Damage Control Principles for the Unstable Airway - Part I: Indications and Preparation
- nicholaschapmannz
- 4 days ago
- 8 min read
Updated: 21 hours ago
Rapid sequence induction (RSI) is the most widely used type of induction when securing the airway in trauma. Its original core principles - rapid induction, neuromuscular blockade, cricoid pressure, and immediate intubation without mask ventilation - were all designed to reduce aspiration risk [1].
"Damage control surgery" is largely underpinned by the following three principles - minimising the time the patient spends in a physiologically vulnerable state (i.e., under a general anaesthetic on a cold operating table), focusing on the stabilisation of the physiological derangement (i.e., rather than the definitive repair of anatomical defects), and minimising contamination [2].
In trauma, induction and intubation pose a unique challenge due to the combined effects of hypovolemia, a full stomach, the potential for cervical spine injury, and the need to juggle other time-critical components of resuscitation. In this context, RSI should be reframed as damage control airway management - an approach where the choice of timing, drugs, and technique is tailored to achieve speed, stabilise physiology, and minimise contamination.
This isn't designed to teach you how to assess a difficult airway, or troubleshoot a failed airway, or actually even how to intubate at all. This review is designed to outline the aspects of anaesthetic induction and endotracheal intubation that are specific to trauma, and emphasise these damage control principles.
Indications
There is a very specific question the surgeon must answer during damage control surgery:
Does this *need* to be done right now, or can it wait until the patient is in a better state?
The trauma surgeon is not fiddling with anastomosing the small bowel, they are busy with the control of haemorrhage and contamination - those two things, only, and in that order. The anastomosis can wait until the patient is stable and be later done as a staged procedure.
The same question should run through every clinician's head when making the decision to intubate the unstable trauma patient. Is this necessary right now? Should we be resuscitating more before we intubate? Or should it wait until the surgeon is standing beside the patient, scalpel in hand, ready to put knife to skin? Prioritise the stabilisation of the physiology that's deranged above the anatomical placement of a prosthetic airway [3], unless that airway is urgently needed for the stabilisation of the specific physiology that's deranged.
Different clinicians will have different thresholds for intubation. This will largely be based on where their risk tolerance sits, their level of comfort managing an airway, the broader clinical circumstances, and the overall departmental context - and how all of those things overlap. So, rather than present a strict series of rules - let's instead consider a series of reasonable clinical scenarios within which most trauma patients who need intubation will fall:
1) The airway is not patent - for example, consider the patient with airway burns or laryngeal trauma who is sitting bolt upright or has stridor, or the patient with a head injury who is snoring despite adequate positioning or basic airway adjuncts. The passage of air through their airway is impeded, and some plastic is needed to create a passage.
2) The airway is not protected - consider the seizing or head injured patient whose level of consciousness is sufficiently depressed to impair their management of secretions or vomit. This is not technically defined as the presence or absence of a gag reflex, as this is absent in 37-66% of normal young adults [4,5] (and note that there is no evidence that its presence or absence corresponds to other protective reflexes or predicts a need for intubation). In head injury the traditional threshold is considered to be a GCS ≤8 - but there's nuance here - the need for intubation will depend on trajectory and the aspiration risk - this will be higher in patients who are obese, pregnant, or actively vomiting, and lower in other patients. There is always a judgement call to be made.
3) There is a failure of oxygenation or ventilation - if hypoxia is not responding to maximal O2 supplementation, then intubation can be required as a means of access to PEEP and an FiO2 higher than what can be delivered non-invasively. If hypercapnia is worsening - for example in a patient who is drowsy or has chest injuries, then mechanical ventilation may be required as a means of access to an adequate respiratory rate and/or tidal volume. Given that we do not use NIV in the TEU Resuscitation Room - this won't be covered here as an alternative.
4) The anticipated clinical course includes unacceptable risk - if there is a high likelihood of airway deterioration, then intubation may be considered early before the indications above arise - and the threshold for this "likeliness" may be lower the worse the consequences of deterioration would be. This can come in many forms. Consider the patient with intra-oral burns, carbonaceous secretions, and singed nasal hair, or the patient with an expanding neck haematoma, neither have any stridor or hypoxia yet - but there may be an unacceptable likelihood that oedema or haematoma later causes them to, and intubating them at that point will be far more difficult as a result. Also consider the hypoxic patient - if they are likely to deteriorate further, it might be better to intubate earlier when pre-oxygenation will be easier and therefore RSI can occur under conditions of relative stability.
5) There is a need for situational control - consider the combative patient who does not have capacity to make medical decisions. Agitation may be due to hypoxia, cerebral hypoperfusion, head injury, the effects of alcohol or other drugs, or the patient may be post-ictal - or a combination of any or all of them! For the safety of the patient, the safety of staff, and the ability to effectively undertake assessment and treatment - especially CT imaging - it can be necessary to intubate these patients.
6) Anaesthesia is necessary for humanitarian reasons - consider the patient with large percentage burns or extensive orthopaedic injuries. The analgesic and sedative requirement may be such that intubation is necessary, irrespective of how their airway is currently.
Each of these patients have different considerations for preparation, urgency, and risk. But whatever the reason - does it need to happen now?
Image courtesy of the ATLS course manual, 10th Ed [6].
