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Crofts A, Kelly ME, Gibson CL. Imaging Functional Recovery Following Ischemic Stroke: Clinical and Preclinical fMRI Studies. J Neuroimaging 2019; 30:5-14. [PMID: 31608550 PMCID: PMC7003729 DOI: 10.1111/jon.12668] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 09/12/2019] [Accepted: 09/25/2019] [Indexed: 12/18/2022] Open
Abstract
Disability and effectiveness of physical therapy are highly variable following ischemic stroke due to different brain regions being affected. Functional magnetic resonance imaging (fMRI) studies of patients in the months and years following stroke have given some insight into how the brain recovers lost functions. Initially, new pathways are recruited to compensate for the lost region, showing as a brighter blood oxygen‐level‐dependent (BOLD) signal over a larger area during a task than in healthy controls. Subsequently, activity is reduced to baseline levels as pathways become more efficient, mimicking the process of learning typically seen during development. Preclinical models of ischemic stroke aim to enhance understanding of the biology underlying recovery following stroke. However, the pattern of recruitment and focusing seen in humans has not been observed in preclinical fMRI studies that are highly variable methodologically. Resting‐state fMRI studies show more consistency; however, there are still confounding factors to address. Anesthesia and method of stroke induction are the two main sources of variability in preclinical studies; improvements here can reduce variability and increase the intensity and reproducibility of the BOLD response detected by fMRI. Differences in task or stimulus and differences in analysis method also present a source of variability. This review compares clinical and preclinical fMRI studies of recovery following stroke and focuses on how refinement of preclinical models and MRI methods may obtain more representative fMRI data in relation to human studies.
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Affiliation(s)
- Andrew Crofts
- Department of Neuroscience, Psychology and Behaviour, University of Leicester, Leicester, UK
| | - Michael E Kelly
- Preclinical Imaging Facility, Core Biotechnology Services, University of Leicester, Leicester, UK
| | - Claire L Gibson
- School of Psychology, University of Nottingham, Nottingham, UK
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Kwon KH, Bae H, Kang HG, In J. Hypercapnia does not shorten emergence time from propofol anesthesia: a pilot randomized clinical study. Korean J Anesthesiol 2018; 71:207-212. [PMID: 29690757 PMCID: PMC5995009 DOI: 10.4097/kja.d.18.27068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 09/29/2017] [Accepted: 11/06/2017] [Indexed: 11/18/2022] Open
Abstract
Background The elimination of anesthetic agents is a decisive factor in the emergence from general anesthesia. In this pilot study, we hypothesized that hypercapnia would decrease the emergence time from propofol anesthesia by increasing cardiac output and cerebral blood flow. Methods A total of 32 patients were randomly divided into two groups based on the end-tidal carbon dioxide values: 30 mmHg (the hypocapnia group) and 50 mmHg (the hypercapnia group). Propofol and remifentanil were infused to maintain a bispectral index of 40–50. Remifentanil infusion was stopped 10 min before the discontinuation of propofol. After cessation of propofol infusion, ventilation settings in the hypocapnia group were maintained constant; a rebreathing tube was connected to the respiratory circuit in the hypercapnia group. The time to spontaneous respiration, eye opening (primary endpoint), mouth opening, and tracheal extubation was recorded and analyzed. Results Time to eye opening was 9.7 (1.3) min in the hypocapnia group and 9.0 (1.0) min in the hypercapnia group. The difference in the mean times to eye opening between groups was −0.7 min (95% CI, −4.0 to 2.7, P = 0.688). On multiple regression analysis, there was a significant difference in the mean time to eye opening between males and females. Females recovered about 3.6 min faster than males (95% CI, −6.1 to −1.1, P = 0.009). Conclusions We could not detect a beneficial effect of hypercapnia on propofol emergence time. Irrespective of hypercapnia, females seemed to recover faster than males.
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Affiliation(s)
- Ki-Hyug Kwon
- Department of Anesthesiology and Pain Medicine, Dongguk University Ilsan Hospital, Goyang, Korea
| | - Hansu Bae
- Department of Anesthesiology and Pain Medicine, Dongguk University Ilsan Hospital, Goyang, Korea
| | - Hyun Gu Kang
- Department of Anesthesiology and Pain Medicine, Dongguk University Ilsan Hospital, Goyang, Korea
| | - Junyong In
- Department of Anesthesiology and Pain Medicine, Dongguk University Ilsan Hospital, Goyang, Korea
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Dorr A, Thomason LA, Koletar MM, Joo IL, Steinman J, Cahill LS, Sled JG, Stefanovic B. Effects of voluntary exercise on structure and function of cortical microvasculature. J Cereb Blood Flow Metab 2017; 37:1046-1059. [PMID: 27683451 PMCID: PMC5363487 DOI: 10.1177/0271678x16669514] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Aerobic activity has been shown highly beneficial to brain health, yet much uncertainty still surrounds the effects of exercise on the functioning of cerebral microvasculature. This study used two-photon fluorescence microscopy to examine cerebral hemodynamic alterations as well as accompanying geometric changes in the cortical microvascular network following five weeks of voluntary exercise in transgenic mice endogenously expressing tdTomato in vascular endothelial cells to allow visualization of microvessels irrespective of their perfusion levels. We found a diminished microvascular response to a hypercapnic challenge (10% FiCO2) in running mice when compared to that in nonrunning controls despite commensurate increases in transcutaneous CO2 tension. The flow increase to hypercapnia in runners was 70% lower than that in nonrunners (p = 0.0070) and the runners' arteriolar red blood cell speed changed by only half the amount seen in nonrunners (p = 0.0085). No changes were seen in resting hemodynamics or in the systemic physiological parameters measured. Although a few unperfused new vessels were observed on visual inspection, running did not produce significant morphological differences in the microvascular morphometric parameters, quantified following semiautomated tracking of the microvascular networks. We propose that voluntary running led to increased cortical microvascular efficiency and desensitization to CO2 elevation.
