ISSN:0898-4921    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Various surgical procedures may cause temporary interruption of spinal cord blood supply and may result in irreversible ischemic injury and neurological deficits. The cascade of events that leads to neuronal death following ischemia may be amenable to pharmacological manipulations that aim to increase the tolerable duration of ischemia. Many agents have been evaluated in experimental spinal cord ischemia (SCI). In order to investigate whether an agent is available that justifies clinical evaluation, the literature on pharmacological neuroprotection in experimental SCI was systematically reviewed to assess the neuroprotective efficacy of the various agents. In addition, the strength of the evidence for neuroprotection was investigated by analyzing the methodology. The authors used a systematic review to conduct this evaluation. The included studies were analyzed for neuroprotection and methodology. In order to be able to compare the various agents for neuroprotective efficacy, relative risks and confidence intervals were calculated from the data in the results sections. A total of 103 studies were included. Seventy-nine different agents were tested. Only 14 of the agents tested did not afford protection at all. A large variation was observed in the experimental models to produce SCI. This variation limited comparison of the individual agents. In 48 studies involving 31 single agents, the relative risks and confidence intervals could be calculated. An analysis of the methodology revealed poor temperature management and lack of statistical power in the majority of the 103 studies. The results suggest that numerous agents may protect the spinal cord from transient ischemia. However, poor temperature management and lack of statistical power severely weakened the evidence. Consequently, clinical evaluation of pharmacological neuroprotection in surgical procedures that carry a risk of ischemic spinal cord damage is not justified on the basis of this study.

ISSN:0898-4921    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

The authors examined the relationship between fibrin degradation products (FDP) and outcome in children with isolated head injury by reviewing the records of 69 children who met the following criteria: (1) less than 16 years of age; (2) diagnosis of isolated head injury and (3) FDP levels. Outcome was evaluated using the following Glasgow Outcome Scale (GOS): 1 = death; 2 = vegetative state; 3 = functionally impaired; 4 = minimal dysfunction; 5 = premorbid level of functioning. Poor outcome was defined as GOS 1–3. Twenty-nine of 33 patients with FDP > 1000 (g/mL had GOS scores < 4 compared to 4/36 patients (11%) with FDP < 1000 &mgr;g/mL (Fisher's Exact Probability TestP< .0001). When stratified by GCS, no other prognosticator of outcome was needed when GCS was < 7 and > 12. In patients with GCS 7–12, however, 4/6 with FDP >1000 &mgr;g/mL had a poor outcome and all 12 patients with FDP < 1000 &mgr;g/mL had a good outcome (P= .004). The authors conclude that FDP > 1000 &mgr;g/mL predicts poor outcome in children with isolated head injury. Fibrin degradation products are a strong independent prognosticator of outcome in children when GCS is between 7 and 12.

ISSN:0898-4921    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Cocktails of neuroprotectants acting at different parts of the ischemic injury cascade may have advantages over single agents. This study investigated, singly and in combination, the neuroprotective efficacy of an energy substrate (3.5 mM fructose 1,6-bisphosphate, FBP), an antagonist of NMDA receptors (1 and 10 &mgr;M MK-801), a free-radical scavenger (100 &mgr;M ascorbate), an adenosine A1 receptor agonist (10 &mgr;M 2-chloroadenosine), and an inhibitor of neurotransmission (2% isoflurane). These agents were evaluated for their ability to prevent loss and morphologic damage of CA1 neurons in rat hippocampal slices when these agents were administered during 30 minutesin vitroischemia (combined oxygen/glucose deprivation at 37°C) followed by 5 hours of recovery. Ten &mgr;M MK-801, alone or in combination with the other compounds, prevented loss of CA1 neurons and preserved their histologic appearance. Isoflurane, which prevents glutamate receptor-dependent cell death in this model, was also protective. Protection against neuron loss was also found when a subtherapeutic concentration of MK-801 (1 &mgr;M) was combined with 2-chloroadenosine (which indirectly causes NMDA receptor suppression), but not FBP or ascorbate. The authors conclude that in this model, the strategy of antagonizing NMDA receptors appears more protective than fructose-1,6-bisphosphate, 2-chloroadenosine or ascorbate.

ISSN:0898-4921    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

The effects of anesthetics on the generation of cortical spreading depression (CSD) were investigated. Volatile anesthetics halothane, isoflurane, sevoflurane (0.5, 1.0, and 2.0 MAC), and the intravenous anesthetic pentobarbital were studied. Cortical spreading depression was induced by 3M-KCI applied to a surface of brain cortex for 30 minutes. Direct current (DC) potential was recorded, and the number, amplitude, and duration of CSDs were observed. With increasing concentrations of each volatile anesthetic, there was a dose-related reduction in CSD frequency but not in CSD amplitude. At 2.0 MAC of sevoflurane the suppression of CSD was less than with the other volatile anesthetics. In addition, the influence of anesthetics on expression of c-fos mRNA was investigated. Additional animals anesthetized by isoflurane or sevoflurane were studied. Five CSDs were elicited by electric stimulation (0.5 mV, l second) in each animal.In situhybridization with 35S-labeled oligonucleotides was used to evaluate the level of c-fos mRNA. The expression of c-fos was observed in the hemisphere in which CSD was elicited, but there was no difference in expression of c-fos among the groups. We conclude that volatile anesthetics can induce suppression of CSD elicitation in a dose dependent manner, but that at high concentrations sevoflurane is significantly less effective than other volatile agents. Pentobarbital has the least effect on KCl-induced CSD. These data suggest that the choice of anesthetics can impact the results of studies examining membrane depolarization and the ionic changes initiated by CSD.

