Race\ethnicity and outcome after traumatic brain injury at a single, diverse center.

BACKGROUND: Many factors may predict mortality and disability after traumatic brain injury (TBI), including age and injury severity. However, the role of race\ethnicity has typically been studied tangentially or in homogeneous settings. We investigated whether race\ethnicity was associated with medical outcomes at a single, diverse center. METHODS: We retrospectively identified patients with TBI older than 17 years with blunt injuries admitted to a Level I trauma center from 2001 to 2004. Glasgow Outcome Scale (GOS) was used to determine outcome at discharge. We performed multivariable logistic regression on two measures of outcome by dichotomizing Glasgow Outcome Scale scores. RESULTS: We identified 357 patients with TBI from five categories: whites (46.2%), Asians (19.9%), Hispanics (17.9%), blacks (10.9%), and other\unknown (5.0%). Without adjusting for other factors, Asians experienced higher mortality (odds ratio [OR] = 2.25, p = 0.01) compared with whites but not degree of disability. After adjusting for age and Injury Severity Score, a weaker trend remained for higher mortality in Asians (OR = 1.38, p = 0.35), and after excluding cases of assault, the finding was again significant (OR = 2.00, p = 0.04). We also confirmed the recently reported OR of higher mortality among blacks (OR = 1.30). Hispanics seemed to do slightly better at discharge. CONCLUSIONS: The question of whether and how race plays a role in TBI is controversial. At a single, diverse center, we found that mortality is associated with race, age, and Injury Severity Score. Future clinical studies will benefit from detailed genotypic and phenotypic data and should balance larger sample sizes with ethnic diversity.

The role of lung function in brain tissue oxygenation following traumatic brain injury.

OBJECTIVE: Previous studies have demonstrated that periods of low brain tissue oxygen tension (PbtO2) are associated with poor outcome after head trauma but have primarily focused on cerebral and hemodynamic factors as causes of low PbtO2. The purpose of this study was to investigate the influence of lung function on PbtO2 with an oxygen challenge (increase in fraction of inspired oxygen [FiO2] concentration to 1.0). METHODS: This prospective observational cohort study was performed in the neurointensive care unit of the Level 1 trauma center at San Francisco General Hospital. Thirty-seven patients with severe traumatic brain injury (TBI) undergoing brain tissue oxygen monitoring as part of regular care underwent an oxygen challenge, consisting of an increase in FiO2 concentration from baseline to 1.0 for 20 minutes. Partial pressure of arterial oxygen (PaO2), PbtO2, and the ratio of PaO2 to FiO2 (the PF ratio) were determined before and after oxygen challenge. RESULTS: Patients with higher PF ratios achieved greater PbtO2 during oxygen challenge than those with a low PF ratio because they achieved a higher PaO2 after an oxygen challenge. Lung function, specifically the PF ratio, is a major determinant of the maximal PbtO2 attained during an oxygen challenge. CONCLUSIONS: Given that patients with TBI are at risk for pulmonary complications such as pneumonia, severe atelectasis, and adult respiratory distress syndrome, lung function must be considered when interpreting brain tissue oxygenation.

Predictive values of age and the Glasgow Coma Scale in traumatic brain injury patients treated with decompressive craniectomy.

BACKGROUND: The use of decompressive craniectomy (DC) as an aggressive therapy for traumatic brain injury (TBI) has gained renewed interest. While age and the Glasgow Coma Scale (GCS) are frequently correlated with outcome in TBI, their prognostic values after decompressive craniectomy are ill-defined. METHODS: We retrospectively reviewed data from 103 TBI patients treated with DC from 2001 to 2003. Age, preoperative GCS, and injury severity scores were recorded. Outcome at time of discharge was measured with the Glasgow Outcome Scale (GOS). Patients were stratified into the following age groups: < 35, 35-49, 50-64, and > or = 65 years. Spearman's correlation coefficients between age, GCS, and GOS were calculated for the entire population and each age group. FINDINGS: Mortality rates for each age group were 19.2%, 66.7%, 60%, and 80%, respectively. There was a significant negative correlation between age and GOS (r = -0.42, p < 0.0001) and patients < 35 years had significantly better outcomes than patients > or = 35 years (p < 0.0001). The overall correlation between GCS and GOS did not reach significance (r = 0.18,p = 0.076). When stratified by age, there was a significant correlation between GCS and GOS only in patients 35-49 years (r = 0.51, p = 0.011). CONCLUSIONS: This data suggests that in TBI patients treated with DC, age correlates with outcome while the correlation between GCS and outcome is age-dependent.