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Affiliation(s)
| | | | | | - Illsung L Joo
- 1 Sunnybrook Research Institute, Toronto, Canada.,2 Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - Joe Steinman
- 2 Department of Medical Biophysics, University of Toronto, Toronto, Canada.,3 Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Canada
| | - Lindsay S Cahill
- 3 Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Canada
| | - John G Sled
- 2 Department of Medical Biophysics, University of Toronto, Toronto, Canada.,3 Mouse Imaging Centre, The Hospital for Sick Children, Toronto, Canada
| | - Bojana Stefanovic
- 1 Sunnybrook Research Institute, Toronto, Canada.,2 Department of Medical Biophysics, University of Toronto, Toronto, Canada
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The hemodynamic response to somatosensory stimulation in mice depends on the anesthetic used: Implications on analysis of mouse fMRI data. Neuroimage 2015; 116:40-9. [DOI: 10.1016/j.neuroimage.2015.05.013] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 04/30/2015] [Accepted: 05/05/2015] [Indexed: 11/23/2022] Open
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Yaraghi A, Golparvar M, Talakoub R, Sateie H, Mehrabi A. Hypercapnic hyperventilation shortens emergence time from Propofol and Isoflurane anesthesia. J Res Pharm Pract 2014; 2:24-8. [PMID: 24991600 PMCID: PMC4076894 DOI: 10.4103/2279-042x.114085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Objective: The aim of this study is to compare the effects of hypercapnic hyperventilation and normocapnic normoventilation on emergence time from propofol and isoflurane anesthesia. Methods: In this clinical trial, the differences in emergence time were evaluated in 80 patients undergoing elective abdominal surgery in Alzahra University hospital, Isfahan, Iran, in 2011-2012. Patients were randomly divided into four groups (groups 1-4) receiving isoflurane hypercapnic hyperventilation, isoflurane normocapnic normoventilation, propofol hypercapnic hyperventilation, and propofol normocapnic normoventilation, respectively. Hypercapnia was maintained by adding CO2 to the patient's inspired gas during hyperventilation. The emergence time and the duration of stay in recovery room in the four groups were measured and compared by one-way analysis of variance (ANOVA) and least significant difference tests. Findings: The average emergence time in groups 1, 2, 3, and 4 were (11.3 ± 3.2), (15.2 ± 3.8), (9 ± 4.2) and (11.8 ± 5.3) min, respectively. These differences were significant (P = 0.001). In patients receiving propofol hypercapnic hyperventilation, the emergence time was faster than in other groups. There was also a significant difference in duration of stay in recovery room between the groups (P = 0.004). Patients who received isoflurane hypercapnic hyperventilation had a shortest length of stay in the recovery room. Conclusion: The emergence time after intravenous anesthesia with propofol can be shortened significantly by using hyperventilation and hypercapnia, without any side effects.
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Affiliation(s)
- Ahmad Yaraghi
- Department of Anesthesia and Critical Care, Anesthesia and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mohammad Golparvar
- Department of Anesthesia and Critical Care, Anesthesia and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Reihanak Talakoub
- Department of Anesthesia and Critical Care, Anesthesia and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Hossein Sateie
- Department of Anesthesia and Critical Care, Anesthesia and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Ali Mehrabi
- Department of Anesthesia and Critical Care, Anesthesia and Critical Care Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
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Abstract
Idiopathic intracranial hypertension (IIH) is a rare headache syndrome characterized by prolonged elevation of intracranial pressure without related pathology in either the brain or the composition of cerebrospinal fluid. Herein, we provide a brief review of the clinical presentation of IIH and the anaesthetic considerations in a female posted for transcervical resection of the endometrium and right nephrectomy with the disorder. Most of patients with IIH are reported during pregnancy and came for management of labour and delivery. To our knowledge no such case has been described previously.
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Affiliation(s)
- Bina P Butala
- Department of Anaesthesia and Critical Care, Smt. K. M. Mehta and Smt. G. R. Doshi Institute of Kidney Diseases and Research Center, Dr. H. L. Trivedi Institute of Transplantation Sciences, Civil Hospital Campus, Asarwa, Ahmedabad, Gujarat, India
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Hedenqvist P, Edner A, Fahlman Å, Jensen-Waern M. Continuous intravenous anaesthesia with sufentanil and midazolam in medetomidine premedicated New Zealand White rabbits. BMC Vet Res 2013; 9:21. [PMID: 23351150 PMCID: PMC3568725 DOI: 10.1186/1746-6148-9-21] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 01/14/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Anaesthesia in rabbits is associated with a high mortality rate, compared to that in cats and dogs. Total intravenous anaesthesia (TIVA) with drugs that provide cardiovascular stability and are rapidly metabolised could be of benefit for use in rabbits. The aim was to evaluate cardiorespiratory effects of TIVA with sufentanil-midazolam in eight New Zealand White rabbits. Subcutaneous premedication with medetomidine (0.1 mg/kg BW) was followed by IV administration of a mixture of 2.5 μg/mL sufentanil and 0.45 mg/mL midazolam at a rate of 0.3 mL/kg BW/h for anaesthetic induction. Additionally, intravenous boluses of 0.1 mL of the mixture were administered every 20 s until the righting reflex was lost. Following endotracheal intubation, anaesthesia was maintained for 60 min with an infusion rate adjusted to supress the pedal withdrawal reflex. Air and oxygen (1:2) were delivered at 3 L/min. Physiological variables were recorded before induction and at predefined time points during and after anaesthesia. RESULTS Righting and pedal withdrawal reflexes were lost within 3 and 5 min, respectively. Doses of sufentanil and midazolam were 0.48 μg/kg BW and 0.09 mg/kg BW for induction, and 0.72 μg/kg BW/h and 0.13 mg/kg BW/h for maintenance. Apnoea occurred in two rabbits. Induction of anaesthesia caused a significant increase in heart rate, cardiac output and arterial CO2 partial pressure and a decrease in mean arterial pressure, respiratory rate and pH. Mean time from stopping the infusion to endotracheal extubation was 5 min, and to return of the righting reflex 7 min. Anaesthesia was characterized by induction and recovery without excitation, with muscle relaxation, and absence of the pedal withdrawal reflex. CONCLUSIONS TIVA with sufentanil-midazolam provided smooth induction and recovery of anaesthesia in rabbits but with marked hypotension and respiratory depression, requiring mechanical ventilation. Further evaluation is needed to establish if the protocol is useful for rabbits undergoing surgery.
