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Minhas JS, Panerai RB, Swienton D, Robinson TG. Feasibility of improving cerebral autoregulation in acute intracerebral hemorrhage (BREATHE-ICH) study: Results from an experimental interventional study. Int J Stroke 2019; 15:627-637. [DOI: 10.1177/1747493019873690] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Background Cerebral autoregulation is impaired in a multitude of neurological conditions. Increasingly, clinical studies are correlating the nature of this impairment with prognostic markers. In acute intracerebral hemorrhage, impairment of cerebral autoregulation has been associated with worsening clinical outcomes including poorer Glasgow Coma Score and larger hematoma volume. Hypocapnia has been shown to improve cerebral autoregulation despite concerns over hypoperfusion and consequent ischemic risks, and it is therefore hypothesized that hypocapnia (via hyperventilation) in acute intracerebral hemorrhage may improve cerebral autoregulation and consequently clinical outcome. Aims To assess the feasibility and acceptability of the first cerebral autoregulation-targeted intervention in acute intracerebral hemorrhage utilizing a simple bed-side hyperventilatory maneuver. Methods Twelve patients with acute intracerebral hemorrhage within 48 h of onset were enrolled. The experimental setup measured cerebral blood flow velocity (transcranial Doppler), blood pressure (Finometer), and end-tidal CO2 (EtCO2, capnography) at baseline, and in response to hypocapnia (−5 mmHg below baseline) achieved via a 90-s hyperventilatory maneuver. Cerebral autoregulation was evaluated with transfer function analysis and autoregulatory index calculations. Results We observed tolerance to the protocol in a cohort of mild (National Institutes of Health Scale 4) supratentorial intracerebral hemorrhage patients with small volume hematomas without intraventricular extension. Importantly, a significant difference was noted between ipsilateral autoregulatory index at baseline 4.8 (1.7) and autoregulatory index during hypocapnic intervention 7.0 (0.8) (p = 0.0004), reflecting improved cerebral autoregulation, though a dose-dependent effect of EtCO2 on autoregulatory index was not observed. Conclusions In this small study, there was no observed effect on 14-day death and disability in recruited participants. This is the first report of improvement in cerebral autoregulation in acute intracerebral hemorrhage using a non-invasive interventional maneuver, through induction of hypocapnia via hyperventilation. ClinicalTrials.gov Identifier: NCT03324321 URL: https://clinicaltrials.gov/ct2/show/NCT03324321
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Affiliation(s)
- Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Ronney B Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
- National Institute for Health Research Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - David Swienton
- Department of Radiology, University Hospitals of Leicester, Leicester, UK
| | - Thompson G Robinson
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
- National Institute for Health Research Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
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Do acute stroke patients develop hypocapnia? A systematic review and meta-analysis. J Neurol Sci 2019; 402:30-39. [DOI: 10.1016/j.jns.2019.04.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 04/12/2019] [Accepted: 04/29/2019] [Indexed: 12/14/2022]
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Minhas JS, Kennedy C, Robinson TG, Panerai RB. Different strategies to initiate and maintain hyperventilation: their effect on continuous estimates of dynamic cerebral autoregulation. Physiol Meas 2019; 40:015003. [PMID: 30577035 DOI: 10.1088/1361-6579/aafab6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Capnography is a key monitoring intervention in several neurologically vulnerable clinical states. Cerebral autoregulation (CA) describes the ability of the cerebrovascular system to maintain a near constant cerebral blood flow throughout fluctuations in systemic arterial blood pressure, with the partial pressure of arterial carbon dioxide known to directly influence CA. Previous work has demonstrated dysautoregulation lasting around 30 s prior to the anticipated augmentation of hyperventilation-associated hypocapnia. In order assess to potential benefit of hypocapnic interventions in an acute stroke setting, minimisation of dysregulation is paramount. APPROACH Hyperventilation strategies to induce and maintain hypocapnia were performed in 61 healthy participants, effects on temporal estimates of dynamic cerebral autoregulation (autoregulation index, ARI) were assessed to validate the most effective strategy for inducing and maintaining hypocapnia. MAIN RESULTS The extent of initial decrease was significantly smaller in the continuous metronome strategy compared to the delayed metronome and voluntary strategies (▵ARI 0.33 ± 1.18, 2.80 ± 3.33 and 3.69 ± 2.79 respectively, p < 0.017). SIGNIFICANCE The use of a continuous metronome to induce hypocapnia rather than the sudden inception of an auditory stimulus appears to reduce the initial decrease in autoregulatory capacity seen in previous studies. Dysautoregulation can be minimised by continuous metronome use during hyperventilation-induced hypocapnia. This advancement in understanding of the behaviour of CA during hypocapnia permits safer delivery of CA targeted interventions, particularly in neurologically vulnerable patient populations.
