Cerebral Tissue Oxygenation Index Research Articles

Reproducibility of cerebral oxygenation measurement in neonates and infants in the clinical setting using the NIRO 300 oximeter*

To study reproducibility of cerebral tissue oxygenation index (cTOI) values in neonates and infants in a clinical setting using the NIRO 300 oximeter (Hamamatsu Photonics, Hamamatsu City, Japan). Clinical, observational study. University hospital, pediatric intensive care unit. Twenty neonatal and pediatric intensive care patients (age 0-190 days; median 4.5 days). Reproducibility of cTOI was measured at the lateral forehead of the patients. Sensor exchange experiments were performed by removing the sensor and reapplying another sensor (sensor 1 vs. sensor 2) at the same position. Simultaneous measurements, comparing cTOI values from the right and left forehead, were performed using both sensors. Corresponding sensor exchange experiments were performed within 10 mins. All tests were done under stable, steady-state cardiorespiratory conditions. Data were compared using Bland-Altman bias analysis and paired, two-sided Student's t-test (p < .05). Sensor exchange experiments and simultaneous left-to-right forehead measurements revealed only small mean differences (<5%) and no significant differences between corresponding values (p = .953/.164). However, Bland-Altman bias analysis revealed poor agreement with large 95% limits of agreement in particular for sensor exchange experiments (-17.8% to 17.6%) and less for simultaneous left and right measurements (-14.4% to 10.4%). The present study shows that cTOI measurements using the NIRO 300 oximeter at the lateral forehead of neonates and infants are not well reproducible under clinical conditions. This raises the question whether generally valid normal values can be defined with the used approach and makes it difficult to determine a normal range of cerebral oxygenation.

Comparison between cerebral tissue oxygenation index measured by near-infrared spectroscopy and venous jugular bulb saturation in children

To compare the cerebral tissue oxygenation index (TOI) measured by near-infrared spectroscopy (NIRS) with venous oxygen saturation in the jugular bulb (SjO(2)) during elective cardiac catheterization in children. Prospective observational clinical study in a catheterization laboratory for pediatric cardiology. Sixty children with congenital heart defects admitted to the catheterization laboratory. TOI measured noninvasively by NIRS was compared to SjO(2) measured in the jugular bulb during cardiac catheterization. Patients were divided into two groups regarding body weight: below (n=29) and above 10 kg (n=31). Linear regression analysis and Pearson's correlation coefficient were calculated. Bland-Altman analysis, sensitivity, and specificity calculation for spatially resolved near-infrared spectroscopy with a cutoff level of 60% were performed. Simultaneously measured values for SjO(2) (67.3+/-9.8%, 40-84.1%) and TOI (65.7+/-7.2%, 39-80%) showed a significant correlation; the correlation in children weighing under 10 kg was stronger in children weighing over 10 kg. Bland-Altman analysis showed a mean bias of -1.8% with limits of agreement between 11.7% and -15.3% for all children. Sensitivity and specificity of the SRS method were 46% and 91%, respectively, for all children and 53% and 83% respectively in infants weighing under 10 kg. The results demonstrate that despite a significant correlation, sensitivity of spatially resolved spectroscopy is poor, and it is questionable whether TOI can be used reliably to detect low SjO(2).

Near‐infrared spectroscopic cerebral oxygenation reading in neonates and infants is associated with central venous oxygen saturation

The aim of the study was to elucidate easily determinable laboratory and vital parameters in clinical practice to explain variability of near-infrared spectroscopic cerebral oxygenation readings in critically ill newborns and infants using the NIRO 300 spectrometer. Near-infrared spectroscopy (NIRS) cerebral tissue oxygenation index (cTOI) was measured on the forehead of critically ill neonates and infants with existing arterial and/or central venous access. We recorded patient characteristics and simultaneously determined sedation state, hemodynamic, respiratory and laboratory data, such as arterial blood gas analysis, electrolytes, hemoglobin and arterial lactate concentration, blood glucose and central venous oxygen saturation. Data were compared using linear, multiple and forward stepwise regression analysis (P < 0.05). A total of 155 neonates and infants aged from 0 to 365 days (median 12 days) were studied. cerebral tissue oxygenation index (cTOI) values ranged from 32.1 to 91.0% (60.5 +/- 11.5%). Simple linear regression analysis revealed significant associations between cTOI and arterial oxygen saturation (r = 0.254, P = 0.001), transcutaneously measured arterial oxygen saturation (r = 0.320, P < or = 0.0001), central venous oxygen saturation (r = 0.489, P < 0.0001), arteriovenous oxygen extraction (r = 0.445, P < 0.0001) and presence of a cardiac shunt (r = 0.250, P = 0.024). Multiple regression analysis and forward stepwise regression revealed two independent, significant predictors for cTOI, namely SvO2 (P < 0.0001) and presence or absence of a cardiac shunt (P = 0.003). SvO2 alone explained 23.9% of the variability of cTOI. The addition of the variable 'cardiac shunt' improved the model to 33%. Based on our study results cerebral tissue oxygenation readings by the NIRO 300 near-infrared spectrometer is influenced by central venous oxygen saturation, which partially explains intersubject variability of NIRS cerebral oxygenation readings.

