Intracranial pressure monitoring for severe traumatic brain injury
Although the current guidelines recommend the use of intracranial pressure monitoring in patients with severe traumatic brain injury (sTBI), the evidence indicating benefit is limited.
Patient data from the Collaborative European Neurotrauma Effectiveness Research in Traumatic Brain Injury China Registry, a prospective, multicenter, longitudinal, observational, cohort study. Patients with sTBI who were admitted to 52 ICUs across China, managed with ICP monitoring or without, monitoring showed a better outcome in overall survival. Nevertheless, the use of ICP monitoring makes the management of sTBI more complex and increases the costs of medical care by prolonging the patient's stay in the ICU or hospital 1).
Guidelines
The Brain Trauma Foundation (BTF) guidelines published in 2014:4th edition
A mainstay of the care of the patients with the most severe brain injuries has been the monitoring of—and treatment of—intracranial pressure (ICP). Decades ago, it was recognized that cerebral swelling after traumatic injury to the brain can lead to brain herniation syndromes, with the brain being forced under pressure into abnormal anatomical spaces, which leads first to death of those areas of the brain and ultimately of the brain itself. At the advent of contemporary critical care, technological advances to measure intracranial pressure by placement of devices within the brain became available, which allowed clinicians to titrate therapies based on objective information from intracranial pressure monitors 2).
Because of its fundamental place in the care of patients with severe traumatic brain injury (TBI) and its relationship to overall outcomes, ICP monitoring has been included in every guideline for severe TBI published by the Brain Trauma Foundation. In the developed world, ICP monitoring is routinely used, leading to a lack of equipoise for assigning patients to a “nonmonitored” arm of potential interventional trials. Therefore, in many studies, the evidence supporting the utility of ICP monitoring was observational in nature and largely found that ICP crises led to poorer outcomes 3) 4) 5) 6).
A study has challenged this paradigm by randomizing patients to protocols to treat intracranial hypertension therapies based on either an invasive ICP monitor or a clinical/radiological examination 7).
This study, performed in a region of the world where equipoise existed for a non-monitored group of patients, failed to find differences between the groups. What is clear from the literature is that intracranial hypertension is an important secondary insult after severe TBI, and its alleviation plays a pivotal role in providing good patient care to achieve optimal outcomes 8).
Recommendations
Level I and Level II A
• There was insufficient evidence to support a Level I or II A recommendation for this topic.
• Management of severe TBI patients using information from ICP monitoring is recommended to reduce in-hospital and 2-week post-injury mortality.
As noted above in the introduction to this “Part II. Monitoring” section, the Level II and III recommendations from the 3rd Edition of these guidelines were not carried forward because they were derived from descriptive studies, or from studies that do not meet the current inclusion criteria for this topic. While no evidence is available from comparative studies to support a formal recommendation, the Committee chose to re-state here the 3rd Edition recommendations. The rationale for doing so is to maintain sufficient recognition of the patient characteristics associated with risk of increased intracranial pressure. (Refer to the 3rd Edition for summary of supporting studies.).
Recommendations from the Prior Third Edition Not Supported by Evidence Meeting Current Standards
• Intracranial pressure (ICP) should be monitored in all salvageable patients with a severe traumatic brain injury (TBI) (GCS 3-8 after resuscitation) and an abnormal computed tomography (CT) scan. An abnormal CT scan of the head is one that reveals hematomas, contusions, swelling, herniation, or compressed basal cisterns.
• ICP monitoring is indicated in patients with severe TBI with a normal CT scan if two or more of the following features are noted at admission: age over 40 years, unilateral or bilateral motor posturing, or systolic blood pressure (BP) <90 mm Hg.
Changes from Prior Edition
New Class 2 studies provide evidence for recommendations that replace those of the 3rd Edition of these guidelines. See the introduction to this “Part II. Monitoring” section (above) for details about changes from the 3rd Edition.
With lack of strong evidence, it is not surprising that the use of ICP monitoring in both adults and children is variable. Although it seems intuitively obvious that having this data point would be beneficial, large observational studies in adults and now in children do not clearly support the benefit. Current guidelines for pediatric patients state that although elevated ICP is associated with poorer outcomes, it is only a level III recommendation to use ICP monitoring in children with severe TBI 9).
Recommendations from adult guidelines are slightly more firm, using level IIb evidence, stating that ICP should be monitored in patients with Glasgow Coma Scale less than 8 and an abnormal computed tomography (CT) scan or a normal CT scan in patients who meet 2 of the 3 following criteria: age >40, unilateral or bilateral motor posturing, or systolic blood pressure less than 90 mm Hg 10).
Trials
Randall Chesnut et al., conducted a multicenter, controlled trial in which 324 patients 13 years of age or older who had severe traumatic brain injury and were being treated in intensive care units (ICUs) in Bolivia or Ecuador were randomly assigned to one of two specific protocols: guidelines-based management in which a protocol for monitoring intraparenchymal intracranial pressure was used (pressure-monitoring group) or a protocol in which treatment was based on imaging and clinical examination (imaging-clinical examination group). The primary outcome was a composite of survival time, impaired consciousness, and functional status at 3 months and 6 months and neuropsychological status at 6 months; neuropsychological status was assessed by an examiner who was unaware of protocol assignment. This composite measure was based on performance across 21 measures of functional and cognitive status and calculated as a percentile (with 0 indicating the worst performance, and 100 the best performance).
There was no significant between-group difference in the primary outcome, a composite measure based on percentile performance across 21 measures of functional and cognitive status (score, 56 in the pressure-monitoring group vs. 53 in the imaging-clinical examination group; P=0.49). Six-month mortality was 39% in the pressure-monitoring group and 41% in the imaging-clinical examination group (P=0.60). The median length of stay in the ICU was similar in the two groups (12 days in the pressure-monitoring group and 9 days in the imaging-clinical examination group; P=0.25), although the number of days of brain-specific treatments (e.g., administration of hyperosmolar fluids and the use of hyperventilation) in the ICU was higher in the imaging-clinical examination group than in the pressure-monitoring group (4.8 vs. 3.4, P=0.002). The distribution of serious adverse events was similar in the two groups.
For patients with severe traumatic brain injury, care focused on maintaining monitored intracranial pressure at 20 mm Hg or less was not shown to be superior to care based on imaging and clinical examination. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT01068522.) 11).