BASIC INFORMATION

Date & Time: March 19, 2026, 12:58:30 Indian Standard Time

Lecture Handout Prepared from the Teaching Session by: Dr. R. K. Mishra

SUMMARY

This lecture provides a comprehensive, multidisciplinary overview of Enhanced Recovery After Surgery (ERAS) pathways in bariatric surgery. It integrates anesthetic and surgical strategies aimed at attenuating the physiological stress of surgery, optimizing pain management, and accelerating recovery. The content details the evolution and key components of ERAS, including prehabilitation, advanced intraoperative monitoring, and evidence-based postoperative care. A significant focus is placed on opioid-sparing and opioid-free techniques, comparing various regional anesthetic blocks such as the transversus abdominis plane (TAP) block, erector spinae plane (ESP) block, and a novel intraoperative autonomic blockade. The lecture presents strong evidence for the efficacy of these targeted blocks in controlling visceral pain and reducing postoperative nausea and vomiting (PONV). Furthermore, it addresses the critical issue of venous thromboembolism (VTE) prophylaxis, critically evaluating the limitations of traditional low-molecular-weight heparin (LMWH) and presenting a modern protocol using direct oral anticoagulants (DOACs), specifically Apixaban, based on pharmacokinetic data and extensive clinical experience. The overall goal is to equip surgeons with a holistic, evidence-based framework for improving patient outcomes, reducing complications, shortening hospital stays, and supporting the trend towards outpatient bariatric procedures.

KEY KNOWLEDGE POINTS

• Principles of the ERAS pathway in bariatric surgery, encompassing pre-admission (prehabilitation), intraoperative, and postoperative phases.

• The concept of "precision anesthesia" guided by advanced monitoring of hemodynamics, depth of anesthesia, and neuromuscular blockade.

• Rationale and techniques for opioid-sparing and opioid-free anesthesia, including the use of multimodal analgesics and regional blocks.

• Anatomy, technique, and outcomes of a novel intraoperative autonomic blockade targeting the vagus nerve and celiac plexus for superior visceral pain control.

• The high risk of venous thromboembolism (VTE) in bariatric patients and the limitations of traditional LMWH prophylaxis, including the phenomenon of reactive thrombosis.

• Pharmacokinetic considerations and clinical evidence supporting the use of Direct Oral Anticoagulants (DOACs), particularly Apixaban, for extended VTE prophylaxis.

• The synergistic benefits of integrating advanced anesthetic, surgical, and pharmacological strategies to reduce opioid use, shorten hospital stays, and minimize complications like PONV and VTE.

INTRODUCTION

The field of bariatric surgery has undergone a significant paradigm shift, moving beyond mere technical proficiency to a holistic, multidisciplinary approach focused on optimizing the entire perioperative journey. Enhanced Recovery After Surgery (ERAS) protocols, which aim to mitigate the surgical stress response and accelerate a return to normal function, are now the standard of care. This evolution is driven by the unique physiological challenges of patients with obesity, including altered pharmacokinetics, increased cardiopulmonary risk, and a prothrombotic state. Key challenges such as postoperative visceral pain, nausea, vomiting, and the life-threatening risk of venous thromboembolism (VTE) demand innovative solutions. This lecture will review novel anesthetic and surgical strategies integral to a modern ERAS pathway, detailing advanced techniques for pain management, such as intraoperative autonomic blockade, and evidence-based protocols for VTE prophylaxis using direct oral anticoagulants (DOACs). The integration of these strategies is critical for improving patient safety, enhancing recovery, and facilitating the transition to ambulatory bariatric surgery.

LEARNING OBJECTIVES

• To understand the fundamental principles and components of the ERAS pathway in bariatric surgery, including prehabilitation and advanced intraoperative management.

• To evaluate the efficacy and techniques of different regional anesthetic blocks, particularly intraoperative autonomic blockade, for controlling visceral pain and PONV.

• To analyze the evidence supporting the use of DOACs, specifically Apixaban, for extended VTE prophylaxis, and to understand the pharmacokinetic considerations in post-bariatric patients.

