Initial head computed tomographic scan characteristics have a linear relationship with initial intracranial pressure after trauma

BACKGROUND: Despite current recommendations by the Brain Trauma Foundation regarding the placement of intracranial pressure (ICP) monitoring devices, advances in computed tomographic (CT) scan technology have led to the suggestion that increased ICP may be predicted by findings on admission head CT scan and that patients without such findings do not require such monitoring. A linear relationship exists between characteristics of admission head CT scan and initial ICP level, allowing for selective placement of ICP monitoring devices. METHODS: From 1997 to 2001, a retrospective review of patients admitted with a Glasgow Coma Scale (GCS) score < 8 and head CT scan who underwent ventriculostomy placement at our institution, was conducted. Patients undergoing craniotomy with evacuation of mass lesions before ventriculostomy placement were excluded. Age, sex, mechanism of injury, anoxia, osmotic treatment, presence of drugs/alcohol, initial mean arterial pressure, initial GCS score, and initial ICP were recorded. Initial head CT scans were reviewed independently by two neuroradiologists who were blinded to ICP measurements, neurosurgical treatment, patient outcome, and each other's interpretation. Initial CT scans were evaluated and scored on a 1 (normal) to 3 (abnormal) scale with respect to ventricle size, basilar cistern size, sulci size, degree of transfalcine herniation, and gray/white matter differentiation. Initial ICP readings and CT scan findings were compared to determine whether a significant linear relationship existed between the above CT scan findings and ICPs. Logistic and univariate linear regression were used to compare averaged radiologist score versus dichotomized ICP at baseline. RESULTS: Initial head CT scan characteristics show a linear relationship to baseline ICPs. These findings are associative, but are not uniformly predictive. CONCLUSION: Therefore, the current Brain Trauma Foundation recommendation of ICP monitoring in those patients presenting with a GCS score < 8 with an abnormal CT scan or a normal CT scan with age > 40 years, systolic blood pressure < 90 mm Hg, or exhibiting posturing should be followed.     

ICP threshold in CPP management of severe head injury patients

BACKGROUND: Elevated intracranial pressure (ICP) is significantly associated with high mortality rate in severe head injury (SHI) patients. However, there is no absolute agreement regarding the level at which ICP must be treated. The objective of this study was to compare the outcomes of severe head injury patients treated by setting the ICP threshold at >or=20 mm Hg or >or=25 mm Hg. METHODS: Treatment protocol in this study consisted of therapeutic maneuvers designed to maximize cerebral profusion pressure (CPP) and control ICP. Twenty-seven patients with severe head injury and intracranial hypertension (ICP >or=20 mm Hg) were enrolled and fourteen cases were allocated to the group of ICP threshold >or=25 mm Hg. Six-month clinical outcomes were evaluated using the Glasgow Outcome Score (GOS). RESULTS: There were no statistically significant differences in clinical parameters between the groups. Logistic regression identified the presence of basal cisterns on the initial computed tomography (CT) scan as a significant predictor of good outcome. ICP threshold did not influence outcome. CONCLUSIONS: This study supported a recommended ICP threshold of 20 to 25 mm Hg in SHI management. However, in cases with an absence of basal cisterns on initial CT scan, the probability of good outcome may be higher using an ICP threshold of >or=20 mm Hg.     

Diffuse Axonal Injury (DAI) is not Associated with Elevated Intracranial Pressure (ICP)

