Cerebral Tissue Oxygen Saturation Research Articles

Effect of cranial osteopathic manipulative medicine on cerebral tissue oxygenation.

The use of cranial osteopathic manipulative medicine (OMM) to alter cerebral tissue oxygen saturation could play a role in the maintenance of cerebral homeostasis. To examine the effects of cranial OMM on cerebral tissue oxygen saturation (S(CT)O(2)) and cardiac autonomic function in healthy adults. Cranial OMM augmentation and suppression techniques and sham therapy were randomly applied to healthy adults. During cranial OMM and sham therapy, S(CT)O(2) of the prefrontal cortex was determined bilaterally by using near-infrared spectroscopy. Heart rate, blood pressure, and systemic arterial blood oxygen saturation (SaO(2)) were also measured. Power spectral analysis was applied to continuous 4-minute R-R intervals. Measurements were made during 2-minute baseline periods, during 4-minute applications of the techniques, and during 5-minute recovery periods. Twenty-one adults (age range, 23-32 y) participated in the present study. Differences in mean baseline measurements for the augmentation technique, suppression technique, and sham therapy were not statistically significant for heart rate, blood pressure, SaO(2), left S(CT)O(2), or right S(CT)O(2). During the suppression technique, there was a statistically significant decrease in both left (slope [standard deviation]= -0.33 [0.08] %/min, R(2)=0.85, P=.026) and right (slope [standard deviation]=-0.37 [0.06] %/min, R(2)=0.94, P=.007) S(CT)O(2) with increased cranial OMM time. However, neither the augmentation technique nor the sham therapy had a statistically significant effect on S(CT)O(2). Decreases in normalized low-frequency power of R-R interval variability and enhancements of its high-frequency power were statistically significant (P=.05) during cranial OMM and sham therapy, indicating a decrease in cardiac sympathetic influence and an enhanced parasympathetic modulation. The cranial OMM suppression technique effectively and progressively reduced S(CT)O(2) in both prefrontal lobes with the treatment time.

Influence of Ductus Arteriosus on Regional Tissue Oxygen Saturation after Birth

Background and Aim: In many neonates the ductus arteriosus (DA) remains open after transition after birth. Aim of the present study was to evaluate the influence of an open DA on cerebral and peripheral regional tissue oxygen saturation 15 minutes after birth.Methods: 44 healthy term neonates after elective caesarean section and normal adaption (APGAR 9/10/10) were measured in a prospective observational study. Regional tissue oxygen saturation of the brain (rSO2brain), forearm (preductal; rSO2pre) and calf (postductal; rSO2post) were measured 15 minutes after birth with near-infrared spectroscopy (NIRS). rSO2-values were calculated out of five reapplications of the sensor at each site. Arterial oxygen saturation and heart-rate were measured continuously by pulse oximetry on the right hand (preductal) and the left foot (postductal). Blood pressure measurement and evaluation of ductus arteriosus by echocardiography were performed immediately after the NIRS measurements.Results: 22 neonates with open DA were matched to 22 neonates with functionally closed DA. In neonates with open DA the rSO2brain (82.6%) was significantly higher compared to neonates with closed DA (76.4%). rSO2pre and rSO2post showed no significant difference between both groups. In neonates with open DA heart rate (144/min) was significantly lower compared to neonates with closed DA (152/min). Arterial oxygen saturation (pre-, and postductal) and blood pressure showed no significant difference between both groups.Conclusion: Term neonates with open DA have 15 minutes after birth higher cerebral tissue oxygen saturation and lower heart rate than neonates with functionally closed DA.

Lower Cerebral Oxygen Saturation in Preterm Compared with Term Infants During the First 24 Hours of Life

