This is a case of an impending TAA rupture, complicated by esophageal stenosis with a significant amount of food residues, and hypoxia due to compression of the pulmonary artery and left bronchi. This patient had a high risk of aspiration because fasting had not been observed, and she developed esophageal stenosis resulting from residual food particles [3]. Moreover, the patient experienced hypoxia before anesthetic induction. During anesthesia induction, pulmonary aspiration, development of hypoxemia, and rapid hemodynamic changes that may lead to rupture were avoided. To achieve this, endotracheal intubation with a superior laryngeal nerve block was performed while the patient was awake under light sedation.
The common options for anesthesia induction in patients at risk of pulmonary aspiration include awake endotracheal intubation, and rapid sequence induction and intubation (RSII). During awake intubation, the patient can spit out the aspirated contents. Furthermore, awake intubation with oxygenation preserves spontaneous breathing and prevents hypoxia development [4]. In contrast, RSII can possibly increase the morbidity and mortality of patients with hypoxia [5,6,7]. Thus, awake intubation was performed in this patient.
Although the patient came to the hospital within 3 h from the onset of her symptoms, CT revealed signs of an impending rupture. This implied the rapid enlargement of the TAA and its near rupture. Therefore, the risk of rupture was considerably high. To prevent hemodynamic changes that may lead to rupture during intubation, light sedation was performed with intravenous administration of midazolam and fentanyl. A superior laryngeal nerve block was also conducted, and antihypertensives were administered. Previous case reports have documented successful awake intubation procedures with the use of a superior laryngeal nerve block [8]. The superior laryngeal nerve, a branch of the vagal nerve, provides sensory input from the lower pharynx and upper larynx, including the glottic surface of the epiglottis and the aryepiglottic folds [2]. The block decreases sensory inputs from the lower pharynx and upper larynx. This may contribute to the suppression of noxious stimuli that may cause rupture during intubation. However, there is an increased risk of aspiration because the block inhibits the deglutition reflex. This is circumvented by performing awake intubation, wherein the patient can spit out aspirated contents.
According to the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists guidelines [9], intubation was absolutely contraindicated in the present case due to the possibility of esophageal perforation secondary to esophageal stenosis. Esophageal stenosis due to TAA was observed in this patient. Thus, performing TEE would have caused esophageal perforation. Since the TAA with an impending rupture was located at the esophageal border, the TEE insertion could have caused TAA rupture.
In summary, this was a case of an impending TAA rupture, causing esophageal stenosis and hypoxia due to compression of the pulmonary artery and left bronchi. Performing awake endotracheal intubation with a superior laryngeal nerve block and light sedation effectively prevented food residue aspiration, hypoxia development, and hemodynamic changes that could have led to rupture in the present case. TEE probes should not be inserted in esophageal stenosis cases due to giant TAAs.