This is the current release of the guideline.

Definition

A standard definition of the difficult airway cannot be identified in the available literature. For these guidelines, a difficult airway is defined as the clinical situation in which a conventionally trained anesthesiologist experiences difficulty with face mask ventilation of the upper airway, difficulty with tracheal intubation, or both.

The difficult airway represents a complex interaction between patient factors, the clinical setting, and the skills of the practitioner. Analysis of this interaction requires precise collection and communication of data. The Task Force urges clinicians and investigators to use explicit descriptions of the difficult airway. Descriptions that can be categorized or expressed as numerical values are particularly desirable, as this type of information lends itself to aggregate analysis and cross-study comparisons. Suggested descriptions include (but are not limited to):

1. Difficult face mask ventilation: (a) It is not possible for the anesthesiologist to provide adequate face mask ventilation due to one or more of the following problems: inadequate mask seal, excessive gas leak, or excessive resistance to the ingress or egress of gas. (b) Signs of inadequate face mask ventilation include (but are not limited to) absent or inadequate chest movement, absent or inadequate breath sounds, auscultatory signs of severe obstruction, cyanosis, gastric air entry or dilatation, decreasing or inadequate oxygen saturation (SpO₂), absent or inadequate exhaled carbon dioxide, absent or inadequate spirometric measures of exhaled gas flow, and hemodynamic changes associated with hypoxemia or hypercarbia (e.g., hypertension, tachycardia, arrhythmia).
2. Difficult laryngoscopy: (a) It is not possible to visualize any portion of the vocal cords after multiple attempts at conventional laryngoscopy.
3. Difficult tracheal intubation: (a) Tracheal intubation requires multiple attempts, in the presence or absence of tracheal pathology.
4. Failed intubation: (a) Placement of the endotracheal tube fails after multiple intubation attempts.

Evaluation of the Airway

History

An airway history should be conducted, whenever feasible, prior to the initiation of anesthetic care and airway management in all patients. The intent of the airway history is to detect medical, surgical, and anesthetic factors that may indicate the presence of a difficult airway. Examination of previous anesthetic records, if available in a timely manner, may yield useful information about airway management.

Physical Examination

An airway physical examination should be conducted, whenever feasible, prior to the initiation of anesthetic care and airway management in all patients. The intent of this examination is to detect physical characteristics that may indicate the presence of a difficult airway. Multiple airway features should be assessed (See table below entitled "Components of the Preoperative Airway Physical Examination").

Components of the Preoperative Airway Physical Examination

This table displays some findings of the airway physical examination that may suggest the presence of a difficult intubation. The decision to examine some or all of the airway components shown in this table depends on the clinical context and judgment of the practitioner. The table is not intended as a mandatory or exhaustive list of the components of an airway examination. The order of presentation in this table follows the "line of sight" that occurs during conventional oral laryngoscopy.

Additional Evaluation

Additional evaluation may be indicated in some patients to characterize the likelihood or nature of the anticipated airway difficulty. The findings of the airway history and physical examination may be useful in guiding the selection of specific diagnostic tests and consultation.

Basic Preparation for Difficult Airway Management

At least one portable storage unit that contains specialized equipment for difficult airway management should be readily available. Specialized equipment suggested by the Task Force is listed in Table 2 of the original guideline document. If a difficult airway is known or suspected, the anesthesiologist should:

1. Inform the patient (or responsible person) of the special risks and procedures pertaining to management of the difficult airway.
2. Ascertain that there is at least one additional individual who is immediately available to serve as an assistant in difficult airway management.
3. Administer face mask preoxygenation before initiating management of the difficult airway. The uncooperative or pediatric patient may impede opportunities for preoxygenation.
4. Actively pursue opportunities to deliver supplemental oxygen throughout the process of difficult airway management. Opportunities for supplemental oxygen administration include (but are not limited to) oxygen delivery by nasal cannulae, face mask, laryngeal mask airway (LMA), insufflation, or jet ventilation during intubation attempts; and oxygen delivery by face mask, blow-by, or nasal cannulae after extubation of the trachea.

Strategy for Intubation of the Difficult Airway

The anesthesiologist should have a preformulated strategy for intubation of the difficult airway. The algorithm shown in Figure 1 of the original guideline document is a strategy recommended by the Task Force. This strategy will depend, in part, on the anticipated surgery, the condition of the patient, and the skills and preferences of the anesthesiologist. The strategy for intubation of the difficult airway should include:

