Page 96 - JSOM Summer 2018

success rate of 87.8% with inexperienced airway providers. 44%; however, it was 100% when using a frontal jaw-thrust
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The US Armed Forces more frequently used the LT for airway insertion technique. In this study, we used the manufacturer’s
interventions. The LTS-D was chosen instead of the LT be- insertion technique. To optimize the chance of a successful
1
cause the patients presenting in a combat environment are most insertion, we should perhaps look to the frontal jaw thrust
often nonfasting and the LTS-D ability to pass a gastric tube to insertion technique of Schalk et al. 32
relieve the gastric pressure would reduce the risk of aspiration.
After performing this study, we observed that the LTS-D did The LT was first developed in 1998 in Europe and spread to
not follow in its predecessor’s track regarding ease of handling the United States, where it received US Food and Drug Admin-
and rate of success. This could depend on various factors. istration approval in 2003 as the King LT (North American
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Rescue, https://www.narescue.com). The manufacturer further
Experience developed it and created the LTS II and the LTS-D, in which
To our knowledge, no study has been reported on clinical first- the feature of accommodating a gastric tube was added. Some
time attempts by inexperienced airway providers using the features of the LTS-D are not applicable for the ordinary LT.
LTS-D. Numerous clinical studies have been done on airway Thus, results of studies with one device are not directly com-
management with the LTS-D. 22,26–29 They all have in common parable with studies using the other device. Compared with
that the people doing the airway intervention have a higher the LT, the ventilation lumen of the LTS-D has been enlarged
degree of airway experience. They possibly do not reflect the and the size of the tip of the device has been reduced. The
military medics’ possible level of skill or the conditions they distal cuff is oval, to better adjust to the esophageal inlet, and
work in. They are an inferior comparator for evidence of air- there is a funnel to facilitate the insertion of a gastric tube. The
way intervention done by inexperienced military medics and LTS-D is longer and has small orifices to optimize ventilation.
combat life savers. When looking at the construction of the LTS-D compared with
the LT, it has a hard plate where the junction of the two coaxial
The numbers presented for first attempt on the second (seven tubes is located. Kikuchi et al. reported this as cause for the
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of eight) and third (three or three) patient supports achieve- tracheal misplacement in 10% of their insertions: “. . . when
ment of a higher success rate for the LTS-D with relatively the LTSII . . . distal end of the drainage tube hit the posterior
little clinical experience. When taking into account the expe- wall of the pharynx, the LTSII bent ventrally at the junction of
rience gained during this study, the accumulated success rate the two coaxial tubes. . . . As the LTSII was advanced further,
with the LTS-D was 14 of 19 (73.7%) for all first attempts this ventral bending was maintained so that the tip moved to-
and 16 of 19 (84.2%) for second attempts. These numbers ward the tracheal inlet. The slimmer and more pointed distal
are not far from those of some previous studies performed by end of the LTSII, compared with the original LT or LTS, makes
anesthesiologists, nurse anesthetists, and paramedics 22,26–29 in the LTSII more prone to bending when pushed against the pos-
which the success rate for the first attempt ranged from 71% terior pharyngeal wall.” We believe that the construction of
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to 88% and from 94.6% to 98% for second attempt. This the LTS-D has made it more rigid and less flexible and that
seems to give support that, if clinical experience is granted, the this can complicate the insertion, causing an enhanced risk for
LTS-D can be used with a significant success rate of insertion trauma to the airway, and increase the risk for complications.
by others than professional airway providers. How long time
this success rate can be maintained after the clinical experience In our protocol for airway interventions, cuff pressure and
and training is for additional studies to examine. cuff volume were recorded during the interventions. Accord-
ing to the manufacturer’s representative, the amount of air to
According to interviews and observations done in our study, inflate in the cuff is shown with different colors of the tube
seven medics felt it difficult to pass the tube past the orophar- connector. The color on the tube connector is marked on the
ynx. Four (50%) medics had a problem inserting the tube included cuff syringe. It must be noted that the volume marked
for the first time, thus giving a relatively low success rate on on the syringe with color grading is correct when using the or-
first-attempt inserts. dinary LT but inaccurate when using the LTS-D, which needs
less volume of air. The medics in this study inflated the cuff
Several reports of complications with new airway adjuncts according to the color of the tube connector, as taught by the
have been published. A study by Dahaba et al. concluded manufacturer’s representative. This caused too much air to be
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that the LTS-D produces a greater and more sustained hemody- inflated in the cuff in 14 cases and rendered a mean cuff pres-
namic and catecholamine stress response than does the LMA. sure of 103.6mmHg, which can affect the mucosal perfusion
Cook et al. and Gaitini et al. reported blood on the tube pressure and decrease the perfusion in this area. This would
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in 12% to 13% of the patients. Kikuchi et al. found that in have gone unnoticed, for example, in the field environment
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10% of the LTS-D insertions, the tip had passed into the tra- where the medics are less likely to have a cuff pressure gauge.
chea. The complications reported in this study and others 18,26,29 Users of the LTS-D should work out guidelines to decrease the
suggest that use of the LTS-D is associated with complications, risk of a cuff pressure higher than 60cmH O. This could be
2
including minor airway trauma. Even if the success rate can be done by education and not relying only on the manufacturer’s
increased by clinical experience, the risk of complications is not color-coding system.
entirely eliminated.
In this study, we compared the LTS-D with the LMA. There
Insertion Technique and LTS-D Construction was a 100% first-attempt success rate with the LMA Ambu
Poor insertion technique and the construction of the LTS-D AuraOnce, which shows that the LMA is an optimal airway
can be causes of complications and the low first-attempt suc- adjunct for use by inexperienced personnel. There are LMAs
cess rate. Schalk et al. studied the insertion technique rec- on the market with the ability to pass a gastric tube, which
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ommended by the manufacturer and concluded that with the could increase the ability to protect the airway from aspira-
standard insertion technique, the success rate was as low as tion. It is the authors’ belief that although the LMA has a high

94 | JSOM Volume 18, Edition 2/Summer 2018