Management of intracranial pressure in neurocritical care remains a potentially valuable target for improvements in therapy and patient outcomes. Surrogate markers of increased intracranial pressure, invasive monitors, and standard therapy, as well as promising new approaches to improve cerebral compliance are discussed, and a current review of the literature addressing this metric in neuroscience critical care is provided.
Key points
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The management of intracerebral hypertension is a mainstay of neurocritical care, although invasive monitoring remains controversial in certain populations of acquired brain injury.
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Conservative measures to promote improved intracranial compliance should be in place in all patients with acquired brain injury.
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The type of ongoing disease should determine the type of intracranial pressure monitor placed. Limited options exist for noninvasive monitors for intracranial pressure (ICP).
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Interventions for management of ICP involve hyperventilation, hyperosmolar therapy, CMR o 2 (cerebral metabolic rate of oxygen)-based strategies, surgical treatment options, and N -methyl- d -aspartate receptor antagonists.
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Individual intensive care units should have an established treatment algorithm in place to manage increased ICP.
Background regarding intracranial pressure monitoring
Introduction
Neurocritical care has evolved to include enhanced diagnostic and treatment options over the past several decades. Central to this care delivered in the neurosciences intensive care unit (ICU) is multimodality monitoring of patients with brain injury. Perhaps second to the bedside clinical examination, the most universal continuous neurologic monitor is likely the intracerebral pressure monitor. The management of increased intracranial pressure (ICP) is discussed.
Neuro-monitoring of patients with acquired brain injury is performed for patients most severely affected by their central nervous system injury. The Glasgow Coma Scale (GCS) allows rapid classification of the severity of the brain injury and fosters improved communication regarding a patient’s clinical status. This scale classically describes patients with traumatic brain injury (TBI), but can be used to communicate the neurologic status of patients with brain injury from other causes ( Table 1 ). Patients with GCS scores of 8 or less have significant neurologic injury. These patients often have abnormal neuroimaging to include computed tomography (CT) scan findings such as a skull fracture, traumatic intracranial hemorrhage, or contusional injury. Rapid evacuation must occur from the point of injury to the ICU for management of the patient’s critical care needs, including airway management, mechanical ventilation, neurosurgical evaluation, and neuromonitoring. These modalities may include jugular venous oximetry, brain tissue oxygenation (Pbt o 2 ), cerebral microdialysis, electroencephalography (EEG), advanced neuroimaging, and ICP monitoring. Guidelines for the use of multimodality monitoring of patients with severe brain injury are published by the Brain Trauma Foundation and have been instrumental in improving care with evidence-based recommendations. Guidelines are also available for the prehospital management of severe TBI, prehospital care of combat-related head trauma, and surgical management of TBI. These guidelines can be obtained online from the Brain Trauma Foundation at http://braintrauma.org . A tool to assess individual management compliance with published guidelines is available at http://tbiclickandlearn.com . European guidelines for the management of severe head injury have been published by the European Brain Injury Consortium, which also discusses issues of neuromonitoring and ICP. The recommendations in these guidelines have been suggested to serve as a general reference for the management of other mechanisms of brain injury in neurocritical care.
| Eye | Motor | Verbal | |||
|---|---|---|---|---|---|
| Eyes open spontaneously | 4 | Follows commands | 6 | Oriented, alert | 5 |
| Localizes | 5 | ||||
| Withdraws | 4 | Confused, appropriate | 4 | ||
| Eyes open to voice | 3 | Flexion | 3 | Disoriented, inappropriate | 3 |
| Eyes open to pain | 2 | Extension | 2 | Incomprehensible speech | 2 |
| No response | 1 | No response | 1 | No response | 1 |
Goals in the critical care management of patients who experience brain injury must address arrest of any ongoing injury, preservation of neurologic function, prevention of medical complications of critical illness, and improvement in overall outcome. These patients should be evaluated in a center with specialized neurologic care, such as neurosurgery and neurointensivist care, where decisions about neuromonitoring, including ICP monitoring, can be best made. Although still controversial, ICP monitoring is the only available technology shown to guide interventions and predict outcomes, especially in TBI. Its use is widely considered a standard tool in the neurocritical care unit. Information obtained by monitoring a patient’s ICP can be used to prognosticate and to follow progression of intracranial disease. It also aids in the assessment of global perfusion metrics such as cerebral perfusion pressure (CPP). The merits of ICP monitoring-based treatment protocols and their influence on patient outcome have been recently investigated in a randomized trial, which is further discussed.
Mechanism and Potential Conditions Associated with Increased ICP
Although TBI is the disease process commonly associated with alterations of ICP, different types of brain injury can result in increased ICP. Patients with ischemic and hemorrhagic stroke, aneurysmal subarachnoid hemorrhage, and noncommunicating hydrocephalus encounter issues with intracerebral hypertension. Other critically ill populations with metabolic, infectious, or hemorrhagic space-occupying lesions, postcirculatory arrest, hyperthermia, or electrolyte abnormalities may also have increased ICP, with signs of poor intracranial compliance. The relationship between intracranial volume and ICP was initially described by Monro and later by Kellie in 1783 and 1824, respectively. Given that the skull remains fixed and rigid with a static volume of brain, blood, and cerebrospinal fluid (CSF), any increase in 1 of these 3 components results in the displacement of another of the 3 components outside the skull. As volume continues to increase, intracranial compliance, defined as the change in volume/change in pressure, moves from a near-linear relationship to an exponential relationship; small changes in volume result in large changes in pressure ( Fig. 1 ). This situation results in alterations of the slope of the ICP waveform. An example of an appropriate ICP waveform is shown in Fig. 2 .
Related posts:
Moderate and Severe Traumatic Brain Injury
Neurocritical Care in Neurosurgery
Managing Subarachnoid Hemorrhage in the Neurocritical Care Unit
Seizures and the Neurosurgical Intensive Care Unit
Microdialysis in the Neurocritical Care Unit
Parenchymal Brain Oxygen Monitoring in the Neurocritical Care Unit
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