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Management of severe head injury: institutional variations in care and effect on outcome.

Bulger EM, Nathens AB, Rivara FP, et al.

Crit Care Med 2002;30(8):1870-6. [abstract]

Reviewed by Jason L. Adler MD, Children's Memorial Hospital, Chicago, IL

Review posted May 18, 2003

I. What is being studied?

Study objective:

The study had three stated objectives:

1. To examine variations in care of patients with severe brain injury in academic trauma centers in the United States.
2. To determine the proportion of patients cared for in conjunction with Brain Trauma Foundation guidelines.
3. To correlate outcome from severe brain injury with level of care received.

Study design

The study was a retrospective observational study conducted at 34 participating university hospitals in the Trauma Benchmarking Project of the University HealthSystem Consortium, a group of 84 university hospitals throughout the United States. Patients eligible for enrollment were 18 years of age or older admitted to a study hospital between May 1, 1998 and December 31, 1998 with multiple trauma consisting of, at a minimum, head injury and a fracture of the tibia, fibula or femur. Exclusion criteria included burn injury, pregnancy, spinal cord injury with paralysis, and patients transferred from another institution > 24 hours after the initial injury. Patients enrolled in the study suffered severe brain injury that was defined as an initial emergency department Glasgow Coma Score (GCS) less than or equal to 8.

The goal was to assess variability in care (including prehospital intubation, neurosurgical consultation, intracranial pressure monitoring, use of osmotic agents, hyperventilation, ventriculostomy, and computed tomography scan utilization) and to determine the influence of aggressiveness of care on outcome. Centers were defined as aggressive or nonaggressive based upon the frequency of ICP monitor placement in patients meeting the guideline criteria of a GCS less than or equal to 8 and an abnormal CT scan of the brain. Centers that placed monitors in >50% of the patients meeting the criteria were defined as aggressive.

Outcomes assessed:

The primary outcome measures were the survival, functional status and discharge disposition of severely brain injured patients stratified on the basis of management strategy.

II. Are the results of the study valid?

1. Are the outcome measures accurate and comprehensive?

Mortality, length of stay and hospital discharge disposition was assessed. The study did not assess long-term functional status which is very important in the head injury population. Functional status at hospital discharge was assessed only grossly using the level of supportive care required. No validated functional status assessment instruments were used. Hypotension on admission was present in 24% of patients. Initial head CT data was available on 156 patients of which 78% had intracranial pathology.

ICP monitors were placed in 105 patients (58%). 79 patients received prehospital intubation (43%). 146 patients (80%) received either prehospital or emergency department intubation. 140 patients (77%) received neurosurgical consultation. 53 patients (29%) received osmotic agents. 25 patients (14%) were treated with hyperventilation. 23 patients (13%) underwent ventriculostomy. Some patients received therapy that is often guided by ICP monitoring, such as hyperventilation or osmotic agent use, even though they did not have an ICP monitor placed. Mortality rate was 37% (68 patients).

Variation in care among the institutions was marked. The median rate for ICP monitors was 33% of patients with a range of 0% to 100%. Stratification for severity demonstrated increased use of ICP monitors among the more severely injured patients, although the variability still persisted with stratification, with a median of 50% monitor use. Variation in the percentage of patients receiving prehospital intubation per center was notable with a median rate of 33% and a range of 0% to 90%. Stratification by severity did not affect the variability in prehospital intubation. A potential explanation for the variability observed in ICP monitoring might be neurosurgical involvement. There were higher rates of neurosurgical consultation than ICP monitoring and less variability. The median rate for neurosurgical consultation was 66% with a range of 66% to 100%. There were higher rates of consultation for more severely injured patients. There was considerable variability in the use of hyperventilation with a median of 0% and a range of 0% to 75% and for osmotic agents with a median of 20% and a range of 0% to 75%.

2. Were the comparison groups similar with respect to important determinants of outcome, other than the one of interest, and were residual differences adjusted for in the analysis?

Among the 34 study hospitals, medical records were obtained on 640 patients of whom 621 had complete data available for analysis. 182 patients had a presenting GCS less than or equal to 8 and were the population analyzed for the study. They were managed at 33 different centers. The mean age was 40 years and 75% were male.

No significant differences were found between the centers classified as aggressive or nonaggressive with respect to age, gender, injury severity score, head abbreviated injury score, or hypotension. These potential confounding variables were controlled for in the analysis using a regression model.

III. What are the results?

1. What are the recommendations?

Of the 33 centers, 2 were excluded because they did not report any patients meeting both guideline criteria for severe head injury. 11 of the remaining 31 centers were classified as aggressive (36%) and 20 (64%) as nonaggressive centers. Of patients with severe head injury, 74 were managed at aggressive centers and 106 at nonaggressive centers (with 2 of the original group missing from the data, perhaps from exclusion of the 2 centers). There were significant differences in the treatment strategies between the aggressive and nonaggressive centers. There were significantly higher rates of ICP monitoring (69% vs. 24%), neurosurgical consultation (91% vs. 69%), use of osmotic agents (49% vs. 16%), ventriculostomy (19% vs. 8.5%) and significantly higher mean number of head scans per patient (3.4 vs. 1.9) at aggressive versus nonaggressive centers. There was no significant difference in pulmonary arterial catheter (perhaps a marker for intensive care utilization) use or prehospital intubation between the two types of centers.