Summary Objective. Traditionally, intracranial pressure (ICP) monitoring has been utilized in all patients with severe head injury (Glasgow coma score of 3–8). Ventriculostomy placement, however, does carry a 4 to 10 percent complication rate consisting mostly of hematoma and infection. The authors propose that a subgroup of patients presenting with severe head trauma and diffuse axonal injury without associated mass lesion, do not need ICP monitoring. Additionally, the monitoring data from ICP, MAP, and CPP for a comparison severe head injury group, and subgroups of DAI would be presented. Materials and methods. Thirty-six patients sustaining blunt head trauma and fitting our strict clinical and radiographic diagnosis of DAI were enrolled in our study. Inclusion criteria were severe head injury patients who did not regain consciousness after the initial impact, and whose CT scan demonstrated characteristic punctate hemorrhages of <10 mm diameter at the greywhite junction, basal ganglia, corpus callosum, upper brainstem, or a combination of the above. Patients with significant mass lesions and documented anoxia were excluded. Their intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were compared to a control group of 36 consecutive patients with severe non-penetrating non-operative head injury, using the Analysis for Variance method. Results. Eighteen (50.0%), six (16.7%), and twelve (33.3%) patients had types I, II, and III DAI, respectively. The admission Glasgow Coma Score (GCS) was higher for types I and II than for type III DAI. ICP was monitored from 23 to 165 hours, with a mean ICP for 36 patients of 11.70 mmHg (SEM=75) and a range from 4.3 to 17.3 mmHg. Of all ICP recordings, of which 89.7% (2421/2698) were ≤20 mmHg. Average mean arterial pressure (MAP) was 96.08 mmHg (SEM=1.69), and 94.6% (2038/2154) of all MAP readings were greater than 80 mmHg. Average cerebral perfusion pressure (CPP) was 85.16 mmHg (SEM=1.68), and 90.1% (1941/2154) of all CPP readings were greater than 70 mmHg. This is compared to the control group mean ICP, MAP, and CPP of 16.84 mmHg (p=0.000021), 92.80 mmHg (p=0.18), and 76.49 mmHg (p=0.0012). No treatment for sustained elevated ICP>20 mmHg was needed for DAI patients except in two; one with extensive intraventricular and subarachnoid hemorrhage who developed communicating hydrocephalus, and another with ventriculitis requiring intrathecal and intravenous antibiotic treatments. Two complications, one from a catheter tract hematoma, and another with Staph epidermidis ventriculitis, were encountered. All patients, except type III DAI, generally demonstrated marked clinical improvement with time. The outcome, as measured by Glasgow Coma Score (GCS) and Glasgow Outcome Score (GOS) was similarly better with types I and II than type III DAI. Conclusion. The authors conclude that ICP elevation in DAI patients without associated mass lesions is not as prevalent as other severe head injured patients, therefore ICP monitoring may not be as critical. The presence of an ICP monitoring device may contribute to increased morbidity. Of key importance, however, is an accurate clinical history and interpretation of the CT scan.     

Progressive hemorrhage after head trauma: predictors and consequences of the evolving injury.

OBJECT: Progressive intracranial hemorrhage after head injury is often observed on serial computerized tomography (CT) scans but its significance is uncertain. In this study, patients in whom two CT scans were obtained within 24 hours of injury were analyzed to determine the incidence, risk factors, and clinical significance of progressive hemorrhagic injury (PHI). METHODS: The diagnosis of PHI was determined by comparing the first and second CT scans and was categorized as epidural hematoma (EDH), subdural hematoma (SDH), intraparenchymal contusion or hematoma (IPCH), or subarachnoid hemorrhage (SAH). Potential risk factors, the daily mean intracranial pressure (ICP), and cerebral perfusion pressure were analyzed. In a cohort of 142 patients (mean age 34 +/- 14 years; median Glasgow Coma Scale score of 8, range 3-15; male/female ratio 4.3: 1), the mean time from injury to first CT scan was 2 +/- 1.6 hours and between first and second CT scans was 6.9 +/- 3.6 hours. A PHI was found in 42.3% of patients overall and in 48.6% of patients who underwent scanning within 2 hours of injury. Of the 60 patients with PHI, 87% underwent their first CT scan within 2 hours of injury and in only one with PHI was the first CT scan obtained more than 6 hours postinjury. The likelihood of PHI for a given lesion was 51% for IPCH, 22% for EDH, 17% for SAH, and 11% for SDH. Of the 46 patients who underwent craniotomy for hematoma evacuation, 24% did so after the second CT scan because of findings of PHI. Logistic regression was used to identify male sex (p = 0.01), older age (p = 0.01), time from injury to first CT scan (p = 0.02), and initial partial thromboplastin time (PTT) (p = 0.02) as the best predictors of PHI. The percentage of patients with mean daily ICP greater than 20 mm Hg was higher in those with PHI compared with those without PHI. The 6-month postinjury outcome was similar in the two patient groups. CONCLUSIONS: Early progressive hemorrhage occurs in almost 50% of head-injured patients who undergo CT scanning within 2 hours of injury, it occurs most frequently in cerebral contusions, and it is associated with ICP elevations. Male sex, older age, time from injury to first CT scan, and PTT appear to be key determinants of PHI. Early repeated CT scanning is indicated in patients with nonsurgically treated hemorrhage revealed on the first CT scan.     

Reverse Trendelenburg position reduces intracranial pressure during craniotomy.