The role of early follow-up computed tomography imaging in the management of traumatic brain injury patients with intracranial hemorrhage.

BACKGROUND: The purpose of this study was to investigate whether routine follow-up computed tomography (CT) for patients with head injury, in the absence of clinical indications, alters patient management. METHODS: Nonpenetrating head injury patients admitted to San Francisco General Hospital during an 18-month period were reviewed. Patients not surgically treated at presentation and with a routine follow-up head CT within 24 hours were included. Surgical and nonsurgical interventions after repeat CT were assessed. Clinical and imaging parameters were correlated with progressive hemorrhagic injury (PHI) and with delayed development of surgical lesions. RESULTS: PHI was identified in 49 (42%) of 116 patients. None of these patients required a nonoperative intervention in response to the PHI. Six of these patients developed a neurologic change concurrent with routine follow-up imaging and required operative intervention. Thus, no patient underwent an intervention in response to a worsening head CT in the absence of clinical findings. Of the six patients who developed a surgical lesion, two had increased intracranial pressure, one had a change in pupillary examination, three had worsening mental status, and one had change in the motor examination. Univariate risk factors for development of a delayed surgical lesion included 5 to 10 mm of midline shift (p = 0.001), basal cistern effacement (p = 0.01), and higher Marshall score (p = 0.01) on initial CT imaging. CONCLUSIONS: Although PHI is common with head injury, delayed interventions in the absence of clinical indicators are uncommon. Our data suggest that early follow-up CT imaging in the setting of head trauma is not routinely indicated. We suggest that assessment, based on the severity of findings on initial brain imaging and serial clinical examinations, should guide the need for follow-up imaging in the setting of head trauma.

Pupil examination: validity and clinical utility of an automated pupillometer.

Pupillary size and reactivity have long been a critical component of the clinical assessment of patients with neurological disorders. The pupillary examination may provide critical information related to new or worsening intracranial pathology and facilitate prompt intervention to minimize further neuronal damage. With this in mind, intensive care nurses caring for neurologically impaired patients frequently must perform pupillary examinations in concert with assigning a Glasgow Coma Scale score. The purpose of this study was to test the accuracy and reliability of an automated pupillometer compared with the standard manual examination as a preliminary step in assessing the usefulness of automated pupillometry in the critical care setting. Twenty patients in the intensive care units of a teaching hospital were examined by two groups of three examiners using both the manual examination with a penlight or similar light source and a portable automated pupillometer capable of measuring pupil size and reaction. Measurements by a static pupillometer before and after each pupillary examination were used to determine the mean "true" size of the pupil. This study found that the automated pupillometer is more accurate and reliable than the manual examination in measuring pupil size and reactivity. For these reasons, such a device may be a beneficial addition in the clinical assessment of neurologically impaired patients.

Volumetric proton spectroscopic imaging of mild traumatic brain injury.

BACKGROUND AND PURPOSE: Poor clinical outcomes without notable neuroimaging findings after mild traumatic brain injury (MTBI) suggest diffuse tissue damage and altered metabolism not observable with conventional MR imaging and CT. In this study, MTBI-associated metabolic changes were assessed over the entire brain by using volumetric proton MR spectroscopic imaging (MRSI) and the findings related to injury and outcome assessments. METHODS: Fourteen subjects with mild closed head injury (Glasgow Coma Scale [GCS] scores of 13-15) underwent structural MR imaging and proton MRSI at 1.5 T within 1 month of injury. Distributions of N-acetylaspartate (NAA), total creatine (Cr), and total choline (Cho) were mapped over a wide region of the brain, and metabolite ratios were calculated for 25 regions without MR imaging abnormalities. Results were compared with data from 13 control subjects. RESULTS: Significant changes (P <.05) were found for some, but not all, brain regions for the average values from all MTBI subjects, with reduced NAA/Cr, increased Cho/Cr, and reduced NAA/Cho. Global NAA/Cho obtained from the sum of all sampled regions in two subjects was significantly reduced. Metabolite ratios were not significantly correlated with GCS score at admission or Glasgow Outcome Scale (GOS) score at 6 months after injury, although they were weakly correlated with GOS score at discharge. CONCLUSION: These results show evidence of widespread metabolic changes following MTBI in regions that appear normal on diagnostic MR images. Although the association with injury assessment and outcome is weak, this preliminary study demonstrates the applicability of volumetric proton MRSI for evaluating diffuse injury associated with MTBI.

Emergency research: using exception from informed consent, evaluation of community consultations.