The process
Trauma RSI must balance speed with safety. The classic '7P’s' of RSI show the structure of the process in time order. Here we will deal with the first three, with the following four dealt with in Part II of this article.
Preparation - a checklist mentality is essential - most hospitals have a formal intubation checklist, the TEU currently does not. Consider the following '5S's' as a framework for you to perform your own checklist for preparation:
Think about your space - are we in the right place for this? Can we move from where we are to a Resuscitation Bay? Does this even need to happen in the Resuscitation Room, or should it be done in theatre?
Think about your self - Am I ready? Have I been to the bathroom? Am I in the right headspace? Should I be letting someone more experienced do this procedure? Do I have my PPE?
Think about the sickie - How can we best resuscitate before we intubate? What physiology can we optimise? How can we best pre-oxygenate the patient? How can we best position the patient?
Think about the staff - Have we allocated roles? Do we all share the same mental model for our airway plan and the anticipated risks? Does someone need to be scrubbed for a surgical airway just in case?
Think about the stuff - Do we have all the right monitoring? Is it working? Do we have suction? Is that working? Have we chosen and checked our induction drugs? Do we have rescue equipment? Do we have rescue drugs drawn up?
Pre-oxygenation - providing an FiO2 of 100% for 3 minutes replaces the nitrogen in the mixed alveolar gas content of the lung’s functional residual capacity with oxygen to maximise apnoeic time and avoid the need for mask ventilation that would risk gastric insufflation and vomiting. Apnoea time can be prolonged in critically hypoxic or obese patients by oxygenating them sitting up and only positioning them right before intubating. Continuing 15L/min O2 via nasal cannulae during the attempt at intubation will also extend the duration of time before desaturation to 95% occurs from 3.5 to 5.3 minutes. This “apnoeic oxygenation” takes advantage of aventilatory mass flow – even though paralysed, the patient's circulation is unaltered, and so the constant diffusion of alveolar oxygen into capillaries creates a downward concentration gradient from the upper airways to the gas-exchanging portions of the lungs.
Pre-treatment - traditionally it was taught that this should be given "3 minutes" prior to induction. But in reality, different "pre-treatments" will need to occur at different times. Do you consider resuscitation as part of your "pre-treatment"? Consider which patient groups (based on pathology, age, or pre-intubation vital signs) might benefit from things like volume replacement, atropine, adrenaline, metaraminol, lignocaine, or short-acting opioids to offset the specific deleterious physiological effects of induction that may affect them. These effects include, but are not limited to:
Bradycardia due to hypoxia or the effect of airway manipulation on vagal tone.
Hypotension due to the direct cardiodepressant effects of some induction agents (e.g. propofol).
Hypotension due to the vasoplegic effect of suddenly losing the painful and scary stimulus that was keeping your sympathetic tone active (this is why ketamine can still result in hypotension).
Hypotension due to the effect of PEEP on venous return and therefore stroke volume / cardiac output.
Acidosis due to the sudden loss of respiratory compensation during the apnoeic period.
Raised ICP due to the stimulating effect of airway manipulation or the effect of positive pressure ventilation impairing venous drainage from the head and neck.
You'll notice that hypotension features three times - and with good reason. The process of intubating a patient and subsequently ventilating them contributes to hypotension is a myriad of ways, and our strategies for combating it will therefore depend on the relative contribution of each. In the unstable trauma patient, the largest contributor to shock is most likely hypovolaemia, with tachycardia and vasoconstriction occurring as part of our body's efforts to compensate using our sympathetic tone. Given this, volume resuscitation is likely to be the most important pre-treatment, along with push-dose adrenaline in an effort to offset the loss of sympathetic tone that will occur when we remove the awareness of pain. A key part of maintaining stability is also the dose reduction of our induction agent - we will cover this in Part II, along with the remainder of our 7P's.
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] Brown CA, Sakles JC. Rapid sequence intubation in adults for emergency medicine and critical care [Internet]. UpToDate. 2025 [cited 7 Nov 2025]. Available from: https://www.uptodate.com/contents/rapid-sequence-intubation-in-adults-for-emergency-medicine-and-critical-care Lamb CM, MacGoey P, Navarro AP, Brooks AJ. Damage control surgery in the era of damage control resuscitation. Br J Anaesth. 2014;113(2):242-9.
[2] Lamb CM, MacGoey P, Navarro AP, Brooks AJ. Damage control surgery in the era of damage control resuscitation. Br J Anaesth. 2014;113(2):242-9.
[3] Ferrada P, Shafique S, Brenner M, et al. Prioritizing circulation over airway to improve survival in trauma patients with exsanguinating injuries: a world society of emergency surgery-panamerican trauma consensus statement. World J Emerg Surg. 2025;20(1):47.
[4] Davies AE, Kidd D, Stone SP, MacMahon K. Pharyngeal sensation and gag reflex in healthy subjects. Lancet. 2995;345)8948):487-8.
[5] Lim KS, Hew YC, Lau HK, Lim TS, Tan CT. Bulbar signs in normal population. Can J Neurol Sci. 2009;36(1):60-4.
[6] American College of Surgeons Committee on Trauma. ATLS Advanced Trauma Life Support® Student Course Manual. 10th ed. Chicago, IL: American College of Surgeons; 2018.
