Intracranial hypertension

 

Presentation:

Hx

·      Headache

·      Vomiting

·      Visual disturbance

Ex

·      ↓GCS

·      Cranial nerve palsies

·      Cushing reflex: ↑BP, ↓HR

Ix

·      Effacement of CSF spaces

·      Herniation

·      Loss of grey-white differentiation

 

Relevant physiology:

Monroe-Kellie doctrine

·      Fixed walls, single outlet

·      Increase in one substance comes at expense of another

·      Minimal compensatory capacity

·      ↑ Contents -> ↑↑↑Pressure

Flow determinants

·      Q = P1 – P2 / R

·      CBF = [mAP – (CVP or ICP)] / CVR

 

Goals:

Maximise P1

·      Volume

·      Pressor

Minimise P2

Physical:

·      Head up 30°

·      Loosen neck strictures

Physiological:

·      ↑PaO2

·      ↓PaCO2

·      ↓Temp

Pharmacological:

·      Hypnotic: propofol, thiopentone

·      Anticonvulsant: levetiracetam (10mg/kg bd)

·      Relaxant (prevent coughing)

·      Osmotic: hypertonic saline (1.5-6mL/kg), mannitol (0.25-1g/kg)

Surgical:

·      EVD

·      Decompressive craniectomy

Big ticket items in OR

·      mAP

·      Position

·      CO2

·      Osmotics

 

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