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1.
J Neurosurg ; : 1-8, 2019 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-31151110

RESUMO

OBJECTIVE: Delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) may result in focal neurological deficits and cerebral infarction, believed to result from critical regional rather than global impairments in cerebral blood flow (CBF). However, the burden of such regional hypoperfusion has not been evaluated by gold-standard voxel-by-voxel CBF measurements. Specifically, the authors sought to determine whether the proportion of brain affected by hypoperfusion was greater in patients with DCI than in SAH controls without DCI and whether the symptomatic hemisphere (in those with lateralizing deficits) exhibited a greater cerebral hypoperfusion burden. METHODS: Sixty-one patients with aneurysmal SAH underwent 15O PET to measure regional CBF during the period of risk for DCI (median 8 days after SAH, IQR 7-10 days). Regions of visibly abnormal brain on head CT studies, including areas of hemorrhage and infarction, were excluded. Burden of hypoperfusion was defined as the proportion of PET voxels in normal-appearing brain with CBF < 25 ml/100 g/min. Global CBF and hypoperfusion burden were compared between patients with and those without DCI at the time of PET. For patients with focal impairments from DCI, the authors also compared average CBF and hypoperfusion burden in symptomatic versus asymptomatic hemispheres. RESULTS: Twenty-three patients (38%) had clinical DCI at the time of PET. Those with DCI had higher mean arterial pressure (MAP; 126 ± 14 vs 106 ± 12 mm Hg, p < 0.001) and 18 (78%) were on vasopressor therapy at the time of PET study. While global CBF was not significantly lower in patients with DCI (mean 39.4 ± 11.2 vs 43.0 ± 8.3 ml/100 g/min, p = 0.16), the burden of hypoperfusion was greater (20%, IQR 12%-23%, vs 12%, 9%-16%, p = 0.006). Burden of hypoperfusion performed better than global CBF as a predictor of DCI (area under the curve 0.71 vs 0.65, p = 0.044). Neither global CBF nor hypoperfusion burden differed in patients who responded to therapy compared to those who had not improved by the time of PET. Although hemispheric CBF was not lower in the symptomatic versus contralateral hemisphere in the 13 patients with focal deficits, there was a trend toward greater burden of hypoperfusion in the symptomatic hemisphere (21% vs 18%, p = 0.049). CONCLUSIONS: The burden of hypoperfusion was greater in patients with DCI, despite hemodynamic therapies, higher MAP, and equivalent global CBF. Similarly, hypoperfusion burden was greater in the symptomatic hemisphere of DCI patients with focal deficits even though the average CBF was similar to that in the contralateral hemisphere. Evaluating the proportion of the brain with critical hypoperfusion after SAH may better capture the extent of DCI than averaging CBF across heterogenous brain regions.

2.
Lancet Neurol ; 17(10): 885-894, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30120039

RESUMO

BACKGROUND: Intracerebral haemorrhage growth is associated with poor clinical outcome and is a therapeutic target for improving outcome. We aimed to determine the absolute risk and predictors of intracerebral haemorrhage growth, develop and validate prediction models, and evaluate the added value of CT angiography. METHODS: In a systematic review of OVID MEDLINE-with additional hand-searching of relevant studies' bibliographies- from Jan 1, 1970, to Dec 31, 2015, we identified observational cohorts and randomised trials with repeat scanning protocols that included at least ten patients with acute intracerebral haemorrhage. We sought individual patient-level data from corresponding authors for patients aged 18 years or older with data available from brain imaging initially done 0·5-24 h and repeated fewer than 6 days after symptom onset, who had baseline intracerebral haemorrhage volume of less than 150 mL, and did not undergo acute treatment that might reduce intracerebral haemorrhage volume. We estimated the absolute risk and predictors of the primary outcome of intracerebral haemorrhage growth (defined as >6 mL increase in intracerebral haemorrhage volume on repeat imaging) using multivariable logistic regression models in development and validation cohorts in four subgroups of patients, using a hierarchical approach: patients not taking anticoagulant therapy at intracerebral haemorrhage onset (who constituted the largest subgroup), patients taking anticoagulant therapy at intracerebral haemorrhage onset, patients from cohorts that included at least some patients taking anticoagulant therapy at intracerebral haemorrhage onset, and patients for whom both information about anticoagulant therapy at intracerebral haemorrhage onset and spot sign on acute CT angiography were known. FINDINGS: Of 4191 studies identified, 77 were eligible for inclusion. Overall, 36 (47%) cohorts provided data on 5435 eligible patients. 5076 of these patients were not taking anticoagulant therapy at symptom onset (median age 67 years, IQR 56-76), of whom 1009 (20%) had intracerebral haemorrhage growth. Multivariable models of patients with data on antiplatelet therapy use, data on anticoagulant therapy use, and assessment of CT angiography spot sign at symptom onset showed that time from symptom onset to baseline imaging (odds ratio 0·50, 95% CI 0·36-0·70; p<0·0001), intracerebral haemorrhage volume on baseline imaging (7·18, 4·46-11·60; p<0·0001), antiplatelet use (1·68, 1·06-2·66; p=0·026), and anticoagulant use (3·48, 1·96-6·16; p<0·0001) were independent predictors of intracerebral haemorrhage growth (C-index 0·78, 95% CI 0·75-0·82). Addition of CT angiography spot sign (odds ratio 4·46, 95% CI 2·95-6·75; p<0·0001) to the model increased the C-index by 0·05 (95% CI 0·03-0·07). INTERPRETATION: In this large patient-level meta-analysis, models using four or five predictors had acceptable to good discrimination. These models could inform the location and frequency of observations on patients in clinical practice, explain treatment effects in prior randomised trials, and guide the design of future trials. FUNDING: UK Medical Research Council and British Heart Foundation.

