Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

Delayed Sequence Intubation (DSI)

There is a fascinating podcast, although it is not really relevant to EMS in the US, yet. It feels as if this is something that will be part of EMS in the future. EMCrit Podcast 40 – Delayed Sequence Intubation (DSI). There is also a short video (less than 5 minutes) covering DSI and a couple of other airway/preoxygenation topics.

I know. I am a research guy, so why am I going on feelings?

There is a lot of research out there on ketamine, and much more in the works. All of it appears to be producing positive results as far as efficacy and safety. I would be surprised if there is a discovery of some unknown danger.

It is certainly possible that a problem turns up. There have been cases of apparently safe drugs that have been shown to have significant dangers after being used for a while. However, outside the US, ketamine has been used extensively. How extensively? Even EMS uses ketamine. We appear to be way behind the times in doing what is best for patients. Not because it is fashionable. not because others are doing it. Not because it is the cool thing to do. Because it seems to provide a lot of benefits that our current treatments lack.

Ketamine sedates.

Oh no! The hypotension!

Not with ketamine.

Oh no! The respiratory depression!

Not with ketamine.

Oh no! The depressed airway reflexes!

Guess what?

Not with ketamine.

Ketamine is not perfect, but it appears to be a much better drug for dealing with unstable patients in awkward circumstances.

What is more challenging for EMS, than an unstable patient in awkward circumstances?

Where does EMS make a big difference in outcomes? One place is with the unstable patients in awkward circumstances.

In Etomidate in procedural sedation, I wrote about etomidate, which is another drug that is not a cardiac depressant and can be used for sedation under similar circumstances.

When RSI (Rapid Sequence Intubation/Induction) may not be the right thing to do for a variety of reasons, DSI may be the right thing to do. Maybe EMS can use etomidate for these patients, until we finally realize that ketamine is safe and efficacious.

Ketamine does sometimes produce nausea and/or emergence reactions, but in the podcast, Dr. Weingart gives a good reason for not worrying about these with DSI. The nausea only seems to be a problem in a minority of patients and then only on emergence from the dissociative state. These patients would be kept sedated with ketamine for an extended period – at least until after transfer of care in the ED (Emergency Department).

In an earlier podcast on ketamine, Dr. Weingart explained that he thinks that the problem with emergence from ketamine sedation is similar to the problem with bad LSD (Lysergic Acid Diethylamide – LSD, because Acid is Saure in German) trips.

Should the answer be DSI?

I think that this is coming to the more progressive systems, but another way of using sedation with ketamine (or etomidate) may be to use DSA (Delayed Sequence Airway). Why does airway control need to be with intubation?

It doesn’t.

This article presents a case in which an air medical flight crew encountered a potentially difficult airway when a trauma patient deteriorated in-flight. The crew elected to sedate and paralyze the patient and place a laryngeal mask airway without a prior attempt at direct laryngoscopy and endotracheal intubation. The term Rapid Sequence Airway (RSA) is coined for this novel approach. This article describes and supports this concept and provides definitions of alternative and failed airways.

Rapid Sequence Airway (RSA)–a novel approach to prehospital airway management.
Braude D, Richards M.
Prehosp Emerg Care. 2007 Apr-Jun;11(2):250-2.
PMID: 17454819 [PubMed – indexed for MEDLINE]

The sad thing is that this may still be a novel approach to prehospital airway management almost 4 years later.

But there is a YouTube about it, so how novel can RSA be?

The YouTube is from the medical center where Dr. Braude and Dr. Richards work. When others are doing RSA, then RSA may no longer be a novelty.

Does an extraglottic airway mean increased aspiration?

Maybe not. If we work on ways of monitoring the airway, we may not have any greater incidence of aspiration with extraglottic airways than with intubation. If we become comfortable with extraglottic airways, we may even find that we have a lower incidence of aspiration with extraglottic airways.

What about DSA (Delayed Sequence Airway) with CPAP (Continuous Positive Airway Pressure)?

Why not?

But the patient has to be fully alert for CPAP.

Maybe we will be able to write some more flexible protocols for CPAP and EMS. We are still not using CPAP enough to become as familiar with it as we will need to for innovation.

If you have not done so, yet – Go listen to the podcast.



  1. Great points. Another niche where I believe ketamine would be useful is sedation before cardioversion. It’s the only sedative (that I know of) potentially available to EMS that also has analgesic properties, making it perfect for such a painful procedure. In fact, it’s not so much a sedative as a dissociative agent, removing the patient from their environment, without necessarily inducing total anesthesia (although it’s never used where I work, so I haven’t personally seen its various levels in action, but have heard many first-hand accounts from practitioners who use it regularly).
    Although I’ve also seen a lot of literature on its use for procedural sedation in the ED, and know it has become increasingly used in managing trauma patients, I cannot recall encountering anything on its use specifically in cardioversion. Dissociation sounds like just what we want: a patient who is unaware that we are electrocuting him, but capable of maintaining an airway, respiratory drive, and blood pressure. When using a drug like etomidate in such a circumstance, although the patient is sedated, they will still feel pain and mount a catecholamine surge after being shocked; just what we don’t want if their V-Tach was secondary to myocardial injury.

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