Cerebral Venous Oxygen Saturation Research Articles

Measurement of cerebral venous oxygenation with quantitative susceptibility mapping after subarachnoid hemorrhage: A pilot study.

We measured cerebral venous oxygenation after aneurysmal subarachnoid hemorrhage (aSAH) using quantitative susceptibility mapping (QSM) to explore its relationship with cognitive function. Twenty participants, including 10 patients with aSAH and 10 healthy volunteers as the control group, were included. Patients with aSAH were evaluated at 2days, 3weeks, and 6months after aSAH. Each participant underwent magnetic resonance imaging and completed the Montreal Cognitive Assessment (MoCA) at baseline, midpoint, and endpoint. QSM was used to determine the magnetic susceptibility of the cerebral veins. Furthermore, the relationship between MoCA and oxygen saturation in the cerebral veins was examined. The first scans of the cerebral veins and straight sinus susceptibility were considerably more significant in the aSAH group than in the healthy control group. At the 6-month follow-up, the mean oxygen saturation steadily increased in the aSAH group. Cerebral venous oxygen saturation was moderately correlated with MoCA (r = 0.5319, P = .0025). QSM can be used to measure changes in cerebral venous oxygenation levels in patients with aSAH. During the acute phase of aSAH, there is a reduction in the oxygen saturation in the cerebral veins, and the shift in oxygen saturation levels may correlate with cognitive outcomes in patients with aSAH.

Sleep-stage-dependent alterations in cerebral oxygen metabolism quantified by magnetic resonance.

A key function of sleep is to provide a regular period of reduced brain metabolism, which is critical for maintenance of healthy brain function. The purpose of this work was to quantify the sleep-stage-dependent changes in brain energetics in terms of cerebral metabolic rate of oxygen (CMRO2 ) as a function of sleep stage using quantitative magnetic resonance imaging (MRI) with concurrent electroencephalography (EEG) during sleep in the scanner. Twenty-two young and older subjects with regular sleep hygiene and Pittsburgh Sleep Quality Index (PSQI) in the normal range were recruited for the study. Cerebral blood flow (CBF) and venous oxygen saturation (SvO2 ) were obtained simultaneously at 3 Tesla field strength and 2.7-s temporal resolution during an 80-min time series using OxFlow, an in-house developed imaging sequence. The method yields whole-brain CMRO2 in absolute physiologic units via Fick's Principle. Nineteen subjects yielded evaluable data free of subject motion artifacts. Among these subjects, 10 achieved slow-wave (N3) sleep, 16 achieved N2 sleep, and 19 achieved N1 sleep while undergoing the MRI protocol during scanning. Mean CMRO2 was 98 ± 7(μmol min-1 )/100 g awake, declining progressively toward deepest sleep stage: 94 ± 10.8 (N1), 91 ± 11.4 (N2), and 76 ± 9.0 μmol min-1 /100 g (N3), with each level differing significantly from the wake state. The technology described is able to quantify cerebral oxygen metabolism in absolute physiologic units along with non-REM sleep stage, indicating brain oxygen consumption to be closely associated with depth of sleep, with deeper sleep stages exhibiting progressively lower CMRO2 levels.

The Effects of Wearing a 3-Ply or KN95 Face Mask on Cerebral Blood Flow and Oxygenation.

BackgroundThe SARS‐CoV‐2 virus has impacted life in many ways, one change being the use of face masks. Their effect on MRI‐based measurements of cerebral oxygen levels with quantitative susceptibility mapping (QSM) and cerebral blood flow (CBF) is not known.PurposeThis study investigated whether wearing a face mask leads to changes in CBF and cerebral venous oxygen saturation measured with MRI.Study TypeRepeated‐measures cohort study.PopulationA total of 16 healthy volunteers (eight male, eight female; 22–36 years) were recruited for the 3‐ply study. Ten of the 16 participants (five male, five female; 23–36 years) took part in the KN95 study.Field Strength/SequenceA 3 T, single‐delay 3D gradient‐and spin‐echo pseudo‐continuous arterial spin labeling (pCASL) scan for CBF quantification, and gradient‐echo for QSM and oxygenation quantification.AssessmentGray matter CBF and magnetic susceptibility were assessed by masking the pCASL CBF map and the QSM map to the T1‐weighted gray matter tissue segmentation. Venous oxygenation was determined from venous segmentation of QSM maximum intensity projections.Statistical TestsPaired Student's t‐tests and Cohen's d effect sizes were used to compare the face mask and no face mask scans for gray matter CBF, gray matter magnetic susceptibility, and cerebral venous oxygen saturation. Standard t‐tests were used to assess whether the order of scanning with and without a mask had any impact. A statistical cut off of P < 0.05 was used.ResultsThe 3‐ply masks increased gray matter CBF from an average of 43.99 mL/(100 g*min) to 46.81 mL/(100 g*min). There were no significant changes in gray matter magnetic susceptibility (P = 0.07), or cerebral venous oxygen saturation (P = 0.36) for the 3‐ply data set. The KN95 masks data set showed no statistically significant changes in gray matter CBF (P = 0.52) and magnetic susceptibility (P = 0.97), or cerebral venous oxygen saturation (P = 0.93).Data ConclusionThe changes in blood flow and oxygenation due to face masks are small. Only CBF increased significantly due to wearing a 3‐ply mask.Evidence Level2Technical EfficacyStage 3

