For many years, the traditional teaching was that all patients with head injury should be hyperventilated to reduce intracranial pressure on the belief that this would improve outcomes. Research that led to the updated Brain Trauma Foundation guidelines showed that head injury patients who underwent hyperventilation actually had worse outcomes related to the vasoconstriction and subsequent cerebral hypoxemia.
In the prehospital setting, the only component of the three components that are inside the skull that we can modify is the size of the blood vessels. The volume of tissue is fixed, and we do not have a way to rapidly decrease the extracellular fluid volume in the field setting. Thus by hyperventilating the patient and lowering the PCO2, we could shrink the size of the blood vessels and decrease the intracranial pressure.
Subsequent research shows the vasoconstriction that resulted from hyperventilation had a detrimental effect on the brain because of the decreased flow and therefore the hypoxemia that followed.
The guidelines state that we should target our ventilation to maintain an end tidal PCO2 to 35-40 mmHg.
The guidelines currently recommend hyperventilation only if herniation is occurring. The pressure inside the skull has risen so high that is beginning to force components of the brain through either the Foramen Magnum at the base or other openings that result in permanent brain damage and death Again the only thing we can do in the field setting to decrease the pressure inside the skull is to hyperventilate and decrease the size of the blood vessels in the brain. This is at best a temporizing measure but will buy a period of time to transport the patient to definitive care and management by a neurosurgeon. While there is a risk of some injury from the hypoxemia that would follow with hyperventilation, it is felt that that risk is offset by the immediate dangers posed by untreated herniation.
That’s why we recommend that in the presence of herniation as evidenced by a decrease in the Glasgow coma score of two from baseline, the development of fixed pupils and unilateral paralysis or the presence of Cushing’s reflex (which is a late sign), that the patient the hyperventilated. The end tidal CO2 level should be titrated to 30 mm HG
There is some emerging data from the Arizona EPIC study that suggest any hyperventilation may be bad, even with herniation. This may be related to the fact that it is very difficult for providers in the field to correctly identify herniation. We are continuing to monitor the results of that and other studies and will update the guidelines as needed
To summarize, patients with traumatic brain injury should receive adequate ventilation in oxygenation with the target of maintaining their end tidal CO2 in the 35 to 40 mmHg range.
Hyperventilation is indicated in TBI patients only when they show signs of acute herniation.
Permissive hypotension is not a fixed set of blood pressure figures used as a target as stated in the paper referenced above. It is a concept – and for the purpose of the review, the authors have used the systolic BP range of 50 mmHg to 70 mmHg or mean arterial pressure 50 mmHg.
Please refer to reference (5) by Giannoudi and Harwood at the end of the ITLS Current Thinking on DCR, in which permissive hypotension and restrictive fluid administration is explained. Here the target blood pressures of 70-90 or 50 mmHg mean arterial is used, which roughly equates to the restoration of a palpable radial pulse.
A very early review (2003) on permissive hypotension by Ken Mattox from Houston, Texas, may also be useful. Essentially, it is to prevent the “pop the clot” by injudicious administration of fluids before the patient arrives in a definitive care facility that we use permissive hypotension.
As in the publication you refer to, the majority of the studies are underpowered, thus reflecting the need for high quality adequately powered studies. ITLS welcomes results from such studies and in waiting has taken a pragmatic stance in this current thinking document.
Finally, Mattox questions the practice of using a peripheral blood pressure measuring device in assessing hypoperfusion or the effectiveness of treatment. Sixteen years after the publication of Mattox’s review, we are still in search of an alternative. New technologies are allowing novel end points in resuscitation to be investigated, which may prove more appropriate than blood pressure in the severely injured. These include near-infrared spectroscopy, measurement of skeletal muscle acid-base status and more sophisticated measures of global acid-base balance.
To the best of our knowledge, said Platinum 10 Minutes is unsubstantiated as a definitive, life-or-death standard for EMS on-scene time. ITLS Founder and President Dr. John Campbell started using the term some years ago (though it does not appear in the textbook) to illustrate the connection and corollary to the famous “Golden Hour.” That term was coined, of course, by Dr. R. Adams Cowley of the Maryland Shock Trauma Center. Astoundingly, there is a lack of solid scientific literature that substantiates that EMS standard, either.
That said, it certainly makes intuitive sense that if someone has uncontrolled bleeding, for example, and is going into uncompensated shock, the only treatment is probably found in the surgical suite. The sooner the better!
With that in mind, the ITLS Editorial Board has long supported the idea that, if definitive care will be decisive, very few activities in the EMS domain are justified if the victim is not en route to the surgical suite. Dr. Campbell believes we should strive for an on-scene time of five minutes. We allow for an on-scene time of up to 10 minutes (if the patient is not trapped or otherwise unavoidably delayed).
It would be most accurate to teach that the “Load-and-Go” situation should be decided by the end of the Primary Survey. The Initial Assessment, together with the Scene Survey (especially the mechanism of injury), tends to alert us that there is a potentially life-threatening problem, though not necessarily what that life threat is. So, if the Initial Assessment is unremarkable (and the Scene Survey doesn’t cause concern), the Primary Survey may be over. If the Initial Assessment indicates the potential for life threats, a Focused Exam or, more often, a Rapid Trauma Survey follows. By the end of the Rapid Trauma Survey (often done because of the mechanism of injury), one should know whether this is Load-and-Go or not.
That said, it may also be taught that a Load-and-Go should be declared as soon as it is recognized, whether it be because of altered mental status or an unstable pelvis and/or bilateral femurs.
So, on Page 31, we find that the Initial Assessment often (even usually) indicates the need to load-and-go. Page 30 tells you that by the end of the Rapid Trauma Survey, you absolutely must know whether load-and-go is necessary.
This paragraph is not clearly written, and in fact, may even be misleading. It is not that left-sided impacts are more deadly; it is left-sided impacts are more common, at least in the non-UK influenced driving countries.
The paragraph in the book refers to “oncoming traffic” and is referencing a child riding into an intersection/road from a perpendicular approach. Cars in the near lane (non-UK influenced countries) are coming from the left, hence the left sided impact.
Additionally, bicyclists are taught to ride curb-side in the direction of vehicle travel. Thus, if they weave into traffic, they are “broad-sided” on the left. Older kids, as it states in the book, tend to get hit from the rear because they tend to ride “in” the traffic lane, further away from the curb
On a side note, it is often taught that pedestrians (when crossing a road) and drivers (when pulling into an intersection) should look left, right and left again for a similar rational. In the non-UK influenced driving regions, the closest danger will be approaching from the left.
The statement is correct as written in the text. Author Roy L. Alson, PhD, MD, FACEP provides the following reference to support the use of this technique:
When a trauma has occurred on a baseball field, the removal of a batter’s helmet is easily done by removing the helmet as if it were a motorcycle helmet. However, with the use of the new hockey-style catcher’s mask as well as the old-style masks, this technique is not possible without manipulating the head and neck.
ITLS teaches that any type of helmet that requires manipulation of the head and neck to remove it from a trauma patient should be left in place. The airway may be managed through the mask/screen but should be removed if the airway needs to be managed and cannot be with the mask/screen in place. Be sure to pad around the helmet, neck and shoulders to fill any gaps and maintain inline spinal motion restriction.