Physiology of intracranial pressure (ICP)
1. Intracranial pressure dynamics: Intracranial pressure is the pressure of cerbrospinal fluid inside the skull.Normally the cranial vault is a closed box and non compliant structure containing volume of approximately 1500 ml ,comprissing 88% brain matter ,7.5% blood and 4-5 % cerebrospinal fluid . Monrroe kelle hypothesis concludes that any increase in the volume of an intracranial element must be met with an equal compensatory decrease in the volume of another component, or pressure will increase. Because of the skull’s noncompliance, uncompensated changes in the volume of any given component may have an impact on ICP, with a potential exponential increase in ICP.(1). Normal …show more content…
The metabolic regulation of arteriolar vascular resistance is variably affected by CO2, O2, pH/lactate formation, adenosine, and nitric oxide. Neurogenic regulation refers to sympathetic tone on the cerebral arteries leading to mild tonic vasoconstriction, allowing for higher limits on the autoregulation curve; in contrast, the parasympathetic nervous system plays little role in cerebral autoregulation . Measuring the limits of cerebral vascular autoregulation is possible using transcranial Doppler technology by comparing beat-to-beat spontaneous variability in systemic BP with CBF velocities . If CPP levels fall below the lower limit of autoregulation, CBF will fall and contribute to oligemia. If CPP exceeds the upper limit of autoregulation, an excess of brain. This is an uncoupled increase in CBF, or luxury perfusion. Recent animal data suggest that the lower limit of cerebral autoregulation rises as ICP increases, which might mandate a progressively higher CPP goal to maintain constant CBF
1. Intracranial pressure dynamics: Intracranial pressure is the pressure of cerbrospinal fluid inside the skull.Normally the cranial vault is a closed box and non compliant structure containing volume of approximately 1500 ml ,comprissing 88% brain matter ,7.5% blood and 4-5 % cerebrospinal fluid . Monrroe kelle hypothesis concludes that any increase in the volume of an intracranial element must be met with an equal compensatory decrease in the volume of another component, or pressure will increase. Because of the skull’s noncompliance, uncompensated changes in the volume of any given component may have an impact on ICP, with a potential exponential increase in ICP.(1). Normal …show more content…
The metabolic regulation of arteriolar vascular resistance is variably affected by CO2, O2, pH/lactate formation, adenosine, and nitric oxide. Neurogenic regulation refers to sympathetic tone on the cerebral arteries leading to mild tonic vasoconstriction, allowing for higher limits on the autoregulation curve; in contrast, the parasympathetic nervous system plays little role in cerebral autoregulation . Measuring the limits of cerebral vascular autoregulation is possible using transcranial Doppler technology by comparing beat-to-beat spontaneous variability in systemic BP with CBF velocities . If CPP levels fall below the lower limit of autoregulation, CBF will fall and contribute to oligemia. If CPP exceeds the upper limit of autoregulation, an excess of brain. This is an uncoupled increase in CBF, or luxury perfusion. Recent animal data suggest that the lower limit of cerebral autoregulation rises as ICP increases, which might mandate a progressively higher CPP goal to maintain constant CBF