Background and aims: Frequency-domain near-infrared spectroscopy (FD-NIRS) enables longitudinal measurements of cerebral tissue oxygen saturation (StO2). The objective was to evaluate changes in cerebral oxygenation in preterm versus term infants during the first days of life.Methods: StO2 was repeatedly measured by FD-NIRS (Oxiplex TS, ISS Inc., Champaign, IL, USA) in preterm (n=11, gestational age 34+3/7 (32+1/7-35+5/7) weeks, birth weight 2.125 (1.150-2.922) kg) and term (n=8, gestational age of 39+6/7 (37+0/7-40+6/7) weeks, birth weight 3.535 (2.360-4.390) kg) infants within the following postnatal time intervals: 0-12h, 12h-24h, 24-36h, 36-48h and 48-72h. The optode was placed over the right temporo-parietal region. For each measurement, 3 separate recordings of at least 2 minutes each at 1Hz sampling rate were combined. Median (min.-max.) p-values by Wilcoxon rank-sum test are depicted.Results: At 6h and 18h, preterm infants had lower StO2 values 55.6 (54.2-57.6)% and 60.5 (47.3-66.0)% compared to term infants (64.9 (59.4-74.8)% and 68.7 (59.3-75.8)%; p=0.004 and p=0.024). In contrast, at 42h and 60h StO2 values were similar: 63.1 (57.0-69.0)% and 60.1 (54.1-67.4)% compared with 65.1 (58.9-72.4)% and 61.4 (56.6-70.5)%; p=0.262 and p=0.358.Conclusion: These results suggest that preterm infants have lower StO2 levels compared with term infants during the first day after birth. Inadequate cardio-respiratory adaptation may contribute to this finding.Funded by AKF-Grant E.03.27025.1, Faculty of Medicine Tuebingen.

The Relationship Between Electrocerebral Activity and Cerebral Fractional Tissue Oxygen Extraction in Preterm Infants

Impaired cerebral oxygen delivery may cause cerebral damage in preterm infants. At lower levels of cerebral perfusion and oxygen concentration, electrocerebral activity is disturbed. The balance between cerebral oxygen delivery and oxygen use can be measured by near-infrared spectroscopy (NIRS), and electrocerebral activity can be measured by amplitude-integrated EEG (aEEG). Our aim was to determine the relationship between regional cerebral tissue oxygen saturation (rcSO2), fractional tissue oxygen extraction (FTOE), and aEEG. We recorded longitudinal digital aEEG and rcSO2 prospectively in 46 preterm infants (mean GA 29.5 wk, SD 1.7) for 2 hr on the 1st to 5th, 8th, and 15th d after birth. We excluded infants with germinal matrix hemorrhage exceeding grade I and recordings of infants receiving inotropes. FTOE was calculated using transcutaneous arterial oxygen saturation (tcSaO2) and rcSO2 values: (tcSaO2 - rcSO2)/tcSaO2. aEEG was assessed by calculating the mean values of the 5th, 50th, and 95th centiles of the aEEG amplitudes. The aEEG amplitude centiles changed with increasing GA. FTOE and aEEG amplitude centiles increased significantly with postnatal age. More mature electrocerebral activity was accompanied by increased FTOE. FTOE also increased with increasing postnatal age and decreasing Hb levels.

Brain oxygenation monitoring during neonatal resuscitation of very low birth weight infants

To explore if regional cerebral tissue oxygen saturation monitoring by near-infrared spectroscopy (NIRS) is feasible during neonatal resuscitation of very low birth weight (VLBW) infants after birth. Cerebral tissue oxygen saturation was measured by NIRS in 51 VLBW infants (mean gestational age: 27.8 weeks) during the first 10 min after delivery. A regional cerebral tissue oxygen saturation signal was available after a median (interquartile range) age of 52 (44 to 68) s. In three infants the signal was obtained after 10 min of age. After delivery cerebral tissue oxygen saturation rose continuously from 37 (31 to 49) % at 1 minute of age and reached a steady state in the range of 61 to 84% ∼7 min after birth. Percentiles of cerebral tissue oxygen saturation of this cohort of preterm infants are given. Cerebral tissue oxygen saturation monitoring is feasible during neonatal resuscitation of VLBW infants within the first minutes of life.

