Acute intercranial problems Flashcards
What are the three essential volume components of the skull?
Brain tissue
Blood
CSF
What is the difference between primary and secondary injury?
Primary injury occurs at the initial time of an injury- eg impact of a car crash, blunt-force trauma that results in displacement, bruising or damage of the three components.
Secondary injury is the resulting hypoxia, ischaemia, hypotension, oedema or increased ICP that follows the primary injury
What are factors that influence ICP under normal circumstances?
Arterial pressure, venous pressure, intraabdominal and intrathoracic pressure, posture, temp, blood gases (particularly carbon dioxide levels).
What are three compensatory mechanisms to maintain a normal ICP?
Altering CSF absorption or production or displacing CSF into subarachnoid space
Changing intercranial blood volume through the collapse of cerebral veins and dural sinuses, regional cerebral vasoconstriction or dilation and changes in venous outflow.
Tissue brain volume compensates through distension of the dura or compression of the brain tissue.
What is autoregulation?
The automatic adjustment in the diameter of the cerebral blood vessels by the brain to maintain a constant blood flow during changes in arterial blood pressure.
What is the lower limit of systemic arterial bp at which autoregulation is effective?
MAP of 70
What is normal CPP?
60-100mmhg
What is CPP?
Pressure needed to ensure blood flow to the brain
What are the signs of increased ICP?
With a loss of autoregulation, the body attempts to maintain cerebral perfusion by increasing systolic BP. However, decompensation is imminent. Cushing’s triad occurs- systolic hypertension with a widening pulse pressure, bradycardia with a full and bounding pulse, and altered respirations.
