EMCrit Podcast 40 – Delayed Sequence Intubation (DSI)

Update: Want more on DSI after you listen to the podcast below. My friend Minh Le Cong interviewed me on DSI on his amazing PHARM Podcast. It is an additional 45 minutes on newest thoughts on DSI.

Here is the reference for the incredible guidelines on ketamine in the ED.

On to Delayed Sequence Intubation (DSI)

The Case

You have a 50 y/o male with bad bilateral pneumonia. BP 108/70, HR 96, RR 28. He is delirious, agitated, and looks sick, sick, sick! Saturation is 70% on a nasal cannula; when you try to place the patient on a non-rebreather (NRB) he just swats your hand away and rips off the mask. It is obvious to everyone in the room that this patient needs intubation, but the question is how are you going to do it?

Your first impulse may be to perform RSI, maybe with some bagging during the paralysis period. This is essentially a gamble. If you have first pass success, you (and your patient) may just luck out, allowing you to get the tube in and start ventilation before critical desaturation and the resultant hemodynamic instability. However, the odds are against you: bagging during RSI predisposes to aspiration, conventional BVM without a PEEP valve is unlikely to raise the saturation in this shunted patient, and if there is any difficulty in first-pass tube placement your patient will be in a very bad place.

A Better Way

Sometimes patients like this one, who desperately require preoxygenation will impede its provision. Hypoxia and hypercapnia can lead to delirium, causing these patients to rip off their NRB or non-invasive ventilation (NIV) masks. This delirium, combined with the low oxygen desaturation on the monitor, often leads to precipitous attempts at intubation without adequate preoxygenation.

Standard RSI consists of the simultaneous administration of a sedative and a paralytic agent and the provision of no ventilations until after endotracheal intubation (1). This sequence can be broken to allow for adequate preoxygenation without risking gastric insufflation or aspiration; we call this method “delayed sequence intubation” (DSI). DSI consists of the administration of specific sedative agents, which do not blunt spontaneous ventilations or airway reflexes; followed by a period of preoxygenation before the administration of a paralytic agent.(2)

Another way to think about DSI is as a procedural sedation, the procedure in this case being effective preoxygenation. After the completion of this procedure, the patient can be paralyzed and intubated. Just like in a procedural sedation, we want our patients to be calm, but still spontaneously breathing and protecting their airway.

The ideal agent for this use is ketamine. This medication will not blunt patient respirations or airway reflexes and provides a dissociative state, allowing the application of preoxygenation. A dose of 1–2 mg/kg by slow intravenous push will produce a calmed patient within ~ 30 seconds. Preoxygenation can then proceed in a safe controlled fashion. This can be accomplished with a NRB, or preferably in a patient exhibiting shunt, by use of a non-invasive mask hooked up to ventilator with a CPAP setting of 5-15 cm H20 (or some of the new masks that don’t require a machine, but more on that soon). After a saturation of > 95% is achieved, the patient is allowed to breathe the high fiO2 oxygen for an additional 2–3 min to achieve adequate denitrogenation. A paralytic is then administered and after the 45–60 second apneic period, the patient can be intubated.

In patients with high blood pressure or tachycardia, the sympathomimetic effects of ketamine may be undesirable. While, these effects can be blunted with small doses of benzodiazepine and perhaps, labetalol (3), a preferable sedation agent is available for these hypertensive or tachycardic patients. Dexmedetomidine is an alpha-2 agonist, which provides sedation with no blunting of respiratory drive or airway reflexes (4-5). A dose of 1 mcg/kg administered over 10 minutes will lead to a sedated patient who will accept preoxygenation after 3-5 minutes in most cases.

Another advantage of DSI is that frequently, after the sedative agent is administered and the patient is placed on non-invasive ventilation, the respiratory parameters improve so dramatically that intubation can be avoided. In these cases, we then allow the sedative to wear off and reassess the patient’s mental status and work of breathing. If we deem that intubation is still necessary at this point, we can proceed with standard RSI by administering a conventional sedation agent (e.g. etomidate or additional ketamine) in combination with a paralytic, as the patient has already been appropriately preoxygenated.