• To learn an integrated, evidence-based perioperative protocol that minimizes opioid use, reduces VTE risk, and facilitates accelerated patient recovery.

CORE CONTENT

1. The ERAS Pathway and Precision Anesthesia

Enhanced Recovery After Surgery (ERAS) is a structured, evidence-based, multidisciplinary approach to perioperative care. The ENERGY trial, a large MBSAQIP project, validated its safe implementation in bariatric surgery.

1.1. Phases and Key Components of ERAS

• Pre-admission Care (Prehabilitation): Optimizing the patient's condition before surgery is crucial.

  • Patient Education: Strongly recommended to manage expectations and improve compliance, despite a low level of evidence.

  • Smoking Cessation: Recommended for at least one month preoperatively to reduce pulmonary and surgical complications.

  • Metabolic Optimization: Stabilizing blood glucose and encouraging preoperative weight loss are associated with lower complication rates.

  • Minimized Fasting: Allowing solids up to six hours and clear liquids up to two hours preoperatively preserves energy and can reduce PONV.

• Intraoperative Management: Focuses on minimizing physiological stress and maintaining homeostasis.

  • Multimodal Analgesia: Combining non-opioid analgesics, regional blocks, and adjunctive agents to spare or eliminate opioids.

  • Optimized Fluid Management: Goal-directed fluid therapy to avoid both hypovolemia and fluid overload.

  • Protective Ventilation and Low-Pressure Pneumoperitoneum: Using deep neuromuscular blockade allows for surgery at lower intra-abdominal pressures (8-10 mmHg), reducing hemodynamic instability and postoperative pain.

• Postoperative Care: Aimed at rapid recovery.

  • Early Mobilization and Feeding: Encourages gut function and prevents complications like VTE and pneumonia.

  • PONV Prophylaxis: Can reduce incidence by 20-50%.

  • Thromboprophylaxis: Essential for all bariatric patients.

1.2. Precision Anesthesia and Advanced Monitoring

A personalized approach is superior to a generic protocol and relies on comprehensive monitoring.

• Hemodynamic Monitoring: Use of continuous non-invasive or minimally invasive systems to monitor mean arterial pressure (MAP), cardiac output, and stroke volume variation (SVV) to guide fluid and vasopressor therapy. Maintaining MAP >60-65 mmHg is critical.

• Depth of Anesthesia Monitoring: Processed EEG (e.g., BIS) helps avoid excessively deep or light anesthesia, reducing the risk of hypotension, delirium, and awareness.

• Neuromuscular Blockade (NMB) Monitoring: Quantitative Train-of-Four (TOF) monitoring allows for deep muscle relaxation, which is essential for low-pressure pneumoperitoneum.

2. Opioid-Sparing Pain Management: B-STOP and Regional Anesthesia

Minimizing opioid use is a central tenet of modern bariatric surgery to reduce side effects like PONV, ileus, and respiratory depression. The B-STOP (Bariatric Surgery Targeting Opioid-Free Postoperative Pain Management) protocol formalizes this approach.

2.1. The B-STOP Protocol

This MBSAQIP quality initiative focuses on preemptive, multimodal analgesia.

• Non-Opioid Analgesics: Preoperative administration of acetaminophen and NSAIDs.

• Regional Anesthesia: Techniques such as TAP blocks, local anesthetic infusion pumps (On-Q), or long-acting local anesthetics (Exparel).

• Adjunctive Agents: Intraoperative ketamine infusions are particularly useful for patients with chronic pain.

2.2. A Novel Approach: Intraoperative Autonomic Blockade

This surgeon-performed technique directly targets the visceral pain pathways responsible for significant postoperative morbidity.

• Technique: Performed at the start of surgery, it involves injecting a mixture of 0.5% bupivacaine with 8 mg of dexamethasone at two key sites:

  1. Celiac Plexus Block: Around the base of the left gastric vessels, accessed by creating a window in the lesser omentum. This blocks sympathetic visceral pain transmission.

  2. Vagus Nerve Block: Along the path of the anterior vagus nerve on the lesser curvature of the gastric sleeve. This blocks parasympathetic input, reducing gastric tone and intraluminal pressure.

