AIRWAY MANAGEMENT FOR PATIENTS WITH COVID-19 — In patients with novel coronavirus (COVID-19) disease, there is a high risk of aerosol spread of the virus during airway management procedures. To avoid such spread, certain practices used in standard rapid sequence intubation (RSI) must be modified. Techniques for improving patient care and minimizing infectious risks to care providers and spread of the virus during emergency intubation are summarized in the following table (table 1) and discussed in greater detail separately. A sample intubation checklist for patients with COVID-19 is also provided (figure 1). (See "COVID-19: Respiratory care of the nonintubated hypoxemic adult (supplemental oxygen, noninvasive ventilation, and intubation)", section on 'The decision to intubate'.)
INTRODUCTION — This topic review will discuss an algorithmic approach to advanced emergency airway management in adults. Other issues related to airway management, including basic airway management, difficult airway assessment, and rapid sequence intubation, are discussed in detail elsewhere. (See "Basic airway management in adults" and "Approach to the anatomically difficult airway in adults outside the operating room" and "Rapid sequence intubation for adults outside the operating room".)
BACKGROUND — Airway management is an essential skill for clinicians caring for critically ill or injured patients and is fundamental to the practice of emergency medicine. In emergency medicine practice, rapid sequence intubation (RSI) is the most frequently used and successful means of intubating the trachea [1,2]. It is employed in approximately 80 to 85 percent of all patients requiring intubation in academic emergency departments. Patients who arrive in cardiac arrest, who are intubated without medications, comprise the bulk of the remaining patients.
Although RSI is generally the preferred approach in the emergency department, even in patients with some anatomic difficulty, it may be poorly suited for some patients with profound difficult airway attributes, especially those with limited oral access or partial airway obstruction. Thus, a careful assessment for the type and degree of airway difficulty must precede the decision to use RSI [3,4].
RSI AND THE DIFFICULT AIRWAY — Clinicians should employ an approach to emergency airway management that accounts for the possibility of difficult intubation, difficult bag-mask ventilation (BMV), difficult ventilation via an extraglottic device, difficult cricothyroidotomy, and deranged physiology (apnea intolerance or refractory shock) that may make rapid sequence intubation (RSI) hazardous. Methods for evaluating airway difficulty, both anatomic and physiologic, and the management of difficult and failed airways are discussed in detail separately. (See "Rapid sequence intubation for adults outside the operating room" and "Approach to the anatomically difficult airway in adults outside the operating room" and "Approach to the failed airway in adults outside the operating room".)
In general, RSI is used in patients for whom successful intubation and successful bag-mask ventilation are anticipated, despite any difficult airway attributes that may be identified. A significant number of emergency department patients in need of endotracheal intubation (ETI) have anatomic characteristics that can increase the procedure's difficulty but do not create such severe obstacles as to render RSI contraindicated. Therefore, the majority of such patients can be managed using RSI.
No discreet threshold exists at which RSI is deemed safe or when it is contraindicated. This is due, in part, to the lack of sensitivity and specificity of commonly used guidelines for difficult airway prediction. The LEMON mnemonic is one aid for remembering important predictors of intubation difficulty and has been prospectively validated. It has high negative predictive value, and if patients meet none of the LEMON criteria, it is unlikely that laryngoscopy and intubation will pose significant challenges (table 2) [3,5]. (See "Approach to the anatomically difficult airway in adults outside the operating room".)
Difficult airway prediction guidelines are based primarily on the anesthesia experience, which often involves elective intubations of cooperative patients, and may not be applicable to the emergency department. Furthermore, patients frequently present to the emergency department in extremis, and clinicians may be unable to obtain a history or to assess the airway adequately to determine whether a difficult intubation is likely [6]. Nevertheless, we suggest emergency clinicians assess any airway they may need to manage, to the extent possible given the constraints of time and patient cooperation, in order to be prepared for a potentially difficult airway.
Few studies have assessed difficult intubation in the emergency department and its true incidence is unknown. In an observational study performed in an academic emergency department, nearly 50 percent of all intubations were predicted to be either challenging or difficult based on a bedside anatomic assessment [4]. Intubators were asked only to consider anatomic limitations and not the time available to complete the procedure or physiologic characteristics that might complicate intubation. Therefore, the rate of predicted difficulty should be considered a minimum number. Difficult airways are likely more common among patients intubated in the emergency department than in the operating room, where patients are generally evaluated preoperatively and airway management can be done electively.
Part of the problem in determining the incidence of airway difficulty stems from the various ways of defining what constitutes a "difficult airway" or "difficult intubation." Determining that an intubation was difficult can only happen after the procedure is completed. How often an airway, predicted to be challenging based on bedside assessment, turns out to be difficult to manage (requires multiple attempts or a rescue maneuver) varies based on the definition of intubation difficulty. Estimates are that the rate of difficult intubation in the emergency department is as high as 30 percent [7]. Fortunately, intubation failure rates are much lower; rescue cricothyroidotomy is performed in less than 0.5 percent of emergency department patients [1,2]. (See "Approach to the anatomically difficult airway in adults outside the operating room".)
