Raised ICP Flashcards
What are normal ranges of ICP in adults children and infants ?
what is a good rule of thumb for raised ICP ?
Adults= 5-15 mmHg
Children = 5-7mmHg
Term infants = 1.5 - 6 mmHg
if >20mmHg = raised
what is the Monro-kellie doctrine ?
Any increase in the volume of one of the intracranial
constituents (brain, blood or CSF) must be compensated by a decrease in the volume of the one of the others
what is the first components to decrease in IC mass ?
CSF and venous blood, since they are at the
lowest pressure
how do you work out CPP?
What is normal CCP , MAP and ICP
CPP = mean arterial pressure (MAP) – ICP
CPP >70 MMhG
MAP ~90mmHg
ICP ~10 mmHg
What happpens when CPP is <50 mmHg ?
cerebral blood flow cannot be
maintained as cerebral arterioles are maximally dilated
what can damage brain lead to ?
impair or even abolish cerebral
auto-regulation (Vaso contriction/ dilation)
what happens in Cushing triad/ reflex ?
Raised ICP -
Hypertension = Increase in MAP to maintain CPP
Bradycardia = Due to vagal activity via baroreceptors from increased MAP
Irregular breathing = compression of the brainstem leads to
damage to respiratory centres
what mights cause raised ICP from blood ?
too much in vessels -
Raised arterial pressure = Malignant hyperntsion
Raised venous = SVC obstruction
Haemorrhage- SA, SD, ED, Stroke and intraventricular
what are the cause of Hydrocephalus ?
too much CSF
What are the causes of congenital hydrocephalus ?
Obstructive - Neural tube defects, Aqueduct stenosis, part of other syndromes
Communicating- Increased CSF production , Decreased CSF absorption
what are the clinical signs of congenital hydrocephalus ?
Bulging head with head circumference increasing faster than expected Sunsetting eyes (due to direct compression of orbits as well as involvement of oculomotor nerve as it exits midbrain)
what is the management of congenital hydrocephalus ?
tapping fontanelle with needle
Medium term drainage can be achieved by external ventricular drain
(EVD)
what is the advantages / disadvantages of EVD?
allows - Short / medium term drainage , continuous pressure monitoring , used if shunt fails or contraindicated
cons - Infection pathway , chamber must be kept at same height as ventricles
inpatient monitoring - not long term
what is a Ventricular shunt ? what types can you get ?
one way valve tunelled under skin
tube is placed from the ventricular system
into the peritoneum (V-P) or
right atrium (V-A), VP more common
what are cons of VP shunts ?
Extra length of tubing is provided to allow growth before revision is required V-P shunts vulnerable to infection (e.g. if abdominal infection, can track back up to brain) or kinking Most s hunts will require revision