Cerebral swelling and herniation pose serious surgical obstacles during craniotomy for space-occupying lesions. Positioning patients head-up has been shown previously to reduce intracranial pressure (ICP) in neurotraumatized patients, but has not been investigated during intracranial surgery. The current study examined the effects of 10-deg reverse Trendelenburg position (RTP) on ICP and cerebral perfusion pressure (CPP). Forty adult patients subjected to craniotomy for supratentorial tumors were given standardized propofol-fentanyl-cisatracurium general anesthesia and were moderately hyperventilated. In 26 of 40 patients with expected poor clinical outcome, an additional catheter was placed in the internal jugular bulb to determine internal jugular bulb pressure (JBP). ICP was determined by subdural measurement using a 22-gauge needle advanced through the dura after removal of the bone flap. ICP was referenced to the level of the dural incision. ICP, mean arterial blood pressure, and CPP were compared with repeat measurements 1 minute after RTP. The tension of the dura was graded qualitatively by the surgeon by digital palpation and was compared to post-RTP. ICP decreased from 9.5 mm Hg to 6.0 mm Hg ( P <.001; all values are median) within 1 minute after 10-deg RTP. Mean arterial blood pressure decreased from 82.0 mm Hg to 78.5 mm Hg ( P <.001). CPP was unchanged (70.5 mm Hg versus 71 mm Hg after RTP), whereas JBP decreased from 8 mm Hg to 4 mm Hg ( P <.001). High initial ICP was correlated to the greatest magnitude of decrease in ICP. No significant correlation was found between change in ICP and change in JBP. Intracranial pressure after RTP resulted in decreased tension of the dura. RTP appears to be an effective means of reducing ICP during craniotomy, thereby reducing the risk of cerebral herniation. CPP is not affected. Studies over longer periods of time are warranted, however.     

Reduced mortality rate in patients with severe traumatic brain injury treated with brain tissue oxygen monitoring

OBJECT: An intracranial pressure (ICP) monitor, from which cerebral perfusion pressure (CPP) is estimated, is recommended in the care of severe traumatic brain injury (TBI). Nevertheless, optimal ICP and CPP management may not always prevent cerebral ischemia, which adversely influences patient outcome. The authors therefore determined whether the addition of a brain tissue oxygen tension (PO2) monitor in the treatment of TBI was associated with an improved patient outcome. METHODS: Patients with severe TBI (Glasgow Coma Scale [GCS] score < 8) who had been admitted to a Level I trauma center were evaluated as part of a prospective observational database. Patients treated with ICP and brain tissue PO2 monitoring were compared with historical controls matched for age, pathological features, admission GCS score, and Injury Severity Score who had undergone ICP monitoring alone. Therapy in both patient groups was aimed at maintaining an ICP less than 20 mm Hg and a CPP greater than 60 mm Hg. Among patients whose brain tissue PO2 was monitored, oxygenation was maintained at levels greater than 25 mm Hg. Twenty-five patients with a mean age of 44 +/- 14 years were treated using an ICP monitor alone. Twenty-eight patients with a mean age of 38 +/- 18 years underwent brain tissue PO2-directed care. The mean daily ICP and CPP levels were similar in each group. The mortality rate in patients treated using conventional ICP and CPP management was 44%. Patients who also underwent brain tissue PO2 monitoring had a significantly reduced mortality rate of 25% (p < 0.05). CONCLUSIONS: The use of both ICP and brain tissue PO2 monitors and therapy directed at brain tissue PO2 is associated with reduced patient death following severe TBI.     

Intracranial hypertension and cerebral perfusion pressure: influence on neurological deterioration and outcome in severe head injury. The Executive Committee of the International Selfotel Trial

OBJECT: Recently, a renewed emphasis has been placed on managing severe head injury by elevating cerebral perfusion pressure (CPP), which is defined as the mean arterial pressure minus the intracranial pressure (ICP). Some authors have suggested that CPP is more important in influencing outcome than is intracranial hypertension, a hypothesis that this study was designed to investigate. METHODS: The authors examined the relative contribution of these two parameters to outcome in a series of 427 patients prospectively studied in an international, multicenter, randomized, double-blind trial of the N-methyl-D-aspartate antagonist Selfotel. Mortality rates rose from 9.6% in 292 patients who had no clinically defined episodes of neurological deterioration to 56.4% in 117 patients who suffered one or more of these episodes; 18 patients were lost to follow up. Correspondingly, favorable outcome, defined as good or moderate on the Glasgow Outcome Scale at 6 months, fell from 67.8% in patients without neurological deterioration to 29.1% in those with neurological deterioration. In patients who had clinical evidence of neurological deterioration, the relative influence of ICP and CPP on outcome was assessed. The most powerful predictor of neurological worsening was the presence of intracranial hypertension (ICP > or = 20 mm Hg) either initially or during neurological deterioration. There was no correlation with the CPP as long as the CPP was greater than 60 mm Hg. CONCLUSIONS: Treatment protocols for the management of severe head injury should emphasize the immediate reduction of raised ICP to less than 20 mm Hg if possible. A CPP greater than 60 mm Hg appears to have little influence on the outcome of patients with severe head injury.     