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Affiliation(s)
- Patricia Hedenqvist
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, P.O. Box 7054, SE, 750 07, Uppsala, Sweden
| | - Anna Edner
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, P.O. Box 7054, SE, 750 07, Uppsala, Sweden
| | - Åsa Fahlman
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, P.O. Box 7054, SE, 750 07, Uppsala, Sweden
| | - Marianne Jensen-Waern
- Department of Clinical Sciences, Faculty of Veterinary Medicine and Animal Science, Swedish University of Agricultural Sciences, P.O. Box 7054, SE, 750 07, Uppsala, Sweden
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Head-up tilt and hyperventilation produce similar changes in cerebral oxygenation and blood volume: an observational comparison study using frequency-domain near-infrared spectroscopy. Can J Anaesth 2012; 59:357-65. [PMID: 22234820 DOI: 10.1007/s12630-011-9662-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 12/20/2011] [Indexed: 10/14/2022] Open
Abstract
PURPOSE During anesthesia, maneuvers which cause the least disturbance of cerebral oxygenation with the greatest decrease in intracranial pressure would be most beneficial to patients with intracranial hypertension. Both head-up tilt (HUT) and hyperventilation are used to decrease brain bulk, and both may be associated with decreases in cerebral oxygenation. In this observational study, our null hypothesis was that the impact of HUT and hyperventilation on cerebral tissue oxygen saturation (SctO2) and cerebral blood volume (CBV) are comparable. METHODS Surgical patients without neurological disease were anesthetized with propofol-remifentanil. Before the start of surgery, frequency-domain near-infrared spectroscopy was used to measure SctO2 and CBV at the supine position, at the 30° head-up and head-down positions, as well as during hypoventilation and hyperventilation. RESULTS Thirty-three patients were studied. Both HUT and hyperventilation induced small decreases in SctO2 [3.5 (2.6)%; P < 0.001 and 3.0 (1.8)%; P < 0.001, respectively] and in CBV [0.05 (0.07) mL x 100 g(-1); P < 0.001 and 0.06 (0.05) mL x 100 g(-1); P < 0.001, respectively]. There were no differences between HUT to 30° and hyperventilation to an end-tidal carbon dioxide (ETCO2) of 25 mmHg (from 45 mmHg) in both SctO2 (P = 0.3) and CBV (P = 0.4). DISCUSSION The small but statistically significant decreases in both SctO2 and CBV caused by HUT and hyperventilation are comparable. There was no correlation between the decreases in SctO2 and CBV and the decreases in blood pressure and cardiac output during head-up and head-down tilts. However, the decreases in both SctO2 and CBV correlate with the decreases in ETCO2 during ventilation adjustment.
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Franceschini MA, Radhakrishnan H, Thakur K, Wu W, Ruvinskaya S, Carp S, Boas DA. The effect of different anesthetics on neurovascular coupling. Neuroimage 2010; 51:1367-77. [PMID: 20350606 DOI: 10.1016/j.neuroimage.2010.03.060] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 03/01/2010] [Accepted: 03/20/2010] [Indexed: 02/03/2023] Open
Abstract
To date, the majority of neurovascular coupling studies focused on the thalamic afferents' activity in layer IV and the corresponding large spiking activity as responsible for functional hyperemia. This paper highlights the role of the secondary and late cortico-cortical transmission in neurovascular coupling. Simultaneous scalp electroencephalography (EEG) and diffuse optical imaging (DOI) measurements were obtained during multiple conditions of event-related electrical forepaw stimulation in 33 male Sprague-Dawley rats divided into 6 groups depending on the maintaining anesthetic - alpha-chloralose, pentobarbital, ketamine-xylazine, fentanyl-droperidol, isoflurane, or propofol. The somatosensory evoked potentials (SEP) were decomposed into four components and the question of which best predicts the hemodynamic responses was investigated. Results of the linear regression analysis show that the hemodynamic response is best correlated with the secondary and late cortico-cortical transmissions and not with the initial thalamic input activity in layer IV. Baseline cerebral blood flow (CBF) interacts with neural activity and influences the evoked hemodynamic responses. Finally, neurovascular coupling appears to be the same across all anesthetics used.
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Affiliation(s)
- Maria Angela Franceschini
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, USA.
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Propofol allows precise quantitative arterial spin labelling functional magnetic resonance imaging in the rat. Neuroimage 2010; 51:1395-404. [PMID: 20304075 DOI: 10.1016/j.neuroimage.2010.03.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 02/19/2010] [Accepted: 03/09/2010] [Indexed: 11/24/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) techniques highlight cerebral vascular responses which are coupled to changes in neural activation. However, two major difficulties arise when employing these techniques in animal studies. First is the disturbance of cerebral blood flow due to anaesthesia and second is the difficulty of precise reproducible quantitative measurements. These difficulties were surmounted in the current study by using propofol and quantitative arterial spin labelling (QASL) to measure relative cerebral blood volume of labelled water (rCBV(lw),) mean transit time (MTT) and capillary transit time (CTT). The ASL method was applied to measure the haemodynamic response in the primary somatosensory cortex following forepaw stimulation in the rat. Following stimulation an increase in signal intensity and rCBV(lw) was recorded, this was accompanied by a significant decrease in MTT (1.97+/-0.06s to 1.44+/-0.04s) and CTT (1.76+/-0.06s to 1.39+/-0.07s). Two animals were scanned repeatedly on two different experimental days. Stimulation in the first animal was applied to the same forepaw during the initial and repeat scan. In the second animal stimulation was applied to different forepaws on the first and second days. The control and activated ASL signal intensities, rCBVlw on both days were almost identical in both animals. The basal MTT and CTT during the second scan were also very similar to the values obtained during the first scan. The MTT recorded from the animal that underwent stimulation to the same paw during both scanning sessions was very similar on the first and second days. In conclusion, propofol induces little physiological disturbance and holds potential for longitudinal QASL fMRI studies.
