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Intracranial pressure (ICP) is the pressure exerted by fluids such as cerebrospinal fluid (CSF) inside the skull and on the brain tissue. ICP is measured in millimeters of mercury and at rest, is normally 7–15 mmHg for a supine adult. This equals to 9–20 cmH 2 O, which is a common scale used in lumbar punctures. [1]
It can cause complications such as vision impairment due to intracranial pressure , permanent neurological problems, reversible neurological problems, seizures, stroke, and death. [1] However, aside from a few Level I trauma centers, ICP monitoring is rarely a part of the clinical management of patients with these conditions.
Under normal conditions, regular movements such as leaning forward, normal heartbeat and breathing can cause changes to the ICP. Intracranial monitoring accounts for this by averaging measurements over 30 minutes in non-comatose patients. Readings between 7-15mmHg are considered normal in an adult, 3-7mmHg in children, and 1.4-6mmHg in infants. [4]
For example, they dilate in response to higher levels of carbon dioxide in the blood and constrict in response to lower levels of carbon dioxide. [15] For example, assuming a person with an arterial partial pressure of carbon dioxide of 40 mmHg (normal range of 38–42 mmHg) [16] and a CBF of 50 ml per 100g per min. If the PaCO2 dips to 30 mmHg ...
An alternative definition of CPP is: [1] = where: MAP is mean arterial pressure ICP is intracranial pressure JVP is jugular venous pressure. This definition may be more appropriate if considering the circulatory system in the brain as a Starling resistor, where an external pressure (in this case, the intracranial pressure) causes decreased blood flow through the vessels.
Cushing reflex (also referred to as the vasopressor response, the Cushing effect, the Cushing reaction, the Cushing phenomenon, the Cushing response, or Cushing's Law) is a physiological nervous system response to increased intracranial pressure (ICP) that results in Cushing's triad of increased blood pressure, irregular breathing, and bradycardia. [1]
Pulse pressure is calculated as the difference between the systolic blood pressure and the diastolic blood pressure. [3] [4]The systemic pulse pressure is approximately proportional to stroke volume, or the amount of blood ejected from the left ventricle during systole (pump action) and inversely proportional to the compliance (similar to elasticity) of the aorta.
Presence of midline shift is an indication for neurosurgeons to take measures to monitor and control ICP. [1] Immediate surgery may be indicated when there is a midline shift of over 5 mm. [3] [4] The sign can be caused by conditions including traumatic brain injury, [1] stroke, hematoma, or birth deformity that leads to a raised intracranial ...