Management morbidity and mortality of poor-grade aneurysm patients

Preliminary experience with the occasional good survival of patients in Hunt and Hess Grade IV or V with aneurysmal subarachnoid hemorrhage (SAH) led to a prospective management protocol employed during a 2 1/2-year period. The protocol utilized computerized tomography (CT) scanning to diagnose SAH and to obtain evidence for irreversible brain destruction, consisting of massive cerebral infarction with midline shift or dominant basal ganglia or brain-stem hematoma. These patients, along with those who exhibited poor or absent intracranial filling on CT or angiography, were excluded from active treatment and given supportive care only. All other patients had immediate ventriculostomy placement and, if intracranial pressure (ICP) was controllable (less than or equal to 30 cm H2O without an intracranial clot or less than or equal to 50 cm H2O in the presence of a clot), went on to have craniotomy for aneurysm clipping. Aggressive postoperative hypertensive, hypervolemic, hemodilutional therapy was subsequently employed. Of 54 patients with poor-grade aneurysms, ventriculostomy was placed in 47 (87.0%) and yielded high ICP's in the overwhelming majority, with the mean ICP being 40.2 cm H2O. Nineteen poor-grade aneurysm patients received no surgical treatment and survived a mean of 31.8 hours with 100% mortality. Thirty-five patients underwent placement of a ventriculostomy, craniotomy for aneurysm clipping and intracranial clot evacuation, and postoperative hypertensive, hypervolemic, hemodilutional therapy. The outcome at 3 months of the 35 patients who were selected for active treatment was good in 19 (54.3%), fair in four (11.4%), poor in four (11.4%), and death in eight (22.9%). It is concluded that poor-grade aneurysm patients usually present with intracranial hypertension, even those without an intracranial clot. Based on radiographic rather than neurological criteria, a portion of these patients can be selected for active and successful treatment. Increased ICP can be present without ventriculomegaly, and immediate ventriculostomy should be performed. As long as ICP is controllable, craniotomy and postoperative intensive care can effect a favorable outcome in a significant percentage of these patients.     

Acute subdural hematoma: morbidity, mortality, and operative timing

Traumatic acute subdural hematoma remains one of the most lethal of all head injuries. Since 1981, it has been strongly held that the critical factor in overall outcome from acute subdural hematoma is timing of operative intervention for clot removal; those operated on within 4 hours of injury may have mortality rates as low as 30% with functional survival rates as high as 65%. Data were reviewed for 1150 severely head-injured patients (Glasgow Coma Scale (GCS) scores 3 to 7) treated at a Level 1 trauma center between 1982 and 1987; 101 of these patients had acute subdural hematoma. Standard treatment protocol included aggressive prehospital resuscitation measures, rapid operative intervention, and aggressive postoperative control of intracranial pressure (ICP). The overall mortality rate was 66%, and 19% had functional recovery. The following variables statistically correlated (p less than 0.05) with outcome; motorcycle accident as a mechanism of injury, age over 65 years, admission GCS score of 3 or 4, and postoperative ICP greater than 45 mm Hg. The time from injury to operative evacuation of the acute subdural hematoma in regard to outcome morbidity and mortality was not statistically significant even when examined at hourly intervals although there were trends indicating that earlier surgery improved outcome. The findings of this study support the pathophysiological evidence that, in acute subdural hematoma, the extent of primary underlying brain injury is more important than the subdural clot itself in dictating outcome; therefore, the ability to control ICP is more critical to outcome than the absolute timing of subdural blood removal.     