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Affiliation(s)
- Jatinder S Minhas
- Department of Cardiovascular Sciences, Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Cardiovascular Sciences Research Group, University of Leicester, Leicester, United Kingdom. Department of Cardiovascular Sciences, University of Leicester, Leicester LE2 7LX, United Kingdom. Author to whom any correspondence should be addressed
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Minhas JS, Panerai RB, Robinson TG. Feasibility of Improving Cerebral Autoregulation in Acute Intracerebral Haemorrhage (BREATHE-ICH) study: a protocol for an experimental interventional study. BMJ Open 2018; 8:e020758. [PMID: 29593024 PMCID: PMC5875592 DOI: 10.1136/bmjopen-2017-020758] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
INTRODUCTION Cerebral autoregulation (CA) is impaired in a multitude of neurological conditions. Increasingly, clinical studies are correlating the nature of this impairment with prognostic markers. In acute intracerebral haemorrhage (ICH), impairment of CA has been associated with worsening clinical outcomes including poorer Glasgow Coma Score and larger haematoma volume. Hypocapnia has been shown to improve CA despite concerns over hypoperfusion and consequent ischaemic risks, and it is therefore hypothesised that hypocapnia (via hyperventilation) in acute ICH may improve CA and consequently clinical outcome. BREATHE-ICH is a CA-targeted interventional study in acute ICH utilising a simple bedside hyperventilatory manoeuvre. METHODS AND ANALYSIS Patients with acute ICH within 48 hours of onset will be included. The experimental set-up measures cerebral blood flow (cerebral blood velocity, transcranial Doppler), blood pressure (Finometer) and end tidal carbon dioxide (capnography) at baseline, and in response to hypocapnia (-5 mm and -10 mm Hg below baseline) achieved via a 90 s hyperventilatory manoeuvre. Autoregulation is evaluated with transfer function analysis and autoregulatory index calculations. Important classical endpoints associated with this before and after interventional study include death and disability at 14 days and the proportion of recruited individuals able to comply with the full measurement protocol. ETHICS AND DISSEMINATION A favourable opinion was granted by the East Midlands-Nottingham 1 Research Ethics Committee (17/EM/0283). It is anticipated that the results of this study will be presented at national and international meetings, with reports being published in journals during late 2018. TRIAL REGISTRATION NUMBER NCT03324321.
