Module 12
The American Society of Anesthesiologists'
Management
of the Difficult Airway Algorithm
and Explanation-Analysis of the Algorithm
The ASA Algorithm on the
Management of the Difficult Airway
THE PATIENT WHOSE LUNGS CANNOT BE
VENTILATED BY MASK AND WHOSE TRACHEA CANNOT BE INTUBATED
In rare cases, it is impossible either to
ventilate the lungs of a patient via mask or to intubate the
trachea. Under these circumstances, unless there is an
alternative ventilation method immediately available, death will
rapidly ensue. The LMA is a major advance in the
management of both difficult intubation and difficult
ventilation scenarios and was incorporated into the original ASA
Difficult Airway Management Algorithm in five different places
as either an airway (ventilation device) or a conduit for a
flexible fiberoptic bronchoscope in 1996.11
In fact, it functions so well as a conduit, the LMA Fastrach
(Intubating LMA) was introduced into clinical practice in 1998.9,13,42
Additional non-invasive options for emergency ventilation
include the esophageal tracheal Combitube
(see Chapter 25),
transtracheal jet ventilation (TTJV)
(see Chapter 26)
and the rigid bronchoscope (see
Chapters 27 and 35). It
should be realized that both the Combitube and the LMA are
supraglottic ventilatory devices and may not allow successful
ventilation when airway obstruction occurs at or below the
glottic opening. The same is true of TTJV. Thus, the rigid
bronchoscope has now been introduced into the Difficult Airway
Management Algorithm as a solution to maintain a patent airway
and allow ventilation past an obstruction at these levels.
Although TTJV is easy to perform and can be life-saving; time
and the appropriate equipment is required to implement this
technique, which precludes its use in many urgent emergency
settings. Furthermore, the technique requires some patency of
the glottis and upper airway. Severe subcutaneous emphysema may
result if the needle or catheter is not entirely inside the
tracheal lumen. Additionally, barotrauma may result from
overanxious jet ventilation in the presence of a closed glottis
or proximal airway obstruction.54
Nonetheless, cricothyroid oxygen insufflation or jetting can
convert a scary situation into a controlled one, where direct,
fiberoptic, or retrograde intubation and other techniques become
more practical.
The risks of an invasive rescue technique
must be weighed against the risks of hypoxic brain injury or
death.50
While most anesthesiologists think they should be able to
perform a cricothyrotomy, less than 50% feel competent to
perform one.28
Failure of anesthesiologists to expeditiously perform a
cricothyrotomy is often regarded as a criticism by plaintiff’s
experts in medico-legal actions. Therefore, when faced with a
failed airway, preparations for a surgical airway must begin
immediately and once the decision is made, it is essential to
use an effective technique (see
Chapters 28 and 29). Invasive
airway access, such as TTJV or cricothyrotomy (catheter or
surgical) are temporary measures to restore oxygenation.
Definitive airway management will follow either by tracheal
intubation1,34
or formal tracheostomy.
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