Management of raised intracranial pressure

We have talked about ICP is connected to tissue shift, how and why you would measure it and what the problem of raised ICP is (reduced perfusion, tissue shift). Today, we focused on the basic management aspects.

In my humble experience, you should distinguish between basic measures (for every patient) and advanced interventions that can only be applied in specific situations.

Basic measures

The rule is: keep everything normal that might increase ICP. To this end you have to measure quite a lot.

  • Monitor blood pressure, preferrably arterial, and keep blood pressure normal and avoid blood pressure excursions, because too high BP leads to vasoconstriction and ischemia and too low pressure might lead to vasodilation (increases ICP) and reverse steal phenomena.
  • Monitor temperature and avoid fever. Hypothermia is acceptable as long as bodily counter measures can be mastered (in particular: shivering).
  • Monitor pCO2 (preferrably by arterial blood gases) and try keep it in the lower half of normal (35-40 mmHg) – the rationale is as in blood pressure.
  • Monitor SaO2 (keep it in the normal range, in the nineties) and pO2 and avoid too low saturation (ischemia!) and too high pO2 (has bad effects, at least in traumatic brain injury).
  • Monitor pH (and thus HCO3) – rationale as in pCO2, but influenced by the kidney and a lot of the other stuff.
  • Monitor hydration and input/output, keep it neutral (not too dry, not too wet) – need a Foley for that.
  • Monitor electrolytes (Na, K, Cl, Mg, PO4) and correct them, in particular, when complications occur
  • Monitor and avoid raised central venous pressure: keep the head up and straight (e.g. 30° – no real evidence out there), correct central venous pressure, avoid abdominal pressure, prefer subclavian instead of jugular vein cannulation.
  • Monitor glucose and keep it in the normal range.
  • Avoid seizures. If in doubt, treat. Eg with phenytoin (might reduce ICP) or even better topiramate or zonisamid (both probably reduce ICP by reducing CSF production).
  • Avoid pain
  • Avoid stress: minimally invasive nursing, keep stress-by-relatives to a minimum, sedate if necessary.
  • Avoid obstipation: stool softeners
  • If working down this list requires sedation or intubation at any point, do so liberally.

Advanced ICP therapy is best described in 3 tiers of increasing invasiveness. All of these measures are controversial or at lest quite involved. For most of them the  physiologic effect is unclear or unpredictable.

  1. Osmotherapy (mannitol or hypertonic saline, if hypotensive) – need to monitor osmolarity – 1-3d effects at most (good for bridging the maximum swelling of a lesion)
  2. Hyperventilation – few hours effects at most (e.g. prep)
    Deep sedation (barbiturates or propofol or inhalative agents)
  3. Therapeutic hypothermia
    Bilateral craniectomy
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Windows 8


This is not really about medicine, but filled some of my weekend – so here it is, my Windows 8 experience.

Maybe I am not cut out for using modern operating systems. I just managed the switch from Win7 and XP to OS X – worked like a charm (no pun intended). Then I was so annoyed with the waiting time in Windows 7 that I upgraded to Windows 8. I expected many problems with the UI, the start screen, but the speed increase promised so much relief that I went online to buy Win8 for our living room all-in-one touch Medion computer (not too fast, not too slow, running Win7 with Media Center for TV).

This blog entry reflects my first 20 hours.

I download the upgrade manager from the home page and start it – so far, no problems. A “compatibility check” opens, shows this neat little half circle of circling dots that replaces our old hourglass. Nice.

After about 5 minutes I begin to wonder what my computer is doing. No progress bar in sight. Frozen? What happened to the splash screens of good old Windows 98, providing you with information about new features in every step of the installation? But no, this is a modern computer with a sleek no-nonsense no-information designed UI, beautifully colored empty space without text.