86 Comparison Between Cerebral Tissue Oxygenation Index Measured by Near- Infrared Spectroscopy and Venous Jugular Bulb Saturation in Children

Background: Near-infrared spectroscopy (NIRS) provides a continuous, non-invasive method to measure regional changes in tissue oxygenation. Spatially resolved spectroscopy as an algorithm allows the calculation of the cerebral tissue oxygenation index (TOI) which expresses the ratio between oxygenated haemoglobin and total haemoglobin in the observed tissue. Objective: Comparison of the TOI measured by NIRS and venous oxygen saturation in the jugular bulb (SjO2) during cardiac catheterization. Additionally we investigated the influence of body weight on the validity of NIRS measuring.Methods: Patients: Fifty-three children (median age: 3.5 years, range: 0.1 to 16 years) admitted for cardiac catheterization of cyanotic and non-cyanotic congenital heart defects. Cerebral TOI was compared to SjO2 taken from the jugular bulb during cardiac catheterization. First, Pearson‘s correlation coefficients and p-values were calculated for all patients and than recalculated respectively for the Patients divided into two groups of over and under 10 kg body weight.Results: Simultaneously measured values for SjO2 (68.5 ± 9.8 %, 40–84.1 %) and cerebral TOI (66.4 ± 7.2 %, 39–80 %) showed a significant correlation (r= 0.6, p< 0.001). Correlation in the group of children under 10 kg (N= 22) was even stronger (r= 0.8, p< 0.001) whereas correlation in children over 10 kg body weight was only significant on the level p< 0.05 (r= 0.44).Conclusion: Cerebral tissue oxygenation measured by near- infrared spectroscopy shows a significant correlation with venous saturation of the jugular bulb. This correlation is stronger in children under 10 kg body weight which may be due to the higher transparency and convexity of the infantile skull.

20 Sevoflurane Effect on Cerebral Haemodynamics During Induction of Anesthesia in Young Children Assessed By Near Infrared Spectroscopy. Preliminary Results

Background: Induction of anaesthesia with anaesthetic gas might be a potential cause for cerebral impairment in the newborn and young infant. Near infrared spectroscopy - NIRS - is a continuous, non-invasive bedside technique that has been shown to a reliable to monitor cerebral oxygenation status in different conditions. Aim: To assess non-invasively by means of NIRS, cerebral oxygenation during the different steps of induction of anesthesia by sevoflurane. Study population: Children below 2 years of age undergoing elective surgery, without CNS and cardiac malformations were eligible for the study. Three infants aged from 20 to 24 months (20, 22 and 18-month older) have completed the experiment and their data were analysed, so far.Methods: Induction of anesthesia: under control condition an air oxygen mixture via circle system (face mask connected to a semiclodsed anaesthetic circuit) with an increasing dose (1% - 2% - 3%) of sevoflurane was administered to the child. NIRS was continuously recordedng with a 2-channel instrumentation. Each channel was placed in order to illuminate the tempo-parietal region on each side of the head. After a 60-s baseline (before the exposure to the gas), the stepwise increases of the gas concentration were marked on the NIRS recording. Haemodynamic responses to the different gas concentration have been assessed by NIRS. Oxygenated (O2 Hb), de-oxygenated (H Hb), total haemoglobin (tot Hb) and the derived CBV and TOI have been calculated. Heart rate (HR), blood pressure (BP), peripheral oxygen saturation (satO2) and carbon dioxide (CO2) have been monitored.Results: In all infants we have observed a clear increase in the cerebral blood volume during the administration of sevoflurane. There was an initial increase in the cerebral tissue oxygenation index. Particularly during step 1 and 2 we have seen a more pronounced increase, while during step 3 the increase was quite slow and not statistically significant. HR, BP and satO2 did not change significantly. CO2 slightly increased, but not significantly.Conclusion: In the present study, cerebral blood volume increases during the induction of anaesthesia with sevoflurane. Cerebral tissue oxygenation showed a significant increase especially during the first phase of the induction. As approximately 70% of the blood in the cerebral vascular bed is venous blood we can speculate that sevoflure related effect of decreasing venous return may have repercussion on the cerebral blood volume.