A video demonstrating the above concepts is at: http://emcrit.org/misc/preox/

A version of this article originally appeared in ACEP News.
1. Walls RM, Murphy MF. Manual of emergency airway management, 3rd edn. Philadelphia, PA: Lippincott Williams & Wilkins; 2008.
2. Weingart SD. Preoxygenation, reoxygenation, and delayed sequence intubation in the emergency department. J Emerg Med2010 Apr 7. [Epub ahead of print]
3. Aroni F, Iacovidou N, Dontas I, Pourzitaki C, Xanthos T. Pharmacological aspects and potential new clinical applications of ketamine: reevaluation of an old drug. J Clin Pharmacol 2009;49:957–64.
4. Carollo DS, Nossaman BD, Ramadhyani U. Dexmedetomidine: a review of clinical applications. Curr Opin Anaesthesiol 2008;21:457–61.
5. Abdelmalak B, Makary L, Hoban J, Doyle DJ. Dexmedetomidine as sole sedative for awake intubation in management of the critical airway. J Clin Anesth 2007;19:370–3.
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Comments

  1. Sebastian says:

    Nice article !! I only suggest to include a note saying that ketamine should be avoided in agitation do to TBI or stroke, because it enhance oxygen consumption in the brain and increase damage.
    Greetings !!

    • I’d suggest you read this piece…
      Myth: Ketamine should not be used as an induction
      agent for intubation in patients with head injury
      Yevgeny Filanovsky, MD;* Philip Miller, MD;† Jesse Kao, MD‡
      CJEM 2010;12(2):154-7

      Here is the conclusion:
      Based on its pharmacological properties, ketamine
      appears to be the perfect agent for the induction of
      head-injured patients for intubation. The evidence for
      neuroprotection in humans remains inconclusive at
      this time. However, more recent prospective data
      examining ketamine usage as a sedative agent in
      patients treated with mechanical ventilation suggests
      that there is no association with increased ICP in head
      injury.
      Despite limited evidence specific to its use as an
      induction agent, we feel that additional consideration
      must be paid to the possible usage of ketamine for RSI
      in patients with head injury, especially when alternative
      agents that do not cause hypotension are unavailable.

  2. Matt L. Wong says:

    Great ideas and a great article. I love your work.

    However, check the URL in the JEM article you provide for the video demonstration. Should it still be “blog.emcrit.org/misc/preox” or simply “emcrit.org/misc/preox”? I can’t access the former.

  3. Erin Schneider says:

    What do you suggest for the hypertensive tachycardic patient if you do not have dex available?

    • a small dosage of propofol would do nicely

      • Folks,

        this could be made to work with many sedative agents, but I can’t recommend any of them, b/c the potential to screw-up is much higher. It doesn’t mean you could not do this with propofol, etomidate, or versed; it just means it is tougher and riskier. The other problem is that the sedative dose for the preox will not be the same as the induction dose for the intubation with these other agents.

  4. Scott Gallagher says:

    I like your approach with Ketamine. I think that it is conceptually similar to the rapid sequence airway (RSA) approach advocated on the UNM airway site as a bridge to intubation(http://hsc.unm.edu/emermed/Airway911/Videos/RSA_Preoxygenation.html).

    However, the RSA technique differs in that they take away protective reflexes in order to place an NG-loaded LMA Supreme to facilitate preoxygenation prior to ETT attempt of a suspected difficult airway.

    Interesting small case series using Precedex for awake, difficult intubation:
    Dexmedetomidine as sole sedative for awake intubation in management of the critical airway. Abdelmalak B – J Clin Anesth – 01-AUG-2007; 19(5): 370-3

    • Darren Braude’s RSA technique is another great way to go and I have used it a bunch. Great dexmedetomidine reference, Scott.

    • my concern about RSA is that you are paralyzing a patient who is not optimally preoxygenated — the margin for something going wrong is pretty tight!

  5. David Marr says:

    What about pain management with the DSi sequence. At what point would you give your first dose of Fentanyl, and would you use the same dose as with a true RSI like 3mcg/kg?

    • Ketamine is a potent analgesic, no additional pain control should be necessary. If you are using demedetomidine, I sometimes will add a little fentanyl.

  6. looking forward to giving this a whirl on my next appropriate patient.
    am limited by not having dex at my shop (or droperidol. hahaha)

  7. Great work as always Scott – waiting for the next blue, agitated patient to come in. For those of us without easy access to droperidol – is there much difference between droperidol and haloperidol in practice?

    • my experience, and i think the literature bears this out, is that haldol is slower and less sedating. you might not get them compliant enough with the haldol to stave off the crash tube.

      s

  8. Scott: Can you comment on the use of Ketamine and DSI in the Excited Delirium patient (specifically PCP, Cocaine, Bath Salt toxicity). Handcuffed, profusely diaphoretic, tachycardic, highly agitated and uncooperative. Thanks.