After about 10 minutes it comes up with some questions and then requests me to buy the upgrade with my credit card. Then it starts downloading which is quicker than I thought. After about an hour it awakes and starts – after a few questions and an EULA – to prepare the preparatory steps (this is their lingo, not mine). As it discovers that my Bluetooth driver (which came with the computer) is not Win8 compatible, it commanda me to uninstall the driver. I call up the deinstallation goody and deinstall. After 17 minutes I become suspicious: progress of 17%. It turns out that you cannot deinstall, if an upgrade is ongoing. Yet the upgrade can’t continue with the old driver on board. You can’t kill the process. So I reboot the machine and restart the upgrade, after the compatibility check and some more questions (I have signed 3 license agreements on my computer and a few online up to this point), I am led to the purchase page for Win8. But wait, I have done that already, right?

Google reveals that you can find a secret installation directory on your C drive under C:/ESP – you can restart from there.

This time, somehow the Bluetooth driver (still happily residing in my programs list) is not so harmful, so the installation continues, requiring two more license agreements to be signed. Interestingly, each has a new list of small print texts to be exhaustively read. We end up with a check of installation readiness (“Installationsbereitschaft”) – mine is steadily decreasing, the system dies again for about half an hour without any sign of life, but we are used to that. Then a question pops up: “Do you want to install [this and that]?” I thought, I’d have signaled my wishes clearly, but yes I do. Then a message: your PC is going to reboot a few times, which can take a while. OK. Let’s see. I would watch a video, but then my TV computer is rebooting currently, so I take out my Mac and reminisce about the upgrade to Mountain Lion a few weeks ago, which took exactly 15 minutes.

A few alarms later, Windows 7 is rebooting, asking five times, whether it really should reboot. It seems to be reluctant to give up. Then it doesn’t reboot, it just hangs. I kill the PC with the power button and restart. It hangs for one hour. So far so good. Then the happy half circle, thank God, it is alive. “Preparation is going on…” No progress bar, of course. Then, after 10 minutes: “2%”. Progress. Speed. Technology. This is a new era of user friendly operating systems.

I’ll spare you the next 2 hours. It eventually came up and asked me for my email address. I know that from OS X, so I supply my information and can login. Somehow my user has been morphed from my former Win7 login to this user. The other ones have been thrown away. I start the marvelous UI, get the new start menu and there are plenty of tiles, moving and changing beautifully. So I click on Fotos to see my old fotos. But the library I had is gone. Let us reconfigure. But wait, how? Of course, change to the desktop. No problem. Win + D still works. My libraries of images, videos and stuff are gone. My media center is gone. Still, the files remain. So I add my external foto drive to the image library again and switch into Metro. Neat. Yet there are no pictures in my library. Sad. But then, after about 5 minutes: a picture. One. Only. Of about 1033. Why has it chosen this one? Is it because people are smiling on it and this is the new UI? Only smiling people.

I’ll have to google that. I start the Internet Explorer and am taken away from the beautifully animated Metro world into Desktop hell. Somehow IE doesn’t know how to live in Metroland yet. But it can search. Unfortunately, it only searches in Bing. What the heck, they must know the world even better than Google. Bing comes up with a news entry in a blog that tells me how to get IE into Metro: you have to declare it your standard browser. You cannot do that in Metro. It turns out that you can change at most 4 settings in the settings charm menu in Metro – the rest is over on the Desktop. But how do you reach settings there? You right-click on the non-existent Start menu. Then a disordered list of leftovers appears, containing good old system preferences, where you can change settings. I activate IE as the standard for all HTML and throw in a few of other file types – we are generous today. Somehow, this is not enough. I close System Preferences, restart it and – voila – you can make IE the tile explorer as well. Switch back to Metro (this is really simple, as the Start Menu is just below where it was in Win7), start it. Sadly, the search engine here is a different one than in Desktop land. So switch back into Desktop Internet options – there is a lot to change. Fiddle around with the search engines, kill Bing as an option. That’s it.

Back to Metroland. Type in Media Center. Gone. Where has it gone? Right, it is still there, but not licensed. So fire up a browser, type your email into the homepage and obtain a license key for free. Great opportunity. But the email doesn’t arrive. In Junk mail? No. Just no email.

