What are the three components of the Monro-Kellie hypothesis?
What are the three components of the Monro-Kellie hypothesis?
Key Points
- The Monro-Kellie Doctrine describes the relationship between the contents of the cranium and intracranial pressure.
- In non-pathological states, three components exist in equilibrium to maintain normal intracranial pressure, the brain tissue, the blood, and the cerebrospinal fluid.
What is the difference between ICP and CPP?
Cerebral perfusion pressure (CPP) is the amount of pressure needed to maintain blood flow to the brain. Mean arterial pressure (MAP) is the driving force that pushes blood into the brain. Intracranial pressure (ICP) is the force that keeps blood out.
How does the brain compensate for increased intracranial pressure?
Compensation typically occurs by displacing or shifting CSF, increasing the absorption of CSF, or decreasing cerebral blood flow. Without these changes, ICP will rise.
What is autoregulation in the brain?
Autoregulation of cerebral blood flow is the ability of the brain to maintain relatively constant blood flow despite changes in perfusion pressure [137]. Above and below this limit, autoregulation is lost and cerebral blood flow becomes dependent on mean arterial pressure in a linear fashion [71,72,139].
What is the clinical significance of CPP?
It is the difference between the mean arterial pressure (MAP) and the intracranial pressure (ICP), measured in millimeters of mercury (mm Hg). Maintaining appropriate CPP is critical in managing patients with intracranial pathology, including traumatic brain injury, and with hemodynamic distress, such as shock.
Which change in vital signs is indicative of increasing intracranial pressure?
Hypertension and widening pulse pressure (the difference between the systolic and diastolic BP) Bradycardia.
What is the purpose of autoregulation?
Autoregulation of blood flow is a regulatory mechanism that allows blood flow in a vascular bed to remain relatively constant during variations of arterial pressure.
What is autoregulation in psychology?
Autoregulation is a process within many biological systems, resulting from an internal adaptive mechanism that works to adjust (or mitigate) that system’s response to stimuli. While most systems of the body show some degree of autoregulation, it is most clearly observed in the kidney, the heart, and the brain.
Why do we measure ICP?
Intracranial pressure (ICP) monitoring is a diagnostic test that helps your doctors determine if high or low cerebrospinal fluid (CSF) pressure is causing your symptoms. The test measures the pressure in your head directly using a small pressure-sensitive probe that is inserted through the skull.
What is the Monro-Kellie theory?
Description The Monro-Kellie doctrine or hypothesis states that the sum of volumes of brain, cerebrospinal fluid (CSF) and intracerebral blood is constant. An increase in one should cause a reciprocal decrease in either one or both of the remaining two.
Who was George Kellie and what did he do?
1824 – George Kellie was an Edinburgh based surgeon and former student of Monro. His contribution to the doctrine stems from papers he published on the post mortem examination of two individuals that were found deceased in Leith the morning after a winter storm.
How did Monro contribute to the development of Physics?
More than two centuries ago, Alexander Monro applied some of the principles of physics to the intracranial contents and for the first time hypothesized that the blood circulating in the cranium was of constant volume at all times. This hypothesis was supported by experiments by Kellie.
What happens when CPP falls below the lower limit of autoregulation?
When CPP falls below the lower limit of autoregulation, the brain is at risk of inadequate blood flow. Compensatory mechanism by increase extraction coefficient of oxygen from blood to cerebral tissue is important in order to sustain its metabolic demand.
