Assessment of the Patient Flashcards
What % of head trauma cases are polytrauma?
60%
Define head trauma as a primary injury?
Immediate injury, as a result of the mechanical damage.
Define head trauma as a secondary injury?
Which come minutes to days after the primary injury.
Contusions, haematomas and lacerations are primary or secondary?
Prima
The cranial vault is a rigid structure containing (3)
Brain tissue
Blood
Cerebrospinal fluid
How does ICP increase?
An increase in the volume of any one of any of brain tissue, blood or CSF without a reduction in volume of one of the others
What defines the relationship between contents of the crania and ICP?
Monro-Kellie Doctrine.
In normal patients, as intracranial volume increases, the increase in ICP is initially prevented by a process of
isobaric spatial compensation
What does isobaric spatial compensation involve?
This involves initial redistribution of cerebrospinal fluid (CSF) from the cranial vault to the spinal compartment.
Once the process of isobaric spatial compensation is exhausted, what is the 2ry mechanism that commences?
blood also being redistributed away from the cranial vault.
What happens once isobaric spatial compensation and 2ry mechanism exhausted?
further compensation is limited, and continuing increases in intracranial volume (ICV) will result in ICP increasing sharply.
Maintenance of cerebral function is dependent on
Adequate blood being delivered to the brain
What does adequate blood being delivered to the brain rely on?
Adequate cerebral perfusion pressure (CPP).
Define cerebral perfusion pressure (CPP).
Include equation
the difference between mean arterial pressure (MAP) and ICP or cerebral venous pressure (CVP), whichever is greater.
CPP = MAP – ICP or CVP (whichever is the highest)
If ICP increase, what also needs to increase to maintain cerebral perfusion?
MAP
How does marked elevation in MAP lead to bradycardia?
Trigger a baroreceptor response, resulting in a subsequent bradycardia