Advanced airway modalities (part 4)

[jagdkampf]

This is where stuff gets really interesting. Most of the techniques listed here are outside of the scope of most lay providers but some state allow EMT's and paramedics to perform them in the field.

(1) endotracheal intubation -- as the name implies, this is a very straight forward technique. You are simply inserting a tube into the trachea by which you may ventilate the patient. How you do this can vary a bit though. The most direct route is through the mouth by means of a laryngoscope and blade. A laryngoscope is a battery powered instrument that incorporates a light or lighted blade by which you can see structures deeper in the throat than by just looking in the mouth with the naked eye. There are several different sizes and shapes of blades that attach to the laryngoscope and the choice of which to use is primarily driven by patient size and provider preference. The 2 main types of blades are the straight (Miller, Phillips, Wisconsin or Wis/Foregger) and the curved (Macintosh). There are also a couple of speciality laryngoscopes that incorporate a fiberoptic vision channel, i.e. the Bullard laryngoscope. These are just a few of the many different types. From a practical standpoint you should become familiar with 1 type of straight blade and the Macintosh blade. The curved Macintosh tends to follow the anatomy of the oropharynx better and if used correctly tends to be less traumatic on the oropharyngeal tissues but it also has a larger profile and can damage teeth if used incorrectly. The straight blade requires a little more dexterity to use but has a slimmer cross section. If the patient has a Mallampatti score of 2 and less than 2 penalty points (see earlier thread on the difficult airway), I prefer the Macintosh. If the patient presents with a higher score, I consider the straight blade or awake fiberoptic assisted intubation.
Children and infants are best served by a straight blade as certain anatomic considerations make the Macintosh a bit more difficult to use, although not immpossible. My personal preference is the Robert Shaw blade on children and infants.
Adults are generally served by 2 sizes. Adult males-- #4 straight or curved.
Adult females-- #3 straight or curved.
Children/infants--The blade length should be the same as the distance from ear lobe to the corner of the mouth. Generally, this is a #0 in infants, #1 in children up to age 3, and a #2 thereafter until age 10.
One item that is handy to have along with the laryngoscope and blade is the stylet. This is a malleable rod roughly as long as the endotracheal tube. The rod is inserted into the endotracheal tube to make it more ridgid or to preform it to a certain shape. In difficult airways, practicioners will sometimes preform the tip of the endotracheal tube with the stylet inserted to resemble a hockey stick.

Since these techniques are a little more advanced, I will stop after each one to address questions or comments. Anybody have any?
Jag

[tangent]

please define "Mallampatti score"

[Reasonable Rascal]

My favorite choice in blades is a #4 Wisconsin - always nice the see the eyes of onlookers open wide when they see you pull that out. :eek:

On the subject of stylets, what is your preference, malleable copper wire or the vinyl coated thinner and stiffer wire such as offered by Promed in their SlickSets?

And for the beginner, does handle choice - adult C-cell size vs. peds AA-cell size - matter as far as the learning curve?

RR

[tangent]

as a beginner in this area, I'll stress a very important point - probably not applicable to everyone: give me the AA anyday! and preferably in something I can use as a multipurpose device! - I gotta carry the damb thing on my back! and I'm counting OUNCES!

[jagdkampf]

Q1 -- Mallampatti Score, see the earlier post on the difficult airway. It is a gradient scale which assesses the airway based on anatomic factors. Named after a Doctor Mallampatti I believe.

Stylets -- I use a satin finish plasticoated aluminum stylet. No problems with it so far.
Occasionally, I have to whip out the escheimann (sp) stylet. More on that later.

Handles--Whatever best suits you. I use a C battery handle but then I don't have to pack it 20 miles into the outback. I guess it's sort of like the old "paper or plastic", no big deal to me. Most of my blades are fiberoptic. I am sort of ambivalent about them. They are nice till they go bad but then they are harder to replace and more expensive than a simple bulb swap.