Relationship between intracranial pressure and other clinical variables in patients with aneurysmal subarachnoid hemorrhage

OBJECT: Increased intracranial pressure (ICP) is well known to affect adversely patients with head injury. In contrast, the variables associated with ICP following aneurysmal subarachnoid hemorrhage (SAH) and their impact on outcome have been less intensely studied. METHODS: In this retrospective study the authors reviewed a prospective observational database cataloging the treatment details in 433 patients with SAH who had undergone surgical occlusion of an aneurysm as well as ICP monitoring. All 433 patients underwent postoperative ICP monitoring, whereas only 146 (33.7%) underwent both pre- and postoperative ICP monitoring. The mean maximal ICP was 24.9 +/- 17.3 mm Hg (mean +/- standard deviation). During their hospital stay, 234 patients (54%) had elevated ICP (> 20 mm Hg), including 136 of those (48.7%) with a good clinical grade (Hunt and Hess Grades I-III) and 98 (63.6%) of the 154 patients with a poor grade (Hunt and Hess Grades IV and V) on admission. An increased mean maximal ICP was associated with several admission variables: worse Hunt and Hess clinical grade (p < 0.0001), a lower Glasgow Coma Scale (GSC) motor score (p < 0.0001); worse SAH grade based on results of computerized tomography studies (p < 0.0001); intracerebral hemorrhage (p = 0.024); severity of intraventricular hemorrhage (p < 0.0001); and rebleeding (p = 0.0048). Both intraoperative cerebral swelling (p = 0.0017) and postoperative GCS score (p < 0.0001) were significantly associated with a raised ICP. Variables such as patient age, aneurysm size, symptomatic vasospasm, intraoperative aneurysm rupture, and secondary cerebral insults such as hypoxia were not associated with raised ICP. Increased ICP adversely affected outcome: 71.9% of patients with normal ICP demonstrated favorable 6-month outcomes postoperatively, whereas 63.5% of patients with ICP between 20 and 50 mm Hg and 33.3% with ICP greater than 50 mm Hg demonstrated favorable outcomes. Among 21 patients whose raised ICP did not respond to mannitol therapy, all experienced a poor outcome and 95.2% died. Among 145 patients whose elevated ICP responded to mannitol, 66.9% had a favorable outcome and only 20.7% were dead 6 months after surgery (p < 0.0001). According to results of multivariate analysis, however, ICP was not an independent outcome predictor (odds ratio 1.26, 95% confidence interval 0.28-5.68). CONCLUSIONS: Increased ICP is common after SAH, even in patients with a good clinical grade. Elevated ICP post-SAH is associated with a worse patient outcome, particularly if ICP does not respond to treatment. This association, however, may depend more on the overall severity of the SAH than on ICP alone.     

Glial fibrillary acidic protein in serum after traumatic brain injury and multiple trauma

BACKGROUND: This study aimed to determine whether glial fibrillary acidic protein (GFAP) is released after traumatic brain injury (TBI), whether GFAP is related to brain injury severity and outcome after TBI, and whether GFAP is released after multiple trauma without TBI. METHODS: This prospective study enrolled 114 patients who had TBI with or without multiple trauma (n = 101) or multiple trauma without TBI (n = 13), as verified by computerized tomography. Daily GFAP measurement began at admission (<12 hours after trauma) and continued for the duration of intensive care (1-22 days). Documentation included categorization of computerized tomography according to Marshall classification, based on daily highest intracranial pressure (ICP), lowest cerebral perfusion pressure (CPP), lowest mean arterial pressure (MAP), and 3-month Glasgow Outcome Score (GOS). RESULTS: The GFAP concentration was lower for diffuse injury 2 than for diffuse injury 4 (p < 0.0005) or nonevacuated mass lesions larger than than 25 mL (p < 0.005), lower for a ICP less than 25 mm Hg than for a ICP of 25 mm Hg or more, lower for a CPP of 60 mm Hg or more than for a CPP of 60 mm Hg or less, lower for a MAP of 60 mm Hg or more than for a MAP less than 60 mm Hg (all p < 0.0005), and lower for a GOS of 1 or 2 than for a GOS of 3, 4 (p < 0.05), or 5 (p < 0.0005). After TBI, GFAP was higher in nonsurvivors (n = 39) than in survivors (n = 62) (p < 0.005). After multiple trauma without TBI, GFAP remained normal. CONCLUSIONS: The findings showed that GFAP is released after TBI, that GFAP is related to brain injury severity and outcome after TBI, and that GFAP is not released after multiple trauma without brain injury.     