Cerebral Oxygenation in Very Low Birth Weight Infants Supported With Sustained Lung Inflations After Birth

Sustained lung inflations (SIs) immediately after birth might decrease the need for subsequent mechanical ventilation in preterm infants. However, effects of SIs on oxygenation and hemodynamics are undetermined. Our aim was to study immediate effects of SIs on heart rate, arterial oxygen saturation, and cerebral tissue oxygen saturation in preterm infants supported with SIs after birth for lung recruitment. Heart rate, arterial oxygen saturation, and cerebral tissue oxygen saturation using near infrared spectroscopy was measured in 24 preterm infants of 28.0 (26.6-29.3) wk GA [median (interquartile range)] during resuscitation using up to three SIs of 20, 25, and 30 cm H2O of 15 s duration each followed by nasal continuous positive airway pressure (CPAP) as first line approach for respiratory support. During positioning and suctioning immediately after delivery infants became progressively hypoxemic and bradycardic before respiratory support was initiated. In 18 infants (75%), more than one SI were applied. During the last SIs, there was a rapid increase in the infants' heart rate and an increase in cerebral tissue oxygen saturation. Arterial saturation increased with slight delay. In conclusion, effective last sustained inflations increase heart rate and cerebral tissue oxygen saturation to be followed by an increase in arterial saturation.

Effect of phenylephrine and ephedrine bolus treatment on cerebral oxygenation in anaesthetized patients

How phenylephrine and ephedrine treatments affect global and regional haemodynamics is of major clinical relevance. Cerebral tissue oxygen saturation (Sct(O2) )-guided management may improve postoperative outcome. The physiological variables responsible for Sct(O2) changes induced by phenylephrine and ephedrine bolus treatment in anaesthetized patients need to be defined. A randomized two-treatment cross-over trial was conducted: one bolus dose of phenylephrine (100-200 µg) and one bolus dose of ephedrine (5-20 mg) were given to 29 ASA I-III patients anaesthetized with propofol and remifentanil. , mean arterial pressure (MAP), cardiac output (CO), and other physiological variables were recorded before and after treatments. The associations of changes were analysed using linear-mixed models. The CO decreased significantly after phenylephrine treatment [▵CO = -2.1 (1.4) litre min(-1), P<0.001], but was preserved after ephedrine treatment [▵CO = 0.5 (1.4) litre min(-1), P>0.05]. The was significantly decreased after phenylephrine treatment [▵ = -3.2 (3.0)%, P<0.01] but preserved after ephedrine treatment [▵ = 0.04 (1.9)%, P>0.05]. CO was identified to have the most significant association with (P<0.001). After taking CO into consideration, the other physiological variables, including MAP, were not significantly associated with (P>0.05). Associated with changes in CO, decreased after phenylephrine treatment, but remained unchanged after ephedrine treatment. The significant correlation between CO and implies a cause-effect relationship between global and regional haemodynamics.

Cerebral Tissue Oxygenation and Regional Oxygen Saturation Can Be Used to Study Cerebral Autoregulation in Prematurely Born Infants

The coupling of cerebral intravascular oxygenation (dHbD) with mean arterial blood pressure (MABP) was taken as a reflection of autoregulation assuming constant arterial oxygen content. However, this method is sensitive to movement artifacts. We examined whether the cerebral tissue oxygenation index (cTOI) and regional oxygen saturation (rScO2) may replace dHbD and changes in total Hb (dHbT), respectively. Correlation (COR) and coherence (COH) were used to measure the agreement of MABP with rScO2/dHbT and cTOI/dHbD. dHbD/cTOI and dHbT/rScO2 recordings of, respectively, 34 and 20 preterm infants in need for intensive care were studied during the first days of life. dHbD and cTOI were obtained with the NIRO300 and rScO2 and dHbT with the INVOS4100. Invasive MABP was measured continuously. COR and COH scores of MABP versus dHbD/dHbT were compared with the corresponding ones by replacing dHbD/dHbT by cTOI/rScO2, respectively. Generally, no significant score differences were found for dHbD/cTOI. Differences for dHbT/rScO2 were slightly larger but still within the normal variation of the parameters. Differences become insignificant when restricting calculations to epochs of larger variation in MABP (>10 mm Hg). Hence, we suggest that cTOI and rScO2 can be used to study cerebral autoregulation in newborns.

