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Sayin ES, Duffin J, Poublanc J, Venkatraghavan L, Mikulis DJ, Fisher JA, Sobczyk O. Determining the effects of elevated partial pressure of oxygen on hypercapnia-induced cerebrovascular reactivity. J Cereb Blood Flow Metab 2023; 43:2085-2095. [PMID: 37632334 PMCID: PMC10925865 DOI: 10.1177/0271678x231197000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 07/17/2023] [Accepted: 07/19/2023] [Indexed: 08/28/2023]
Abstract
Evaluation of cerebrovascular reactivity (CVR) to hypo- and hypercapnia is a valuable test for the assessment of vasodilatory reserve. While hypercapnia-induced CVR testing is usually performed at normoxia, mild hyperoxia may increase tolerability of hypercapnia by reducing the ventilatory distress. However, the effects of mild hyperoxia on CVR was unknown. We therefore recruited 21 patients with a range of steno-occlusive diseases and 12 healthy participants who underwent a standardized 13-minute step plus ramp CVR test with a carbon dioxide gas challenge at the subject's resting end-tidal partial pressure of oxygen or at mild hyperoxia (PetO2 = 150 mmHg) depending on to which group they were assigned. In 11 patients, the second CVR test was at normoxia to examine test-retest differences. CVR was defined as % Δ Signal/ΔPetCO2. We found that there was no significant difference between CVR test results conducted at normoxia and at mild hyperoxia for participants in Groups 1 and 2 for the step and ramp portion. We also found no difference between test and retest CVR at normoxia for patients with cerebrovascular pathology (Group 3) for step and ramp portion. We concluded normoxic CVR is repeatable, and that mild hyperoxia does not affect CVR.
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Affiliation(s)
- Ece Su Sayin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - James Duffin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Julien Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Lashmikumar Venkatraghavan
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - David John Mikulis
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
| | - Joseph Arnold Fisher
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
| | - Olivia Sobczyk
- Department of Anaesthesia and Pain Management, University Health Network, University of Toronto, Toronto, ON, Canada
- Joint Department of Medical Imaging and the Functional Neuroimaging Lab, University Health Network, Toronto, ON, Canada
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Dinsmore M, Venkatraghavan L. Clinical applications of point‐of‐care ultrasound in brain injury: a narrative review. Anaesthesia 2022; 77 Suppl 1:69-77. [DOI: 10.1111/anae.15604] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/01/2021] [Indexed: 12/24/2022]
Affiliation(s)
- M. Dinsmore
- Department of Anaesthesia and Pain Management Toronto Western Hospital University Health Network University of Toronto Toronto ON Canada
| | - L. Venkatraghavan
- Department of Anaesthesia and Pain Management Toronto Western Hospital University Health Network University of Toronto Toronto ON Canada
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McKetton L, Venkatraghavan L, Rosen C, Mandell DM, Sam K, Sobczyk O, Poublanc J, Gray E, Crawley A, Duffin J, Fisher JA, Mikulis DJ. Improved White Matter Cerebrovascular Reactivity after Revascularization in Patients with Steno-Occlusive Disease. AJNR Am J Neuroradiol 2018; 40:45-50. [PMID: 30573457 DOI: 10.3174/ajnr.a5912] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 10/08/2018] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE One feature that patients with steno-occlusive cerebrovascular disease have in common is the presence of white matter (WM) lesions on MRI. The purpose of this study was to evaluate the effect of direct surgical revascularization on impaired WM cerebrovascular reactivity in patients with steno-occlusive disease. MATERIALS AND METHODS We recruited 35 patients with steno-occlusive disease, Moyamoya disease (n = 24), Moyamoya syndrome (n = 3), atherosclerosis (n = 6), vasculitis (n = 1), and idiopathic stenosis (n = 1), who underwent unilateral brain revascularization using a direct superficial temporal artery-to-MCA bypass (19 women; mean age, 45.8 ± 16.5 years). WM cerebrovascular reactivity was measured preoperatively and postoperatively using blood oxygen level-dependent (BOLD) MR imaging during iso-oxic hypercapnic changes in end-tidal carbon dioxide and was expressed as %Δ BOLD MR signal intensity per millimeter end-tidal partial pressure of CO2. RESULTS WM cerebrovascular reactivity significantly improved after direct unilateral superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass in the revascularized hemisphere in the MCA territory (mean ± SD, -0.0005 ± 0.053 to 0.053 ± 0.046 %BOLD/mm Hg; P < .0001) and in the anterior cerebral artery territory (mean, 0.0015 ± 0.059 to 0.021 ± 0.052 %BOLD/mm Hg; P = .005). There was no difference in WM cerebrovascular reactivity in the ipsilateral posterior cerebral artery territory nor in the vascular territories of the nonrevascularized hemisphere (P < .05). CONCLUSIONS Cerebral revascularization surgery is an effective treatment for reversing preoperative cerebrovascular reactivity deficits in WM. In addition, direct-STA-MCA bypass may prevent recurrence of preoperative symptoms.
