Understanding Anesthesiology - The Global Regional Anesthesia ...

A patient who is deemed to be at risk of aspiration requires
that the airway be “protected” with a cuffed endotracheal
tube regardless of the nature of the surgery.
If the surgery requires a paralyzed patient, then in most
cases the patient is intubated to allow mechanical ventilation.
Figure 5 Laryngeal mask in situ
Mask Airway: Bag mask ventilation may be used to
assist or control ventilation during the initial stages of a
resuscitation or to pre-oxygenate a patient as a prelude
to anesthetic induction and intubation. A mask airway
may be used as the sole airway technique during inhalational
anesthesia (with the patient breathing spontaneously)
but it is only advisable for relatively short procedures
as it “ties up” the anesthesiologist’s hands. It
does not protect against aspiration or laryngospasm
(closure of the cords in response to noxious stimuli at
light planes of anesthesia). Upper airway obstruction
may occur, particularly in obese patients or patients
with very large tongues. In current practice, the use of
a mask as a sole airway technique for anesthesia is
rarely-seen although it may be used for very brief procedures
in the pediatric patient.
Laryngeal Mask Airway (LMA): The LMA is an airway
device that is a hybrid of the mask and the endotracheal
tube. It is inserted blindly into the hypopharynx.
When properly positioned with its cuff inflated, it sits
above the larynx and seals the glottic opening (Figure
5). It is usually used for spontaneously breathing patients
but positive pressure ventilation can be delivered
through an LMA. The LMA does not protect against aspiration.
Like an endotracheal tube, it frees up the anesthesiologist’s
hands and allows surgical access to the
head and neck area without interference. While airway
obstruction due to laryngospasm is still a risk, the LMA
prevents upper airway obstruction from the tongue or
other soft tissues. The LMA also has a role to play in
the failed intubation setting particularly when mask
ventilation is difficult. The #3, #4 and #5 LMA are used
in adults. Many modifications have followed the origi-
Images courtesy of the LMA Group of Companies, 2012. Used with permission.
Images modified by Karen Raymer and Brian Colborne.
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