Prenatal tobacco exposure influences cerebral oxygenation in preterm infants

Aim Our aim was to determine the influence of prenatal tobacco exposure on regional cerebral tissue oxygen saturation (r cSO 2) and fractional tissue oxygen extraction (FTOE) in preterm infants. We hypothesized that as a result of vasoconstriction caused by prenatal tobacco exposure r cSO 2 would be lower and FTOE would be higher during the first days after birth in infants exposed to tobacco during pregnancy. Methods Sixty preterms were included in this prospective, observational cohort study (median gestational age 29.9 weeks, range 26.0–31.8, median birth weight 1248 g, range 615–2250). Fourteen infants had been exposed to tobacco during pregnancy. All mothers smoked more than five cigarettes a day till delivery. We measured r cSO 2 and transcutaneous arterial oxygen saturation (tcSaO 2) in all infants on days 1–5, 8, and 15. FTOE was calculated: FTOE = (tcSaO 2 − r cSO 2) / tcSaO 2. Results In preterm infants exposed to tobacco during pregnancy, r cSO 2 was lower during days 1, 2, and 8 after birth, median 73% versus 81%, 73% versus 80% and 71% versus 78% respectively. FTOE was higher during days 1 and 8 after birth, median 0.24 versus 0.15 and 0.26 versus 0.19 respectively. On the second day, FTOE tended to be higher, 0.18 versus 0.14. Conclusions During the first two days and day 8 after birth cerebral oxygen saturation is lower and oxygen extraction higher in preterm infants following prenatal tobacco exposure. Our data suggest that prenatal tobacco exposure may have an effect on cerebral oxygenation of the infant.

Cerebral Oxygenation During Anesthesia

Cerebral Oxygenation During Anesthesia: Correlation With Blood Pressure and Cardiac OutputWilliam W. Mantulin∗ and Lingzhong Meng∗∗University of California IrvineBeckman Laser Institute,∗ Laboratory for Fluorescence Dynamics∗ and Department of Anesthesiology∗∗Irvine, CADuring surgery, the anesthesiologist is tasked with monitoring, manipulating and maintaining the patient's key physiological parameters, especially of critical organs such as the brain. Generally, cerebral tissue oxygenation is not explicitly tracked, but a measure of Mean Arterial Pressure (MAP) is considered an adequate surrogate marker for sufficient cardiac output to satisfy cerebral oxygen demand. Avoidance of cerebral ischemia is an important consideration. Consequently, we have used a tissue oximeter (Oxipex TS; ISS, Inc.) to non-invasively and quantitatively monitor cerebral oxygenation (bilateral; frontal lobes) during surgery in more than two dozen patients (under IRB approved protocols). If blood pressure declines after inducing anesthesia, then the anesthesiologist pharmacologically intervenes with a pressor such as Ephedrine or Phenylephrine. Phenylephrine acts as a vasoconstrictor, whereas ephedrine stimulates cardiac output. We were intrigued by our preliminary observations that cerebral oxygenation (and oxygenated Hemoglobin concentrations) declined with administration of Phenylephrine, but remained unchanged with Ephedrine. Both pressors produced the anticipated increase in blood pressure. We sought a correlation of this observation through a direct monitor of cardiac output with a Doppler Esophageal device (Cardio Q, Deltex Inc.). The data clearly showed that administration of Phenylephrine induced a decrease in cardiac output and a correlation with (a decreasing) cerebral oxygenation. The cerebral blood volume and tissue oxygen saturation tracked with the blood pressure. Our observations are now engendering a reexamination amongst clinicians as to how best to understand the interplay between cardiac output, mean arterial pressure and the use of increased blood pressure as a means to better perfuse and oxygenate critical organs such as the brain.

Reproducibility of cerebral tissue oxygen saturation measurements by near-infrared spectroscopy in newborn infants

Early detection of cerebral hypoxemia is an important aim in neonatology. A relevant parameter to assess brain oxygenation may be the cerebral tissue oxygen saturation (StO(2)) measured by near-infrared spectroscopy (NIRS). So far the reproducibility of StO(2) measurements was too low for clinical application, probably due to inhomogeneities. The aim of this study was to test a novel sensor geometry which reduces the influence of inhomogeneities. Thirty clinically stable newborn infants, with a gestational age of median 33.9 (range 26.9 to 41.9) weeks, birth weight of 2220 (820 to 4230) g, postnatal age of 5 (1 to 71) days were studied. At least four StO(2) measurements of 1 min duration were carried out using NIRS on the lateral head. The sensor was repositioned between measurements. Reproducibility was calculated by a linear mixed effects model. The mean StO(2) was 79.99 ± 4.47% with a reproducibility of 2.76% and a between-infant variability of 4.20%. Thus, the error of measurement only accounts for 30.1% of the variability. The novel sensor geometry leads to considerably more precise measurements compared to previous studies with, e.g., ∼5% reproducibility for the NIRO 300. The novel StO(2) values hence have a higher clinical relevance.