Cerebral Venous Oxygen Saturation in Hypoperfusion Regions May Become a New Imaging Indicator to Predict the Clinical Outcome of Stroke.

To automatically and quantitatively evaluate the venous oxygen saturation (SvO2) in cerebral ischemic tissues and explore its value in predicting prognosis. A retrospective study was conducted on 48 AIS patients hospitalized in our hospital from 2015–2018. Based on quantitative susceptibility mapping and perfusion-weighted imaging, this paper measured the cerebral SvO2 in hypoperfusion tissues and its change after intraarterial rt-PA treatment. The cerebral SvO2 in different hypoperfusion regions between the favorable and unfavorable clinical outcome groups was analyzed using an independent t-test. Relationships between cerebral SvO2 and clinical scores were determined using the Pearson correlation coefficient. The receiver operating characteristic process was conducted to evaluate the accuracy of cerebral SvO2 in predicting unfavorable clinical outcomes. Cerebral SvO2 in hypoperfusion (Tmax > 4 and 6 s) was significantly different between the two groups at follow-up (p < 0.05). Cerebral SvO2 and its changes before and after treatment were negatively correlated with clinical scores. The positive predictive value, negative predictive value, accuracy, and area under the curve of the cerebral SvO2 were higher than those predicted by the ischemic core. Therefore, the cerebral SvO2 of hypoperfusion regions was a stronger imaging predictor of unfavorable clinical outcomes after stroke.

Quantitative Distribution of Cerebral Venous Oxygen Saturation and Its Prognostic Value in Patients with Acute Ischemic Stroke.

This study investigated the quantitative distribution of cerebral venous oxygen saturation (SvO2) based on quantitative sensitivity mapping (QSM) and determined its prognostic value in patients with acute ischemic stroke (AIS). A retrospective study was conducted on 39 hospitalized patients. Reconstructed QSM was used to calculate the cerebral SvO2 of each region of interest (ROI) in the ischemic hemisphere. The intraclass correlation coefficient (ICC) and Bland–Altman analysis were conducted to define the best resolution of the distribution map. The correlation between the cerebral SvO2 in hypoxic regions (SvO2ROI < 0.7) and clinical scores was obtained by Spearman and power analysis. The associations between cerebral SvO2 and unfavorable prognosis were analyzed using multivariate logistic regression. Excellent agreement was found between the cerebral SvO2 in hypoxic regions with a resolution of 7.18 × 7.18 × 1.6 mm3 and asymmetrically prominent cortical veins regions (ICC: 0.879 (admission), ICC: 0.906 (discharge)). The cerebral SvO2 was significantly negative with clinical scores (all |r| > 0.3). The cerebral SvO2 and its changes at discharge were significantly associated with an unfavorable prognosis (OR: 0.812 and 0.866). Therefore, the cerebral SvO2 in hypoxic regions measured by the quantitative distribution map can be used as an indicator for evaluating the early prognosis of AIS.

Invasive and non-invasive assessment of macro- and micro-circulatory effects of vasopressors during sevoflurane anesthesia in a pediatric experimental model: A randomized trial.