• Outcomes: Randomized trials show this technique significantly reduces intraoperative anesthetic requirements, postoperative pain scores for 18-20 hours, opioid consumption, and PONV, with many patients discharged on oral paracetamol alone.

2.3. Comparison of Regional Blocks

• Transversus Abdominis Plane (TAP) Block: Provides somatic analgesia but is often insufficient as it does not cover the visceral pain component.

• Erector Spinae Plane (ESP) and Paraganglionic Blocks: These are more effective as they provide better visceral analgesia, reducing pain and opioid consumption.

• Intraoperative Autonomic Blockade: Offers the most targeted approach for visceral pain originating from the stomach, with proven benefits for both intraoperative stability and postoperative recovery.

3. VTE Prophylaxis: Beyond LMWH to DOACs

VTE is the leading cause of mortality after bariatric surgery. All patients are considered high-risk and require prophylaxis.

3.1. Limitations of Low-Molecular-Weight Heparin (LMWH)

While the traditional standard, LMWH has significant drawbacks:

• Poor Compliance: Daily subcutaneous injections lead to low patient adherence.

• Economic Burden: Can be costly for patients.

• Reactive Thrombosis: Sudden cessation of a short course (7-14 days) can induce a rebound hypercoagulable state, leading to thrombotic events. This has been observed with an incidence of approximately 0.5%.

3.2. Direct Oral Anticoagulants (DOACs)

DOACs offer an effective and patient-friendly alternative.

• Pharmacokinetic Considerations: Drug absorption can be altered by bariatric procedures.

  • Rivaroxaban: Absorption is significantly decreased after Roux-en-Y Gastric Bypass (RYGB). It has also been associated with a higher rate of bleeding complications (up to 7.6% endoluminal bleeding in RYGB patients in one series).

  • Apixaban: Absorption is minimally affected by both Sleeve Gastrectomy and RYGB, making it a more reliable option. It has an excellent safety profile with a very low incidence of clinically significant bleeding.

• Recommended Protocol (Based on >1,000 patient series):

  • Perioperative: Mechanical prophylaxis (IPC devices) and aggressive early ambulation.

  • Postoperative Day 0-2: Continue mechanical prophylaxis and hydration. No routine chemoprophylaxis to minimize early bleeding risk.

  • Postoperative Day 3 to Day 30: Initiate Apixaban 2.5 mg twice daily for one month.

• Outcomes: This protocol has been shown to be highly effective in preventing VTE with no clinically significant bleeding events and superior patient compliance.

SURGICAL PEARLS

• A robust preoperative education program is a low-risk, high-reward intervention that significantly improves patient compliance and outcomes.

• Performing an intraoperative autonomic blockade at the beginning of the procedure provides dual benefits: reduced intraoperative anesthetic needs and prolonged postoperative analgesia.

• When performing the autonomic block, always aspirate before injecting to prevent intravascular injection. Visualizing the elevation of the vagus nerve by the fluid confirms correct placement.

• Deep neuromuscular blockade allows the surgeon to operate with lower insufflation pressures (8-12 mmHg), reducing postoperative shoulder-tip pain and cardiorespiratory compromise.

• Reactive thrombosis after LMWH cessation is a real phenomenon. Avoid short, finite courses (7-10 days). An extended 28-day course of a DOAC like Apixaban is a safer strategy.

• For patients with chronic pain, consider an intraoperative ketamine infusion to enhance analgesia and reduce postoperative opioid requirements.

ANESTHETIC AND PHYSIOLOGICAL CONSIDERATIONS

• GLP-1 Agonists: These medications delay gastric emptying. It is recommended to stop them approximately two weeks before surgery to reduce the risk of aspiration. For patients with severe GERD, extending the clear liquid fasting time from two to four hours should be considered.

• Opioid-Sparing Synergy: The combination of ERAS principles (preoperative non-opioids), regional anesthesia (autonomic blockade), and adjunctive agents creates a powerful synergistic effect that dramatically reduces or eliminates the need for opioids.

