Intracranial Pressure Monitoring Pdf Download
Joao Charlesbois
This method is used if monitoring needs to be done right away. A hollow screw is inserted through a hole drilled in the skull. It is placed through the membrane that protects the brain and spinal cord (dura mater). This allows the sensor to record from inside the subdural space.
According to the Monro-Kellie theory, the cranial compartment is incompressible, and its contents (blood, CSF, and brain tissue) are in an internal milieu of volume balance; thus, an increase in one must be offset by a reduction in the other two components. Intracranial pressure (ICP) guided therapy has been the cornerstone in managing severe traumatic brain injury. ICP monitoring allows for judicious use of interventions with a defined target point, thereby avoiding potentially harmful aggressive treatment. This activity outlines the current recommendations for intracranial pressure (ICP) monitoring and reviews the role of current invasive and noninvasive monitoring methods. The activity also addresses the need for the collaborative efforts of an interprofessional team to minimize complications regarding the process and thereby safeguard patient safety.
Objectives:
- Identify the indications for ICP monitoring.Describe the equipment, personnel, preparation, and technique regarding ICP monitoring.Review the evaluation of the potential complications of ICP monitoring.Outline interprofessional team strategies for improving care coordination and communication to advance care bundle approaches in ICP monitoring and improve clinical outcomes.
Typically, ICP lowering therapy initiates when ICP is greater than 20 to 25 mm Hg.[2] Refractory elevated ICP reduces cerebral perfusion pressure (CPP), thereby accounting for cerebral ischemia and initiating herniation syndromes that eventually lead to death.[3][4]
The application of multimodal monitoring (MMM) in conjunction with adherence to ICP-guided therapy has been the cornerstone in managing severe traumatic brain injury. Thus, ICP monitoring allows for judicious use of interventions with a defined target point, thereby avoiding potentially harmful aggressive treatment. Brain Trauma Foundation (BTF) guidelines during patient care bundle approaches have shown positive outcomes as well as the minimized cost of acute care.[5][6]
According to the Monro-Kellie theory, the cranial compartment is incompressible and its contents (blood, CSF, and brain tissue) are in an internal milieu of volume balance; thus, an increase in one must be offset by a reduction in the other two components. The Monro-Kellie hypothesis is based on a pressure-volume relationship that tries to keep the non-compressible aspect of the skull in a steady state.[7][8] CSF and cerebral blood volume (CBV) are the primary buffers for any extra volume increment.
Harvey Cushing established the clinical and physiological significance of this doctrine in the twentieth century by confirming Burrows' findings of the CSF's role in intracranial dynamics and the existence of three volumes that operate as compensators for volume depletion or insertion inside the skull.
According to Monro and Kellie's 1783 pressure-volume equations, when intracranial pressure (ICP) rises, vascular blood and CSF are moved as part of a dynamic counterbalance to maintain normal pressure inside the inelastic skull, while brain tissue stays unaffected. Under pathological circumstances, if one of these compartments expands or a fourth one forms (as a result of a mass-effect lesion such as a tumor or hematoma), one or more of the other components must contract to prevent any subsequent rise in ICP. Since the parenchymal compartment is incapable of compensating for a rapid increase in ICP, CBV and CSF are responsible for this process. CSF is the primary buffer mechanism; it migrates into the perimedullary subarachnoid area until displaced brain structures obstruct its flow. The vascular compartment's capacity to correct for ICP is activated later and consists of lowering the CBV through jugular drainage.
