Quantitation of Pathlength in Optical Spectroscopy

Delpy, David T.; Arridge, Simon; Cope, M; Edwards, David G.; Reynolds, E. O. R.; Richardson, C. E.; Wray, Susan; Wyatt, John; Zee, Pieter van der

doi:10.1007/978-1-4684-5643-1_5

Cited by 52 publications

(18 citation statements)

References 5 publications

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“…The results are given in table 2. No differences were apparent between infants with and without intraventricular haemor rhages (which are very common in preterm infants), a finding that is in agreement with experimental studies in the rat, in which path length changed only slightly over a wide range of tissue absorption [4].…”

Section: Resultssupporting

confidence: 88%

Measurement of Optical Path Length for Cerebral Near-Infrared Spectroscopy in Newborn Infants

Wyatt¹,

Cope²,

Delpy³

et al. 1990

Dev Neurosci

Self Cite

168

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The time taken for an extremely short pulse of near-infrared laser light to traverse the heads of 6 preterm infants was measured after death. The values obtained were used to calculate a differential path length factor (DPF), defined as the mean distance travelled by the photons divided by the distance between the points where light entered and left the head. The DPF was found to be 4.39 ± 0.28. Knowledge of this factor will permit accurate quantitative measurements to be made by near-infrared spectroscopy of a range of indices of cerebral oxygenation and haemodynamics in live infants.

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Section: Resultssupporting

confidence: 88%

Measurement of Optical Path Length for Cerebral Near-Infrared Spectroscopy in Newborn Infants

Wyatt¹,

Cope²,

Delpy³

et al. 1990

Dev Neurosci

Self Cite

168

View full text Add to dashboard Cite

show abstract

“…The temporal distribution of light emerging from the tissue surface is then detected with a streak camera or photon counter. 34,35 The flight times relative to a reference pulse of individual photons are measured to obtain a histogram of the distribution of arrival times (temporal point spread function [TPSF]). By fitting the TPSF to a light transport model, values of absorption and scattering (μ a and μ s ′) can be calculated.…”

Section: The Evolution Of Cerebral Oximetrymentioning

confidence: 99%

Recent Advances in Application of Cerebral Oximetry in Adult Cardiovascular Surgery

Fischer

2008

Semin Cardiothorac Vasc Anesth

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Cerebral oximetry is a noninvasive technology that continuously monitors cerebral tissue oxygen saturation, which is a sensitive index of global cerebral hypoperfusion. On the basis of near-infrared spectroscopy technology, information is provided on the availability of oxygen in brain tissue at risk during numerous pathological conditions. Complementary to the arterial oxygen saturation measured by pulse oximetry, cerebral tissue oxygen saturation reflects regional cerebral metabolism and the balance of local cerebral oxygen supply/demand. Recently, patient management with the guidance of cerebral oximetry has resulted in improved patient outcomes. This review will briefly describe the physics behind cerebral oximetry and will provide an overview of the literature focusing primarily on articles published within the past 5 years.

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“…In the present study, in which we were dealing with lull-term neonates and infants, the angle between the optodes was 90°. It remains therefore arbitrary whether or not the optical pathlength of 4.4 is valid in this study [ 18], The NIRS instrument used (Radiometer, Copenhagen. Denmark), consisted of four semiconductor laser diodes with wavelengths of 904, 845,805 and 775 nm.…”

Section: Assessment O F Cerebral Hemodynamics and Oxygenation By N Ir Smentioning

confidence: 99%

Changes in Cerebral Hemodynamics and Oxygenation during Hypothermic Cardiopulmonary Bypass in Neonates and Infants

et al. 1996

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Delay in development after open-heart surgery in infants has frequently been reported. Inadequate brain perfusion and oxygenation during deep hypothermic cardiopulmonary bypass (CPB) may play an important role. We investigated the effect of CPB on cerebral perfusion and oxygenation in 12 neonates and infants (age 0–11 months) undergoing open-heart surgery. Changes in cerebral blood volume (ΔCBV; in ml/100 g brain tissue) and oxidation level of the intracerebral mitochondrial enzyme cytochrome aa₃ (ΔCytaa₃; in µmol/l) were measured with near infrared spectroscopy. Nasopharyngeal temperature (T_nas) for assessment of changes in brain temperature, and mean arterial blood pressure (MAP) were monitored continuously. CBV lowered during cooling and increased during rewarming. These changes were only related with changes in Tnas (p < 0.001; 0.07 ml·100 g^-1/°C). No relation was found with changes in MAP or pump flow rate of the heart-lung machine. During steady-state hypothermic CPB, changes in CBV were only related to changes in MAP (p < 0.001). The individual regression lines between ΔCBV and MAP became steeper at lower absolute T_nas. Cytaa₃ showed an increase shortly after the initiation of CPB in 9 patients, with a sustained decrease to baseline values in 8 patients towards the end of the CPB period. Two patients who had a circulatory arrest during CPB had a sharp decrease in Δcytaa₃ after cessation of the heart-lung pump and showed no complete recovery of ΔCytaa₃ to baseline at the end of the CPB period. We conclude that changes in CBV during CPB are related to changes in T_nas. During deep hypothermic steady-state CPB, changes in CBV and MAP were related to each other, suggesting lack of cerebral autoregulation. The large decrease in Cytaa₃ in 2 patients with circulatory arrest suggests that this procedure compromises energy metabolism of the brain cell.

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Quantitation of Pathlength in Optical Spectroscopy

Cited by 52 publications

References 5 publications

Measurement of Optical Path Length for Cerebral Near-Infrared Spectroscopy in Newborn Infants

Measurement of Optical Path Length for Cerebral Near-Infrared Spectroscopy in Newborn Infants

Recent Advances in Application of Cerebral Oximetry in Adult Cardiovascular Surgery

Changes in Cerebral Hemodynamics and Oxygenation during Hypothermic Cardiopulmonary Bypass in Neonates and Infants

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