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Kadoi Y, Kawauchi C, Saito S, Takahashi K. The comparative effects of equipotent Bispectral Index dosages of propofol and sevoflurane on cerebrovascular carbon dioxide reactivity in elderly patients. J Clin Anesth 2009; 21:173-7. [PMID: 19464609 DOI: 10.1016/j.jclinane.2008.06.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 06/27/2008] [Accepted: 06/29/2008] [Indexed: 10/20/2022]
Abstract
STUDY OBJECTIVES To compare the effects of equipotent Bispectral Index (BIS) doses of propofol and sevoflurane on cerebrovascular carbon dioxide (CO(2)) reactivity in elderly patients. DESIGN Prospective, randomized, controlled study. SETTING University Hospital. PATIENTS 30 consecutive elderly patients (older than 70 yrs of age) scheduled for elective orthopedic, cardiac, or thoracic surgery. INTERVENTIONS Anesthesia was maintained with either sevoflurane or propofol along with 33% oxygen and 67% nitrous oxide. A BIS monitor was used. Sevoflurane and propofol dosages were controlled to maintain BIS values at target levels of 40-45. MEASUREMENTS A 2.5-MHz pulsed transcranial Doppler (TCD) probe was used to measure mean blood flow velocity in the middle cerebral artery (Vmca). After establishing baseline values of Vmca, end-tidal CO(2) was increased by decreasing ventilatory frequency by 4-8 breaths/min. MAIN RESULTS Equipotent doses of 2.25% sevoflurane and 6.61 mg/kg/hr of propofol were required to maintain BIS values at target levels. Baseline blood pressure (BP), BP at hypercapnia, baseline PaCO(2), baseline PaCO(2) at hypercapnia, and pulsatile index were essentially identical between the groups. Absolute and relative CO(2) reactivities in the sevoflurane groups were higher than those in the propofol groups (absolute CO(2) reactivity: 3.2 +/- 0.2* vs. 2.2 +/- 0.3 cm/sec/mmHg; relative CO(2) reactivity: 9.4 +/- 0.3* vs. 7.8 +/- 0.3 cm/sec/mmHg; *P < 0.01 vs. propofol group). CONCLUSIONS In elderly patients, hypercapnia has less effect on cerebral circulation during propofol anesthesia than with sevoflurane.
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Affiliation(s)
- Yuji Kadoi
- Department of Anesthesiology, Gunma University Hospital, Gunma 371-8511, Japan
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Hossmann KA, Traystman RJ. Cerebral blood flow and the ischemic penumbra. HANDBOOK OF CLINICAL NEUROLOGY 2008; 92:67-92. [PMID: 18790270 DOI: 10.1016/s0072-9752(08)01904-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Wang M, Joshi S. Electrocerebral silence after intracarotid propofol injection is a function of transit time. Anesth Analg 2007; 104:1498-503, table of contents. [PMID: 17513649 DOI: 10.1213/01.ane.0000264089.72804.54] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND We hypothesized that the duration of electrocerebral (electroencephalogram, EEG) silence after bolus injection of propofol, a highly lipid soluble anesthetic drug, during transient cerebral hypoperfusion, will be directly related to the time taken by the bolus of drug to transit the cerebral circulation. METHODS We randomly divided 24 New Zealand White rabbits into two propofol volume groups: 0.5 and 0.8 mL groups. In each group, 12 animals received two intracarotid injections of 1% propofol: the first injection was made under normal physiological conditions and the second injection during cerebral hypoperfusion produced by bilateral carotid occlusion and IV bolus injection of adenosine and esmolol. We determined the duration of electrocerebral silence and the transit time of propofol emulsion under both cerebral circulation conditions. The transit time was measured by videomicroscopy through an implanted cranial window. RESULTS Cerebral hypoperfusion increased transit time with both low (2.3 +/- 0.7 to 55.7 +/- 21.4 s, n = 12, P < 0.0001) and high (2.2 +/- 0.6 to 62.5 +/- 31 s, n = 12, P < 0.0001) bolus volumes. The duration of electrocerebral silence during cerebral hypoperfusion was a function of the transit time with low (electrocerebral silence s = 152 + 2.3 x transit time, n = 12, r = 0.73, P = 0.007) and high (electrocerebral silence s = 186 + 3.2 x transit time, n = 12, r = 0.68, P = 0.02) bolus volumes. CONCLUSION These results suggest that manipulation of the transit time of highly lipid-soluble drugs profoundly enhances the effect site delivery.