In individuals with intracranial hypotension, a decrease in CSF volume may result in a compensatory increase in brain and/or intracranial blood volume. Since the amount of brain tissue is typically regarded constant, compensation would occur through an increase in blood volume, notably venous blood, because veins are more adaptable than arteries.[10] The Monro-Kellie theory may account for many MRI anomalies seen in intracranial hypotension or CSF volume depletion, such as meningeal augmentation, subdural fluid collections, engorgement of cerebral venous sinuses, prominence of the spinal epidural venous plexus, and pituitary gland enlargement.[8] As a second consequence of the lack of the buoyancy forces given by CSF, brain tissue is forced downward, resulting in herniation. These effects are amplified by gravity while the patient is standing up, and they serve as a foundation for understanding both the clinical presentations of the condition as well as the imaging results.[11]
Cerebral compliance is defined as the volume required to produce a specific change in pressure. Thus, cerebral compliance may be defined as the cranial vault's adaptive ability to increase volume.[12] The cerebral elastance (pressure resulting from a known change in volume) is interpreted as the opposition to intracranial volume growth. The pressure-volume curve is divided into three phases.[12]
Intraventricular monitoring with the aid of ventriculostomy or the use of intraparenchymal strain gauge or fiber-optic monitors is the recommendation for ICP monitoring. So appropriate monitoring devices should be available. There must be utmost care for strict adherence to aseptic conditions during these procedures. There also is the paramount importance of implementing algorithmic management guidelines in all patients with invasive ICP monitors for safeguarding all monitor sets.
An underlying assumption is that an ICP reading at one point is equivocal, and the mirror reflects the global pressure throughout the brain. However, it is confounded by the pressure gradient within the ventricular system as well as the parenchyma brain interface. The accuracy and precision over time (drift) and in vivo calibration of different ICP measurement systems are also a concern.[2][16]
As the brain ICP increases, RAP gradually falls below zero signifying exhaustion of autoregulatory capacity. There will be a right shift of the pressure-volume curve, and thereby further increase in cerebral perfusion pressure leads to the paradoxical passive collapse of the arterioles.[1]
Intracranial pressure monitoring requires an interprofessional team approach, including clinicians (MDs, DOs, NPs, and PAs), specialists, and specialty-trained nurses, collaborating across disciplines to achieve optimal patient results. The critical care nurse is essential for close monitoring of intracranial pressure and communicating any change to the medical team. The neurology and critical care nurse assists the medical team with hourly neurological and hemodynamic evaluations to ensure prompt intervention when needed. An interprofessional team working in unison with collaboration can significantly enhance patient outcomes in patients undergoing intracranial pressure monitoring.
The advantage of the ventricular monitoring device is the facility for egress of CSF in cases of a sustained rise in ICP (greater than or equal to 20 mm Hg for 5 minutes or longer), but the disadvantage is that simultaneous monitoring, as well as CSF drainage, is not possible. The amount of CSF to be drained can be guided as per the recommended target ICP (commonly set as 10 mm Hg) or can be aided with the visual guidance in improving the ICP waveform analysis obtained from the concurrent application of intraparenchymal monitors or through clinical neurological examination.[20] Care always needs to be taken in preventing paradoxical upward transtentorial herniation due to over jealous drainage of CSF.
The ICP monitoring devices get removed once the ICP is normalized with sustained or improved clinical neurology (motor score at least 5) for at least 48 to 72 hours without any interventions. In cases of ventricular devices, the EVD can undergo clamping, or more ideally gradual increment in its height (training of the EVD) is attained to watch for any clinical deterioration in the patient for at least 48 hours.
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.
It is possible to experience intense head pressure even when ICP is in the normal range, and ICP can be significantly elevated only during sleep. This is why it is helpful for your doctors to have pressure recordings over 24 hours or more to detect intermittent abnormalities and determine how well they correlate with your symptoms. Also, your doctor can see how different head and body positions affect ICP. In certain situations, an abnormally low pressure may be detected only after prolonged standing.
Spinal fluid pressure measured during a lumbar puncture (spinal tap) provides an accurate value for intracranial pressure only at the time of the procedure. While this will always be a valuable test to establish a diagnosis and monitor therapy, there are times when a more invasive approach is necessary. Your doctor will discuss with you the pros and cons of the various methods available to measure head pressure, and the basis for his or her recommendation. What follows is some general information to help you make an informed decision about your care and prepare you for your hospital admission.
Background: Intracranial-pressure monitoring is considered the standard of care for severe traumatic brain injury and is used frequently, but the efficacy of treatment based on monitoring in improving the outcome has not been rigorously assessed.
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