Precision of cerebral oxygenation and hemoglobin concentration measurements in neonates measured by near-infrared spectroscopy

One source of error with near-infrared spectroscopy (NIRS) is the assumption that the measured tissue is optically homogeneous. This is not always the case. Our aim is to assess the impact of tissue homogeneity (TH) on the precision of NIRS measurements in neonates. On 36 term and 27 preterm neonates at least five 1-min measurements are performed on each subject using the OxiplexTS. The sensor position is slightly changed before each measurement while assessing TH. The precision for cerebral tissue oxygenation saturation (StO(2)) and total hemoglobin concentration (tHb) are calculated by repeated measures analysis of variance. The mean StO(2) is not significantly different between term and preterm infants. The mean tHb is significantly lower in preterm infants (p < 0.01). With increasing TH, the precision of StO(2) increase from 5.6 to 4.6% for preterm and from 11.0 to 2.0% for term infants; the precision of tHb increases from 10.1 to 7.5μM for preterm and from 16.4 to 3.5 μM for term infants. The precision for StO(2) is higher in term than in preterm infants. The precision for tHb shows no significant difference between the two groups. The precision of NIRS measurements correlates with tissue homogeneity.

“Prolonged” migraine aura: New information on underlying mechanisms

AbstractThe aim of this study is to identify the pathophysiology of “prolonged” migraine aura not clearly understood. We studied cortical cerebral microcirculation by Near Infrared Spectroscopy system (NIRS) and cerebral macrocirculation by transcranial Doppler (TCD) in 8 subjects (3 M and 5 F, age range 21–41 years) during spontaneous “prolonged” migraine aura in according to ICHD-II criteria 2004 (code 1.6.2.) up to 24 hours after the end of aura and compared the results with the headache-free periods. During aura NIRS showed a significant decrease of the Arterial Pulse Wave of Cerebral Microcirculation (APWCM) amplitude (−33 % ± 5.7), p&lt;0.001, and a significant increase of Cerebral Tissue Oxygen Saturation (SctO2) (+15.5 % ± 5.1), p&lt;0.001 contralateral to the symptoms of aura compared with the headache-free periods; TCD showed a significant increase of Pulsatility Index (+36.5 % ± 6.5), p&lt;0.001 and a significant decrease of the diastolic velocity in the posterior and middle cerebral artery contralateral to the symptoms of aura compared with the headache-free periods. In conclusion during “prolonged” migraine aura we find areas of cortical hypoperfusion corresponding to the topography of aura symptoms that are the result of a decreased metabolic demand rather than an ischemic mechanism.

Correlation between cerebral tissue and central venous oxygen saturation during off-pump coronary bypass graft surgery

We compared simultaneous regional cerebral oxygen saturation and central venous oxygen saturation at different time periods in 20 adult patients (median age, 57.9; range, 35 to 76 years) undergoing off-pump coronary artery bypass (OPCAB) graft surgery (n= 20). Mean arterial pressure (MAP), partial pressure of carbon dioxide (PcvCO(2)), heart rate, haematocrit (Hct), lactate and patient oxygen saturation (SpO(2)) were also recorded as a secondary analysis to determine independent predictors of cerebral desaturation and interactions between predictors. The cross-sectional analysis performed at each time point showed several significant moderate to strong positive correlations between central venous oxygen saturation and both right and left cerebral oxygen saturations; however, right cerebral saturations correlated better with central venous saturations than left cerebral saturation. Partial pressure of carbon dioxide (PcvCO(2)) was identified as a major predictor of cerebral saturation 0.59 (p < 0.001). Central venous saturation can be used as a surrogate measure of cerebral oxygen saturation during OPCAB surgery.

