Stilbazulenyl nitrone, a novel azulenyl nitrone antioxidant, improved neurological deficit and reduced contusion size after traumatic brain injury in rats

2002 ◽  
Vol 96 (6) ◽  
pp. 1077-1083 ◽  
Author(s):  
Ludmila Belayev ◽  
David A. Becker ◽  
Ofelia F. Alonso ◽  
Yitao Liu ◽  
Raul Busto ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Brain Temperature ◽  
Antioxidant Properties ◽  
Neurological Status ◽  
Sprague Dawley ◽  
Content Type ◽  
Fluid Percussion ◽  
Cortical Contusion ◽  
Fine Print

Object. Stilbazulenyl nitrone (STAZN) is a second-generation azulenyl nitrone that has markedly enhanced antioxidant properties compared with those of conventional alpha-phenyl nitrones. In this study, the authors assessed the potential efficacy of STAZN in a rodent model of fluid-percussion brain injury, which results in a consistent cortical contusion. Methods. After anesthesia had been induced in normothermic Sprague—Dawley rats (brain temperature 36–36.5°C) by halothane—nitrous oxide, the animals were subjected to a right parietooccipital parasagittal fluid-percussion injury (1.5–2 atm). The agent (STAZN, 30 mg/kg; eight animals) or vehicle (dimethyl sulfoxide; eight animals) was administered intraperitoneally at 5 minutes and 4 hours after trauma. The neurological status of each rat was evaluated on Days 1, 2, and 7 postinjury (normal score 0, maximum injury 12). Seven days after trauma, the rat brains were perfusion fixed, coronal sections at various levels were digitized, and areas of contusion were measured. Treatment with STAZN significantly improved neurological scores on Days 2 and 7 postinjury compared with vehicle-treated rats. Administration of STAZN also significantly reduced the total contusion area by 63% (1.8 ± 0.5 mm2 in STAZN-treated animals compared with 4.8 ± 2.1 mm2 in vehicle-treated animals; p = 0.04) and the deep cortical contusion area by 60% (1.2 ± 0.2 mm2 in STAZN-treated animals compared with 2.9 ± 1.2 mm2 in vehicle-treated animals; p = 0.03). By contrast, hippocampal cell loss in the CA3 sector was unaffected by STAZN treatment. Conclusions. Therapy with STAZN, a novel potent antioxidant, administered following traumatic brain injury, markedly improves neurological and histological outcomes. Azulenyl nitrones appear to represent a promising class of neuroprotective agents for combating this devastating condition.

Loss of forebrain cholinergic neurons following fluid-percussion injury: implications for cognitive impairment in closed head injury

1995 ◽  
Vol 83 (3) ◽  
pp. 496-502 ◽  
Author(s):  
Richard H. Schmidt ◽  
M. Sean Grady
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Head Injury ◽  
Cholinergic Neurons ◽  
Nucleus Basalis ◽  
Neuron Loss ◽  
Content Type ◽  
Fluid Percussion ◽  
Concussive Injury ◽  
Fine Print

✓ Disturbances in memory, concentration, and problem solving are common after even mild to moderate traumatic brain injury. Because these functions are mediated in part by forebrain cholinergic and catecholaminergic innervation, in this study the authors sought to determine if experimental concussive injury produces detectable morphological damage to these systems. Fluid-percussion head injury, sufficient to cause a 13- to 14-minute loss of righting reflex, was produced in rats that had been anesthetized with halothane. Injury was delivered either at midline or 2 mm off midline and compared with appropriate sham-injured controls. After 11 to 15 days, the rat brains were stained in serial sections for choline acetyltransferase, tyrosine hydroxylase, dopamine β-hydroxylase, acetylcholinesterase, and nicotinamide adenine dinucleotide phosphate diaphorase. Cell counts were determined for the entire population of ventrobasal forebrain cholinergic cells. Midline injury produced a bilateral loss of cholinergic neurons averaging 36% in area Ch1 (medial septal nucleus), 45% in Ch2 (nucleus of the diagonal band of Broca), and 41% in Ch4 (nucleus basalis of Meynart), (p ≤ 0.05). Lateralized injury resulted in cholinergic neuron loss of similar magnitude ipsilaterally (p ≤ 0.05), but a smaller contralateral loss of between 11% and 28%. No loss of neurons was detected in the pontomesencephalic cholinergic groups Ch5 and Ch6. There was no visible effect of head injury on forebrain dopamine or noradrenergic innervation. A significant and apparently selective loss of ventrobasal forebrain cholinergic neurons following brief concussive injury in rats is demonstrated in this study. This type of injury is known to produce significant disturbance in cognitive tasks linked to neocortical and hippocampal cholinergic function. It remains to be determined how this neuron loss occurs, whether it can be prevented with neuroprotective agents, how it affects innervation in target tissues, and whether it occurs in human victims of traumatic brain injury.

