A 55 year old man was found unconscious in the bathroom by his family. He has a GCS of 7. His vital signs on arrival are a heart rate of 130, a blood pressure of 90/55, a respiratory rate of 28, and an oxygen saturation of 89% on room air. After using basic airway maneuvers to temporarily stabilize his airway, you were able to take the time to appropriately resuscitate and pre-oxygenate him. His vital signs are now a heart rate of 105, a blood pressure of 122/77, a respiratory rate of 16, and an oxygen saturation of 100% with a non-rebreather set at flush rate and nasal prongs at 15 L/min. However, he remains unconscious and you think it is now time to proceed with intubation…
As was discussed in the last post, before starting with RSI it is important to consider if the patient is physiologically ready for intubation. After appropriate resuscitation and pre-oxygenation, we can start with the procedure of intubation.
Consider the anatomy of the patient
A lot has been written about predicting the anatomically difficult airway. We probably aren’t as good at prediction as we would like to think, and parts of the classic anesthesia exam aren’t feasible in the emergency setting, but I am not going to get into that debate. (Levitan 2004; Soyuncu 2009) I approach every single airway with the mindset that it will be potentially difficult to pass the tube.
However, using a systematic approach for the assessment of airway anatomy is a good way to remind yourself that RSI is not the ideal approach for all patients. I like the LEMONS assessment: (Braude 2009)
- L: Look externally
- E: Evaluate 3-3-2 rule (mouth opening at least 3 fingers, distance from tip of chin to hyoid bone at least 3 fingers, distance from hyoid bone to thyroid cartilage at least 2 fingers)
- M: Mallampati score
- O: Obesity/ Obstruction
- N: Neck mobility
- S: Saturation (oxygen)
This systematic assessment is supplemented by the most powerful tool at our disposal in emergency medicine: gestalt.
When the anatomy or pathology predicts a particularly difficult airway, ask: does this patient need a tube right now? If the patient is stable, call for extra help and consider using alternative techniques to RSI, such as awake intubation or planned, awake, urgent tracheostomy. (Apfelbaum 2013) If the patient is unstable, or rapidly evolving, you will often have to make your best attempt, with a planned early transition to a surgical airway.
When potentially difficult anatomy or pathology is identified, but I still think that rapid sequence induction is preferable to awake intubation, I will mark the cricothyroid membrane with a marker. This is not because I think that mark will actually help with the procedure, but because I hope it will help me and my team overcome the significant cognitive hurdle associated with performing a surgical airways. (Leeuwenburg 2015; Cook 2011; Frerk 2015)
Check equipment (use a checklist)
I like physical checklists a lot, because when I have a critically ill patient in front of me, I don’t want to be using my limited brain cells to try to remember what equipment I need. Jaber (2010) showed how a simple checklist for endotracheal intubation used in four critical care departments could decrease complications by 50%. My favourite checklist has a visual layout of the equipment, so that you can actually see what you have and what you are missing, such as this one from my friend Casey Parker at Broome Docs. (Leeuwenburg 2015)
There are many other checklist options, a number of which can be found in the links at the bottom of this post. The EMCrit RSI checklist is excellent and covers the entire intubation procedure, not just the equipment.
If you don’t have a printed checklist, the SOAP-ME mnemonic is often taught as a way to remember the essential equipment:
- S: Suction
- O: Oxygen
- A: Airway equipment (laryngoscope, multiple blades, multiple sizes of ETT, stylet and backup options, syringe, bougie)
- P: Pharmacology (induction agent, paralytic, ongoing sedation, vasopressors)
- M: Monitors
- E: End tidal CO2
Decide on your drugs
RSI medications are one of the most hotly debated topics in emergency medicine. I cannot possibly cover the entire debate here. I think the most important point is to be intimately familiar with any medication you will use when managing the airway of a critically ill patient.
There is not one ideal induction agent. The agent I use most frequently is ketamine, because of its relative hemodynamic stability, rapid onset but prolonged action, and provision of both analgesia and sedation. For patients in whom I want to avoid tachycardia and hypertension (e.g. aortic dissection), and in status epilepticus, I tend to favour propofol.
For hypotensive patients (or patients at risk of becoming hypotensive) etomidate and ketamine are the most commonly used medications. However, it is essential to recognize that all of the drugs we use can result in hemodynamic instability. The dose of the agent chosen is probably more important than the actual agent used. For patients in shock, use much lower doses than usual, and titrate up as necessary. As a general rule, half the induction drug and double the paralysis dose. For a more in depth discussion on the topic, refer to Scott Weingart’s talk.
There is also a lot of debate about paralytics, but I think either succinylcholine or rocuronium is fine. There is some evidence that succinylcholine, presumably due to fasciculations, results in a shorter time to desaturation, so in patients at high risk of desaturation rocuronium might be a better choice. (Tang 2011; Taha 2010) Otherwise, I decide based on whether there are contraindications and how long I want the patient to be paralyzed. When using rocuronium for RSI, a dose of 1.2-1.5 mg/kg should be used to obtain similar intubating conditions to succinylcholine at 1 minute. (Tran 2015)
There is a quick summary of the commonly used airway medications here.
