1cmH20 = 0.72mmHg
normal ICP <15 mmHg (8-18 cm H2O) for adult, 3-7 mmHg (4-9.5 cm H2O) for child; varies with patient position
moderate elevation: increase in mean pressure >20 mmHg
severe elevation: increase in mean pressure >40 mmHg
waveform: comprised of respiratory and cardiac pulsations (Traube-Hering waves); the amplitude increases with ICP
β-waves: coarse, variably increased amplitude, frequency 1⁄2-2/min, often related to respiration
plateau waves: elevation of ICP over 50 mmHg lasting 5-20 min, precursor of further deterioration
Indications (Guy Rosenthal)
goal directed Tx ICP 1/∝ CPP
early warning monitoring to pPx herniation
Acute Monitoring
lumbar puncture (LP) - contraindicated with known/suspected intracranial mass.
intraventricular catheter/ventriculostomy/external ventricular drain (EVD) ("gold standard", also permits therapeutic drainage of CSF to decrease ICP)
Chronic Monitoring
fiber optic monitor (intraventricular, intraparenchymal, subdural), subarachnoid bolt (Richmond screw), and epidural monitor
Consider Monitoring of ICP in the Following Situations