|
Airway Q&A
Atomizers and Topical Airway Anesthesia
Question: Dr. Morris, I attended your lecture at the difficult airway course a few years ago. Since then, I have converted to your technique of using 3% Lido for airway anesthesia prior to awake fiber optic intubation. Unfortunately, my hospitals no longer have DeVilbiss atomizers and I am always forced to improvise. I may have convinced them to order one. I wanted to get your opinion on this. Would you be so kind as to look at the Micromedics web site, Atomizer 151? That looks to me to be the best alternative because:
1. It looks like it's completely autoclavable (although delicate).
2. It is readily adaptable to your technique of O2 tubing with a port for occlusion.
Also, I want to ask you these questions about your technique. What is the average amount of 3% that you use via the atomizer (in cc's) and on the Jackson forceps, etc., and have you done any studies looking at peak levels of drug during your procedure? Thanks in advance. I learned a lot from your lectures.
Answer: (From Ian R. Morris, MD) I am glad that you found our techniques helpful. I did visit the Micromedics website. The atomizer #151 is actually a Devilbiss according to the description. I do not have experience with this particular device. The DeVilbiss #15 which is in the next panel of the product page is the device we use. I'm surprised that your hospital would have issues with this device. It is probably the most cost effective piece of equipment that we use. We have never had an issue with its sterilization. The DeVilbiss #151 looks like it may not be as stable when placed on a prep table due to its narrow base. From its description it would probably be satisfactory with our technique, although I would recommend the #15.
We have never measured lidocaine blood levels with our technique. It is difficult to get this test in our institution and I suspect that it is not cheap. We have never had a toxic reaction with lidocaine with our technique.
My standard technique is: 5% lido ointment applied to the posterior third of the tongue using an amount of ointment about the size of my thumbnail and about 1-2 mm thick on a tongue depressor. Only a portion of this amount is actually administered. I then use the DeVilbiss atomizer and usually administer about 12-13 ccs of 3% lidocaine. I then do an internal approach SLN block using Jackson forceps and cotton pledgets soaked in 4% lidocaine. The pledgets are soaked but not dripping. Again, only a portion of the amount of lidocaine in the pledgets is administered. I have not weighed the amount of lidocaine administered using the ointment or pledgets but this could be done.
I have recently exhaustively reviewed the topic of topical airway anesthesia and updated Chapter 3 in the upcoming second edition of Management of the Difficult and Failed Airway. I have summarized multiple articles on this topic and leave it to the reader to decide the most appropriate technique and the most reasonable maximum doses based on the available evidence. As you may know, the British Thoracic Society has recommended that 8.2 mg/kg of lido not be exceeded during bronchoscopy, and that this dose be reduced in the elderly and those with relevant comorbidities. Hope this is helpful.
Use of Paralytic with Rescue Airway Confirmed by Capnography
Question: Our state protocol for failed RSI intubation in which a rescue airway was used (Combitube, LMA or King) that was confirmed by capnography, calls for post-intubation management. Post intubation management under the protocol is for a long term sedative and long term paralytic (in our case versed and vec.). Are there any contra-indications for using a long term paralytic with a rescue airway that is confirmed by capnography?
Answer: (From Aaron Bair, MD) Regarding the use of long term paralytics after the placement of an extraglottic device, I am not aware of any prehospital evidence either way.
In our region, our prehospital protocols do not use paralytics in this context. This is presumably because the patient does not need chemical paralysis due to the previously given RSI meds or they are obtunded to the point that it is just not necessary.
However, I could also see that fully sedating and paralyzing a patient for transport would potentially make the transport easier to manage. I would just worry that the use of paralytics without a definitive airway could get dicey if the extraglottic airway becomes dislodged (though presumably continuous capnography would help detect this issue).
