The pediatric GlideScope Video Laryngoscope (GVL), by Verathon is just as useful for managing difficult intubations in children, as it is in adults. Intubating an infant or young child with a GlideScope requires weight/age specific blades and modified technique because the anatomy of infants and toddlers differs from adults.
What’s Different About Infant Anatomy?
Infants and toddlers are not small adults. The pediatric airway often appears more anterior during intubation than the adult airway. The larynx is located much higher in the neck, opposite C2,3 rather than C5,6 as in the average adult. This effectively places the larynx right behind the base of the tongue. The tongue itself is large compared to the size of the mouth, making it more difficult to displace forward. As the child grows older, the anatomy changes, becoming more like a small adult by the age of about 8 years.
Straight blades are usually preferred in our youngest patients because they lift the epiglottis directly. A curved MAC blade depends on pressure on the hyoepiglottic ligament to indirectly lift the epiglottis. In an infant or toddler, because the larynx is so much higher in the neck and right behind the tongue, pressure on the hypoepiglottic ligament often folds the epiglottis down. A MAC blade can hide the glottis from view. Differences in the infant airway combine to make the airway appear more anterior during intubation.
For more information on direct laryngoscopy in small children, or on how the MAC blade manipulates the hyoepiglottic ligament please see the links listed here:
Shape Of The Pediatric GlideScope Blade Varies With Size
The anatomy of a child is constantly morphing. The airway of an infant is different from that of a toddler, which is different from that of an older child and an adult. It stands to reason that a GlideScope blade would have to be shaped specifically for the anatomy in order to work optimally. Indeed, pediatric GlideScope blades for infants and toddlers have different shapes to accommodate the higher position of the larynx.
Not only is the #1 pediatric GlideScope blade shorter. It also has more of a right angle to accommodate the higher larynx.
Note the difference between a Size #1 GlideScope blade on top, and the #2 below it. The shape difference takes into account the fact that the infant larynx is higher in the neck.
What Size Pediatric GlideScope Blade Should I Use In Children?
Four sizes of pediatric GlideScope blade are currently available. Pediatric GlideScope blades (GVL) are usually chosen by patient weight:
- GVL 0 for < 1.5 kg
- GVL 1 for 1.5–3.6 kg
- GVL 2 for 1.8–10 kg
- GVL 2.5: 10-28 kg
However, selecting the next size smaller than recommended for that weight child may provide a better view by allowing more ability to manipulate the angle and depth of the blade in the small pediatric mouth (1,2). You should optimally have both sizes available and be ready to switch blades if the first one doesn’t give a good view.
Inserting The GlideScope
The GlideScope blade is shaped like a longer, more curved Macintosh blade, however, insertion technique is quite different. The MAC blade is inserted to the right side of the mouth and used to slide the tongue to the left. Unlike the MAC, the GlideScope blade is inserted midline and rotated around the tongue in order to line up the camera lens with the larynx.
A More Neutral Head Position Is Helpful
Decreasing the angle the endotracheal tube (ETT) must travel can help. Unlike with the MAC or Miller, this typically means placing the head and neck in a more neutral position rather than an extreme sniffing position.
Because of the pronounced occiput of an infant, you many need to place a small roll under the shoulders to obtain a neutral position. For a toddler, having the head resting on the bed surface, or with a very small folded towel is often optimal.
Shape The Stylet In Your ETT To Match The Blade
You must use a properly curved stylet because the path to the larynx is curved and out of your direct line of sight. Unlike the “hockey-stick” shape used during direct laryngoscopy, the stylet should match the curve on the GlideScope blade. If using a standard stylet, place the stylet into the ETT and then mold it against the GlideScope to match curves. Leave the ETT in the sleeve to keep it sterile.
For children older than about 4 years, it’s often better to use a stiffer, wire stylet rather than the highly flexible slip guide type because the latter is often not long enough, nor stiff enough to guide an ETT larger than size 5.
Because a standard disposable stylet is so malleable, it will occasionally straighten during insertion, especially if the space it tight. This leads to the frustrating situation of being able to see the larynx and not being able to “get there”. A stiffer GlideScope specific, non-disposable stylet is available that is preconfigured to the correct curve. It has a blunt tip to minimize potential for trauma. However, it is much stiffer and can potentially damage pharyngeal structures if you are not gentle. Pull it back slightly before fully inserting the ETT into the trachea. There is both a pediatric and adult dedicated GlideScope stylet. Use of the adult stylet is limited to tubes size 6 or larger.
Pediatric endotracheal tubes are shorter than adult tubes. Always verify that the tip of your stylet is completely inside the endotracheal tube. A stylet extending beyond the tip can damage the mucosa.
Key Points for GlideScope Use
To see a more extensive overall discussion on general technique for intubating with the GlideScope in both adults and children, check out these two articles, as well as the video illustration on GlideScope use from my books :
To summarize some of those principals here:
- Selecting the next size smaller pediatric GlideScope blade than recommended for that weight child may provide a better view by allowing more ability to manipulate the angle and depth of the blade
- A more neutral head position is better.
- Shape the ETT style to match the curve of the blade.
- Look at the patient and periodically glance at the monitor during initial insertion of the blade. Once you see the larynx on the monitor then look at the monitor and glance back at your patient. The same is true when inserting your endotracheal tube. Failure to look at your patient during key moments can cause injury and broken teeth.
- Insert the blade in the midline and avoid inserting it too deeply, hiding the larynx.
- Ensure the tip of your ETT is in the same plane as the glottis.
- When having difficulty, lift the jaw, ask for cricoid pressure, or reposition the head and head as with any intubation.
- Lee JH, Park YH, Byon HJ, et al. A comparative trial of the GlideScope video laryngoscope to direct laryngoscope in children with difficult direct laryngoscopy and an evaluation of the effect of blade size. Anesth Analg. 2013;17(1):176-181.
- Armstrong J, John J, Karsli C. A comparison between the GlideScope video laryngoscope and direct laryngoscope in paediatric patients with difficult airways—a pilot study. Anaesthesia. 2010;65(4):353-357.