    • Minh’s blog, PHARM is the best source for info on that exact question.

      • Thanks. I used Midazolam IM, got patient transferred to bed, NRB mask, IV access, RSI with Propofol/Roc. Went pretty smooth but no DSI. I am sure guy was hypoxic, not sure if hyper or hypo-carbic.

  9. Javier Benitez says:

    Happy 4th

    I’m going through the literature of DSI now. My patient is agitated, acidotic, tachypneic, and hypoxic is DSI ideal for this patient?

    Thanks in advance

    Javier

  10. Josh Farkas says:

    Scott,

    Brilliant podcast, thanks.

    I am especially interested in the subset of patients who get ketamine or precedex and then improve and don’t require intubation. There seem to be a subset of patients with asthma or COPD who get into a vicious spiral of (anxiety ==> hyperventilation ==> autoPEEP & gas trapping ==> ineffective ventilation ==> anxiety, etc). I’ve had a lot of success with precedex gtt + BiPAP in this situation to help them slow down their respiratory rate enough to ventilate effectively (and avoid intubation). It needs to be done on carefully selected patients with extreme vigilance but so far I’ve gotten lucky. Any thoughts on this?

    Josh

    • Those are exactly the pts that avoid intubation. Dexmedetomidine works nicely for DSI as well. The advantage of ketamine is its intrinsic bronchodilation.

      • Scott/Minh or anyone else,

        You ever had a really hypoxic, precarious patient such as the one described by Josh Farkas who also had a particularly difficult looking airway? Did you ever in those cases think about trying video laryngoscopy with the ketamine on board while the patient is breathing thereby avoiding the paralyctic altogether? Gentle peak with the glidescope for example?

  11. MichaelMD says:

    I had a patient the other night come in with flash pulmonary edema, but also febrile from a nursing home. Wasn’t sure if it was his CHF or ARDS, but he looked awful. Despite CPAP of 5 by prehospital care, his sat on arrival was 89%.

    Now in the past, prior to following your practice suggestions, I would have just tubed him then and there. Just said screw it, CPAP isn’t working, he’s still hypoxic and tachypneic and barely responsive.

    But I didn’t because I’m smarter than that thanks to your podcast! I put him on BIPAP instead, bumped his expiratory pressure up a bit, got his sat about 96%, left him there for a few minutes, then did passive oxygenation by nasal cannula. It took the resident about 45 seconds to get the tube, but the patient never desat’d below 95%. It would have been a really different story had we started with a pulse ox of 89%. What could have been a crash airway disaster went as smooth of an RSI as you could get.

    I didn’t have to use ketamine, so technically not DSI, but the concepts the same, using NIV positive pressure ventilation to preoxygenation.

    Thanks again for all you do!

  12. Hi Scott – thanks for all your work with the website very useful stuff. Recently I used DSI to successfully intubate a non resolving post-ictal patient (sidenote – I am a critical care flight Paramedic not a Physician). Worked great in a patient that was trending towards the airway death spiral 500+ statute miles from the closest hospital.

  13. Scott Gallagher says:

    Scott,
    I love the DSI concept. However, because there is very little negative discussion of the concept I would like to share that I had a case recently in a child.

    I administered Ketamine to a 2 year child with bleeding profusely after eschar sloughed from T&A procedure. Child had borderline sats and was placed on nasal cannula oxygen, NRB and administered Ketamine. Shortly after Ketamine administration patient vomited copious amounts of swallowed blood obscuring the airway and making for a difficult intubation

    Is there some inherent risk in the ‘delay’ portion of DSI of losing the airway to stomach contents? Is the RSI concept not based upon this risk of vomiting during airway manipulation?

    • not in adults, which is the only area I have ever advocated DSI. Adults have never had a case of periprocedural vomiting in the literature from ketamine. Kids definitely have.

      RSI is based on no positive pressure ventilation to avoid vomiting. DSI also avoids this. Kids can definitely vomit from ketamine during the procedure. While there has one been one case of Peds DSI in the literature, I do not treat children and can’t advocate the practice in a cohort I know very little about. Thanks for sharing the case.

  14. Ali Eskandar says:

    Thank you scott for your lecture I learned alot !!!
    I need to ask you did you have the chance to publish your case series ?
    I would like to bring DSI topic to ecommunity chest network for further discussion if possible ….

Trackbacks

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