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ChouAirway
Introduction to the
ChouAirway™
A
breakthrough in oroairway design:
The Adjustable Airway Device™
1. What the ChouAirway is
Structure of the ChouAirway
2. How
the ChouAirway Works
Size selection
Technique for using the ChouAirway
The science behind the device
3. Why
the ChouAirway is Better
Special features / design advantages
What the ChouAirway is Achi Corporation
presents its Adjustable Airway Device™—The ChouAirway.™ Designed by
the WuScope1 team of anesthesiologists, it is built on new
understandings of “difficult airway.”2-11
 In
conjunction with the use of a regular face mask, the ChouAirway is to be
placed orally to facilitate and maintain spontaneous or
assisted breathing in emergency resuscitation situations or under general
anesthesia.
The
ChouAirway is intended to overcome upper airway obstruction resulting
from the presence of a large hypopharyngeal tongue, which is often
associated with difficult face mask ventilation, obstructive sleep apnea,
and difficult intubation.2,
7, 8
Structure of the ChouAirway
 Rigid outer
tube. (Fig. 1) Serves as a conduit for and protects
the flexible inner tube from the biting force of the patient’s teeth.
Flexible inner tube. (Fig. 2) Conforms to the patient’s anatomy,
glides over and bypasses the patient’s tongue, and creates a
patent air passage from the mouth opening to the glottis.
The
rigid outer tube (Fig. 1) and the flexible inner tube (Fig. 2) are made
separately and assembled together for use.
Slidable movement of the flexible inner tube adjusts the
intra-oral length of the ChouAirway (Fig. 3).
There are two
sizes of ChouAirway—Adult and Large-Adult.
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How the ChouAirway works Size selection
Adult
ChouAirway is appropriate for approximately 75% of adult patients. However,
you may need to use a Large-Adult ChouAirway in patients with a
long maxilla, large mandible, or caudally-positioned larynx.
Alternatively, if
you are unable to identify these specific patients beforehand, you may use
the size of laryngoscope blades as a reference. Use Adult
ChouAirway in patients you would normally use a Miller 2 or
Macintosh 3 blade. Similarly, a Large-Adult size corresponds to a
Miller 3 or Macintosh 4 blade.
Technique for using the ChouAirway
Inspect the
ChouAirway to make sure the flexible inner tube is positioned along the same
axis as the rigid outer tube. Adjust the alignment if necessary.
Lubricate (e.g., with water base 20% benzocaine spray) both the rigid
and flexible tubes of the distal section of ChouAirway. Use a tongue
depressor to open the patient’s mouth and insert the ChouAirway
at the midline just like inserting a traditional oral airway.
With the ChouAirway
in place and the patient's head extended, place a regular face mask
over the mouth: 1. If you are able to ventilate the
patient easily or if the patient is breathing spontaneously and shows no
sign of airway obstruction, no adjustment of the intra-oral length of the
flexible inner tube is required (Fig. 4). 2. If you
cannot ventilate the patient, or feel resistance/obstruction in the air
passage, push the flexible inner tube further into the patient’s
mouth incrementally (i.e., push in 1cm mark, then reattempt
ventilation) until the resistance/obstruction is relieved (Fig. 5).
3. When using the Adult ChouAirway, if the patient's airway is
still obstructed after you have pushed the flexible inner tube all the way
in, change to the Large-Adult ChouAirway and repeat all steps.
The science behind the device
A conventional oral airway is of single-piece, fixed length construction
using relatively rigid material which does not conform to the patient's
anatomy. Although multiple sizes are available, typically an oral airway is
not long enough to reach beyond the base of tongue. The nasal airway is more
flexible and longer, and follows the natural anatomy to bypass the tongue.
