Airway management

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Nima Nasiri, M.D.[2]

Overview

In cardiopulmonary resuscitation, anaesthesia, emergency medicine, intensive care medicine and first aid, airway management is the process of ensuring that there is an open pathway between a patient’s lungs and the outside world, an the lungs are safe from aspiration. Airway loss is a major cause of preventable prehospital death in trauma patients. Trauma airway management is complicated because of associated pathology and suboptimal intubating conditions, and also because complete preintubation evaluation and planning is rarely possible. Furthermore, trauma patients are at increased risk for hypoxia, airway obstruction, hypoventilation, hypotension, and aspiration.

In nearly all circumstances airway management is the highest priority for clinical care. This is because if there is no airway, there can be no breathing, hence no oxygenation of blood and therefore circulation (and hence all the other vital body processes) will soon cease. Getting oxygen to the lungs is the first step in almost all clinical treatments. The ‘A’ is for ‘airway’ in the ‘ABC’ of cardiopulmonary resuscitation.

Recommendations for evaluation of airway

The basic approach in airway management in emergency setting includes assuring airway patency, protection from aspiration, and providing adequate oxygenation and ventilation. Following are steps that must be considered prior to conducting airway management, these are include:

• History: An airway history should be conducted, whenever it is feasible, before the initiation of anesthetic care and airway management in all patients 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 before intiation of airway management,The intent of this examination is to detect physical characteristics that may indicate the presence of a difficult airway.

• Additional Evaluation. Additional evaluation may be indicated in some patients to characterize the likelihood or nature

of the anticipated airway difficulty. Certain diagnostic tests (e.g., radiography, computed tomography scans, fluoroscopy) can identify a variety of acquired or congenital features in patients with difficult airways

Techniques for airway management prior to hospital arrival

The decision about whether an airway intervention is required is critical to patient care and survival. Depending on the responder's level of training, a quick assessment and decision is made regarding what if any intervention is required. Airway management is of course limited by scope of practice, education of the practitioner, and available resources.

• Spontaneous breathing: Spontaneous breathing remains a viable option for airway management when a provider is confronted with an awake patient possessing a patent airway. Assistance for spontaneous ventilation can be performed through the placement of a nasal or oral airway. Oxygenation can be improved with the supplementation of oxygen via nasal cannula, simple face mask, or nonrebreather face mask. Unfortunately, the maximally achieved FiO2 is often over estimated by care providers and hypoventilation resulting in hypercapnia cannot be normalized with increase oxygen supply.

• Mouth-to-Mouth ventilation: Mouth-to-mouth or mouth-to-nose ventilation is still a recognized management technique for prehospital airway management. However, this modality has fallen out of favor recently with the increasing support of “hands-only” CPR. Proper face masks should be utilized if they are available.

• Bag-mask ventilation: It is a standard initial approach to airway management in the prehospital and hospital settings.
• Proper preoxygenation prior to intubation provides patients with improved oxygenation and increases time to hypoxemia.
• BMV can be applied as a sole practitioner or in conjunction with a second care provider.
• BMV can also occur during spontaneous respirations as a pressure support method for patients with depressed tidal volumes and inadequate ventilation.
• This is similar to the use of CPAP or BiPAP to assist patients who are spontaneously breathing but are not adequately oxygenating or ventilating.

• Oropharyngeal and nasopharyngeal airways:
• This is used as an adjunct device for spontaneous or assisted ventilation.
• Oropharyngeal and nasopharyngeal airways are frequently utilized by prehospital care providers to improve oxygenation and ventilation.
• These devices are frequently used to temporize until a more definitive airway is obtained, and there are several circumstances that prohibit their placement (severe head or facial injuries).

• Supraglottic airway devices: Supraglottic airway (SGA) device placement is very useful to keep the airways open, it has advantages in comparison with Endotracheal tube intubation, or other methods these are include:
  • Requires less training than ETI.
  • It is less invasive than ETI.
  • For care providers not sufficiently trained in ETI these devices can offer better ventilation during transport than BMV alone.
  • SGAs can be used as a backup tool for failed intubation in accordance with the difficult airway algorithm by the American Society of Anesthesiology (ASA).

• Endotracheal intubation: It is the gold standard for definitive airway management in the prehospital setting. ETI advantages are include:
  • It allows for positive pressure ventilation, positive end-expiratory pressure (PEEP), positive pressure recruitment maneuvers, and protection from aspiration.

• Rapid sequence intubation versus no-medication intubation

Pharmacologic muscle paralysis relaxes the pharyngeal and facial musculature and results in improved intubation conditions. Rapid sequence intubation (RSI) techniques incorporate pharmacologic muscle relaxation and are utilized by anesthesiologists and emergency medicine physicians. However, one drawback to these techniques is the elimination of a patient's ability to breathe spontaneously if the intubation fails. Yet many providers conversely argue that optimal intubating conditions should be achieved prior to attempted intubation in the prehospital setting. The reason for this is that prehospital airway intervention is frequently time sensitive due to trauma, cardiac arrest, hypoxemia, or aspiration risk.

Manual Methods

Head Tilt/ Chin Lift

The simplest way of ensuring an open airway in an unconscious patient is to use a head tilt chin lift technique, thereby lifting the tongue from the back of the throat. This is taught on most first aid courses as the standard way of clearing an airway.

Jaw Thrust

• The jaw thrust is a technique used on patients with a suspected spinal injury and is used on a supine patient.
• The practitioner uses their thumbs to physically push the posterior (back) aspects of the mandible upwards - only possible on a patient with a GCS < 8 (although patients with a GCS higher than this should also be maintaining their own patent airway).
• When the mandible is displaced forward, it pulls the tongue forward and prevents it from occluding (blocking) the entrance to the trachea, helping to ensure a patent (secure) airway.

ILCOR no longer advocates use of the jaw thrust by lay rescuers, even for spinal injured victims, although health care professionals still maintain the technique for specific applications. Instead, lay rescuers are advised to use the same head-tilt for all victims.

Removal of Vomit and Regurgitation

• In the case of a patient who vomits or has other secretions in the airway, these techniques will not be enough.
• Suitably trained clinicians may elect to use suction to clean out the airway, although this may not always be possible.
• An unconscious patient who is regurgitating stomach contents should be turned into the recovery position when there is no suction equipment available, as this allows (to a certain extent) the drainage of fluids out of the mouth instead of down the trachea.

Adjuncts to Airway Management

There are a variety of artificial airways which can be used to keep a pathway between the lungs and mouth/nose. The most commonly used in long term or critical care situations is the endotracheal tube, a plastic tube which is inserted through the mouth and into the trachea, often with a cuff which is inflated to seal off the trachea and prevent any vomit being aspirated into the lungs. In some cases, a laryngeal mask airway (LMA) is a suitable alternative to an endotracheal tube, and has the advantage of requiring a lower level of training that an ET tube.

In the case of a choking patient, laryngoscopy or even bronchoscopy may be performed in order to visualize and remove the blockage.

An oropharyngeal airway or nasopharyngeal airway can be used to prevent the tongue from blocking the airway. When these airways are inserted properly, the rescuer does not need to manually open the airway with a head tilt/chin lift or jaw-thrust maneuver. Aspiration of blood, vomitus, and other fluids can still occur with these two adjuncts.

Related Chapters

• Intubation
• Endotracheal Tube
• Laryngeal Mask Airway
• Oropharyngeal Airway
• Nasopharyngeal Airway
• Ventilation
• Cricothyrotomy
• Tracheotomy

References

Emergency Medical Responder (Second Canadian Version). Brady. 2006. pp. 92–97. ISBN 0-13-127824-X.