Supraglotic Airways and ICP

[Snafu3532]

Short and sweet: In a situation of a trauma patient with increased intracranial pressure(ICP), would a supraglotic airway (i.e. king, combitube, LMA, etc.) cause a greater increase in ICP (say, compared to laryngoscopy and ET tube placement) due to its constant pressure on pharyngeal structures?

Back story (for those who are interested): In medic class we were discussing a scenario of head trauma patient (I'll leave out the details for now and add them later if they become pertinent) who seemed to be decompensating and required airway management. The area I'm in is largely advocating the use of supraglotic airways over intubation in the prehospital setting and I asked if a supraglotic airway would be problematic in this situation as the sustained pressure would might a more significant increase in ICP over the breif pressure required to use a laryngoscope and intubate. My instructors were unable to provide an answer so I figured I'd pose the question to The City.

Thanks in advance for any enlightenment anyone can provide.

[wrmedic82]

Short and sweet: In a situation of a trauma patient with increased intracranial pressure(ICP), would a supraglotic airway (i.e. king, combitube, LMA, etc.) cause a greater increase in ICP (say, compared to laryngoscopy and ET tube placement) due to its constant pressure on pharyngeal structures?

Back story (for those who are interested): In medic class we were discussing a scenario of head trauma patient (I'll leave out the details for now and add them later if they become pertinent) who seemed to be decompensating and required airway management. The area I'm in is largely advocating the use of supraglotic airways over intubation in the prehospital setting and I asked if a supraglotic airway would be problematic in this situation as the sustained pressure would might a more significant increase in ICP over the breif pressure required to use a laryngoscope and intubate. My instructors were unable to provide an answer so I figured I'd pose the question to The City.

Thanks in advance for any enlightenment anyone can provide.

This is my take. If you have to take over someones airway in the trauma setting, the question you should ask is which airway is the most appropriate? Most people would agree the the ET tube is the way to go because its more secure. And I completely agree. However the longer it takes to intubate your patient the higher the likelihood of increased ICP. So my view on supraglottic vs. endotracheal is which is quicker to obtain in regards to which airway is appropriate. With easy airways I would happily go for the ET tube, however for more difficult airways I prefer not fumble around trying to get the tube due to risks involved and go for a king (my personal preference) or combitube.

[Snafu3532]

Okay I've been thinking about this more and want to rephrase my question. To be perfectly clear this question is not about airway management. There is unquestionably a lot of consideration that goes into selecting the appropriate airway for a patient and can be very specific to situation and preference.

What I'm wondering is if the nerves in the oropharynx that cause ICP, or the vagus nerve and its reflexive bradycardia for that matter, would be continuously stimulated by a supraglotic airway due to the constant pressure of the pharyngeal/esophogeal balloons, or if they would become conditioned to such a stimulus and these responses would subside after the initial insertion.

I know the tactile receptors of the skin do not undergo adaptation and it is thalamic filtering that causes you to not feel the clothes on your back, etc. I'm wondering if the cranial nerves undergo adaptation and the reflexive increase in ICP and bradycardia of oropharyngeal stimulation would eventually subside.

I hope this helps a little bit. If someone wants to offer input on airway selection in light of any answers to this, that is just a bonus. Perhaps if the option of simple premedication with lidocaine/fentanyl is out due to constant reflex stimulation, what other avenues could one pursue?

[Paramagic]

To be honest, I'm not sure how much it would matter. The problem with head injured patients and their raise in ICP is loss of autoregulation. So where you would normally have a spike in ICP from a stimulus that would then subside, with the head inured patient that spike becomes a plateau.

The Australians have shown us that careful and appropriate pre-hospital RSI in head injured patients, with consideration for reduction or elimination of reflexes using ongoing paralysis and good sedation, will actually lead to a favourable outcomes. So I would recommend properly performed RSI over anything else in this cohort of patients.

If you cannot RSI and the patient needs their airway manged, then use whatever it is that you have available.

[Timmy]

After a quick search I struggled to find any substantial articles or documentation to suggest a supraglottic airway would affect ICP directly, rather ICP would cause oedema to various pathophysiological orientations such as sixth never palsy or Papilledema but these are not directly related to trauma. I did read an article which suggested that patients with head injury -laryngoscopy and intubation may lead to increased intracranial pressure

in the unanaesthetised patient, which proves the importance of RSI.