Optimal reverse trendelenburg position in patients undergoing craniotomy for cerebral tumors

OBJECT: To the authors' knowledge, repeated measurements of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and the degree of dural tension during different positions on the operating table (reverse Trendelenburg position [rTp]) have not been studied in patients undergoing craniotomy. METHODS: In the present study 53 patients with supratentorial cerebral tumors who underwent craniotomy in the supine position were included. Subdural ICP, mean arterial blood pressure (MABP), CPP, and jugular bulb (JB) pressure were recorded, and the degree of dural tension was analyzed while patients were in the neutral operating position and at 5, 10, and 15 degrees rTp. The optimal operating position was defined as the one at which subdural ICP was as low as possible, and CPP was greater than or equal to 60 mm Hg or as high as possible. Subdural ICP, MABP, and JB pressure decreased significantly after each 5 degrres change in rTp compared with the preceding position. Dural tension decreased significantly up to 10 degrees rTp, but was unchanged at 15 degrees rTp. At 5 degrees rTp CPP remained unchanged, but it decreased significantly during 10 and 15 degrees rTp. The optimal position in the majority of patients was determined to be 15 degrees rTp. CONCLUSIONS: Before opening the dura mater for craniotomy, repeated measurements of ICP and CPP, in the neutral position and at 5, 10, and 15 degrees rTp, provide valuable information regarding the optimal level of ICP and CPP.     

Acute epidural hematoma: an analysis of factors influencing the outcome of patients undergoing surgery in coma

Mortality due to epidural hematoma is virtually restricted to patients who undergo surgery for that condition while in coma. The authors have analyzed the factors influencing the outcome of 64 patients who underwent epidural hematoma evacuation while in coma. These patients represented 41% of the 156 patients operated on for epidural hematoma at their centers after the introduction of computerized tomography (CT). Eighteen patients (28.1%) died, two (3.1%) became severely disabled, and 44 (68.8%) made a functional recovery. The mortality rate for the entire series was 12%, significantly lower than the 30% rate observed when only angiographic studies were available. A significant correlation was found between the final result and the mechanism of injury, the interval between trauma and surgery, the motor score at operation, the hematoma CT density (homogeneous vs. heterogeneous), and the hematoma volume. The patient's age, the course of consciousness before operation (whether there was a lucid interval), and the clot location did not correlate with the final outcome. The mortality rate was significantly higher in patients operated on within 6 hours or between 6 and 12 hours after injury than in those undergoing surgery 12 to 48 hours after injury. Compared with the patients operated on later, the patients undergoing surgery in the early period were, on the average, older and had more rapidly developing symptoms, more pupillary changes, lower motor scores at surgery, larger hematomas, a higher incidence of mixed CT density clots, more severe associated intracranial lesions, and higher postoperative intracranial pressure (ICP). The mechanism of trauma seems to influence the course of consciousness before and after surgery. Passengers injured in traffic accidents had a lower incidence of a lucid interval and longer postoperative coma than patients with low-speed trauma, suggesting more frequent association of diffuse white matter-shearing injury. The duration of postoperative coma correlated with the morbidity rate in survivors. Forty-eight patients (75%) had one or more associated intracranial lesions, and 70% of these required treatment for elevation of ICP after hematoma evacuation. An ICP of over 35 mm Hg strongly correlated with poor outcome; administration of high-dose barbiturates was the only effective means for lowering ICP in nine of 15 patients who developed severe intracranial hypertension after surgery. This study attempts to identify patients at greater risk for presenting postoperative complications and to define a strategy for control CT scanning and ICP monitoring.     

Cerebral cortical oxygenation: a pilot study

BACKGROUND: Cerebral hypoxia (cerebral cortical oxygenation [Pbro2] < 20 mm Hg) monitored by direct measurement has been shown in animal and small clinical studies to be associated with poor outcome. We present our preliminary results observing Pbro2 in patients with traumatic brain injury (TBI). METHODS: A prospective observational cohort study was performed. Institutional review board approval was obtained. All patients with TBI who required measurement of intracranial pressure (ICP), cerebral perfusion pressure (CPP), and Pbro2 because of a Glasgow Coma Scale score < 8 were enrolled. Data sets (ICP, CPP, Pbro2, positive end-expiratory pressure (PEEP), Pao2, and Paco2) were recorded during routine manipulation. Episodes of cerebral hypoxia were compared with episodes without. Results are displayed as mean +/- SEM; t test, chi2, and Fisher's exact test were used to answer questions of interest. RESULTS: One hundred eighty-one data sets were abstracted from 20 patients. Thirty-five episodes of regional cerebral hypoxia were identified in 14 patients. Compared with episodes of acceptable cerebral oxygenation, episodes of cerebral hypoxia were noted to be associated with a significantly lower mean Pao2 (144 +/- 14 vs. 165 +/- 8; p < 0.01) and higher mean PEEP (8.8 +/- 0.7 vs. 7.1 +/- 0.3; p < 0.01). Mean ICP and CPP measurements were similar between groups. In a univariate analysis, cerebral hypoxic episodes were associated with Pao2 < or = 100 mm Hg (p < 0.01) and PEEP > 5 cm H2O (p < 0.01), but not ICP > 20 mm Hg, CPP < or = 65 mm Hg, or Pac2 < or = 35 mm Hg. CONCLUSION: Cerebral oxymetry is confirmed safe in the patient with multiple injuries with TBI. Occult cerebral hypoxia is present in the traumatic brain injured patient despite normal traditional measurements of cerebral perfusion. Further research is necessary to determine whether management protocols aimed at the prevention of cerebral cortical hypoxia will affect outcome.     