Inform the team of your plan
There are a lot of different airway algorithms. I have my favorite, which I will discuss below, but you might choose another. More important than the specific algorithm, in my opinion, is verbalizing the plan to the room and sticking to it. (Frerk 2015; Brindley 2017)
Position the patient
Take the time to position the patient before making at attempt at intubation. Most patients should already be positioned appropriately because the best position for intubation is also usually the best position for preoxygenation. Obese patients in particular may require ramping to achieve the classic ear to sternal notch position. There is pretty solid and consistent evidence that elevating the head of the bed improves preoxygenation and prolongs safe apnea time. (Frerk 2015; Ramkumar 2011; Altermatt 2005; Dixon 2005; Boyce 2003) However, there is also evidence that intubating with the head of the bed elevated might improve glottic views and decrease complications of emergent intubations. (Lee 2007; Khandelwal 2016)
Avoid desaturation during intubation
Despite the recent negative RCTs, I currently use apneic oxygen for all emergency department intubations. (Mosier 2015; Sackles 2016; Caputo 2017: Weingart 2012; Apfelbaum 2013; Frerk 2015) I use regular nasal prongs set at 15 L/min, left on the patient throughout pre-oxygenation, apnea, and intubation attempts. (Frerk 2015)
Push the drugs and wait
A key component of RSI is not providing ventilations during the apneic period to reduce the risk of aspiration. (Update: After the PreVent trial, more people are routinely providing ventilations during the apneic period. I am still selective in who I ventilate. If you are using a BVM, make sure you are using good technique, so you don’t inflate the stomach.)
Push your drugs and have patience. You will not have ideal intubating conditions until 45-60 seconds after medication administration. Occasionally, there are patients who will require ventilations throughout the procedure, such as patients with severe metabolic acidosis. These patients will have been identified during your pre-intubation resuscitation.
Take it one step at a time
- Find the uvula to orient yourself to the midline.
- Epiglottoscopy: Slowly move the laryngoscope blade down the tongue until the epiglottis is visualized. This step really shouldn’t require any force.
- Laryngoscopy: Once you have seated the blade in the vallecula, you can apply some force to lift the head. This is the time to ensure you have adequate control of the tongue, moving it to the side to provide you with the space you need for tube delivery. Add bimanual manipulation if necessary. (Use your right hand to move the larynx into the position that provides you with the best view and then have an assistant maintain that position). If you are using a hyper-angulated video laryngoscope (like the glidescope), the goal shouldn’t be to fill the screen with a beautiful view of the cords. Pull back on the blade, leaving the cords in the top third of the screen in order to provide more space to facilitate tube passage.
- Tube delivery: With traditional direct laryngoscopy, you don’t need to have a huge bend in the endotracheal tube. Light travels in a straight line, so if you can see the cords, the tube primarily has to travel straight. (Obviously, this is not true with video devices.) The slight bend in the tube is so that you can keep it below your line of site and enter the cords from below. Use the right side of the mouth so avoid interference from the teeth, and have an assistant pull the cheek to provide more room if necessary.
- Confirm placement: Use end-tidal capnography. There are other options that I will add, such as observing bilateral chest rise, auscultation, and ultrasound, mostly to rule out right mainstem intubation, but quantitative end-tidal CO2 is the gold standard we should all be using to confirm ETT placement. (Apfelbaum 2013; Frerk 2015)
- Secure the tube
A failed airway algorithm
The goal in every intubation is rapid first pass success. (Bernard 2015) You should expect first pass success 85-90% of the time. (Park 2017) However, I approach every airway assuming that my first pass will fail, with a focus on clear back-up steps. There are many different airway algorithms, and each has it’s own positives and negatives. Personally, I like the Shock Trauma algorithm used by Scott Weingart because it is simple and rapidly moves me forward with each step. This is very similar to the Difficult Airway Society algorithm. I will provide links to other algorithms below.
Intubation attempt number one can use any technique you like (although there is reasonable evidence to use a bougie on the first attempt). If that fails, you must change something (e.g. blade, tube size, bougie use) for attempt number two. (Frerk 2015) (I, like Scott, start with a standard geometry blade, and will switch to a hyperangulated video technique for my second attempt.) A third attempt at intubation, again with a change in technique guided by the previous attempts, is allowed. Limit laryngoscopy to 3 attempts. (Frerk 2015) However, after even two failed attempts, unless there is a clear correction to be made, I will often proceed directly to inserting an LMA. (Ideally, you want to use a second generation LMA that will allow subsequent intubation through the LMA using fiber optics.) (Frerk 2015) If you cannot oxygenate using the LMA, or rescue BVM, then proceed directly to a surgical airway.
Things to consider changing between laryngoscopy attempts:
- Video vs direct laryngoscopy
- Different blade
- The patient’s position
- External laryngeal manipulation
- Different tube
- The person intubating
- Adding adjuncts such as a bougie
The rest of the airway series:
Part 3: Intubation
A special thanks to Dr. Laura Duggan (@drlauraduggan) and Dr. Casey Parker (@broomedocs ) for providing peer review for this post. Be sure to check out the airway app designed for reporting cases of front of neck airway access, as well as the 3D printed Cric trainer by Dr. Duggan: http://www.airwaycollaboration.org/
Although we spend a lot of time focusing on the anatomical problems, and to a lesser extent the physiological problems, encountered in managing airways, Cliff Reid reminds us that the most important problems to consider are often situational difficulties. The Difficult Airway Society specifically starts their guideline by discussing human factors. (Frerk 2015) You can read my post about performing under pressure here. The paper by Brindley (2017) also does a great job of considering some of these difficulties in the specific context of managing the airway.
There are many different algorithms for managing difficult airways. You can find the Difficult Airway Society (DAS) algorithm here. There is a nonlinear algorithm called the vortex approach that you can read about here.
You will notice that I did not mention the debate between video and direct laryngoscopy at all in this post. I love both. I think both are reasonable approaches. I think we all need to be able to use both in our practice. I don’t care which technique you decide to start with, as long as you are comfortable with the other as a backup option. If you want more on this topic, I would suggest this excellent editorial by George Kovacs and John Adam Law.
Other FOAMed Resources
Best Look Laryngoscopy
More Laryngoscopy Tips via Scott Weingart
Rapid Sequence Intubation
AIME VL Pearl: Not so close
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