Second thoughts regarding rapid sequence intubation

Chief Editor note: This clinical paper raises an important dilemma for the practitioner. We expect comments and opinions from our readers.

Marcelo Ramos, MD
marcelosperiandoramos@yahoo.com

The most important decision in anaesthesia is whether to intubate BEFORE or AFTER induction. The basis of all the algorithms (and our beliefs) is that once we have defined that we can with “certainty and security” guarantee the ventilation (and/or maybe intubation), we can induce.

We propose and believe that whenever there is uncertainty or doubt about the ability to VENTILATE, the most prudent approach is to proceed with topical anaesthesia (with or exceptionally without) plus sedation (or exceptionally without) and perform the so-called “awake intubation” (ATI).

The recommended management of patients in whom a difficult airway is predicted is to perform “awake” intubation (ATI), which is accomplished using either a flexible intubation scope or (more recently), a video laryngoscope. In rougher environments, even the old-fashioned direct laryngoscope may do the trick, but with a much higher discomfort for the patient.

All this is based on a fictional presumption that we have the slightest idea how to identify which one among all the patients is difficult to ventilate or intubate.

Literature [1] [2] [3] [4] has repeatedly shown that the clinical evaluation of predictors for both difficult intubation and mask ventilation is NOT reliable, and yet we keep believing in our fictional ability to predict in which patient we are going to face difficulties. With all that said, I conclude that it is too preposterous of us to guide our conduct based on something that resembles “guessing”. How many of the predictors of difficult ventilation (or which ones in particular) do I need to decide whether to intubate someone before or after induction? For now, we do not know the answer to this question.

There are two different approaches to deal with the aspiration risk. The most common answer is to proceed with the so-called Rapid Sequence Intubation (RSI). The second choice is to intubate first and induce later (ATI – awake tracheal intubation).  The decision between RSI and ATI will be based on the perceived difficulty you could find in intubation. If you suspect that the intubation could be difficult you are compelled to choose ATI, for the sake of patient safety; if there is no reason to suspect that the intubation is difficult you are allowed to proceed with the so-called RSI. Up to this point in the text, there is no polemic question. The worst possible scenario is to have a difficult intubation patient apneic and unconscious, with a tangible aspiration risk with low and falling saturation. If you are uncomfortable with the fact that such an important decision is made based on a very fallible (unreliable) evaluation, it gets worse!

Traditional practice advocates that no mask ventilation should be performed in patients who are not fastened (aspiration risk), due to the presumed risk of gastric insufflation and facilitated regurgitation. Take into consideration that the rationale for RSI is that a paralysed patient with the head elevated to a level superior to the stomach is not able to either vomit or regurgitate, so this paralyzed patient is “safe” from the aspiration risk. Supposing that this rationale is true, this patient could be saved from the aspiration only to “safely die” from hypoxia in the case the anesthesiologist is not able to intubate. The key factor in the safety of RSI is fast success at the first attempt of intubation!

Let’s go to polemic number 1: If a patient’s life depends on the first attempt success, why try a method that is less reliable for first-pass success (direct laryngoscopy)? If the anaesthesiologist chose RSI there is an implicit commitment to achieve first-pass success. It should be obvious by now, after 20 years of the use of VL, that RSI should only be attempted with video laryngoscopy (VL)! So, optimising the first-pass success chance is mandatory every time RSI is chosen; it includes not only VL but VL with the head well above the stomach level (steep reverse Trendelenburg or at least 30-degree dorsum elevation). It also includes proper operator positioning; if the anaesthesiologist is not tall enough, he/she should perform the VL standing over a step to reach the proper operator positioning (head of the patient just below the xiphoid of the operator). I will deliberately NOT enter the polemic of “to do or not to do” cricoid pressure as an attempt to avoid regurgitation (this would make this text too long), but even if you disagree with me and still believe (not like me) in the Sellick’s manoeuvre and perform cricoid pressure, you certainly agree with me that VL certainly reduces attempts at intubation and enables monitoring of correct placement of cricoid force and its impact on the airway and facilitates adjusting manoeuvres (due to shared vision of the screen between operator and assistant). So, polemic question number 1: – Should we ban DL for good in the RSI scenario?

Keep the first polemic question in mind while I pose you the second (and for me more important) polemic question: Should we really avoid mask ventilation during the lapse of time in which the patient loses consciousness, and try the first intubation attempt? Or in other words, is the NO ventilation a reasonable rule?

I happened to read a recent study[5] that strengthened my belief that the NO ventilation rule is illogic, counterintuitive, a relic from the past, and should be banned. It confirms my practice of gentle mask ventilation during the interval between induction and laryngoscopy. Any oxygen is much better than NO Oxygen, that is why I always add (to gentle manual ventilation), the highest possible oxygen nasal flow while performing laryngoscopy (Levitan’s NODESAT[6] technique) whenever I take the option to perform RSI.

References

1. [1] Nørskov, A. K., Rosenstock, C. V., Wetterslev, J. Anaesthesia, (2015), 70: 272
2. [2] Lundstrøm LH, Rosenstock CV, Wetterslev J. Anaesthesia. 2019 Oct;74(10):1267
3. [3] Roth D, et all. Cochrane Database of Systematic Reviews 2018, Issue 5.
4. [4] Detsky ME, et all/ JAMA. 2019 Feb 5;321(5):493-503.
5. [5] JD Casey. n engl j med 380;9 nejm.org February 28, 2019. 811
6. [6]Scott D. Weingart, Richard M. Levitan, Annals of Emergency Medicine Volume 59,n3 March 2012 :165