Pressure reactivity as a guide in the treatment of cerebral perfusion pressure in patients with brain trauma

OBJECT: The aim of this study was to compare the effects of two different treatment protocols on physiological characteristics and outcome in patients with brain trauma. One protocol was primarily oriented toward reducing intracranial pressure (ICP), and the other primarily on maintaining cerebral perfusion pressure (CPP). METHODS: A series of 67 patients in Uppsala were treated according to a protocol aimed at keeping ICP less than 20 mm Hg and, as a secondary target, CPP at approximately 60 mm Hg. Another series of 64 patients in Edinburgh were treated according to a protocol aimed primarily at maintaining CPP greater than 70 mm Hg and, secondarily, ICP less than 25 mm Hg for the first 24 hours and 30 mm Hg subsequently. The ICP and CPP insults were assessed as the percentage of monitoring time that ICP was greater than or equal to 20 mm Hg and CPP less than 60 mm Hg, respectively. Pressure reactivity in each patient was assessed based on the slope of the regression line relating mean arterial blood pressure (MABP) to ICP. Outcome was analyzed at 6 months according to the Glasgow Outcome Scale (GOS). The prognostic value of secondary insults and pressure reactivity was determined using linear methods and a neural network. In patients treated according to the CPP-oriented protocol, even short durations of CPP insults were strong predictors of death. In patients treated according to the ICP-oriented protocol, even long durations of CPP insult-mostly in the range of 50 to 60 mm Hg--were significant predictors of favorable outcome (GOS Score 4 or 5). Among those who had undergone ICP-oriented treatment, pressure-passive patients (MABP/ICP slope > or = 0.13) had a better outcome. Among those who had undergone CPP-oriented treatment, the more pressure-active (MABP/ICP slope < 0.13) patients had a better outcome. CONCLUSION: Based on data from this study, the authors concluded that ICP-oriented therapy should be used in patients whose slope of the MABP/ICP regression line is at least 0.13, that is, in pressure-passive patients. If the slope is less than 0.13, then hypertensive CPP therapy is likely to produce a better outcome.     

Computed tomographic brain density measurement as a predictor of elevated intracranial pressure in blunt head trauma

There are no independent computed tomography (CT) findings predictive of elevated intracranial pressure (ICP). The purpose of this study was to evaluate brain density measurement on CT as a predictor of elevated ICP or decreased cerebral perfusion pressure (CPP). A prospectively collected database of patients with acute traumatic brain injury was used to identify patients who had a brain CT followed within 2 hours by ICP measurement. Blinded reviewers measured mean density in Hounsfield Units (HU) within a 100-mm2 elliptical region at four standardized positions. Brain density measurement was compared for patients with an ICP of 20 or greater versus less than 20 mm Hg and CPP of 70 or greater versus less than 70 mm Hg. During a 2-year period, 47 patients had ICP monitoring after brain CT. Average age was 40 +/- 18 years old; 93.6 per cent were male; mean Injury Severity Score was 25 +/- 10; and Glasgow Coma Scale was 6 +/- 4. There was no difference in brain density measurement for observer 1, ICP less than 20 (26.3 HU) versus ICP 20 or greater (27.4 HU, P = 0.545) or for CPP less than 70 (27.1 HU) versus CPP 70 or greater (26.2, P = 0.624). Similarly, there was no difference for observer 2, ICP less than 20 (26.8 HU) versus ICP 20 or greater (27.4, P = 0.753) and CPP less than 70 (27.6 HU) versus CPP 70 or greater (26.2, P = 0.436). CT-measured brain density does not correlate with elevated ICP or depressed CPP and cannot predict patients with traumatic brain injury who would benefit from invasive ICP monitoring.     

Effects of dihydroergotamine on intracranial pressure, cerebral blood flow, and cerebral metabolism in patients undergoing craniotomy for brain tumors.

