Resource (1), CritCases 8 Management of Elevated ICP August, 2017, is the go to resource. Simply read the entire post over and over.
See the other resources below.
And see Dr. Weingart’s post Peripheral 3% Hypertonic Saline is Safe October 26, 2016.
Here are some excerpts from the above outstanding post [Review the post in its entirety as it is brief and practical.
A 74-year old male presents with sudden onset of ‘dizziness’ while doing minor chores in his backyard 30 minutes prior. He develops slurred speech and right sided facial paralysis and right sided facial droop.
His past medical history includes hypertension and dyslipidemia. Medications include ramipril and atorvastatin.
He is brought to the local community hospital. His initial vitals are T 37.0 HR 94, BP 198/100, RR 20, 98% room air. Pupils are equal and reactive. He is found to be aphasic. While his eyes are open spontaneously, he will not track. He obeys simple commands on the left side only intermittently. He has a dense paralysis on the right. Cardiorespiratory exam is unremarkable.
The sending hospital does not have a CT scanner available. A transport is requested to the local tertiary centre.
What is your initial differential diagnosis?
The main differential diagnosis to consider here is a left hemispheric stroke, most likely ischemic though hemorrhage is always a possibility. The dizziness suggests the possibility of posterior fossa involvement. Without a history of seizure, post-ictal paresis (i.e. Todd’s Paralysis) is unlikely. Aexpert peer reviewcapillary glucose must be expedited to exclude hypoglycemia. The acuity of this patient’s presentation makes an acute presentation of an intracranial tumour or abscess even less likely. In short, this patient needs a non-contrast CT head and capillary glucose as soon as possible.
100 minutes post symptom onset the transport team arrives in your hospital. The patient’s heart rate is fluctuating between 70-80 bpm (sinus arrhythmia), though there have been 2 episodes of bradycardia down to 30 bpm (rhythm uncertain). The patient’s blood pressure on arrival is 222/104. GCS is 11 (E = 3, V = 3, M = 5). Capillary glucose is 6 mmol/L. [To convert mmol/L to mg/dl, multiply by 18. – 108 mg/dl]
You suspect the patient may have elevated intracranial pressure (ICP). How could you confirm this?
Please see the rest of the post for incredibly clear guidance.
(2) Podcast 78 – Increased Intra-Cranial Pressure (ICP) and Herniation, aka Brain Code
July 22, 2012 by Dr Scott Weingart from EMCrit.
From 8:28 to 10:33 Dr. Weingart discusses Tier 0. And Dr. Weingart emphasizes some critical points on PCO2 including on not using the end tidal PCO2 alone to adjust ventilator settings. Dr. Weingart states that a venous blood gas is adequate for PCO2 determination:
“If the end-tidal is high then the PaCO2 is at least that high. I’ll say it again because it is really important. If the end-tidal is greater than 40 then the PaCO2 is at least greater than 40. But if the end-tidal is low it does not mean that the PaCO2 is low and the sicker the patient the more likely there is going to be a discrepancy. So if you look up your end-tidal and it is twenty, do not reduce the ventilatory rate on the vent until you confirm that with some form of blood gas. I can’t overstate this. . . . So what do I do?–I take my end-tidal down to 35 using the vent respiratory rate settings because then I know my PaCO2 is is 35 or greater and then I send a blood gas. If the end-tidal is 60 by all means increase your respiratory rate. End-tidal 22–send a blood gas. I hope I made that clear.
[So Tier 0] is just basic good housekeeping before the patient has any signs of elevation of intracranial pressure.
From 10:30 to 16:00 Dr. Weingart discusses Tier 1
Now let’s go to Tier 1. Let’s talk about that patient who [in the case study Dr. W presented at the start of the podcast] had a 6.8 optic nerve diameter on ocular ultrasound and is on his way to CT.
24% Saline if central access
From 16:00 to 17:00
Now generally, once they get past Tier One, they’re going to need ICP monitors.
There are two kinds: EVD (external ventricular drains) also known as IVDs (intraventricular drains) or intraparenchymal monitors a lot of us just refer to this by the brand name that was most popular, Camino . . . .
So really, neurosurgery should be putting in one of these devices if you are already at the point that you’re giving osmotic therapy for confirmed signs of increased intracranial pressure.
From 17:00 to 20:00, Dr. Weingart discusses Tier 2. Propofol is the one to use to lower the cerebral metabolic rate and that is going to lower the ICP.
So for Tier Two, things like propofol, heavy doses, and phenobarbitol.
Towards the end of the above section Dr. Weingart discusses individualized therapy.
From 20:00 to 23:54 [End of Podcast]
Now Tier Three usually will not be happening in the Emergency Department. Tier Three includes therapies like hypothermia, decompressive craniectomy, and a pentobarb coma where you’re really achieving burst suppression. These generally will be done in the ICU.
So you’re usually going to be working on Tier Zero, One, and Two in the ED. There might be an intracranial pressure monitor there already, for you to use as your marker of intracranial pressure, keeping it at less than around 20, and thereby allowing you to calculate cerebral perfusion pressure, keeping it at least above 60.
Also on Tier Three, but really reserved for me, for the patients who are actively herniating as opposed to just intracranial pressure increases, is hyperventilation.
Now we just said that in general you want them around 35 to 38 PCO2 [on an arterial or venous PCO2 – not just on the end-tidal CO2-see Dr. Weingart’s important warning on this above].
If you have a patient that is actively herniating in front of you, meaning that they are showing lateral signs now, they’re blown a pupil, they have hemiparesis on one side and you think they are actively herniating and neurosurgery is actively prepping the OR, you could hyperventilate them.
Not down to 20. I would take these patient generally around to 30, the maximum I’d lower is maybe 25, but 30 is probably as low as you should go unless they have a real dire need like they’re being taken up to the operating room and you’re wheeling them up there.
Now long term this is not going to be an effective strategy which is why for me it is only for herniation, not for ICP increases, because as a long term strategy it fails. The patient’s brain adjusts to that new CO2 level and you lose all the benefits but have all the adverse effects of hypercapnea.
At the very end of this podcast Dr. Weingart strongly urges us to go ahead and carefully review Dr. Scalea’s video podcast below.
To get the most out of this podcast, you must review all the thoughtful reader comments and Dr. Weingart’s replies that are also in the show notes.
One thing emphasized in the notes is the importance of an excellent neurocrtical care entubation. See and review Podcast 129 – LAMW: The Neurocritical Care Intubation
July 26, 2014 by Dr Scott Weingart
(3) Podcast 95 – Thomas Scalea on Cutting-Edge ICP Management
April 2, 2013 by Dr Scott Weingart. [This is a video podcast although there is an audio version available.]