Aziz MF, Brambrink AM, Healy DW, et al
Anesthesiology. 2016 Aug 1. [Epub
ahead of print]
Study Summary
A team of investigators retrospectively analyzed 346,861
anesthesia cases that involved attempted tracheal intubation from 2004 to 2013
at seven academic centers. Of these, 1427 patients (0.41%) had a failed direct
laryngoscopy, leading to 1619 subsequent intubation attempts.
The majority of these rescue attempts (69%) were managed
with video laryngoscopy, followed in frequency by flexible fiberoptic (11%),
lighted stylet (8%), supraglottic airway as part of an exchange technique (5%),
or optical stylet (0.6%). More than 1000 anesthesia providers (353 attending
anesthesiologists, 449 residents, and 207 certified registered nurse
anesthetists) managed these rescues after being unable to intubate the trachea
with a traditional laryngoscope.
The study's main take-home message was that video
laryngoscopy had the highest intubation success rate (92%), with the
GlideScope® (Verathon; Bothell, Washington) the most commonly used video
laryngoscope device (89% of the time). The intubation success rate for rescue
was 78% for both the supraglottic airway conduit and flexible bronchoscopic
intubation, followed by 77% for lighted stylet and 67% for optical stylet.
Viewpoint
Inability to intubate the trachea after induction of
general anesthesia is an outcome anesthesiologists aim to avoid. Although there
are patient characteristics that can be used to help predict who will have a
difficult airway, there is no 100% sensitive or specific prediction tool. As a
result, clinicians will encounter unexpectedly difficult airways to intubate,
as this study's 0.41% incidence rate suggests. Any study that sheds light on
the use and success rates of rescue techniques after failed direct laryngoscopy
in adult surgical patients will therefore be priority reading for clinicians.
For the past half-century, the most common method for
intubation was to insert a laryngoscope (which consists of a handle and either
a curved or straight stainless steel blade with a light source) into the
oropharynx, so that the vocal cords are directly visualized. In contrast, the
video laryngoscope has a digital camera on the blade. This means that the
clinician does not directly view the larynx, but rather sees it indirectly on a
screen.
In this study, 89% of rescues used the GlideScope video
laryngoscope, which has a different (ie, 60°) angulation of its blade without
the usual need for anterior displacement of the lower jaw. This helps improve
the view of the larynx, which is projected onto an external liquid crystal
display screen mounted on a separate stand.
The authors found that the use of video laryngoscopy for
rescue of failed direct laryngoscopy increased from 30% in 2004 to more than
80% in 2012. This is not an unexpected result. As video laryngoscopy technology
has become more widely available in surgery suites across the country,
anesthesia providers have been able to gain experience and comfort with the
available devices.
This study's main finding builds on the growing literature
supporting the usefulness of video laryngoscopy in clinical anesthesia care. In
fact, the study showed that more than 90% of the time when intubation was not
possible with the traditional direct laryngoscope, the newer video laryngoscope
proved to be helpful.
The very large sample size of this study (>300,000
cases) is a nice example of the kind of pooled data research made possible by
the Multicenter Perioperative Outcomes Group, a consortium of institutions
formed in 2008 with a shared data set facilitating the investigation of
perioperative outcomes.
It is quite likely that video laryngoscopy devices, with their improved
optics, will increasingly replace traditional direct laryngoscopy in routine
airway management.
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