In a search for a nonsurgical intervention to control intracranial hypertension during craniotomy, the authors studied the effects of dihydroergotamine on mean arterial blood pressure (MABP), intracranial pressure (ICP), cerebral perfusion pressure (CPP), cerebral blood flow (CBF), and cerebral metabolism in patients who underwent craniotomy for supratentorial brain tumors. Twenty patients were randomized to receive either dihydroergotamine 0.25 mg intravenously or placebo as a bolus dose during craniotomy. Anesthesia was induced with thiopental/fentanyl/atracurium, and maintained with isoflurane/N2O/fentanyl at normocapnia. After removal of the bone flap and exposure of intact dura, ICP was measured subdurally and dihydroergotamine/placebo was administered. Intracranial pressure and MABP were measured continuously. Cerebral blood flow (after intravenous administration of 133Xe) and arteriojugular venous difference of oxygen (AVDO2) were measured before, and 30 minutes after, dihydroergotamine/placebo administration. Cerebral metabolic rate of oxygen (CMRO2) was calculated. After administration of dihydroergotamine, a significant increase in MABP from 74 to 87 mm Hg (median) and CPP from 65 to 72 mm Hg (median) were found. Simultaneously to the increase in MABP, a significant increase in ICP from 9.5 to 11.5 mm Hg (median) was disclosed, whereas no significant differences in CBF, AVDO2, or CMRO2 were found. Intracranial pressure was significantly higher after dihydroergotamine than after placebo. In conclusion, no ICP decreasing effect of a bolus dose of dihydroergotamine was found when administered to patients with brain tumors during isoflurane/N2O anesthesia. Corresponding increases in MABP and ICP suggest that abolished cerebral autoregulation might explain why dihydroergotamine was associated with an ICP increase.     

The Brain Trauma Foundation. The American Association of Neurological Surgeons. The Joint Section on Neurotrauma and Critical Care. Indications for intracranial pressure monitoring

ICP monitoring per se has never been subjected to a prospective randomized clinical trial (PRCT) to establish its efficacy (or lack thereof) in improving outcome from severe head injury. Hence, there are insufficient data to support its use as a standard. However, there is a large body of published clinical experience that indicates that ICP monitoring (1) helps in the earlier detection of intracranial mass lesions, (2) can limit the indiscriminate use of therapies to control ICP which themselves can be potentially harmful, (3) can reduce ICP by CSF drainage and thus improve cerebral perfusion, (4) helps in determining prognosis, and (5) may improve outcome. ICP monitoring is therefore used by most head injury experts in the United States and is accepted as a relatively low-risk high-yield, modest cost intervention. Comatose head injury patients (GCS 3-8) with abnormal CT scans should undergo ICP monitoring. Comatose patients with normal CT scans have a much lower incidence of intracranial hypertension unless they have two or more of the following features at admission: age over 40, unilateral or bilateral motor posturing, or a systolic blood pressure of less than 90 mm Hg. ICP monitoring in patients with a normal CT scan with two or more of these risk factors is suggested as a guideline. Routine ICP monitoring is not indicated in patients with mild or moderate head injury. However, it may be undertaken in certain conscious patients with traumatic mass lesions at the discretion of the treating physician.     

Is computed tomographic scanning necessary in patients with tentorial herniation? Results of immediate surgical exploration without computed tomography in 100 patients

Computed tomographic (CT) scans are performed on virtually all patients with severe head injury at the time of admission. Because of the time involved in obtaining these studies, the evacuation of significant intracranial mass lesions is delayed. To avoid such delays, the authors performed burr-hole exploration for the diagnosis of intracranial hematomas before CT scans were obtained in 100 consecutive head-injured patients with clinical signs of tentorial herniation or upper brain stem dysfunction upon admission to the emergency room. Patients in whom a hematoma was discovered had a craniotomy for evacuation of the clot; those in whom the exploration was negative had a CT brain scan immediately after operation. Burr-hole exploration revealed extracerebral mass lesions in 56 patients. In 38 patients, the exploration was negative, and postoperative CT scanning showed no significant hematoma. Of 6 patients in whom the CT scan demonstrated extraaxial hematomas requiring surgical evacuation, 4 had subdural hematomas that were missed because the exploration was incomplete; 1 patient had an epidural hematoma and 1 had a subdural hematoma contralateral to a craniotomy on the side of a positive initial burr-hole exploration. Our results indicate that the relatively small subgroup of head-injured patients with early tentorial herniation or upper brain stem compression have a high incidence of immediate extraaxial hematomas and a low incidence of intracerebral hematomas. This is particularly true of patients over 30 years of age and those who suffer low speed trauma, such as falls and vehicle-pedestrian accidents.