While non-invasive assessment of macro- and micro-circulation has the promise to optimize anesthesia management, evidence is lacking for the relationship between invasive and non-invasive measurements of cardiac output and microcirculatory indices. We aimed to compare the abilities of non-invasive techniques to detect changes in macro- and micro-circulation following deep anesthesia and subsequent restoration of the compromised hemodynamic by routinely used vasopressors in a randomized experimental study. A 20%-25% drop in mean arterial pressure was induced by sevoflurane in anesthetized mechanically ventilated just-weaned piglets (n=12) prior to the administration of vasopressors in random order (dopamine, ephedrine, noradrenaline, and phenylephrine). Simultaneous transpulmonary thermodilution cardiac output assessment with the invasive pulse index continuous contour (PiCCO) method was compared with non-invasive estimates obtained with electrical conductivity (ICON) and echo Doppler (Cardio Q). Changes in microcirculation were characterized by sublingual red blood cell velocity, jugular cerebral venous oxygen saturation, and arterial lactate. Cardiac output indices obtained by invasive and non-invasive methods. Changes in cardiac output measured invasively and non-invasively correlated significantly after sevoflurane (r=.78, p=.003 and r=.76, p=.006 between PiCCO and ICON or Cardio Q, respectively). Following the administration of vasopressors, invasive and non-invasive cardiac output assessments were unrelated with significant correlations observed only between PiCCO and ICON after dopamine and ephedrine. Sevoflurane-induced hypotension decreased jugular cerebral venous oxygen saturation significantly and was recovered by all vasopressors. Sevoflurane and vasopressors had no effect on red blood cell velocity, which increased only after dopamine. No consistent changes in lactate were observed during the study period. The results of this study suggest that non-invasive cardiac output measurements may not accurately reflect changes in macrocirculation after hemodynamic optimization by vasopressors. Due to the incoherence between macro- and micro-circulation, monitoring microcirculation is essential to guide patient management.

Sub-acute Changes on MRI Measures of Cerebral Blood Flow and Venous Oxygen Saturation in Concussed Australian Rules Footballers

BackgroundSports-related concussion (SRC) is common in collision sport athletes. There is growing evidence that repetitive SRC can have serious neurological consequences, particularly when the repetitive injuries occur when the brain has yet to fully recover from the initial injury. Hence, there is a need to identify biomarkers that are capable of determining SRC recovery so that they can guide clinical decisions pertaining to return-to-play. Cerebral venous oxygen saturation (SvO2) and cerebral blood flow (CBF) can be measured using magnetic resonance imaging (MRI) and may provide insights into changing energy demands and recovery following SRC.ResultsIn this study we therefore investigated SvO2 and CBF in a cohort of concussed amateur Australian Football athletes (i.e., Australia’s most participated collision sport). Male and female Australian footballers (n = 13) underwent MRI after being cleared to return to play following a mandatory 13-day recovery period and were compared to a group of control Australian footballers (n = 16) with no recent history of SRC (i.e., > 3 months since last SRC). Despite the concussed Australian footballers being cleared to return to play at the time of MRI, we found evidence of significantly increased susceptibility in the global white matter (p = 0.020) and a trend (F5,21 = 2.404, p = 0.071) for reduced relative CBF (relCBF) compared to the control group. Further, there was evidence of an interaction between sex and injury in straight sinus susceptibility values (F1,25 = 3.858, p = 0.061) which were decreased in female SRC athletes (p = 0.053). Of note, there were significant negative correlations between straight sinus susceptibility and relCBF suggesting impaired metabolic function after SRC.ConclusionsThese findings support the use of quantitative susceptibility mapping (QSM) and relCBF as sensitive indicators of SRC, and raise further concerns related to SRC guidelines that allow for return-to-play in less than two weeks.

MRI evaluation of cerebral metabolic rate of oxygen (CMRO2) in obstructive sleep apnea

Patients with obstructive sleep apnea (OSA) are at elevated risk of developing systemic vascular disease and cognitive dysfunction. Here, cerebral oxygen metabolism was assessed in patients with OSA by means of a magnetic resonance-based method involving simultaneous measurements of cerebral blood flow rate and venous oxygen saturation in the superior sagittal sinus for a period of 10 minutes at an effective temporal resolution of 1.3 seconds before, during, and after repeated 24-second breath-holds mimicking spontaneous apneas, yielding, along with pulse oximetry-derived arterial saturation, whole-brain CMRO2 via Fick’s Principle. Enrolled subjects were classified based on their apnea-hypopnea indices into OSA (N = 31) and non-sleep apnea reference subjects (NSA = 21), and further compared with young healthy subjects (YH, N = 10). OSA and NSA subjects were matched for age and body mass index. CMRO2 was lower in OSA than in the YH group during normal breathing (105.6 ± 14.1 versus 123.7 ± 22.8 μmol O2/min/100g, P = 0.01). Further, the fractional change in CMRO2 in response to a breath-hold challenge was larger in OSA than in the YH group (15.2 ± 9.2 versus 8.5 ± 3.4%, P = 0.04). However, there was no significant difference in CMRO2 between OSA and NSA subjects. The data suggest altered brain oxygen metabolism in OSA and possibly in NSA as well.