3.
Neurocrit Care ; 29(2): 225-232, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29637518

RESUMO

BACKGROUND: Cerebrovascular events (CVE) are among the most common and serious complications after implantation of continuous-flow left ventricular assist devices (CF-LVAD). We studied the incidence, subtypes, anatomical distribution, and pre- and post-implantation risk factors of CVEs as well as the effect of CVEs on outcomes after CF-LVAD implantation at our institution. METHODS: Retrospective analysis of clinical and neuroimaging data of 372 patients with CF-LVAD between May 2005 and December 2013 using standard statistical methods. RESULTS: CVEs occurred in 71 patients (19%), consisting of 35 ischemic (49%), 26 hemorrhagic (37%), and 10 ischemic+hemorrhagic (14%) events. History of coronary artery disease and female gender was associated with higher odds of ischemic CVE (OR 2.84 and 2.5, respectively), and diabetes mellitus was associated with higher odds of hemorrhagic CVE (OR 3.12). While we found a higher rate of ischemic CVEs in patients not taking any antithrombotic medications, no difference was found between patients with ischemic and hemorrhagic CVEs. Occurrence of CVEs was associated with increased mortality (HR 1.62). Heart transplantation was associated with improved survival (HR 0.02). In patients without heart transplantation, occurrence of CVE was associated with decreased survival. CONCLUSIONS: LVADs are associated with high rates of CVE, increased mortality, and lower rates of heart transplantation. Further investigations to identify the optimal primary and secondary stroke prevention measures in post-LVAD patients are warranted.

4.
Neurology ; 90(7): e632-e636, 2018 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-29352100

RESUMO

OBJECTIVE: To determine the relationship between neurology inpatient satisfaction and (1) number of physicians involved in the patient's care and (2) patients' ability to identify their physicians. METHODS: A 10-item questionnaire addressing patient satisfaction and identification of physicians on the care team was administered to patients admitted to an academic, tertiary care, inpatient neurology service from May 1 to October 31, 2012. We hypothesized higher satisfaction among patients having fewer physicians on the care team and among patients able to identify their physicians. RESULTS: A total of 652 patients were enrolled. An average of 3.9 (range 3-8) physicians were involved in each patient's care. Patients were able to correctly identify on average 2.4 (60.7%) physicians involved in their care. Patients who were very satisfied correctly identified a larger percentage of physicians involved in their care (63.8% vs 50.7%, p < 0.001), were more likely to identify a physician who knew them best (94.3% vs 43.6%, p < 0.001) and who was "in charge" of their care (94.1% vs 57.6%, p < 0.001), and were more likely to have private insurance (82.8% vs 70.5%, p < 0.001) and fewer physicians involved in their care (3.84 vs 4.06, p = 0.02). CONCLUSIONS: Neurology inpatients' ability to identify physicians involved in their care is associated with patient satisfaction. Strategies to enhance patient satisfaction might target improving physician identification, reducing actual or perceived disparities in care based on payer status, and reducing handoffs or conducting handoffs at the bedside.

5.
Semin Respir Crit Care Med ; 38(6): 760-767, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-29262433

RESUMO

This article addresses the intensive care unit (ICU) management of patients with aneurysmal subarachnoid hemorrhage (SAH), with an emphasis on the prevention of cerebral vasospasm and delayed cerebral ischemia (DCI), which are major contributors to morbidity and mortality. Interventions addressing various steps in the development of vasospasm have been attempted, with variable success. Enteral nimodipine remains the only approved measure to potentially prevent DCI. Since oral and intravenous administrations are limited by hypotension, direct administration via sustained-release pellets and intraventricular administration of sustained-release microparticles are being investigated. Studies of other calcium channel blockers have been disappointing. Efforts to remove blood from the subarachnoid space via cisternal irrigation, cisternal or ventricular thrombolysis, and lumbar cerebrospinal fluid drainage have met with limited and variable success, and they remain an area of active investigation. Several interventions that had early promise have failed to show benefit when studied in large trials; these include tirilazad, magnesium, statins, clazosentan, transluminal angioplasty, and hypervolemia.


