The Case

A 32-year-old woman with weight of 100.2 kg (body mass index of 39.1) with a history of gastroesophageal reflux disease (GERD), diabetes mellitus and obstructive sleep apnea (OSA) presented to an outpatient GI clinic with abnormal liver function tests, ultrasound findings consistent with cholelithiasis and clinical signs concerning for obstructive jaundice. She was admitted to the hospital and scheduled for endoscopic retrograde cholangiopancreatography (ERCP) as an inpatient procedure.

Monitored anesthesia care (MAC) was selected as the preferred choice for this patient. A continuous propofol infusion and fentanyl boluses were administered intravenously. Once an appropriate level of sedation was achieved, the patient was positioned prone. The procedure began with insertion of the endoscope after a bite block was placed. As the scope was advanced into the stomach, the patient vomited. She was immediately turned supine, and her airway was suctioned. Copious vomitus obstructed the suction catheter and was difficult to remove. The patient started to decompensate with decreasing oxygen saturation. The anesthesia team attempted to secure the airway by endotracheal intubation but was unable to place a tube due to poor view and vomitus. Several unsuccessful attempts at intubation were made. The patient went into cardiac arrest and cardiopulmonary resuscitation was initiated while the team attempted to secure the airway between compressions, without success. Appropriate doses of Advanced Cardiac Life Support (ACLS) medications were given. The airway was ultimately secured using a videolaryngoscope; return of spontaneous circulation (ROSC) was never achieved, and the patient was pronounced dead after 60 minutes of ACLS.

The Commentary

By Timothy Do, BS and Fiona J. Scott, MD, MPH, MS, MHI

Endoscopic retrograde cholangiopancreatography (ERCP) is often recommended for patients presenting with obstructive jaundice and concern for choledocholithiasis, as it may serve both diagnostic and therapeutic goals. ERCP can be performed either as an outpatient or inpatient procedure, depending on patient’s presentation, urgency of the procedure, and available resources. ERCPs have become common, utilizing endoscopic fluoroscopy to visualize and access the biliary and pancreatic ducts.¹

The rates of hospitalization of patients presenting with choledocholithiasis has increased across the United States over the past 20 years,² which could possibly be due to the rise of metabolic syndrome and sedentary lifestyle leading to gallstone formation, amongst other factors. Although there has been debate regarding ERCP compared with other treatment options, it remains a commonly performed procedure.

Patients requiring ERCP procedures often have several comorbidities that must be considered when planning for anesthesia. As in the case above, many patients presenting for ERCP have risk factors for aspiration in the perioperative period. In this scenario, the patient had obesity, GERD, and diabetes, all of which increase the risk of aspiration.³ Additionally, her fasting status was unknown. Other factors commonly found in patients presenting for ECRP with an increased aspiration risk include non-fasting status, use of glucagon-like peptide 1 (GLP-1) agonists, stricture or other factors contributing to delayed gastric emptying. Other factors that increase aspiration risk include full stomach, incompetent lower esophageal sphincter, and esophageal diseases. Surgical factors can also increase the risk of aspiration including head-down positioning and certain types of operations, such as upper gastrointestinal surgery, laparoscopic surgery, and cholecystectomy. Anesthetic factors such as difficult intubation, light anesthesia, prolonged surgery duration, or positive pressure ventilation can also contribute to this risk.

