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Biomedical subjects

E Deibert

Publications and source records attributed to E Deibert.

8 recordsLinked to original sources

Safety of hemodynamic augmentation in patients treated with Guglielmi detachable coils after acute aneurysmal subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Guglielmi detachable coils (GDC) used in the treatment of intracranial aneurysms do not always completely occlude the aneurysm. Thus, after an acute subarachnoid hemorrhage (SAH), there is a theoretical risk of rebleeding from coiled aneurysms, especially when blood pressure is elevated. The aim of this study is to determine whether use of hemodynamic augmentation (HA) to treat delayed ischemic deficits (DID) will increase the risk of rebleeding in these patients. METHODS: Delayed ischemic deficits developed in 12 (7 women and 5 men, aged 31 to 64 years) of 51 patients treated with GDC for acute SAH over a 4-year period. Aneurysms in all 12 patients were >/=80% obliterated with GDC, and there was >/=90% obliteration of 78% of the aneurysms. Hemodynamic augmentation with fluids, phenylephrine, dopamine, and/or dobutamine was used to treat DID for a mean duration of 3 days (range 1 to 11 days). RESULTS: With HA, mean arterial blood pressure (MAP) rose 15% (range 0 to 30%) and systolic blood pressure (SBP) rose 13% (range 0 to 29%) above baseline. MAP was maintained at >10% above baseline for 65% of the treatment period. The maximum MAP was 104 to 170 mm Hg (mean 140 mm Hg), and maximum SBP was 154 to 261 mm Hg (mean 210 mm Hg). No patient had rebleeding or any significant complication during the course of therapy. CONCLUSIONS: Based on this limited series of patients, we believe that it may be safe to use HA in patients treated with GDC for SAH.

Acute Disease↗

Hemodynamic monitoring in the neurological intensive care unit.

The neurointensivist needs to have a thorough understanding of hemodynamic issues and the interaction of the brain and the cardiovascular system. Before one decides to intervene and try to correct an apparent "abnormal hemodynamic parameter" one needs to think whether such an intervention is indeed warranted and what effect the intervention would have on the cerebral circulation. The neurointensivist thus needs to approach these issues differently from the approach an internist or general intensivist would take.

Blood Pressure↗

Reversible left ventricular dysfunction associated with raised troponin I after subarachnoid haemorrhage does not preclude successful heart transplantation.

Transient abnormalities in ECGs, echocardiograms, and cardiac enzymes have been described in the acute setting of subarachnoid haemorrhage. In addition, left ventricular dysfunction has been reported at the time of brain death. A patient with an acute subarachnoid haemorrhage who presented with raised troponin I (TnI) concentrations and diffuse left ventricular dysfunction is described. After declaration of brain death 32 hours later, the heart was felt initially not suitable for transplantation. A normal cardiac catheterisation, however, lead to successful transplantation of the donor heart. Raised catecholamine concentrations and metabolic perturbations have been proposed as the mechanisms leading to the cardiac dysfunction seen with brain death. This may be a biphasic process, allowing time for myocardial recovery and reversal of the left ventricular dysfunction. Awareness of this phenomenon in the acutely ill neurologic population needs to be raised in order to prevent the unnecessary rejection of donor hearts.

Biomarkers↗

No reduction in cerebral metabolism as a result of early moderate hyperventilation following severe traumatic brain injury.

OBJECT: Hyperventilation has been used for many years in the management of patients with traumatic brain injury (TBI). Concern has been raised that hyperventilation could lead to cerebral ischemia; these concerns have been magnified by reports of reduced cerebral blood flow (CBF) early after severe TBI. The authors tested the hypothesis that moderate hyperventilation induced early after TBI would not produce a reduction in CBF severe enough to cause cerebral energy failure (CBF that is insufficient to meet metabolic needs). METHODS: Nine patients were studied a mean of 11.2+/-1.6 hours (range 8-14 hours) after TBI occurred. The patients' mean Glasgow Coma Scale score was 5.6+/-1.8 and their mean age 27+/-9 years; eight of the patients were male. Intracranial pressure (ICP), mean arterial blood pressure, and jugular venous oxygen content were monitored and cerebral perfusion pressure was maintained at a level higher than 70 mm Hg by using vasopressors when needed. Measurements of CBF, cerebral blood volume (CBV), cerebral metabolic rate for oxygen (CMRO2), oxygen extraction fraction (OEF), and cerebral venous oxygen content (CvO2) were made before and after 30 minutes of hyperventilation to a PaCO2 of 30+/-2 mm Hg. Ten age-matched healthy volunteers were used as normocapnic controls. Global CBF, CBV, and CvO2 did not differ between the two groups, but in the TBI patients CMRO2 and OEF were reduced (1.59+/-0.44 ml/100 g/minute [p < 0.01] and 0.31+/-0.06 [p < 0.0001], respectively). During hyperventilation, global CBF decreased to 25.5+/-8.7 ml/100 g/minute (p < 0.0009), CBV fell to 2.8+/-0.56 ml/100 g (p < 0.001), OEF rose to 0.45+/-0.13 (p < 0.02), and CvO2 fell to 8.3+/-3 vol% (p < 0.02); CMRO2 remained unchanged. CONCLUSIONS: The authors conclude that early, brief, moderate hyperventilation does not impair global cerebral metabolism in patients with severe TBI and, thus, is unlikely to cause further neurological injury. Additional studies are needed to assess focal changes, the effects of more severe hyperventilation, and the effects of hyperventilation in the setting of increased ICP.