In the context of a trauma patient with raised ICP your priority is to secure the airway and provide ventilation support to promote oxygenation and to improve cerebral perfusion. The importance of providing good pharmacology (paralytics, sedatives and analgesia) to these patients in the form of an RSI would substantially decrease the associated risks such as reflexive bradycardia, risk of aspiration from vagus nerve irritation ect.

Medication management and administration is your key player in decreasing ICP, you would need to weight up your options… Would my LMA cause a rise in the ICP enough to potentially impact on a negative patient outcome? Or would poor airway management contribute to negative patient outcome? I think proper airway management would always supersede any associated risk of never irritation.

In Australia both in the intrahospital and pre hospital setting the use of Supraglottic Airways in trauma patients is rarely indicated, the gold standard being RSI with ETT and ventilation, but you must use what you have available.

[NYCEMS9115]

OPA with BVM is your initial treatment along with cervical stabilization. The patient needs a Neuro-surgeon not EMS. If you can maintain the airway with BLS measures; you shouldn't waste time with Advance Airway Interventions. Especially, on traumatic patients. Care would be O2, LB/Collar, Reverse Trendenlenberg, V/S, and Reassess; ALS should be done enroute to the ER. Golden Hour... All the best...

[Timmy]

I tend to disagree, coming from a rural area were 90% of our paramedics are ALS qualified I think RSI, ETT and Ventilation are more than indicated in patients with head trauma and raised ICP. The “Golden Hour” is generally not possible were I live so good ALS/Intensive Care on scene is paramount to a positive patient outcome. The more you can stabilise the patient (Pharmacology and airway management) before movement the better, we tend not to “scope and run” here.

[Snafu3532]

Thanks for all your replies. Unfortunately we do not have RSI in my area, the best we have is sedation with a King airway which is what inspired my questioning to begin with

As for the amount of time for airway management, I think the source of the "scoop and run" mentality is from a lack of understanding of continuity of care. Although surgery is the definitive care for trauma, before that can happen the patient is going to be intubated at some point -- whether that's by the anesthesiologist in the OR, by the physician at the ED or by the paramedic in the field, the 2 minutes of the "golden hour" for airway management is going to be used at some point along the way. It's a matter of where and when, and there is a benefit to sooner rather than later.

[chbare]

Thanks for all your replies. Unfortunately we do not have RSI in my area, the best we have is sedation with a King airway which is what inspired my questioning to begin with

As for the amount of time for airway management, I think the source of the "scoop and run" mentality is from a lack of understanding of continuity of care. Although surgery is the definitive care for trauma, before that can happen the patient is going to be intubated at some point -- whether that's by the anesthesiologist in the OR, by the physician at the ED or by the paramedic in the field, the 2 minutes of the "golden hour" for airway management is going to be used at some point along the way. It's a matter of where and when, and there is a benefit to sooner rather than later.

If you check the literature, you will find a couple of surprises. First, the "Golden Hour" is essentially a bed time story. Next, you will find that the literature is conflicted on rather pre-hospital RSI is of benefit to pre-hospital head injuries or actually harmful in many cases. If you sedate somebody and use brutane to insert a King, I have to question the need to actually insert said airway in the first place. A six year old kid with an acute abdomen is going to be intubated prior to OR, so why not intubate these people sooner than later? Unfortunately, there exists a significant amount of ambiguity when it comes to intubating patients based on their predicted "clinical course."

Take care,

chbare.

[usalsfyre]

OPA with BVM is your initial treatment along with cervical stabilization. The patient needs a Neuro-surgeon not EMS. If you can maintain the airway with BLS measures; you shouldn't waste time with Advance Airway Interventions. Especially, on traumatic patients. Care would be O2, LB/Collar, Reverse Trendenlenberg, V/S, and Reassess; ALS should be done enroute to the ER. Golden Hour... All the best...

Maybe in NYC, but considering the hour+ transports we have at times to get to a neurosurgeon, using BVM w/OPA would be very, very suboptimal to say the least. Plus, other than maintaining the head in a neutral position, what does cervical stabilization do for ICP? It's very hard to put the head of the bed at 30 degrees with the patient on a board...

There IS evidence that RSI, done well with adequate pharmacology and post-intubation management is good for outcomes. Too many paramedics do RSI (and for that matter intubation)poorly for me to trust just anyone with a laryngescope.

To answer the OP's question, adequate pain control (first and foremost) and sedation should eliminate any problems. However, outside of the unconscious patient with truisms, I'm not sure sedating and placing a supraglotic airway in the non-NPO patient is a good idea.