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Affiliation(s)
- Jatinder S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
| | - Ronney B Panerai
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
- National Institute for Health Research Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
| | - Thompson G Robinson
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHiASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
- National Institute for Health Research Leicester Biomedical Research Centre, University of Leicester, Leicester, UK
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Sassaroli A, Kainerstorfer JM, Fantini S. Nonlinear extension of a hemodynamic linear model for coherent hemodynamics spectroscopy. J Theor Biol 2015; 389:132-45. [PMID: 26555847 DOI: 10.1016/j.jtbi.2015.11.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 10/08/2015] [Accepted: 11/02/2015] [Indexed: 11/25/2022]
Abstract
In this work, we are proposing an extension of a recent hemodynamic model (Fantini, 2014a), which was developed within the framework of a novel approach to the study of tissue hemodynamics, named coherent hemodynamics spectroscopy (CHS). The previous hemodynamic model, from a signal processing viewpoint, treats the tissue microvasculature as a linear time-invariant system, and considers changes of blood volume, capillary blood flow velocity and the rate of oxygen diffusion as inputs, and the changes of oxy-, deoxy-, and total hemoglobin concentrations (measured in near infrared spectroscopy) as outputs. The model has been used also as a forward solver in an inversion procedure to retrieve quantitative parameters that assess physiological and biological processes such as microcirculation, cerebral autoregulation, tissue metabolic rate of oxygen, and oxygen extraction fraction. Within the assumption of "small" capillary blood flow velocity oscillations the model showed that the capillary and venous compartments "respond" to this input as low pass filters, characterized by two distinct impulse response functions. In this work, we do not make the assumption of "small" perturbations of capillary blood flow velocity by solving without approximations the partial differential equation that governs the spatio-temporal behavior of hemoglobin saturation in capillary and venous blood. Preliminary comparison between the linear time-invariant model and the extended model (here identified as nonlinear model) are shown for the relevant parameters measured in CHS as a function of the oscillation frequency (CHS spectra). We have found that for capillary blood flow velocity oscillations with amplitudes up to 10% of the baseline value (which reflect typical scenarios in CHS), the discrepancies between CHS spectra obtained with the linear and nonlinear models are negligible. For larger oscillations (~50%) the linear and nonlinear models yield CHS spectra with differences within typical experimental errors, but further investigation is needed to assess the effect of these differences. Flow oscillations larger than 10-20% are not typically induced in CHS; therefore, the results presented in this work indicate that a linear hemodynamic model, combined with a method to elicit controlled hemodynamic oscillations (as done for CHS), is appropriate for the quantitative assessment of cerebral microcirculation.
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Affiliation(s)
- Angelo Sassaroli
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, United States.
| | - Jana M Kainerstorfer
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, United States
| | - Sergio Fantini
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, United States
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Pappas A, Shankaran S, Laptook AR, Langer JC, Bara R, Ehrenkranz RA, Goldberg RN, Das A, Higgins RD, Tyson JE, Walsh MC. Hypocarbia and adverse outcome in neonatal hypoxic-ischemic encephalopathy. J Pediatr 2011; 158:752-758.e1. [PMID: 21146184 PMCID: PMC3229432 DOI: 10.1016/j.jpeds.2010.10.019] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2010] [Revised: 09/10/2010] [Accepted: 10/15/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To evaluate the association between early hypocarbia and 18- to 22-month outcome among neonates with hypoxic-ischemic encephalopathy. STUDY DESIGN Data from the National Institute of Child Health and Human Development Neonatal Research Network randomized, controlled trial of whole-body hypothermia for neonatal hypoxic-ischemic encephalopathy were used for this secondary observational study. Infants (n = 204) had multiple blood gases recorded from birth to 12 hours of study intervention (hypothermia versus intensive care alone). The relationship between hypocarbia and outcome (death/disability at 18 to 22 months) was evaluated by unadjusted and adjusted analyses examining minimum PCO(2) and cumulative exposure to PCO(2) <35 mm Hg. The relationship between cumulative PCO(2) <35 mm Hg (calculated as the difference between 35 mm Hg and the sampled PCO(2) multiplied by the duration of time spent <35 mm Hg) and outcome was evaluated by level of exposure (none-high) using a multiple logistic regression analysis with adjustments for pH, level of encephalopathy, treatment group (± hypothermia), and time to spontaneous respiration and ventilator days; results were expressed as odds ratios and 95% confidence intervals. Alternative models of CO(2) concentration were explored to account for fluctuations in CO(2). RESULTS Both minimum PCO(2) and cumulative PCO(2) <35 mm Hg were associated with poor outcome (P < .05). Moreover, death/disability increased with greater cumulative exposure to PCO(2) <35 mm Hg. CONCLUSIONS Hypocarbia is associated with poor outcome after hypoxic-ischemic encephalopathy.
