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’.
- 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.