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.
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.