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Affiliation(s)
- Athina Pappas
- Department of Pediatrics, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Seetha Shankaran
- Department of Pediatrics, Wayne State University School of Medicine, Detroit MI
| | - Abbot R. Laptook
- Department of Pediatrics, Women and Infants’ Hospital, Brown University, Providence RI
| | - John C. Langer
- Statistics and Epidemiology, RTI International, Research Triangle Park, NC
| | - Rebecca Bara
- Department of Pediatrics, Wayne State University School of Medicine, Detroit MI
| | | | | | - Abhik Das
- Statistics and Epidemiology, RTI International, Research Triangle Park, NC
| | - Rosemary D. Higgins
- Pregnancy and Perinatology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health
| | - Jon E. Tyson
- Department of Pediatrics, University of Texas Medical School at Houston
| | - Michele C. Walsh
- Department of Pediatrics, Rainbow Babies & Children’s Hospital, Case Western Reserve University, Cleveland OH
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Ma X, Bay-Hansen R, Hauerberg J, Knudsen GM, Olsen NV, Juhler M. Effect of Graded Hyperventilation on Cerebral Metabolism in a Cisterna Magna Blood Injection Model of Subarachnoid Hemorrhage in Rats. J Neurosurg Anesthesiol 2006; 18:18-23. [PMID: 16369136 DOI: 10.1097/01.ana.0000186523.96425.e6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In subarachnoid hemorrhage (SAH) with cerebrovascular instability, hyperventilation may induce a risk of inducing or aggravating cerebral ischemia. We measured cerebral blood flow (CBF) and cerebral metabolic rates of oxygen (CMRO2), glucose (CMRglc), and lactate (CMRlac) at different PaCO2 levels after experimental SAH in rats (injection of 0.07 mL of autologous blood into the cisterna magna). Four groups of Sprague-Dawley male rats were studied at predetermined PaCO2 levels: group A: normocapnia (5.01-5.66 kPa [38.0-42.0 mm Hg]); group B: slight hyperventilation (4.34-5.00 kPa [32.5-37.5 mm Hg]); group C: moderate hyperventilation (3.67-4.33 kPa [27.5-32.4 mm Hg]); group D: profound hyperventilation (3.00-3.66 kPa [22.5-27.4 mm Hg]). Each of the four groups included eight rats with SAH and eight sham-operated controls. CBF was determined by the intracarotid Xe method; CMRo2, CMRglc, and CMRlac were obtained by cerebral arteriovenous differences. In both SAH rats and controls, hyperventilation decreased CBF in proportion to the decrement in PaCO2 without affecting either CMRO2, CMRglc, or CMRlac. In groups C and D, CBF decreased by 20%-35%, but CMRs were maintained by a compensatory increase in oxygen extraction fraction (OEF). The results show that even profound hyperventilation in this model of SAH is associated with an adequate increase in OEF so that CMRs of oxygen, glucose, and lactate remain similar to levels observed in normocapnic conditions.