The effect of brain temperature on hemoglobin extravasation after traumatic brain injury

2002 ◽  
Vol 97 (4) ◽  
pp. 945-953 ◽  
Author(s):  
Kosaku Kinoshita ◽  
Katina Chatzipanteli ◽  
Ofelia F. Alonso ◽  
Mackenzie Howard ◽  
W. Dalton Dietrich
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Injury Severity ◽  
Brain Temperature ◽  
Experimental Studies ◽  
Hemoglobin Concentration ◽  
Contralateral Hemisphere ◽  
Ipsilateral Hemisphere ◽  
Content Type ◽  
Fine Print

Object. Although the benefits of posttraumatic hypothermia have been reported in experimental studies, the potential for therapeutic hypothermia to increase intracerebral hemorrhage remains a clinical concern. The purpose of this study was to quantify the amount of extravasated hemoglobin after traumatic brain injury (TBI) and to assess the changes in intracerebral hemoglobin concentrations under posttraumatic hypothermic and hyperthermic conditions. Methods. Intubated and anesthetized rats were subjected to fluid-percussion injury (FPI). In the first experiment, rats were divided into moderate (1.8–2.2 atm) and severe (2.4–2.7 atm) TBI groups. In the second experiment, the effects of 3 hours of posttraumatic hypothermia (33 or 30°C), hyperthermia (39°C), or normothermia (37°C) on hemoglobin levels following moderate trauma were assessed. The rats were perfused with saline at 24 hours postinjury, and then the traumatized and contralateral hemispheres, including the cerebellum, were dissected from whole brain. The hemoglobin level in each brain was quantified using a spectrophotometric hemoglobin assay. The results of these assays indicate that moderate and severe FPI induce increased levels of hemoglobin in the ipsilateral hemisphere (p < 0.0001). After severe TBI, the hemoglobin concentration was also significantly increased in the contralateral hemisphere (p < 0.05) and cerebellum (p < 0.005). Posttraumatic hypothermia (30°C) attenuated hemoglobin levels (p < 0.005) in the ipsilateral hemisphere, whereas hyperthermia had a marked adverse effect on the hemoglobin concentration in the contralateral hemisphere (p < 0.05) and cerebellum (p < 0.005). Conclusions. Injury severity is an important determinant of the degree of hemoglobin extravasation after TBI. Posttraumatic hypothermia reduced hemoglobin extravasation, whereas hyperthermia increased hemoglobin levels compared with normothermia. These findings are consistent with previous data reporting that posttraumatic temperature manipulations alter the cerebrovascular and inflammatory consequences of TBI.

Exacerbation of cortical and hippocampal CA1 damage due to posttraumatic hypoxia following moderate fluid-percussion brain injury in rats

1999 ◽  
Vol 91 (4) ◽  
pp. 653-659 ◽  
Author(s):  
Helen M. Bramlett ◽  
Edward J. Green ◽  
W. Dalton Dietrich
Keyword(s):  
Brain Injury ◽  
Head Injuries ◽  
Human Head ◽  
Qualitative Assessment ◽  
Subcortical Structures ◽  
Content Type ◽  
Fluid Percussion ◽  
Fluid Percussion Injury ◽  
Cortical Contusion ◽  
Fine Print