Answer: (From Ron M. Walls, MD) The overall trend nationally is toward increasing use of sedation and analgesia and minimizing use of paralytic agents for post-intubation management, but the issues in EMS are very different because of the threat presented by a mobile patient in a fixed space. Overall, I agree with Aaron. There is no real evidence, but Combitubes and LMAs are used for elective general anesthesia all over the world (Combitube more in Europe). So, provided appropriate caution is used to secure the tube and that sedation and paralysis are managed as for an ETT, I see no problem with it. The real key for me would be to be confident, while the drugs for RSI are still on board, that ventilation/oxygenation will indeed be successful.
For further discussion on this subject, click here.
Cricoid Pressure
Question: I attended The Difficult Airway Course a couple of years ago and I am currently preparing a lecture for my emergency medicine residents. I had some difficulty finding this answer in a lit search. When cricoid pressure is being applied and a patient vomits, would you recommend relaxing the cricoid pressure or maintaining it? I have heard both sides of the argument and wanted to see what your take on it would be.
Answer: (From Ron Walls, MD) We have actually ceased recommending routine use of cricoid pressure (Sellick Maneuver) effective in the third edition of our books and our 2008 and onward courses. We feel that there is insufficient evidence to argue for, or against, its use, but that its tendency to worsen glottic view accompanied by its lack of demonstrated benefit relegate it to “optional” status, at best. This is covered in the textbook (Walls RM and Murphy MF: Manual of Emergency Airway Management, 3rd edition, Lippincott, Williams and Wilkins, 2008). There was also a review article in Annals of EM in December 2007.
In any case, there has been no study related to releasing Sellick when vomiting occurs, but belief is that it might cause esophageal rupture. Vomiting is not really an issue in the context of RSI, because the neuromuscular blockade precludes vomiting.
Interesting Airway Case
Question: I am an Emergency Medicine staff physician in Calgary, Alberta and work with our air ambulance system here as well. I recently had an interesting airway case and tried something new which worked beautifully. The case and management is described below and I would be interested in what you think of my thought processes and if you have ever had success with this before.
Case: Obese 60 something male, found down, ? etiology, home O2 and COPD history. EMS arrival = hypoxic and GCS 3, attempted. Intubation with RSI = unsuccessful after multiple attempts secondary to poor visualization. LMA placed and transported to ED. Hypoxia improved. In the trauma bay = Sats maintained with LMA and BVM ventilation. Patient fully ventilated. LMA leaking badly with ventilation.
Plan was to capture airway. Instead of just pulling out the LMA and proceeding down the difficult airway management algorithm, a bougie was placed down the LMA prior to its extraction. The LMA was removed, direct laryngoscopy was attempted to identify where the bougie was. No visualization possible. Bougie felt in the right place based on manipulating bougie in larynx. A well lubricated ETT tube was placed over bougie and confirmation of tube placement ensued. Success! A potentially difficult airway turned into a really easy airway with the help of not burning any bridges by simply placing a bougie down the LMA prior to its removal.
I have always thought this would work, but have never read about it in any of my studies or seen it done. My feeling is that this should be common practice when faced with a patient who has an LMA in place, requires a definitive airway and has predictors of difficult intubation. Absolutely nothing is lost by attempting this and it could really save time and potentially avoid a surgical airway.
Answer: (From Ron Walls, MD) Great work! This is a classic example of thinking ahead; and "don't burn your bridges" is a favorite admonition of my friend and colleague, Mike Murphy.
There is a small literature on intubating through the LMA or ILMA with the ETT (yes, you can intubate through a conventional LMA with a conventional tube about 80-85% of the time vs 95% for ILMA, primarily because the epiglottis gets in the way in some cases), a fiberoptic scope, a lighted stylet (Trachlight), or any kind of conventional stylet or bougie.
In addition, I would offer the following:
1. The "leak" was probably because of the relatively low seal pressure (about 20-25 cm H2O) for the LMA versus the high pressures required to ventilate the obese patient. This might be helped by placing the patient in reverse Trendelenberg (to get the pannus off the diaphragm) and ventilating with a lower inspiratory flow rate.
