Author: Bob Kronemyer
Intubation using video laryngoscopy (VL) with a Macintosh-shaped blade achieved a higher first-pass success (FPS) rate than with conventional direct laryngoscopy (DL) for elective surgeries, an international multicenter, randomized study has concluded.
Results from this trial, which were presented at the 2019 World Airway Management Meeting in Amsterdam (abstract 422), demonstrated an FPS rate of 94% using a Macintosh-shaped blade with the McGrath MAC VL (Medtronic; Figure) versus 82% for DL using a Macintosh blade.
“Over the past few years, most of us had a sense that things simply proceed better with a video laryngoscope: an enhanced view, a much safer feeling, and the ability to follow trainees,” said principal investigator Rüdiger Noppens, MD, PhD, FRCPC, an associate professor of anesthesiology at Western University, in London, Ontario.
Dr. Noppens also noted that several studies have demonstrated VL is very helpful in cases of difficult intubation. “But up until now, there has not been any real evidence to support using a Macintosh video laryngoscope for normal, routine airway management,” he said.
Study Supports Observations
A total of 2,171 patients were divided into two groups: VL (n=1,084) and DL (n=1,087).
Besides a difference in FPS that favored VL, there was a higher percentage of DL procedures with an intubation difficulty scale (Table) scoring higher than 5 (5.6%) compared with VL (1.2%).
Trainees also benefit most from VL for tracheal intubation, according to Dr. Noppens.
|Table. Intubation Difficulty Score for Assessing Airway Factors|
|Mallampati classification||Class I||Class II||Class III-IV|
|Thyromental distance, cm||>6.5||6-6.5||<6|
|Neck movement, degrees||>90||90||<90|
|Interincisor gap, cm||>5||4-5||<4|
|ULBT||Class I||Class II||Class III|
|BMI, body mass index; ULBT, upper lip bite test|
Dr. Noppens said VL has the potential to replace the older DL, which has already occurred in some countries and hospitals. “We know that if you have repeated intubation attempts, the chance of a bad outcome increases for tissue injury, aspiration and hypoxia,” he said.
In addition, the investigators evaluated the impact of using a video laryngoscope for various levels of training. “Younger trainees, in particular, are very efficient in using this device,” Dr. Noppens said. “In fact, these trainees can make up for their lack of experience by using a video laryngoscope instead of DL. By having a camera at the tip of the blade, VL allows you to look around the corner for a better view of the larynx structure of the vocal cord. Younger trainees have excellent eye–hand coordination using VL.”
Also, the attached small screen on the handle of a video laryngoscope permits clinicians nearby to follow the procedure and enable them to give feedback if help is needed.
“Moreover, we have observed a trend toward less injury, particularly soft tissue injury, with VL in our study groups,” Dr. Noppens said.
Based on study results, Dr. Noppens advocates VL using a Macintosh-shaped blade as a first-choice instrument for elective surgery in patients with “normal” airways, especially among younger physicians.
“We also believe VL will soon become standard of care and essentially replace DL,” he said.
Nonetheless, Continued Proficiency Important
Lauren Berkow, MD, a professor of neuroanesthesiology at the University of Florida College of Medicine, in Gainesville, who was not involved in the study, said these results are similar to other studies comparing VL with DL, including the findings of a higher FPS rate for VL and a slightly longer time to intubation.
In the current study, patients with expected difficult intubations, Mallampati class IV, and a high risk for aspiration were excluded, so results are not generalizable to those populations, Dr. Berkow noted.
In addition, because neither intubation technique had a 100% success rate, “results support the importance of having backup plans in case of failure of the primary chosen airway device,” said Dr. Berkow, who is the current president of the Society for Airway Management. “It would be interesting to know the cause of failure in the 6% of failed VL. Was it failure to place the endotracheal tube? This is less of a risk with DL in the setting of a grade 1 view of the cords.”
Furthermore, not all hospitals can afford to have VL available in all ORs for all elective patients, according to Dr. Berkow. “Plus, DL still has a fairly high success rate in elective patients without risk factors for difficulty.”
A downside of using VL routinely on all patients “is that providers may become less proficient in other techniques, such as DL or flexible bronchoscopic intubation,” Dr. Berkow said. “Still, there is no question VL is an important tool.”