Full text of DOI:10.1007/BF03016839

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CARDIOTHORACIC ANESTHESIA, RESPIRATION AND AIRWAY
Removal of the connector on the laryngeal mask
airway provides a useful alternative to the intubat-
ing laryngeal mask
[Le retrait du connecteur du masque laryngé permet une utilisation équivalente
au masque laryngé d’intubation]
Carsten Preis MD,* Irene Preis MD†
Purpose: We describe two cases in which fiberoptic intubation
through the standard laryngeal mask airway (LMA) was successful
with large-bore tracheal tubes (TTs) when an intubating LMA
Objectif : Décrire deux cas où l’intubation fibroscopique au travers
du masque laryngé standard (ML) a été réussie avec des tubes tra-
chéaux de grand calibre (TT) alors qu’un masque laryngé d’intubation
(MLI) ne pouvait être utilisé.
(ILMA) could not be used.
o
Clinical features: Patient #1, with obstructive sleep apnea,
underwent elective surgical repair. His mouth opening was just
under 25 mm, but difficult intubation was not anticipated. We
induced general anesthesia, easily ventilated the patient by mask,
and established neuromuscular blockade. Direct laryngoscopy and
attempts to insert either a #5 or a #4 ILMA into the mouth failed.
A standard #4 LMA, with the connector removed, was inserted,
through which a 7.0 mm nasal RAE™ TT, fiberoptically guided,
passed into the trachea at the first attempt.
Éléments cliniques : Le patient n 1, qui présentait une apnée du
sommeil obstructive, devait subir une réparation chirurgicale.
L’ouverture de sa bouche était d’un peu moins de 25 mm, mais on n’a
pas envisagé d’intubation difficile. On a induit l’anesthésie, ventilé
facilement le patient au masque et procédé au blocage neuromuscu-
laire. La laryngoscopie directe et les tentatives pour insérer dans la
bouche, soit le MLI n 5, soit le n 4, ont toutes échoué. On a inséré
un ML n 4 standard, sans connecteur, au travers duquel on a passé
dans la trachée, dès le premier essai, un TT nasal RAETM de 7,0 mm
sous guidage fibroscopique.
o
o
o
Patient #2, with a loosened implant after left hip arthroplasty, under-
went revision prosthesis. Her neck movement was limited. We thus
planned awake securing of the airway, but the patient refused. We
induced anesthesia and established bag-mask-valve ventilation. The
limited neck movement prevented direct laryngoscopy. Visualizing
the laryngeal inlet with the fiberoptic bronchoscope (FOB) proved
impossible as bloody secretions obscured the FOB’s tip. Ventilation
by mask was easy. As an ILMA was not available, we removed a #5
LMA’s connector and passed an 8.0 mm nasal RAE™ TT through
the LMA. Fiberoptic-guided intubation was easy. In both cases, the
remainder of the intraoperative course was uneventful.
o
La patiente n 2 qui présentait un implant mobile, conséquence d’une
arthroplastie de la hanche gauche, a subi une révision prothétique. Les
mouvements de son cou étant limités, on a planifié une intubation vi-
gile, mais la patiente a refusé. On a induit l’anesthésie et amorcé la
ventilation manuelle au masque et au ballon. Les mouvements limités
du cou ont empêché la laryngoscopie directe et la visualisation de l’en-
trée du larynx au moyen du fibroscope bronchique (FOB) s’est révélée
impossible étant donné les sécrétions sanguinolentes qui obstruaient la
pointe du FOB. La ventilation au masque était facile et comme aucun
o
MLI n’était disponible, on a enlevé le connecteur d’un ML n 5 et
inséré un TT nasal RAETM de 8,0 mm au travers du ML. Ainsi, l’intu-
bation sous guidage fibroscopique a été aisée. Dans les deux cas, le
reste de l’intervention s’est bien déroulé.
Conclusion: A standard LMA whose connector has been
removed to allow passage of TTs of >6.0 mm internal diameter
may be substituted for the ILMA when necessary.
Conclusion : Un ML standard dont le connecteur a été enlevé pour
permettre le passage d’un TT de diamètre intérieur >6,0 mm peut
remplacer le MLI s’il le faut.
From the Department of Anesthesiology and Intermediate Care,* Rudolfinerhaus, Vienna, Austria, and the Department of
Anesthesiology,† University of Würzburg, Germany.