2. A reasonable next step might have been attempted intubation through the LMA (assume this was a conventional, not intubating, LMA, but worth a shot!)
3. Your bougie placement was inspired, but remember that mismatch between bougie size and tube size (use the tube that is the closest "fit" possible over the bougie) and the lack of support of direct laryngoscopy (direct laryngoscopy is continued while intubating over the bougie, not just while placing it) to help open things up so the tube can clear the arytenoids, both set up for trouble at that level. You got it in, though, so great work!
Answer: (From Mike Murphy, MD) That was good thinking. The technique you employed has been described in the past, but in the anesthesia literature (Ahmed AB, Nathanson MH, Gajraj NM. Tracheal intubation through the laryngeal mask airway using a gum elastic bougie: the effect of head position. J Clin Anesth. 2001 Sep;13(6):427-9.), but I cannot find a citation in the EM literature so you ought to consider publishing it.
The use of a bougie to place an LMA is well described and is well known in anesthesia (Howath A, Brimacombe J, Keller C. Gum-elastic bougie-guided insertion of the ProSeal laryngeal mask airway: a new technique. Anaesth Intensive Care. 2002 Oct;30(5):624-7. Brimacombe J, Keller C. The ProSeal laryngeal mask airway: A randomized, crossover study with the standard laryngeal mask airway in paralyzed, anesthetized patients. Anesthesiology. 2000 Jul;93(1):104-9. Cook TM, Silsby J, Simpson TP. Airway rescue in acute upper airway obstruction using a ProSeal Laryngeal mask airway and an Aintree catheter: a review of the ProSeal Laryngeal mask airway in the management of the difficult airway. Anaesthesia. 2005 Nov; 60(11):1129-36.) so among practitioners, the notion that two rescue techniques might be used in combination is not unusual.
The approach of combining rescue techniques HAS been described in the EM literature: Kovacs G, Law JA, McCrossin C, Vu M, Leblanc D, Gao J. A comparison of a fiberoptic stylet and a bougie as adjuncts to direct laryngoscopy in a manikin-simulated difficult airway. Ann Emerg Med. 2007 Dec;50(6):676-85. However, having said all of that....great and quick thinking...you may want to publish it!
Procedural Sedation in Children
Question: I work in a small, rural hospital with variable skills among local doctors. Can you recommend a protocol or references for simple procedural sedation in children?
Answer: (From Nate Mick, MD) For procedural sedation in children, the following equipment is necessary:
1. Full cardiopulmonary monitoring (including sat, BP, pulse).
2. Capnography (allows breath by breath assessment of ventilation, gives lead time when apnea occurs prior to desaturation, allows you to tell between apnea and laryngospasm)
3. Rescue airway equipment (BVM, endotracheal intubation tools)
4. Two people in the room with at least one physician; the person doing the procedure ideally isn't the one watching the monitors.
For drugs:
1. Ketamine (useful for most painful pediatric procedures) - caveat...a lot of relative contraindications, most notably, don't use for kids with active URI or asthma (increases risk of laryngospasm)
2. Fentanyl/Versed - useful for painful procedures when ketamine is contraindicated
3. Pentobarbital - great drug for sedation for imaging studies/other non-painful procedures
4. Propofol - if you can get it in the ED, may make Pentobarbital obsolete.
You may wish to peruse the 2007 ACEP clinical policy on Procedural Sedation in Children; it's a good starting point. If you need specific literature, anything written by Baruch Krauss, Steve Green or Joh Burton is good.
Succinylcholine in Pediatrics
Question: Recently a colleague of mine asked you a question regarding the use of Succ in the peds. population. I had raised this issue with him for a couple of reasons. A # of years ago, I attended a peds. ED conference at CHOP in Philadelphia where anesthesia had pulled succ. from their dept. and gave them roc. as felt to be a safer choice. Last year at the ACEP peds conference Tim Ericson stated that succ. is not a good choice as safer agents available. I continue to use succ. as my initial choice unless contraindications exist. What are your thoughts on this point and the recent literature suggesting that atropine is not needed pre succ. in kids as no evidence to support this practice.