321 Reproducibility of Cerebral Tissue Oxygen Saturation Measurements by Near Infrared Spectroscopy in Newborn Infants

Objectives: Cerebral tissue oxygen saturation (StO2) may be a relevant parameter to assess brain oxygenation in intensive care. Near infrared spectroscopy (NIRS) is able to measure this parameter, but so far the reproducibility of such measurements has been too low due to inhomogeneities. The aim of this study was to test a novel sensor geometry, which is based on two source and two detector locations, which are arranged symmetrically to reduce the influence of superficial inhomogeneities.Methods: Thirty clinically stable, spontaneously breathing newborn infants with a gestational age of 34.2±3.1 weeks, birth weight of 2295±970g and postnatal age of 10.2±14.9 days were measured four times for one minute by NIRS on the lateral head. Between measurements the sensor was replaced. The reproducibility was calculated by a linear mixed effects model.Results: The mean StO2 was 79.99±4.47% with a reproducibility of 2.76% and a variability of 4.20% between infants. The error of measurement only accounts for 30% of the variability.Conclusions: The novel sensor geometry leads to much more precise measurements compared to previous studies (e.g. ∽5% reproducibility for the NIRO 300). For this reason the measured StO2 values do not require averaging and are therefore more clinically relevant.

221 Impact of Balloon Atrial Septostomy on Cerebral Oxygen Saturation and Oxygen Extraction in Neonates with Transposition of the Great Arteries

Background: Neonates with transposition of the great arteries (TGA) are at risk of hypoxic-ischemic brain-injury. Balloon atrial septostomy (BAS) improves mixing of oxygen-saturated and -desaturated blood. We determined the impact of BAS on regional cerebral tissue oxygen saturation (rcSO2) and fractional cerebral tissue oxygen extraction (FTOE) in neonates with TGA.Methods: Term neonates with TGA were included. RcSO2 was measured with near-infrared spectroscopy 2 hours (hrs) before, 2hrs after, and 24hrs after BAS for a two-hour period. Transcutaneous arterial oxygen saturation (tcSaO2) was measured simultaneously. FTOE was calculated: FTOE=(tcSaO2-rcSO2)/tcSaO2. In neonates who did not need BAS on clinical grounds, according to the attending cardiologist, tcSaO2 and rcSO2 were measured twice for a two-hour period: once within 24hrs after admission and once 24hrs later. Data were analysed by multi-level analysis and Mann-Whitney-U-test.Results: Nine neonates (median age: 1 day [range:0-18]) underwent BAS and four neonates (median age: 4 days [range:0-6]) did not. RcSO2 increased after BAS (from mean 37% to 49% to 64% [p=0.000]), as did tcSaO2 (from mean 68% to 81% to 84% [p=0.000]). FTOE decreased after BAS (from mean 0.46 to 0.40 to 0.25 [p=0.000]). Neonates who did not need BAS showed higher baseline rcSO2 and tcSaO2 compared to neonates who did (median 57% vs 35% [p=0.020] and 88% vs 77% [p=0.034], respectively). After BAS, there were no differences between both groups.Conclusion: In neonates with TGA in need of BAS, rcSO2 increased and FTOE decreased following BAS. This suggests improved cerebral oxygenation, which, possibly, protects against hypoxic-ischemic brain-injury.

Cerebral Oxygenation in Preterm Infants With Germinal Matrix–Intraventricular Hemorrhages

Preterm infants are at risk of developing germinal matrix hemorrhages-intraventricular hemorrhages (GMH-IVH). Disturbances in cerebral perfusion are associated with GMH-IVH. Regional cerebral tissue oxygen saturation (r(c)SO₂), measured with near-infrared spectroscopy, and fractional tissue oxygen extraction (FTOE) were calculated to obtain an indication of cerebral perfusion. Our objective was to determine whether r(c)SO₂ and FTOE were associated with GMH-IVH in preterm infants. This case-control study included 17 preterm infants with Grade I to III GMH-IVH or periventricular hemorrhagic infarction (median gestational age, 29.4 weeks; range, 25.4 to 31.9 weeks; birth weight, 1260 g; range, 850 to 1840 g). Seventeen preterm infants without GMH-IVH, matched for gestational age and birth weight, served as control subjects (gestational age, 29.9 weeks; range, 26.0 to 31.6 weeks; birth weight, 1310 g; range, 730 to 1975 g). R(c)SO₂ and transcutaneous arterial oxygen saturation were measured during 2 hours on Days 1 to 5, 8, and 15 after birth. FTOE was calculated as FTOE=(transcutaneous arterial oxygen saturation-r(c)SO₂)/transcutaneous arterial oxygen saturation. Multilevel analyses showed that r(c)SO₂ was lower and FTOE higher in infants with GMH-IVH on Days 1, 2, 3, 4, 5, 8, and 15. The largest difference occurred on Day 5 with r(c)SO₂ median 64% in infants with GMH-IVH versus 77% in control subjects and FTOE median 0.30 versus 0.17. R(c)SO₂ and FTOE were not affected by the grade of GMH-IVH. Preterm infants with GMH-IVH had lower r(c)SO₂ and higher FTOE during the first 2 weeks after birth irrespective of the grade of GMH-IVH. This suggests that cerebral perfusion is decreased persistently for 2 weeks in infants with GMH-IVH, even in the presence of mild hemorrhages.