Investigation of cerebral haemodynamics by near-infrared spectroscopy in young healthy volunteers reveals posture-dependent spontaneous oscillations

Autonomic reflexes enable the cardiovascular system to respond to gravitational displacement of blood during changes in posture. Spontaneous oscillations present in the cerebral and systemic circulation of healthy subjects have demonstrated a regulatory role. This study assessed the dynamic responses of the cerebral and systemic circulation upon standing up and the posture dependence of spontaneous oscillations. In ten young healthy volunteers, blood pressure and cerebral haemodynamics were continuously monitored non-invasively using the Portapres® and near-infrared spectroscopy (NIRS), respectively. Oscillatory changes in the cerebral NIRS signals and the diastolic blood pressure (DBP) signal have been identified by the fast Fourier analysis. Blood pressure increased during standing and returned to basal level when volunteers sat on a chair. The mean value of cerebral tissue oxygen index (TOI) as measured by NIRS did not demonstrate any significant changes. Oscillatory changes in DBP, oxyhaemoglobin concentration [O2Hb] and TOI showed a significant increase when subjects were standing. Investigation of the low frequency component (∼0.1 Hz) of these fluctuations revealed posture dependence associated with activation of autonomic reflexes. Systemic and cerebral changes appeared to preserve adequate blood flow and cerebral perfusion during standing in healthy volunteers. Oscillatory changes in [O2Hb] and TOI, which may be related to the degree of cerebral sympathetic stimulation, are posture dependent in healthy subjects.

Relation of cerebral tissue oxygenation index to central venous oxygen saturation in children.

To evaluate the relationship between the cerebral tissue oxygenation index measured by near-infrared spectroscopy and central venous oxygen saturation (SvO2) after corrective surgery of congenital heart defects in children. Prospective observational clinical study. A tertiary neonatal and paediatric intensive care unit for paediatric cardiology. Neonates and children consecutively admitted to the paediatric cardiology intensive care unit after corrective surgery of non-cyanotic congenital heart defects. Forty-three children were studied. Cerebral tissue oxygenation index, measured non-invasively by near-infrared spectroscopy, was compared to SvO2, measured by a catheter placed in the right atrium, and to haemodynamic and respiratory parameters. Pearson's correlation coefficients and p values were calculated. Simultaneously measured values for SvO2 (62.2+/-9.8%, 39.8-80.4%) and cerebral tissue oxygenation index (56.7+/-8.8%, 35.8-71.2%) showed a significant correlation ( r=0.52, p<0.001). Cerebral tissue oxygenation index and SvO2 are not interchangeable parameters, but cerebral tissue oxygenation index reflects the haemodynamic influence on cerebral oxygenation after cardiovascular surgery. Further work is necessary to confirm the clinical role of continuous non-invasive measurement of cerebral tissue oxygenation index with regard to the variations of global systemic oxygen consumption after cardiac surgery in children.

Measurement of changes in cytochrome oxidase redox state during obstructive sleep apnea using near-infrared spectroscopy.

