Overview of advanced airway management in adults for emergency medicine and critical care

INTRODUCTION — This topic discusses an algorithmic approach to advanced emergency airway management in adults.

Other issues related to airway management, including basic airway management, difficult airway assessment, rapid sequence intubation, and preventing infection transmission during airway management are discussed in detail elsewhere.

●(See "Basic airway management in adults".)

●(See "Approach to the difficult airway in adults for emergency medicine and critical care".)

●(See "Rapid sequence intubation in adults for emergency medicine and critical care".)

●(See "Overview of infection control during anesthetic care", section on 'Preventing infection transmission to providers'.)

RAPID SEQUENCE INTUBATION

Most common approach in the emergency department — 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 the emergency department (ED), rapid sequence intubation (RSI) is the most frequently used and successful means of intubating the trachea [1,2]. Academic EDs report that it is employed in approximately 85 percent of all patients requiring intubation. Patients who arrive in or develop cardiac arrest and those with predicted highly difficult airways who are intubated using topical anesthesia and sedation, but without neuromuscular blockade as part of a planned “awake” technique comprise the bulk of the remaining patients.

The majority of ED patients in need of endotracheal intubation (ie, excludes the cardiac arrest airway) can be managed using RSI, even if difficult airway attributes are identified. In general, RSI is used in patients for whom successful intubation and successful bag-mask ventilation (BMV) are anticipated. A significant number of ED patients have anatomic characteristics that can increase the procedure's difficulty but do not create such severe obstacles as to render RSI contraindicated, especially when video laryngoscopy is routinely used. (See 'Choice of laryngoscopy technique' below.)

Anticipating the difficult airway — Even though RSI is generally the preferred approach in the ED, a careful assessment for the type and degree of airway difficulty must precede the decision, especially for patients with some anatomic difficulty [3,4]. RSI may be poorly suited for some patients with profound anatomic and physiologic difficult airway attributes, especially those with limited oral access, airway obstruction, or intolerance to brief periods of apnea.

Clinicians should employ an approach to emergency airway management that accounts for the likelihood of difficult intubation, difficult BMV, difficult ventilation via an extraglottic device, difficult cricothyroidotomy, and deranged physiology (apnea intolerance or refractory shock) that may make RSI more 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 in adults for emergency medicine and critical care" and "Approach to the difficult airway in adults for emergency medicine and critical care" and "Approach to the failed airway in adults for emergency medicine and critical care".)

No clear objective 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 our recommended 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 highly unlikely that laryngoscopy and intubation will pose significant challenges (table 1) [3,5]. The ROMAN mnemonic is an equally important aid that helps to identify predictors of challenging BMV [6]. When patients are thought to be exceptionally challenging to intubate or reoxygenate with a bag and mask device, then an awake technique may be preferable to performing RSI (table 2). (See "Approach to the difficult airway in adults for emergency medicine and critical care".)

We recommend emergency clinicians assess patients requiring active airway management to the extent possible given the constraints of time and patient cooperation in order to be prepared for a potentially difficult airway. Difficult airway prediction guidelines are based primarily on elective anesthesia experience, which often involves elective intubations of cooperative patients and may not be applicable to the ED. Difficult airways are likely more common among patients intubated in the ED than in the operating room, where patient selection often occurs during pre-anesthetic evaluation. Patients frequently present to the ED in extremis, and clinicians may be unable to obtain a history or to assess the airway adequately to determine the predicted degree of intubation difficulty [7]. Estimates are that the rate of difficult intubation in the ED is as high as 30 percent [8]. Fortunately, intubation failure rates are much lower; rescue cricothyroidotomy is performed in approximately 0.3 to 0.5 percent of ED patients [1,2]. The incidence of difficult intubation in the ED is discussed further separately. (See "Approach to the difficult airway in adults for emergency medicine and critical care", section on 'Incidence of difficult intubation and first-attempt success'.)