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Affiliation(s)
- Xiaodong Ma
- Department of Neurosurgery, Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
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Werner C, Lu H, Engelhard K, Unbehaun N, Kochs E. Sevoflurane Impairs Cerebral Blood Flow Autoregulation in Rats: Reversal by Nonselective Nitric Oxide Synthase Inhibition. Anesth Analg 2005; 101:509-516. [PMID: 16037169 DOI: 10.1213/01.ane.0000160586.71403.a4] [Citation(s) in RCA: 20] [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
UNLABELLED In this study, we investigated the effects of 1.0 and 2.0 minimum alveolar anesthetic concentration (MAC) sevoflurane on cerebral blood flow (CBF) autoregulation before and after nonselective inhibition of nitric oxide (NO) synthase in rats. Rats were randomly assigned as follows: Group 1 (n = 8): 1.0 MAC sevoflurane; Groups 2 and 3 (n = 8 per group): 2.0 MAC sevoflurane. Assessment of autoregulation within a mean arterial blood pressure range of 140-60 mm Hg was performed by graded hemorrhage before and after administration of l-arginine methyl ester (l-NAME, 30 mg/kg IV, Groups 1 and 2) or during hypocapnia (Group 3). In 10 additional animals, brain tissue NO(2)(-) concentrations were measured at 1.0 and 2.0 MAC sevoflurane. CBF autoregulation was maintained with 1.0 MAC sevoflurane (Group 1) regardless of NO synthase status indicating that CBF autoregulation might not be related to NO availability. Sevoflurane dose-dependently increased brain tissue NO(2)(-) and impaired CBF autoregulation. Administration of l-NAME (Group 2) but not hypocapnia (Group 3) restored CBF autoregulation. This suggests that sevoflurane impairs the autoregulatory capacity secondary to an increase of the perivascular NO availability and questions the importance of basal cerebrovascular tone in terms of vasodilatory capacity during hypotensive challenges. IMPLICATIONS The present study suggests that the volatile anesthetic sevoflurane dose-dependently impairs cerebrovascular autoregulation by mechanisms secondary to increase of perivascular nitric oxide availability.
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Affiliation(s)
- Christian Werner
- *Klinik für Anästhesiologie, Johannes Gutenberg-Universität, Mainz; †Klinik für Anaesthesiologie and ‡Chirurgische Klinik und Poliklinik, Technische Universität, München, Germany
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McCulloch TJ, Boesel TW, Lam AM. The Effect of Hypocapnia on the Autoregulation of Cerebral Blood Flow During Administration of Isoflurane. Anesth Analg 2005; 100:1463-1467. [PMID: 15845706 DOI: 10.1213/01.ane.0000148623.06596.7e] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Isoflurane impairs autoregulation of cerebral blood flow in a dose-related manner. Previous investigations in several other conditions have demonstrated that impaired autoregulation can be restored by hyperventilation. We hypothesized that hypocapnia may restore cerebral autoregulation impaired by isoflurane anesthesia. We administered isoflurane in 100% oxygen to 12 healthy patients aged 21-59 yr scheduled for elective nonneurological surgery. Isoflurane end-tidal concentration was individualized at 0.1% to 0.2% less than that required to induce short periods of isoelectric electroencephalogram. This resulted in an end-tidal isoflurane concentration of 1.6% +/- 0.2% (mean +/- sd) corresponding to an age-adjusted minimum alveolar anesthetic concentration multiple of 1.4. Mean arterial blood pressure was reduced to <80 mm Hg, by infusion of remifentanil if required. Cerebral autoregulation was assessed by infusing phenylephrine to increase mean arterial blood pressure to 100 mm Hg while monitoring middle cerebral artery blood flow velocity with transcranial Doppler ultrasonography. The change in flow velocity was used to calculate the autoregulation index (ARI). The ARI ranges between 0 and 1 and an ARI < or =0.4 indicates significantly impaired autoregulation. Autoregulation was tested twice in randomized order: once during normocapnia (Paco(2) 38-43 mm Hg) and once during hypocapnia (Paco(2) 27-34 mm Hg). The median (interquartile range) ARI was 0.29 (0.23-0.64) during normocapnia and 0.77 (0.70-0.78) during hypocapnia (P < 0.005). Of the 12 subjects, autoregulation was significantly impaired in 8 subjects during normocapnia and none during hypocapnia (P = 0.001). Hypocapnia restored cerebral autoregulation in normal subjects during isoflurane-induced impairment of autoregulation.