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Affiliation(s)
- Mei Wang
- Department of Anesthesiology, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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Nakagawa K, Ishibashi T, Matsushima M, Tanifuji Y, Amaki Y, Furuhata H. Does Long-Term Continuous Transcranial Doppler Monitoring Require a Pause for Safer Use? Cerebrovasc Dis 2007; 24:27-34. [PMID: 17519541 DOI: 10.1159/000103113] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Accepted: 12/07/2006] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Transcranial Doppler sonography (TCD) has been used widely for long-term monitoring of cerebral blood flow without adverse reports. However, attention has not been adequately paid to the fact that an increase in the time period of TCD insonation causes brain temperature to rise due to ultrasound absorption by tissue and the skull. We measured the actual temperature rise in local brain tissue induced by TCD insonation over a long time period during in vivo animal experiments in order to verify whether or not a pause is required in long-term, continuous TCD monitoring. METHODS We inserted thermocouples into the skull-brain interface (SBI) of 15 New Zealand White rabbits (10: TCD application group; 5: control group, TCD non-application group). The TCD probe was placed on the parietal bone, and changes in SBI temperature (SBIT) were measured for 90 min. TCD was set at maximum output level (0.2 W, 2 MHz). RESULTS SBIT in the TCD group increased rapidly to 3.47 degrees C within 25 min and then reached a plateau. The maximum time for safe continuous TCD application is estimated to be 33 min. CONCLUSIONS Even though there are large differences in factors, such as brain volume and environmental conditions, between rabbits and humans, there is less difference in their cerebral blood flow per brain weight, which is the parameter that is mainly associated with heat reduction. Accordingly, the findings of the present experiment suggest that long-term TCD monitoring in clinical use should include a pause after every 30 min of insonation to avoid thermal damage to the brain surface.
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Affiliation(s)
- Kiyotaka Nakagawa
- Department of Anesthesiology, ME Laboratory, Research Center for Medical Science, Jikei University School of Medicine, Tokyo, Japan.
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Kadoi Y, Takahashi KI, Saito S, Goto F. The Comparative Effects of Sevoflurane Versus Isoflurane on Cerebrovascular Carbon Dioxide Reactivity in Patients with Diabetes Mellitus. Anesth Analg 2006; 103:168-72, table of contents. [PMID: 16790647 DOI: 10.1213/01.ane.0000221188.09510.75] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The use of volatile anesthetics has been reported to alter cerebrovascular carbon dioxide (CO2) reactivity. We examined the comparative effects of sevoflurane versus isoflurane on cerebrovascular CO2 reactivity in 40 patients with diabetes mellitus. Anesthesia was maintained with either 1.0 minimum alveolar anesthetic concentration of sevoflurane or 1.0 minimum alveolar anesthetic concentration of isoflurane in 33% oxygen and 67% nitrous oxide. A 2.5-MHz pulsed transcranial Doppler probe was attached to the patient's head at the right temporal window for continuous measurement of mean blood flow velocity in the middle cerebral artery. After establishing baseline middle cerebral artery velocity values and cardiovascular hemodynamics, we increased end-tidal CO2 by decreasing ventilatory frequency by 2-5 breaths/min and repeated the measurements. These were then used to calculate absolute and relative CO2 reactivity. Absolute CO2 reactivity was less in insulin-treated patients with either sevoflurane or isoflurane compared with those patients on oral antidiabetic drugs or dietary therapy (sevoflurane group: diet = 2.6 +/- 0.6; oral antidiabetic drug = 2.5 +/- 0.8; insulin = 1.6 +/- 0.8*; isoflurane group: diet = 3.3 +/- i0.7; oral antidiabetic drug = 3.4 +/- 0.7; insulin = 1.9 +/- 0.7* cm.s(-1).mm Hg(-1); *P < 0.05, respectively). Relative CO2 reactivity showed a similar pattern in the diet-controlled and oral antidiabetic groups, absolute and relative CO2 reactivities were lower with sevoflurane versus isoflurane. Hence, we conclude that cerebrovascular CO2 reactivity in insulin-dependent patients is impaired under both sevoflurane and isoflurane anesthesia.
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Affiliation(s)
- Yuji Kadoi
- Department of Anesthesiology, Gunma University, Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
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17
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Abstract
Indomethacin has been suggested as a therapeutic tool to manage elevated intracranial pressure in patients with severe head injury and patients undergoing craniotomy for brain tumors. Indomethacin is a non-selective cyclooxygenase inhibitor. Compared to other cyclooxygenase inhibitors indomethacin has unique effects on cerebral blood flow. Administration of indomethacin causes cerebral vasoconstriction and decreases cerebral blood flow, which elicits a decrease in intracranial pressure. The mechanism of indomethacin-induced cerebral vasoconstriction is not completely understood and controversies exist whether indomethacin causes cerebral ischemia. The primary aims of this article were to review the existing knowledge of indomethacin's influence upon cerebral hemodynamics and elevated ICP in patients with brain pathology. Furthermore, indomethacin's mechanism of action and whether it causes cerebral ischemia are discussed.
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Affiliation(s)
- M Rasmussen
- Department of Neuroanesthesia, Arhus University Hospital, 8000 Arhus C, Denmark.
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18
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Hinohara H, Kadoi Y, Takahashi KI, Saito S, Goto F. Differential effects of propofol on cerebrovascular carbon dioxide reactivity in elderly versus young subjects. J Clin Anesth 2005; 17:85-90. [PMID: 15809122 DOI: 10.1016/j.jclinane.2004.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2003] [Accepted: 05/19/2004] [Indexed: 10/25/2022]
Abstract
STUDY OBJECTIVE To examine the age-related difference between elderly and young patients in the effect of propofol on cerebrovascular carbon dioxide (CO(2)) reactivity. DESIGN Prospective controlled study. SETTING University hospital. PATIENTS Elderly (older than 70 years, n = 13) and young patients (younger than 25 years, n = 13) scheduled for elective orthopedic surgery. INTERVENTIONS After induction of anesthesia, a 2.5-MHz pulsed transcranial Doppler probe was attached to the patient's head at the right temporal window, from which mean blood flow velocity of the middle cerebral artery was measured continuously. MEASUREMENTS After obtaining baseline values of velocity of the middle cerebral artery, arterial blood gases, and cardiovascular hemodynamics, end-tidal CO(2) was decreased by increasing the ventilatory frequency by 2 to 5 breaths per minute. Measurements were repeated when end-tidal CO(2) decreased and remained stable for 5 to 10 minutes. Cerebrovascular CO(2) reactivity, at propofol doses of 5 and 10 mg/kg/h, was measured. MAIN RESULTS No significant differences were observed between the 2 groups in baseline absolute and relative CO(2) reactivity. However, there were significant differences between the 2 groups in absolute or relative CO(2) reactivity at a propofol dosage of 5 mg/kg/h. (Absolute CO(2) reactivity in young patients: 2.1 +/- 0.8 cm/s/mm Hg; elderly: 1.6 +/- 0.4* cm/s/mm Hg. Relative CO(2) reactivity in young patients: 7.4% +/- 1.6%/mm Hg; in the elderly: 6.5% +/- 0.9%*/mm Hg; unpaired t test, *P < .05). In contrast, there were no significant differences between the 2 groups in terms of absolute or relative CO(2) reactivity at a propofol dosage of 10 mg/kg/h. CONCLUSIONS Cerebrovascular CO(2) reactivity in elderly patients was lower than that in young patients at a propofol dosage of 5 mg/kg/h.