Keep those questions coming!
Jag

[jagdkampf]

Continuing on with advanced airway modalities.
Endotracheal intubation by indirect means

(1) Light wands -- The light wand is a lighted stylet. The long slim stylet has a bulb at one end and a battery operated handle at the other end. Intubation is accomplished by inserting the stylet portion into the endotracheal tube until the light is at the tip. The endotracheal tube is then preformed to form a curved C shape. The index and middle fingers are inserted into the patients mouth with the palm facing the lower jaw. The endotracheal tube/sylet is guided into the oropharynx between the index and middle fingers with the C shape following the anatomic curve of the throat and directed toward the midline. You should be able to see the glow of the bulb as the tip enters the trachea. If the tube has been advanced an appropriate distance and no glow is seen then the tube/sylet is redirected until this is accomplished. Once the glow from the bulb is seen in the midline of the trachea, the tube is advanced an appropriate distance (adult females - 21cm, adult males - 24 cm) then the sylet is withdrawn and the cuff inflated. Breath sounds must be immeadiately checked for placement of the tube.
This technique has a couple of disadvantages. It does not work well in direct sunlight or highly lighted environments and works best in subdued lighting. It requires some practice and dexterity to make it work quickly. With multiple attempts it traumatizes the oropharynx and trachea, producing blood and secretions.

(2)Escheimann stylet--Although I am classifying this as an indirect means, it is intended to be used as an adjunct with direct oral laryngoscopy (direct veiwing of the posterior throat and structures with a laryngoscope).
The Escheimann stylet is a long vinyl/platic covered piece of parachute cord that has one end preformed to resemble a hockey stick. The plastic coating makes the parachute cord stiff but malleable. To use the stylet, the practicioner uses a laryngoscope to visualize the structures of the throat. The stylet is gently used as a probe until it advances into what the practicioner believes is the trachea. After, the stylet is advanced into the trachea, the laryngoscope is withdrawn leaving the stylet in place in the trachea. Then a well lubricated endotracheal tube is advanced over the protruding end of the stylet and into the mouth. Grasping the protruding end of the stylet and holding it firmly in place, the endotracheal tube is slowly advanced with a gently oscillating motion following the Escheimann sylet into the trachea to an appropriate depth as previously stated. The stylet is then withdrawn and the cuff of the tube inflated and tube placement checked by listening to breath sounds.
This is a particularly handy device to have for difficult airways, where direct visualization of the vocal cords is not possible. One of these devices resides on my cart and has had multiple uses. They are very durable and weigh next to nothing so they would be very good for field usage.
The only disadvantage I can see with their use is that they require a bit of practice and dexterity to use. I highly recommend this device.

Ok, I will pause here for questions.
Jag

[tangent]

Jag,

for everything you've written here, could you elaborate on how a known or suspected c-spine injury is going to alter how these techniques are done and which ones it may rule out?

along the same lines, is there a suggested cource of what should be tried first, second, etc. and which are a matter of preference, but roughly equivalant?

[jagdkampf]

Suspected C-spine injuries will change the approach to some degree. That being said, the airway is of vital importance and should be given first consideration. The ideal approach to suspected c-spine injury management requires a 2 person approach. The first person provides what is called "in line axial stabilization", this is just a fancy phrase for keeping the head and c-spine in a neutral position while minimizing c-spine movement. The second provider actually does the airway management. Typically, airway management in critical injuries must be done prior to c-spine stabiliztion on a backboard, c-collar, etc. Every tried to intubate someone on a backboard with a c-collar on and secured with about 5 roles of duct tape? Not an easy propostition. A good deal of common sense is required for c-spine injuries. Granted, you don't want to paralyze an individual with negligence but neither do you want them to die from lack of ventilation.
As far as the order of treatment, my general rule is "do what is necessary at the time". My job requires me to have multiple airway skills. Therefore, I perform and practice a lot of different techniques. I am also in a facility where things are as optimum as you can get for securing an airway. Things are entirely different in the field as you well know. Simplicity is probably the best approach (KISS). If I were a medic in the field, I would try to narrow down my options to 3 airway systems progressing from minimally invasive to invasive. My preference would be as follows:
(first line treatment)- oral airway with pocket mask
(second line treatment)- combitube,laryngoscope and eischmann stylet.(third line treatment)- emergency cricothyrotomy kit, preferably the "Melker-Cook Emergency Cricothyrotomy kit"

You will notice that there is no endotracheal tube in this listing. I would probably put a laryngoscope in with my combitube and if I could do laryngoscopy, I would just use the combitube as an ET tube.

