ICP management for dummies

So you get a page that the ICPs are high. What do you do?

Step 1: Do not panic. If you panic, everyone panics.

Step 2: See the patient. Evaluate. Think. Are they sitting upright, talking to you, stating they feel great with the ICP monitor reading some absurd number? It might be wrong. Re-zero, troubleshoot, scan if you need to. Alternatively, some people live at ICPs of 50-70 - think of all the pseduotumor patients. Just because the number is high does not necessarily mean something bad is happening; the reason why elevated ICPs are bad is because of concern for decreased cerebral perfusion. If someone is neurologically intact, then they are clearly perfusing their brain. You can sit on high-grade SAH patients with ICPs in the 60s as long as they are awake and talking to you and without deficit; However, if someone is posturing with a blown pupil, then something probably has to be done about it.

Step 3: ABC - Airway, breathing, circulation first, always. Are they intubated? Do they need to be? Are they hemodynamically stable? If they are not protecting their airway, secure the airway first. If they are unstably hypotensive, push fluids/pressors/blood as appropriate - because if you send an unstable patient to CT and they code in the scanner, you're retarded

Step 4: ICP algorithm

- First thing, get the head of bed up, ensure neck is not excessively extended, or worse, flexed. This sounds really small but ensuring great venous drainage can buy you a lot of ICP lowering benefit. The only thing that should stop you from doing this is (very) unstable T/L spine fractures - which is why you should radiographically clear spines on any TBI as soon as possible, in anticipation of this occurring in the future, so you're not hurridly looking for total spine scans when your patient is herniating. I was once told by a team that they could not sit up a patient with very elevated ICPs because of straight-leg precautions after angio. Weigh the risk of groin hematoma vs rapid death from herniation, realize why this is absurd, and get the head of bed up. In the very least, you can do reverse-T.

- Second thing, assuming they are intubated, which people with ICP monitors often are, increase resp rate. Learn how to work your hospital ventilators so you know how to do this. This move does not buy you long-term ICP relief, but it gets you a rapid lowering that buys you time to think and plan your next moves. Reiteration: this is not a viable option for ICP management in any time-course longer than a few hours. You will get rebound effects, and after a while you will get worsening of ischemia from lower oxygen delivery to brain. A second thought: look at the rest of the parameters of your vent while you're there - if the PEEP is absurdly high, consider lowering it to improve venous drainage. Preventing herniation takes precedence over ARDSnet protocols or whatever else. Get an ABG to confirm no CO2 retention but don't wait for the results before you change the rate.

- Third, hyperosmolar therapy. Mannitol vs hypertonic saline. They both have rebound effects - the brain parenchymal osms will reset, and then you will get rebound edema. This happens much faster with mannitol than with hypertonic saline; mannitol buys you a few hours, with hypertonics you get about 24-48 hours. This is why we only use mannitol when we are about to crash someone to the OR for decompression, or if you can't get your serum osms up with hypertonic saline alone for whatever reason. Otherwise, I will always use 3% first. FYI a 250cc bag of 3% pushed at max speed delivers the same salt load as a 25cc bolus of 23% saline and you don't have to deal with an ICU team getting antsy about central lines. FYI#2 never allow central line placement to delay OR in someone who needs it stat; if its really needed, anesthesia can do it under the drapes while you operate. How much hypertonics can you give? I start getting nervous when Na>160 and Osm>320. At that point, if its not working, its not working and you should try something else.
NB: problematically, if the BBB is compromised, the hypertonics will go directly into that tissue and draw fluid in and actually worsen edema. This isn't a problem if your ICP issues are from a traumatic acute subdural, but it is a big problem if they are from a big ischemic stroke -- all the mannitol will go into the bad side and swell and crush the good side even more.

- Fourth, sedation. I like boluses of propofol, which is often rapid and very effective at lowering ICPs, as long as blood pressures will tolerate. From subjective experience, propofol has more ICP lowering effect than other things, like versed or precedex, but I have no objective evidence to support that. Pushing sedation of whatever agent of your choice is a fast and effective way of both lowering ICPs and (theoretically) of lowering cerebral oxygen demand. This is titratable - you can go from a few propofol boluses to get someone through a procedure or an event, all the way to sedating someone into burst suppression for recalcitrant ICP issues. If you're going to burst suppress, pentobarb >> extremely high dose propofol (i.e. 200mcg/kg/hr).

- Fifth, paralytics. When all else fails, you can put people on drips of non-depolarizing paralytics; this is especially helpful for people who are bucking the vent or shivering etc and you think this movement is contributing to ICP elevation. NB: most people prefer cis drips for this because of its predictable pharmacokinetics, whereas for roc or vec, the elimination is non-linear is if you put people on a drip of roc or vec for several days, it can take them > 24-48 hours to wake up and start moving, *even if* their train of fours show 4/4 twitches, so give people generous amount of time before you start brain death testing. You can have up to 80% residual neuromuscular blockade and have 4/4 twitches. Needless to say, do not remove your ICP monitor until they wake up, because you won't have an exam to follow.


Side notes:

- figure in early whether or not people will be surgical candidates. In people who are not surgical candidate, I would use exclusively salt, sedation, and paralytics and only use hyperventilation transiently to get someone through an ICP spike; I wouldn't use mannitol unless I couldn't get their osms high enough with Na alone.

- in people with EVDs, draining off CSF (or lowering the drain) can be an excellent option to temporarily lower ICPs, especially if there is a hydrocephalus component. If you get a dramatic ICP response to the drainage of a relatively small amount of CSF, that tells worlds about the ventricular compliance and about where you may be sitting on the pressure-volume curve.