Answer: (From Bob Luten) This is one of those things that does not have specific literature defining or not defining a preference between sux and really the only other choice, rocuronium, in children. Both are used and preferences are personal. The rationale for choosing roc over sux has to do with the perceived safety of the drug given the fact that the FDA warned against the use of the drug in children after a couple of reports of hyperkalemic cardiac arrest following administration of Sux to patients with undiagnosed neuromuscular disease approximately 10-15 years ago. The pediatric anesthesia community at that time rebelled against the FDA’s warning causing a softening of their stance to a caution. The incidence of that rare problem vs. any problems that could be encountered because of the long duration of action of Roc vs. sux is probably the crux of the issue. I personally use sux and promote it in the airway course in effort to keep things simple because it is recommended in adults. I have absolutely no issue with use of Roc however.
The issue of using atropine or not prior to Sux is another issue which cannot be definitively solved in the literature. Classically it has been used to prevent the bradycardia and even asystole which can accompany a single dose of sux in children. A few recent studies failed to show difference in response to sux with or without atropine in children. Admittedly it would be difficult to prove that the atropine is beneficial, but the absence of evidence is not proof when dealing with very uncommon event. If atropine were a dangerous drug, I would be more concerned. I routinely use the drug prior to the administration of sux as well as some of my anesthesia friends Charlie Cote’, author of a major pediatric anesthesia text thinks not using it is playing with fire, as he has personally had patients become asystolic after sux without atropine requiring resuscitation.
Using Resuscitation Bags for Preoxygenation
Question: I attended a Difficult Airway Course: EMS several years ago and at that time, Dr. Murphy advocated that only Bag-Mask resuscitators using disc valves, not duckbill valves, should be used for preoxygenation due to the greatly increased valve resistance. At the more recent course, this was not the case and duckbill valves were strongly advocated. In both the third and second editions of Manual of Emergency Airway Management, this reference to duckbill valves exists. The referenced paper, by Nimmagadda, seems to indicate that the most important factor in delivering a high FiO2 in the spontaneously breathing patient is the presence of a one-way exhalation valve.
Answer: (From Ron Walls) That is correct. Although disk valves were superior in the past, modern duckbill valves, as long as there is no ability to inhale from the room (i.e. the one way exhalation valve), are fine for pre-oxygenation. If you want some idea of how little pressure it takes to open the valve, try one yourself.
Trachlight for Nasal Intubation in Apnea
Question: The traditional teaching is that blind nasal intubation is contraindicated in apneic patients due to inability to assess alignment of the tip of the endotracheal tube with the glottic opening. It seems reasonable that in this case, assuming bag-mask ventilation is successful, that a Trachlight with the rigid stylet removed, possible in combination with an Endotrol tube, would be a reasonable approach.
Answer: (From Mike Murphy) I use the Trachlight routinely in doing apneic nasal intubation. However, I have done thousands of trachlight intubations and feel very comfortable with the technique. I do not feel that it is a technique to recommend to those with little experience in the nuances of trouble shooting a failed attempt. In the setting of the failed airway in an apneic patient, I stick with the recommendations to move to a cricothyrotomy concurrently with trying an EGD.
ENK Flow Modulator
Question: At the course, the ENK Flow Modulator was a recommended device. In the third edition of the text, Figure 16-17 shows this device and seems to imply that it is connected to high-pressure oxygen and not regulated, though my understanding is that it is intended to be connected to a flow meter to reduce the pressure. Is this device recommended, and in what age groups?