These discussions are really just an overview as to what is available. Some of these devices are totally impractical for field use. I think I will start an interactive thread on case management. If you think it would be helpful, join in, if not just kick it off the board.
Jag

[RESQDOC]

Ditto Jag. Great info.

Endotracheal intubation is the gold standard, but I am quite happy with the Combitube also.

The Melker-Cook cric kits are nice but I just cobble mine together, cheaper that way.

There are a variety of over the stylet intubation options, all are good tools to have in your bag of tricks.

My favorite is over the wire retrograde placement via cric with intubation then down over the wire. I have done this twice in the field on mangled airways with near total loss of anatomy, and in the hospital several times, works well for me.

[RESQDOC]

A Pilot Study Comparing the Ease of Intubation over an Eschmann's Stylette of the Parker Vs. the Mallinckrodt Endotracheal Tubes
Fernando A. Gutierrez, M.D.; John Stene, M.D.; H. Gregg Schuler, B.A.; Wade Weigel, M.D.

Anesthesiology, Pennsylvania State University, Hershey, Pennsylvania, United States

Introduction: The Eschmann stylette is a very useful aid to difficult intubations; however Murphy tipped endotracheal tubes frequently get caught on the hypopharynx, epiglottis or arytenoids, causing difficulty in threading the tube over the stylette. A new endotracheal tube (Parker Flex-Tip®) is designed to easily glide through the glottic opening over a gum elastic bougie or bronchoscope. We compared the ease of intubation over an Eschmann stylette between the Parker Flex-Tip® and a Murphy Tip tube (Mallinkrodt®). Methods: Following IRB approval, adult subjects scheduled for general anesthesia were prospectively enrolled in a randomized blinded study. All subjects consented to participating. Aspiration risk and anticipated difficult intubation by physical exam were exclusion criteria. The patients were randomized to one of two groups. The primary anesthesia provider chose induction technique and tube size. After direct laryngoscopy an Eschmann stylette was placed in the trachea. A Parker® or a Mallinkrodt® ETT was placed over the stylette. The anesthesiologist, who was blinded to the type of tube, was asked to slide it over the stylette into the trachea. A form containing a 10 cm Visual Analog Scale (VAS) to describe the difficulty of the tube placement was then completed by the anesthesiologist. The time to perform the intubation was recorded. We also recorded if the ETT went in on the "First pass" or not and what adjustments had to be made. Patients were questioned the day after surgery for symptoms of sore throat or hoarseness. Results: 23 patients were enrolled, 11 in the Parker® group and 12 in the Mallinkrodt® group. Demographic characteristics were similar. The Visual Analog Scale and required time results are presented in the figure: All of the 7 tubes reported as "Not first Pass" were Mallinkrodt® (For a "Hang up" incidence of 58.3%). In addition they were all 8.0 size tubes. All of the Parker® tubes went in as a "First Pass" including all the 8.0 sizes. The overall incidence of side effects in our study was small, and there was no difference between groups. Discussion: When attempting to advance a Mallinkrodt® ETT over an Eschmann stylette there is a high probability of the tube getting caught requiring adjusting maneuvers to reach the trachea. This probability is significantly reduced with the use of the Parker® tube (Fisher's Exact Test, p=0.0046), making it easier to intubate the trachea. There appears to be a correlation with the size of the ETT and the difficulty in advancing it. Based on this study we recommend the use of Parker® Flex-Tip ETT when performing a tracheal intubation with the aid of an intubating stylette (i.e.: Eschmann, Bronchoscope, etc.)

Anesthesiology 2001; 95:A595

Click to view associated image.


2001 ASA Meeting Abstracts.
Copyright © 2001 American Society of Anesthesiologists. All rights reserved
Published by Lippincott Williams & Wilkins

NOTE: I have not tried the Parker tubes yet, but am going to order a few.

[jagdkampf]

I have used the Parker tubes and they are sweet. They work particularly well for nasal intubations. Try'em - you'll like them.
Jag