Impella RP Versus Pharmacologic Vasoactive Treatment in Profound Cardiogenic Shock due to Right Ventricular Failure.

The aim was to translationally compare a pharmacologic strategy versus treatment with the Impella RP in profound RV cardiogenic shock (CS). The pigs were allocated to either vasoactive therapy with norepinephrine (0.10 μg/kg/min) for the first 30 min, supplemented by an infusion of milrinone (0.4 μg/kg/min) for additional 150 min, or treatment with the Impella RP device for 180 min. Total RV workload (Pressure-volume-area × heart rate*103(mmHg/min)) remained unaffected upon treatment with the Impella RP and increased in the vasoactive group (CS 179[147;228] to norepinephrine 268[247;306](p = 0.002 compared to Impella RP) and norepinephrine + milrinone 366[329;422] (p = 0.002 compared to Impella RP). A trend towards higher venous cerebral oxygen saturation was observed with norepinephrine than Impella RP (Impella RP 51[47;61]% vs norepinephrine 62[57;71]%; p = 0.07), which became significantly higher with the addition of milrinone (Impella RP 45[32;63]% vs norepinephrine + milrinone 73[66;81]%; p = 0.002). The Impella RP unloaded the failing RV. In contrast, vasoactive treatment led to enhanced cerebral venous oxygen saturation.

Impella RP versus pharmacologic vasoactive treatment in profound cardiogenic shock due to right ventricular failure: Unloading and end-organ perfusion in a large animal model

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): The Danish Heart Foundation Unrestricted research grant from Abiomed Background No strong evidence exists regarding the treatment of cardiogenic shock (CS) caused by acute right ventricular (RV) failure which has mainly consisted of vasoactive drugs. There is expert agreement that treatment with the recently developed Impella RP is feasible, but no previous studies have compared vasoactive treatment strategies with the Impella RP in terms of cardiac unloading and end-organ perfusion. Hypothesis Treatment with the Impella RP device will be associated with lower RV myocardial workload (pressure-volume area) compared to vasoactive treatment strategies and can furthermore be achieved without compromising organ perfusion. Methods CS was induced by a stepwise injection of polyvinyl alcohol microspheres into the right coronary artery in twenty adult female Danish landrace pigs weighing 75-80 kg. After induction of CS, the pigs were allocated to one of the two interventions for 180 minutes: 1) vasoactive therapy comprised a continuous infusion of norepinephrine (0.1 µg/kg/min) for the first 30 minutes, supplemented by an infusion of milrinone (0.4 µg/kg/min) for the remaining 150 minutes or 2) immediate insertion of and treatment with the Impella RP. The results are presented as median [Q1;Q3]. Results Treatment with the Impella RP was associated with a lower RV workload compared to the vasoactive group, while no difference was observed with regards to left ventricular workload among intervention groups, Figure 1. Renal venous oxygen saturation increased to a similar degree following both interventions compared to the state of CS. A trend towards a higher cerebral venous oxygen saturation was observed with norepinephrine compared to Impella RP (Impella RP 51 [47;61] % vs Norepinephrine 62 [57;71] % ; p = 0.07), which became significantly higher with the addition of milrinone (Impella RP 45 [32;63] % vs Norepinephrine +Milrinone 73 [66;81] %; p = 0.002). Conclusion In this large animal model of profound CS caused by predominantly RV failure the Impella RP unloaded the failing RV. The vasoactive treatment, however, caused a higher cerebral venous oxygen saturation, while both interventions increased renal venous oxygen saturation to a similar degree. Abstract Figure 1

Quantitative Susceptibility Mapping of Venous Vessels in Neonates with Perinatal Asphyxia.