Object. Patients with head injuries often experience respiratory distress that results in a secondary hypoxic insult. The present experiment was designed to assess the histopathological consequences of a secondary hypoxic insult by using an established rodent model of traumatic brain injury (TBI).Methods. Intubated anesthetized rats were subjected to moderate (1.94–2.18 atm) parasagittal fluid-percussion injury (FPI) to the brain. Following the TBI, the animals were maintained for 30 minutes by using either hypoxic (TBI-HY group, nine animals) or normoxic (TBI-NO, 10 animals) gas levels. Sham-operated animals also underwent all manipulations except for the FPI (sham-HY group, seven animals; and sham-NO group, seven animals). Three days after TBI the rats were killed, and quantitative histopathological evaluation was undertaken. Cortical contusion volumes were dramatically increased in the TBI-HY group compared with the TBI-NO group (p < 0.03). Qualitative assessment of cortical and subcortical structures demonstrated significant damage within the hippocampal areas, CA1 and CA2, of TBI-HY animals compared with the TBI-NO animals (both p < 0.03). There was also a significant increase in the frequency of damaged neuronal profiles within the middle and medial sectors of the CA1 hippocampus (p < 0.03) due to the hypoxic insult.Conclusions. The results of this study demonstrate that a secondary hypoxic insult following parasagittal FPI exacerbates contusion and neuronal pathological conditions. These findings emphasize the need to control for secondary hypoxic insults after experimental and human head injury.

Role of nitric oxide in traumatic brain injury in the rat

1998 ◽  
Vol 89 (5) ◽  
pp. 807-818 ◽  
Author(s):  
Kojiro Wada ◽  
Katina Chatzipanteli ◽  
Raul Busto ◽  
W. Dalton Dietrich
Keyword(s):  
Nitric Oxide ◽  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Specific Inhibitor ◽  
Dependent Manner ◽  
Histopathological Response ◽  
Content Type ◽  
Fluid Percussion ◽  
Neuronal Nos ◽  
Fine Print

Object. Although nitric oxide (NO) has been shown to play an important role in the pathophysiological process of cerebral ischemia, its contribution to the pathogenesis of traumatic brain injury (TBI) remains to be clarified. The authors investigated alterations in constitutive nitric oxide synthase (NOS) activity after TBI and the histopathological response to pharmacological manipulations of NO. Methods. Male Sprague—Dawley rats underwent moderate (1.7–2.2 atm) parasagittal fluid-percussion brain injury. Constitutive NOS activity significantly increased within the ipsilateral parietal cerebral cortex, which is the site of histopathological vulnerability, 5 minutes after TBI occurred (234.5 ± 60.2% of contralateral value [mean ± standard error of the mean {SEM}], p < 0.05), returned to control values by 30 minutes (114.1 ± 17.4%), and was reduced at 1 day after TBI (50.5 ± 13.1%, p < 0.01). The reduction in constitutive NOS activity remained for up to 7 days after TBI (31.8 ± 6.0% at 3 days, p < 0.05; 20.1 ± 12.7% at 7 days, p < 0.01). Pretreatment with 3-bromo-7-nitroindazole (7-NI ) (25 mg/kg), a relatively specific inhibitor of neuronal NOS, significantly decreased contusion volume (1.27 ± 0.17 mm3 [mean ± SEM], p < 0.05) compared with that of control (2.52 ± 0.35 mm3). However, posttreatment with 7-NI or pre- or posttreatment with nitro-l-arginine-methyl ester (l-NAME) (15 mg/kg), a nonspecific inhibitor of NOS, did not affect the contusion volume compared with that of control animals (1.87 ± 0.46 mm3, 2.13 ± 0.43 mm3, and 2.18 ± 0.53 mm3, respectively). Posttreatment with l-arginine (1.1 ± 0.3 mm3, p < 0.05), but not 3-morpholino-sydnonimine (SIN-1) (2.48 ± 0.37 mm3), significantly reduced the contusion volume compared with that of control animals. Conclusions. These data indicate that constitutive NOS activity is affected after moderate parasagittal fluid percussion brain injury in a time-dependent manner. Inhibition of activated neuronal NOS and/or enhanced endothelial NOS activation may represent a potential therapeutic strategy for the treatment of TBI.

