Delayed sequence intubation (DSI)


Delayed sequence intubation (DSI) is procedural sedation, where the procedure is preoxygenation

  • DSI may be useful in the patient for whom rapid sequence intubation would inevitably result in significant hypoxaemia because they cannot be preoxygenated by other means
  • Ketamine is the ideal DSI induction agent as it preserves airway reflexes and respiratory drive

Also see Preoxygenation and Apnoeic oxygenation


  • Patient who is agitated or is otherwise intolerant of preoxygenation via nasal prongs, non-rebreather mask, bag-valve-mask, and/or non-invasive ventilation
  • Another procedure is required before intubation, but the patient will not tolerate it (e.g. nasogastric tube placement prior to intubation in the setting of GI haemorrhage)


  • identify agitated patient requiring emergency intubation (see indications)
  • position the patient ‘head up’ at 30 degrees (or more), with auditory meatus above the jugular notch
  • administer induction agent, ideally ketamine 1mg/kg IV
    • give as slow IV push over 15-30 seconds to prevent apnoea
    • can give further doses of 0.5mg/kg IV to achieve complete dissociation if required
  • Ensure the patient has a patent airway
  • Place standard nasal cannula at 15 L/min prior to placement of the preoxygenation device
  • Choose preoxygenation device based on the patient’s SpO2:
    • if SpO2 >95% use:
      • bag-valve-mask (BVM) with PEEP valve and a good seal at 15 L/min O2, or
      • non-rebreather (NRB) mask and a good seal at 15 L/min O2 (or more)
    • if SpO2 <95%:
      • BVM with PEEP valve and a good seal
  • preoxygenate for at least 3 minutes
  • administer neuromuscular blocker and wait 45-60 seconds
    • use suxamethonium 1.5mg/kg IV or rocuronium 1.2mg/kg IV
  • intubate patient


Usual complications associated with:

  • non-invasive ventilation
  • intubation
  • medication side-effects

A particular concern is that DSI goes against the tenets of rapid sequence intubation and may increase the risk of aspiration.


Other induction agents

  • other agents have been suggested as the induction agent for DSI, such as dexmedetomidine, remifentanil and droperidol
  • these agents do not have the same constellation of rapidity of onset, preservation of airway reflexes, preservation of respriatory drive and safety profile as ketamine

Neuromuscular blockade

  • Rocuronium at 1.2 mg/kg is the ideal neuromuscular blocker
    • achieves rapid paralysis comparable to suxamethonium for intubating conditions
    • absence of defasciculation decreases oxygen consumption compared to suxamethonium
  • rarely, DSI averts the need for intubation as the patient (e.g. severe asthma) is no longer agitated and oxygenation improves
    • in these cases it is reasonable to avoid administering the neuromuscular blocker — either allow the sedative to wear off or administer further boluses to maintain ongoing oxygenation
    • However, DSI should only be initiated with the intention of proceeding to intubation

KSI (“ketamine sequence intubation”)

  • the term KSI was proposed by Reuben Strayer
  • KSI is similar to DSI, but an important difference
  • KSI involves performing laryngoscopy and intubation as per the DSI procedure but without using neuromuscular blocker
  • This means that the patient continues to breath spontaneously during the entire procedure (traditionally, keeping patients breathing spontaneously is a central tenet of difficult intubation strategies)
  • Lack of neuromuscular blockade may result in suboptimal intubation conditions however


The current evidence for DSI consists of uncontrolled observational data only

  • Weingart et al, 2014
    • prospective observational study
    • convenience sample of 64 patients (two lost to analysis)
    • patients were those requiring emergency intubation who did not tolerate pre-oxygenation with traditional methods, and were not predicted to have a difficult airway
    • DSI was performed using ketamine resulting in significantly improved oxygen saturations prior to intubation: 88.9% vs 98.8% (increase of 8.9%, 95% C.I. 6.4-10.9)
    • two patients with asthma improved sufficiently to avoid intubation all together
    • there were no complications – two well oxygenated patients had minor reductions in their oxygen saturations but they did not receive nasal cannulae for pre/apneic oxygenation

There are also case reports of use in paediatric patients (Miescier et al, 2015; Lollgen et al, 2014; Schneider and Weingart, 2013)


  • Delayed sequence intubation may be a useful technique for preoxygenation when patients do not tolerate other means of preoxygenation and emergency intubation would be otherwise unsafe due to the risk of hypoxaemia
  • DSI should only be performed by experienced clinicians with airway expertise

References and Links


Journal articles and textbooks

  • Gill S, Edmondson C. Re: preoxygenation, reoxygenation, and delayed sequence intubation in the Emergency Department. The Journal of emergency medicine. 44(5):992-3. 2013. [pubmed]
  • Löllgen RM, Webster P, Lei E, Weatherall A. Delayed sequence intubation for management of respiratory failure in a 6-year-old child in a paediatric emergency department. Emerg Med Australas. 2014 Jun;26(3):308-9. PMID: 24712856.
  • Miescier MJ, Bryant RJ, Nelson DS. Delayed sequence intubation with ketamine in 2 critically ill children. The American journal of emergency medicine. 2015. [pubmed]
  • Schneider ED, Weingart SD. A case of delayed sequence intubation in a pediatric patient with respiratory syncytial virus. Ann Emerg Med. 2013 Sep;62(3):278-9. doi: 10.1016/j.annemergmed.2013.03.027. PMID: 23969131.
  • Skupski R, Miller J, Binz S, Lapkus M, Walsh M. Delayed Sequence Intubation: Danger in Delaying Definitive Airway? Annals of Emergency Medicine. 67(1):143-4. 2016. [pubmed]
  • Weingart SD, Trueger NS, Wong N, Scofi J, Singh N, Rudolph SS. Delayed Sequence Intubation: A Prospective Observational Study. Ann Emerg Med. DOI: http://dx.doi.org/10.1016/j.annemergmed.2014.09.025
  • Weingart SD, Trueger S, Wong N, Singh N, Rudolph SS. In reply:. Annals of Emergency Medicine. 67(1):144-145. 2016. [article]
  • Weingart SD. Preoxygenation, reoxygenation, and delayed sequence intubation in the emergency department. J Emerg Med. 2011 Jun;40(6):661-7. Epub 2010 Apr 8. PMID: 20378297. [Free fulltext]
  • Weingart SD, Levitan RM. Preoxygenation and prevention of desaturation during emergency airway management. Ann Emerg Med. 2012 Mar;59(3):165-75.e1. Epub 2011 Nov 3 PMID: 22050948. [Free fulltext]
  • Weingart SD. Re: preoxygenation, reoxygenation, and delayed sequence intubation in the Emergency Department. The Journal of emergency medicine. 44(5):993-4. 2013. [pubmed]

FOAM and web resources

CCC 700 6

Critical Care


Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.

After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.

He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE.  He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.

His one great achievement is being the father of three amazing children.

On Twitter, he is @precordialthump.

| INTENSIVE | RAGE | Resuscitology | SMACC

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