomy - the circular muscle fibers are divided from inside the tunnel, starting several centimeters above the junction and carried across the LES onto the cardia. Anterior or posterior orientation is surgeon preference; the gastric extension is what actually relieves the obstruction.

Closure and leak check - the scope is withdrawn from the tunnel and the mucosotomy is closed with endoscopic clips or endoscopic suturing, then inspected for a mucosal breach. A missed full-thickness defect becomes mediastinitis.

Decompression - insufflated CO2 is aspirated from the esophagus and stomach at the end, and a tense capnoperitoneum is vented with a Veress needle in the left upper quadrant before the patient leaves the room.

Botulinum toxin injection - the lowest rung of the same treatment ladder and a different operation entirely: 80 to 100 units of botulinum toxin injected endoscopically into the LES in quadrants, taking a few minutes, no tunnel and no insufflation beyond routine endoscopy. It buys months rather than years, is repeatable, and is reserved for patients who are poor candidates for myotomy or dilation.

Botulinum toxin injection of the LES is the lowest rung of the same ladder and you will be asked to anesthetize it. It is a short endoscopic procedure, often in the endoscopy suite, and the temptation is to do it under sedation because it only takes a few minutes. The esophagus is exactly as full as it is for a POEM, so the same logic applies: clear liquids beforehand, head-up, suction ready, and a low threshold for a cuffed tube in anyone with nocturnal regurgitation, a markedly dilated esophagus on imaging, or prior aspiration. The procedure being brief does not make the airway safer.

Ask about prior botulinum toxin or pneumatic dilation before a POEM. Both scar the submucosal plane, which makes the tunnel slower and more likely to breach the mucosa, so a longer case with more insufflation and a higher perforation risk is predictable from the history alone.

Postoperative reflux is the expected long-term trade-off of POEM because no anti-reflux wrap is created, and this matters to you on any future anesthetic for these patients. Subcutaneous emphysema in the neck and chest in recovery is usually reabsorbing CO2 and settles over hours, but new hypoxemia, chest pain out of proportion, fever, or emphysema that is still expanding should be worked up for a mucosal leak rather than written off as gas.

Routine invasive monitoring is not warranted. Standard monitors, one good peripheral IV, and modest fluids are appropriate for most of these patients, though many are volume depleted and undernourished from months of dysphagia, so anticipate hypotension on induction and have a vasopressor drawn up rather than chasing it with volume.