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Affiliation(s)
- L McKetton
- From the Division of Neuroradiology, Joint Department of Medical Imaging (L.M., C.R., D.M.M., K.S., O.S., J.P., E.G., A.C., D.J.M.)
| | - L Venkatraghavan
- Department of Anesthesia and Pain Management (L.V., J.A.F.), University Health Network, Toronto, Ontario, Canada
| | - C Rosen
- From the Division of Neuroradiology, Joint Department of Medical Imaging (L.M., C.R., D.M.M., K.S., O.S., J.P., E.G., A.C., D.J.M.)
| | - D M Mandell
- From the Division of Neuroradiology, Joint Department of Medical Imaging (L.M., C.R., D.M.M., K.S., O.S., J.P., E.G., A.C., D.J.M.)
| | - K Sam
- From the Division of Neuroradiology, Joint Department of Medical Imaging (L.M., C.R., D.M.M., K.S., O.S., J.P., E.G., A.C., D.J.M.).,Russell H. Morgan Department of Radiology and Radiological Science (K.S.), John Hopkins School of Medicine, Baltimore, Maryland
| | - O Sobczyk
- From the Division of Neuroradiology, Joint Department of Medical Imaging (L.M., C.R., D.M.M., K.S., O.S., J.P., E.G., A.C., D.J.M.)
| | - J Poublanc
- From the Division of Neuroradiology, Joint Department of Medical Imaging (L.M., C.R., D.M.M., K.S., O.S., J.P., E.G., A.C., D.J.M.)
| | - E Gray
- From the Division of Neuroradiology, Joint Department of Medical Imaging (L.M., C.R., D.M.M., K.S., O.S., J.P., E.G., A.C., D.J.M.)
| | - A Crawley
- From the Division of Neuroradiology, Joint Department of Medical Imaging (L.M., C.R., D.M.M., K.S., O.S., J.P., E.G., A.C., D.J.M.)
| | - J Duffin
- Department of Physiology (J.D., J.A.F.).,Institute of Medical Sciences (J.D., J.A.F., D.J.M.), University of Toronto, Toronto, Ontario, Canada
| | - J A Fisher
- Department of Anesthesia and Pain Management (L.V., J.A.F.), University Health Network, Toronto, Ontario, Canada.,Department of Physiology (J.D., J.A.F.).,Institute of Medical Sciences (J.D., J.A.F., D.J.M.), University of Toronto, Toronto, Ontario, Canada
| | - D J Mikulis
- From the Division of Neuroradiology, Joint Department of Medical Imaging (L.M., C.R., D.M.M., K.S., O.S., J.P., E.G., A.C., D.J.M.) .,Institute of Medical Sciences (J.D., J.A.F., D.J.M.), University of Toronto, Toronto, Ontario, Canada
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Venkatraghavan L, Li L, Bailey T, Manninen PH, Tymianski M. Sumatriptan improves postoperative quality of recovery and reduces postcraniotomy headache after cranial nerve decompression. Br J Anaesth 2018; 117:73-9. [PMID: 27317706 DOI: 10.1093/bja/aew152] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/10/2016] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Microvascular decompression (MVD) is a surgical treatment for cranial nerve disorders via a small craniotomy. The postoperative pain of this procedure can be classified as surgical site somatic pain and postcraniotomy headache similar in nature to a migraine, including its association with photophobia, nausea, and vomiting. This headache can be difficult to treat and can impact on postoperative recovery. Sumatriptan is used to treat migraine-like headaches in various settings. This single-centre randomized controlled trial investigated whether postoperative administration of sumatriptan after MVD surgery impacts the quality of postoperative recovery. METHODS Fifty patients who complained of postoperative headache after MVD were randomized to receive an s.c. injection of sumatriptan (6 mg) or saline. The primary outcome was quality of recovery as measured by the Quality of Recovery-40 (QoR-40) score at 24 h. RESULTS The QoR-40 scores were significantly higher in the sumatriptan group (median 184; interquartile range 169-196) than in the placebo group (133; 119-155; P<0.01), suggesting higher quality of recovery. The sumatriptan group also had significantly lower headache scores at 4, 12, and 24 h. There were no significant differences in other secondary outcomes. CONCLUSIONS Use of sumatriptan improved the quality of recovery as measured by the QoR-40 and reduction of headache at 24 h after surgery. Sumatriptan is a useful alternative treatment for postcraniotomy headache. The mechanism remains unknown but could be related to reduction in headache, mood modulation, or both, mediated by a serotonin effect. CLINICAL TRIAL REGISTRATION NCT01632657.