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Affiliation(s)
- Timothy J McCulloch
- *Department of Anaesthetics, Royal Prince Alfred Hospital and †University of Sydney, Sydney, Australia; and ‡Department of Anesthesiology, University of Washington School of Medicine, Seattle, Washington
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Tonnesen J, Pryds A, Larsen EH, Paulson OB, Hauerberg J, Knudsen GM. Laser Doppler flowmetry is valid for measurement of cerebral blood flow autoregulation lower limit in rats. Exp Physiol 2005; 90:349-55. [PMID: 15653714 DOI: 10.1113/expphysiol.2004.029512] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Laser Doppler flowmetry (LDF) is a recent technique that is increasingly being used to monitor relative changes in cerebral blood flow whereas the intra-arterial 133xenon injection technique is a well-established method for repeated absolute measurements of cerebral blood flow. The aim of this study was to validate LDF for assessment of cerebral autoregulation and CO2 reactivity with the 133xenon injection technique as the gold standard. Simultaneous measurements of cerebral blood flow (CBF) were collected by LDF (CBF(LDF)) and the 133xenon method (CBF(Xe)) while (1) cerebral autoregulation was challenged by controlled systemic haemorrhage, or (2) cerebral blood flow was varied by manipulating the arterial partial pressure of CO2 (P(a,CO2)). LDF slightly overestimated CBF under conditions of haemorrhagic shock and haemodilution caused by controlled haemorrhage (paired t test, P < 0.05). However for pooled data, the autoregulation lower limit was similar when determined with the 133xenon and the LDF techniques: 65 +/- 3.9 mmHg and 60 +/- 5.6 mmHg, respectively. Linear regression analysis yielded CBF(Xe) = (1.02 x CBF(LDF)) + 9.1 and r = 0.90. Even for substantial changes in P(a,CO2), the two methods resulted in similar results. We conclude that even though LDF overestimated CBF during haemorrhagic shock caused by controlled haemorrhage, the lower limit autoregulation was correctly identified. The laser Doppler technique provides a reliable method for detection of a wide range of cerebral blood flow changes under CO2 challenge. Haemodilution influences the two methods differently causing relative overestimation of blood flow by the laser Doppler technique compared to the 1(33)xenon method.
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Affiliation(s)
- Jan Tonnesen
- Neurobiology Research Unit, N9201, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, DK- 2100 Copenhagen, Denmark
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Joseph M, Ziadi S, Nates J, Dannenbaum M, Malkoff M. Increases in Cardiac Output Can Reverse Flow Deficits from Vasospasm Independent of Blood Pressure: A Study Using Xenon Computed Tomographic Measurement of Cerebral Blood Flow. Neurosurgery 2003; 53:1044-51; discussion 1051-2. [PMID: 14580270 DOI: 10.1227/01.neu.0000088567.59324.78] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2003] [Accepted: 07/11/2003] [Indexed: 11/19/2022] Open
Abstract
Abstract
INTRODUCTION
Vasospasm after subarachnoid hemorrhage remains a management challenge. The accepted treatment involves hypertensive, hypervolemic, hemodilution therapy. However, there is variation in the application of this treatment. Most authors increase mean arterial pressure (MAP), which can be associated with significant morbidity. Others increase cardiac output (CO). In this study, we examined the relationship between volume status, CO, and MAP and cerebral blood flow (CBF) in the setting of vasospasm.
METHODS
A xenon blood flow tomography-based system was used to quantitate CBF. Sixteen patients with vasospasm after subarachnoid hemorrhage were treated with hypervolemia, phenylephrine to increase MAP, or dobutamine to increase CO. Direct CBF measurements were obtained before and after treatment. A strength of this study is that only one variable (central venous pressure, MAP, or CO) was manipulated in each patient, and the effect of this change was measured immediately.
RESULTS
With phenylephrine, mean MAP increased from 102.4 to 132.1 mm Hg. In regions of diminished CBF due to vasospasm, mean CBF increased from 19.2 to 33.7 ml/100 g/min. Similarly, dobutamine increased the cardiac index from a mean of 4.1 to 6.0 L/min/m2 and slightly decreased MAP. CBF increased from a mean of 24.8 to 35.4 ml/100 g/min. Both were statistically significant changes. With hypervolemia, the average central venous pressure increased from a mean of 5.4 to 7.3 cm H2O; no changes in mean CBF were noted.
