194 research outputs found
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Cerebral Arterial Oxygen Saturation Measurements Using a Fiber-Optic Pulse Oximeter
Background
A pilot investigation was undertaken to assess the performance of a novel fiber-optic cerebral pulse oximetry system. A fiber-optic probe designed to pass through the lumen of a cranial bolt of the type used to make intracranial pressure measurements was used to obtain optical reflectance signals directly from brain tissue.
Methods
Short-duration measurements were made in six patients undergoing neurosurgery. These were followed by a longer duration measurement in a patient recovering from an intracerebral hematoma. Estimations of cerebral arterial oxygen saturation derived from a frequency domain-based algorithm are compared with simultaneous pulse oximetry (SpO2) and emoximeter (SaO2) blood samples.
Results
The short-duration measurements showed that reliable photoplethysmographic signals could be obtained from the brain tissue. In the long-duration study, the mean (±SD) difference between cerebral oxygen saturation (ScaO2) and finger SpO2 (in saturation units) was
-7.47(±3.4)%. The mean (±SD) difference between ScaO2 and blood SaO2 was -7.37(±2.8)%.
Conclusions
This pilot study demonstrated that arterial oxygen saturation may be estimated from brain tissue via a fiber-optic pulse oximeter used in conjunction with a cranial bolt. Further studies are needed to confirm the clinical utility of the technique
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Measurements of Cerebral Arterial Oxygen Saturation using a Fiber-optic Pulse Oximeter
This pilot investigation was undertaken to assess the performance of a novel fiber-optic cerebral pulse oximetry system. A fiber-optic probe designed to pass through the lumen of a cranial bolt of the type used to make intracranial pressure measurements was used to obtain optical reflectance signals directly from the brain tissue. Preliminary results from seven patients measured in the operating theatre and ITU are presented. Estimations of cerebral arterial oxygen saturation derived from a frequency domain-based algorithm are compared with pulse oximetry (SpO2) and hemoximeter (SaO2) blood samples. The mean (plusmnSD) difference between cerebral oxygen saturation (ScaO2) and finger SpO2 (in saturation units) was -7.47(plusmn3 .4)%. The mean (plusmnSD) difference between ScaO2 and blood SaO2 was -7.37(plusmn2.8)%
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Evaluation of a Fiber-optic Esophageal Pulse Oximeter
A dual-wavelength fiber-optic pulse oximetry system was developed for the purposes of estimating oxygen saturation from the esophagus. A probe containing miniature right-angled glass prisms was used to record photoplethysmographic (PPG) signals from the esophageal wall. Signals were recorded successfully in 19 of 20 patients, demonstrating that PPG signals could be reliably obtained from an internal vascularized tissue site such as the esophageal epithelium. The value of the mean oxygen saturation recorded from the esophagus was 94.0plusmn4.0%. These results demonstrate that SpO2 may be estimated in the esophagus using a fiber-optic probe and this may be the first report of such measurements
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Photoplethysmographic signals recorded from human abdominal organs using a fibreoptic probe
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Pilot study in neonatal and pediatric oesophageal pulse oximetry
The primary objective of this proof-of-concept pilot study was to investigate the feasibility of detecting photoplethysmographic(PPG) signals and estimating blood oxygen saturation (Spo2) values from the esophagus of children and neonates. This vital measurement can be impossible to obtain at times when it is most needed during septic shock, circulatory collapse, or cardiac arrest
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Photoplethysmographic measurements from central nervous system tissue
A new system for measuring the oxygen saturation of blood within tissue has been developed, for a number of potential patient monitoring applications. This proof of concept project aims to address the unmet need of real-time measurement of oxygen saturation in the central nervous system (CNS) for patients recovering from neurosurgery or trauma, by developing a fibre optic signal acquisition system for internal placement through small apertures. The development and testing of a two-wavelength optical fibre reflectance photoplethysmography (PPG) system is described together with measurements in rats and preliminary results from a clinical trial of the system in patients undergoing neurosurgery. It was found that good quality red and near-infrared PPG signals could be consistently obtained from the rat spinal cord (n=6) and human cerebral cortex (n=4) using the fibre optic probe. These findings justify further development and clinical evaluation of this fibre optic system
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An oesophageal pulse oximetry system utilising a fibre-optic probe
A dual-wavelength fibre-optic pulse oximetry system is described for the purposes of estimating oxygen saturation (SpO2) from the oesophagus. A probe containing miniature right-angled glass prisms was used to record photoplethysmographic (PPG) signals from the oesophageal wall. Signals were recorded successfully in 19 of 20 patients, demonstrating that PPG signals could be reliably obtained from an internal vascularised tissue site such as the oesophageal epithelium. The value of the mean oxygen saturation recorded from the oesophagus was 94.0 ± 4.0%. These results demonstrate that SpO2 may be estimated in the oesophagus using a fibre-optic probe
First discovery of trans-iron elements in a DAO-type white dwarf (BD)
We have identified 484 lines of the trans-iron elements (TIEs) Zn, Ga, Ge,
Se, Br, Kr, Sr, Zr, Mo, In, Te, I, Xe, and Ba, for the first time in the
ultraviolet spectrum of a DAO-type WD, namely BD, surrounded
by the ionized nebula Abell 35. Our TIE abundance determination shows extremely
high overabundances of up to five dex -- a similar effect is already known from
hot, H-deficient (DO-type) white dwarfs. In contrast to these where a
pulse-driven convection zone has enriched the photosphere with TIEs during a
final thermal pulse and radiative levitation has established the extreme TIE
overabundances, {here the extreme TIE overabundances are exclusively driven by
radiative levitation on the initial stellar metallicity. The very low mass
() of BD implies that a
third dredge-up with enrichment of s-process elements in the photosphere did
not occur in the AGB precursor.Comment: 34 pages, 19 Figure
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