Cerebral venous oxygen saturation can be used as an indirect measure of brain health, yet it often requires either an invasive procedure or a noninvasive technique with poor sensitivity. We aimed to test whether cerebral venous oxygen saturation could be measured using quantitative susceptibility mapping, an MR imaging technique, in 3 distinct groups: healthy term neonates, injured term neonates, and preterm neonates. We acquired multiecho gradient-echo MR imaging data in 16 neonates with perinatal asphyxia and moderate or severe hypoxic-ischemic encephalopathy (8 term age: average, 40.0 [SD, 0.8] weeks' gestational age; 8 preterm, 33.5 [SD, 2.0] weeks' gestational age) and in 8 healthy term-age controls (39.3 [SD, 0.6] weeks, for a total of n = 24. Data were postprocessed as quantitative susceptibility mapping images, and magnetic susceptibility was measured in cerebral veins by thesholding out 99.95% of lower magnetic susceptibility values. The mean magnetic susceptibility value of the cerebral veins was found to be 0.36 (SD, 0.04) ppm in healthy term neonates, 0.36 (SD, 0.06) ppm in term injured neonates, and 0.29 (SD, 0.04) ppm in preterm injured neonates. Correspondingly, the derived cerebral venous oxygen saturation values were 73.6% (SD, 2.8%), 71.5% (SD, 7.4%), and 72.2% (SD, 5.9%). There was no statistically significant difference in cerebral venous oxygen saturation among the 3 groups (P = .751). Quantitative susceptibility mapping-derived oxygen saturation values in preterm and term neonates agreed well with values in past literature. Cerebral venous oxygen saturation in preterm and term neonates with hypoxic-ischemic encephalopathy, however, was not found to be significantly different between neonates or healthy controls.

Abstract 17303: Longitudinal Cerebral Oxygen Metabolism in Congenital Heart Disease

Background: Brain growth differences are apparent between different types of cyanotic congenital heart disease, but the underlying mechanism remains unclear. Here, we explored and characterized longitudinal cerebral hemodynamic and oxygen metabolism profiles and their relationships to brain growth patterns in infants with single ventricle physiologies (SV) and transposition of the great arteries (TGA). We hypothesized that there are marked differences in cerebral oxygen metabolism in those with SV compared with TGA. Methods: Cerebral blood flow (CBF), oxygen delivery (CDO2) and consumption (CVO2) and brain growth were measured in 103 term newborns with SV and TGA using MRI at pre- and post-surgery and at follow-up. We measured whole brain size by segmenting a 3D steady state free precession acquisition. Cerebral blood flow was measured using phase contrast imaging of the neck vessels and cerebral venous blood oxygen saturation was derived from T2 oximetry of the superior sagittal sinus. TGAs were divided into those with and without ventricular septums. Results: CBF profiles were similar between the 3 lesion groups. Cerebral oxygen delivery trends increased but were not significantly different between cardiac groups. We observed that this may be mediated by different mechanisms: an increase in arterial saturation in TGAs, and an increase in hemoglobin concentration in SVs. Cerebral oxygen consumption in SV infants remained low (p = 0.54) while that of TGA increased over time (TGA IVS p &lt; 0.001; TGA VSD p &lt;0.001) (Fig. 1), mediated by an unchanging oxygen extraction fraction in SVs (p = 0.59). The SV cerebral oxygen consumption profile aligned with their declining brain weight z-score trajectory. Conclusions: In conclusion, there are characteristic differences in hemodynamic adaptations between SVs and TGAs. Changes in oxygen metabolism may be facilitating brain growth trajectories. This informs us of possible mechanisms involved during a time of critical brain development.

Effects of milrinone on cerebral perfusion and postoperative cognitive function in spine surgery: Secondary analysis of a CONSORT-compliant randomized controlled trial.

Objective:To compare the effects of milrinone, sodium nitroprusside (SNP), and nitroglycerin (NTG) on induced hypotension, cerebral perfusion, and postoperative cognitive function in elderly patients undergoing spine surgery.Methods:Sixty patients >60 years scheduled for lumbar fusion surgery were assigned to receive milrinone (group M), SNP (group S), or NTG (group N). The administration of the study drug was initiated immediately after perivertebral muscle retraction and was stopped after completion of interbody fusion. Target blood pressure was a decrease of 30% in systolic blood pressure from baseline or mean blood pressure of 60 to 65 mm Hg. The regional cerebral venous oxygen saturation (rSVO2), as a measure of cerebral perfusion, and the change in perioperative Mini-Mental State Examination (MMSE) score, as a measure of postoperative cognitive function, were assessed.Results:During the administration of the study drug, the overall and lowest intraoperative rSVO2 values were significantly higher (P = .01 and P = .01, respectively), and the duration of rSVO2 <60% was shorter in group M than in the other groups (P = .03). In group M, intraoperative rSVO2 was not different from the basal value, whereas in groups S and N, rSVO2 was significantly lower than the basal value during the administration of the study drug, but then returned to the basal value after terminating the study drug. Basal MMSE scores were comparable among the 3 groups. The MMSE score on postoperative day 5 was higher in group M than the other groups.Conclusions:Milrinone used to induce hypotension resulted in better intraoperative cerebral perfusion and postoperative cognitive function compared to SNP and nitroglycerin.