Address correspondence to: Dr. Carsten Preis, Department of Anesthesiology and Intermediate Care, Rudolfinerhaus, Billrothstrasse 78,
1
190 Vienna, Austria. Phone: +43-1-36 0 36; Fax: +43-1-36 9 81 10; E-mail: c.preis@rudolfinerhaus.at
Accepted for publication November 21, 2000.
Revision accepted March 8, 2001.

Preis et al.: REMOVAL OF THE CONNECTOR O N THE LMA
601
BURP13 did not improve the laryngoscopic view. As
ventilation by mask was easy and the patient was not at
increased risk of aspiration of gastric contents,1 4 we
decided to perform the tracheal intubation via an
appropriately sized ILMA. However, it proved impossi-
ble to insert either a #5 or a #4 ILMA, because neither
could be passed between the patient’s teeth, despite
twisting manoeuvres. Consequently, a standard #4
LMA was prepared as a conduit for fiberoptic intuba-
tion. After we removed the #4 LMA’s connector, we
preloaded a well-lubricated 7.0 mm nasal RAE™ TT
(Mallinckrodt Medical, Athlone, Ireland) into the LMA1
in the manner described by Benumof for a 6.0 mm TT.
Placing the LMA with the TT inside was very easy
despite the patient’s limited mouth opening.
Subsequent fiberoptic-guided intubation via the #4
LMA was easily performed as described by Benumof.1
The LMA was then removed over the TT, as we have
HEN the laryngeal mask airway
(
LMA, The Laryngeal Mask Company
Ltd., Henley on Thames, Oxon, UK)
was introduced to manage the airway,
W
it proved in addition to be a highly useful aid to
1
fiberoptic intubation with a tracheal tube (TT).
However, its construction imposed length/diameter
limitations on the TTs that could be passed through
it. The intubating laryngeal mask airway (ILMA,
The Laryngeal Mask Company Ltd., Henley on
Thames, Oxon, UK), introduced in 1997, allows easy
passage of a well-lubricated 8.0 mm internal diameter
1,2
(
ID) cuffed TT, and it optimizes the angle at which
3–5
the trachea is intubated. Yet, it has several disadvan-
tages that become apparent with use: because of its
cost, the ILMA may not always be available at every
anesthesia work station; there are concerns about
using the ILMA in patients with limited mouth open-
6
–9
1 5
ing
and in patients wearing semi-rigid neck col-
done previously using microlaryngeal tubes, to enable
surgery to proceed.
1
0
lars. Additionally, the TT designed for use with the
ILMA has a low volume/high pressure cuff and anes-
thesiologists are reluctant to use these TTs for pro-
Case #2
1
1
longed periods. They ought to be replaced as soon
as possible by a high volume/low pressure cuffed TT,
but this manoeuver increases the risk of compromising
the airway, especially in a patient with a difficult air-
way, and should be avoided if there is an alternative.
These disadvantages of the ILMA, which have been
discussed recently in the literature, prompt us to report
how an older technique, using a standard LMA as an
intubation guide for 6 mm ID TTs in patients with dif-
ficult airways, can be adapted for 7 mm ID TTs.
A 61-yr-old woman, height 165 cm, weight 69 kg,
body mass index 25, presented with a loosened
implant after left hip arthroplasty, and was scheduled
for revision prosthesis. During the planning of periop-
erative management, the surgeon indicated that he
anticipated surgery to last a minimum of four hours
and to be attended by excessive blood loss. We thus
decided to secure the patient’s airway with an endo-
tracheal tube (ETT). Because her neck movement was
reduced after atlantoaxial stabilization several years
earlier for atlantoaxial subluxation associated with
rheumatoid arthritis, we anticipated intubation diffi-
culties and planned awake securing of the airway.
However, the patient adamantly refused both region-
al anesthesia and awake fiberoptic intubation.
Following preoxygenation, anesthesia was induced
with a total of 450 mg thiopentone iv, followed by a
total of 0.2 mg fentanyl iv. Bag-mask-valve ventilation
was established and neuromuscular blockade was
induced with 8 mg vecuronium iv. Because of the
patient’s limited neck movement, laryngoscopy with
Macintosh #3 and #4 blades showed only the tip of
the epiglottis. The laryngoscopic view did not
improve even with repositioning of the head and
Case reports
Case #1
A 53-yr-old man, height 170 cm, weight 80 kg, body
mass index 28, presented with obstructive sleep apnea
and subsequently underwent elective uvulopalato-
pharyngoplasty. The patient was classified as ASA
1
2
score II and Mallampati score II. He had normal
teeth and a mouth opening of just under 25 mm, full
neck movement, a normal thyromental distance, and
he denied any history of difficult intubation. His last
previous anesthetic procedure, general anesthesia five
years earlier, had been uneventful.
