Arterial and Venous Contributions to Near-infrared Cerebral Oximetry

2000 ◽  
Vol 93 (4) ◽  
pp. 947-953 ◽  
Author(s):  
H. Marc Watzman ◽  
C. Dean Kurth ◽  
Lisa M. Montenegro ◽  
Jonathan Rome ◽  
James M. Steven ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Oxygen Saturation ◽  
Frequency Domain ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Fixed Ratio ◽  
Cerebral Oximetry ◽  
Infrared Light ◽  
Arterial Oxygen

Background Cerebral oximetry is a noninvasive bedside technology using near-infrared light to monitor cerebral oxygen saturation (Sco2) in an uncertain mixture of arteries, capillaries, and veins. The present study used frequency domain near-infrared spectroscopy to determine the ratio of arterial and venous blood monitored by cerebral oximetry during normoxia, hypoxia, and hypocapnia. Methods Twenty anesthetized children aged < 8 yr with congenital heart disease of varying arterial oxygen saturation (Sao2) were studied during cardiac catheterization. Sco2, Sao2, and jugular bulb oxygen saturation (Sjo2) were measured by frequency domain near-infrared spectroscopy and blood oximetry at normocapnia room air, normocapnia 100% inspired O2, and hypocapnia room air. Results Among subject conditions, Sao2 ranged from 68% to 100%, Sjo2 from 27% to 96%, and Sco2 from 29% to 92%. Sco2 was significantly related to Sao2 (y = 0. 85 x -17, r = 0.47), Sjo2 (y = 0.77 x +13, r = 0.70), and the combination (Sco2 = 0.46 Sao2 + 0.56 Sjo2 - 17, R = 0.71). The arterial and venous contribution to cerebral oximetry was 16 +/- 21% and 84 +/- 21%, respectively (where Sco2 = alpha Sao2 + beta Sjo2 with alpha and beta being arterial and venous contributions). The contribution was similar among conditions but differed significantly among subjects (range, approximately 40:60 to approximately 0:100, arterial:venous). Conclusions Cerebral oximetry monitors an arterial/venous ratio of 16:84, similar in normoxia, hypoxia, and hypocapnia. Because of biologic variation in cerebral arterial/venous ratios, use of a fixed ratio is not a good method to validate the technology.

Quantification of adult cerebral hemodynamics by near-infrared spectroscopy

1994 ◽  
Vol 77 (6) ◽  
pp. 2753-2760 ◽  
Author(s):  
C. E. Elwell ◽  
M. Cope ◽  
A. D. Edwards ◽  
J. S. Wyatt ◽  
D. T. Delpy ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Infrared Spectroscopy ◽  
Oxygen Saturation ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Cerebral Hemodynamics ◽  
Arterial Oxygen ◽  
The Mean

Near-infrared spectroscopy was used to measure global cerebral blood flow and volume in 10 healthy adult volunteers. High- and low-cerebral blood flow compartments were detected with mean flows for all 10 subjects of 59 +/- 21 (SD) and 11 +/- 4 ml.100 g-1.min-1, respectively. The mean cerebral blood volume of the group was 2.85 +/- 0.97 ml/100 g. Analysis of spontaneous changes in the cerebral concentrations of oxyhemoglobin and deoxyhemoglobin demonstrated strong correlations between respiratory rate and the oscillation frequency of cerebral oxyhemoglobin concentration (r = 0.99) and arterial oxygen saturation (SaO2) (r = 0.99). An estimate of the mean cerebral oxygen saturation for all subjects averaged 59.4 +/- 12.4% when their mean SaO2 was 91.8 +/- 2.4% (equivalent to 67.6 +/- 13.8% at a normoxic SaO2 of 98%). These results demonstrate that near-infrared spectroscopy can be used as a noninvasive bedside technique for both qualitative and quantitative evaluation of cerebral hemodynamics and oxygenation in adults.

scholarly journals Cerebral perfusion and oxygenation are impaired by folate deficiency in rat: Absolute measurements with noninvasive near-infrared spectroscopy

2011 ◽  
Vol 31 (6) ◽  
pp. 1482-1492 ◽  
Author(s):  
Bertan Hallacoglu ◽  
Angelo Sassaroli ◽  
Sergio Fantini ◽  
Aron M Troen
Keyword(s):  
Cognitive Impairment ◽  
Infrared Spectroscopy ◽  
Oxygen Saturation ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Hemoglobin Concentration ◽  
Microvascular Dysfunction ◽  
Common Finding ◽  
Arterial Oxygen