BACKGROUND: In 1996, the U.S. Food and Drug Administration approved regulations authorizing an exception from informed consent (EFIC) for research conducted in emergency settings when obtaining prospective informed consent is not possible due to the potential subject's critical illness or injury. The regulations require that investigators conduct community consultation (CC) efforts before initiating a study and require that institutional review boards review the results of CC prior to approving a study. However, little is known about how communities view EFIC research or the CC process. OBJECTIVES: The objective was to assess the views of CC meeting attendees regarding the CC process, their understanding and views of EFIC research relating to the specific research trial under discussion, and their level of trust in physician-investigators. METHODS: Following CC meetings at two study sites (San Francisco and Atlanta) for the Rapid Anticonvulsant Medication Prior to Arrival Trial (RAMPART), an active comparison, randomized trial of prehospital treatment for status epilepticus, the authors administered a pair of surveys to participants. One survey focused on CC experiences (CC survey) and trust in physician-investigators; the second assessed participants' understanding of EFIC and the RAMPART clinical trial design (EFIC survey). RESULTS: A total of 317 individuals participated in one of the two most popular types of CC meetings (group meetings and focus group sessions) at both sites. A total of 189 participants (59%) completed the CC survey and trust questions, and 297 (92%) completed the EFIC survey. Of those who completed the CC survey, 173 of 189 (92%) were very satisfied with the meeting, and 174 of 189 (92%) felt that they learned a lot about research at the meeting. A total of 169 of 189 participants (88%) felt that researchers heard the community's concerns, while only 106 of 189 (56%) said researchers would be willing to make changes to the study based on their concerns. Of those who completed the EFIC survey, 261 of 297 (88%) supported the study, 207 of 297 (70%) said they would agree to participate in the study, and 203 of 297 (68%) reported that they would agree to consent a loved one into the study. On a recently validated scale measuring trust in physician-investigators, participants at both sites seemed to have higher levels of trust in physician-investigators than the validation study population. CONCLUSIONS: Overall, members of these two communities expressed satisfaction with the CC session and had relatively high levels of support for the study and trust in physician-investigators.

Interobserver variability in the assessment of CT imaging features of traumatic brain injury.

The goal of our study was to determine the interobserver variability between observers with different backgrounds and experience when interpreting computed tomography (CT) imaging features of traumatic brain injury (TBI). We retrospectively identified a consecutive series of 50 adult patients admitted at our institution with a suspicion of TBI, and displaying a Glasgow Coma Scale score < or =12. Noncontrast CT (NCT) studies were anonymized and sent to five reviewers with different backgrounds and levels of experience, who independently reviewed each NCT scan. Each reviewer assessed multiple CT imaging features of TBI and assigned every NCT scan a Marshall and a Rotterdam grading score. The interobserver agreement and coefficient of variation were calculated for individual CT imaging features of TBI as well as for the two scores. Our results indicated that the imaging review by both neuroradiologists and neurosurgeons were consistent with each other. The kappa coefficient of agreement for all CT characteristics showed no significant difference in interpretation between the neurosurgeons and neuroradiologists. The average Bland and Altman coefficients of variation for the Marshall and Rotterdam classification systems were 12.7% and 21.9%, respectively, which indicates acceptable agreement among all five reviewers. In conclusion, there is good interobserver reproducibility between neuroradiologists and neurosurgeons in the interpretation of CT imaging features of TBI and calculation of Marshall and Rotterdam scores.

Acute traumatic intraparenchymal hemorrhage: risk factors for progression in the early post-injury period.

OBJECTIVE: To characterize the natural course of traumatic intraparenchymal contusions and hematomas (IPHs) and to identify risk factors for IPH progression in the acute post-injury period. METHODS: A retrospective analysis was performed on a prospective observational database containing 113 head trauma patients exhibiting 229 initially nonoperated acute IPHs. The main outcome variable was radiographic evidence of IPH progression on serially obtained head computed tomographic (CT) scans. Secondary outcomes included the actual amount of IPH growth and later surgical evacuation. Univariate and multivariate analyses (using a generalized estimate equation) were applied to both demographic and initial radiographic features to identify risk factors for IPH progression and surgery. RESULTS: Overall, 10 IPHs (4%) shrank, 133 (58%) remained unchanged, and 86 (38%) grew between the first and second head CT scan. IPH progression was independently associated with the presence of subarachnoid hemorrhage (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.12-2.3), presence of a subdural hematoma (OR, 1.94; 95% CI, 1.1-3.43), and initial size (OR, 1.11; 95% CI, 1.02-1.21, for each cm volume). Size of initial IPH proportionately correlated with the amount of subsequent growth (linear regression, P < 0.001). Worsened Glasgow Coma Score between initial and follow-up head CT scan (OR, 8.6; 95% CI, 1.5-50), IPH growth greater than 5 cm (OR, 7.3; 95% CI, 1.6-34), and effacement of basal cisterns on initial CT scan (OR, 9.0; 95% CI, 1.5-52) were strongly associated with late surgical evacuation. CONCLUSION: A large proportion of IPHs progress in the acute post-injury period. IPHs associated with subarachnoid hemorrhage, a subdural hematoma, or large initial size should be monitored carefully for progression with repeat head CT imaging. Effacement of cisterns on the initial head CT scan was strongly predictive of failure of nonoperative management, thereby leading to surgical evacuation. These findings should be important factors in the understanding and management of IPH.

