The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
Eric L. Zager - One of the best experts on this subject based on the ideXlab platform.
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Physiologic Effects of Xenon in Xenon-CT Cerebral Blood Flow Studies on Comatose Patients
Translational stroke research, 2012Co-Authors: Jennifer A. Kosty, W. A. Kofke, Eileen Maloney-wilensky, Suzanne Frangos, Joshua M. Levine, Peter D. Leroux, Eric L. ZagerAbstract:Despite more than 30 years of clinical use, questions remain about the safety of xenon gas in Xenon-CT cerebral Blood Flow (XeCTCBF) Studies. In particular, xenon’s effect on brain oxygen (PbtO2) in comatose patients is not well defined. Our objective was to assess the effect of a 4.5-min inhalation of 28 % stable xenon on several physiologic variables, including intracranial pressure (ICP), cerebral perfusion pressure (CPP), and PbtO2 in comatose patients (Glasgow Coma Scale [GCS] ≤ 8). Thirty-seven comatose patients who underwent 73 XeCTCBF Studies were identified retrospectively from a prospective observational database. Changes in MAP, HR, SaO2, EtCO2, ICP, CPP, and PbtO2 measured at the start of xenon administration and every minute for 5 min thereafter were assessed. The maximum change in each variable also was determined for each scan to tabulate clinically relevant changes. Statistically, but not clinically significant changes in MAP, HR, and EtCO2 were seen. Xenon had no effect on ICP, and a small, but clinically insignificant decrease in CPP and PbtO2, was observed. There was a varied response to xenon in most measured variables. Clinically significant changes in each were infrequent, and readily reversed with the cessation of the gas. We conclude that xenon does not appear to have a clinically significant effect on ICP, CPP, and PbtO2 and so appears safe to evaluate cerebral Blood Flow in comatose patients.
Haruhide Ito - One of the best experts on this subject based on the ideXlab platform.
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The wash-in/washout protocol in stable xenon CT cerebral Blood Flow Studies.
AJNR. American journal of neuroradiology, 1992Co-Authors: Shiro Kashiwagi, Tetsuo Yamashita, Shigeki Nakano, Willi Prof. Dipl.-phys. Dr. Kalender, Arkadiusz Polacin, Teiichi Takasago, Yuuki Eguchi, Haruhide ItoAbstract:PURPOSE We conducted a comparative study to optimize the scanning and inhalation protocols for xenon CT cerebral Blood Flow (CBF) examination (Xe CT), with the aim of improving the practical performance of Xe CT as a routine clinical examination. MATERIALS AND METHODS Four different inhalation protocols, including 3-min, 6-min, and 8-min wash-in protocols, and a 3-min wash-in/5-min washout protocol, were compared in five healthy volunteers. Each subject underwent two serial Xe CT examinations with an interval of 30 min between the first one (wash-in) and the second one (wash-in/washout). A computer simulation was also performed to support the results of the clinical study. The rate of success was calculated from our experience of 110 clinical cases examined with the wash-in/washout protocol over the last 9 months. RESULTS The mean CBF values with 6-min and 8-min wash-in protocols were 59.0 and 59.5 mL/100-g brain per min in the thalamus, and 19.5 and 19.0 mL/100-g brain per min in the frontal white matter, respectively. The mean CBF values with 3-min wash-in/5-min washout protocol were 60.0 mL/100-g brain per min in the thalamus and 18.5 mL/100-g brain per min in the frontal white matter, respectively. Computer simulation showed improved signal-to-noise ratio by employing the 3-min wash-in/5-min washout protocol instead of 8-min wash-in protocol for the same number of data points. The rate of success improved to 99.1% due to the significant decrease in head motion with the shorter period of inhalation. CONCLUSION A wash-in/washout protocol is a useful alternative in Xe CT CBF measurement and more useful than the wash-in method for clinical purposes.
Jennifer A. Kosty - One of the best experts on this subject based on the ideXlab platform.
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Physiologic Effects of Xenon in Xenon-CT Cerebral Blood Flow Studies on Comatose Patients
Translational stroke research, 2012Co-Authors: Jennifer A. Kosty, W. A. Kofke, Eileen Maloney-wilensky, Suzanne Frangos, Joshua M. Levine, Peter D. Leroux, Eric L. ZagerAbstract:Despite more than 30 years of clinical use, questions remain about the safety of xenon gas in Xenon-CT cerebral Blood Flow (XeCTCBF) Studies. In particular, xenon’s effect on brain oxygen (PbtO2) in comatose patients is not well defined. Our objective was to assess the effect of a 4.5-min inhalation of 28 % stable xenon on several physiologic variables, including intracranial pressure (ICP), cerebral perfusion pressure (CPP), and PbtO2 in comatose patients (Glasgow Coma Scale [GCS] ≤ 8). Thirty-seven comatose patients who underwent 73 XeCTCBF Studies were identified retrospectively from a prospective observational database. Changes in MAP, HR, SaO2, EtCO2, ICP, CPP, and PbtO2 measured at the start of xenon administration and every minute for 5 min thereafter were assessed. The maximum change in each variable also was determined for each scan to tabulate clinically relevant changes. Statistically, but not clinically significant changes in MAP, HR, and EtCO2 were seen. Xenon had no effect on ICP, and a small, but clinically insignificant decrease in CPP and PbtO2, was observed. There was a varied response to xenon in most measured variables. Clinically significant changes in each were infrequent, and readily reversed with the cessation of the gas. We conclude that xenon does not appear to have a clinically significant effect on ICP, CPP, and PbtO2 and so appears safe to evaluate cerebral Blood Flow in comatose patients.
