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

·      ETT patent, no PEEP, no cough

  -Physiological

·      ↑PaO2

·      ↓PaCO2 26-30mmHg (beware rebound)

·      (↓)↔Temp (same outcome)

  -Pharmacological

·      Hypnotic: propofol > sevoflurane (same outcome)

·      Anticonvulsant: keppra (10mg/kg bd), or phenytoin (15mg/kg)

·      Relaxant (prevent coughing)

·      Osmotic: 3% saline (1.5-6mL/kg), 20% mannitol (1.25-5mL/kg)
or 4 x 100mL for each

o   Caution: heart failure, renal failure

  -Surgical

·      EVD (aim ≤30mL/h)

·      Decompressive craniectomy

 

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