Assuntos
Aneurisma Intracraniano/terapia , Hemorragia Subaracnóidea/terapia , Vasoespasmo Intracraniano/prevenção & controle , Bloqueadores dos Canais de Cálcio/administração & dosagem , Bloqueadores dos Canais de Cálcio/uso terapêutico , Preparações de Ação Retardada , Humanos , Unidades de Terapia Intensiva , Aneurisma Intracraniano/complicações , Nimodipina/administração & dosagem , Nimodipina/uso terapêutico , Hemorragia Subaracnóidea/complicações , Vasoespasmo Intracraniano/etiologia
6.
Stroke ; 48(4): 894-899, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28283605

RESUMO

BACKGROUND AND PURPOSE: The purpose was to test the hypothesis that increased oxygen extraction fraction (OEF), a marker of severe hemodynamic impairment measured by positron emission tomography, is an independent risk factor for subsequent ischemic stroke in this population. METHODS: Adults with idiopathic moyamoya phenomena were recruited between 2005 and 2012 for a prospective, multicenter, blindly adjudicated, longitudinal cohort study. Measurements of OEF were obtained on enrollment. Subjects were followed up for the occurrence of ipsilateral ischemic stroke at 6-month intervals. Patients were censored at the time of surgical revascularization or at last follow-up. The primary analysis was time to ischemic stroke in the territory of the occlusive vasculopathy. RESULTS: Forty-nine subjects were followed up during a median of 3.7 years. One of 16 patients with increased OEF on enrollment had an ischemic stroke and another had an intraparenchymal hemorrhage. Three of 33 patients with normal OEF had an ischemic stroke. On a per-hemisphere basis, 21 of 79 hemispheres with moyamoya vasculopathy had increased OEF at baseline. No ischemic strokes and one hemorrhage occurred in a hemisphere with increased OEF (n=21). Sixteen patients (20 hemispheres), including 5 with increased OEF at enrollment, were censored at a mean of 5.3 months after enrollment for revascularization surgery. CONCLUSIONS: The risk of new or recurrent stroke was lower than expected. The low event rate, low prevalence of increased OEF, and potential selection bias introduced by revascularization surgery limit strong conclusions about the association of increased OEF and future stroke risk. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00629915.


Assuntos
Isquemia Encefálica/diagnóstico por imagem , Doença de Moyamoya/diagnóstico por imagem , Acoplamento Neurovascular , Tomografia por Emissão de Pósitrons/métodos , Acidente Vascular Cerebral/diagnóstico por imagem , Adulto , Idoso , Isquemia Encefálica/epidemiologia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Meio-Oeste dos Estados Unidos/epidemiologia , Doença de Moyamoya/epidemiologia , Oxigênio/metabolismo , Recidiva , Fatores de Risco , Método Simples-Cego , Acidente Vascular Cerebral/epidemiologia
7.
Circulation ; 135(10): e604-e633, 2017 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-28167634

RESUMO

Non-vitamin K oral anticoagulants (NOACs) are now widely used as alternatives to warfarin for stroke prevention in atrial fibrillation and management of venous thromboembolism. In clinical practice, there is still widespread uncertainty on how to manage patients on NOACs who bleed or who are at risk for bleeding. Clinical trial data related to NOAC reversal for bleeding and perioperative management are sparse, and recommendations are largely derived from expert opinion. Knowledge of time of last ingestion of the NOAC and renal function is critical to managing these patients given that laboratory measurement is challenging because of the lack of commercially available assays in the United States. Idarucizumab is available as an antidote to rapidly reverse the effects of dabigatran. At present, there is no specific antidote available in the United States for the oral factor Xa inhibitors. Prothrombin concentrate may be considered in life-threatening bleeding. Healthcare institutions should adopt a NOAC reversal and perioperative management protocol developed with multidisciplinary input.


Assuntos
Anticoagulantes/uso terapêutico , Fibrilação Atrial/tratamento farmacológico , Tromboembolia Venosa/tratamento farmacológico , American Heart Association , Anticorpos Monoclonais Humanizados/uso terapêutico , Antídotos/uso terapêutico , Dabigatrana/uso terapêutico , Hemorragia/prevenção & controle , Humanos , Estados Unidos
8.
Crit Care Med ; 45(4): 653-659, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28169942

RESUMO

OBJECTIVES: Impaired oxygen delivery due to reduced cerebral blood flow is the hallmark of delayed cerebral ischemia following subarachnoid hemorrhage. Since anemia reduces arterial oxygen content, it further threatens oxygen delivery increasing the risk of cerebral infarction. Thus, subarachnoid hemorrhage may constitute an important exception to current restrictive transfusion practices, wherein raising hemoglobin could reduce the risk of ischemia in a critically hypoperfused organ. In this physiologic proof-of-principle study, we determined whether transfusion could augment cerebral oxygen delivery, particularly in vulnerable brain regions, across a broad range of hemoglobin values. DESIGN: Prospective study measuring cerebral blood flow and oxygen extraction fraction using O-PET. Vulnerable brain regions were defined as those with baseline oxygen delivery less than 4.5 mL/100 g/min. SETTING: PET facility located within the Neurology/Neurosurgery ICU. PATIENTS: Fifty-two patients at risk for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage with hemoglobin 7-13 g/dL. INTERVENTIONS: Transfusion of one unit of RBCs over 1 hour. MEASUREMENTS AND MAIN RESULTS: Baseline hemoglobin was 9.7 g/dL (range, 6.9-12.9), and cerebral blood flow was 43 ± 11 mL/100 g/min. After transfusion, hemoglobin rose from 9.6 ± 1.4 to 10.8 ± 1.4 g/dL (12%; p < 0.001) and oxygen delivery from 5.0 (interquartile range, 4.4-6.6) to 5.5 mL/100 g/min (interquartile range, 4.8-7.0) (10%; p = 0.001); the response was comparable across the range of hemoglobin values. In vulnerable brain regions, transfusion resulted in a greater (16%) rise in oxygen delivery associated with reduction in oxygen extraction fraction, independent of Hgb level (p = 0.002 vs normal regions). CONCLUSIONS: This study demonstrates that RBC transfusion improves cerebral oxygen delivery globally and particularly to vulnerable regions in subarachnoid hemorrhage patients at risk for delayed cerebral ischemia across a wide range of hemoglobin values and suggests that restrictive transfusion practices may not be appropriate in this population. Large prospective trials are necessary to determine if these physiologic benefits translate into clinical improvement and outweigh the risk of transfusion.