Cerebral Oxygen Desaturation Events Assessed by Near-Infrared Spectroscopy During Shoulder Arthroscopy in the Beach Chair and Lateral Decubitus Positions

Patients undergoing shoulder surgery in the beach chair position (BCP) may be at risk for adverse neurologic events due to cerebral ischemia. In this investigation, we sought to determine the incidence of cerebral desaturation events (CDEs) during shoulder arthroscopy in the BCP or lateral decubitus position (LDP). Data were collected on 124 patients undergoing elective shoulder arthroscopy in the BCP (61 subjects) or LDP (63 subjects). Anesthetic management was standardized in all patients. Regional cerebral tissue oxygen saturation (Scto(2)) was quantified using near-infrared spectroscopy. Baseline heart rate, mean arterial blood pressure, arterial oxygen saturation, and Scto(2) were measured before patient positioning and then every 3 minutes for the duration of the surgical procedure. Scto(2) values below a critical threshold (> or = 20% decrease from baseline or absolute value < or = 55% for >15 seconds) were defined as a CDE and treated using a predetermined protocol. The number of CDEs and types of intervention used to treat low Scto(2) values were recorded. The association between intraoperative CDEs and impaired postoperative recovery was also assessed. Anesthetic management was similar in the BCP and LDP groups, with the exception of more interscalene blocks in the LDP group. Intraoperative hemodynamic variables did not differ between groups. Scto(2) values were lower in the BCP group throughout the intraoperative period (P < 0.0001). The incidence of CDEs was higher in the BCP group (80.3% vs 0% LDP group), as was the median number of CDEs per subject (4, range 0-38 vs 0, range 0-0 LDP group, all P < 0.0001). Among all study patients without interscalene blocks, a higher incidence of nausea (50.0% vs 6.7%, P = 0.0001) and vomiting (27.3% vs 3.3%, P = 0.011) was observed in subjects with intraoperative CDEs compared with subjects without CDEs. Shoulder surgery in the BCP is associated with significant reductions in cerebral oxygenation compared with values obtained in the LDP.

Cerebral tissue oxygen saturation and extraction in preterm infants before and after blood transfusion

ObjectivePreterm infants often need red blood cell (RBC) transfusions. The aim of this study was to determine whether haemoglobin levels before transfusion were associated with regional cerebral tissue oxygen saturation...

Pathophysiology of migraine attack with prolonged aura revealed by transcranial Doppler and near infrared spectroscopy

The aim of this study is to identify the pathophysiology of migraine attack with prolonged aura (between 1 h and 7 days) not clearly understood. We studied cortical cerebral microcirculation by an innovative near infrared spectroscopy system (NIRS) and cerebral macrocirculation by transcranial Doppler (TCD) in eight subjects (3 M and 5 F, age range 21-41 years) during spontaneous prolonged migraine aura and after 1, 2, 4, 6, 12 and 24 h since the end of aura and compared the results with the headache-free periods. During aura NIRS showed a significant decrease of the arterial pulse wave of cerebral microcirculation (APWCM) amplitude (-35%), p < 0.002, and an increase of cerebral tissue oxygen saturation (SctO(2)) (+15%), p < 0.008 ipsilateral to the headache pain and contralateral to the symptoms of aura compared with the headache-free periods; TCD showed a significant increase of pulsatility index (+38%), p < 0.001 and a significant decrease of the diastolic velocity in the posterior and middle cerebral artery ipsilateral to the headache pain and contralateral to the symptoms of aura compared with the headache-free periods. During prolonged migraine aura we found areas of cortical hypoperfusion corresponding to the topography of aura symptoms that were the result of a decreased metabolic demand rather than ischemic mechanism.