Adult↗

Neural pathways in tactile object recognition.

OBJECTIVE: To define further the brain regions involved in tactile object recognition using functional MRI (fMRI) techniques. BACKGROUND: The neural substrates involved in tactile object recognition (TOR) have not been elucidated. Studies of nonhuman primates and humans suggest that basic motor and somatosensory mechanisms are involved at a peripheral level; however, the mechanisms of higher order object recognition have not been determined. METHODS: The authors investigated 11 normal volunteers utilizing fMRI techniques in an attempt to determine the neural pathways involved in TOR. Each individual performed a behavioral paradigm with the activated condition involving identification of objects by touch, with identification of rough/smooth as the control. RESULTS: Data suggest that in a majority of individuals, TOR involves the calcarine and extrastriatal cortex, inferior parietal lobule, inferior frontal gyrus, and superior frontal gyrus-polar region. CONCLUSIONS: TOR may utilize visual systems to access an internal object representation. The parietal cortices and inferior frontal regions may be involved in a concomitant lexical strategy of naming the object being examined. Frontal polar activation likely serves a role in visuospatial working memory or in recognizing unusual representations of objects. Overall, these findings suggest that TOR could involve a network of cortical regions subserving somatosensory, motor, visual, and, at times, lexical processing. The primary finding suggests that in this normal study population, the visual cortices may be involved in the topographic spatial processing of TOR.

Adult↗

Mechanical ventilation for ischemic stroke and intracerebral hemorrhage: indications, timing, and outcome.

OBJECTIVE: To compare the incidence, indication, and timing of intubation and outcome in patients with cerebral infarction (ISCH) and intracerebral hemorrhage (HEM) requiring mechanical ventilation (MV). BACKGROUND: Poor outcomes have been reported for ISCH patients requiring MV. Because the target population, pathophysiology, and management of ISCH and HEM patients differ considerably, we compared the characteristics of patients with ISCH and HEM who required MV. METHODS: A retrospective review of ISCH and HEM stroke patients who underwent MV at a tertiary care academic center from 1994 to 1997 was performed to determine age, sex, type, and location of stroke (anterior or posterior circulation); brainstem dysfunction at intubation (pupillary, corneal, and oculocephalic reflexes); indication for intubation (neurologic deterioration, cardiopulmonary deterioration, or elective intubation for surgery); timing of intubation (on presentation or later); comorbidities; and outcome (hospital disposition). RESULTS: A total of 230 patients, 74 with ISCH and 156 with HEM (mean age, 61 +/- 16 years; male-to-female ratio, 1.15:1), underwent MV. Intubation rates were 6% for ISCH patients and 30% for HEM patients. Two-thirds of the patients required intubation on presentation (84% were intubated for neurologic deterioration) and 131 patients (57%) died (ISCH, 55%; HEM, 58%). Signs of brainstem dysfunction predicted a higher mortality for both groups. Additionally, early intubation and older age predicted mortality for HEM, and male gender predicted mortality in ISCH. Stroke location and comorbidities did not influence outcome. CONCLUSIONS: MV in acute stroke is associated with high mortality. Mortality and outcome were similar for ISCH and HEM; however, the factors predictive of outcome may differ and influence decisions about the use of MV in such patients.

Adult↗

A case of CNS cryptococcosis presenting with slowly alternating skew deviation.

Alternating skew deviation is a rare malfunction of vertical ocular motility, which has previously been described with lesions of the brainstem and cerebellum, although the precise localization is unknown. We describe an HIV seronegative patient with CNS cryptococcosis, whose initial presentation included slowly alternating skew deviation.

Adult↗