Regulation of aquaporin-4 in a traumatic brain injury model in rats

2003 ◽  
Vol 98 (3) ◽  
pp. 565-569 ◽  
Author(s):  
Ming-Chieh Sun ◽  
Christopher R. Honey ◽  
Caglar Berk ◽  
Norman L. M. Wong ◽  
Joseph K. C. Tsui
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Parietal Cortex ◽  
Occipital Cortex ◽  
Aquaporin 4 ◽  
Frontal Pole ◽  
Injury Site ◽  
Content Type ◽  
Cortical Contusion ◽  
Fine Print

Object. Aquaporin-4 (AQP4) plays a significant role in the regulation of brain water homeostasis. In this study the authors investigated the regulation of AQP4 following a focal cortical contusion injury in rats. Methods. Thirty-three adult male Wistar rats received a focal cortical contusion of the parietal cortex. An additional nine rats underwent a craniectomy, but no trauma was inflicted (sham injury). Animals were killed 1, 4, and 24 hours later. The rat brains were examined for water content by comparing the wet and dry weights of each hemisphere. Aquaporin-4 messenger (m)RNA was measured by reverse transcription—polymerase chain reaction. A ratio of AQP4 mRNA expression in the lesioned hemisphere compared with that in the contralateral control hemisphere was calculated for each animal at the injury site (parietal cortex) and at sites adjacent to (occipital cortex) and distant from the injury (frontal pole cortex). Brain edema was significantly increased at the injury site. The expression of AQP4 mRNA was significantly increased at the injury site, significantly decreased adjacent to the injury site, and not significantly different at a site distant from the injury. The magnitude of AQP4 mRNA upregulation at the injured parietal cortex correlated with the degree of downregulation in the adjacent occipital cortex. Conclusions. Data from this study demonstrate that an upregulation of AQP4 occurs at the site of traumatic brain injury and that a downregulation of this molecule occurs adjacent to the site of injury. Understanding the physiology of AQP4 and its regulation following brain injury may allow for the development of novel treatments for cerebral edema that accompanies head injury.

Effects of delayed, prolonged hypothermia on the pial vascular response after traumatic brain injury in rats

2003 ◽  
Vol 99 (5) ◽  
pp. 899-906 ◽  
Author(s):  
Yuji Ueda ◽  
Enoch P. Wei ◽  
Hermes A. Kontos ◽  
Eiichi Suehiro ◽  
John T. Povlishock
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Sprague Dawley ◽  
Content Type ◽  
Potential Efficacy ◽  
Vascular Responsiveness ◽  
Group 2 ◽  
C 30 ◽  
Normothermic Group ◽  
Fine Print

Object. In the experimental setting, hypothermia has been demonstrated to attenuate the damaging consequences of stroke and traumatic brain injury (TBI). Laboratory studies of TBI have focused primarily on the use of early hypothermic intervention, with little consideration of the potential efficacy of more delayed but prolonged hypothermia, which would constitute a more clinically relevant approach. In this investigation, the authors evaluated whether delayed, prolonged hypothermia after TBI protected the cerebral microcirculation. Methods. Male Sprague—Dawley rats were equipped with cranial windows for direct visualization of the pial arterial circulation and then subjected to impact-acceleration brain injury. The rats were randomly divided into four experimental groups: Group 1 consisted of normothermic animals; in Group 2 the rats received a 1-hour period of hypothermia (32°C) 30 minutes posttrauma, followed by slow rewarming (32–37°C/90 minutes); and in Groups 3 and 4 the rats received a more delayed induction (at 1 hour postinjury) of either 1 hour (Group 3) or 2 hours (Group 4) of hypothermia, followed by the slow rewarming. The pial arteriolar responses to acetylcholine (ACh) or hypercapnia were measured until up to 6 hours postinjury. With this approach the authors found that the normothermic group demonstrated severely impaired vasoreactivity in terms of ACh-dependent dilation and CO2 reactivity in comparison to baseline values (p < 0.001). In contrast, hypothermia of short duration that was initiated early (30 minutes postinjury) conferred significant cerebrovascular protection (p < 0.001), yet this protection was reduced when the onset of this 1-hour hypothermic period was postponed to 1 hour postinjury. Nevertheless, reduced protection could be significantly improved (p < 0.001) with prolongation of the hypothermic period to 2 hours. Conclusions. The results of this study show that early as well as delayed but prolonged hypothermia attenuate the impaired vascular responsiveness seen after TBI, indicating the potential clinical usefulness of this treatment.

