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.
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.
- 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)
- Hyperventilation – few hours effects at most (e.g. prep)
Deep sedation (barbiturates or propofol or inhalative agents)
- Therapeutic hypothermia