Intracranial pressure - stualis

[ArchivalUser]

stualis,

the act of performing intubation...doing laryngoscopy is very stimulating....sympathetic discharge of major order happens...and increase ICP as well as IOP.....
this is extra info....i know does not answer the q....
despite how high the ICP is....intubation is carried out...whenever warranted....but full measures are taken to blunt sympathetic discharge...

back to your question...
agree hyperventilation is controversial...coz it is effective only in the first 24 hrs...or maybe even less...

and whenever a pt of increased ICP comes...4-5 things happen all at once...
1. hyperventialtion p intubatiion
2. mannitol
3. steroid.
4. head elevation
5. benzos are given to decrease CMRO2
6. lasix is also used in some instances

i do not know the answer for sure...but i would choose mannitol...if i had to...

[ArchivalUser]

For hyperventilation, intubation is usually required (unless you try to hyperventilate someone using non-invasive ventilation), but hyperventilation is usually fast (the effect transient).
Mannitol takes a couple of minutes to take effect.
The effect of head elevation is controversial (see explanations)


if the cause of the intracerebral pressure is traumatic brain injury, corticosteroids do more harm than good.
barbiturates are more effective in decreasing CMRO2 than benzos, 50% of the CMRO2 is caused by 'electrical activity' (this is what is decreased by barbiturates), but no matter what hypnotic you use: you should aim at a burst supression rate >90%. The other 50% of the CMRO2 derives from the basal metabolic rate of the brain cells, this can only be decreased by... cooling!
Controversies exist regarding the use of ketamin in pts w/ elevated ICP. Most books mention this as a contraindication to the use of ketamin, newer studies do not support this thesis. As ketamin is an antagonist at the NMDA receptor (gluatamate!), a rise in intracellular calcium levels, which are associated with an increased cell metabolism, is prohibited by its use. Why did ketamin led to an increase in ICP in older studies? The patients were not intubated or ventilation was not adapted to the increase in CO2 sometimes associated w/ ketamin application (sympathomimetic effects!), so the ICP was a consequence of an elevated PaCO2. The effects of ketamin on ICP are not seen in pts during controlled mechanical ventilation.

normovolemia is extremely important in patients with intracranial hypertension, so the unreflected use of mannitol and frusemide should be avoided (mannitol will cross the blood-brain barrier (BBB) at some time, as the BBB is often disturbed, esp in pts w/ TBI. Administration of mannitol will further increase tissue swelling, in this case, frusemide will be beneficial). An alternative to mannitol may be hypertonic saline (7.2% in 6% HES 130/0.4), 2mL/kg, but electrolyte monitoring is mandatory.

Head elevation is often recommended, as it is in almost every patient that is intubated (30 degree). As the intracranial veins are enclosed in a rigid housing (the skull!), the increased ICP will be transmitted to these veins and possibly compress them (Starling resistor! An effect also seen in the lung in pts w/ an asthma attack or severe COPD). So lowering the central venous pressure by head elevation may not be effective.

Regarding the increase in ICP during intubation: in modern medicine wonderdrugs like remifentanil are readily available to blunt sympathetic responses, rocuronium (given as 4xED95 = 1.2mg/kg) can be used for intubation (in combination with thiopental or propofol). This is a concept for a modified rapid sequence induction.

Other parameters to aim at:
Strict normoglycemia, PaO2>100mmHg, PaCO2 35-40mmHg, CPP>=70mmHg, normal electrolyte levels.

Monitoring of a patient w/ an increase in ICP:
standard ICU monitoring (BP, HR, CVP, urinary output)
pressure monitoring (intracranial pressure probes)
EEG (burst suppression!)
transcranial doppler (flow acceleration!)
(bulbus venae jugularis oxygen saturation, lactate!)
(tissue oxygenation: PtiO2)
the latter 2 are rarely used in the ICU setting.

[ArchivalUser]

one thing in mind:
When we do intubation in these patients we have to paralyze and sedate patient right? so risk for vasovagal reaction is considerably decreased. The fastest as TH and others said is hyperventilate, the most reliable is mannitol

[ArchivalUser]

bdj,

its not vasovagal....its sympathetic discharge....
paralytic agents do not blunt it....the pt just doesn't move..just paralyze...no effect on sympathetic system...
no matter what you use it is very hard to blunt it.....
i have been through it many a times...

[ArchivalUser]

bdj,
but i like your explaination........fastest is hyperventialtion and most reliable mannitol!
i might just have to choose hyperventilation now....

[ArchivalUser]

sorry yes I got a senior moment and just realized...
Sympathetic. What happens cricoid is that in these cases we normally would request the most skilled person to do the intubation; as you know it should take less than 60 seconds for somebody with those qualifications to intubate the patient. As soon as the tube is in you will start hyperventilation. So whatever increase in ICP will be extremely transient and should not have a severe enough effect to walk away from it or consider mannitol over hyperventilation. You can start treatment within 60 seconds whereas with mannitol you need more time, you need to calculate, get it, set the infusion and wait for its action. So at least in real life the answer is hyperventilate.

[ArchivalUser]

you are the CHEF!!!!
got it boss.................thanks.

[ArchivalUser]

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