So now I sit here without TV. Might just as well get used to all the new gestures. My touch screen, it turns out, is not perfect for Win8, because the margin is not continuous with the screen (4 mm difference). So it is not always possible to call up the task list. But you can use the mouse for it, moving it into the SW corner and down, where it shows the tasks. The SE corner is for charms, but only every third try actually opens the charm menu. The other ones just didn’t work. I also cannot close windows with gestures, but what is ALT-F4 for, anyway? The browsing experience is great, though. Nearly as good as on my IPad. Yet I cannot edit the favorites. To switch to a new tab, I need to what? Right-click the upper margin. This is not too bad, I can do that.

What is wonderful that there are always preferences at hand, in the charms menu. The choice is a bit weird, though. For instance you cannot change what you want to. Also, the search gadget doesn’t find the preferences entries.

Next, I try what actually was my reason for the upgrade. Wake-up time. Let us through the thing into sleep mode. But how? No start menu, no sleep. I might press the power button, but remember that I used that for hibernation. So reconfigure? Too much of a hassle, takes forever to find the place where you configure that. No, the answer is the Charms menu. There, hidden under Settings is a way to send the computer to sleep. Only 3 mousemoves. That is impressive. So it goes to sleep. Some flickering. Gone. Press a key on the keyboard (my touch screen is too much asleep), a beautiful homescreen comes up. How do I get rid of that? No instructions. Try some swipes. Down, left, right. Up is the answer. Than a password is required. But wait, I booted this computer without password, because otherwise my wife wouldn’t be able to watch TV without knowing my password and I have to keep those secret. So a new login for my wife? No, this would require adapting the settings once more and this takes to much time. I erase the Email and change the password. Of course, this can’t be done in Gagaland, have to switch to System Settings once more.
You know what. The Desktop actually looks the same as in Win7. Even the unique new task bar is nearly the same. The only thing is: I cannot spawn the Start Menu with my touch screen any more. Icons have grown smaller everywhere, maybe because Aero is gone. Thus I cannot use the Desktop with Touch at all.
What remains though, is the awkward way, the Desktop behaves if you have a Beamer installed, but not running. Windows appear in the virtual space of the Beamer Desktop, but are nearly impossible to pull back onto the visible Desktop.

Next step in Desktopland: inspect the System Settings. All is well, here. The backup machinery stopped to work. It nowadays only backs up your personal files and settings, because you can always pull your software out of the Internet. Haha, very funny. But finally, they reinvented Time Machine of OS X. Marvelous idea, so much innovation.
What else could they copy from OS X: the copy manager is revamped. After 20 years of despair when copying more than one object, the system doesn’t forget the rest of the copy task, if one fails. This is really brilliant. I’d probably pay for the upgrade just for that. If I hadn’t lost the TV functionality.

I’ll wait for one more day and play around. But it might be easier to buy an iMac.

Status therapy

As with many neurocritical care topics, there is no big evidence for status therapy, which is why the various guidelines differ dramatically, if only in the dose of drugs to be used. Since the german guidelines have just been released (though not online yet – hate them for it), it is time to review the basic steps (all the following is for Germany, only):

  • Status is when seizures take longer than 5 minutes (all guidelines agree on this, all original papers use different definitions)
  • If in doubt, give Thiamine 100 mg, Glucose (say 2-4 ampules of 40% dextrose) and (this is my personal recommendation and not really the guidelines) an ampule of Mg.
  • Monitor and ensure monitoring.
  • Make sure that an adequate dose of benzoshas been given
    • Lorazepam is preferred (0,05 mg/kg, at most twice)
    • Diazepam is mostly used by the Notarzt, because it needn’t be cooled – 0,15 mg/kg < 10 mg, at most twice
    • Midazolam 0,2 mg/kg can be given im or buccaly or any other way
  • If this fails, hit them with a non-sedating antiepileptic
    • Valproate 20-30 mg/kg (may be repeated with 10 mg/kg after 10 min) with 10mg/kg/min (an ampule of 300 mg a minute is ok)
    • Phenytoin 20 mg/kg (may be repeated with 10 mg/kg) with only 50 mg/min (which is why we rarely use it – takes over half an hour to be completed)
    • Levetiracetam 30-60 mg/kg (may be repeated full dose after 10 min)
    • Lacosamid is offered as an option with 5 mg/kg over 15 mins (too slow for my taste)
  • Next step, narcotic anticonvulsants(intubate, EEG controlled – Burst suppression)
    • Midazolam bolus 0,2 mg/kg, continuous infusion with 0,1-0,5 mg/kg/h
    • Disoprivan bolus 2 mg/kg, continuous infusion with 4-10 mg/kg/h
    • Thiopental bolus 5 mg/kg, continuous infusion with 3-7 mg/kg/h