THE MAIN AIRWAY ALGORITHM — The algorithms presented in this review were developed as part of a national airway training course and represent an initial approach to advanced emergency airway management (algorithm 1 and algorithm 2) [8]. Once the need for intubation is decided, the clinician must determine the best approach. The following questions represent the major branch points in the main airway algorithm and reflect the important principles underlying advanced airway management:
●Is the patient in arrest or an agonal state? If so, an immediate intubation attempt without medications is appropriate (algorithm 2). (See 'The crash airway algorithm' below.)
●Is the patient sufficiently aware to respond to direct laryngoscopy (ie, gag, thrash, vomit)? If not, and the patient has a true Glasgow Coma Scale (GCS) score of 3, then the patient is unlikely to benefit from sedative and paralytic medications. Direct or video laryngoscopy, without medications, is indicated (algorithm 2). (See 'The crash airway algorithm' below.)
•One important exception to this recommendation is the patient who is unresponsive because of a critical intracranial insult (eg, intracranial hemorrhage). In such patients RSI provides superior control of adverse reflexes that may increase intracranial pressure. (See "Induction agents for rapid sequence intubation in adults outside the operating room", section on 'Head injury or stroke'.)
●If the patient is not in cardiac arrest or an agonal state, is a difficult airway predicted? The goal is to identify anatomic and physiologic characteristics likely to cause circulatory collapse or difficult intubation, ventilation, or oxygenation. In such cases, it is prudent to choose an intubation technique that avoids full induction or paralysis and allows the patient to maintain spontaneous respirations during the procedure (algorithm 3). (See "Approach to the anatomically difficult airway in adults outside the operating room".)
●As long as oxygenation is adequate and no significant anatomic or physiologic difficulty is anticipated, rapid sequence intubation is advised. (See "Rapid sequence intubation for adults outside the operating room".)
●If intubation was attempted but unsuccessful, is oxygenation adequate (ie, pulse oximetry above 90 percent)? If not, and if oxygenation does not immediately improve with better bag-mask ventilation, then a failed airway exists (algorithm 4). In most circumstances, a patient who is unable to be intubated and cannot be oxygenated will require a surgical airway (ie, cricothyroidotomy). (See "Approach to the failed airway in adults outside the operating room".)
●If intubation is unsuccessful despite three attempts by an experienced operator, regardless of the ability to oxygenate, this too constitutes a failed airway. (See "Approach to the failed airway in adults outside the operating room".)
THE CRASH AIRWAY ALGORITHM — The crash approach is predicated on the need for immediate airway control in the unresponsive patient unlikely to benefit from medications. The "crash" patient is unconscious, unresponsive, and has absent or severely compromised cardiopulmonary function. The assumption is that the patient is relaxed and unresponsive, similar to the conditions achieved with RSI. The following questions represent the major branch points in the crash airway algorithm and reflect the important principles underlying crash airway management (algorithm 2) [8]:
●If intubation is attempted but unsuccessful, can oxygenation be maintained adequately with a bag and mask? This often cannot be determined by pulse oximetry, because the patient may not have a pulse oximetry waveform. Instead, the provider must rely on assessment of chest rise, mask seal, and bag compliance to determine the adequacy of bag-mask ventilation.
•If attempts at oxygenation are ineffective then a failed airway exists. (See "Approach to the failed airway in adults outside the operating room".)
•If oxygenation is judged effective after the failed intubation attempt, then a single dose of a muscular relaxing agent is administered before subsequent intubation attempts. In the absence of contraindications, high dose succinylcholine (2 mg/kg) is useful to overcome residual muscular rigidity. This dose is recommended to maximize the speed of onset in patients with severe circulatory compromise. If succinylcholine is felt to be contraindicated, rocuronium at a dose of 1.5 mg/kg can be used.
●If intubation is unsuccessful despite three attempts by an experienced operator then a failed airway exists. (See "Approach to the failed airway in adults outside the operating room".)
SUMMARY AND RECOMMENDATIONS
●We recommend rapid sequence intubation (RSI) for emergency intubations when significant anatomic or physiologic difficulty is not anticipated and a crash airway scenario does not exist. The main airway algorithm provides an overall approach to emergency airway management (algorithm 1). The algorithm is discussed above. (See 'The main airway algorithm' above.)
●The crash airway algorithm provides an approach to airway management in patients who are unconscious, unresponsive, and have absent or severely compromised cardiopulmonary function (algorithm 2). The algorithm is discussed above. (See 'The crash airway algorithm' above.)
●We recommend that clinicians employ an approach to emergency airway management that accounts for the possibility of difficult intubation, difficult bag-mask ventilation, difficult extra-glottic device ventilation, and difficult cricothyroidotomy. Methods for evaluating airway difficulty and management of difficult and failed airways are discussed in detail elsewhere. (See "Approach to the anatomically difficult airway in adults outside the operating room" and "Approach to the failed airway in adults outside the operating room".)
ACKNOWLEDGMENT — The editorial staff at UpToDate acknowledge Aaron E Bair, MD, MSc, FAAEM, FACEP, now deceased, who contributed to an earlier version of this topic review.