Before proceeding with an ERCP case, the anesthesiologist must consider what choice of anesthetic is best for the patient given the patient’s comorbid conditions, anesthetic history, anticipated positioning, and the urgency of the procedure. A complete airway exam should be completed in addition to a cardiopulmonary exam. Authors in the literature have debated the choice of anesthetic for ERCP. According to one randomized trial comparing MAC vs. general anesthesia (GA) for ERCP, significantly more sedation-related adverse events were found with patients under MAC vs. GA.⁴ The risk of intraprocedural hypoxemia, hypercapnia, and apnea is greater with MAC compared to GA with tracheal intubation.⁵ According to the authors of this study, MAC is preferred if procedures are short, diagnostic, and allow for rapid patient recovery.⁵ MAC may also offer benefit if patients have cardiorespiratory risk factors such as recent myocardial infarction, chronic lung disease, asthma, and ASA (American Society of Anesthesiology) score >3. GA is preferred for patients with gastric outlet obstruction, prolonged procedures with risk of hypoventilation or perforation, and procedures with high risk of gastrointestinal bleeding.⁵ However, several other studies failed to show any difference in ERCP outcomes for MAC vs. GA.^6,7 Anesthesiologists need to thoroughly evaluate the patient’s comorbidities and procedural-related factors in determining the safest course of action. With either MAC or GA considered to be an acceptable choice, and no currently standardized guidelines, the decision must be made in the context of the individual patient’s needs.^6,8 Different levels of sedation (minimal, moderate, deep, and general anesthesia) are defined by the American Society of Anesthesiologists (ASA). MAC can include all levels of sedation and patients may need airway intervention if deep sedation is achieved.⁹ No matter which form of anesthesia is used, emergency airway equipment and appropriate medications must be readily available at all times.

Preventing Aspiration

Aspiration is a feared complication of anesthesia. There are many strategies that an anesthesia care provider can employ to reduce the risk of aspiration during procedures. Some preemptive measures include thorough preoperative risk assessment and preoperative fasting. It is essential to ensure appropriate gastric emptying before proceeding with ERCP, to minimize the risk of aspiration. If the case is emergent/urgent and there is insufficient fasting time, then rapid sequence intubation (RSI) with endotracheal intubation is likely the safest option to minimize the risk of aspiration while securing the airway.¹⁰ Even if appropriate fasting times have been observed, one must not assume the patient has an empty stomach, particularly with the increasing use of GLP-1 agonists. Additional steps should be considered to confirm there are minimal contents in the stomach including supine and lateral gastric ultrasound or esophagogastroduodenoscopy (EGD) immediately before ERCP to confirm that the stomach is empty.

Preemptive nasogastric tube placement has been proposed as an option to reduce aspiration risk, but evidence to support this practice is lacking.¹¹ In this case, the addition of a nasogastric tube during ERCP may have increased the risk of injury, increased patient discomfort, and in retrospect would have had limited utility for larger food particles. Histamine antagonists, proton pump inhibitors, and prokinetics have been proposed in the past to reduce aspiration risk but are not currently recommended by the American Society of Anesthesiologists.¹²

Patient Positioning

The patient’s position can play an integral role in the kind of anesthesia and airway management deemed appropriate. Prone positioning can be beneficial in aspiration as gastric contents are directed away from the lungs; however, should an artificial airway be needed, prone positioning can make insertion more difficult. In contrast, supine positioning allows for easier endotracheal intubation, but it is associated with increased risk of pulmonary aspiration.¹³ In this case, the patient was in the prone position, which may have reduced her risk of aspiration, but immediately turning her supine may have increased the volume of aspirated vomitus. If feasible, an aspirating patient who is aspirating should be placed head down and suctioned in the prone position to allow for removal of vomitus before turning the patient supine. According to prior simulation studies,^14,15 supine position with a head-down tilt and full cervical spine extension facilitates the drainage of liquids away from the larynx to prevent aspiration. Although this position demonstrated less aspirated fluid, neck flexion and head extension (e.g., the “sniffing” position) remains the most commonly used position for endotracheal intubation.¹⁶ On average, the median time to intubate is longer in the head-down tilt with full cervical spine extension than in the more commonly used sniffing position.¹⁵ In this case, one cannot determine whether the patient should have been placed in a head-down tilt with full cervical spine extension or sniffing position. Minimizing aspiration was crucial, yet there was a constrained timeframe to secure the airway, which was equally vital in efforts to prevent her demise.

Management of Aspiration

After an intraoperative pulmonary aspiration event, the immediate recognition of aspiration is integral to successful management. In addition to visualization of gastric contents in the mouth or airway, other signs of aspiration include persistent hypoxia, high airway pressures, bronchospasm, or abnormal breath sounds.¹¹ The patient should be positioned with the head down and rotated laterally to minimize aspiration. During this case, orotracheal and endotracheal suctioning would also be indicated. If possible, the endoscope should be utilized to remove vomitus before its withdrawal.^11,17 Large bore Yankauer suction catheters can be helpful to remove large food residuals from the oropharynx or esophageal introitus. They can also be placed in the proximal esophagus while intubating or during ongoing CPR if passive aspiration is occurring. In this case, it might have been possible for the patient to return to spontaneous ventilation with the return of her own protective airway reflexes. Returning the patient to spontaneous ventilation would potentially limit ongoing aspiration and obviate the need for further intubation attempts. It is not known what level sedation was achieved during the procedure; however, the anesthetic should have been immediately discontinued and Narcan given. Additionally, the patient should be stimulated with a jaw thrust and verbal prompting to assess her level of sedation and the feasibility to return to spontaneous ventilation. If prompt resumption of spontaneous ventilation was deemed not possible and the patient was unresponsive or rapidly deteriorating, then rapid sequence intubation medications including a paralytic could be administered immediately while securing the airway.

Difficult Airway

The Difficult Airway Algorithm outlined in the 2022 American Society of Anesthesiologists Guidelines provides useful guidance in any situation where ventilating the patient is not possible and securing the airway fails (algorithm figure available here).¹⁸ In this case, vomitus obstructed the view of the airway and in all likelihood, the resuscitation attempts made securing the airway more difficult. Given that this case represented a respiratory arrest, as opposed to a cardiac event (given known aspiration), rapid establishment of a secure airway and the delivery of oxygen to tissues is crucial to decreasing mortality.

To secure the airway, the patient should be turned supine as was done in this case. A call for additional help via an overhead paging system (e.g., “code blue”) is critical to have extra hands in this emergency. The patient should be supplied with 100% FiO₂ via bag mask and airway adjunct (oropharyngeal/nasopharyngeal airway) while preparing for an emergency airway. In the setting of an obese patient who has vomited, two hand mask ventilation technique is likely needed. Positive pressure mask ventilation for an aspirating patient is not ideal due to the risk of pushing aspirate further into the airway, but it may be unavoidable in this critical situation especially when endotracheal intubation cannot be accomplished quickly. The oropharynx must be continually suctioned and often two suction catheters may be needed. The use of laryngeal mask airway (LMA) is part of the emergency airway algorithm, and its use can facilitate ventilation of the patient in cases where endotracheal intubation is difficult and can also be utilized to facilitate intubation through an intubating LMA.¹⁹ Other emergency airway devices including a video laryngoscope and fiberoptic scope may also be helpful. Using these devices can be difficult in the setting of aspiration, as the camera view can quickly become obscured. The emergency airway algorithm dictates that “alternative intubation approaches” be attempted, including laryngeal mask airway.

It must also be noted that the last resort in the emergency airway algorithm is performing an emergency invasive airway. All attempts to secure an airway in an emergency must be made, including performing a surgical airway. Surgical airway kits are part of the emergency medical equipment that should be available and checked daily by the anesthesiologist. In this case, no attempt at surgical airway was made. The patient suffered from a severe aspiration event, which most likely led to asphyxiation and severe hypoxia resulting in cardiopulmonary arrest and death.

Take Home Points

• The stomach must be empty prior to proceeding with ERCP under MAC. Fasting time alone is not enough to confirm this. Gastric ultrasound may be useful. Confirm gastric emptying with the ERCP endoscope prior to proceeding.
• The choice of monitored anesthesia care vs general anesthesia with endotracheal intubation must be carefully considered in procedures such as ECRP, taking into account the risks and benefits based on each patient’s preferences, comorbid conditions, and physiology.
• Suction a prone patient who is aspirating in the head-down position prior to turning supine if able to do so.
• Call for help in an emergency and proceed down the emergency airway algorithm.
• Ventilate the patient who has aspirated with 100% oxygen, utilizing airway adjuncts including LMAs as needed

Timothy Do, BS
School of Medicine
UC Davis Health
timdo@ucdavis.edu

Fiona J Scott, MD, MPH, MS, MHI
Assistant Professor
Department of Anesthesiology and Pain Medicine
UC Davis Health
fjscott@ucdavis.edu

