Prehospital Management of Traumatic Brain Injury


To date, the most significant procedural capability the the addition of doctors to the ARHT Westpac Rescue Helicopter has provided has been RSI capability. Of the RSIs performed so far,  a significant proportion have been for severe traumatic brain injury (TBI).

With the exception of surgical intervention (which is required in a minority of cases of severe TBI), most other essential elements of severe TBI management can be provided in the prehospital setting – airway protection, optimisation of oxygenation, prevention of hyper- or hypo-carbia, support of cerebral perfusion pressure, and ICP control.

This paper, published in the Journal of Neurosurgery in 2008, reviews the evidence around the various elements of the pre-hospital severe TBI care ‘package’.

Take-home messages:

  • a period of hypoxia (PaO2<60mmHg) is associated with a 50% mortality rate and a 50% severe disability among survivors
  • in previous studies hypoxia has been a common complication of prehospital intubation for severe TBI, with up to 57% of patients experiencing transient hypoxia lasting a mean of 2.3 minutes (note – these studies frequently involved neither an RSI as we know it nor personnel who were appropriately trained and qualified; more recent evidence points to a benefit for prehospital RSI for severe TBI provided it is done well by appropriate people)
  • Tight control of CO2 after intubation has a significant effect on survival – in one large series patients with normal CO2 on arrival to ED had a 21% mortality, those with CO2 outside the normal range had a 34% mortality
  • Manual ventilation is associated with hypocarbia
  • A single episode of hypotension (systolic BP less than 90mmHG) doubles mortality
  • Management of hypotension in the field improves outcome
  • Transport by helicopter for patients with severe TBI improves odds of survival compared with ground transport (OR 1.6-2.25) – this may reflect the presence of more skilled personnel on the helicopter, careful attention to post-intubation ventilatory parameters, and transport to a trauma centre.

The first ARHT case-based learning session!

This past week, we conducted the first ARHT case-based learning session for the duty crew!

While “case-based learning” may seem like a bunch of educational jargon…it can be rephrased to “sit around the table, discuss a previous job and consider the “what if” “.

I think at this point I was trying to convince people that I wasn't full of BS!

I think at this point I was trying to convince people that I wasn’t full of BS!

We assembled the team for the day which included the crewman, paramedic and doctor for a 45-50 minute session in the board room.  A huge thanks to Russell C, Leon, and Scott O. who all participated and they generated a great discussion about several aspects of this case. (next time we’ll be looking to get our pilot involved too!)

I had the opportunity to facilitate the session which was based on a relatively straight forward job that I had selected. The job involved a patient with a head injury and the focus was on the management of traumatic brain injury in the pre-hospital setting. But amazingly, the discussion covered tons of ground and we discussed all different aspects from before we leave the base, to the time we arrive at the hospital. Much of the discussion focused on CRM ideas which was very interesting.

Our team's paramedic and crewman in deep thought! We must have just been getting to the interesting part! At least the team isn't asleep!

Our team’s paramedic and crewman in deep thought! We must have just been getting to the interesting part! At least the team isn’t asleep…

Here’s a summary of our lively discussion!

Pre-job briefing: unless it was a water job (or extra equip is required) that this could/should be done en route
On scene time: Something we need to address as a team given some growing evidence that scene time doesn’t impact mortality in blunt trauma
Decision making for RSI: time to hospital played considerable role in whether to perform an RSI
Role assignment in RSI: crewman should probably be tasked with RSI checklist and scene management rather than involved in being hands-on during RSI. The doctor should hand the bougie & endotracheal tube to paramedic though  good discussion resulted about this and may be situation dependent
Team position in flight: discussion whether person who intubated should remain at head of bed (even if it was MD) during flight. Consensus that if patient is requiring infusions etc…then MD should be at the side, with paramedic at the head and crewman to his right.

We’ll be looking to roll out a few more sessions in the new year.

Some feedback from the session regarding logistics

  • Using previous jobs to generate discussion is good
  • Focus will be on picking jobs at random to improve learning but this will NOT be a means of quality assurance or control
  • Short sessions will be the goal: 20-30 minutes
  • Getting the whole team together is best, that includes the pilots!
  • All members felt this was a valuable exercise and would participate in future sessions

Again, thanks to the duty crew that day and Scott O for the pictures. See you all in the New Year.

Is there more to meets the eye to pre-hospital intubation than just a tube?

In a recent review of the literature about pre-hospital intubation in traumatic brain injury (TBI) and the potential impact of hyperventilation, Gaither et al. explore the potential confounders for outcomes in previous studies. 

The authors provide a nice overview about the “old school” rationale for hyperventilation in TBI and why it is unlikely a good idea!

Why hyperventilation thought to be beneficial in TBI: 1) decreases arterial PaCO2 with CNS vasoconstriction 2) decreased cerebral blood flow. Net result is improved cerebral perfusion pressure (CPP). However, hyperventilation after intubation may increase intrathoracic pressure, increase JVP and subsequently decrease CPP. Hypocarbia may also lead to free radical formation and cellular damage. So net result is PaCO2 of 25 isn’t a good idea! Probably best to target into something like 35.

The authors then outline the historical concerns about pre-hospital intubation (low success rates, long scene times and complications like hypoxia). However, they argue that perhaps its not the intubation itself that may confound these “worse” outcomes, but perhaps the greater potential for hyperventilation! And the detrimental effects may in fact occur post-intubation.

There’s some evidence that in pre-hospital settings where end-tidal CO2 is closely regulated (assuming high intubation success…which probably requires well-trained personnel) that patients do better if they’re intubated…just so long as we keep their ETCO2 under control! The following is a direct quote from the article:

There is a strong possibility that the negative effects of intubation that have been identified in several clinical trials may be due to a paradox: intubation may protect the airway and prevent hypoxia, but it also makes it easier to inadvertently hyperventilate. Consequently, although intubation is intended to reduce secondary brain injury, it may enhance it if specific, intentional measures are not taken to ensure proper post intubation ventilation

A nice conclusion is provide (which I fits well within the general tone of the article).

When properly performed, intubation is effective for airway protection and ensures adequate oxygenation; it also makes hyperventilation (and associated negative outcomes) easier and more likely. Optimal outcomes require choosing the right patients, achieving the highest success rates through training, and avoiding hyperventilation after intubation in patients with traumatic brain injury

This article makes a great case for well trained medical personnel who perform pre-hospital intubations and then provide the best post-intubation care possible.

Full text pdf is available here (secure area limited to ADHB staff only – ADHB has subscription access for staff to these journals through the Philson Library at the University of Auckland School Of Medicine)