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Affiliation(s)
- Hiroshi Hinohara
- Department of Intensive Care, Graduate School of Medicine, Gunma University, Gunma 371-8511, Japan
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19
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Hinohara H, Kadoi Y, Takahashi KI, Saito S, Goto F. Cerebrovascular carbon dioxide reactivity with propofol anesthesia in patients with previous stroke. J Clin Anesth 2004; 16:483-7. [PMID: 15590249 DOI: 10.1016/j.jclinane.2003.11.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2003] [Revised: 11/20/2003] [Accepted: 11/20/2003] [Indexed: 11/28/2022]
Abstract
STUDY OBJECTIVE To examine whether patients with previous stroke have impaired cerebrovascular carbon dioxide (CO2) reactivity when receiving propofol anesthesia. DESIGN Prospective, controlled study. SETTING University hospital. PATIENTS 34 consecutive patients, 17 of whom had previous stroke and were scheduled for elective cardiac surgery, and 17 control age-matched patients without previous stroke who were also scheduled for cardiac surgery. INTERVENTIONS Anesthesia was induced and a 2.5-MHz pulsed transcranial Doppler probe was attached to the patient's head at the right temporal window. Mean blood flow velocity of the middle cerebral artery (Vmca) was measured continuously. MEASUREMENTS After establishing baseline Vmca, arterial blood gases and cardiovascular hemodynamic values, partial pressure of end-tidal CO2 (PETCO2) was increased by changing the ventilatory frequency by 2 to 5 breaths/min. The measurements were repeated when PETCO2 increased and remained stable for 5 to 10 minutes. MAIN RESULTS Values for absolute CO2 reactivity in the control patients and in those with previous stroke were 2.6 +/- 0.5 and 2.9 +/- 0.7 cm/sec/mmHg, respectively, a nonsignificant difference in these values. Values for relative CO2 reactivity in control patients and in patients with previous stroke were 6.4 +/- 1.4 and 6.1 +/- 1.4%/mmHg, respectively, with no significant difference noted. CONCLUSIONS Cerebrovascular CO2 reactivity in patients with previous stroke is normal during propofol anesthesia.
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Affiliation(s)
- Hiroshi Hinohara
- Department of Intensive Care, Gunma University, Graduate School of Medicine, Gunma, Japan
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20
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Packard SD, Mandeville JB, Ichikawa T, Ikeda K, Terada K, Niloff S, Chiocca EA, Rosen BR, Marota JJA. Functional response of tumor vasculature to PaCO2: determination of total and microvascular blood volume by MRI. Neoplasia 2004; 5:330-8. [PMID: 14511404 PMCID: PMC1502420 DOI: 10.1016/s1476-5586(03)80026-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In order to identify differences in functional activity, we compared the reactivity of glioma vasculature and the native cerebral vasculature to both dilate and constrict in response to altered P(a)CO(2). Gliomas were generated by unilateral implantation of U87MGdEGFR human glioma tumor cells into the striatum of adult female athymic rats. Relative changes in total and microvascular cerebral blood volume were determined by steady state contrast agent-enhanced magnetic resonance imaging for transitions from normocarbia to hypercarbia and hypocarbia. Although hypercarbia induced a significant increase in both total and microvascular blood volume in normal brain and glioma, reactivity of glioma vasculature was significantly blunted in comparison to normal striatum; glioma total +/- CBV increased by 0.6 +/- 0.1%/mm Hg CO(2) whereas normal striatum increased by 1.5 +/- 0.2%/mm Hg CO(2), (P <.0001, group t-test). Reactivity of microvascular blood volume was also significantly blunted. In contrast, hypocarbia decreased both total and microvascular blood volumes more in glioma than in normal striatum. These results indicate that cerebral blood vessels derived by tumor-directed angiogenesis do retain reactivity to CO(2). Furthermore, reduced reactivity of tumor vessels to a single physiological perturbation, such as hypercarbia, should not be construed as a generalized reduction of functional activity of the tumor vascular bed.
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Affiliation(s)
- Scott D Packard
- MGH-NMR Center, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
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21
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Rasmussen M, Tankisi A, Cold GE. The effects of indomethacin on intracranial pressure and cerebral haemodynamics in patients undergoing craniotomy: A randomised prospective study. Anaesthesia 2004; 59:229-36. [PMID: 14984519 DOI: 10.1111/j.1365-2044.2004.03604.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We compared the effects of indomethacin (bolus of 0.2 mg.kg-1 followed by an infusion of 0.2 mg.kg-1.h-1) and placebo on intracranial pressure and cerebral haemodynamics in 30 patients undergoing craniotomy for supratentorial brain tumours under propofol and fentanyl anaesthesia. Indomethacin was given before induction of anaesthesia and the infusion was terminated after opening of the dura. Subdural intracranial pressure was measured through the first burr hole and before opening the dura. Cerebral blood flow velocity, cerebral perfusion pressure, jugular bulb oxygen saturation, arterio-venous oxygen difference and carbon dioxide reactivity were measured; dural tension and the degree of brain swelling were estimated. Before induction of anaesthesia, indomethacin administration was associated with a significant decrease in cerebral blood flow velocity compared with placebo. After induction of anaesthesia, cerebral blood flow velocity and mean arterial blood pressure decreased significantly in both groups. Indomethacin was not associated with a decrease in intracranial pressure. There were no differences in cerebral perfusion pressure, dural tension or degree of brain swelling between the two groups. Carbon dioxide reactivity measured after induction of anaesthesia was significantly lower in the indomethacin group (p < 0.05). After removal of the bone flap, no significant difference in carbon dioxide reactivity was observed. We suggest that these findings are explained by propofol-induced cerebral vasoconstriction.