Answer: (From Nathan Mick, MD) The ENK Modulator is designed to attach to the flow meter (the "Christmas Tree”) and not the unregulated wall unit (which flows at 50 psi). The flow meter has an upper limit of 15 liters/minute (roughly 1 psi) so has a better safety margin. The ENK is an alternative to Bob Luten's recommended percutaneous needle cric/trach approach using the adapter to a 3-0 ETT and the pediatric BVM. It is appropriate for use in any child who is getting a needle in the neck. Please, if you ever do the procedure, write and tell us about it as experience in patients is limited.
Cricothyrotomy Equipment
Question: There was a comment about the preference for use of a blunt tracheal hook when performing RFST cricothyroidotomy. The Universal Kit, as shown in the text, includes a pointed hook. How much of an issue is this? Also, why was a No. 20 scalpel not included in the kit?
Answers: (From Ron Walls, MD) We don’t believe a number 20 scalpel is the way to go for a cricothyrotomy. It is much too big, and too easy to damage adjacent structures. The tracheal hook in the kit is sort of intermediate, i.e. not truly blunt, but not as sharply tipped as some are.
(From Aaron Bair, MD): Ron and I differ a bit on this issue. I am a believer in the RFST and for this particular technique I believe that the #20 blade is advantageous. The larger blade allows a single puncture of the cricothyroid membrane without the need for multiple smaller (potentially misdirected) incisions. Additionally, a sharp hook is only really useful for the No Drop (i.e. classic) cricothyrotomy technique as control of the thyroid cartilage is maintained by getting a “bite” of the cartilage. In contrast with the RFST cric, the hook is oriented in the opposite direction and is not intended to pierce any structures – it is only intended to lift the cricoid ring anteriorly. If no “bite” then no need for a sharp hook. For the RFST all you need is a hook and a scalpel; these I carry in a small case in my pocket. No boxed kit to locate. Fortunately, I have rarely needed to resort to an invasive airway. However, when it’s needed SECONDS count!
Identification of Difficult Video/Optical Laryngoscopy
Question: The LEMON mnemonic for indentifying patients in whom direct laryngoscopy is expected to be difficult is well backed by science and the test of time. With the proliferation of video and optical laryngoscopes suitable for emergency airway management, are there any markers that help in determining which patients will not be amenable to these approaches? Limited mouth opening is obviously still a challenge, as is obstruction, but the rest of the LEMON evaluation seems less useful if first pass videolaryngoscopy is planned.
Answer: (From Ron Walls) You are correct, of course. The rapid proliferation of video laryngoscopes and their ultimate large scale use in practice will require us to rethink difficult laryngoscopy. For example, a recent study in anesth analg tried to identify difficult markers for the glidescope, but if you read the paper, they successfully intubated 99.75% and all had a cormack-lehane of 1 or 2, despite a wide range of c-l scores for the same patients by direct laryngoscopy. Although the authors try to suggest what makes glidescope intubation “more difficult” it is clear that “difficult” becomes a highly relative term. We are thinking constantly about this, but the reality is that video laryngoscopy is going to eliminate much of our current concern about difficult airway.
Drug Administration via LMA
Question: I am a course director for ACLS in the Northern Illinois Region. I was wondering your thoughts on drug administration (code drugs) via an LMA. Since this is a "pre-cord" tube, do you risk losing your airway with drug administration?
Answer: (From Aaron Bair) By “losing the airway” do you mean dislodging the LMA or obstructing the lumen of the LMA with the medication? Regardless, I don’t think there would be a real risk of either. The issue to my mind would be failure to administer the medicine. With the LMA there is a bit of extraglottic space where the medication could pool without actually being delivered to the lungs. That said, I have never seen any studies on this nor have I had to contend with this situation.
Premature Infant Scenario
Question: Scenario question: 2 week premature infant is delivered. Spo2 is 97% on room air. Peds doc wants to intubate and give surfactant down the tube before transferring to an NICU. The anesthesiologist was unable to intubate. Could a #1 LMA be utilized for surfactant dosing one time, or again will this compromise the airway?
