Full text of DOI:10.1016/S1067-991X(01)70058-2

Does the ILMA Make Sense in HEMS?
David Dries, MSE, MD,1,2 Ralph Frascone, MD, Paul Molinari, MD, William Heegaard, MD, Greg Pippert,2,4 MD,
and Robert Reardon, MD
1,2
1
2,3
2,3
1
9
As first reported by Brain by the early 1980s, the laryngeal success rate with this device. One study from the emergency
mask airway (LMA) represented a new approach to airway medicine literature evaluated success with ILMA insertion and
management. The LMA has been used to facilitate tracheal ventilation in a mannequin model. Inexperienced operators
intubation by a variety of methods. In fact, the LMA has were given a brief demonstration of the ILMA and subsequently
been used to intubate the patient with difficult tracheal ac- had a 97% success rate for blind ETT placement.
cess. A recent addition to this technique, the intubating la-
Most studies do not mention the incidence of accidental
ryngeal mask airway (ILMA), shown in Figure 1, first was esophageal intubation during blind ETT placement through the
1
,2
proposed by Brain and coworkers in 1995. The ILMA in- ILMA. Three studies report this complication, and in all cases,
corporates the standard LMA cuff in sizes 3, 4, or 5, along the mistake was recognized quickly and corrected. The inci-
with a metal airway tube and handle. The handle allows dence of esophageal intubation with the ILMA is probably
users to manipulate the device within the patient’s airway. 5%.1
0,11
End-tidal CO detectors or esophageal detector devices
2
The airway tube component has a wider internal diameter should be available when blind intubation is performed with
and is shorter than the standard LMA tube. A silicone rub- the ILMA.
ber bite block surrounds the upper portion of the stem.
A lighted stylet may improve the success rate of blind intu-
In current use, the ILMA introduces an 8.0 mm cuffed endo- bation. A standard lighted stylet or variation of this device may
tracheal tube (ETT). The standard LMA only admits up to a 6.0 allow manipulation of the ILMA handle to ensure that the glow
mm cuffed ETT. In addition, the cuff of such a tube may not re- is directed into the midline at the laryngeal prominence before
liably come to lie in the trachea below the vocal cords because an ETT is advanced into the trachea.12 With the addition of a
of the LMA stem length. To overcome these problems, the lighted stylet, the intubation success rate with the ILMA is
ILMA was modified to function as a primary airway or as a nearly 100%. In one study,13 nurses with no prior airway expe-
means to facilitate placement of a variety of cuffed ETTs. As de- rience successfully intubated 95% of patients using the combi-
veloped, the ILMA’s rigid handle allows the operator to transmit nation of an ILMA and lighted stylet.
position changes directly to the inflatable cuff within the patien-
In emergency medicine practice today, the most important
t’s airway, unlike the standard LMA.3,4 Brain points out that this role for the ILMA appears to be as a part of the difficult airway
flexible alignment of the ILMA with the laryngeal inlet facilitates management protocol, as a backup device for failed direct laryn-
tracheal intubation while allowing the patient’s lungs to venti- goscopy, and for ETT placement. Interestingly, available studies
late throughout the procedure.
suggest the ILMA is just as successful for patients with difficult
Development of the LMA and the ILMA coincides with a airway anatomy as for those with normal airway anatomy.8,14
growing number of reports that highlight the potential for com-
plications when repeated unsuccessful attempts at invasive en-
5
dotracheal intubation take place. In fact, recent guidelines
1
2
3
4
. Regions Hospital/HealthPartners, St. Paul, Minn.
6
from the American Heart Association embrace a less aggressive
approach to invasive airway placement until appropriately
trained personnel and other resources are available.
The success rate of blind intubation through the ILMA
seems to be higher than 90% in large series of patients, even
. Life Link III, St. Paul, Minn.
. Hennepin County Medical Center, Minneapolis, Minn.
. St. Cloud Hospital, St. Cloud, Minn.
Address for correspondence:
7,8
with difficult airways or spine immobilization. Only reduced
oral opening (less than 2 cm) hampers use of the ILMA. The
ILMA more than doubles the blind intubation rate compared
with a standard LMA, and the success rate does not appear to
depend on the operator’s clinical experience. Available litera-
ture on the subject suggests that 10 to 20 ILMA intubations are
necessary to develop sufficient experience with this device. A
steep learning curve appears to be present for the first several
attempts at intubation using the ILMA. However, other reports
suggest that operators with little experience can achieve a high
David J. Dries, MSE, MD, Regions Hospital, Department of
Surgery, North Bldg., 3rd Floor, Suite 2, 640 Jackson St., St. Paul,
MN 55101-2595
Copyright © 2001 by Air Medical Journal Associates
1067-991X/2001/$35.00 + 0
Reprint no. 74/1/118325
doi:10.1067/mmj.2001.118325
September-October 2001
35

Advantages
Short learning curve, blind insertion
Rescue airway in ED
Allows ventilation during placement of definitive tracheal tube
Tracheal intubation can be accomplished
Can be used in confined spaces, when operator astride patient
Effective with difficult airway anatomy
Allows intubation in the neutral position in the event of C-spine
injury
Disadvantages
Dilute experience with ETT use
Costs more than ETT
Requires muscle relaxant use or deep sedation
Aspiration; vomiting in patient without muscle relaxant
Figure 1. Components of the intubating laryngeal mask airway.