Assuntos
Infarto Cerebral/prevenção & controle , Transfusão de Eritrócitos , Hemoglobinas/metabolismo , Oxigênio/sangue , Hemorragia Subaracnóidea/fisiopatologia , Hemorragia Subaracnóidea/terapia , Idoso , Infarto Cerebral/sangue , Infarto Cerebral/etiologia , Circulação Cerebrovascular , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons , Estudos Prospectivos , Hemorragia Subaracnóidea/complicações
9.
Neurocrit Care ; 25(1): 56-63, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-26721259

RESUMO

BACKGROUND: Statins may promote vasodilation following subarachnoid hemorrhage (SAH) and improve the response to blood pressure elevation. We sought to determine whether simvastatin increases cerebral blood flow (CBF) and alters the response to induced hypertension after SAH. METHODS: Statin-naïve patients admitted <72 h after WFNS ≥2 aneurysmal SAH were randomly assigned to 80 mg simvastatin/day or placebo for 21 days. Regional CBF was measured with quantitative (15)O PET on SAH day 7-10 before and after raising mean arterial pressure (MAP) 20-25 %. Autoregulatory index (AI) was calculated as the ratio of % change in resistance (MAP/CBF) to % change in MAP. Angiography was performed within 24 h of PET. Results are presented as simvastatin vs. placebo. RESULTS: Thirteen patients received simvastatin and 12 placebo. Clinical characteristics were similar. Moderate or severe angiographic vasospasm occurred in 42 vs. 45 % and delayed cerebral ischemia in 14 vs. 55 % (p = 0.074). During PET studies, MAP (110 ± 10 vs. 111 ± 12), global CBF (41 ± 12 vs. 43 ± 13), and CVR (2.95 ± 1.0 vs. 2.81 ± 1.0) did not differ at baseline. When MAP was raised to 135 ± 7 mm Hg vs. 137 ± 15, global CBF did not change. Global AI did not differ (107 ± 59 vs. 0. 89 ± 52 %, p = 0.68). CBF did not change in regions with low baseline flow or in regions supplied by vessels with angiographic vasospasm in either group. Six-month modified Rankin Scale scores did not differ. CONCLUSIONS: Our data indicate that initiation of therapy with high-dose simvastatin does not alter baseline CBF or response to induced hypertension.


Assuntos
Isquemia Encefálica/prevenção & controle , Circulação Cerebrovascular/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Sinvastatina/farmacologia , Hemorragia Subaracnóidea/tratamento farmacológico , Vasoespasmo Intracraniano/prevenção & controle , Idoso , Isquemia Encefálica/diagnóstico por imagem , Feminino , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/administração & dosagem , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons , Sinvastatina/administração & dosagem , Hemorragia Subaracnóidea/diagnóstico por imagem , Vasoespasmo Intracraniano/diagnóstico por imagem
10.
Teach Learn Med ; 26(4): 327-34, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25318026

RESUMO

BACKGROUND: Technological advances have diminished reliance on classroom attendance for mastering preclinical medical school course content, but nonattendance may have unintended consequence on the learning environment. Perceptions among educators and students regarding the value of attendance and implications of nonattendance have not been systematically studied. PURPOSES: The purpose of this study was to investigate differences in medical student and faculty attitudes regarding preclinical classroom attendance and the impact of nonattendance on educators and the learning environment. METHODS: Using Internet-based surveys, we assessed attitudes about preclinical classroom attendance among medical students and teaching faculty at Washington University School of Medicine. Our primary hypothesis was that students would be less likely than faculty to place societal value on attendance and relate it to professionalism. RESULTS: A total of 382 (79%) of 484 eligible students and 248 (64%) of 387 eligible faculty completed the survey. Both groups recognized a negative impact of poor attendance on faculty enthusiasm for teaching (students 83%, faculty 75%), but faculty were significantly more likely to endorse a negative impact on effectiveness of lectures (75% vs. 42%, p<.0001) and small-groups (92% vs. 76%, p<.0001) and a relationship between attendance and professionalism (88% vs. 68%, p<.0001). Students were significantly more likely to support free choice among learning opportunities (90% vs. 41%, p<.0001) including regularly missing class for research and community service activities (70% vs. 14%, p<.0001) and to consider lecture videos an adequate substitute for attendance (70% vs. 15%, p<.0001). Free-text responses suggested that students tended to view class-going primarily as a tool for learning factual material, whereas many faculty viewed it as serving important functions in the professional socialization process. CONCLUSIONS: In this single-center cohort, medical student and teaching faculty attitudes differed regarding the importance of classroom attendance and its relationship to professionalism, findings that were at least partially explained by differing expectations of the purpose of the preclinical classroom experience.


