ICP Monitoring

05 November 2004

ICP <10 mm Hg is normal

Severe or uncontrolled when ICP>40 mm Hg for >15 minutes

A waves or plateau waves

Large increases above baseline to max 50-100 mm Hg for 5-20 min

Associated with ICP>20 & with neurological symptoms related to pressure

As baseline ICP increases, A waves increase in magnitude & frequency

Indicate intracranial spatial compensation has been exhausted

Associated with increased cerebral blood volume and decreased cerebral blood flow

B waves

Rhythmic oscillations about every minute with amplitude max of 50 mm Hg

Partly related to depression of consciousness

Often found in association with periodic breathing

May disappear with mechanical ventilation

C waves

Rhythmic oscillations up to 20 mm Hg with frequency of 4-8/minute

Associated with Traube-Herring-Mayer blood pressure waves.

A waves important, B & C waves of little usefulness in patient management

ICP waveforms

A or plateau waves in raised ICP

B waves in raised ICP