Ottawa Anesthesia Primer. Patrick Sullivan

all cases where difficulty in airway management will be encountered. With the rapid growth in airway equipment, most clinicians will be unable to acquire expertise with all airway devices. Nevertheless, any clinician involved in airway management must have a clear management plan and appropriate reaction to an airway emergency. Clinicians often have equally valid but different management approaches to the difficult airway. The differences are generally founded in the clinicians past experience and skills acquired with specific airway devices and equipment.

      In the patient undergoing an elective surgical procedure, the anesthesiologist has the luxury of time to permit a full assessment of the airway, to predict difficulties with ventilation and intubation (see Chapter 6), to prepare equipment and medications, and to request assistance from other health care personnel. In an emergency setting, when oxygenation is compromised, only a very limited airway assessment may be possible. Additionally, there may be an inadequate amount of time to prepare equipment and medications properly and to seek assistance from other health care personnel. When difficulty in tracheal intubation is encountered, all efforts should focus on oxygenation not intubation. This is the overwhelming lesson learned from case studies involving the management of a failed airway.

      Chapter 6 includes a discussion regarding the assessment and evaluation of the airway and preparation of equipment prior to intubation. The use of an LMA™ or other laryngeal mask airway device (LMAD) as both a primary airway tool and rescue airway device is discussed in Chapter 8. This following information pertains to the use of specialized airway equipment and devices used for both elective and emergent intubation of the difficult or failed airway. The investment of learning a rational approach to the difficult airway provides the learner with a platform from which to both understand and approach the patient who requires emergent airway management when time is limited.

       The four levels of airway management:

      1 Bag-mask ventilation (BMV)

      2 Placement of an LMA™ or LMAD

      3 Endotracheal intubation

      4 Surgical airway

      Spontaneous or controlled ventilation with the use of a bag and mask or the placement of an LMA™ (or LMAD) may provide acceptable oxygenation and ventilation. When difficulty is encountered with tracheal intubation, it is important that efforts are focused on ensuring adequate oxygenation. In this setting, reverting to bag-mask ventilation or placement of a LMAD may be used as a rescue plan. A specialized LMA™, such as the LMA Fastrach™, may be used a conduit for intubation should this be required.

      Common strategies to improve success with BMV are discussed in Chapter 6, and strategies to overcome difficulties with placement of a LMAD are discussed in Chapter 8. Following are reviews of advanced airway techniques that may be used to achieve tracheal intubation in patients with a difficult airway. When BMV fails and placement of a LMAD or tracheal tube fails, a situation known as a “can’t intubate – can’t ventilate” (CICV) emergency is declared. This is a rare event with an estimated incidence of 0.01 – 0.07% of all intubations, but it is a potentially life-threatening emergency that requires immediate action to avert a disaster. All efforts are focused on optimizing oxygenation of the patient. An emergency call should go out to notify any available health care provider with airway management skills of the emergency and to enlist their assistance. Should attempts at oxygenation fail, an emergency cricothyroidotomy may be required. As soon as the need of an emergency cricothyroidotomy is considered, preferably before a CICV situation arises, the presence of a surgeon skilled in providing an emergency surgical airway should be requested. Early notification may allow time for the surgeon to prepare mentally, examine the patient’s neck, and prepare the necessary equipment. With proper airway evaluation, preparation, and consideration of alternative management strategies, many cases of CICV emergencies can be avoided, but unfortunately not all.

      The American Society of Anesthesiology have published practice guidelines for management of the difficult airway (see Fig. 7.1 and Fig. 7.2).