One of most advanced methods of airway management in emergency medical services (EMS) is rapid sequence induction (RSI). In EMS, we encounter patients who don’t need intubation, but may need RSI and are poor candidates for this based off their initial presentation.

So how do we handle these patients? Let’s look at a case.

Case Study

You are requested by an advance life support (ALS) transporting ambulance for an intercept for an RSI for an obese male patient with a full beard in respiratory distress that has progressed to extremis. The transporting paramedic caring for the patient advises you that he is unable to keep continuous positive airway pressure (CPAP) or a non-rebreather on the patient and the patient is becoming combative. The patient is becoming more hypoxic the more agitated he becomes.

Related: Basic Airway Management Turned Sideways

The Question

As you receive this patient’s information and approach toward the patient, you know he may need advanced airway management. How will you accomplish this without being able to pre-oxygenate the patient first?

Pre-Oxygenation Challenge

This is where delayed sequence intubation (DSI) has its place. A patient who is hypoxic, hypercarbic, or both can become combative or delirious. This can cause a patient to pull off any oxygen delivery devices or cause a patient to resist any detailed assessment, let alone interventions, by EMS. To appropriately pre-oxygenate a patient, it is required to provide three minutes of high FiO2 or at least eight vital capacity breaths.1 Patients who are obese or have other comorbidities will take longer to pre-oxygenate. Clearly, this cannot be completed on the delirious or combative patient.


We know that optimizing the patient’s level of oxygen and carbon monoxide is paramount. In some cases, to accomplish this, it may be necessary to sedate the patient. The agent of choice for this procedure, which you can be procedural sedation, is Ketamine. Using Ketamine means there is no blunting of the patient’s ventilatory rate and it allows the patient to be in a dissociated state, which allows the application of pre-oxygenation. Ideal dosing for Ketamine is 1-2mg/kg slow IV push, however, consult your local protocol. This will achieve dissociated sedation in about thirty seconds.

Related: An Emergency Guide to Mechanical Ventilation

There is a subset of patient where Ketamine may not be desirable. Patients with tachycardia or hypertension may not benefit from the effects of Ketamine. Typically for EMS providers, there is not another alternative medication so the effects of Ketamine on these patients can be treated with small bolus doses of a Benzodiazepine or a beta blocker.2


Once adequate sedation has been achieved, oxygenation can be provided to the patient. Ideal methods for delivering pre-oxygenation are noninvasive positive-pressure ventilation (NIPPV) or high-flow oxygen. NIPPV is preferred due to its ability to deliver a higher FiO2 and recruit as much lung tissue for gas exchange as possible.

In patients who develop agonal ventilations after sedation a BVM as mentioned above is the first choice as well as the concept of apneic oxygenation – high-flow oxygen through a nasal cannula. This is also useful if you are providing pre-oxygenation with a BVM to achieve as high of an FiO2 as possible. Apneic oxygenation will be discussed more with intubation.

To Tube or Not to Tube?

The controversial question surrounding DSI is the decision to intubate the patient once oxygenation has been accomplished with some sedation. If your patient is adequately oxygenated, ventilating adequately, and maintaining their own airway, the decision to intubate should be made considering the patient’s ability to maintain their own airway, underlying clinical condition, and their anticipated clinical course. Intubation may be the best possible care for the patient. When this is done, using a paralytic, apneic oxygenation should be used to maintain the oxygenation it has taken some work to obtain.3


If you have made the decision to intubate, continue sedation initially with appropriately dose Ketamine for continued induction and then administer an appropriate paralytic, preferably Succinylcholine or Rocuronium. When paralysis is accomplished, passing an endotracheal tube is the gold-standard for airway management. A newer approach on RSI is Rapid Sequence Airway, or RSA, versus Rapid Sequence Induction/Intubation. If the glottic opening cannot be immediately visualized a supraglottic airway (SGA) may be placed. Remember, that any advanced airway must have continuous waveform capnography in place to not only confirm placement, but to titrate ventilations to the best possible therapeutic rate.

Related: Respiratory Syncytial Virus: It’s the Season

Case Conclusion

Once you have intercepted with the ALS crew and the patient, you immediately decide the best course for this patient is DSI. An appropriate dose Ketamine is administered, and the patient is placed on CPAP. The patient almost immediately calms down and can be oxygenated. Based on the patient’s presentation in extremis and associated comorbidities, you elect to intubate the patient. With the patient being obese and having a full beard, the patient is successfully intubated using additional Ketamine, Rocuronium, and ETT placement with a video laryngoscope. Post-intubation management is completed, and the patient is delivered to the hospital with an advanced airway in place and EtCO2 and SpO2 levels in normal limits.


  1. Preoxygenation, reoxygenation, and delayed sequence intubation in the emergency department. Weingart SD. J Emerg Med2010 Apr 7.
  2. Delayed sequence intubation (DSI). EMCrit Project. (2018, September 17). Retrieved December 1, 2021, from
  3. Delayed sequence intubation by intensive care flight paramedics in Victoria, Australia. Taylor & Francis. (n.d.). Retrieved December 1, 2021, from

Jason Haag is the assistant chief of operations for Finger Lakes Ambulance and the owner of Medivation, LLC. He has more than 20 years of fire and EMS experience and management experience in EMS billing. He started as an EMT in 2003 and advanced to the paramedic level in 2006. In 2008, Jason studied at the University of Maryland Baltimore College to obtain a certification in critical care transport. Jason worked as a CCEMT-P since 2008 and has experience transporting critically ill patients utilizing ventilators, IV pumps, advanced pharmacology, and RSI. He was an EMS supervisor from 2010-2018. Jason successfully earned his CIC certification and teaches for many agencies across New York. He also speaks at conferences, hosts classes, and coordinates educational offerings. Jason continues his EMS advocacy through his active involvement with Finger Lakes Regional EMS Council, NY SEMSCO, Wayne County ALS, AHA instructing, NASEMSE and NAEMT. His involvement with Geneva Fire Department, Boy Scouts, Masons, Rotary, and Ducks Unlimited occupy his days after his daily family time with his wife Jami and son Gavin.

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