Cytidinediphosphocholine treatment to decrease traumatic brain injury—induced hippocampal neuronal death, cortical contusion volume, and neurological dysfunction in rats

2003 ◽  
Vol 98 (4) ◽  
pp. 867-873 ◽  
Author(s):  
Robert J. Dempsey ◽  
Vemuganti L. Raghavendra Rao
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Neuronal Death ◽  
Hippocampal Neurons ◽  
Neurological Dysfunction ◽  
Adult Rats ◽  
Edema Formation ◽  
Content Type ◽  
Cortical Contusion ◽  
Fine Print

Object. In previous studies at their laboratory the authors showed that cytidinediphosphocholine (CDP-choline), an intermediate of phosphatidylcholine synthesis, decreases edema formation and blood—brain barrier disruption following traumatic brain injury (TBI). In the present study the authors investigate whether CDP-choline protects hippocampal neurons after controlled cortical impact (CCI)—induced TBI in adult rats. Methods. After adult male Sprague—Dawley rats had been anesthetized with halothane, a moderate-grade TBI was induced with the aid of a CCI device set at a velocity of 3 m/second, creating a 2-mm deformation. Sham-operated rats, which underwent craniectomy without impact served as controls. The CDP-choline (100, 200, and 400 mg/kg body weight) or saline was injected into the animals twice (once immediately postinjury and once 6 hours postinjury). Seven days after the injury, the rats were neurologically evaluated and killed, and the number of hippocampal neurons was estimated by examining thionine-stained brain sections. By 7 days postinjury, there was a significant amount of neuronal death in the ipsilateral hippocampus in the CA2 (by 53 ± 7%, p < 0.05) and CA3 (by 59 ± 9%, p < 0.05) regions and a contusion (volume 34 ± 8 mm3) in the ipsilateral cortex compared with sham-operated control animals. Rats subjected to TBI also displayed severe neurological deficit at 7 days postinjury. Treating rats with CDP-choline (200 and 400 mg/kg, intraperitoneally) significantly prevented TBI-induced neuronal loss in the hippocampus, decreased cortical contusion volume, and improved neurological recovery. Conclusions. Treatment with CDP-choline decreased brain damage following TBI.

Flushing in relation to a possible rise in intracranial pressure: documentation of an unusual clinical sign

2000 ◽  
Vol 92 (6) ◽  
pp. 1040-1044 ◽  
Author(s):  
Gregory W. Hornig
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Intracranial Pressure ◽  
Intraventricular Hemorrhage ◽  
Pneumococcal Meningitis ◽  
Clinical Importance ◽  
Neurological Deterioration ◽  
Content Type ◽  
Transient Nature ◽  
Fine Print

✓ This report documents clinical features in five children who developed transient reddening of the skin (epidermal flushing) in association with acute elevations in intracranial pressure (ICP). Four boys and one girl (ages 9–15 years) deteriorated acutely secondary to intracranial hypertension ranging from 30 to 80 mm Hg in the four documented cases. Two patients suffered from ventriculoperitoneal shunt malfunctions, one had diffuse cerebral edema secondary to traumatic brain injury, one was found to have pneumococcal meningitis and hydrocephalus, and one suffered an intraventricular hemorrhage and hydrocephalus intraoperatively. All patients were noted to have developed epidermal flushing involving either the upper chest, face, or arms during their period of neurological deterioration. The response was transient, typically lasting 5 to 15 minutes, and dissipated quickly. The flushing reaction is postulated to be a centrally mediated response to sudden elevations in ICP. Several potential mechanisms are discussed. Flushing has clinical importance because it may indicate significant elevations in ICP when it is associated with neurological deterioration. Because of its transient nature, the importance of epidermal flushing is often unrecognized; its presence confirms the need for urgent treatment.

Intracranial bone marrow transplantation after traumatic brain injury improving functional outcome in adult rats

2001 ◽  
Vol 94 (4) ◽  
pp. 589-595 ◽  
Author(s):  
Asim Mahmood ◽  
Dunyue Lu ◽  
Yi Li ◽  
Jae Li Chen ◽  
Michael Chopp
Keyword(s):  
Traumatic Brain Injury ◽  
Bone Marrow ◽  
Brain Injury ◽  
Motor Function ◽  
Glial Fibrillary Acid Protein ◽  
Protein Markers ◽  
Adult Rats ◽  
Content Type ◽  
The Impact ◽  
Fine Print

