Page 83 - Journal of Special Operations Medicine - Fall 2014

Methods 75% of the time). There were minimal differences in
success rates based on years of experience (Figure 2).
Local intuitional review board approval was obtained.
Following this, our study was conducted in a medical Figure 1 Percentage of intubation tube exchange success
school anatomy laboratory using four human cadavers. compared with failure for both the adult bougie and the
Each cadaver was first intubated with a Classic LMA pediatric bougie. Both bougie types used a rotational twist
supraglottic device. The device was checked to ensure technique after insertion through an LMA. The technique is
that it was in the proper position before each attempt. described in the Methods section.
There were 32 participants. Their experience levels
ranged from experienced emergency department nurses
and emergency medicine interns to attending emergency
physicians. Emergency department nurses were included
in the study because they had all had experience with
airway management on par or higher than the new
emergency medicine interns.

Before the study, the participants were given a 5-minute
lecture and demonstration of the correct placement of
the LMA. They also were instructed on bougie place- Figure 2 Categorization of the study’s participants into
ment through the LMA, with emphasis on obtaining four groups: greater than 74% success, 50% to 74% success,
a 90- to 180-counterclockwise rotation as the bougie 25% to 49% success, and less than 25% success. For the
made contact with the anterior wall of the hypophar- adult bougie (shown in blue), a relatively large percentage
ynx. It was further demonstrated how to load and pass of participants were in the higher success groups. For the
the ETT over the bougie, although the end point in the pediatric bougie (shown in red), a small percentage of
experiment was successful placement of the bougie itself. participants were in the high success groups. This indicates
the relative amount of participants for each bougie type who
were able to successfully use the rotational twist technique.
The participants were randomly assigned to each of the
four cadavers initially. The participants were blinded as
to which cadaver they would start with and had no prior
intubation experience with any of the cadavers. The re-
searchers were blinded to their cadaver assignments. The
blinding was conducted so that none of the participants
or observers would have any prior knowledge of the
relative difficulty or ease of the upcoming intubation at-
tempt. After the first cadaver, they then switched to the
next numbered cadaver. Each participant made two tube
exchange attempts per cadaver: first using an adult bou-
gie, followed by an attempt using a pediatric bougie. Af-
ter passing the bougie through the LMA, the LMA was
removed and bougie placement was confirmed by either Discussion
an attending or a third-year emergency medicine resident The use of supraglottic devices by both pre-hospital per-
using direct laryngoscopy. The results were recorded as sonnel and physicians is ubiquitous. There are several
either successful or unsuccessful, and this was the pri- articles citing the advantages of SADs in the manage-
mary outcome. Time was not recorded, but each attempt ment of a difficult airway. The use of these devices is
was limited to 20 seconds. Comments were solicited as also widespread as a primary airway modality, espe-
to the perceived level of difficulty for each attempt. cially in prehospital environments or rural hospitals as
a bridge to definitive airway management. There have
5,6
been a handful of studies that examined the preferred
Results
tools and methods for accomplishing a bougie-guided
The overall success rate for tube exchange using the tube exchange through an LMA.
adult bougie was 50.0%. The success rate using the pe-
diatric bougie was 28.1% (Figure 1). Miller et al. identified success rates of bougie passage
through a standard LMA. There was a 52% rate of
2
Although there was only a 50% rate of success, it was tracheal placement in the cadaveric model. A second
noted that some participants were consistently much cadaveric study compared four supraglottic devices for
more successful (31.3% of participants were successful their success rates when passing a bougie. It confirmed

LMA Airway Exchange Using a GEB With Rotational Twist 75