Answer: (From Aaron Bair) Again, I don’t think that I’d have an issue with administration of meds down the tube but would be aware of the issue of med loss (as mentioned above)…any port in a storm.
Romazicon in Emergency Room
Question: What are your thoughts on giving Romazicon in an Emergency Room to a known benzo OD? Do you support the airway only in case of seizures and let the drug wear off if you will?
Answer: (From Aaron Bair, MD) I would only give the reversal agent if I was the one who administered the benzo (e.g. an iatrogenic o.d. during a procedural sedation). The risk in an unknown ingestion is that you never REALLY know what the ingestion consisted of…The original studies of Romazicon use in the context of the “coma cocktail” ran into trouble with seizures. Evidently, this was an issue in mixed TCA ingestions and in people who were chronically treated with benzos for seizure control. The Romazicon then resulted in hard to control seizures, hypoxia and over-all badness.
Laryngoscope Light Intensity
Question: I was hoping that you could give me a contact to purchase a laryngoscope with a very bright light. It seems like the older I get, the lights on the laryngoscopes get more dull! Maybe it is just at my hospital but I would sure like to buy my own scope with a really bright light.
Answer: (From Aaron Bair, MD) I have attached a recent article that looked at the light intensity issue…I hope you find it interesting and helpful re: curved blade laryngoscopes.
That said, if bright is what you want you might ask your hospital to invest in a videolaryngoscope. The brightest laryngoscope that I have come across is the Storz Video Mac. Additionally, the GlideScope provides excellent imaging.
(From Mike Murphy, MD): We use Heine fiberoptic laryngoscopes and use the rechargeable handles...we have chargers in all of the OR's and immediately after use, we put them back in the charger. However, the Storz handles and lights are so bright that they enable the presbyopic to see! I'd replace all of our Heine's with the Storz if they were less expensive.
Fiberoptic Scope Brand
Question: I attended your course last year and have finally convinced my medical director of the importance of purchasing a flexible fiberoptic scope to use in our department for difficult intubations. I was wondering if you could recommend a specific brand/scope to purchase?
Answer: (From Aaron Bair, MD) Having gone through this process myself, I can recommend the following:
a. Make sure the scope is long enough. That is, get a bronchoscope so that you can actually intubate over it. I know colleagues who have been tempted by the shorter nasopharyngoscope but it is too short to easily intubate over.
b. You get what you pay for. I have had some experience with less expensive equipment and the image quality is poor and more importantly it BREAKS. If you're going to invest in this gear you have to realize that you are investing in a PROCESS. This involves the initial purchase, but cleaning and replacement/maintenance too. If you think the expensive part is done just with the initial purchase -- you'll be disappointed. We currently have a Storz intubating bronchoscope. It is fantastic.
c. Talk to your hospital colleagues. Find out what your hospital's pulmonologists and anesthesiologists are using. Sometimes an equipment vendor will have a "deal" with a given hospital so purchase is a little cheaper and easier. Also, familiarity with the company representative and various technical issues is important. No need to recreate the wheel on this if you don't have to.
(From Ron Walls, MD): I think Aaron has it nailed, but I have to add that Storz also has refurbished scopes available at about 1/3 the cost of the new ones, and they have been excellent. I agree also that an intubating bronchoscope is important. The smaller, shorter, more flexible scopes are wonderful for diagnostics, and you should have one of these, also (nasopharyngoscope), but for intubating, get a good size (3.2 mm or bigger) bronchoscope.
5% Xylocaine Paste
Question: I attended the difficult airway course in LA last week. I was impressed with Dr Ian R. Morris’ technique in awake fiber optic intubation. I want to ask where I can get the 5% Xylocaine paste the mentioned. I have asked the pharmacy at the hospital where I work and other hospitals in the area and they are not aware of such a lidocaine paste. Can you please give me the information on the company that makes such a product?
Answer: (From Mike Murphy, MD) Any pharmacist can compound a 5% ointment, but the following website is for a US distributor, Taro Pharmaceutical.
|