Choice of laryngoscopy technique — In a patient for whom laryngoscopy is planned for emergency intubation, we suggest using a video laryngoscope (VL), if available, instead of direct laryngoscopy (DL). VLs are rigid devices that allow glottic visualization without a direct line of sight, and are increasingly being used for RSI in the ED. Data from 2016 and 2017 from the multicenter National Emergency Airway Registry (NEAR) project showed that VL was used as the first device in nearly two-thirds of all ED intubations in the participating centers [2]. Multivariable regression analysis of more than 11,000 adult intubations in the NEAR data, controlling for confounders of first-attempt success, found that intubators were two to three times more likely to achieve first-attempt success using a VL compared with "optimized" DL (eg, use of tube introducer, external laryngeal manipulation, ramping position). (See "Video laryngoscopes and optical stylets for airway management for anesthesia in adults" and "Direct laryngoscopy and endotracheal intubation in adults" and "Devices for difficult airway management in adults for emergency medicine and critical care", section on 'Evidence about video laryngoscopes in emergency settings'.)

In a 2022 meta-analysis of 222 trials, VL reduced the rate of failed intubation (16,228 patients, 2.5 versus 5 percent, relative risk [RR] 0.44, 95% CI 0.35-0.56), increased first-pass attempt success (19,797 patients, 89 versus 83 percent, RR 1.05, 95% CI 1.03-1.07), reduced the rate of peri-intubation hypoxic events (5434 patients, 3.8 versus 6.6 percent, RR 0.61, 95% CI 0.44-0.85), and improved glottic view as compared with DL [9]. Most trials were in the elective surgery setting, while only seven trials were performed in the ED. Use of Macintosh-style, hyperangulated, and channelled VLs all demonstrated benefit. VL compared with DL also reduced the rate of failed intubation in subgroup analyses of patients without predicted or known difficult airways (10,899 patients, 1.9 versus 3.2 percent, RR 0.54, 95% CI 0.38-0.78) and patients not in the operating room setting (eg, prehospital, ED, intensive care unit [ICU]) (1846 patients, 6.5 versus 9.7 percent, RR 0.68, 95% CI 0.42-1.09), but the latter was not statistically significant.

In a pragmatic, United States multicenter trial, 1417 critically ill adult patients undergoing tracheal intubation in the ED or ICU were randomized to VL or DL for the first attempt (70 percent intubated in ED, 92 percent were performed by an emergency medicine resident or a critical care fellow) [10]. The trial was stopped at the interim analysis for meeting prespecified efficacy criteria. Successful first-attempt intubation was more common using VL compared with DL (85.1 versus 70.8 percent, absolute difference 14.3 percentage points, 95% CI 9.9-18.7 percent). There was no difference in the total number of severe complications (eg, hypoxia, hypotension, vasopressor use, cardiac arrest or death), esophageal intubation, teeth injury, or aspiration, but a first-pass attempt without severe complications was more likely using VL compared with DL (68.7 versus 59 percent, absolute difference 9.7 percentage points, 95% CI 4.5-14.8 percent). Extensive previous intubation experience (eg, at least 100 intubations) was associated with diminished benefit from VL in first-pass success, and DL was actually favored if having performed >250 prior intubations with <25 percent of those using VL.

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) [11]. Once the need for intubation is determined, 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 cardiac arrest or a near-pulseless agonal state for whom chest compressions are either in progress or about to begin? If so, immediately attempt to maintain gas exchange first with a bag-mask device followed by an extraglottic device (EGD) if the resuscitation is prolonged. Definitive airway placement can occur if return of spontaneous circulation (ROSC) is achieved (algorithm 3). (See 'The cardiac arrest airway algorithm' below.)

●For the patient not in cardiac arrest or an agonal state, is a difficult airway predicted? The goal is to identify anatomic and physiologic characteristics that place the patient at high risk of circulatory collapse, failed intubation, or inability to oxygenate should intubation be unsuccessful. In such cases, it is prudent to choose a technique that avoids full induction or paralysis and allows the patient to maintain spontaneous respirations during the intubation (algorithm 4). (See "Approach to the difficult airway in adults for emergency medicine and critical care".)

●As long as oxygenation is adequate and any identified anatomic or physiologic difficulty is not anticipated to prevent successful intubation and oxygenation, rapid sequence intubation (RSI) is advised. (See "Rapid sequence intubation in adults for emergency medicine and critical care".)

●If intubation was attempted but unsuccessful, is oxygenation adequate (ie, pulse oximetry at or above 93 percent)? If not, and if oxygenation does not stabilize or improve with high-quality bag-mask ventilation (BMV) or use of an EGD, then a failed airway exists (algorithm 5). 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 for emergency medicine and critical care".)