1. An assessment of the likelihood and anticipated clinical impact of four basic problems that may occur alone or in combination:
   1. Difficult ventilation
   2. Difficult intubation
   3. Difficulty with patient cooperation or consent
   4. Difficult tracheostomy
2. A consideration of the relative clinical merits and feasibility of three basic management choices:
   1. Awake intubation versus intubation after induction of general anesthesia
   2. Use of noninvasive techniques for the initial approach to intubation versus the use of invasive techniques (i.e., surgical or percutaneous tracheostomy or cricothyrotomy)
   3. Preservation of spontaneous ventilation during intubation attempts versus ablation of spontaneous ventilation during intubation attempts
3. The identification of a primary or preferred approach to:
   1. Awake intubation
   2. The patient who can be adequately ventilated but is difficult to intubate
   3. The life-threatening situation in which the patient cannot be ventilated or intubated
4. The identification of alternative approaches that can be employed if the primary approach fails or is not feasible:
   1. Table below titled "Techniques for Difficult Airway Management" displays options for difficult airway management.
   2. The uncooperative or pediatric patient may restrict the options for difficult airway management, particularly options that involve awake intubation. Airway management in the uncooperative or pediatric patient may require an approach (e.g., intubation attempts after induction of general anesthesia) that might not be regarded as a primary approach in a cooperative patient.
   3. The conduct of surgery using local anesthetic infiltration or regional nerve blockade may provide an alternative to the direct management of the difficult airway, but this approach does not represent a definitive solution to the presence of a difficult airway, nor does it obviate the need for a preformulated strategy for intubation of the difficult airway.
5. The use of exhaled carbon dioxide to confirm tracheal intubation

Techniques for Difficult Airway Management

This table displays commonly cited techniques. It is not a comprehensive list. The order of presentation is alphabetical and does not imply preference for a given technique or sequence of use. Combinations of techniques may be employed. The techniques chosen by the practitioner in a particular case will depend upon specific needs, preferences, skills, and clinical constraints.

Strategy for Extubation of the Difficult Airway

The anesthesiologist should have a preformulated strategy for extubation of the difficult airway. This strategy will depend, in part, on the surgery, the condition of the patient, and the skills and preferences of the anesthesiologist. The preformulated extubation strategy should include

1. A consideration of the relative merits of awake extubation versus extubation before the return of consciousness
2. An evaluation for general clinical factors that may produce an adverse impact on ventilation after the patient has been extubated
3. The formulation of an airway management plan that can be implemented if the patient is not able to maintain adequate ventilation after extubation
4. A consideration of the short-term use of a device that can serve as a guide for expedited reintubation. This type of device is usually inserted through the lumen of the tracheal tube and into the trachea before the tracheal tube is removed. The device may be rigid to facilitate intubation and/or hollow to facilitate ventilation.

Follow-up Care

The anesthesiologist should document the presence and nature of the airway difficulty in the medical record. The intent of this documentation is to guide and facilitate the delivery of future care. Aspects of documentation that may prove helpful include (but are not limited to)

1. A description of the airway difficulties that were encountered. The description should distinguish between difficulties encountered in face mask or LMA ventilation and difficulties encountered in tracheal intubation.
2. A description of the various airway management techniques that were employed. The description should indicate the extent to which each of the techniques served a beneficial or detrimental role in management of the difficult airway.

The anesthesiologist should inform the patient (or responsible person) of the airway difficulty that was encountered. The intent of this communication is to provide the patient (or responsible person) with a role in guiding and facilitating the delivery of future care. The information conveyed may include (but is not limited to) the presence of a difficult airway, the apparent reasons for difficulty, how the intubation was accomplished, and the implications for future care. Notification systems, such as a written report or letter to the patient, a written report in the medical chart, communication with the patient's surgeon or primary caregiver, a notification bracelet or equivalent identification device, or chart flags, may be considered.

The anesthesiologist should evaluate and follow up with the patient for potential complications of difficult airway management. These complications include (but are not limited to) edema, bleeding, tracheal and esophageal perforation, pneumothorax, and aspiration. The patient should be advised of the potential clinical signs and symptoms associated with life-threatening complications of difficult airway management. These signs and symptoms include (but are not limited to) sore throat, pain or swelling of the face and neck, chest pain, subcutaneous emphysema, and difficulty swallowing.

An algorithm is provided in the original guideline document for the strategy for intubation of the difficult airway.

Scientific evidence was derived from multiple sources, including aggregated research literature (with meta-analyses when appropriate), surveys, open presentations, and other consensus-oriented activities. The findings of the literature analyses were supplemented by the opinions of Task Force members and surveys of the opinions of a panel of consultants.

Not applicable: The guideline was not adapted from another source.

2003 May

American Society of Anesthesiologists - Medical Specialty Society

American Society of Anesthesiologists

Task Force on Management of the Difficult Airway

Task Force Members: Robert A. Caplan, MD (Chair), Seattle, Washington; Jonathan L. Benumof, MD, San Diego, California; Frederic A. Berry, MD, Charlottesville, Virginia; Casey D. Blitt, MD, Tucson, Arizona; Robert H. Bode, MD, Boston, Massachusetts; Frederick W. Cheney, MD, Seattle, Washington; Richard T. Connis, PhD, Woodinville, Washington; Orin F. Guidry, MD, Jackson, Mississippi; David G. Nickinovich, PhD, Bellevue, Washington; Andranik Ovassapian, MD, Chicago, Illinois

Not stated

This is the current release of the guideline.

None available

None available

This NGC summary was completed by ECRI on July 13, 2005. The information was verified by the guideline developer on July 20, 2005.

This NGC summary is based on the original guideline, which is subject to the guideline developer's copyright restrictions.