Context-Sensitive Airway Management

Abstract

The case presented by Mathew et al. in this issue of Anesthesia & Analgesia presents us with an opportunity to explore a broader view of difficult airway management: first, how a situation or context influences our approach to the problem; second, the “unwritten truth” of bronchoscopic intubation; and third, the importance of gas-exchange preservation over devices and techniques. In Chinese, the written word for “crisis,” “Wei Ji,” is formed by combining 2 separate words: “Wei” or “danger” and “Ji” or “opportunity.” This combination most likely originated from ancient teachings about how to live a life that thrives while responding to unpredictable mystical, political, and environmental forces. This frame of reference reflects a deep-seated philosophy of cultural survival. History provides a unique context that has resonance and reverberations in this day and age. In other words, although what we do today is often shaped by history and guided by evidence, our actions are frequently tempered by the circumstances (or “context”) in which we act. It has been said that we are in the midst of a medical-legal “crisis.” Perhaps, as the ancient Chinese did, we ought to seize this as an “opportunity,” though alert to the “danger” posed by this “crisis.” But in this modern context, the “opportunity” is shaped by evidence rather than mystical, environmental, and political forces. Caplan et al. first reported alarmingly poor outcomes related to the management of the difficult airway in their review of the American Society of Anesthesiologists (ASA) closed claims database in 1990. They reported that adverse outcomes associated with respiratory events constituted the single largest class of injury, and litigation, in anesthesia in the United States (34%). The review also identified that most of these airway management–related adverse respiratory outcomes were preventable. Recognizing that reversing this finding was paramount to our specialty, the ASA formed a task force to review the existing evidence and to recommend corrective airway management strategies. The ASA Difficult Airway Algorithm and Guidelines were published in 1993 and subsequently revised in 2003. Although there are limitations to the recommendations, the ASA guidelines provide clinicians with an evidence-based approach to the airway evaluation and management of patients about to undergo an anesthetic. Although it is difficult to assess the true impact of these guidelines on clinical outcomes, a recent review of the closed claims database showed that there are signs of improvement, with reduction in the number of adverse events (especially death and brain death) associated with airway management misadventures. Unfortunately, this improvement was limited to the management of the airway on induction of anesthesia, but not outside the operating room. Clearly, continuing efforts to increase awareness of the difficult airway and improve airway assessment and education, coupled with the enhancement of predictive and management strategies, are crucial to the difficult airway management approach in a controlled environment. The findings of Peterson et al. also suggest that a broader understanding and approach to airway management is needed to improve overall outcome. During the last 2 decades, many new airway devices and techniques have been developed, and these have changed the landscape of airway practice and management. In addition, there has been a major paradigm shift in airway management, emphasizing gas exchange (ventilation and oxygenation) over tracheal intubation. Clinicians use only 4 methods of ventilation and oxygenation: a bag mask, an extraglottic device (e.g., a laryngeal mask airway), a tracheal tube, and a surgical airway. Selection of one of these techniques to provide gas exchange depends not only on the devices best suited to the patient’s anatomy but also on the situation faced by the clinician. In other words, airway management is “context sensitive” in that it is heavily dependent on the clinical situation and the environment. If, for instance, a patient presents with a history or clinical features predictive of an “impossible” tracheal intubation using a laryngoscope, and also possesses predictors of difficult bag-mask ventilation and difficulty in using an extraglottic device, such as the laryngeal mask airway, it would be prudent for the clinician in the setting of an operating room to secure the airway awake, frequently utilizing a flexible fiberoptic bronchoscope. However, the management plan would be quite different if this same patient required airway management in the prehospital setting, in the emergency department, or in the magnetic resonance imaging suite where skill sets and limited resources play decisive roles. The selection of an airway approach might also be different if the patient requires immediate and rapid emergency airway intervention, if the patient is a small child who is extremely uncooperative, or if the patient is pregnant. There are From the Department of Anesthesia, Dalhousie University, Queen Elizabeth II Health Sciences Centre, Halifax, Nova Scotia, Canada.