Assuntos
Absenteísmo , Atitude , Educação de Graduação em Medicina , Docentes de Medicina , Estudantes de Medicina/psicologia , Feminino , Humanos , Masculino , Inquéritos e Questionários
11.
J Neurosurg ; 118(1): 34-41, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23061393

RESUMO

OBJECT: The aim of this study was to define the optimal treatment for patients with symptomatic intraluminal carotid artery thrombus (ICAT). METHODS: The authors performed a retrospective chart review of patients who had presented with symptomatic ICAT at their institution between 2001 and 2011. RESULTS: Twenty-four patients (16 males and 8 females) with ICAT presented with ischemic stroke (18 patients) or transient ischemic attack ([TIA], 6 patients). All were initially treated using anticoagulation with or without antiplatelet drugs. Eight of these patients had no or only mild carotid artery stenosis on initial angiography and were treated with medical management alone. The remaining 16 patients had moderate or severe carotid stenosis on initial angiography; of these, 10 underwent delayed revascularization (8 patients, carotid endarterectomy [CEA]; 2 patients, angioplasty and stenting), 2 refused revascularization, and 4 were treated with medical therapy alone. One patient had multiple TIAs despite medical therapy and eventually underwent CEA; the remaining 23 patients had no TIAs after treatment. No patient suffered ischemic or hemorrhagic stroke while on anticoagulation therapy, either during the perioperative period or in the long-term follow-up; 1 patient died of an unrelated condition. The mean follow-up was 16.4 months. CONCLUSIONS: Results of this study suggest that initial anticoagulation for symptomatic ICAT leads to a low rate of recurrent ischemic events and that carotid revascularization, if indicated, can be safely performed in a delayed manner.


Assuntos
Isquemia Encefálica/terapia , Artérias Carótidas/cirurgia , Trombose das Artérias Carótidas/terapia , Estenose das Carótidas/terapia , Acidente Vascular Cerebral/terapia , Adulto , Idoso , Anticoagulantes/uso terapêutico , Aspirina/uso terapêutico , Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/tratamento farmacológico , Isquemia Encefálica/cirurgia , Artérias Carótidas/diagnóstico por imagem , Trombose das Artérias Carótidas/diagnóstico por imagem , Trombose das Artérias Carótidas/tratamento farmacológico , Trombose das Artérias Carótidas/cirurgia , Estenose das Carótidas/diagnóstico por imagem , Estenose das Carótidas/tratamento farmacológico , Estenose das Carótidas/cirurgia , Angiografia Cerebral , Endarterectomia das Carótidas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inibidores da Agregação de Plaquetas/uso terapêutico , Estudos Retrospectivos , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/tratamento farmacológico , Acidente Vascular Cerebral/cirurgia , Resultado do Tratamento , Varfarina/uso terapêutico
13.
Stroke ; 43(7): 1788-94, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22492520

RESUMO

BACKGROUND AND PURPOSE: Angiographic vasospasm frequently complicates subarachnoid hemorrhage and has been implicated in the development of delayed cerebral ischemia. Whether large-vessel narrowing adequately accounts for the critical reductions in regional cerebral blood flow underlying ischemia is unclear. We sought to clarify the relationship between angiographic vasospasm and regional hypoperfusion. METHODS: Twenty-five patients with aneurysmal subarachnoid hemorrhage underwent cerebral catheter angiography and 15O-positron emission tomographic imaging within 1 day of each other (median of 7 days after subarachnoid hemorrhage). Severity of vasospasm was assessed in each intracranial artery, whereas cerebral blood flow and oxygen extraction fraction were measured in 28 brain regions distributed across these vascular territories. We analyzed the association between vasospasm and perfusion and compared frequency of hypoperfusion (cerebral blood flow<25 mL/100 g/min) and oligemia (low oxygen delivery with oxygen extraction fraction≥0.5) in territories with versus without significant vasospasm. RESULTS: Twenty-four percent of 652 brain regions were supplied by vessels with significant vasospasm. Cerebral blood flow was lower in such regions (38.6±12 versus 48.7±16 mL/100 g/min), whereas oxygen extraction fraction was higher (0.48±0.19 versus 0.37±0.14, both P<0.001). Hypoperfusion was seen in 46 regions (7%), but 66% of these were supplied by vessels with no significant vasospasm; 24% occurred in patients without angiographic vasospasm. Similarly, oligemia occurred more frequently outside territories with vasospasm. CONCLUSIONS: Angiographic vasospasm is associated with reductions in cerebral perfusion. However, regional hypoperfusion and oligemia frequently occurred in territories and patients without vasospasm. Other factors in addition to large-vessel narrowing must contribute to critical reductions in perfusion.


Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Angiografia Cerebral , Circulação Cerebrovascular/fisiologia , Hemorragia Subaracnóidea/diagnóstico por imagem , Vasoespasmo Intracraniano/diagnóstico por imagem , Idoso , Angiografia Cerebral/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons/métodos , Estudos Retrospectivos , Hemorragia Subaracnóidea/fisiopatologia , Vasoespasmo Intracraniano/fisiopatologia
14.
J Neurosurg ; 116(3): 648-56, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22098203

RESUMO

OBJECT: Critical reductions in oxygen delivery (DO(2)) underlie the development of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH). If DO(2) is not promptly restored, then irreversible injury (that is, cerebral infarction) may result. Hemodynamic therapies for DCI (that is, induced hypertension [IH] and hypervolemia) aim to improve DO(2) by raising cerebral blood flow (CBF). Red blood cell (RBC) transfusion may be an alternate strategy that augments DO(2) by improving arterial O(2) content. The authors compared the relative ability of these 3 interventions to improve cerebral DO(2), specifically their ability to restore DO(2) to regions where it is impaired. METHODS: The authors compared 3 prospective physiological studies in which PET imaging was used to measure global and regional CBF and DO(2) before and after the following treatments: 1) fluid bolus of 15 ml/kg normal saline (9 patients); 2) raising mean arterial pressure 25% (12 patients); and 3) transfusing 1 U of RBCs (17 patients) in 38 individuals with aneurysmal SAH at risk for DCI. Response between groups in regions with low DO(2) (< 4.5 ml/100 g/min) was compared using repeated-measures ANOVA. RESULTS: Groups were similar except that the fluid bolus cohort had more patients with symptoms of DCI and lower baseline CBF. Global CBF or DO(2) did not rise significantly after any of the interventions, except after transfusion in patients with hemoglobin levels < 9 g/dl. All 3 treatments improved CBF and DO(2) to regions with impaired baseline DO(2), with a greater improvement after transfusion (23%) than hypertension (14%) or volume loading (10%); p < 0.001. Transfusion also resulted in a nonsignificantly greater (47%) reduction in the number of brain regions with low DO(2) when compared with fluid bolus (7%) and hypertension (12%) (p = 0.33). CONCLUSIONS: The IH, fluid bolus, and blood transfusion interventions all improve DO(2) to vulnerable brain regions at risk for ischemia after SAH. Transfusion appeared to provide a physiological benefit at least comparable to IH, especially among patients with anemia, but transfusion is associated with risks. The clinical significance of these findings remains to be established in controlled clinical trials.


Assuntos
Infarto Cerebral/prevenção & controle , Transfusão de Eritrócitos/métodos , Hipertensão/induzido quimicamente , Cloreto de Sódio/administração & dosagem , Hemorragia Subaracnóidea/complicações , Idoso , Isquemia Encefálica/complicações , Isquemia Encefálica/etiologia , Infarto Cerebral/etiologia , Circulação Cerebrovascular/fisiologia , Estudos de Coortes , Transfusão de Eritrócitos/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Oxigênio/sangue , Tomografia por Emissão de Pósitrons , Estudos Prospectivos , Hemorragia Subaracnóidea/fisiopatologia
15.
J Crit Care ; 27(5): 526.e7-12, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22176808

RESUMO

PURPOSE: Cerebral blood flow (CBF) is reduced after severe traumatic brain injury (TBI) with considerable regional variation. Osmotic agents are used to reduce elevated intracranial pressure (ICP), improve cerebral perfusion pressure, and presumably improve CBF. Yet, osmotic agents have other physiologic effects that can influence CBF. We sought to determine the regional effect of osmotic agents on CBF when administered to treat intracranial hypertension. MATERIALS AND METHODS: In 8 patients with acute TBI, we measured regional CBF with positron emission tomography before and 1 hour after administration of equi-osmolar 20% mannitol (1 g/kg) or 23.4% hypertonic saline (0.686 mL/kg) in regions with focal injury and baseline hypoperfusion (CBF <25 mL per 100 g/min). RESULTS: The ICP fell (22.4 ± 5.1 to 15.7 ± 7.2 mm Hg, P = .007), and cerebral perfusion pressure rose (75.7 ± 5.9 to 81.9 ± 10.3 mm Hg, P = .03). Global CBF tended to rise (30.9 ± 3.7 to 33.1 ± 4.2 mL per 100 g/min, P = .07). In regions with focal injury, baseline flow was 25.7 ± 9.1 mL per 100 g/min and was unchanged; in hypoperfused regions (15% of regions), flow rose from 18.6 ± 5.0 to 22.4 ± 6.4 mL per 100 g/min (P < .001). Osmotic therapy reduced the number of hypoperfused brain regions by 40% (P < .001). CONCLUSION: Osmotic agents, in addition to lowering ICP, improve CBF to hypoperfused brain regions in patients with intracranial hypertension after TBI.