An endotracheal tube may be passed through the airway tube.
arena cannot be assumed to have an empty stomach, and intu-
bation will be attempted under poorly controlled circum-
stances. Notably, however, intubation in HEMS traditionally is
performed using RSI. Limited available literature suggests the
This is because characteristics that make direct laryngoscopy use of RSI agents in conjunction with subsequent administra-
difficult—including an anterior larynx, small mandible, and de- tion of muscle relaxants, as is common practice in the air med-
creased neck movement—will not affect ILMA placement.
ical industry, may reduce the incidence of vomiting. Although
Another group of patients who may benefit from the ILMA is the use of muscle relaxants to prevent aspiration is not guaran-
the set with difficult face mask ventilation. Using rapid se- teed, routine use of these agents should prevent forceful vomit-
quence induction (RSI) on patients who are difficult to ventilate ing.21
with a face mask can be problematic. Five percent of adults in
Other complications of the ILMA are unlikely. Sore throat
the general population may be difficult to ventilate with a face and hoarseness after the ILMA have been reported. Whether
mask because of obesity, facial hair, or other anatomic fac- these reports relate to trauma from the tip of an inserted ETT or
15,16
22
tor.
The ILMA allows most of these individuals to be venti- from mucosal pressures created by the ILMA cuff is unclear.
lated because those problems do not affect successful place- Minor laryngeal injuries have been reported after blind intuba-
ment. In fact, the ILMA can ventilate about 99% of all patients tion with the ILMA. Swelling of the epiglottis after blind ILMA
and is more effective than face mask ventilation for less experi- intubation also has been reported; therefore, excessive force
enced providers.
should be avoided. Finally, after intubation is accomplished, the
The ILMA also may be a good choice for patients with cer- ILMA should be removed to avoid pressure injury to the pha-
vical spine injury. Small randomized studies suggest the ILMA ryngeal mucosa.23
is more reliable than the standard LMA or direct laryngoscopy
Does the ILMA have a role in HEMS? We ask that you con-
during in-line stabilization of the cervical spine.17,18 A variety sider these summary points:
of case reports also indicate the ILMA may be effectively used
The ILMA has a brief learning curve regardless of the oper-
during in-line stabilization with awake patients or with RSI.
Interestingly, some authors suggest the ILMA may create pos-
terior pressure on the midportion of the cervical spine. These
authors warn that the ILMA should be used with caution in
patients who are susceptible to injury from cervical flexion.19
Because the ILMA may move the cervical spine in the opposite
direction of the direct laryngoscope, it may be appropriate to
choose an intubation technique based on the perceived type of
cervical injury.
ator’s background. This less-invasive means provides effective
ventilation and should work well in the setting of RSI as per-
formed by HEMS crews. Although the ILMA is designed to fa-
cilitate ETT insertion, effective ventilation should be obtained
with this device alone.
The ILMA can be placed in an aircraft even if the operator
is astride the patient. This device offers a significant advance
over simple bag/valve/mask ventilation for the patient whose
airway becomes difficult in the air and the only alternative to
facilitate invasive endotracheal intubation is landing to allow
an operator to reach the head of the stretcher.
Perhaps the ILMA’s greatest limitation is the risk of aspira-
tion. The anesthesia literature suggests that the risk of aspiration
with the LMA is about 2.6 per 10,000 elective cases and 11 per
20
1
0,000 emergency cases. Clearly, patients seen in the HEMS The LMA appears worthy of consideration in the HEMS en-
36
Air Medical Journal 20:5

vironment. Polk and coworkers24 recently reported in Air
11. Kapila A, Addy EV, Verghese C, Brain AI. The intubating laryngeal mask airway: an
initial assessment of performance [see comments]. Br J Anaesth 1997;79:710-3.
Medical Journal using the LMA in simulation of patients with
difficult extraction. Clearly, work such as this needs to be ex-
panded using the ILMA as well in the preclinical and clinical
arena.
1
2. Dimitriou V, Voyagis GS. Tracheal intubation via the intubating laryngeal mask by
inexperienced personnel [letter; comment]. Br J Anaesth 2000;84:538-9.
3. Dimitriou V, Voyagis GS. Use of an illuminated flexible catheter for light-guided
tracheal intubation through the intubating laryngeal mask by nurses. Eur J Anaes-
thesiol 2000;17:46-9.