ISSN:0898-4921    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

This study sought to determine the maximum tolerable limit of anemia for the brain during halothane anesthesia. Using a multiparameter sensor, we continuously monitored brain tissue oxygen tension (PO2), carbon dioxide tension (PCO2), and pH during profound hemodilution and subsequent transfusion. Twelve New Zealand White rabbits were anesthetized, intubated, and mechanically ventilated at a fraction of inspired oxygen (FiO2) of 21% to produce an arterial carbon dioxide tension (PaCO2) of 35 to 40 mm Hg. The femoral artery was cannulated to continuously monitor arterial blood pressure and to intermittently measure arterial blood gases. The electroencephalogram (EEG) was recorded throughout the course of the study. A fiberoptic sensor was inserted into the brain for the continuous measurement of brain PO2, PCO2, pH, and temperature. Cerebral blood flow (CBF) was measured by the hydrogen clearance method. Severe anemia was induced by repeatedly withdrawing 50-mL aliquots of blood and infusing an equal volume of 6% hetastarch. This procedure was performed four times for each rabbit. After the forth blood draw and fluid infusion, a total of 60 mL of packed red blood cells were transfused. Upon completion of the hemodilution, the hemoglobin concentration was 2.4 ± 0.3 g/dL (mean ± SEM). Brain tissue PO2decreased from 27 ± 3 mm Hg to a minimum of 12 ± 2 mm Hg. Brain tissue pH also decreased from 7.22 ± 0.03 to 7.12 ± 0.05 and returned to the baseline value with transfusion. Brain PCO2did not change significantly during the experiment. Cerebral blood flow increased from 37 ± 3 to 66 ± 15 mL × 100g−1× min−1during hemodilution and returned to baseline after infusion of red blood cells. There was some loss of EEG amplitude and the calculated cerebral metabolic rate (CMRO2) decreased from 4.3 ± 0.6 to 1.9 ± 0.3 mL × 100g−1× min−1at the most profound level of anemia. This is the first report of which the authors are aware of continuous monitoring of brain tissue pH, PCO2, and PO2during profound hemodilution and transfusion. Hemodilution results in a decrease in brain tissue PO2. Increases in CBF and oxygen extraction can only partially compensate for the decreased oxygen carrying capacity of the blood. Decreases in brain tissue PO2, pH, CMRO2, and a loss of EEG amplitude suggest that the maximum tolerable limit of hemodilution was achieved in this study.

ISSN:0898-4921    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

SummaryThe newest therapy for cerebral aneurysm is the Guglielmi detachable coil (GDC). The authors describe the anesthetic management of two patients with intraoperative subarachnoid hemorrhage during Guglielmi coil placement. Various treatments for intraoperative hemorrhage are discussed, as are other common complications that can occur during placement of intravascular, intracranial coils. The placement of a ventriculostomy was a major contributing factor in the good outcome of both patients. Consideration should be given to placement of a ventriculostomy before the GDC procedure. Although the GDC procedure offers much promise, it is not a benign procedure and has its own set of complications that will no doubt challenge the neuroanesthesiologist.

ISSN:0898-4921    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Changes in cerebral hemodynamics and oxygenation patterns in cerebral vasospasm might be underestimated if transcranial doppler sonography and angiography findings are considered singularly. This report describes preliminary findings in further development of a noninvasive method that estimates regional cerebral oxygenation and perfusion. A 50-year-old patient suffering from cerebral vasospasm after subarachnoid hemorrhage before and after superselective papaverine infusion was examined. Measurements were taken by using a technique combining indocyaningreen dye dilution and near infrared spectroscopy. Our first results suggest that the technique could be suitable for estimation of cerebral hemodynamics. This noninvasive technique can be performed at the bedside and in special environments, such as neurocritical care units. It seems to be safe, easy to perform, and less time-consuming than conventional techniques. Combination of indocyaningreen dye dilution and near infrared spectroscopy might become a powerful tool in the detection and treatment of cerebral vasospasm causing delayed cerebral ischemic deficit. Further larger-scale investigations are necessary to evaluate the diagnostic accuracy of this technique. Our preliminary observations however, based on measurements before and after superselective papaverine infusion in vasospastic vessels, helped to clarify the influence of extracerebral contamination on the cerebral near infrared spectroscopy signal in the adult head.

ISSN:0898-4921    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:0898-4921    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

This study will determine if early administration of antithrombin concentrate to patients with traumatic brain injury (TBI) can inhibit or significantly shorten the time of coagulopathy. The progress of brain injury monitored by computed tomographic scan (CT) was also assessed, as was the time needed for intensive care and outcome related to Glasgow outcome scale (GOS). Twenty-eight patients with isolated brain trauma verified with CT were included in either of two parallel groups. The Glasgow coma score (GCS) was mean 7.5, and median 7.0; signifying a moderate to severe traumatic brain injury but with a mortality of only 3.5 %. The patients randomized to antithrombin treatment received a total of 100 U/kg BW during 24 hours. To measure hypercoagulability, soluble fibrin (SF), D-dimer (D-d), and thrombin-antithrombin complex (TAT) were assessed together with antithrombin (AT) and routine coagulation tests. Before treatment, SF, D-d, and TAT were markedly increased in both groups. Soluble fibrin and D-dimer (measured after treatment began) appeared to decrease faster in the AT group, and there was a statistically significant difference between the groups at 36 hours for SF and at 36 hours, 48 hours, and at Day 3 for D-d. Thrombin-antithrombin complex levels were very high in both groups but, surprisingly, showed no significant difference between the groups. The authors conclude that antithrombin concentrate administered to patients with severe TBI resulted in a marginal reduction of hypercoagulation. We could not detect any obvious influence by antithrombin on brain injury progress, on CT, or on outcome or time needed for intensive care.

ISSN:0898-4921    

出版商:OVID    

年代:2001

数据来源: OVID