CONCLUSION
This article reports the first human study that shows with direct measurements the independent influence of CO in the setting of vasospasm. Increases in CO without changes in MAP can elevate CBF. This finding has immediate clinical application because CO manipulation is much safer than increasing MAP. Because both interventions were equally efficacious, our protocol has been changed to augment CO as a first measure. Induced hypertension is reserved for patients in whom this initial treatment fails.
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Affiliation(s)
- Mathew Joseph
- Department of Neurosurgery, University of Texas Health Science Center, Houston, Texas, USA.
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Cook N. Respiratory care in spinal cord injury with associated traumatic brain injury: bridging the gap in critical care nursing interventions. Intensive Crit Care Nurs 2003; 19:143-53. [PMID: 12765634 DOI: 10.1016/s0964-3397(03)00031-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Spinal cord injury (SCI) is a devastating and challenging condition. The events that lead to SCI, such as road traffic accidents, falls, sports and violence [Top. Spinal Cord Inj. Rehabil. 5 (1999) 83], are also the common aetiologies of traumatic brain injury (TBI). It's not surprising then, that 20-50% of those with cervical SCI have TBI [J. Trauma 46 (1999) 450]. The literature pertaining to the management of either injury in isolation is vast, but lacking where the two conditions are experienced together and require distinct adaptations to interventions. Consequently, a gap in the literature exists. This paper focuses on those patients with SCI of the cervical spine with associated head injury, and pay particular attention to respiratory difficulties, and presents interventions required to minimise and treat the effects of such pulmonary compromise.
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Affiliation(s)
- Neal Cook
- Department of Nursing, University of Ulster, Magee Campus, Derry Co., Derry, Northern Ireland.
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Bay-Hansen R, Ma XD, Hauerberg J, Larsen EH, Juhler M. Effects of cerebrospinal fluid acidity on cerebral blood flow and autoregulation in rats. J Neurosurg Anesthesiol 2003; 15:110-8. [PMID: 12657996 DOI: 10.1097/00008506-200304000-00008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Using a ventriculocisternal perfusion method, the effects of cerebrospinal fluid (CSF) acidity of nonrespiratory origin on cerebral blood flow (CBF) and autoregulation of CBF were investigated. Three groups (six rats each) were studied: one group of sham operated rats, one control group with ventriculocisternal perfusion at normal pH (mean inflow pH +/- SD, 7.42 +/- 0.02), and one experimental group with ventriculocisternal perfusion at low pH (mean inflow pH +/- SD, 6.81 +/- 0.01). CBF was measured by the intracarotid xenon 133 method. Autoregulation was studied by repetitive measurements of CBF during an initial increase and then stepwise reduction of mean arterial blood pressure (MABP). No difference in CBF was found between sham operated and control rats with unperturbed pH (mean cisternal outflow pH +/- SD, 7.42 +/- 0.03) of CSF), and autoregulation was intact in both groups. In the experimental group, the mean CBF +/- SD was increased by 58%, from 127 +/- 33 mL/(100 g.min) before ventriculocisternal perfusion to 201 +/- 54 mL/(100 g.min) (P <.00001) during perfusion with acid CSF (mean cisternal outflow pH +/- SD, 7.23 +/- 0.04). In this group, the relationship between CBF and MABP was linear, thus indicating disrupted autoregulation. In conclusion, CSF acidity significantly increases CBF and impairs autoregulation of CBF.