Object. The authors tested the hypothesis that intracranial bone marrow (BM) transplantation after traumatic brain injury (TBI) in rats provides therapeutic benefit. Methods. Sixty-six adult Wistar rats, weighing 275 to 350 g each, were used for the experiment. Bone marrow prelabeled with bromodeoxyuridine (BrdU) was harvested from tibias and femurs of healthy adult rats. Other animals were subjected to controlled cortical impact, and BM was injected adjacent to the contusion 24 hours after the impact. The animals were killed at 4, 7, 14, or 28 days after transplantation. Motor function was evaluated both before and after the injury by using the rotarod test. After the animals had been killed, brain sections were examined using hemotoxylin and eosin and immunohistochemical staining methods. Histological examination revealed that, after transplantation, BM cells survived, proliferated, and migrated toward the injury site. Some of the BrdU-labeled BM cells were reactive, with astrocytic (glial fibrillary acid protein) and neuronal (NeuN and microtubule-associated protein) markers. Transplanted BM expressed proteins phenotypical of intrinsic brain cells, that is, neurons and astrocytes. A statistically significant improvement in motor function in rats that underwent BM transplantation, compared with control rats, was detected at 14 and 28 days posttransplantation. Conclusions. On the basis of their findings, the authors assert that BM transplantation improves neurological outcome and that BM cells survive and express nerve cell proteins after TBI.

Cerebral tissue PO2 and SjvO2 changes during moderate hyperventilation in patients with severe traumatic brain injury

2002 ◽  
Vol 96 (1) ◽  
pp. 97-102 ◽  
Author(s):  
Roberto Imberti ◽  
Guido Bellinzona ◽  
Martin Langer
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Brain Tissue ◽  
Severe Traumatic Brain Injury ◽  
Cerebral Perfusion ◽  
Content Type ◽  
Secondary Damage ◽  
Tissue Po2 ◽  
Two Parameters ◽  
Fine Print

Object. The aim of this study was to investigate the effects of moderate hyperventilation on intracranial pressure (ICP), jugular venous oxygen saturation ([SjvO2], an index of global cerebral perfusion), and brain tissue PO2 (an index of local cerebral perfusion). Methods. Ninety-four tests consisting of 20-minute periods of moderate hyperventilation (27–32 mm Hg) were performed on different days in 36 patients with severe traumatic brain injury (Glasgow Coma Scale score ≤ 8). Moderate hyperventilation resulted in a significant reduction in average ICP, but in seven tests performed in five patients it was ineffective. The response of SjvO2 and brain tissue PO2 to CO2 changes was widely variable and unpredictable. After 20 minutes of moderate hyperventilation in most tests (79.8%), both SjvO2 and brain tissue PO2 values remained above the lower limits of normality (50% and 10 mm Hg, respectively). In contrast, in 15 tests performed in six patients (16.6% of the studied population) brain tissue PO2 decreased below 10 mm Hg although the corresponding SjvO2 values were greater than 50%. The reduction of brain tissue PO2 below 10 mm Hg was favored by the low prehyperventilation values (10 tests), higher CO2 reactivity, and, possibly, by lower prehyperventilation values of cerebral perfusion pressure. In five of those 15 tests, the prehyperventilation values of SjvO2 were greater than 70%, a condition of relative hyperemia. The SjvO2 decreased below 50% in four tests; the corresponding brain tissue PO2 values were less than 10 mm Hg in three of those tests, whereas in the fourth, the jugular venous O2 desaturation was not detected by brain tissue PO2. The analysis of the simultaneous relative changes (prehyperventilation — posthyperventilation) of SjvO2 and brain tissue PO2 showed that in most tests (75.5%) there was a reduction of both SjvO2 and brain tissue PO2. In two tests moderate hyperventilation resulted in an increase of both SjvO2 and brain tissue PO2. In the remaining 17 tests a redistribution of the cerebral blood flow was observed, leading to changes in SjvO2 and brain tissue PO2 in opposite directions. Conclusions. Hyperventilation, even if moderate, can frequently result in harmful local reductions of cerebral perfusion that cannot be detected by assessing SjvO2. Therefore, hyperventilation should be used with caution and should not be considered safe. This study confirms that SjvO2 and brain tissue PO2 are two parameters that provide complementary information on brain oxygenation that is useful to reduce the risk of secondary damage. Changes in SjvO2 and brain tissue PO2 in opposite directions indicate that data obtained from brain tissue PO2 monitoring cannot be extrapolated to evaluate the global cerebral perfusion.

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