Impella CP or VA-ECMO in profound cardiogenic shock: left ventricular unloading and organ perfusion in a large animal model.

The aim of this study was to evaluate the Impella CP over veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and their impact on left ventricular unloading and end-organ perfusion. Cardiogenic shock (CS) was induced by injecting microspheres into the left coronary artery in fourteen adult female swine. Impella CP or VA-ECMO was initiated in the presence of CS and evaluated after 60 minutes. Left ventricular pressure-volume area (PVA, total mechanical work) was obtained from a conductance catheter. Results are presented as mean (95% confidence interval) and the rank-sum test was used to assess differences between devices. Compared to the CS state, PVA was unaffected by Impella CP and increased on VA-ECMO (from 2,548 [2,193; 2,904] mmHg x mL during CS to 5,775 [4,451; 7,099], between device p-value=0.02). Arterial lactate increased during CS and decreased on support with no difference between devices. Renal venous oxygen saturation decreased during CS and increased on support with no difference between devices. Cerebral venous oxygen saturation increased to 33% [25, 40] on Impella CP and to 69% [49, 89] on VA-ECMO, p=0.04. In this porcine model of profound CS, Impella CP unloaded the left ventricle compared to VA-ECMO. Both devices improved end-organ perfusion, with a tendency towards higher venous oxygen saturations on VA-ECMO.

Reduced regional cerebral venous oxygen saturation is a risk factor for the cognitive impairment in hemodialysis patients: a quantitative susceptibility mapping study.

The purpose of this study was to noninvasively evaluate the changes of regional cerebral venous oxygen saturation (rSvO2) in hemodialysis patients using quantitative susceptibility mapping (QSM) and investigate the relationship with clinical risk factors and neuropsychological testing. Fifty four (54) hemodialysis patients and 54 age, gender and education matched healthy controls (HCs) were recruited in this prospective study. QSM data were reconstructed from the original phase data of susceptibility weighted imaging to measure the susceptibility of cerebral regional major veins in all subjects and calculate their rSvO2. The differences in rSvO2 between hemodialysis patients and HCs were investigated using analysis of covariance adjusting for age and gender as covariates. Stepwise multiple regression and correlation analysis were performed between the cerebral rSvO2 and clinical factors including neuropsychological testing. The SvO2 of the bilateral cortical, thalamostriate, septal, cerebral internal and basal veins in hemodialysis patients was significantly lower than that in HCs (p < 0.001, Bonferroni corrected). The cerebral rSvO2 in all these veins was reduced by 1.67% to 2.30%. The hematocrit, iron, glucose, pre-and post-dialysis diastolic blood pressure (DBP) were independent predictive factors for the cerebral rSvO2 (all P < 0.05). The Mini-Mental State Examination and Montreal Cognitive Assessment (MoCA) scores were both lower in patients than those in HCs (both P < 0.05). The SvO2 of the left cerebral internal vein correlated with MoCA scores (r = 0.492; P = 0.02, FDR corrected). In conclusion, our study indicated that the cerebral rSvO2 was reduced in hemodialysis patients, which was the risk factor for neurocognitive impairment. The hematocrit, iron, glucose, pre-and post-dialysis DBP were independent risk factors for the cerebral rSvO2.

Comparison of the Effects of Total Intravenous Anesthesia and Intravenous Inhalational Anesthesia on Brain Metabolism during Surgery

To compare the effects on the brain metabolism of propofol-remifentanil total intravenous anesthesia and desflurane-remifentanil intravenous inhalational anesthesia in neurosurgery. Methods: Thirty-four neurosurgical patients with intracranial space-occupying surgery were randomly divided into two groups: Group A was conducted with the propofol-remifentanil total intravenous anesthesia and Group B with desflurane-remifentanil intravenous inhalational anesthesia. The patients were monitored for the brain metabolism prior to anesthesia, 1 hour after surgery, 2 hours after surgery, and half an hour after surgery. Results: The cerebral venous oxygen saturation, jugular bulb oxygen partial pressure, jugular vein oxygen content, and arterial oxygen content of the patients in group B were significantly higher than that of group A (P<0.001); arterial-jugular oxygen content difference and brain oxygen uptake rate of group B were lower than that in group A. Conclusions: (1) Both anesthesia methods can reduce the cerebral oxygen consumption and brain oxygen uptake, and thus reduce the cerebral oxygen metabolism.