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Affiliation(s)
| | - L Li
- Department of Anesthesia Present address: Department of Anaesthesia, Ninewells Hospital and Medical School, Dundee, UK
| | - T Bailey
- Department of Anesthesia Present address: Department of Anaesthesia, Waikato Hospital, Hamilton 3204, New Zealand
| | | | - M Tymianski
- Department of Surgery, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
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Dinsmore M, Han JS, Fisher JA, Chan VWS, Venkatraghavan L. Effects of acute controlled changes in end-tidal carbon dioxide on the diameter of the optic nerve sheath: a transorbital ultrasonographic study in healthy volunteers. Anaesthesia 2017; 72:618-623. [PMID: 28177116 DOI: 10.1111/anae.13784] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2016] [Indexed: 02/03/2023]
Abstract
Transorbital ultrasonographic measurement of the diameter of the optic nerve sheath is a non-invasive, bed-side examination for detecting raised intracranial pressure. However, the ability of the optic nerve sheath diameter to predict acute changes in intracranial pressures remains unknown. The aim of this study was to examine the dynamic changes of the optic nerve sheath diameter in response to mild fluctuations in cerebral blood volume induced by changes in end-tidal carbon dioxide. We studied 11 healthy volunteers. End-tidal carbon dioxide was controlled by a model-based prospective end-tidal targeting system (RespirAct™). The volunteers' end-tidal carbon dioxide was targeted and maintained for 10 min each at normocapnia (baseline); hypercapnia (6.5 kPa); normocapnia (baseline 1); hypocapnia (3.9 kPa) and on return to normocapnia (baseline 2). A single investigator repeatedly measured the optic nerve sheath diameter for 10 min at each level of carbon dioxide. With hypercapnia, there was a significant increase in optic nerve sheath diameter, with a mean (SD) increase from baseline 4.2 (0.7) mm to 4.8 (0.8) mm; p < 0.001. On return to normocapnia, the optic nerve sheath diameter rapidly reverted back to baseline values. This study confirms dynamic changes in the optic nerve sheath diameter with corresponding changes in carbon dioxide, and their reversibly with normocapnia.
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Affiliation(s)
- M Dinsmore
- Department of Anaesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - J S Han
- Department of Anaesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - J A Fisher
- Department of Anaesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - V W S Chan
- Department of Anaesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - L Venkatraghavan
- Department of Anaesthesia, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
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Sam K, Crawley AP, Poublanc J, Conklin J, Sobczyk O, Mandell DM, Duffin J, Venkatraghavan L, Fisher JA, Black SE, Mikulis DJ. Vascular Dysfunction in Leukoaraiosis. AJNR Am J Neuroradiol 2016; 37:2258-2264. [PMID: 27492072 DOI: 10.3174/ajnr.a4888] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 06/07/2016] [Indexed: 01/04/2023]
Abstract
BACKGROUND AND PURPOSE The pathogenesis of leukoaraiosis has long been debated. This work addresses a less well-studied mechanism, cerebrovascular reactivity, which could play a leading role in the pathogenesis of this disease. Our aim was to evaluate blood flow dysregulation and its relation to leukoaraiosis. MATERIALS AND METHODS Cerebrovascular reactivity, the change in the blood oxygen level-dependent 3T MR imaging signal in response to a consistently applied step change in the arterial partial pressure of carbon dioxide, was measured in white matter hyperintensities and their contralateral spatially homologous normal-appearing white matter in 75 older subjects (age range, 50-91 years; 40 men) with leukoaraiosis. Additional quantitative evaluation of regions of leukoaraiosis was performed by using diffusion (n = 75), quantitative T2 (n = 54), and DSC perfusion MRI metrics (n = 25). RESULTS When we compared white matter hyperintensities with contralateral normal-appearing white matter, cerebrovascular reactivity was lower by a mean of 61.2% ± 22.6%, fractional anisotropy was lower by 44.9 % ± 6.9%, and CBF was lower by 10.9% ± 11.9%. T2 was higher by 61.7% ± 13.5%, mean diffusivity was higher by 59.0% ± 11.7%, time-to-maximum was higher by 44.4% ± 30.4%, and TTP was higher by 6.8% ± 5.8% (all P < .01). Cerebral blood volume was lower in white matter hyperintensities compared with contralateral normal-appearing white matter by 10.2% ± 15.0% (P = .03). CONCLUSIONS Not only were resting blood flow metrics abnormal in leukoaraiosis but there is also evidence of reduced cerebrovascular reactivity in these areas. Studies have shown that reduced cerebrovascular reactivity is more sensitive than resting blood flow parameters for assessing vascular insufficiency. Future work is needed to examine the sensitivity of resting-versus-dynamic blood flow measures for investigating the pathogenesis of leukoaraiosis.