Acute traumatic intraparenchymal hemorrhage: risk factors for progression in the early post-injury period.

OBJECTIVE: To characterize the natural course of traumatic intraparenchymal contusions and hematomas (IPHs) and to identify risk factors for IPH progression in the acute post-injury period. METHODS: A retrospective analysis was performed on a prospective observational database containing 113 head trauma patients exhibiting 229 initially nonoperated acute IPHs. The main outcome variable was radiographic evidence of IPH progression on serially obtained head computed tomographic (CT) scans. Secondary outcomes included the actual amount of IPH growth and later surgical evacuation. Univariate and multivariate analyses (using a generalized estimate equation) were applied to both demographic and initial radiographic features to identify risk factors for IPH progression and surgery. RESULTS: Overall, 10 IPHs (4%) shrank, 133 (58%) remained unchanged, and 86 (38%) grew between the first and second head CT scan. IPH progression was independently associated with the presence of subarachnoid hemorrhage (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.12-2.3), presence of a subdural hematoma (OR, 1.94; 95% CI, 1.1-3.43), and initial size (OR, 1.11; 95% CI, 1.02-1.21, for each cm volume). Size of initial IPH proportionately correlated with the amount of subsequent growth (linear regression, P < 0.001). Worsened Glasgow Coma Score between initial and follow-up head CT scan (OR, 8.6; 95% CI, 1.5-50), IPH growth greater than 5 cm (OR, 7.3; 95% CI, 1.6-34), and effacement of basal cisterns on initial CT scan (OR, 9.0; 95% CI, 1.5-52) were strongly associated with late surgical evacuation. CONCLUSION: A large proportion of IPHs progress in the acute post-injury period. IPHs associated with subarachnoid hemorrhage, a subdural hematoma, or large initial size should be monitored carefully for progression with repeat head CT imaging. Effacement of cisterns on the initial head CT scan was strongly predictive of failure of nonoperative management, thereby leading to surgical evacuation. These findings should be important factors in the understanding and management of IPH.

Effects of 23.4% sodium chloride solution in reducing intracranial pressure in patients with traumatic brain injury: a preliminary study.

OBJECTIVE: Mannitol is the standard of care for patients with increased intracranial pressure (ICP), but multiple administrations of mannitol risk renal toxicity and fluid accumulation in the brain parenchyma with consequent worsening of cerebral edema. This preliminary study assessed the safety and efficacy of small-volume injections of 23.4% sodium chloride solution for the treatment of intracranial hypertension in patients with traumatic brain injury who became tolerant to mannitol. METHODS: We retrospectively reviewed the charts of 13 adult patients with traumatic brain injury who received mannitol and 23.4% sodium chloride independently for the treatment of intracranial hypertension at San Francisco General Hospital between January and October 2003. Charts were reviewed to determine ICP, cerebral perfusion pressure, mean arterial pressure, serum sodium values, and serum osmolarity before and after treatment with 23.4% sodium chloride and mannitol. Complications were noted. RESULTS: The mean reductions in ICP after treatment were significant for both mannitol (P < 0.001) and hypertonic saline (P < 0.001); there were no significant differences between reductions in ICP when comparing the two agents (P = 0.174). The ICP reduction observed for hypertonic saline was durable, and its mean duration of effect (96 min) was significantly longer than that of mannitol treatment (59 min) (P = 0.016). No complications were associated with treatment with hypertonic saline. CONCLUSION: This study suggests that 23.4% hypertonic saline is a safe and effective treatment for elevated ICP in patients after traumatic brain injury. These results warrant a rigorous evaluation of its efficacy as compared to mannitol in a prospective randomized controlled trial.