• Intraoperative Hemodynamics: An effective autonomic blockade may cause a modest decrease in heart rate and MAP, indicating a reduction in sympathetic tone and blunting the stress response to surgery.

COMPLICATIONS AND THEIR MANAGEMENT

• Intraoperative

  • Intravascular Injection: The primary risk of autonomic blockade, avoided by aspiration.

  • Hypotension: Managed proactively with goal-directed fluid therapy and vasopressors, guided by advanced hemodynamic monitoring.

• Early Postoperative

  • Postoperative Nausea and Vomiting (PONV): Minimized with prophylactic multimodal antiemetics and opioid-sparing techniques, particularly effective visceral blockade.

  • Bleeding: The risk of early postoperative bleeding is mitigated by delaying chemoprophylaxis until postoperative day three, as in the Apixaban protocol.

• Late Postoperative

  • Venous Thromboembolism (VTE): Risk is highest after cessation of inadequate prophylaxis. An extended one-month course of a DOAC is designed to prevent this.

  • Opioid Dependence: Risk is significantly reduced by limiting perioperative exposure and minimizing discharge prescriptions, a core goal of the B-STOP protocol.

MEDICOLEGAL AND PATIENT SELECTION CONSIDERATIONS

• All bariatric surgery patients must be considered high-risk for VTE and receive appropriate prophylaxis.

• Patient individualization is key. Deviating from a standard protocol (e.g., extending fasting times for patients with severe GERD) is a mark of good clinical judgment.

• The decision for postoperative disposition (ward vs. ICU) should be based on preoperative risk factors (e.g., OS-MRS score) and intraoperative physiological stability.

• Patients with obstructive sleep apnea (OSA) should be instructed to bring and use their home CPAP device postoperatively.

• Clear communication regarding realistic pain management expectations is crucial. The goal is manageable pain that allows for mobilization, not zero pain.

SUMMARY AND TAKE-HOME MESSAGES

• The integration of ERAS, B-STOP, and advanced anesthetic techniques is the current standard of care for optimizing outcomes in bariatric surgery.

• A multimodal, opioid-sparing analgesia regimen is a cornerstone of modern practice. Intraoperative autonomic blockade is a highly effective surgical technique to control visceral pain and PONV.

• Extended VTE prophylaxis with a DOAC is superior to traditional LMWH due to better compliance and safety. Apixaban has the most favorable pharmacokinetic and safety profile.

• A recommended protocol of Apixaban 2.5 mg twice daily from postoperative day 3 for one month is safe, effective, and patient-friendly.

• Successful implementation of these pathways is a multidisciplinary effort that improves patient safety, accelerates recovery, and enables trends like outpatient surgery.

MULTIPLE CHOICE QUESTIONS (MCQs)

1. What is the primary goal of the B-STOP protocol?

   a) To mandate a 3-day hospital stay.

   b) To reduce opioid use after bariatric surgery.

   c) To increase the use of epidural analgesia.

   d) To eliminate preoperative carbohydrate loading.

2. According to the lecture, which bariatric procedure most significantly impairs the absorption of Rivaroxaban?

   a) Sleeve Gastrectomy

   b) Laparoscopic Adjustable Gastric Banding

   c) Roux-en-Y Gastric Bypass

   d) One-Anastomosis Gastric Bypass

3. The intraoperative autonomic blockade for sleeve gastrectomy targets which two neural structures?

   a) The phrenic nerve and intercostal nerves.

   b) The vagus nerve and the celiac plexus.

   c) The splanchnic nerves and the superior mesenteric plexus.

   d) The rectus sheath and the obturator nerve.

4. What is the recommended timing for initiating Apixaban in the presented VTE prophylaxis protocol?

   a) 12 hours preoperatively.

   b) Immediately post-surgery.

   c) On postoperative day 3.

   d) One week after discharge.

5. Deep neuromuscular blockade monitored by TOF is crucial for enabling which intraoperative condition?

   a) Rapid sequence induction.

   b) Surgery at lower pneumoperitoneum pressures.

   c) The use of total intravenous anesthesia.

   d) Prevention of postoperative cognitive dysfunction.

