Damage Control Principles for the Unstable Airway - Part II: Induction & Intubation
- Nov 28, 2025
- 8 min read
Updated: Dec 15, 2025
In Part I of this series we discussed the indications for intubation in trauma, and what analogies can be made to damage control surgery. Primarily, this involves determining whether intubation really needs to occur right now (or whether it would be better to delay until in a place of safety), a focus on the stabilisation of physiology, and a focus on preventing contamination.
The process
We have been using the classic '7P’s' of RSI to show the structure of the process in time order. We have already covered the first three in Part I, which are then followed by:
Paralysis with induction - in the TEU, we most commonly use the combination of ketamine and rocuronium. This is a common combo, and so we will focus on these two. Let's first discuss the dose, then we can move on to the sequence.
First and foremost, the doses - the induction doses for these drugs are typically 1-2mg/kg IBW (for ketamine) and 1.2mg/kg IBW (for rocuronium) [1,2]. There's room to move on both of these fronts, however.
Ketamine - In the unstable patient, there are two things to consider. First, in the truly peri-arrest patient, the amount of compensatory vasoconstriction is likely to mean that each molecule of ketamine is only being pumped in one tiny loop between the heart, lungs, and brain - and is likely bypassing the gut, kidneys, skin, and limbs entirely. A more significant anaesthetic effect is therefore likely at a lower dose because there's no perfusion of these other compartments (and also less intercompartmental clearance as a result) [3]. Second, while ketamine does have a sympathetomimetic effect; a shocked patient is reliant on their sympathetic tone to compensate for hypovolaemia and maintain their blood pressure. The loss of the awareness and painful stimulus that occurs with anaesthesia will more than offset this sympathomimetic effect, and this will have more significant haemodynamic effects than in a patient who is volume replete. A dose reduction is therefore likely to be necessary. There is significant concern (fairly so) about the rates of awareness following intubation in emergency settings - but in this sub-group of profoundly unstable trauma patients, keeping the patient alive takes precedence over everything else. See the "hierarchy of airway needs" diagram below [4]:
If they're going to be aware of it, at least let them have no memory of it, and if they are going to remember it, at least let it not be painful, and if they do remember it being painful, at least let them remain stable and, if not that, then at least alive. Ultimately that's what your patient's mum, wife, husband, brother, sister, or child will care about - as will the coroner. Most guidelines seem to stop short of recommending any dose reduction below 0.5mg/kg in the unstable patient [5], but dosing is a sliding scale, and this will likely vary depending on A) the patient's level of consciousness pre-induction and B) degree of instability. A patient with no consciousness and no pulse will get no induction dose, after all.
Rocuronium - ultimately we want to achieve the best intubating conditions we can, as fast as we can. There's some evidence that increasing the dose to 2mg/kg may improve timely first-pass success. In a small study (n=60) [6], the proportion of patients with an "excellent" view of the cords (black) at 40 seconds was greater with higher doses than it was for lower doses, who correspondingly had greater proportions of patients with "good" (white) or "poor" (grey) views:
And the time-to-optimal-conditions duration does matter. If we think back to the damage control principles discussed in Part I - one of the core concepts mentioned was minimising the time the patient spent in a state of vulnerability (that cold operating table, under a general anaesthetic, losing heat through their open belly). Likewise, during RSI, we want to minimise the period of time the patient spends in this window of vulnerability - the period from giving the induction dose to the moment we have a cuffed tube inflated below the cords. Part of this is how long it takes us to actually intubate, but part is what's known as the sedation lag time. This is the window between the onset of sedation and the paralytic taking effect where intubation can't yet start. During this time, de-recruitment is occurring, hypercapnia is developing, and aspiration risk is at its highest. Sometimes a "delayed sequence induction" is necessary - where sedation is required for behavioural control to allow optimisation of physiology to occur - but in an ideal world, rapid sequence induction is optimal, so that this sedation lag time can be minimised. The PulmCrit article here sums it up well [7]:
As for the sequence, there's really only two options; ketamine first, or rocuronium first. There are pros and cons for each:
"Keturonium" - this is the traditional sequence, ketamine first, then rocuronium.
"Rocketamine" - this is the reverse sequence, advocated for by some clinicians.
Giving the rocuronium prior to the ketamine means that the sedation lag time can be minimised, and the window of vulnerability therefore made narrower. There is some theoretical benefit to this, as it mitigates the complications of a prolonged sedation lag time mentioned above. Given a mean time of onset of 10-30 seconds for ketamine [8] and 45-60 seconds for rocuronium [9] (and assuming it takes 5 seconds to swap out the syringe and give a flush), this would mean that giving these in a "keturonium" sequence causes a sedation lag time of 20-55 seconds, and for a "rocketamine" sequence a sedation lag time of 10-45 seconds.
These "time of onset" numbers shouldn't be taken as gospel, as they will vary with differing doses and how sluggish a patient's circulation is. But using them as a rough estimate, the "rocketamine" sequence should theoretically reduce the sedation lag time by about 10 seconds. But does this hold up in reality? Well, studies have indeed shown that time to intubation is reduced by about 6 seconds [10]. The other argument made for using the "rocketamine" sequence is that with the "keturonium" sequence there is a risk that the patient will be apnoeic following the onset of the ketamine, but prior to the onset of the rocuronium, causing the airway operator to attempt laryngoscopy while thinking, in error, that the patient is paralysed, and stimulating them to vomit into their yet-unprotected airway. The risk with "rocketamine", however, is that you lose your IV access after giving the rocuronium, and force the patient to remain paralysed but aware, while you valiantly bag-mask ventilate them, insufflating their stomach anyway, patiently awaiting the establishment of more IV access. But, this is ultimately why we have redundancy, and obtain more than one site of IV access. Unfortunately the study cited above did not look at rates of awareness. It may be something to consider in the obese, pregnant, critically hypoxic, or critically acidotic patient, where the safe apnoea time is shorter, and the speed of intubation is paramount.