Overall mortality was 27% (20 of 74) at aggressive centers vs. 45% (48 of 106) at nonaggressive centers with a p=0.01. This amounts to an absolute relative risk of 0.18 (95% CI 0.04 to 0.32) and a relative risk reduction of 40% (95% CI 10% to 60%) for treatment at aggressive centers versus nonaggressive centers. Using linear regression to control for multiple variables, management at an aggressive center was associated with a decrease in LOS of 6 days, although this was not statistically significant. There was no significant difference in functional status of survivors at the time of discharge comparing data from aggressive vs. nonaggressive centers. There was a nonsignificant trend toward higher rates of discharge to rehabilitation facilities by nonaggressive hospitals as opposed to skilled nursing facilities or acute care transfers. The data support the aggressive management of patients with severe head injury.

IV. Will the results help me in caring for my patients?

1. How will the recommendations help you?

The data presented in this paper supports prior findings that considerable variability in care among centers exists with respect to the management of head-injured patients (1). This variability appears to influence mortality. Aggressive use of ICP monitoring was associated with decreased mortality. One cannot conclude from this study that aggressive use of ICP monitoring is clearly indicated. Functional status was only measured grossly by evaluating amount of support required at discharge. The study was not randomized and one cannot ensure that severity of brain injury was adequately controlled for. However, this study does give some evidence that following the evidence-based guidelines for the management of head-injured patients by the Brain Trauma Foundation may lead to improved outcomes (2). These guidelines were last amended in 2000 to include a recommendation for prehospital intubation for the severe head injury due to decreased mortality (3). Although ICP monitoring for the management of patients with head injury has been controversial, aggressive lowering of ICP in head-injured patients had been associated with improved outcome in some studies, and ICP monitoring has been associated with improved survival (4). Other studies have shown that cerebral perfusion directed management has been associated with decreased long-term morbidity (5). The current indications for ICP monitoring include all patients with a GCS less than or equal to 8 and an abnormal CT scan of the head, or a patient with a GCS less than or equal to 8 and a normal CT scan but two or more of the following risk factors: age > 40 years, unilateral or bilateral motor posturing, or systolic BP less than 90 mmHg (6). This study focused only on the first criteria for simplicity, but this should not necessarily impair the generalizability of the findings. It was found that only 11 of 31 centers (35%) placed a monitor in > 50% of patients meeting these criteria. There was a trend toward higher trauma volume in the aggressive centers that did not reach statistical significance.

This study highlights the disconnect between the publication of guidelines for severe head injury and their implementation into management strategies, even when their implementation had been associated with decreased mortality. The findings of this study are consistent with recent data that has been published supporting the use of aggressive management in patients with severe brain injury in terms of improved survival, which includes among other things early intubation and ICP monitoring. As such, this paper provides indirect support of a multi-specialty approach to the management of the severely brain injured patient. One of the limitations of this study is that it does not discuss how the ICP monitoring was used in the treatment of the patients. While controversy remains whether goal-directed therapy targeting ICP or cerebral perfusion is a better strategy, neither are possible without ICP monitoring devices. The study implies that the ICP monitoring devices were somehow used by the physicians managing the patients with severe brain injury and that some goal-directed management strategy is better than blindly managing patients. Whether decreased mortality is beneficial to patients or society when the functional status of the patient is partly or severely impaired in the overwhelming majority of patients is beyond the scope of this discussion, but is nonetheless an important consideration, and may be impacting patient management decisions.

A final point is the generalizability of and adult study the pediatric population. In some respects, the pathophysiology of traumatic brain injury is similar in pediatric patients and adults, although certain differences do exist. Nevertheless, this study does provide useful insight into ways in which to manage traumatic brain injury.

References

1. Vukic M, Negovetic L, Kovac D, et al: The effect of implementation of guidelines for the management of severe head injury on patient treatment and outcome. Acta Neurochir 1999; 141:1203-1208 [abstract]
2. Guidelines for the management of severe head injury. Brain Trauma Foundation, American Association of Neurological Surgeons, Joint Section on Neurotrauma and Critical Care. J Neurotrauma 1996; 13:641-734 [abstract]
3. The Brain Trauma Foundation: The American Association of Neurological Surgeons. The Joint Section on Neurotrauma and Critical Care. Resuscitation of blood pressure and oxygenation. J neurotrauma 2000; 17:471-478 [abstract]
4. Eddy VA, Vitsky JL, Rutherford EJ, et al: Aggressive use of ICP monitoring is safe and alters patient care. Am Surg 1995; 61:24-29 [abstract]
5. Lane PL, Skoretz TG, Doig G, et al: Intracranial pressure monitoring and outcomes after traumatic brain injury. Can J Surg 2000; 43:442-448 [abstract]
6. The Brain Trauma Foundation: The American Association of Neurological Surgeons. The Joint Section on Neurotrauma and Critical Care. Indications for intracranial pressure monitoring. J Neurotrauma 2000; 17:479-491 [abstract]

 

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