POEM Anesthesia Mastery: Safeguarding Achalasia Patients | Key Guide for Optimal Safety & Success

Introduction

Peroral Endoscopic Myotomy (POEM) has revolutionized the treatment of achalasia cardia, offering an effective and minimally invasive option for patients suffering from this challenging motility disorder. This innovative procedure, which combines the principles of endoscopy and natural orifice transluminal endoscopic surgery (NOTES), has gained prominence in the medical field since its inception in 2010. One of the critical aspects of POEM, which sets it apart from other treatment modalities, is its reliance on endoscopic techniques performed under general anesthesia. This collaborative approach between endoscopists and anesthesiologists has not only improved patient safety but has also expanded the boundaries of medical intervention for achalasia.

Achalasia, derived from the Greek word “chalasis,” meaning relaxation, is a chronic and debilitating disorder characterized by the dysfunction of the lower esophageal sphincter. Its prevalence, affecting approximately 10 in 100,000 individuals, underscores the need for effective treatment options. Patients with achalasia often endure distressing symptoms such as dysphagia, regurgitation, chest pain, and weight loss, making intervention imperative. While various treatment methods, including pharmacotherapy, botulinum toxin injections, pneumatic balloon dilatation, and laparoscopic Heller myotomy, have been employed to manage this condition, POEM has emerged as a game-changing alternative.

Procedure

The Peroral Endoscopic Myotomy (POEM) procedure is a carefully orchestrated sequence of steps that combines endoscopic techniques and surgical precision to treat achalasia cardia effectively. Here is a concise procedural sequence of a typical POEM:

1. Patient Positioning: The patient is positioned either in a supine or left lateral decubitus position to facilitate access to the esophagus and gastroesophageal junction (GEJ).
2. Preparation and Clearing: At the outset, any residual fluids or food present in the esophageal lumen are meticulously suctioned and removed using an esophagogastroduodenoscope (EGD) to ensure a clear field of view and a safe procedure.
3. Carbon Dioxide Insufflation: Carbon dioxide (CO2) is introduced into the esophagus at a low flow rate of approximately 1.2 liters per minute. This gentle inflation with CO2 helps create a safe working space and minimizes the risk of complications related to insufflation.
4. Mucosal Bleb Creation: With the assistance of EGD and a mucosal cap or hood at its tip, a mucosal bleb is generated approximately 10 to 12 centimeters above the gastroesophageal junction (GEJ). A solution containing normal saline mixed with a colored dye (typically methylene blue or indigo carmine) is used during this step to enhance visualization and provide a clear demarcation of the submucosal space.
5. Mucosal Incision: Using an electrocautery knife, a 2.5 to 3 centimeter longitudinal mucosal incision is made. This incision exposes the submucosal space and allows entry into the submucosal tunnel, a crucial component of the procedure.
6. Submucosal Dissection: Submucosal dissection is performed with precision, using the electrocautery knife. The dissection continues to create a submucosal tunnel, typically extending to about 3 centimeters below the GEJ. Dyed saline injections may be repeated to aid in this process.
7. Selective Myotomy: Approximately 2 to 3 centimeters distal to the mucosal incision site, a selective myotomy is executed. This step involves cutting the circular muscle fibers while sparing the underlying longitudinal fibers. The myotomy extends until approximately 2 centimeters below the GEJ.
8. Closure of Mucosal Entry Point: At the conclusion of the procedure, the initial mucosal entry point is closed. This is typically achieved using standard endoscopic hemo clips, ensuring that the integrity of the esophageal lining is restored.

Preoperative Considerations, Guidelines, and Patient Selection

Achalasia cardia is a debilitating motility disorder of the lower esophageal sphincter that often presents with symptoms such as dysphagia, regurgitation, chest pain, and weight loss. The effective management of this condition has seen remarkable advancements, with Peroral Endoscopic Myotomy (POEM) emerging as a transformative procedure. This endoscopic treatment offers hope to patients suffering from achalasia, but its success and safety are contingent on careful preoperative assessment and adherence to established guidelines. In this article, we delve into the critical preoperative considerations, fasting guidelines, and the indications and contraindications for POEM.

Preoperative Investigations

Cardiac Evaluation

Patients with retrosternal chest pain or those at risk for pre-existing cardiac conditions should undergo a preprocedural electrocardiogram (ECG). This precautionary measure helps rule out any underlying cardiac ailments, ensuring that the patient’s cardiovascular health is optimized before the procedure.