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Affiliation(s)
- Rikke Bay-Hansen
- Department of Neurosurgery and the Neurobiology Research Unit, Rigshospitalet, Denmark
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Schaller C, Nakase H, Kotani A, Nishioka T, Meyer B, Sakaki T. Impairment of autoregulation following cortical venous occlusion in the rat. Neurol Res 2002; 24:210-4. [PMID: 11877906 DOI: 10.1179/016164102101199620] [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] [Indexed: 10/31/2022]
Abstract
Recent experiments showed an upward shift of the lower limit of autoregulation (AR) following photochemical occlusion of cortical veins in the rat. The goal of the present study was to prove the hypothesis that occlusion of cortical veins will be associated with impairment of the upper limit of autoregulation as well. In n = 28 Wistar rats unilateral frontoparietal cranial windows were drilled for transdural assessment of regional cerebral blood flow (rCBF) by laser Doppler scanning. The animals were allotted to two groups: (1) Group A (n = 5), control group for determination of the upper limit of autoregulation with stepwise induced arterial hypertension by intravenous administration of the alpha adrenergic drug methoxamine under continuous monitoring of mean arterial blood pressure (MABP); (2) Group B (n = 23), in which two cortical veins were photochemically occluded with rose bengal dye and fiberoptic illumination upon baseline CBF measurement. This was followed by repeated rCBF measurements under AR testing. Loss of AR in control Group A with passive increase of rCBF occurred at MABP of 147.5 +/- 2.9 mmHg. In Group B venous occlusion was followed by an initial phase of reduced rCBF, and then by pressure passive increases, thereby indicating loss of AR. Statistically significant changes of rCBF when compared to baseline MABP occurred at MABPbaseline + 10% (112.7 +/- 6.6 mmHg). We conclude that AR is impaired upon cortical venous occlusion with the propensity for hyperperfusion injury at a lower level of MABP when compared with a control group. In the context with earlier findings this may lead to narrowing of the corridor for MABP management following intra-operative occlusion of large cortical veins.
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Affiliation(s)
- Carlo Schaller
- Department of Neurosurgery, University of Bonn, Germany.
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Springborg JB, Ma X, Rochat P, Knudsen GM, Amtorp O, Paulson OB, Juhler M, Olsen NV. A single subcutaneous bolus of erythropoietin normalizes cerebral blood flow autoregulation after subarachnoid haemorrhage in rats. Br J Pharmacol 2002; 135:823-9. [PMID: 11834631 PMCID: PMC1573185 DOI: 10.1038/sj.bjp.0704521] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Systemic administration of recombinant erythropoietin (EPO) has been demonstrated to mediate neuroprotection. This effect of EPO may in part rely on a beneficial effect on cerebrovascular dysfunction leading to ischaemic neuronal damage. We investigated the in vivo effects of subcutaneously administered recombinant EPO on impaired cerebral blood flow (CBF) autoregulation after experimental subarachnoid haemorrhage (SAH). Four groups of male Sprague-Dawley rats were studied: group A, sham operation plus vehicle; group B, sham operation plus EPO; group C, SAH plus vehicle; group D, SAH plus EPO. SAH was induced by injection of 0.07 ml of autologous blood into the cisterna magna. EPO (400 iu kg(-1) s.c.) or vehicle was given immediately after the subarachnoid injection of blood or saline. Forty-eight hours after the induction of SAH, CBF autoregulatory function was evaluated using the intracarotid (133)Xe method. CBF autoregulation was preserved in both sham-operated groups (lower limits of mean arterial blood pressure: 91+/-3 and 98+/-3 mmHg in groups A and B, respectively). In the vehicle treated SAH-group, autoregulation was abolished and the relationship between CBF and blood pressure was best described by a single linear regression line. A subcutaneous injection of EPO given immediately after the induction of SAH normalized autoregulation of CBF (lower limit in group D: 93+/-4 mmHg, NS compared with groups A and B). Early activation of endothelial EPO receptors may represent a potential therapeutic strategy in the treatment of cerebrovascular perturbations after SAH.
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Affiliation(s)
- Jacob Bertram Springborg
- Department of Neuroanaesthesia, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - XiaoDong Ma
- Department of Neurosurgery, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Per Rochat
- Department of Neurosurgery, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Gitte Moos Knudsen
- The Neurobiology Research Unit, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Ole Amtorp
- Department of Pharmacology, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Olaf B Paulson
- The Neurobiology Research Unit, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Marianne Juhler
- Department of Neurosurgery, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Niels Vidiendal Olsen
- Department of Neuroanaesthesia, The Neuroscience Center, Copenhagen University Hospital (Rigshospitalet), Copenhagen, Denmark
- Author for correspondence:
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