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Affiliation(s)
- M Rasmussen
- Department of Neuroanaesthesia, Aarhus University Hospital, 8000 Aarhus C, Denmark
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22
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Mirzai H, Tekin I, Tarhan S, Ok G, Goktan C. Effect of Propofol and Clonidine on Cerebral Blood Flow Velocity and Carbon Dioxide Reactivity in the Middle Cerebral Artery. J Neurosurg Anesthesiol 2004; 16:1-5. [PMID: 14676561 DOI: 10.1097/00008506-200401000-00001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This study was designed to evaluate the effects of propofol alone and propofol-clonidine combination on human middle cerebral artery blood flow velocity (Vmca) and cerebrovascular carbon dioxide (CO2) response by using transcranial Doppler ultrasonography. Mean Vmca in response to changes in arterial partial pressure of CO2 (Paco2) was determined under the following conditions: awake (group 1), propofol anesthesia (group 2), and combined propofol-clonidine anesthesia (group 3). Normocapnic, hypercapnic, and hypocapnic values of heart rate, mean arterial pressure, partial end-tidal CO2 pressure, Paco2, and Vmca were obtained. The mean Vmca in groups 2 and 3 was significantly lower than that in group 1 at each level of Paco2. The calculated Vmca at each level of Paco2 was not different between groups 2 and 3. There was a correlation between Paco2 and Vmca in all groups, but in the anesthetized groups the effect of Paco2 on Vmca was attenuated. The present data demonstrated that clonidine-propofol does not change CO2 reactivity compared with propofol alone, but both anesthetics attenuate cerebral blood flow compared with awake controls.
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Affiliation(s)
- Hasan Mirzai
- Department of Neurosurgery, Medical Faculty, Celal Bayar University, Manisa, Turkey.
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23
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Kadoi Y, Hinohara H, Kunimoto F, Saito S, Ide M, Hiraoka H, Kawahara F, Goto F. Diabetic patients have an impaired cerebral vasodilatory response to hypercapnia under propofol anesthesia. Stroke 2003; 34:2399-403. [PMID: 12958324 DOI: 10.1161/01.str.0000090471.28672.65] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND PURPOSE The purpose of this study was to examine the effects of diabetes mellitus and its severity on the cerebral vasodilatory response to hypercapnia. METHODS Thirty diabetic patients consecutively scheduled for elective major surgery were studied. After induction of anesthesia, a 2.5-MHz pulsed transcranial Doppler probe was attached to the patient's head at the right temporal window, and mean blood flow velocity of the middle cerebral artery (Vmca) was measured continuously. After the baseline Vmca, arterial blood gases, and cardiovascular hemodynamic values were measured, end-tidal CO2 was increased by reducing ventilatory frequency by 2 to 5 breaths per minute. Measurements were repeated when end-tidal CO2 increased and remained stable for 5 to 10 minutes. RESULTS Significant differences were observed in absolute and relative CO2 reactivity between the diabetes and control groups (absolute CO2 reactivity: control, 2.8+/-0.7; diabetes mellitus, 2.1+/-1.3; P<0.01; relative CO2 reactivity: control, 6.3+/-1.4; diabetes mellitus, 4.5+/-2.7; P<0.01, Mann-Whitney U test). Significant differences were also found between diabetic patients with retinopathy and those without retinopathy in absolute (P=0.002) and relative (P=0.002) CO2 reactivity, glycosylated hemoglobin (P=0.0034), and fasting blood sugar (P=0.01) (Scheffé's test, Mann-Whitney U test). There was an inverse correlation between absolute CO2 reactivity and glycosylated hemoglobin (r=0.69, P<0.001). CONCLUSIONS Insulin-dependent diabetic patients have an impaired vasodilatory response to hypercapnia compared with that of the control group, and the present findings suggest that their degree of impairment is related to the severity of diabetes mellitus.
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Affiliation(s)
- Yuji Kadoi
- Intensive Care Medicine, Gunma University School of Medicine, 3-39-15 Showa-Machi, Maebashi, Gunma 371-8511, Japan.
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24
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Karsli C, Wilson-Smith E, Luginbuehl I, Bissonnette B. The effect of nitrous oxide on cerebrovascular reactivity to carbon dioxide in children during propofol anesthesia. Anesth Analg 2003; 97:694-698. [PMID: 12933387 DOI: 10.1213/01.ane.0000074235.81165.af] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Nitrous oxide (N(2)O) increases cerebral blood flow when used alone and in combination with propofol. We investigated the effects of N(2)O on cerebrovascular CO(2) reactivity (CCO(2)R) during propofol anesthesia in 10 healthy children undergoing elective urological surgery. Anesthesia consisted of a steady-state propofol infusion and a continuous caudal epidural block. A transcranial Doppler probe was used to measure middle cerebral artery blood flow velocity. Randomization determined the sequence order of N(2)O (N(2)O/air or air/N(2)O) and end-tidal (ET)CO(2) concentration (25, 35, 45, and 55 mm Hg) using an exogenous source of CO(2). At steady state, three sets of measurements of middle cerebral artery blood flow velocity, mean arterial blood pressure, and heart rate were recorded. A linear preservation of CCO(2)R was observed above 35 mm Hg of ETCO(2), irrespective of N(2)O. A decrease in CCO(2)R to 1.4%-1.9% per millimeters of mercury was seen in the hypocapnic range (ETCO(2) 25-35 mm Hg) with both air and N(2)O. We conclude that N(2)O does not affect CCO(2)R during propofol anesthesia in children. When preservation of CCO(2)R is required, the combination of N(2)O with propofol anesthesia in children would seem suitable. The cerebral vasoconstriction caused by propofol would imply that hyperventilation to ETCO(2) values less than 35 mm Hg may not be required because no further reduction in cerebral blood flow velocity would be achieved.
