Anesthetic Complications: Airway Injury

AIRWAY INJURY

The daily insertion of endotracheal tubes, laryn-geal mask airways, oral/nasal airways, gastric tubes, transesophageal echocardiogram (TEE) probes, esophageal (bougie) dilators, and emergency air-ways all involve the risk of airway structure damage. Common morbid complaints, such as sore throat and dysphagia, are usually self-limiting, but may also be nonspecific symptoms of more ominous complications.

The most common persisting airway injury is dental trauma. In a retrospective study of 600,000 surgical cases, the incidence of injury requiring den-tal intervention and repair was approximately 1 in 4500. In most cases, laryngoscopy and endotracheal intubation were involved, and the upper incisors were the most frequently injured. Major risk fac-tors for dental trauma included tracheal intubation, preexisting poor dentition, and patient character-istics associated with difficult airway management (including limited neck motion, previous head and neck surgery, craniofacial abnormalities, and a his-tory of difficult intubation).

Other types of airway trauma are rare. Although there are scattered case reports in the literature, the most comprehensive analysis was performed by the ASA Closed Claims Project. This report describes 266 claims, of which the least serious were temporo-mandibular joint (TMJ) injuries that were all asso-ciated with otherwise uncomplicated intubations and occurred mostly in females younger than age 60 years. Approximately 25% of these patients had previous TMJ disease. Laryngeal injuries included vocal cord paralysis, granuloma, and arytenoid dis-location. Most tracheal injuries were associated with emergency surgical tracheotomy, but a few were related to endotracheal intubation. Some injuries occurred during seemingly easy, routine intuba-tions. Proposed mechanisms include excessive tube movement in the trachea, excessive cuff inflation leading to pressure necrosis, and inadequate relax-ation. Esophageal perforations contributed to death in 5 of 13 patients. Esophageal perforation often presents with delayed-onset subcutaneous emphy-sema or pneumothorax, unexpected febrile state, and sepsis. Pharyngoesophageal perforation is asso-ciated with difficult intubation, age over 60 years, and female gender. As in tracheal perforation, signs and symptoms are often delayed in onset. Initial sore throat, cervical pain, and cough often progressed to fever, dysphagia, and dyspnea, as mediastinitis, abscess, or pneumonia develop. Mortality rates of up to 50% have been reported after esophageal per-foration, with better outcomes attributable to rapid detection and treatment.

Minimizing the risk of airway injury begins with the preoperative assessment. A thorough air-way examination will help to determine the risk for difficulty Documentation of current dentition (including dental work) should be included. Many practitioners believe preoperative consent should include a discussion of the risk of dental, oral, vocal cord, and esophageal trauma in every patient who could potentially need any airway manipulation. If a difficult airway is suspected, a more detailed dis-cussion of risks (eg, emergency tracheotomy) is appropriate. In such cases, emergency airway sup-plies and experienced help should be available. The ASA algorithm for difficult airway management is a useful guide. After a difficult intubation, one should seek latent signs of esophageal perforation and have an increased level of suspicion for airway trauma. When intubation cannot be accomplished by routine means, the patient or guardian should be informed to alert future anesthesia providers of potential air-way difficulty.

Emergent nonoperating room intubations pres-ent unique challenges. In a review of 3423 out of the operating room intubations, 10% were considered to be “difficult,” and 4% of these intubations were asso-ciated with some form of complication, including aspiration, esophageal intubation, or dental injury. In this report, intubation bougies were employed in 56% of difficult intubations. The increased availabil-ity of video laryngoscopes and bougies have made emergent intubations less stressful and less likely to be unsuccessful.