Effects of head-up vs. supine CPR on cerebral oxygenation and cerebral metabolism – a prospective, randomized porcine study

BackgroundRecent studies have shown that during cardiopulmonary resuscitation (CPR) head-up position (HUP) as compared to standard supine position (SUP) decreases intracranial pressure (ICP) and increases cerebral perfusion pressure (CPP). The impact of this manoeuvre on brain oxygenation and metabolism is not clear. We therefore investigated HUP as compared to SUP during basic life support (BLS) CPR for their effect on brain oxygenation and metabolism. MethodsTwenty pigs were anaesthetized and instrumented. After 8 min of cardiac arrest (CA) pigs were randomized to either HUP or SUP and resuscitated mechanically for 20 min. Mean arterial pressure (MAP), ICP, CPP, cerebral regional oxygen saturation (rSO2) and brain tissue oxygen tension (PbtO2) were measured at baseline, after CA and every 5 min during CPR. Cerebral venous oxygen saturation (ScvO2) was measured at baseline, after CA and after 20 min of CPR. Cerebral microdialysis parameters, e.g. lactate/pyruvate ratio (L/P ratio) were taken at baseline and the end of the experiment. ResultsICP was significantly lower in HUP compared to SUP animals after 5 min (18.0 ± 4.5 vs. 24.1 ± 5.2 mmHg; p = 0.033) and 20 min (12.0 ± 3.4 vs. 17.8 ± 4.3 mmHg; p = 0.023) of CPR. Accordingly, CPP was significantly higher in the HUP group after 5 min (11.2 ± 9.5 vs. 1.0 ± 9.2 mmHg; p = 0.045) and 20 min (3.4 ± 6.4 vs. −3.8 ± 2.8 mmHg; p = 0.023) of CPR. However, no difference was found in rSO2, PbtO2, ScvO2 and L/P ratio between groups after 20 min of CPR. ConclusionIn this animal model of BLS CPR, HUP as compared to SUP did not improve cerebral oxygenation or metabolism.

Reduced deep regional cerebral venous oxygen saturation in hemodialysis patients using quantitative susceptibility mapping.

Cerebral venous oxygen saturation (SvO2) is an important indicator of brain function. There was debate about lower cerebral oxygen metabolism in hemodialysis patients and there were no reports about the changes of deep regional cerebral SvO2 in hemodialysis patients. In this study, we aim to explore the deep regional cerebral SvO2 from straight sinus using quantitative susceptibility mapping (QSM) and the correlation with clinical risk factors and neuropsychiatric testing. 52 hemodialysis patients and 54 age-and gender-matched healthy controls were enrolled. QSM reconstructed from original phase data of 3.0T susceptibility-weighted imaging was used to measure the susceptibility of straight sinus. The susceptibility was used to calculate the deep regional cerebral SvO2 and compare with healthy individuals. Correlation analysis was performed to investigate the correlation between deep regional cerebral SvO2, clinical risk factors and neuropsychiatric testing. The deep regional cerebral SvO2 of hemodialysis patients (72.5 ± 3.7%) was significantly lower than healthy controls (76.0 ± 2.1%) (P < 0.001). There was no significant difference in the measured volume of interests of straight sinus between hemodialysis patients (250.92 ± 46.65) and healthy controls (249.68 ± 49.68) (P = 0.859). There were no significant correlations between the measured susceptibility and volume of interests in hemodialysis patients (P = 0.204) and healthy controls (P = 0.562), respectively. Hematocrit (r = 0.480, P < 0.001, FDR corrected), hemoglobin (r = 0.440, P < 0.001, FDR corrected), red blood cell (r = 0.446, P = 0.003, FDR corrected), dialysis duration (r = 0.505, P = 0.002, FDR corrected) and parathyroid hormone (r = -0.451, P = 0.007, FDR corrected) were risk factors for decreased deep regional cerebral SvO2 in patients. The Mini-Mental State Examination (MMSE) scores of hemodialysis patients were significantly lower than healthy controls (P < 0.001). However, the deep regional cerebral SvO2 did not correlate with MMSE scores (P = 0.630). In summary, the decreased deep regional cerebral SvO2 occurred in hemodialysis patients and dialysis duration, parathyroid hormone, hematocrit, hemoglobin and red blood cell may be clinical risk factors.