Brain microvascular pathology is a common finding in Alzheimer's disease and other dementias. However, the extent to which microvascular abnormalities cause or contribute to cognitive impairment is unclear. Noninvasive near-infrared spectroscopy (NIRS) can address this question, but its use for clarifying the role of microvascular dysfunction in dementia has been limited due to theoretical and practical considerations. We developed a new noninvasive NIRS method to obtain quantitative, dynamic measurements of absolute brain hemoglobin concentration and oxygen saturation and used it to show significant cerebrovascular impairments in a rat model of diet-induced vascular cognitive impairment. We fed young rats folate-deficient (FD) and control diets and measured absolute brain hemoglobin and hemodynamic parameters at rest and during transient mild hypoxia and hypercapnia. With respect to control animals, FD rats featured significantly lower brain hemoglobin concentration (72±4 μmol/L versus 95±6 μmol/L) and oxygen saturation (54%±3% versus 65%±2%). By contrast, resting arterial oxygen saturation was the same for both groups (96%±4%), indicating that decrements in brain hemoglobin oxygenation were independent of blood oxygen carrying capacity. Vasomotor reactivity in response to hypercapnia was also impaired in FD rats. Our results implicate microvascular abnormality and diminished oxygen delivery as a mechanism of cognitive impairment.

scholarly journals Perfusion Changes at the Forehead Measured by Photoplethysmography during a Head-Down Tilt Protocol

Biosensors ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 71
Author(s):  
Tomas Ysehak Abay ◽  
Kamran Shafqat ◽  
Panayiotis A. Kyriacou
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Venous Blood ◽  
Arterial Oxygen ◽  
Large Variability ◽  
Large Vein ◽  
The Subject ◽  
Induced Changes

Photoplethysmography (PPG) signals from the forehead can be used in pulse oximetry as they are less affected by vasoconstriction compared to fingers. However, the increase in venous blood caused by the positioning of the patient can deteriorate the signals and cause erroneous estimations of the arterial oxygen saturation. To date, there is no method to measure this venous presence under the PPG sensor. This study investigates the feasibility of using PPG signals from the forehead in an effort to estimate relative changes in haemoglobin concentrations that could reveal these posture-induced changes. Two identical reflectance PPG sensors were placed on two different positions on the forehead (above the eyebrow and on top of a large vein) in 16 healthy volunteers during a head-down tilt protocol. Relative changes in oxygenated ( Δ HbO 2 ), reduced ( Δ HHb) and total ( Δ tHb) haemoglobin were estimated from the PPG signals and the trends were compared with reference Near Infrared Spectroscopy (NIRS) measurements. Also, the signals from the two PPG sensors were analysed in order to reveal any difference due to the positioning of the sensor. Δ HbO 2 , Δ HHb and Δ tHb estimated from the forehead PPGs trended well with the same parameters from the reference NIRS. However, placing the sensor over a large vasculature reduces trending against NIRS, introduces biases as well as increases the variability of the changes in Δ HHb. Forehead PPG signals can be used to measure perfusion changes to reveal venous pooling induced by the positioning of the subject. Placing the sensor above the eyebrow and away from large vasculature avoids biases and large variability in the measurements.

scholarly journals Determinants of Cerebral Fractional Oxygen Extraction Using Near Infrared Spectroscopy in Preterm Neonates

2000 ◽  
Vol 20 (2) ◽  
pp. 272-279 ◽  
Author(s):  
Stephen P. Wardle ◽  
C. William Yoxall ◽  
A. Michael Weindling
Keyword(s):  
Infrared Spectroscopy ◽  
Oxygen Saturation ◽  
Near Infrared Spectroscopy ◽  
Negative Correlation ◽  
Oxygen Delivery ◽  
Near Infrared ◽  
Oxygen Extraction ◽  
Arterial Oxygen ◽  
Cerebral Oxygen ◽  
Short Period

Cerebral fractional oxygen extraction (FOE) represents the balance between cerebral oxygen delivery and consumption. This study aimed to determine cerebral FOE in preterm infants during hypotension, during moderate anemia, and with changes in the PaCO2. Three groups of neonates were studied: stable control neonates (n = 43), anemic neonates (n = 46), and hypotensive neonates (n = 19). Cerebral FOE was calculated from the arterial oxygen saturation measured by pulse oximetry, and cerebral venous oxygen saturation was measured using near infrared spectroscopy with partial jugular venous occlusion. Mean ± SD cerebral FOE was similar in control (0.292 ± 0.06), anemic (0.310 ± 0.08; P = 0.26), and hypotensive (0.278 ± 0.06; P = 0.41) neonates. After anemic neonates were transfused, mean ± SD cerebral FOE decreased to 0.274 ± 0.05 ( P = 0.02). There was a weak negative correlation with the hemoglobin concentration (n = 89, r = −0.24, P = 0.04) but not with the hemoglobin F fraction (n = 56, r = 0.24, P = 0.09). In the hypotensive neonates, there was no relationship between cerebral FOE and blood pressure (n = 19, r = 0.34, P = 0.15). There was a significant negative correlation between cerebral FOE and PaCO2 within individuals (n = 14, r = −0.63, P = 0.01), but there was no relationship between individuals (n = 14, r = 0, P = 1). Cerebral FOE was not significantly altered in neonates with either mild anemia or hypotension. There were, however, changes in cerebral FOE when physiological changes occurred over a relatively short period; Cerebral FOE decreased after blood transfusion and increased with decreasing PaCO2. As no change in cerebral FOE was seen during hypotension, it was speculated that cerebral oxygen delivery may have been maintained by cerebral blood flow autoregulation.