●If intubation is unsuccessful despite two attempts by an experienced operator, regardless of the ability to oxygenate, then this also constitutes a failed airway (although a cricothyroidotomy is typically not required if the patient can be oxygenated because there is sufficient time to secure the airway by other means). (See "Approach to the failed airway in adults for emergency medicine and critical care".)

THE CARDIAC ARREST AIRWAY ALGORITHM — The cardiac arrest airway algorithm is used for a patient in cardiac arrest, who has agonal or no respirations with absent or near absent circulation, or when chest compressions have begun (algorithm 3). This is distinct from a patient who is critically ill or injured with unstable vital signs, but has measurable cardiopulmonary function, in which case the clinician should attempt to optimize physiology (eg, administer isotonic intravenous fluid, transfuse blood, or start a vasopressor agent) prior to rapid sequence intubation (RSI). Following a brief period of resuscitation and optimization, the difficult airway algorithm is used to further determine if RSI or an awake technique is needed (algorithm 4) [11]. The following steps summarize the cardiac arrest airway algorithm:

●Initially attempt ventilation and oxygenation by bag-mask ventilation (BMV) or by placement of an extraglottic device (EGD). Assess for effective ventilation clinically by observing chest rise, mask seal, and bag compliance while squeezing.

●If ventilation is unsuccessful without a definitive airway, establish a definitive airway (tracheal intubation or cricothyroidotomy) during the resuscitation, which will likely be accomplished by orotracheal intubation, depending on the circumstances.

If ventilation is successful without a definitive airway:

•But a definitive airway is needed for a procedure (such as a transesophageal echocardiogram) or because of aspiration risk from blood or vomitus in the upper airway, then establish a definitive airway during the resuscitation.

•And a definitive airway is not needed, then continue ventilation with BMV or an EGD. If return of spontaneous circulation (ROSC) is achieved and maintained, then intubate the patient using the difficult airway algorithm.

SUMMARY AND RECOMMENDATIONS

●Rapid sequence intubation (RSI) – The majority of emergency department (ED) patients in need of endotracheal intubation (ie, excludes the cardiac arrest airway) can be managed using RSI, even if difficult airway attributes are identified. In general, RSI is used in patients for whom successful intubation and successful oxygenation (usually via bag-mask ventilation [BMV]) are anticipated. (See 'Rapid sequence intubation' above.)

●Anticipate and prepare for the difficulty airway – Clinicians should employ an approach to emergency airway management that accounts for the possibility of difficult intubation, difficult BMV, difficult extra-glottic device (EGD) ventilation, and difficult cricothyroidotomy. The LEMON (table 1) and ROMAN (table 2) mnemonics are aids for remembering important predictors of difficult intubation and BMV. If the patient has significant hazards based on these bedside assessments, then an awake intubation may be preferable. (See 'Anticipating the difficult airway' above.)

Methods for evaluating airway difficulty and management of difficult and failed airways are discussed in detail elsewhere. (See "Approach to the difficult airway in adults for emergency medicine and critical care" and "Approach to the failed airway in adults for emergency medicine and critical care".)

●Choice of laryngoscopy techniques – In a patient for whom laryngoscopy is planned for emergency intubation, we suggest using a video laryngoscope (VL), if available, instead of direct laryngoscopy (DL) (Grade 2B). As compared with DL, VL reduces the rate of failed intubation, increases first-pass attempt success, improves the glottic view, and reduces peri-intubation hypoxia. This benefit appears consistent for Macintosh-style, hyperangulated, and channelled VLs. (See 'Choice of laryngoscopy technique' above.)

●Main airway algorithm – The main airway algorithm provides an overall approach to emergency airway management (algorithm 1 and algorithm 2). (See 'The main airway algorithm' above.)

●Cardiac arrest airway algorithm – The cardiac arrest airway algorithm provides an approach to airway management in a patient in cardiac arrest, who has agonal or absent respirations with absent or near absent circulation, or when chest compressions have begun (algorithm 3). Ventilation and oxygenation without a definitive airway are first attempted with either BMV or an EGD, and a definitive airway is obtained if these are unsuccessful, or the patient has return of spontaneous circulation (ROSC). (See 'The cardiac arrest airway algorithm' above.)

ACKNOWLEDGMENT — The editorial staff at UpToDate acknowledge Aaron E Bair, MD, MSc, FAAEM, FACEP, now deceased, who contributed to earlier versions of this topic review.