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Affiliation(s)
- K Sam
- From the Departments of Physiology (K.S., J.D., J.A.F.).,Division of Neuroradiology (K.S., A.P.C., J.P., J.C., O.S., D.M.M., D.J.M.), Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | - A P Crawley
- Medical Imaging (A.P.C., D.J.M.), University of Toronto, Toronto, Ontario, Canada.,Division of Neuroradiology (K.S., A.P.C., J.P., J.C., O.S., D.M.M., D.J.M.), Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | - J Poublanc
- Division of Neuroradiology (K.S., A.P.C., J.P., J.C., O.S., D.M.M., D.J.M.), Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | - J Conklin
- Division of Neuroradiology (K.S., A.P.C., J.P., J.C., O.S., D.M.M., D.J.M.), Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | - O Sobczyk
- Division of Neuroradiology (K.S., A.P.C., J.P., J.C., O.S., D.M.M., D.J.M.), Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | - D M Mandell
- Division of Neuroradiology (K.S., A.P.C., J.P., J.C., O.S., D.M.M., D.J.M.), Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | - J Duffin
- From the Departments of Physiology (K.S., J.D., J.A.F.).,Department of Anesthesiology (J.D., L.V., J.A.F.), University Health Network and The University of Toronto, Toronto, Ontario, Canada
| | - L Venkatraghavan
- Department of Anesthesiology (J.D., L.V., J.A.F.), University Health Network and The University of Toronto, Toronto, Ontario, Canada
| | - J A Fisher
- From the Departments of Physiology (K.S., J.D., J.A.F.).,Department of Anesthesiology (J.D., L.V., J.A.F.), University Health Network and The University of Toronto, Toronto, Ontario, Canada
| | - S E Black
- L.C. Campbell Cognitive Neurology Research Unit (S.E.B.), Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - D J Mikulis
- Medical Imaging (A.P.C., D.J.M.), University of Toronto, Toronto, Ontario, Canada .,Division of Neuroradiology (K.S., A.P.C., J.P., J.C., O.S., D.M.M., D.J.M.), Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
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Goettel N, Bharadwaj S, Venkatraghavan L, Mehta J, Bernstein M, Manninen P. Dexmedetomidine vs propofol-remifentanil conscious sedation for awake craniotomy: a prospective randomized controlled trial † †Euroanaesthesia Congress, May 31, 2015, Berlin, Germany, and Canadian Anesthesiologists’ Society Annual Meeting, June 20, 2015, Ottawa, Canada. ‡ ‡This Article is accompanied by Editorial Aew113. Br J Anaesth 2016; 116:811-21. [DOI: 10.1093/bja/aew024] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2016] [Indexed: 12/23/2022] Open
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Yeoh TY, Tan A, Manninen P, Chan VWS, Venkatraghavan L. Effect of different surgical positions on the cerebral venous drainage: a pilot study using healthy volunteers. Anaesthesia 2016; 71:806-13. [DOI: 10.1111/anae.13494] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2016] [Indexed: 11/30/2022]
Affiliation(s)
- T. Y. Yeoh
- Department of Anaesthesia; Toronto Western Hospital; University of Toronto; Toronto Ontario Canada
| | - A. Tan
- Department of Anaesthesia; Toronto Western Hospital; University of Toronto; Toronto Ontario Canada
| | - P. Manninen
- Department of Anaesthesia; Toronto Western Hospital; University of Toronto; Toronto Ontario Canada
| | - V. W. S. Chan
- Department of Anaesthesia; Toronto Western Hospital; University of Toronto; Toronto Ontario Canada
| | - L. Venkatraghavan
- Department of Anaesthesia; Toronto Western Hospital; University of Toronto; Toronto Ontario Canada
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Poublanc J, Crawley AP, Sobczyk O, Montandon G, Sam K, Mandell DM, Dufort P, Venkatraghavan L, Duffin J, Mikulis DJ, Fisher JA. Measuring cerebrovascular reactivity: the dynamic response to a step hypercapnic stimulus. J Cereb Blood Flow Metab 2015; 35:1746-56. [PMID: 26126862 PMCID: PMC4635229 DOI: 10.1038/jcbfm.2015.114] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Revised: 04/13/2015] [Accepted: 04/14/2015] [Indexed: 11/09/2022]