A Jumaoas - One of the best experts on this subject based on the ideXlab platform.
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xenon ct cerebral Blood Flow Studies during continuous depth electrode monitoring in epilepsy patients
American Journal of Neuroradiology, 1993Co-Authors: David W. Johnson, Richard M. Dasheiff, J P Hogg, S Pentheny, Howard Yonas, A JumaoasAbstract:PURPOSE: To observe and describe cerebral Blood Flow (CBF) alterations immediately following depth electrode stimulation of the temporal lobe in patients with medically intractable epilepsy. MATERIALS AND METHODS: Five patients with partial epilepsy undergoing presurgical evaluation were chosen for xenon/CT cerebral Blood Flow (Xe/CT CBF) measurement immediately following electrically stimulated seizures via stereotactically placed temporal lobe depth electrodes. Each patient had a baseline Xe/CT CBF study. Four of the five patients had a total of seven temporal lobe stimulations each followed by a Xe/CT CBF study. The other patient had right temporal lobe electrical status epilepticus and was scanned without stimulation or electroencephalogram monitoring. RESULTS: Of the four baseline or interictal scans, no areas of abnormally low Flow were detected, but one baseline scan had elevated Flows of 115 mL.100 g-1.min-1 in the left temporal lobe. One stimulation elicited 8 seconds of afterdischarge potentials, but no alteration of CBF was detected. One stimulation elicited an aura but no electrographic seizure was detected. This resulted, however, in bitemporal lobe elevation of CBF. The other five temporal lobe stimulations resulted in 17-63 seconds of afterdischarge potentials and all resulted in elevation of CBF to 69-118 mL.100 g-1.min-1. One of these five stimulations resulted in seizure and localized elevation of CBF. Following seizure activity, elevated CBF began to return to baseline levels by 20 minutes. CONCLUSION: This study reveals a direct spatial and temporal relationship of elevated CBF with seizures. This study provides the most direct data to date in human subjects that focal seizure activity elevates CBF. Since seizures are known to increase metabolic activity in the activated tissue, this data also supports the assumption of coupling between CBF and metabolism during the pathologic process of a seizure.
Howard Yonas - One of the best experts on this subject based on the ideXlab platform.
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The Use of Xenon/CT Cerebral Blood Flow Studies in Acute Stroke
Cerebral Blood Flow, 2003Co-Authors: Howard YonasAbstract:Whether ischemic stroke is due to an embolus from the heart or to closure of a perforating vessel due to chronic hypertension, the final common pathway is a compromise of Blood Flow. While there is a complex system of hemodynamic mechanisms intended to protect neuronal tissue from less severe reductions of cerebral Blood Flow (CBF), it is the location, duration and severity of the compromise of CBF that determines the onset of a neurological deficit as well as the transition from reversible to irreversible ischemia [1]. While technologies that examine other physiological variables are all interesting and potentially useful, during the initial hours after an ischemic event the pathophysiology is Flow driven with other variables being secondary events. Thus, it should follow that rapidly accessible, quantitative, high resolution CBF information should play a central role in the diagnosis and management of acute ischemic stroke.
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xenon ct cerebral Blood Flow Studies during continuous depth electrode monitoring in epilepsy patients
American Journal of Neuroradiology, 1993Co-Authors: David W. Johnson, Richard M. Dasheiff, J P Hogg, S Pentheny, Howard Yonas, A JumaoasAbstract:PURPOSE: To observe and describe cerebral Blood Flow (CBF) alterations immediately following depth electrode stimulation of the temporal lobe in patients with medically intractable epilepsy. MATERIALS AND METHODS: Five patients with partial epilepsy undergoing presurgical evaluation were chosen for xenon/CT cerebral Blood Flow (Xe/CT CBF) measurement immediately following electrically stimulated seizures via stereotactically placed temporal lobe depth electrodes. Each patient had a baseline Xe/CT CBF study. Four of the five patients had a total of seven temporal lobe stimulations each followed by a Xe/CT CBF study. The other patient had right temporal lobe electrical status epilepticus and was scanned without stimulation or electroencephalogram monitoring. RESULTS: Of the four baseline or interictal scans, no areas of abnormally low Flow were detected, but one baseline scan had elevated Flows of 115 mL.100 g-1.min-1 in the left temporal lobe. One stimulation elicited 8 seconds of afterdischarge potentials, but no alteration of CBF was detected. One stimulation elicited an aura but no electrographic seizure was detected. This resulted, however, in bitemporal lobe elevation of CBF. The other five temporal lobe stimulations resulted in 17-63 seconds of afterdischarge potentials and all resulted in elevation of CBF to 69-118 mL.100 g-1.min-1. One of these five stimulations resulted in seizure and localized elevation of CBF. Following seizure activity, elevated CBF began to return to baseline levels by 20 minutes. CONCLUSION: This study reveals a direct spatial and temporal relationship of elevated CBF with seizures. This study provides the most direct data to date in human subjects that focal seizure activity elevates CBF. Since seizures are known to increase metabolic activity in the activated tissue, this data also supports the assumption of coupling between CBF and metabolism during the pathologic process of a seizure.