Pulmonary Assessment

In cases where there is a clinical suspicion of pulmonary infiltrates or a history of regurgitation, a chest X-ray may be necessary to assess the pulmonary status of the patient. This evaluation is crucial to detect and address any potential respiratory complications.

Fasting Guidelines for Achalasia Cardia Before POEM

Fasting guidelines for patients undergoing POEM are a topic of consideration and debate. As of now, there is no universal guideline for pre-fasting time specific to POEM. Several case series on POEM anesthesia management have reported varying fasting times, ranging from 8 to 48 hours. The diversity in recommendations has prompted a need for clarity in this regard.

However, a consensus is emerging that pre-fasting before POEM can contribute to patient safety. The majority of case series recommend a clear liquid diet for at least 24 hours or a low-residue diet for 48 hours before the procedure. At many centers, patients are kept on a clear liquid diet for 24 hours, followed by a 12-hour fasting period.

The rationale behind pre-fasting is to reduce the risk of aspiration during the procedure. Achalasia patients are particularly prone to aspiration due to reflux of esophageal contents caused by impaired esophageal emptying. By ensuring an empty stomach, the risk of complications related to aspiration is mitigated.

The use of prophylactic esophagogastroduodenoscopy (EGD) to remove residual food before the induction of anesthesia remains a subject of debate. Some studies advocate for the necessity of prophylactic EGDs, while others have reported an increased risk of aspiration when EGD is not performed. As a result, the decision regarding the use of EGD should be made based on individual patient characteristics and clinical judgment.

Indications and Contraindications for POEM

POEM has gained prominence as the preferred treatment for specific patient populations. According to recent guidelines from the American Society for Gastrointestinal Endoscopy (ASGE), POEM is recommended for the management of patients with type III achalasia. Additionally, POEM has shown success in treating conditions beyond achalasia, including diffuse esophageal spasm, nutcracker esophagus, and hypercontractile (jackhammer) esophagus.

However, there are specific contraindications that must be considered:

Indications for POEM:

1. Type III achalasia
2. Diffuse esophageal spasm
3. Nutcracker esophagus
4. Hypercontractile (jackhammer) esophagus

Contraindications for POEM:

1. Severe cardiopulmonary or serious systemic diseases leading to unacceptable surgical risk
2. Pseudoachalasia
3. Anticipated difficulty in creating submucosal tunnel due to severe fibrosis and adhesion
4. Severe thrombocytopenia (<30,000/mL)
5. Myelodysplastic syndrome
6. Hypersplenism
7. Mechanical heart valves requiring high-dose anticoagulation

Periprocedural anticoagulation and/or antiplatelet therapy should be maintained according to the ASGE guidelines to balance the risk of thrombosis and bleeding during and after the procedure.

To reduce the risk of postprocedural inflammatory response and complications, prophylactic measures may include the use of proton pump inhibitors, antibiotic prophylaxis, and decontamination of the oral cavity with chlorhexidine.

In conclusion, POEM has emerged as a groundbreaking treatment for achalasia cardia and related esophageal conditions. However, ensuring the safety and success of this procedure hinges on meticulous preoperative evaluations, fasting guidelines, and careful patient selection based on the established indications and contraindications. By adhering to these guidelines and individualizing patient care, healthcare providers can provide effective treatment and improve the quality of life for those suffering from achalasia.

Physiological Changes During Peroral Endoscopic Myotomy (POEM) with Endotracheal Intubation and General Anesthesia

Peroral Endoscopic Myotomy (POEM) has emerged as a groundbreaking procedure for treating esophageal motility disorders like achalasia cardia. While the benefits are substantial, it is essential to explore potential adverse effects, especially those related to the physiological changes induced by the procedure and the use of gas insufflation, conducted under endotracheal intubation and general anesthesia.

Continuous Gas Insufflation

A crucial element of POEM involves creating a submucosal tunnel and maintaining proper visualization, both relying on continuous gas insufflation. Carbon dioxide (CO2) is the preferred gas due to its safety features. It is non-combustible, water-soluble, and rapidly absorbed and excreted by the body. Importantly, the use of air insufflation in POEM is strictly contraindicated, emphasizing the importance of CO2 insufflation.

Physiological Effects Under General Anesthesia

POEM is performed under general anesthesia, with endotracheal intubation ensuring controlled ventilation. This combination induces significant physiological changes. The anesthetic agents and controlled ventilation can lead to a rise in mean arterial pressure (MAP) and heart rate (HR). Factors such as systemic absorption, sympathetic stimulation, and increased catecholamine release contribute to these changes. Patients with compromised cardiopulmonary function may experience more pronounced physiological responses.