All this should happen in less than an hour in the case of generalized or complex partial convulsive status epilepticus.
For non-convulsive, things go a bit slower, preferably with less sedating agents and without intubation, if possible.
Personally I often omit step 1 if the beginning of status lies back more than 15 mins (as usually is the case in the ER) as benzos probably don’t work so well then (due to internalization of GABA_A-receptors).

As last resort, our guidelines offer the following

  • Ketamine (good idea because of Glutamate antagonism) bolus of about 1 mg/kg, then 0,3-5,8 mg/kg/h
  • Magnesium
  • Lidocaine bolus 1-2 mg/kg, 1-4 mg/kg/h
  • Dexamethasone (how much?)
  • Sevoflurane and other inhalational anaesthetics

References

Mollaret meningitis

We are living in an age, where viral meningitis is rather straightforward – you really don’t need much diagnostics and therapy is not necessary, unless …

  • it really is Lyme disease
  • it recurs
  • it is one of the few virus infections that will be treatable in the future (lots of upcoming antiviral agents)

Mollaret meningitis is a rare form of recurrent “aseptic” meningitis, usually due to HSV-2 infection, which can be detected by HSV PCR. But we usually don’t do an HSV PCR on all presumedly viral meningitides. We use a case of Mollaret’s do discuss the microbiologic aspects of HSV-2 infection, the workup of viral meningitis and finally the differential for recurring viral meningitis.

References:

S1 radiculopathy

Dermatomes according to the Neuroanatomy site http://www.neuroanatomy.wisc.edu/

While we concentrated on the differential of radiculopathy in general and how to work with acute back pain patients for L5 radiculopathy last year, we worked up the gory details of clinical examination, pathophysiology and neurophysiology of S1 radiculopathy today.

Some things I learned:

  • As S1 exits between S1 and S2 (where the disc is not the problem), it usually is affected above the foramen and thus by more proximal lesions, such as a paramedian L5/S1 disc or spinal stenosis.
  • It is quite common and seems to happen without pain more often than L5 – how could you explain the many asymptomatic achilles tendon asymmetries out there?
  • As always in radiculopathy you have to examine all levels around the core region of interest (say L3-S4).

Neurophysiology can help to

  • localize the lesion (if axonal: EMG)
  • differentiate plexopathy and neuropathy from radiculopathy (use sensory nerve conduction times)
  • differentiate between demyelinating (i.e. reversible) and axonal lesions (H-reflex works particularly well for this)
  • pave the way for future neurophys investigations, in particular, if after surgery pain and neurology persists.

I am hard pressed for any references, since all this is pretty much folklore. I use the famous Stöhr/Mumenthaler (partly edited in our house) and also my favorite electric book.

Stroke MRI

When do you order an MRI in stroke? This is absolutely unclear – at least to me. We certainly know that MRI is way better than CT for practically everything, but in which situation does MRI add benefit to a patient that already has a CT? Does it help to time anticoagulation? When do you use it to identify the stroke pattern? How often does it surprise you with things like vasculitis?

Regardless of these questions, we do invoke MRI in about half of our patients. So we better know how to read them and this is what we did in today’s session: use our PACS viewer (in this case ImPaxx), review the standard sequences of stroke MRI, talk about DWI, ADC, FLAIR, SWI, blade and so on.

 

Decompressive craniectomy as an ethical problem

The world has not become simpler since Destiny-II has come out. But this only serves to illustrate that the underlying questions as to what makes life acceptable, what constitutes a life worth spending 3 weeks in ICU hell, 1-3 years in depression and predementia cognitive impairment, cannot easily be resolved. A complex topic such as decompressive craniectomy for malignant MCA stroke cannot be explained in two sentences. So we will try to lead a fruitful ethical discussion in the style of PBL – let us see what becomes of it.

Here are some important references: