On a Saturday morning, a 42-year-old male presents to the operating room for an urgent cystoscopy to remove a high ureteric stone. He is a smoker and has no known allergies. He has been taking subcutaneous hydromorphone for renal colic for several days as an inpatient, with little relief. He has had numerous uneventful previous cystoscopy and extracorporeal shock wave lithotripsy (ESWL) procedures in the past for nephrolithiasis. His last general anesthetic for a cystoscopy 6 months ago was completed uneventfully after the insertion of a LMA-Classic #5. He has been appropriately fasted for 8 hours when he arrives in the operating room.

The patient’s cardiovascular and respiratory examination is unremarkable, his vital signs are stable and he is afebrile. The urology team does not feel that the patient has urosepsis at this time. His BMI is 27.3 kg·m⁻². His airway exam is normal with no predictors of difficulties in bag-mask-ventilation (BMV), use of extraglottic devices (EGDs), tracheal intubation, or surgical airway.

He has a #18-gauge IV catheter in situ in his left forearm. Following denitrogenation, general anesthesia is induced with midazolam 1 mg IV, fentanyl 50 mcg IV, and propofol 250 mg IV. Immediately after propofol administration and as the patient loses consciousness, he complains of pain at the IV site, and bile-colored fluid leaks around the face mask. Projectile vomitus occurs when the face mask is removed. After suctioning the oropharynx in Trendelenburg position, oxygen saturation rapidly decreases to 80%, and there is an audible wheeze. Swelling is noted at the IV site and the gravity feed IV is no longer dripping.

Aspiration of gastric contents is still an important cause of morbidity and mortality associated with airway management. Aspiration was the most common cause of death in anesthesia cases reported to the Fourth National Audit Project—Major complications of airway management in the UK: Results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society (NAP4). This report, published in 2011, illustrated that aspiration is not simply a historical anesthesia complication.¹ Events in which death occurred were associated with significant hypoxemia and brain damage following aspiration.

The incidence of aspiration during anesthesia has been widely estimated, and this is reviewed in Chapter 5. One in five of all NAP4 anesthesia reports described aspiration of gastric contents as a primary or secondary event (17% and 5% respectively). In addition, many aspiration event survivors had prolonged intensive care stays. Common themes were incomplete assessment of aspiration risk and failure to alter the anesthetic technique when aspiration risk was present.

Great care is taken to discuss pre-induction preparation for prevention of aspiration in airway algorithms, but interestingly, little attention is given to management of ongoing aspiration in the setting of a “cannot intubate, cannot oxygenate” (CICO) difficult airway, and the subsequent management of such events.

This case and chapter will highlight the priorities of: (1) oxygenation; (2) prevention of further pulmonary aspiration of gastric contents; and (3) management of a patient who has experienced an aspiration event in the context of a difficult airway.

Is This Patient at High Risk of Aspiration?

Risk factors for pulmonary aspiration of gastric contents are well described in Chapter 5, with emergency surgery being the most important.² Some methods, although not universally accepted, can be used to decrease the risk and minimize complications associated with aspiration.¹ These include: (1) performance of regional anesthesia and avoidance of general anesthesia; (2) appropriate pre-induction fasting; (3) appropriate nasogastric tube insertion and drainage of gastric contents; (4) premedication with prokinetic medications, antacids, H₂-blockers, and proton pump inhibitors; (5) tracheal intubation; (6) use of rapid sequence intubation or awake intubation when appropriate; and (7) use of a second-generation EGD.

This patient had received many general anesthetics with a first-generation EGD used as the primary airway device with no previously documented complications. It is important to realize that airway management is context specific, and there may be new patient or situational factors that will require alteration of the anesthetic plan.

Difficult intubation is associated with an increased risk of aspiration. This risk of regurgitation and subsequent aspiration increases exponentially with intubation attempts.^3,4 Coughing or gagging with airway interventions also increases the risk of aspiration,^5–7 and light anesthesia combined with the absence of muscle paralysis when placing the EGD, may have placed this patient at an increased risk of aspiration.

The patient had been receiving parenteral opioid medications for several days prior to presenting to the operating room. This is an important risk factor to consider, as opioids have been shown to significantly decrease gastric emptying.⁸

Appropriate patient selection for EGD use is essential. Whereas it is quite obvious that an alternate method of airway control should be considered in patients at high risk of aspiration, multiple contributing risk factors may create the conditions required for a clinically significant aspiration event. When comparing this case to those reported in NAP4, potential considerations for not using an EGD in this patient would include the culmination of recent opioid use, pain, potential for ileus, and the requirement of the lithotomy position. Given the multitude of risk factors for aspiration,⁹ the airway practitioner must determine the level of risk for aspiration when choosing an airway management strategy.

Although EGDs have a documented safety profile in appropriately selected patients and cases, published case reports and series continue to highlight the morbidity and mortality associated with aspiration and EGD use.^10–13

How Do You Diagnose Aspiration of Gastric Contents?

As reviewed in Chapter 5, a diagnosis of aspiration cannot be made by the presence of gastric material in the oropharynx alone. Given that this patient is now symptomatic with hypoxemia and an audible wheeze, the airway practitioner must have a high index of suspicion for aspiration. This patient requires simultaneous airway management and plans for further treatment of the aspiration event.

Pulmonary aspiration of gastric contents is generally defined as either the presence of bilious secretions or particulate matter in the tracheobronchial tree or, if bronchoscopy is not performed, infiltrates present on a postoperative chest radiograph together with physical examination findings.² Sequelae range in severity from mild symptoms, such as hypoxemia, to respiratory failure, acute respiratory distress syndrome (ARDS), cardiovascular collapse, anoxic brain injury, and death.¹⁴ Review of these clinical syndromes in relation to this case will highlight the management of an aspiration event in a patient with a difficult airway.

When this patient vomited on induction, the appropriate measures were taken to prevent further aspiration. The head of the bed was immediately adjusted to a 30-degree Trendelenburg position, and the upper airway was suctioned. Prior to the vomiting, the patient received an induction dose of intravenous propofol, and awakening this symptomatic patient with no definitive airway and ongoing vomiting and aspiration was not a reasonable option. Ideally, the trachea of the patient would be intubated and receive tracheal suctioning before the initiation of positive pressure ventilation.

Aspirated gastric contents, such as fluid or other foreign body material, can cause airway obstruction, laryngospasm, or distal airway closure. This may precipitate hypoxemia, pulmonary edema, reduced lung compliance, bronchospasm, and atelectasis. The clinical consequences will depend on the location of obstruction and the amount and characteristics of the aspirated material. Primary treatment for these events is generally removal of the foreign body and respiratory and cardiovascular support.

Aspiration, and its associated complications, makes the management of an unanticipated difficult airway more challenging. The onset of symptoms associated with aspiration of gastric contents can be rapid, and damage can occur within seconds. First described by Mendelson,¹⁵ chemical pneumonitis can be associated with significant cyanosis and ARDS. Extrapolation from animal studies concluded that aspirate with a pH less than 2.5 and a volume of 25 mL or more correlated with aspiration and resultant pneumonitis.¹⁶ Pathological lung changes evolve rapidly due to the rapid immunological response to the chemical injury. Pulmonary edema, hemorrhage, and consolidation lead to decreased lung compliance, abnormal ventilation perfusion, and decreased diffusion capacity causing severe hypoxemia. Respiratory support, in the form of mechanical ventilation, is the primary therapeutic approach for these patients.

How Do You Proceed with This Case?

The prevention of pulmonary aspiration of gastric contents is a significant concern for the airway practitioner and focuses prominently in all the difficult airway management algorithms.^17–20 There is, however, no discussion of the steps to follow if regurgitation and aspiration occur during the management of the difficult airway.

Management of the Unanticipated Difficult Airway During Active Aspiration

A call for help and the difficult airway cart is made. Unfortunately, limited assistance is available because it is Saturday. An LMA-Classic #4 was the planned airway for the surgical procedure and equipment and drugs to facilitate tracheal intubation are not ready. In the presence of deteriorating oxygen saturation, the airway practitioner proceeds to use BMV. Unfortunately, the patient’s oxygen saturation does not improve from 80% using BMV with an oropharyngeal airway and an FiO₂ 1.0 with a reasonable capnography trace. The decision is made to intubate the trachea for airway protection, bronchoscopic assessment, and suctioning. After a new #18-gauge IV catheter is secured (by the urologist), 100 mg of propofol and 100 mg of succinylcholine are administered and direct laryngoscopy is performed with the Macintosh #4 laryngoscope. Difficulty is encountered with direct laryngoscopy because of poor head and neck position on the fluoroscopy table. An intubation attempt with the GlideScope also proves difficult, and the oxygen saturation now decreases to 50%.

An LMA-Classic #4 is placed with ease, and the oxygen saturation returns to around 85%. A definitive airway is required and the airway practitioner prepares for intubation through the LMA-Classic. Despite suctioning, tracheal intubation using the pediatric flexible bronchoscope (FB) with an ensleeved Aintree catheter (Cook Critical Care, Bloomington, IN) via the LMA is difficult because of blood and secretions in the airway. Eventually, the tip of the FB is advanced into the trachea and positioned close to carina. The Aintree catheter is advanced to the tip of the bronchoscope and the FB removed. The LMA is then removed and the endotracheal tube (ETT) is advanced easily over the Aintree. On manual ventilation through the ETT no carbon dioxide (CO₂) is detected and the oxygen saturation rapidly drops to 55%. The ETT is quickly removed, and an LMA-Classic #4 is reinserted. Oxygen saturation improves to 85%.

How Do You Manage the Airway of a “Can’t Intubate But Can Barely Oxygenate” Patient with Gastric Aspiration?

Oxygenation must be the priority while managing a patient with a difficult airway in the setting of aspiration. While an EGD is less than an ideal airway device in a patient who has aspirated gastric contents, it allows the airway practitioner to oxygenate the patient while making preparations for definitive airway management. This is especially important with this case, given that tracheal intubation had not been successful under direct or video-laryngoscopy. When reviewing this case, it could be suggested that a second-generation EGD should have been inserted instead of a first-generation EGD. Theoretically, waking up a patient such as this without securing the airway could be considered, but ongoing low-oxygen saturations with episodes of further rapid desaturation and the immediate need for pulmonary toilet and ventilator support precluded this option. In addition, this patient is at risk to have more regurgitation and aspiration on emergence.

An ENT surgeon is consulted for the performance of a tracheotomy. The tracheotomy is difficult but a #6 Shiley tracheostomy tube (Medtronic, Minneapolis, MN) is successfully placed. The patient’s oxygen saturation improved to 95% with manual ventilation and a fraction of inspired oxygen (FiO₂) of 100%. After communication with the intensive care unit (ICU) attending physician, arrangements were made to transport the patient to the ICU for postoperative monitoring and management.

Is Tracheotomy Necessary for This Patient?

Tracheotomy is commonly performed in critically ill patients who require prolonged mechanical ventilation for acute respiratory failure, neurological insult, and for airway issues.²¹ Indications for tracheotomy include upper airway obstruction, requirement of prolonged ventilation, facilitation of weaning from mechanical ventilation, airway protection, and secretion removal. Upper airway obstruction is a less common indication for tracheotomy.

There is limited literature to support best practice in management of a CICO patient who has also aspirated.^22,23 The patient in this case has both acute respiratory distress from the gastric aspiration and inadequate oxygenation through the EGD. The patient’s airway is not protected from further aspiration with the currently inserted first-generation EGD. Given the context of this unanticipated CICO situation and the requirement of a definitive airway for mechanical ventilation and airway protection, the decision to perform a tracheotomy was made.

It should be emphasized that the surgical airway cannot be considered as “a failure,” but rather an alternative method to oxygenate a patient when other methods have failed. A surgical airway is one of the four essential methods to provide ventilation and oxygenation, however airway practitioners are often reluctant to perform a surgical airway and many may even consider it a failure at critical moments, such as in “can’t intubate, can’t oxygenate” situations. According to the closed claims analysis report, Peterson et al.²⁴ reported that two-third of the patients who died or had brain damage had a surgical airway, but the procedure was performed too late. The investigators suggested that “For a surgical airway to be successful as a rescue option, it must be instituted early in the management of the difficult airway. Prompt calls for the appropriate equipment and personnel may save lives.”