Decreased susceptibility of major veins in mild traumatic brain injury is correlated with post-concussive symptoms: A quantitative susceptibility mapping study.

Cerebral venous oxygen saturation (SvO2) is an important biomarker of brain function. In this study, we aimed to explore the relative changes of regional cerebral SvO2 among axonal injury (AI) patients, non-AI patients and healthy controls (HCs) using quantitative susceptibility mapping (QSM). 48 patients and 32 HCs were enrolled. The patients were divided into two groups depending on the imaging based evidence of AI. QSM was used to measure the susceptibility of major cerebral veins. Nonparametric testing was performed for susceptibility differences among the non-AI patient group, AI patient group and healthy control group. Correlation was performed between the susceptibility of major cerebral veins, elapsed time post trauma (ETPT) and post-concussive symptom scores. The ROC analysis was performed for the diagnostic efficiency of susceptibility to discriminate mTBI patients from HCs.The susceptibility of the straight sinus in non-AI and AI patients was significantly lower than that in HCs (P < 0.001, P = 0.004, respectively, Bonferroni corrected), which may indicate an increased regional cerebral SvO2 in patients. The susceptibility of the straight sinus in non-AI patients positively correlated with ETPT (r = 0.573, P = 0.003, FDR corrected) while that in AI patients negatively correlated with the Rivermead Post Concussion Symptoms Questionnaire scores (r = − 0.582, P = 0.018, FDR corrected). The sensitivity, specificity and AUC values of susceptibility for the discrimination between mTBI patients and HCs were 88%, 69% and 0.84. In conclusion, the susceptibility of the straight sinus can be used as a biomarker to monitor the progress of mild TBI and to differentiate mTBI patients from healthy controls.

Preliminary study of cerebral venous oxygen saturation in healthy people using MR quantitative susceptibility mapping

Objevtive To measure the magnetic sensitive figure of cerebral vein and to evaluate the gender and bilateral difference in normal human cerebral venous oxygen saturation and the correlation with age by MR quantitative susceptibility mapping (QSM). Methods Sixty right-handed healthy volunteers were enrolled in our study and underwent MRI and susceptibility weighted imaging (SWI) scan to acquire the phase and magnitude image of healthy people from November 2012 to September 2014. The susceptibility mapping(SM) was constructed from phase diagram and amplitude image by the susceptibility mapping imaging and phase artifacts removal toolbox (SMART) software. The region of interest (ROI) of bilateral cerebral veins (cerebral cortical veins, thalamostriate veins, septal veins, internal cerebral veins and basal veins of rosenthal) in SM was outlined manually by signal processing in nuclear magnetic resonance (SPIN). The Wilcoxon test was used to compare the gender-and side-difference of susceptibility measured by cerebral venous oxygen saturation. The Spearman correlation was used to calculate the correlation between the susceptibility of cerebral veins and age. Results The median susceptibility (extent) of left and right side cerebral cortical veins was 159.16(154.88-164.13)ppb(×10-9), 164.61(156.23-168.04) ppb, respectively. The median susceptibility (extent) of left and right side thalamostriate veins was 160.51 (152.14- 170.06) ppb, 162.48(153.47- 173.66)ppb, respectively. Left were less than the right, and the difference was statistically significant (Z=- 3.14, - 2.02, P<0.05). And the difference of two side of other cerebral venous susceptibility had no statistical significance. The median susceptibility (extent) of right cerebral cortical veins, left thalamostriate veins and right septal veins of 22 male was 166.22(159.21-169.99) ppb, 168.65(159.19- 174.45)ppb and 153.42(148.10- 161.78)ppb, respectively. The coresponding positions of median susceptibility (extent) of 38 female was 161.10(155.06- 167.15)ppb, 157.70(151.53- 164.41)ppb and 147.52(142.94- 154.16)ppb, respectively. The susceptibility of right cerebral cortical vein, left thalamostriate vein, right septal vein of male was significantly different from the females (Z=-2.03, -2.20, -2.33, P<0.05). Futhermore, we also found that there had positive correlation between age and right thalamostriate vein(r=0.28,P<0.05). Conclusion The magnetic sensitive of the right thalamostriate vein tends to increase along with the age, and some of peoples had difference with bilateral and age. Key words: Cerebral veins; Magnetic resonance imaging; Age factors