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Affiliation(s)
- C Karsli
- Department of Anesthesia, The Hospital for Sick Children and the University of Toronto, Ontario, Canada
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25
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Latchaw RE, Yonas H, Hunter GJ, Yuh WTC, Ueda T, Sorensen AG, Sunshine JL, Biller J, Wechsler L, Higashida R, Hademenos G. Guidelines and recommendations for perfusion imaging in cerebral ischemia: A scientific statement for healthcare professionals by the writing group on perfusion imaging, from the Council on Cardiovascular Radiology of the American Heart Association. Stroke 2003; 34:1084-104. [PMID: 12677088 DOI: 10.1161/01.str.0000064840.99271.9e] [Citation(s) in RCA: 229] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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26
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Myburgh JA, Upton RN, Ludbrook GL, Martinez A, Grant C. Cerebrovascular carbon dioxide reactivity in sheep: effect of propofol or isoflurane anaesthesia. Anaesth Intensive Care 2002; 30:413-21. [PMID: 12180577 DOI: 10.1177/0310057x0203000402] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Propofol and isoflurane are commonly used in neuroanaesthesia. Some published data suggest that the use of these agents is associated with impaired cerebral blood flow/carbon dioxide (CO2) reactivity. Cerebrovascular CO2 reactivity was therefore measured in three cohorts of adult merino sheep: awake (n=6), anaesthetized with steady-state propofol (15 mg/min; n=6) and anaesthetized with 2% isoflurane (n=6). Changes in cerebral blood flow were measured continuously from changes in velocities of blood in the sagittal sinus via a Doppler probe. Alterations in the partial pressure of carbon dioxide in arterial blood (PaCO2) over the range 18-63 mmHg were achieved by altering either the inspired CO2 concentration or the rate of mechanical ventilation. Cerebral blood flow/CO2 relationships were determined by linear regression analysis, with changes in cerebral blood flow expressed as a percentage of the value for a PaCO2 of 35 mmHg. Propofol decreased cerebral blood flow by 55% relative to pre-anaesthesia values (P=0.0001), while isoflurane did not significantly alter cerebral blood flow (88.45% of baseline, P=0.39). Significant linear relationships between cerebral blood flow and CO2 tension were determined in all individual studies (r2 ranged from 0.72 to 0.99). The slopes of the lines were highly variable between individuals for the awake cohort (mean 4.73, 1.42-7.12, 95% CI). The slopes for the propofol (mean 2.67, 2.06-3.28, 95% CI) and isoflurane (mean 2.82, 219-3.45, 95% CI) cohorts were more predictable. However, there was no significant difference between these anaesthetic agents with respect to the CO2 reactivity of cerebral blood flow.
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Affiliation(s)
- J A Myburgh
- Department of Anaesthesia and Intensive Care, University of Adelaide, South Australia
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27
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Affiliation(s)
- Kate Leslie
- Staff Anaesthetist, Department of Anaesthesia and Pain Management, Royal Melbourne Hospital, Melbourne, Australia.
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28
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Cenic A, Craen RA, Lee TY, Gelb AW. Cerebral blood volume and blood flow responses to hyperventilation in brain tumors during isoflurane or propofol anesthesia. Anesth Analg 2002; 94:661-6; table of contents. [PMID: 11867393 DOI: 10.1097/00000539-200203000-00033] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
UNLABELLED Using computerized tomography, we measured absolute cerebral blood flow (CBF) and cerebral blood volume (CBV) in tumor, peri-tumor, and contralateral normal regions, at normocapnia and hypocapnia, in 16 rabbits with brain tumors (VX2 carcinoma), under isoflurane or propofol anesthesia. In both anesthetic groups, CBV and CBF were highest in the tumor region and lowest in the contralateral normal tissue. For isoflurane, a significant decrease in both CBV and CBF was observed in all tissue regions with hyperventilation (P < 0.05), but without accompanying changes in intracranial pressure. However, the percent reduction in regional CBF with hypocapnia was two times larger than that observed in the CBV response (P < 0.01). In contrast, there were no significant changes in CBV and CBF in the Propofol group with hyperventilation for all regions (P > 0.10). In addition, there were no differences between CBV values for isoflurane at hypocapnia when compared with CBV values for propofol at normo- or hypocapnia (P > 0.34 and P > 0.35, respectively, in the tumor regions). Our results indicate that propofol increases cerebral vascular tone in both neoplastic and normal tissue vessels compared with isoflurane. CBV and CBF during normocapnia were significantly greater in all regions (tumor, peri-tumor, and contralateral normal tissue) with isoflurane than with propofol. CBV and CBF remained responsive to hyperventilation only with isoflurane. IMPLICATIONS In rabbits with brain tumors, brain blood flow and volume were significantly larger in all regions (tumor, peri-tumor, and contralateral normal tissue) with isoflurane than with propofol during normocapnia, and remained responsive to a reduction in PaCO(2). Consequently, during hypocapnia, brain blood flow and volume values with isoflurane were similar to values with propofol.
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Affiliation(s)
- Aleksa Cenic
- Department of Radiology, St. Joseph's Health Centre, Imaging Research Laboratories, University of Western Ontario, London, Canada
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