Abstract
We define cerebral vascular reactivity (CVR) as the ratio of the change in blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) signal (S) to an increase in blood partial pressure of CO2 (PCO2): % Δ S/Δ PCO2 mm Hg. Our aim was to further characterize CVR into dynamic and static components and then study 46 healthy subjects collated into a reference atlas and 20 patients with unilateral carotid artery stenosis. We applied an abrupt boxcar change in PCO2 and monitored S. We convolved the PCO2 with a set of first-order exponential functions whose time constant τ was increased in 2-second intervals between 2 and 100 seconds. The τ corresponding to the best fit between S and the convolved PCO2 was used to score the speed of response. Additionally, the slope of the regression between S and the convolved PCO2 represents the steady-state CVR (ssCVR). We found that both prolongations of τ and reductions in ssCVR (compared with the reference atlas) were associated with the reductions in CVR on the side of the lesion. τ and ssCVR are respectively the dynamic and static components of measured CVR.
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Affiliation(s)
- Julien Poublanc
- Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | - Adrian P Crawley
- Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | - Olivia Sobczyk
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Gaspard Montandon
- Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | - Kevin Sam
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Daniel M Mandell
- Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | - Paul Dufort
- Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada
| | | | - James Duffin
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Department of Anaesthesia and Pain Management, University Health Network, Toronto, Ontario, Canada
| | - David J Mikulis
- Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Joseph A Fisher
- Joint Department of Medical Imaging, University Health Network, Toronto, Ontario, Canada.,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Department of Anaesthesia and Pain Management, University Health Network, Toronto, Ontario, Canada
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Venkatraghavan L. Author Reply. Journal of Neuroanaesthesiology and Critical Care 2015. [DOI: 10.4103/2348-0548.155470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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11
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Tedder A, Rakhman E, Manninen P, Venkatraghavan L. Profound hypertension with dexmedetomidine during insertion of deep brain stimulator. Journal of Neuroanaesthesiology and Critical Care 2015. [DOI: 10.4103/2348-0548.148393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
AbstractDexmedetomidine is now frequently used in the anaesthetic management of patients undergoing deep brain stimulator insertion for movement disorders. We present two patients with Parkinson’s disease and dystonia who developed marked increase in blood pressure and level of sedation during the infusion of a loading dose of dexmedetomidine (1 mcg/kg over 10 min). Both patients required treatment of their blood pressure. The first patient also had a computed tomography of the brain to rule out an intracranial event. The patients recovered from these untoward events in approximately 30 min. The possible explanations for both the hypertension and oversedation were underestimation of the severity of the patients’ underlying disease process and a relative overdose of the loading dose of dexmedetomidine.