Following preoxygenation, anesthesia was induced
with propofol 2 mg·kg– iv, midazolam 2 mg iv fol-
1
1 3
BURP. Two attempts to visualize the laryngeal inlet
–1
lowed by infusions of remifentanil 1.5 mg·hr and
propofol 200 mg·hr– iv. Bag-mask-valve ventilation
was established and neuromuscular blockade was
with the fiberoptic bronchoscope (FOB) inserted
nasally proved impossible because bloody secretions in
the oropharynx obscured the FOB’s tip. Ventilation
by mask was easy and the patient was not at increased
1
–1
induced with mivacurium 0.2 mg·kg . Laryngoscopy
with Macintosh #3 and #4 blades showed only the tip
of the epiglottis. Even repositioning of the head and
14
risk of aspiration of gastric contents; thus, we decid-
ed to perform the tracheal intubation via an appropri-

602
CANADIAN JOURNAL OF ANESTHESIA
ately sized laryngeal mask. Because there was no
ILMA available, we used a standard LMA. The #4
LMA did not provide sufficient manual ventilation,
despite proper placement, because of severe air leak-
age. A #5 LMA was easily inserted and functioned
properly. We removed the LMA’s connector, passed
an 8.0 mm nasal RAE™ TT through the LMA, easily
performed fiberoptic-guided intubation, and removed
the LMA over the TT as in Case #1.
withdraw the LMA over these tubes with an extra mar-
gin of safety; at 40 cm they are some 11 cm longer than
the conventional 6 mm ID tube. Having realized the
advantages to be gained from removing the connector,
we wanted to take this a step further. We thus looked
for larger-bore tubes at a length comparable to the 6.0
mm microlaryngeal tubes and found the 7.0 and 8.0
mm nasal RAE™ TTs. At 37 cm, the 7.0 mm nasal
RAE™ tubes are 5.5 cm longer than a conventional TT
of that ID and, at 39 cm, the 8.0 mm nasal RAE™
tubes are 7.5 cm longer. Removal of the mask over the
longer tubes differs in some detail from the methods
In both cases the remainder of the intraoperative
course was uneventful.
1
Discussion
compiled by Benumof and awaits further documenta-
We have shown here that the LMA can be used in
place of the ILMA as a guide to intubation with TTs
of 7.0 and 8.0 mm ID if the connector is first
removed. Removing the connector not only allows
TTs of >6.0 mm to pass through the mask, it also
shortens the LMA’s shaft, so that even standard-
length TTs can be placed midtracheally via the LMA.
To manage the airway in our two patients when the
ILMA failed or was unavailable, we returned to our for-
mer intubation strategy using the standard LMA. First, it
is known that the LMA may be inserted even if the
tion by the authors.
While we originally saw removability of the connector
as a potential risk, we have come to realize and utilize its
benefits. Therefore, we recommend the use of standard
LMAs with the connector removed, in combination with
appropriately sized TTs, in situations in which the ILMA
is disadvantageous or not available. Such standard LMAs
may thus be a welcome supplement to ILMAs when
fiberoptic intubation is contemplated.
Acknowledgement
We thank Jane Neuda for editorial assistance.
1
4
mouth opening is as little as 12 mm, and second, our
observations, reported here, show that it is the connector
that blocks the passage of ETTs >6.0 mm ID through the
LMA’s airway tube, besides adding to its length. In a pre-
vious study we reported that repeated autoclaving impairs
the connector-shaft bond of the LMA such that the con-
nector can be deliberately twisted out of the shaft, but
that the airtightness of the LMA is not thereby dimin-
ished.1 6 We also realized that we could pass larger-bore
TTs through the mask when the connector was removed.
Thus, we began to stock LMAs whose connector could
be removed in our portable storage unit for difficult air-
way management. Whenever a LMA was to be used as a
conduit for fiberoptic intubation, we used one from this
stock and twisted the connector out. After the connector
has been removed, a well-lubricated 7.0 mm TT of what-
ever type passes easily through a #3 or #4 LMA and any
well-lubricated 8.0 mm TT through a #5 LMA. Having
high volume/low pressure cuffs, these TTs do not need
to be replaced in case of prolonged intubation.1 1
Moreover, the sizes of these TTs, which are recommend-
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