Assuntos
Lesões Encefálicas/tratamento farmacológico , Circulação Cerebrovascular/efeitos dos fármacos , Diuréticos Osmóticos/uso terapêutico , Pressão Intracraniana/efeitos dos fármacos , Manitol/uso terapêutico , Solução Salina Hipertônica/uso terapêutico , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tomografia por Emissão de Pósitrons
16.
Neurosurgery ; 70(5): 1215-8; discussion 1219, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22089753

RESUMO

BACKGROUND: Mannitol has traditionally been the mainstay of medical therapy for intracranial hypertension in patients with head injury. We previously demonstrated that mannitol reduces brain volume in patients with cerebral edema, although whether this occurs because of a reduction in brain water, blood volume, or both remains poorly understood. OBJECTIVE: To test the hypothesis that mannitol acts by lowering blood viscosity leading to reflex vasoconstriction and a fall in cerebral blood volume (CBV). METHODS: We used O positron emission tomography to study 6 patients with traumatic brain injuries requiring treatment for intracranial hypertension. Cerebral blood flow (CBF), CBV, and cerebral metabolic rate for oxygen (CMRO2) were measured before and 1 hour after administration of 1.0 g/kg 20% mannitol. RESULTS: CBV rose from 4.1 ± 0.4 to 4.2 ± 0.2 mL/100 g (P = .3), while intracranial pressure fell from 21.5 ± 4.9 to 13.7 ± 5.1 mm Hg (P < .003) after mannitol. Blood pressure, PaCO2, oxygen content, CBF, and CMRO2 did not change. CONCLUSION: A single bolus of 1 g/kg of 20% mannitol does not acutely lower CBV. Another mechanism, such as a reduction in brain water, may better explain mannitol's ability to lower intracranial pressure and reduce mass effect.


Assuntos
Volume Sanguíneo/efeitos dos fármacos , Traumatismos Craniocerebrais/tratamento farmacológico , Traumatismos Craniocerebrais/fisiopatologia , Hipertensão Intracraniana/tratamento farmacológico , Hipertensão Intracraniana/fisiopatologia , Manitol/administração & dosagem , Adulto , Viscosidade Sanguínea/efeitos dos fármacos , Traumatismos Craniocerebrais/complicações , Diuréticos Osmóticos/administração & dosagem , Humanos , Hipertensão Intracraniana/etiologia , Masculino , Resultado do Tratamento , Vasoconstrição/efeitos dos fármacos
17.
Neurocrit Care ; 15(3): 436-41, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21725692

RESUMO

BACKGROUND AND PURPOSE: The perihematomal hyperintensity (PHH) is commonly interpreted to represent cerebral edema following intracerebral hemorrhage (ICH), but the accuracy of this interpretation is unknown. We therefore investigated the relationship between the changes in PHH and the changes in hemispheric brain volume as a measure of edema during the first week after ICH. METHODS: Fifteen individuals aged 66 ± 13 with baseline hematoma size of 13.1 ml (range 3-43) were prospectively studied with sequential MRI 1.0 ± 0.5, 2.6 ± 0.9, and 6.5 ± 1.0 days after spontaneous supratentorial ICH. Changes in hemispheric brain volume were assessed on MPRAGE using the Brain-Boundary Shift Integral (BBSI). Hematoma and PHH volumes were measured on T2-weighted images. RESULTS: Brain volume increased a small but statistically significant amount (6.3 ± 8.0 ml, 0.6 ± 0.7%) between the first and second scans relative to 10 normal controls (-0.9 ± 4.1 ml, P = 0.02) and returned toward baseline at the third scan (1.5 ± 9.5 ml vs. controls 0.9 ± 4.0 ml, P = 0.85). There were no significant differences in the volume changes between the two hemispheres at scan 2 or scan 3. At both scan 2 (P = 0.04) and scan 3 (P = 0.004), the change in PHH was significantly greater than and poorly correlated with the change in ipsilateral hemispheric volume. There were no significant correlations between the change in NIH Stroke Scale (NIHSS) and the change in PHH, ipsilateral, or total brain volume at scan 2 or scan 3 (all P > 0.05). CONCLUSIONS: In patients with small-to-moderate-sized hematomas, change in PHH was a poor measure of brain edema in the first week following ICH. A small degree of bihemispheric brain swelling occurred, but was of little clinical significance.


Assuntos
Edema Encefálico/diagnóstico , Hemorragia Cerebral/diagnóstico , Hematoma/diagnóstico , Interpretação de Imagem Assistida por Computador , Imagem por Ressonância Magnética , Adulto , Edema Encefálico/fisiopatologia , Hemorragia Cerebral/fisiopatologia , Estado Terminal , Dominância Cerebral/fisiologia , Feminino , Escala de Coma de Glasgow , Hematoma/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Tamanho do Órgão/fisiologia , Valores de Referência , Estatística como Assunto , Tomografia Computadorizada por Raios X
18.
Am J Occup Ther ; 65(3): 306-13, 2011 May-Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21675336

RESUMO

OBJECTIVE: We investigated participation levels and relationships among cognition, depression, and participation for people with severe congestive heart failure (CHF). METHOD: People with severe CHF (New York Heart Association Class III or IV) awaiting heart transplantation (N = 27) completed standardized tests of cognition and self-report measures of executive dysfunction, depressive symptoms, and participation. RESULTS: Possible depression (64%) and cognitive impairment (15%-59%) were prevalent. Participants reported significant reductions in participation across all activity domains since CHF diagnosis (ps < .001). Worse executive dysfunction and depressive symptoms were associated with reduced participation and together accounted for 35%-46% of the variance in participation (ps < .01). CONCLUSION: Participation restrictions associated with CHF are not limited to physically demanding activities and are significantly associated with executive dysfunction and depression. Cardiac rehabilitation should address cognitive and psychological functioning in the context of all life situations instead of focusing solely on physical function and disability.