However, the uncertainty of nasal patency and potential complications of
bleeding greatly limit its usefulness. In contrast, optimal airway length to
reach the glottis to provide a patent air passage can be achieved in the
ChouAirway by adjusting the flexible inner tube. Thus, the ChouAirway
preserves the advantages and eliminates the disadvantages of both oral and
nasal airways. The ChouAirway is specifically
designed to address the issue of a large hypopharyngeal tongue,7
an important cause for difficult mask ventilation. In conjunction with the
WuScope, the ChouAirway aims to resolve the “cannot intubate, cannot
ventilate” clinical situations often associated with patients of obesity,
short ramus, caudal larynx, and obstructive sleep apnea.2-11
[back to top] Why the ChouAirway is better
Special features / design advantages
Minimal
instrumentation to the upper airway anatomy. The shorter length and
tapered end of the rigid outer tube combined with the softness of the
flexible inner tube make the ChouAirway less irritating to the
patient emerging from general anesthesia or in emergency resuscitation
situations. The ChouAirway avoids nasal passage intrusion or periglottic
cuff inflation; potential trauma to the upper airway anatomy is minimized.
Complements and
facilitates face mask ventilation. Practitioners often find it difficult
to maintain face mask ventilation in patients under general anesthesia
because the traditional oral airways are not long enough to reach beyond the
base of tongue. With the ChouAirway bypassing the tongue and creating an
unobstructed air passage from the mouth opening to the glottis,
spontaneous or assisted ventilation with a face mask becomes more
effective and easier to maintain in the surgical patients.
Overcome
difficult ventilation in “caudal larynx.” The ChouAirway flexible inner tube
is considerably longer than other common oral airways, thus capable of
reaching beyond the base of tongue to provide a patent air passage in
patients with a short ramus or caudal larynx2-5 in
whom the large hypopharyngeal tongue often causes difficult
ventilation, difficult intubation, and obstructive sleep apnea.7,
8
Added safety
feature. There are two openings at the distal end of the
ChouAirway unlike traditional oral or nasal airways. If one opening is
blocked by pharyngeal tissue, the opposite opening may still provide an
unobstructed air passage.
Reduced number of
airway sizes. The required number of ChouAirway sizes is reduced because
of its adjustability. By moving the flexible inner tube up or down while
ventilating the patient through a face mask, practitioners can find the
optimal airway length and maximize air passage for the patient quickly
and easily, without taking the airway out of the patient's mouth and trying
another size.
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References
1. Wu TL, Chou HC. A new laryngoscope - the combination intubating device.
Anesthesiology 1994; 81:1085-7
2. Chou HC, Wu TL.
Mandibulohyoid Distance in Difficult Laryngoscopy.
Br J Anaesth 1993; 71:335-9 3. Chou HC, Wu TL.
Thyromental distance - shouldn't we redefine its role in the prediction of
difficult laryngoscopy? (letter). Acta Anaesthesiol Scand 1998; 42:136-7
4. Benumof JL.
Prediction of difficult intubation (letter). Acta Anaesthesiol Scand 1998; 42:1128
5. Chou HC, Wu TL.
Reply. Acta Anaesthesiol
Scand 1998; 42:1128 6. Chou HC, Wu TL.
Rethinking the three axes alignment theory for direct laryngoscopy (letter).
Acta Anaesthesiol Scand 2001; 45:261-2
7. Chou HC, Wu TL. Large hypopharyngeal tongue: a shared anatomic abnormality
for difficult mask ventilation, difficult intubation, and obstructive sleep
apnea? Anesthesiology 2001; 94:936-7
8. Chou HC, Wu TL. Long and narrow pharyngolaryngeal passage in difficult
airway. Anesth Analg 2002; 94:478
9. Chou
HC, Wu TL. A further consideration on Mallampati class and laryngoscopy
grade. Anesth Analg 2002; 95:783
10. Chou HC, Wu TL. A
reconsideration of three axes alignment theory and sniffing position.
Anesthesiology 2002; 97:753
11. Chou HC, Wu TL. Thyromental distance and anterior
larynx: misconception and misnomer? Anesth Analg 2003; 96:1526-7 |
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