Respiratory Acidosis and Intra-Abdominal Pressure

Persistent CO2 insufflation, integral to POEM, can disrupt systemic CO2 balance, potentially causing respiratory acidosis and increased peak airway pressure. Elevated peak airway pressure indicates heightened intra-abdominal pressure, which may be attributed to gastric distension, retroperitoneal gas (capnoretroperitoneum), or pneumoperitoneum. This emphasizes the importance of close monitoring during the procedure.

Management Strategies

Effective management strategies are vital to navigate the intricacies of physiological responses during POEM with endotracheal intubation and general anesthesia. Continuous monitoring of hemodynamic parameters, such as MAP and HR, is essential. Additionally, vigilant observation of respiratory parameters, including peak airway pressure, is crucial to detecting any signs of respiratory acidosis. Adjusting ventilator settings and ensuring proper ventilation management contribute to mitigating these challenges.

In conclusion, while POEM with endotracheal intubation and general anesthesia offers a revolutionary approach for esophageal motility disorders, understanding and managing associated physiological changes and potential adverse effects are paramount. Diligent attention to gas insufflation, physiological responses, and meticulous perioperative care, including endotracheal intubation and general anesthesia, contributes to the overall success and safety of the POEM procedure.

POEM-Related Adverse Events

Early Adverse Events: The POEM procedure may lead to several early adverse events, including mucosal injury, bleeding, subcutaneous emphysema, capnothorax, capnomediastinum, capnoperitoneum, and pleural effusion. Late complications are related to patient outcomes, such as symptomatic gastroesophageal reflux disease and esophagitis.

Insufflation-Related Adverse Events: The most common adverse events associated with POEM are related to gas insufflation, including pneumomediastinum, pneumothorax, pneumoperitoneum, and subcutaneous emphysema.

Reducing Adverse Events: Two main factors are essential to reduce these complications: using CO2 instead of air for insufflation and minimizing the total volume of gas insufflated.

Managing Subcutaneous Emphysema: Subcutaneous emphysema is one of the most common insufflation-related adverse events.

Percutaneous Abdominal Needle Decompression: Increased abdominal pressure can compromise pulmonary mechanics and cardiac function.

Postoperative Pain Control

Challenges of Postoperative Pain: Postoperative pain is a significant concern following POEM. It can be a distressing experience for patients and may lead to undesirable side effects, including cardiovascular effects, respiratory depression, urinary and digestive dysfunction, and neuroendocrine dysfunction. Effective pain management is vital for patient comfort and recovery.

Patient-Controlled Analgesia (PCA): Patient-controlled analgesia is a common approach for postoperative pain control in POEM. PCA allows patients to self-administer opioids as needed, providing a tailored solution for individual pain levels.

Opioids in PCA: Opioids are frequently used in PCA due to their potent analgesic effects. However, they can be associated with adverse events such as nausea, vomiting, pruritus, and respiratory depression.

Adjunctive Medications: To minimize opioid-related side effects, adjunctive medications may be used in combination with opioids. These may include non-steroidal anti-inflammatory drugs, ketamine, and anti-emetics. Recent studies suggest that combining dexmedetomidine with opioid-based PCA can enhance analgesia, reduce opioid consumption, and decrease opioid-related adverse events.

Postoperative Nausea and Vomiting (PONV)

Risk of PONV: Both general anesthesia and opioid use can contribute to postoperative nausea and vomiting (PONV). PONV immediately following the POEM procedure can be problematic, potentially leading to bleeding or harm at the surgical site. Various factors influence the incidence of PONV, including patient characteristics, anesthesia methods, the surgical procedure, and postoperative care.

Risk Factors: Identified risk factors for PONV include female sex, non-smoking status, a history of motion sickness, and postoperative opioid use.

Preventive Measures: Propofol is known for its antiemetic properties and is often used to reduce the incidence of PONV. Total intravenous anesthesia with propofol has been effective in this regard. Additionally, serotonin (5-hydroxytryptamine, subtype 3 [5-HT3]) receptor antagonists are widely used for their minimal side effects. These drugs are divided into first-generation (ondansetron, granisetron, ramosetron, and tropisetron) and second-generation (palonosetron) 5-HT3 receptor antagonists.

Choice of Medications: If a patient is at risk of PONV, 5-HT3 antagonists are the first choice for preventive treatment. Other drugs, such as metoclopramide and dexamethasone, can also be employed for both prevention and treatment of PONV.