Assuntos
Depressão/epidemiologia , Depressão/psicologia , Função Executiva , Insuficiência Cardíaca/psicologia , Participação Social , Adulto , Transtornos Cognitivos/complicações , Transtornos Cognitivos/epidemiologia , Transtornos Cognitivos/psicologia , Estudos Transversais , Depressão/complicações , Feminino , Insuficiência Cardíaca/complicações , Humanos , Masculino , Registros Médicos , Pessoa de Meia-Idade , Missouri/epidemiologia , Escalas de Graduação Psiquiátrica , Adulto Jovem
19.
Transl Stroke Res ; 2(4): 517-23, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24323682

RESUMO

Ischemia has long been regarded as a cause of secondary brain injury following severe traumatic brain injury (TBI). This manuscript will present the viewpoint that, except for cases of extremely low cerebral perfusion pressure, efforts to establish the presence of ischemia in TBI patients using a variety of techniques have been inconclusive. Early studies found that cerebral blood flow (CBF) was low in acute TBI patients, suggesting ischemia. However, CBF can be low but adequate to meet tissue energy needs in the presence of a low cerebral metabolic rate; so in such situations, measurement of blood flow, metabolism and oxygen update are necessary to detect ischemia. There is little doubt that ischemia occurs in severe TBI when cerebral oxygen delivery is markedly compromised, however, the role of ischemia outside of this extreme remains unresolved at present. Early after injury, global blood flow, metabolism, and oxygen extraction are reduced suggesting suppressed metabolism rather than active ischemia. Multiple factors including over excitation, calcium influx, and oxidative stress, and hyperacute ischemia may contribute to this process, but evidence of ongoing ischemic injury is mixed. Data from microdialysis probes provide differing results depending on what is measured and how it is interpreted and yield results that are inconsistent with brain tissue oxygen tension data. PET studies, depending on how they are analyzed and the thresholds used, indicate either no ischemia or a small volume of ischemic brain.

20.
Neurocrit Care ; 14(1): 11-7, 2011 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21042881

RESUMO

INTRODUCTION: Cerebral edema after ischemic stroke is frequently treated with mannitol and hypertonic saline (HS); however, their relative cerebrovascular and metabolic effects are incompletely understood, and may operate independent of their ability to lower intracranial pressure. METHODS: We compared the effects of 20% mannitol and 23.4% saline on cerebral blood flow (CBF), blood volume (CBV), oxygen extraction fraction (OEF), and oxygen metabolism (CMRO(2)), in nine ischemic stroke patients who deteriorated and had >2 mm midline shift on imaging. (15)O-PET was performed before and 1 h after administration of randomly assigned equi-osmolar doses of mannitol (1.0 g/kg) or 23.4% saline (0.686 mL/kg). RESULTS: Baseline CBF values (ml/100g/min) in the infarct core, periinfarct region, remaining ipsilateral hemisphere, and contralateral hemisphere in the mannitol group were 5.0 ± 3.9, 25.6 ± 4.4, 35.6 ± 8.6, and 45.5 ± 2.2, respectively, and in the HS group were 8.3 ± 9.8, 35.3 ± 10.9, 38.2 ± 15.1, and 35.2 ± 12.4, respectively. There was a trend for CBF to rise in the contralateral hemisphere after mannitol from 45.5 ± 12.2 to 57.6 ± 21.7, P = 0.098, but not HS. CBV, OEF, and CMRO(2) did not change after administration of either agent. Change in CBF in the contralateral hemisphere after osmotic therapy was strongly correlated with baseline blood pressure (R (2)= 0.879, P = 0.002). CONCLUSIONS: We conclude that at higher perfusion pressures, osmotic agents may raise CBF in non-ischemic tissue. We conclude that at higher perfusion pressures, osmotic agents may raise CBF in non-ischemic tissue.


Assuntos
Edema Encefálico/tratamento farmacológico , Isquemia Encefálica/tratamento farmacológico , Diuréticos Osmóticos/administração & dosagem , Manitol/administração & dosagem , Solução Salina Hipertônica/administração & dosagem , Acidente Vascular Cerebral/tratamento farmacológico , Idoso , Pressão Sanguínea/efeitos dos fármacos , Volume Sanguíneo/efeitos dos fármacos , Edema Encefálico/metabolismo , Edema Encefálico/fisiopatologia , Isquemia Encefálica/metabolismo , Isquemia Encefálica/fisiopatologia , Circulação Cerebrovascular/efeitos dos fármacos , Cuidados Críticos/métodos , Metabolismo Energético/efeitos dos fármacos , Feminino , Humanos , Hipertensão Intracraniana/tratamento farmacológico , Hipertensão Intracraniana/metabolismo , Hipertensão Intracraniana/fisiopatologia , Masculino , Pessoa de Meia-Idade , Acidente Vascular Cerebral/metabolismo , Acidente Vascular Cerebral/fisiopatologia , Resultado do Tratamento
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