scholarly journals Wearable Near-Infrared Spectroscopy as a Physiological Monitoring Tool for Seals under Anaesthesia

2021 ◽  
Vol 13 (18) ◽  
pp. 3553
Author(s):  
Eva-Maria Bønnelycke ◽  
Gordon Hastie ◽  
Kimberley Bennett ◽  
Jana Kainerstorfer ◽  
Ryan Milne ◽  
...  
Keyword(s):  
Heart Rate ◽  
Infrared Spectroscopy ◽  
Real Time ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Arterial Oxygen Saturation ◽  
Arterial Oxygen ◽  
Physiological Monitoring ◽  
Monitoring Tool ◽  
Concentration Changes

Chemical immobilisation of pinnipeds is a routine procedure in research and veterinary practice. Yet, there are inevitable risks associated with chemical immobilisation, and the physiological response to anaesthetic agents in pinnipeds remains poorly understood. The current study used wearable continuous-wave near-infrared spectroscopy (NIRS) data from 10 trials of prolonged anaesthesia (0.5 to 1.4 h) induced through ketamine and midazolam in five grey seals (Halichoerus grypus) involved in other procedures. The aim of this study was to (1) analyse the effect of each compound on heart rate, arterial oxygen saturation (SpO2), and relative concentration changes in oxygenated [ΔO2Hb] and deoxygenated haemoglobin [ΔHHb] in cerebral tissue and (2) to investigate the use of NIRS as a real-time physiological monitoring tool during chemical immobilisation. Average group responses of ketamine (n = 27) and midazolam (n = 11) administrations were modelled using generalised additive mixed models (GAMM) for each dependent variable. Following ketamine and midazolam administration, [ΔHHb] increased and [ΔO2Hb] remained relatively stable, which was indicative of apnoea. Periods of apnoea were confirmed from respiratory band data, which were simultaneously collected during drugging trials. Given that SpO2 remained at 97% during apnoea, we hypothesized that increasing cerebral [ΔHHb] was a result of venous congestion as opposed to decreased oxygen delivery. Changes in heart rate were limited and appeared to be driven by the individual pharmacological actions of each drug. Future research could include simultaneous measures of metabolic rate, such as the relative change in concentration of cytochrome-c-oxidase, to guide operators in determining when apnoea should be considered prolonged if changes in [ΔHHb] and [ΔO2Hb] occur beyond the limits recorded in this study. Our findings support the use of NIRS as real-time physiological monitoring tool during pinniped chemical immobilisation, which could assist veterinarians and researchers in performing safe anaesthetic procedures.

Report of the National Institute of Neurological Disorders and Stroke Workshop on Near Infrared Spectroscopy

PEDIATRICS ◽  
1993 ◽  
Vol 91 (2) ◽  
pp. 414-417
Author(s):  
Deborah G. Hirtz
Keyword(s):  
Blood Flow ◽  
Infrared Spectroscopy ◽  
Oxygen Saturation ◽  
Cytochrome Oxidase ◽  
Near Infrared Spectroscopy ◽  
Neurological Disorders ◽  
Near Infrared ◽  
Arterial Oxygen ◽  
Infrared Range ◽  
Near Infrared Range

A workshop about near infrared spectroscopy (NIRS), an emerging technology used to measure cerebral oxygenation and blood flow, was sponsored by the Developmental Neurology Branch, Division of Convulsive, Developmental, and Neuromuscular Disorders of the National Institute of Neurological Disorders and Stroke in Bethesda, MD, on March 31 and April 1, 1992. This was an international work-shop designed to bring together experts in the development of this technology with clinical researchers. Topics covered included the history and background of the development of NIRS technology, experimental models for the use of NIRS, clinical experience with NIRS in the neonate and the intrapartum fetus, and current key research issues with regard to technology and clinical use. THE TECHNOLOGY Near infrared spectroscopy is a new application of an existing technology which can provide information about changes in cerebral oxygen saturation, cerebral blood flow and volume, and oxygen utilization in the brain. The technology has been used for a long time to monitor hemoglobin, but only more recently for cytochrome oxidase. It involves the same basic principle used in the pulse oximeter, which uses light in the visible range to detect changes in finger arterial oxygen saturation. The method is based on the fact that light in the near infrared range (700 to 1000 nm) can pass through skin, bone, and other tissues relatively easily and that there are characteristic absorption bands of oxygenated and deoxygenated hemoglobin, and of the mitochondrial enzyme cytochrome oxidase (or cytochrome AA3) in the near infrared range. When the near infrared beam is passed through tissue, a decrease in signal intensity results from the absorbance of the chromophores in the medium.

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