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Affiliation(s)
- Allison Tedder
- Department of Anesthesia, University of Toronto, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Evgeny Rakhman
- Department of Anesthesia, University of Toronto, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Pirjo Manninen
- Department of Anesthesia, University of Toronto, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Lashmikumar Venkatraghavan
- Department of Anesthesia, University of Toronto, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
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Venkatraghavan L, Tymianski S, Singh J. Do transfusion requirements increase after the diagnosis of vasospasm in patients with aneurysmal subarachnoid haemorrhage? Journal of Neuroanaesthesiology and Critical Care 2015. [DOI: 10.4103/2348-0548.148387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Abstract
Background: Many patients experience impaired cerebral oxygen delivery secondary to vasospasm and delayed cerebral ischemia following aneurysmal subarachnoid haemorrhage (SAH). Anaemia is common after SAH affecting up to 50% patients, which may decrease cerebral oxygen delivery and is associated with worse clinical outcomes. Transfusion of allogeneic red cells increases the oxygen content of the blood but it not consistently associated with improved physiologic markers of clinical outcomes. The threshold for transfusion is not clear in patients with SAH. A recent survey found that most physicians would alter their transfusion threshold in SAH patients who develop delayed ischemia. The objective of our study is to identify the predictors of transfusion and to determine if the diagnosis of delayed ischemia increases the transfusion rates in patients with aneurysmal subarachnoid haemorrhage. Materials and Methods: We retrospectively reviewed the charts of 100 consecutive patients with SAH who were admitted to ICU for mechanical ventilation, and collected demographic and clinical data. Data were analyzed for the association between clinical factors and transfusion the differences in transfusion between the patients with and without vasospasm. Statistical methods included the t-test, univariate analysis and multivariate analysis. Results: Data from 96 patients were included in the analysis. Incidence of anaemia haemoglobin (Hb) < 100 gm/l and vasospasm were 67% (64/96) and 39% (38/96) respectively. Of 64 patients with anaemia, 27 patients received transfusion, while 38 patients did not receive a transfusion. The transfusion rates were similar between those who had vasospasm and who did not. However, out of the 14 patients with vasospasm who received a transfusion, 11 patients had been transfused after experiencing vasospasm, while only 3 were transfused before. On multivariate analysis only female sex, starting Hb levels and lowest Hb levels were found to be predictors of transfusion. Presence or absence of vasospasm was not found to be a predictor. Conclusions: From our retrospective review, we conclude that the incidence of anaemia is higher in patients with vasospasm. Sex and starting and lowest Hb levels were the only predictors of transfusion likelihood in aneurysmal subarachnoid haemorrhage while presence of vasospasm was not.
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Affiliation(s)
- Lashmikumar Venkatraghavan
- Departments of Anesthesia and Critical Care, University of Toronto, Toronto Western Hospital, University Health Network, Ontario, Canada
| | - Sarah Tymianski
- Departments of Anesthesia and Critical Care, University of Toronto, Toronto Western Hospital, University Health Network, Ontario, Canada
| | - Jeffrey Singh
- Departments of Anesthesia and Critical Care, University of Toronto, Toronto Western Hospital, University Health Network, Ontario, Canada
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Sharma R, Manninen P, Venkatraghavan L. Monitoring the depth of anaesthesia using the new modified entropy sensors during supratentorial craniotomy: Our experience. Journal of Neuroanaesthesiology and Critical Care 2015. [DOI: 10.4103/2348-0548.148384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Abstract
Background: Monitoring the depth of anaesthesia can be a challenge in patients undergoing supratentorial craniotomy because the conventional sensors for both bispectral index and entropy monitors lose their contact with a brain after scalp elevation. The new sensors for the entropy monitor are more flexible and can be placed in different locations. The purpose of this study was to determine the feasibility on the use of new GE entropy sensors in monitoring depth of anaesthesia in patients undergoing supratentorial craniotomy. Materials and Methods: We retrospectively reviewed the data from 20 consecutive patients undergoing supratentorial craniotomy who had the monitoring of the depth of anaesthesia using modified entropy sensors. Prior to the induction of anaesthesia, the new GE entropy sensor (P/N M1038681) was applied in a modified fashion. We measured the state entropy (SE) and response entropy (RE) at 12 perioperative time points. Entropy values were compared with the clinical indices of depth of anaesthesia. Results: Data from 20 consecutive patients (orbitozygomatic craniotomy [10] and bifrontal craniotomy [10]) were analysed. Monitoring was possible in all the patients. The changes in entropy values correlated with clinical indices of depth of anaesthesia. However, some patients showed variations in absolute values (RE and SE) during the intraoperative period without any changes in the level of anaesthetic depth. Conclusions: Monitoring the depth of anaesthesia is feasible with the use of new entropy sensors in patients undergoing supratentorial craniotomy. In contrast to standard sensors, the new sensors offer flexibility with the placement.
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Affiliation(s)
- Richa Sharma
- Department of Anesthesia, University of Toronto, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Pirjo Manninen
- Department of Anesthesia, University of Toronto, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
| | - Lashmikumar Venkatraghavan
- Department of Anesthesia, University of Toronto, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada
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Carrabba G, Venkatraghavan L, Bernstein M. Day Surgery Awake Craniotomy for Removing Brain Tumours: Technical Note Describing a Simple Protocol. ACTA ACUST UNITED AC 2008; 51:208-10. [DOI: 10.1055/s-2008-1073132] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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