6. According to the lecture, what is "reactive thrombosis"?

   a) A thrombosis occurring at the surgical site.

   b) A clot forming despite being on anticoagulation.

   c) A rebound hypercoagulable state after stopping LMWH.

   d) A thrombosis caused by an allergic reaction to heparin.

7. Which regional anesthetic technique is considered less effective for bariatric surgery because it primarily covers somatic pain?

   a) Erector Spinae Plane (ESP) block

   b) Paraganglionic block

   c) Intraoperative autonomic blockade

   d) Transversus Abdominis Plane (TAP) block

8. What is the recommended minimum duration for smoking cessation prior to bariatric surgery?

   a) 48 hours

   b) One week

   c) One month

   d) Six months

9. Which DOAC is described as having its absorption least affected by bariatric surgery, making it a reliable choice?

   a) Rivaroxaban

   b) Apixaban

   c) Dabigatran

   d) Edoxaban

10. What is the proposed mechanism by which vagal nerve blockade reduces nausea and epigastric pressure?

    a) Increasing gastric acid secretion.

    b) Decreasing gastric sleeve muscular tone and intraluminal pressure.

    c) Accelerating the rate of gastric emptying.

    d) Blocking pain signals from the diaphragm.

11. According to the ENERGY trial, ERAS protocols in bariatric surgery led to what percentage reduction in opioid use?

    a) 10%

    b) 20%

    c) 40%

    d) 60%

12. The recommended dose of Apixaban for extended VTE prophylaxis in the speaker’s protocol is:

    a) 5 mg once daily.

    b) 5 mg twice daily.

    c) 2.5 mg once daily.

    d) 2.5 mg twice daily.

13. Use of intraoperative ketamine is mentioned as being particularly useful for which patient population?

    a) Patients with severe sleep apnea.

    b) Patients with chronic pain.

    c) All sleeve gastrectomy patients.

    d) Patients with a BMI over 60.

14. To reduce aspiration risk, it is recommended to stop GLP-1 agonists for what duration before surgery?

    a) 24 hours

    b) 3 days

    c) Approximately two weeks

    d) One month

15. What is the leading cause of mortality following bariatric surgery?

    a) Anastomotic leak

    b) Myocardial infarction

    c) Pulmonary embolism

    d) Surgical site infection

16. What is the most critical safety check before injecting the anesthetic solution during an autonomic blockade?

    a) Checking the patient's blood pressure.

    b) Aspirating to ensure the needle is not in a vessel.

    c) Confirming the dose with the anesthesiologist.

    d) Warming the solution to body temperature.

17. Maintaining Mean Arterial Pressure (MAP) above which threshold is critical to minimize acute kidney and myocardial injury?

    a) 50-55 mmHg

    b) 60-65 mmHg

    c) 70-75 mmHg

    d) 80-85 mmHg

18. What is the recommended fasting guideline for clear liquids before anesthesia induction in an ERAS pathway for a patient without severe reflux?

    a) 8 hours

    b) 6 hours

    c) 4 hours

    d) 2 hours

19. The autonomic blockade technique provides effective analgesia for approximately how long postoperatively?

    a) 4-6 hours

    b) 8-12 hours

    c) 18-20 hours

    d) 48-72 hours

20. What is the primary management for a bariatric patient with known OSA in the postoperative period?

    a) They should avoid using their CPAP machine in the hospital.

    b) They should be kept on high-flow nasal cannula only.

    c) They should bring and use their home CPAP machine.

    d) They require mandatory ICU monitoring for 48 hours.

MCQ Answers: 1(b), 2(c), 3(b), 4(c), 5(b), 6(c), 7(d), 8(c), 9(b), 10(b), 11(c), 12(d), 13(b), 14(c), 15(c), 16(b), 17(b), 18(d), 19(c), 20(c)

MOTIVATIONAL MESSAGE FROM DR. R. K. MISHRA

The surgeon's greatest virtue is not speed, but foresight. It is the wisdom to anticipate, the discipline to prepare, and the humility to constantly refine your understanding of the patient before you.

I wish you clarity of thought and steadiness of hand as you continue your commitment to this demanding and rewarding discipline.