References

1. ASGE Standards of Practice Committee, Maple JT, Ben-Menachem T, et al. The role of endoscopy in the evaluation of suspected choledocholithiasis. Gastrointest Endosc. 2010;71(1):1-9. [Free full text]
2. Li S, Guizzetti L, Ma C, et al. Epidemiology and outcomes of choledocholithiasis and cholangitis in the United States: trends and urban-rural variations. BMC Gastroenterol. 2023;23(1):254. [Free full text]
3. Khan A, Kim A, Sanossian C, et al. Impact of obesity treatment on gastroesophageal reflux disease. World J Gastroenterol. 2016;22(4):1627-1638. [Free full text]
4. Alzanbagi AB, Jilani TL, Qureshi LA, et al. Randomized trial comparing general anesthesia with anesthesiologist-administered deep sedation for ERCP in average-risk patients. Gastrointest Endosc. 2022;96(6):983-990.e2. [Free full text]
5. Azimaraghi O, Bilal M, Amornyotin S, et al. Consensus guidelines for the perioperative management of patients undergoing endoscopic retrograde cholangiopancreatography. Br J Anaesth. 2023;130(6):763-772. [Available at]
6. Dhaliwal A, Dhindsa BS, Saghir SM, et al. Choice of sedation in endoscopic retrograde cholangiopancreatography: is monitored anesthesia care as safe as general anesthesia? A systematic review and meta-analysis. Ann Gastroenterol. 2021;34(6):879-887. [Free full text]
7. McCarty TR, Hathorn KE, Creighton DW, et al. Safety and sedation-associated adverse event reporting among patients undergoing endoscopic cholangiopancreatography: a comparative systematic review and meta-analysis. Surg Endosc. 2021;35(12):6977-6989. [Free full text]
8. Janik LS, Stamper S, Vender JS, et al. Pro-con debate: monitored anesthesia care versus general endotracheal anesthesia for endoscopic retrograde cholangiopancreatography. Anesth Analg. 2022;134(6):1192-1200. [Free full text]
9. Blayney MR. Procedural sedation for adult patients: an overview. Continuing Education in Anaesthesia Critical Care & Pain. 2012;12(4):176-180. [Free full text]
10. Wallace, C, McGuire B. Rapid sequence induction: its place in modern anesthesia. Continuing Education in Anaesthesia Critical Care & Pain. 2014;14(3):130-135. [Free full text]
11. Nason KS. Acute Intraoperative Pulmonary Aspiration. Thorac Surg Clin. 2015;25(3):301-307. [Free full text]
12. American Society of Anesthesiologists Committee. Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: application to healthy patients undergoing elective procedures: an updated report by the American Society of Anesthesiologists Committee on Standards and Practice Parameters. Anesthesiology. 2011;114(3):495-511. [Free full text]
13. Green SM, Mason KP, Krauss BS. Pulmonary aspiration during procedural sedation: a comprehensive systematic review. Br J Anaesth. 2017;118(3):344-354. [Free full text]
14. Takenaka I, Aoyama K, Iwagaki T. Combining head-neck position and head-down tilt to prevent pulmonary aspiration of gastric contents during induction of anaesthesia: a volunteer and manikin study. Eur J Anaesthesiol. 2012;29(8):380-385. [Free full text]
15. St Pierre M, Krischke F, Luetcke B, et al. The influence of different patient positions during rapid induction with severe regurgitation on the volume of aspirate and time to intubation: a prospective randomised manikin simulation study. BMC Anesthesiol. 2019;19(1):16. [Free full text]
16. Adnet F, Baillard C, Borron SW, et al. Randomized study comparing the "sniffing position" with simple head extension for laryngoscopic view in elective surgery patients. Anesthesiology. 2001;95(4):836-841. [Free full text]
17. Kalinowski CP, Kirsch JR. Strategies for prophylaxis and treatment for aspiration. Best Pract Res Clin Anaesthesiol. 2004;18(4):719-737. [Available at]
18. Apfelbaum JL, Hagberg CA, Connis RT, et al. 2022 American Society of Anesthesiologists Practice Guidelines for Management of the Difficult Airway. Anesthesiology. 2022;136(1):31-81. [Free full text]
19. Frappier J, Guenoun T, Journois D, et al. Airway management using the intubating laryngeal mask airway for the morbidly obese patient. Anesth Analg. 2003;96(5):1510-1515. [Free full text]