To use near-infrared spectroscopy to investigate the effect of obstructive sleep apnea on cytochrome oxidase, the terminal enzyme of the mitochondrial respiratory chain. Observational study. Teaching hospital sleep unit. Subjects with diagnosed moderate to severe obstructive sleep apnea were recruited from the sleep clinic. Subjects were invited to attend 2 daytime sleep-study sessions, which included near-infrared monitoring of cerebral oxygenation and cytochrome-oxidase oxidation state. In addition, in study session 1, full polysomnography was performed (8 subjects, 303 apneas), and in study session 2, arterial oxygen saturation, cerebral blood flow velocity, and blood pressure were monitored (7 subjects, 287 apneas). In study session 1, mean (+/- SD) cytochrome-oxidase changes ranged from 0.48 +/- 0.08 microM to 0.13 +/- 0.05 microM. The magnitude of cytochrome-oxidase change correlated significantly with the magnitude of change in the cerebral tissue oxygenation index (P < .001). In study session 2, there were significant correlations between arterial oxygen-saturation changes and cytochrome-oxidase redox changes and between Doppler cerebral blood flow velocity changes and cytochrome-oxidase redox changes (P < .001 and P = .001, respectively). Changes in directly measured cerebral tissue saturation and changes in arterial saturation and cerebral blood flow velocity (the 2 main factors affecting cerebral oxygenation) are associated with changes in cytochrome-oxidase oxidation state. The reduced cerebral oxygenation that occurs during obstructive sleep apnea is associated with changes in the intracellular redox state.

Cerebral tissue oxygenation index in very premature infants

Aim: To describe normal values of the cerebral tissue oxygenation index (TOI) in premature infants. Methods: TOI was measured by spatially resolved spectroscopy in preterm infants on the first 3...

Acute effects of cigarette smoking on cerebral oxygenation and hemodynamics: A combined study with near-infrared spectroscopy and transcranial Doppler sonography

Cigarette smoking has been shown to increase cerebral blood flow velocity (CBFV) and reduce vasomotor reactivity temporarily. The aim of our study was to clarify whether this results from dilation of resistance vessels alone with subsequent increase in regional cerebral blood flow (rCBF), or an additional constriction of basal cerebral arteries. In 24 healthy smokers (mean age±S.D., 32.7±10.5 years), cerebral oxygenation and hemodynamics were monitored by transcranial Doppler sonography and near-infrared spectroscopy before, during, and after smoking a cigarette (nicotine 0.9 mg). We simultaneously recorded CBFV of both middle cerebral arteries, mean arterial blood pressure, skin blood flow, end-tidal CO 2, changes in concentration of cerebral oxyhemoglobin, deoxyhemoglobin, and total hemoglobin (μmol/l), and a cerebral tissue oxygenation index. Smoking increased CBFV ( p<0.01), oxyhemoglobin ( p<0.01), and total hemoglobin ( p<0.01). After smoking, the increase in CBFV and total hemoglobin persisted ( p<0.01), while oxyhemoglobin returned to baseline. Deoxyhemoglobin and cerebral tissue oxygenation index did not change during the whole procedure. During, but not after smoking, CBFV increase was correlated to ipsilateral changes in oxyhemoglobin and total hemoglobin ( p<0.05). The increase in oxyhemoglobin only during smoking and the lack of changes in deoxyhemoglobin and cerebral tissue oxygenation index indicate that smoking did not substantially increase rCBF. The smoking-induced elevation in CBFV might therefore be due to an additional constriction of the middle cerebral artery. The combined effects of smoking on basal cerebral arteries and arterioles might contribute to the increased stroke risk in smokers.

Some factors affecting cerebral tissue saturation during obstructive sleep apnoea.

Measurement of cerebral tissue saturation during obstructive sleep apnoea (OSA) may provide additional information to conventional peripheral oxygen saturation. Thirteen subjects with OSA (mean apnoea/hypopnoea index 65.7+/-27.9) were monitored using full polysomnography and monitoring of near-infrared cerebral tissue oxygenation index (TOI). One-thousand and thirty-six apnoeas and hypopnoeas were analysed, in terms of duration, sleep stage, arterial oxygen saturation (Sa,O2) dip, minimum Sa,O2, TOI dip and minimum TOI. Cerebral TOI is a measure of cerebral tissue saturation of haemoglobin with oxygen, calculated using near-infrared spatially resolved spectroscopy, which has been shown to have a high specificity for intracranial changes. Decreases in cerebral oxygenation were observed during apnoeas and hypopnoeas. Baseline TOI ranged from 50.1-73.0% and mean apnoea/hypopnoea related TOI dips ranged from 1.43-6.85%. Mean Sa,O2 dips varied from 3.8-21.7%. In regression analysis, factors significantly predicting the magnitude of the TOI dip were Sa,O2 dip, minimum Sa,O2, apnoea duration and rapid eye movement sleep stage. The effect of apnoea duration and sleep stage remained significant after Sa,O2 was included in the regression equation. Near-infrared spectroscopy provides a noninvasive technique for monitoring cerebral tissue saturation during obstructive sleep apnoea.