1
Finally, should we consider the ILMA as a primary means of 14. Brain AI, Verghese C, Addy EV, Kapila A, Brimacombe J. The intubating laryngeal
mask. II: A preliminary clinical report of a new means of intubating the trachea. Br
airway control rather than a rescue device in the midportion of
our difficult airway algorithm? The importance of airway man-
J Anaesth 1997;79:704-9.
1
5. Reed A. The unanticipated difficult airway. Anesthesiol Clin North Am
agement to successful HEMS practice, as suggested by the vol-
1996;14:443-69.
ume of literature in this journal alone on this subject, warrants 16. Langeron O, Masso E, Huraux C, Guggiari M, Bianchi A, Coriat P, Riou B. Prediction
of difficult mask ventilation. Anesthesiology 2000;92:1229-36.
further systematic attempts to answer this question.
1
1
1
7. Asai T, Murao K, Tsutsumi T, Shingu K. Ease of tracheal intubation through the in-
tubating laryngeal mask during manual in-line head and neck stabilisation.
Anaesthesia 2000;55:82-5.
References
1
2
3
4
5
. Brain AI, Verghese C, Addy EV, Kapila A. The intubating laryngeal mask. I: Develop-
ment of a new device for intubation of the trachea. Br J Anaesth 1997;79:699-703.
. Benumof JL. Laryngeal mask airway and the ASA difficult airway algorithm [see
comments]. Anesthesiology 1996;84:686-99.
8. Asai T, Wagle AU, Stacey M. Placement of the intubating laryngeal mask is easier
than the laryngeal mask during manual in-line neck stabilization. Br J Anaesth
1999;82:712-4.
9. Kihara S, Watanabe S, Brimacombe J, Taguchi N, Yaguchi Y, Yamasaki Y. Segmental
cervical spine movement with the intubating laryngeal mask during manual in-
line stabilization in patients with cervical pathology undergoing cervical spine
surgery. Anesth Analg 2000;91:195-200.
. Rosenblatt WH, Murphy M. The intubating laryngeal mask: use of a new ventilating-
intubating device in the emergency department. Ann Emerg Med 1999;33:234-8.
. Tobias JD. The laryngeal mask airway: a review for the emergency physician. Pediatr
Emerg Care 1996;12:370-3.
2
0. Brimacombe J, Berry A. The incidence of aspiration associated with the laryngeal
. Jaeger K, Ruschulte H, Osthaus A, Scheinichen D, Heine J. Tracheal injury as a se-
quence of multiple attempts of endotracheal intubation in the course of a pre-
clinical cardiopulmonary resuscitation. Resuscitation 1999;43:147-50.
. American Heart Association guidelines 2000 for cardiopulmonary resuscitation and
emergency cardiovascular care. Circulation 2000;102(8 Suppl):1358-70.
. Chan YW, Kong CF, Kong CS, Hwang NC, Ip-Yam PC. The intubating laryngeal mask
airway (ILMA): initial experience in Singapore [see comments]. Br J Anaesth 1998;
mask airway: a meta-analysis of the published literature. J Clin Anesth 1995;7:297-
305.
2
2
2
1. van Vlymen JM, Coloma M, Tongier WK, White PF. Use of the intubating laryngeal
mask airway: are muscle relaxants necessary? Anesthesiology 2000;93:340-5.
2. Brimacombe J, Keller C, Berry A. Pharyngolaryngeal morbidity with the intubating
laryngeal mask airway [letter; comment]. Anaesthesia 1998;53:1231.
6
7
3. Takenaka I, Aoyama K, Nagaoka E, Seto A, Niimima K, Kadoya T. Malposition of the
epiglottis after tracheal intubation via the intubating laryngeal mask. Br J Anaesth
81:610-1.
8
9
1
. Baskett PJ, Parr MJ, Nolan JP. The intubating laryngeal mask. Results of a multicen-
1999;83:962-3.
tre trial with experience of 500 cases. Anaesthesia 1998;53:1174-9.
2
4. Polk DO, Super DM, Kovach B, Russell S, Mancuso C, Fallon W. Comparison of the
laryngeal mask airway versus blind endotracheal intubation in the simulated en-
trapped patient: a preliminary study. Air Med J 2001;20(2):21-2.
. Levitan RM, Ochroch EA, Stuart S, Hollander JE. Use of the intubating laryngeal mask
airway by medical and nonmedical personnel. Am J Emerg Med 2000;18:12-6.
0. Fukutome T, Amaha K, Nakazawa K, Kawamura T, Noguchi H. Tracheal intubation
through the intubating laryngeal mask airway (LMA-Fastrach) in patients with dif-
ficult airways [see comments]. Anaesth Intensive Care 1998;26:387-91.
September-October 2001
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