Whichever way you give it, once the flush that drives in the paralytic is pushed, the clock is started. Slow gentle BVM ventilation at 6-8/min can occur in this phase if it is crucial to avoid hypercapnia but otherwise this should be avoided.
Positioning with protection - if there is no concern regarding the patient's cervical spine, “ramp” the patient head up so that the external auditory canal is parallel with the sternal notch. This will help bring the glottis more posterior. Realistically, positioning can be done at any point, but if the patient has moved, this is your last chance to get it right. If there is concern regarding the potential for cervical spine injury, any collar should come off and manual in-line axial stabilisation should occur. This will mean the airway is relatively anterior, and therefore a hyperangulated blade with a stylet may be your friend.
Placement with proof - after 45-60 seconds, once unconscious and relaxed (which can be assessed by wiggling the mandible to assess muscle tone, observing for apnoea (or witnessing fasciculations to have ceased, if using suxamethonium), then intubation can occur.
This is the easy bit. You know how to do this bit.
The application of cricoid pressure remains controversial. The bulk of the evidence suggests it yields no change in the rate of aspiration, while significantly reducing the grade of view obtained and the rate of first pass success [11]. However, everyone has an anecdote about removing the cricoid pressure and immediately seeing gastric fluid bubbling up from the oesophagus. One could make the argument that it's easy enough to remove if it's proving unhelpful, but one could also make the argument that time is of the essence - and the argument for minimising the need for additional communication and complexity is a valid one.
Post-intubation management - endotracheal intubation is then verified by the three sisters of success - Tracy, Misty, and Chesty. Once you've confirmed placement with your ETCO2 trace, the misting of the tube, and the presence of bilateral chest movement and air entry, secure the tube and connect them to the ventilator.
Take Home Points
Rapid sequence induction in trauma can be necessary for a wide variety of reasons in a wide variety of different patient groups. The burned airway will be very different to the head injured airway, which will in turn be very different to the hypoxic airway, or the combative shocked peri-arrest airway. Each have their own optimal timeframes, considerations, and risks - but whenever there is an "unstable" patient requiring intubation - whether this is due to critical hypoxia, acidosis, or shock - re-framing this as the "damage control airway" can help crystallise the priorities in that moment, just as it has done for damage control surgery.
As is the case for the small bowel anastomosis that needn't occur during the index laparotomy: consider whether this procedure even needs to happen right now or can it wait and be done at a safer time? How can you optimise the patient's physiology prior to performing this procedure? And how can you minimise the window of vulnerability we are exposing the patient to during this procedure?
Dr Dimitris Zafeiriadis is a Greek anaesthetist with a special interest in trauma management and solid-organ transplantation, and is currently undertaking further sub-specialty training in critical care medicine. He is actively involved in medical education as an instructor on multiple courses, and is engaged in doctoral research in the field of liver transplantation.
Dr Nick Chapman is a senior emergency medicine registrar, and has recently passed his written fellowship exams for the Australasian College of Emergency Medicine. He has a strong interest in both trauma and retrieval medicine, and completed his Postgraduate Diploma in Aeromedical Retrieval in 2021. He has previously worked at The Alfred Hospital's Emergency & Trauma Centre, but is hanging up his scrubs in favour of overalls as he heads to the Royal Flying Doctor Service.
References:
[1] Morris C, Perris A, Klein J, Mahoney P. Anesthesia in haemodynamically compromised emergency patients: does ketamine represent the best choice of induction agent? Anaesthesia. 2009;64(5):532-9.
[2] Life in the Fast Lane. Rapid sequence intubation [Internet]. 2024 [cited 7 Nov 2025]. Available from: https://litfl.com/rapid-sequence-intubation-rsi/
[3] Egan ED, Johnson KB. The influence of hemorrhagic shock on the disposition and effects of intravenous anesthetics: a narrative review. Anesth Analg. 2020;130(5):1320-30.
[4] EMCrit. Laryngoscope as a Murder Weapon (LAMW) series - hemodynamic kills [Internet]. 2013 [cited 6 Nov 2025]. Available from: https://emcrit.org/emcrit/intubation-patient-shock/
[5] Life in the Fast Lane. Intubation, hypotension and shock [Internet]. 2024 [cited 7 Nov 2025]. Available from: https://litfl.com/intubation-hypotension-and-shock/
[6] Heier T, Caldwell JE. Rapid tracheal intubation with large-dose rocuronium: a probability-based approach. Anesth Analg. 2000;90(1):175-9.
[7] EMCrit. PulmCrit - Rocketamine vs. keturonium for rapid sequence intubation [Internet]. 2017 [cited 7 Nov 2025]. Available from: https://emcrit.org/pulmcrit/pulmcrit-rocketamine-vs-keturonium-rapid-sequence-intubation/
[8] Rosenbaum SB, Gupta V, Patel P, et al. Ketamine [Updated 30 Jan 2024]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470357/
[9] Jain A, Wermuth HR, Dua A, et al. Rocuronium [Updated 28 Feb 2024]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539888/
[10] Driver BE, Klein LR, Prekker ME, et al. Drug order in rapid sequence intubation. Acad Emerg Med. 2019;26(9):1014-21.
[11] White L, Thang C, Hodsdon A, Melhuish T, Vlok R. Cricoid pressure during intubation: a systematic review and meta-analysis of randomised controlled trials. Heart Lung. 2020;49(2):175-80.
